Sunday, 20 October 2013

Improving 'ecoliteracy' with a place-based, human-centered approach

This past summer, Frontiers in Ecology and the Environment launched 'EcoLiteracy,' a new series meant to facilitate 'better informed decision making for environmental policy.' Each article is written by educators who have found new and interesting ways to teach their students about ecology, management, and conservation. The latest installment in the series, by Carmen Cid and Richard Pouyat, focuses on the ecology of human-dominated landscapes. The authors argue that true ecoliteracy can only be achieved by recognizing humans as an influential and integral part of many modern ecosystems, and by studying those ecosystems in their entirety.

Cid and Pouyat begin by highlighting a major shift that has taken place within the field of ecology in recent years: our growing awareness that humans are an integral and influential part of ecosystems far and wide. Where scientists might previously have investigated 'ecology in the city,' they are increasingly now examining 'ecology of the city.' This shift in perspective allows an improved understanding of 'the feedbacks between the human and biophysical components of ecosystems.'

While this is certainly a step forward, the authors argue that it still falls short of what we can achieve. They promote a more 'human-centered' approach whereby scientists cease to be merely observers, and instead become a more integral part of the ecosystem being examined. This shift to a 'place-based' perspective should inevitably make researchers more aware of the implications and potential applications of their observations, since it facilitates recognition of both the needs of a society and the likely impacts of policy decisions. While place-based work has previously been done in several long-term study sites, these rarely have been areas with large human footprints (in modern times, at least).

One advantage of place-based research is that it increases opportunities for collaborations within the community and the pursuit of citizen science projects. Individuals, organizations, and government bodies would have the opportunity to engage with all steps of the scientific process--something that not would only improve their ecoliteracy, but also potentially foster attachment to nature and investment in, and ownership of, new policies and management practices. These sorts of projects will inevitably be interdisciplinary, which is why, the authors write, 'we need to train some ecologists to work at the interface of science, policy, and management, and to teach graduate students not only research skills but also communication, management, and "people" skills.'

Communicators, managers, scientists, and policy writers can all contribute to designing and advocating these new cross-disciplinary approaches, but Cid and Pouyat believe that ecologists can take the lead by pursuing outreach activities that target a wide range of audiences. Partnerships with NGOs, religious institutions, media organizations, and educators can all be used to improve local knowledge, create dialogues, and solicit participation in collaborative projects. For this to be possible, however, the authors insist that it is crucial for ecologists to 'improve [their] delivery (translation and medication) of ecological knowledge' and 'be actively involved in managing the "supply and demand" of such knowledge.'

Cid, C.R. and Pouyat, R.V. 2013. Making ecology relevant to decision making: the human-centered, place-based approach. Frontiers in Ecology and the Environment 11(8):447-448.

Saturday, 19 October 2013

Of milk and men: use of dairy in early human societies

There are a number of animals that feature prominently in the daily lives of most Westerners, either directly or indirectly. Pet species like cats and dogs are, perhaps, the most obvious examples; others include the domestics from which we obtain meat and dairy--things like sheep, goats, and cows. Despite the importance of these animals, the majority of us are ignorant of how they came to be domesticated, or the ways in which our early ancestors interacted with these species and their products. Those are details that we can glean using three main techniques: archaeological digs in early human settlements; molecular analyses of bones, artifacts, and living animal descendants; and perusal of ancient documents and artwork.

The last of these was recently utilized by Irish geographer Finbar McCormick, who was interested in fleshing out our knowledge of how early human societies (in Mesopotamia, Egypt, India, and Europe) used dairy products. While this may sound like a rather esoteric research question, the results of the study have surprisingly broad implications: They help shed light on which groups of people developed particular types of dairying techniques and products, and which members of society were given access to dairy foods. This information, in turn, can be used to improve our knowledge of early religions, social hierarchies, health, and even the extent to which different countries interacted with each other.

Sheep, cows, and goats were domesticated many millennia ago (as long as 11,000, 10,5000, and 8,000 years ago, respectively). Documentary evidence for dairying, however, only dates to ~3,000 years ago--a fact that likely reflects a lack of historical evidence rather than a lack of actual dairying activity. According to McCormick, ancient sources can be difficult to interpret as a result of confusing or nonspecific wording. For example, there may be a single generic term for 'cheese' that fails to provide any information on whether it is soft or hard. This level of detail, however, is useful for understanding the amount of time and effort that would have been required for its creation, as well as guessing how and by whom might have been consumed.

Image courtesy of Hensons Cheese and Deli

Despite the drawbacks of working with scrolls and artwork, these sources can still shed light on early uses of dairy products. Mesopotamian literature for example, describes butter as being 'poured' from one container to another--indicating that it was likely clarified into a ghee-style product that could have been used like olive oil, and would have lasted much longer than modern-style butter in the hot Mesopotamian climate. The earliest Mesopotamian dairy image was found in a temple, which is unsurprising given that dairy items were only some of the many edible items offered to the gods. McCormick hypothesizes that the Mesopotamians might have pictured their goddess Ninhursag similarly to how the Egyptians envisioned Hathor--as a cow-like mother figure who could provide sustenance (in Hathor's case, directly to a young monarch, allowing him to become a 'true king').

Milk--and, indeed, cattle in general--seems to have been much more important in Vedic India than in the Fertile Crescent. As a result, cow imagery is liberally sprinkled through poems and hymns, and one Vedic text provides a list of the many different dairy products that could be obtained from a cow: milk (both fresh and boiled), cream, curds, sour cream, curdled milk, butter, ghee, clotted curds, and clotted whey. In addition to being consumed, milk products were also used liberally in religious ceremonies; among other things, ghee was a utilized as a fuel that could 'invigorate' the fires burning on altars.

Ghee (image courtesy of the Chopra Center)
It is unclear whether any of these earlier cheeses were prepared using rennet--a gut enzyme that facilitates the formation of curds and is essential to the production of hard cheeses. The first documentary evidence of rennet use dates to ~700 BC. In his Iliad, Homer describes 'grated' cheese--a form of dairy product that could only be generated through the use of rennet. Writing centuries later, Roman writers provided more detail on the dairying practices of the Greeks, describing both vegetable and animal rennets, and indicating which were most effective. Greek and Roman records indicate that cheese production was widespread, with markets supplying a wide variety of styles that had been made in distant locations; Pliny even wrote that Roman consumers could eat cheese imported from France.

Milk products appear to have had very little, if any, religious significance in mainland Europe. However, early documents suggest that dairy was recognized as being highly nutritious--though milk from sheep and goats was vastly preferred to that of cows. Despite this, the wording of several Roman texts suggests that excessive dairy consumption was considered uncivilized and barbaric. This seems to stem from negative feelings towards nomadic tribes that preferred keeping herds to engaging in agriculture. In Ireland, however, dairy could be a status symbol; while skimmed milk was a 'penitential' food, 'high-status' individuals could be found eating butter made from churned cream.

Cream (image courtesy of The Hungry Mouse, who also provides an excellent butter-making tutorial).
One particularly interesting aspect of Irish documentary evidence is the contribution made by fiction. For example, there is a traditional Irish story that mentions a cheese called tanach, which was loaded into a slingshot and flung at an enemy. The fact that tanach was able to withstand such treatment and act as a useful weapon suggests that it was a harder variety of cheese--something that is not made clear in other references. Mulach is another variety of hard cheese about which we know very little. There is, however, a myth about a giant with 'buttocks...the size of a mulach.' This description indicates that the wheels of this cheese must have been very large, indeed!

Though there is little evidence that dairy had widespread mystical use or meaning in early Britain and Ireland, there have been some intriguing discoveries that still require explanation. From at least the early Iron Age (4th century BC), small pots of butter were left in wetlands in both Ireland and Scotland. Although this practice become increasingly uncommon after the Middle Ages, some deposits were dated to as recently as the 18th century. This 'heathenish' folk practice was even incorporated into Christian worship in some areas, though it was clearly frowned upon by the Church. Thus, even in societies in which cows did not have a well-known or common religious significance, dairy products were still obviously regarded as being worthy and important.


These sorts of details would be difficult to uncover using archaeological and molecular techniques, which is why McCormick believes that documentary sources can make important contributions to his field. Despite this, he also acknowledges that these types of resources may be incomplete, biased (in terms of style and scope), and inaccurate (particularly in the case of artwork, which may be intended to convey metaphor rather than fact). As a result, McCormick writes, we do still have much to learn about the significance of cows and dairy products to early human cultures. It is his hope, however, that researchers can combine all three types of analytical technique to 'arrive at [a] greater understanding of the role of dairying in early societies.'

McCormick, F. 2012. Cows, milk and religion: the use of dairy produce in early societies. Anthropozoologica 47(2):101-113.

Sunday, 22 September 2013

Virtual gardens illuminate real-world attitudes about nature

Researchers have long struggled to design surveys that collect detailed and informative data without introducing bias through the use of loaded, confusing, or restrictive wording. A team of French researchers has come up with a novel solution to this problem: Toss out the surveys altogether, and replace them with a virtual computer program that allows respondents to express their thoughts and preferences in actions rather than in words.

This is the idea behind Virtual Garden, a program that allows users to select from 95 different features in order to create their ideal garden. The features fall within seven different categories: animals, flowers, lawn and cover, sport and playing, trees and bushes, water, and other. The program keeps track of each item that is added and adjusted, and calculates biodiversity as biotic features are introduced into the virtual habitat. Users are able to view the garden from multiple angles and even take a virtual stroll through the area in order to evaluate their progress and determine whether further manipulations need to be made to the environment.

Far from being merely a nerdy new version of The Sims, the program was designed to assess which features people most want to experience when they visit public gardens. Further, an analysis of the virtual habitats could help clarify the role that biodiversity has in driving humans' overwhelmingly positive responses to green spaces--particularly those located in otherwise urban areas. Finally, by collecting basic social, economic, and demographic information about each program user, the program's developers can also assess whether habitat preferences are influenced by age, education, income, and general interest in the natural environment.

The research team responsible for Virtual Garden trialled the program among 732 Parisian hospital patients. Each individual was given a 30-minute time limit for designing the garden, though the average length of time required was only 19.2 minutes. Gardens typically contained approximately 24 different features--9 "objects" (such as ponds), 5 animals, 8 flowers, and 5 woody species (trees or bushes). Overall, users included fewer biotic features than were expected by chance. Animals were particularly underrepresented, with nearly a third of gardens containing no animals at all, and almost another third containing fewer than 5 animal species. Larger animals--especially mammals and herptiles--were not very popular; the least preferred species overall were foxes and chimpanzees. Ladybugs, peacocks, and great tits, on the other hand, were the most preferred. The most popular species were generally those that are common in Parisian gardens, suggesting that patients tended to populate their virtual gardens with species that are most familiar to them.

Several demographic and socioeconomic factors influenced garden design. For example, men included fewer animals and flowers than women; younger patients included more non-native species; and people who showed a greater interest in conservation and nature activities tended to create gardens with higher biodiveristy. Interestingly, plant richness was higher in gardens created by people who grew up in more rural areas, again suggesting that familiarity with species is an important driver of habitat preferences.

The Virtual Garden trial produced two main results. First, it suggests that computer programs may be a useful way to collect data from people without accidentally introducing bias into a study. Such programs are likely to be particularly useful in situations where researchers need to address or describe situations that are highly visual in nature--such as habitat structure, the aesthetics of which can greatly influence respondents' attitudes and opinions. Second, the patterns reported here get us one step closer to understanding city-dwellers' complex and often contradictory responses to green spaces. There is particularly strong evidence of an "extinction-of-experience" process, whereby people judge biodiversity and aesthetics according to what they have previously experienced, rather than what may be natural, healthy, and/or desirable in a given environment.

The creators of the Virtual Garden hope that conservationists and managers can use their program to collect and compare data from across a wide geographic range, and, therefore, to improve our "understanding of the role culture and living context...play in people's relations with biodiversity." This could not only help save threatened species, but also improve the well-being of people by increasing and improving human-nature interactions even in the most urban of environments.

Shwartz, A., Cheval, H., Simon, L., and Julliard, R. 2013. Virtual Garden computer program for use in exploring the elements of biodiversity people want in cities. Conservation Biology 27(4):876-886.

Saturday, 21 September 2013

The Szechuan pepper: It's electric!

Szechuan peppers, which are responsible for spicing up a variety of Asian dishes, are considered unique among peppers for their "lemony overtones" and the tingling, almost electric, sensation that they cause in the mouths of consumers. The latter has been attributed to a compound known as hydroxyl alpha sanshool (also known simply as sanshool), but the neurological mechanism responsible for the effects of sanshool has not previously been understood. This inspired a research team from the University College London to perform a suite of experiments characterizing how eaters perceive Szechuan peppers, and exploring the sensory processes influencing these experiences. Their results suggest that the ubiquitously identified tingling sensation is produced by the activity of "rapidly adapting" (RA) sensory nerves that are more generally associated with mechanical, rather than chemical, stimuli.

(Szechuan pepper, also known as Sichuan or Szechwan pepper. There are at least two species responsible for this spice. Although the husk is generally considered the most important part of the plant for culinary purposes, some cooks may also work with leaves. The peppers may also be used in medicine. Image courtesy of Wikimedia.)

In the first portion of their study, the researchers applied a pepper solution to the lower lips of 12 volunteers; additional volunteers were also treated with ethanol and water control solutions. Each volunteer was asked to indicate whether his/her treatment produced a tingling, burning, cooling, warming, and/or numbing sensation. All individuals treated with the pepper solution agreed that it felt tingly. Although some people also described the ethanol treatment in this way, they indicated that the pepper solution resulted in a unique sensation that was both more intense and associated with a regular pulse.

The nature of this temporal effect was explored in more detail in the second part of the study. Volunteers were again treated with a swab of pepper solution applied to their lower lips. Once the tingling sensation began, the researchers applied a mechanical vibration to each volunteer's index finger, then asked the volunteers to indicate whether this vibration was of a higher or lower frequency than the feeling in their lips. Participant responses were used to adjust the frequency after each trial, thus allowing the researchers to gradually narrow in on the exact frequency of the pepper stimulus. Volunteers converged on a mechanical vibration frequency of 50.0 Hz, which happens to be near the midpoint of the range of frequencies (10-80 Hz) to which RA1 afferent fibers are most sensitive.

(Afferent nerves such as the RA1 are responsible for relaying information from sense organs, including skin, back to the brain. Image courtesy of Wikipedia.)

To double-check the legitimacy of comparing vibrations between lips and fingers, the researchers performed a third experiment in which eight volunteers were asked to compare the vibration frequencies of stimuli applied to first their lips and then their fingers, with a 1.5-s delay in between. Volunteers were most sensitive to convergence at a slightly lower frequency than that identified in the second experiment (46.4 Hz vs. 50.0 Hz). However, these two values are quite close, and the results clearly show that people are capable of relating sensations between fingers and mouths--suggesting that the researchers had come up with a suitable method for estimating pepper vibration frequencies.

In the final portion of the study, volunteers were exposed to both the mechanical and pepper stimuli sequentially. Because nerves need to "reset" between stimulus events, the second stimulus should have a lesser effect than the first--but only if both stimuli are activating the same set of nerves. After being exposed to an initial "adaptation stimulus" to their lips, volunteers were treated again with either a mechanical vibration or a pepper swab. A mechanical vibration was then applied to their fingers, and volunteers were asked to report on whether the frequency of this stimulus was higher or lower than that on their lips. As expected, volunteers had difficulty pinpointing the frequency of the second treatment, indicating that their nerves were still recovering from the adaptation stimulus. This was true regardless of whether the second treatment was a mechanical vibration or a pepper swab. In other words, both types of stimuli probably activate the same nerves.

(Hydroxy alpha sanshool, the compound responsible for the tingling sensation caused by Szechuan pepper. Gourmands might consider adding this chemical to their dishes in order to change the perception of other flavors, or to help diners experience food both chemically and mechanically. Image courtesy of Wikimedia.)

Taken together, results from the four experiments strongly suggest that the "light-touch" RA1 nerves are responsible for creating the tingling sensation that results from eating Szechuan pepper. Although sanshool is known to activate at least four other types of nerve fibers, a variety of factors--including the locations of those fibers and the types of sensation that sanshool produces when interacting with them--suggest that RA1 nerves are the most important player in producing a response to pepper-laden foods.

The authors suggest that these results may help us better understand the "pins and needles" sensations that are associated with some injuries and neural abnormalities. On a more fun note, however, they also point out that their findings may be of interest to gastronomists interested in enhancing their eating experiences. Szechuan pepper may not be the only food that influences taste by mimicking touch; we should be on the lookout for others that might similarly spice up our meals, both literally and figuratively. Further, because of the simultaneous chemical and mechanical effects of Szechuan peppers, chefs may be able to alter other flavors--or diners' perceptions of them--by adding sanshool to their culinary creations.

Hagura, N., Barber, H., and Haggard, P. 2013. Food vibrations: Asian spice sets lips trembling. Proceedings of the Royal Society B 280(1770): online advance publication.

Friday, 30 August 2013

Shortwave light pollution may contribute to moth declines

Research on the effects of nighttime pollution is still in its infancy. Scientists know that anthropogenic illumination has been steadily increasing over time--at a rate of ~6% per year--but have a limited understanding of which species it affects, and how. Nocturnal organisms seem particularly likely to suffer in the presence of light pollution, but a recent study indicates that responses to artificial illumination can vary even between close relatives--and that these variations can stem from differences in lighting regimes.

Artificial nighttime lighting. Image courtesy of EarthZine, which also features an interesting article about the impacts of nocturnal light pollution.

The study, conducted in a historical garden at the University of Exeter's Penryn Campus, found that shorter wavelength (whitish) lights attracted more moths than longer wavelength (yellowish) lights--especially when both types of light were broadcast simultaneously and moths had a choice between the two. This pattern was particularly strong for owlet moths (Noctuidae); geometer moths (Geometridae), on the other hand, were equally attracted to both short- and long-wave light. Both moth groups fall into the larger category of "macromoth," a set of species that have declined markedly in recent years.

Intriguingly, population decreases have been observed in nearly twice as many species of Noctuidae as Geometridae, suggesting that short-wave light pollution may have played an important part in the decline of these animals. For that to be confirmed, however, researchers will need to overlay maps of light pollution and moth decline and see whether the Noctuid decreases have been particularly noticeable in areas with shorter wavelength lighting.

A lesser broad-bordered yellow underwing, a.k.a. Noctua janthe. This is one of several noctuid species captured during the study. Image courtesy of Chris Harlow, via UK Moths.

The relatively simple methods used in the current study suggest that this follow-up work will not be too difficult to accomplish. During the summer (June-October) of 2012, the researchers broadcasted light from lamp-post structures fitted with either longer wavelength or shorter wavelength bulbs; lights were turned on both independently (e.g., short wavelength or long wavelength only) and together (e.g., both wavelength types broadcast simultaneously). Each light was fitted with safari traps designed to capture moths attracted to the glow. In the morning, researchers examined their captives and identified each to the species level. In addition to performing analyses on overall moth abundance and diversity, the scientists also investigated data concentrating only on the two most abundant families (Noctuidae and Geometridae) and species (Ochropleura plecta, a geometrid, and Noctua janthe, a noctuid).

While it may be easy to construct artificial light treatments, it may not be so simple to determine the mechanisms driving insect responses to the illumination. Both physiology and morphology (among other things) are likely to play important roles in light attraction: Moths are probably most attracted to the wavelengths to which their eyes are most sensitive, while their locomotion skills may help determine whether the animals are able to successfully wing their way towards the bulbs.

Flam shoulder, a.k.a. Ochropleura plecta, the geometrid most commonly caught during the current study. Image courtesy of Ian Kimber, via UK Moths.

Thus, researchers will probably need to take moths into the laboratory in order to collect data on these and other species-specific characteristics. It's unlikely that they will be able to study these traits in all 61 British macromoths that have recently experienced declines. However, careful selection of a few representative species may yield important findings that can illuminate a path towards improved management practices beneficial to these declining insects.

Somers-Yeates, R., Hodgson, D., McGregor, P.K., Spalding, A., and ffrench-Constant, R. 2013. Shedding light on moths: shorter wavelengths attract noctuids more than geometrids. Biology Letters 9(4): online advance publication.

Friday, 16 August 2013

Effects of Deepwater Horizon oil spill likely to last for decades

The catastrophic explosion on the Deepwater Horizon drilling platform allowed five million barrels of oil to gush into the Gulf of Mexico between April and July 2010. Since then, remediation and restoration efforts have helped to remove obvious signs of the disaster and return affected coastal communities to their pre-spill condition. But according to a recent study published in the academic journal PLoS ONE, the benthic, or sea-floor, environment around the disaster area still may require years to make a full recovery.

These conclusions were based on analyses of deep-sea sediment samples collected at 68 sites throughout the Gulf. The sampling locations, which were visited in autumn 2010, were selected because they radiate outward along a contamination gradient stretching away from the wellhead from which the crude oil flowed. The nearest sampling points were less than 1km from the wellhead, while the farthest were 125km away.

Emergency crews respond to the Deepwater Horizon explosion and spill. Image courtesy of the U.S. Coast Guard.

At each site, researchers characterised the physical properties of the benthic sediment and tested for signs of oil and other contaminants. They also quantified the abundance and diversity of benthic organisms commonly used as bioindicators: larger bottom-dwelling creatures known as macrofauna, and smaller species called meiofauna. A statistical technique called a principal component analysis (PCA) was then employed to look for relationships between these ecological variables.

The analysis revealed a clear link between contaminants associated with drilling (especially barium, polycyclic aromatic hydrocarbons, and total petroleum hydrocarbons) and the diversity of benthic creatures. Specifically, areas with more contaminants had very high abundances of nematodes relative to copepods, but low overall diversities of both nematodes and copepods. The driver of these results is unclear, but the researchers hypothesise that the influx of organic material from the oil spill might have led to a bacterial bloom. This would have been advantageous to bacteria-eating nematodes, but could have been harmful to copepods and nematodes with other diets.

To get a clearer picture of how these patterns were affected by each sampling site’s proximity to the wellhead, the researchers used a colour-coding scheme to label each site. Areas that had high contamination and low biodiversity (eg, those where the spill’s footprint was biggest) were marked in green, while areas with low contamination and high biodiversity (the smallest footprint) were labelled in red.
Map showing the footprint of the Deepwater Horizon oil spill at each of 68 sampling sites visited in late 2010. Gradient runs from green (least affected) through yellow to red (most affected). Image courtesy of Paul Montagna et al.
While the red sites tended to be in close proximity (within 3km) of the wellhead, orange and yellow site – those with moderate footprints – were more variable. This pattern was probably caused by an underwater plume of oil up to 200m thick and 2km wide in some areas that helped distribute contaminants along its path to the southwest of the wellhead. Because of this deep-sea flow of hydrocarbons, some distant habitats were more contaminated, while some closer ones were cleaner than expected.

The final step of the study was to increase the extent of the colour-coding and produce a map estimating the footprint across the entire region, rather than just at the 68 sampled points. This was achieved using an interpolation technique known as kriging, which allows researchers to extrapolate from the data they have collected to estimate values at other, non-sampled, sites. The result is a map that covers over 70,000km2 of benthic habitat, of which 167km2 is classified as moderately contaminated and another 24km2 of which is classified as severely contaminated.
Map estimating the regional footprint of the Deepwater Horizon oil spill. Green indicates areas least affected by the spill, while red indicates areas most affected. Image courtesy of Paul Montagna et al.
The biggest remaining question is how long the benthic community will continue to feel the negative effects of the spill. Gulf microorganisms will eventually be able to clean up their habitat, but this process could take a while given the cold temperature and low nutrient levels found in the contaminated area. In fact, given the lengthy recuperation period previously documented for past oil spills in shallower seas, the authors predict that it may take decades to undo the damage caused by the Deepwater Horizon blowout.

Montagna, P.A., Baguely, J.G., Cooksey, C., Hartwell, I., Hyde, L.J., Hyland, J.L., Kalke, R.D., Kracker, L.M., Reuscher, M., and Rhodes, A.C.E. 2013. Deep-see benthic footprint of the Deepwater Horizon blowout. PLoS ONE 8(8): e70540.

Sunday, 11 August 2013

Impacts of pharmaceuticals on wildlife

Pharmaceuticals have helped extend and improve the lives of humans and both wild and domestic animals, but researchers are increasingly worried about the effects that these chemicals could have on the wider environment. The compounds and their metabolites can be found in both terrestrial and aquatic ecosystems, in species great and small. Scientists have already documented several population declines linked to pharmaceutical activity, which raises an obvious question: What should we do to better understand--and potentially mitigate--the effects of drugs on wildlife and the ecosystems in which they live?

(Image courtesy of Loughborough University)

This question was the topic of a recent Research Fellow International Scientific Seminar funded by the UK's Royal Society. Scientists from a variety of fields met at the Royal Society's historic Chicheley Hall (Buckinghamshire) to think about what is already known, what needs to be explored in greater detail, and how all of this information might impact government policies in the future. The results of their discussion were then summarized in paper published in a recent edition of Biology Letters.

The researchers began by considering two pharmaceutical-wildlife interactions that have received quite a bit of press in recent years. The first is the feminization of male fish exposed to female hormones linked with hormone-replacement therapies and the birth control pill. Studies have shown that the fish are able to continue breeding, but at rates below those of normal males. This suggests that, over time, exposed populations might begin to die out. The second example described by the authors is the plight of Asian vulture species that have all but vanished as a result of widespread use of diclofenac, an anti-inflammatory and  pain-killer used in cattle. The near-absence of the scavenging birds in many areas has raised fears about potential water contamination, and has even impacted local burial practices (for a nice summary, see here).

(Vultures at a recent lion kill. Image courtesy of specialagentCK)

Cumulatively, the patterns associated with these events show that pharmaceuticals can act on non-target species, ultimately affecting individuals, entire populations, and even whole ecosystems. According to the researchers, the next step is to understand the details associated with these patterns--specifically, to uncover the "exposure pathways". This will require compiling information about the chemicals themselves (how often are they prescribed? what levels of bioactive compounds do they produce? how long do these compounds persist in the environment?), about the wildlife that may ingest them (which organisms help the compounds enter the food web? do some feeding methods promote uptake? what do the drugs do to the animals?), and about the effects of the drugs on both individual species and entire ecosystems (are some species impacted more than others? is there bioaccumulation? how much intra- and interspecies variation exists?).

The researchers point out that our widespread use of a variety of pharmaceuticals means that most organisms and environments will be exposed not just to a single drug, but to a cocktail of chemicals that may interact in unexpected ways. To further complicate the matter, other environmental stressors (e.g., extreme weather or a dearth of resources) may influence whether, and how, pharmaceuticals affect wildlife. Our current understanding of these patterns is particularly scanty for terrestrial environments. The authors note that work in developing countries may be especially enlightening because these are areas in which pharmaceutical use is increasing at a rate that outpaces the establishment of infrastructure that can remove chemicals from the ecosystem.

(Improved water treatment facilities and/or protocols might be one way of limiting the movement of pharmaceuticals into sensitive wildlife and ecosystems. Image courtesy of Wikimedia Commons.)

According to the researchers, "an integration of diverse approaches is required" to tackle this complex topic. Although the research may not be easy, it is likely to be extremely useful; there are already a number of species known to be negatively impacted by the spread of pharmaceuticals into wild areas, and the authors predict that further work may explain additional population declines that are, for the moment, mysterious. With this information in hand, we could begin to develop targeted conservation/management plans, improved water cleaning practices, tighter pharmaceutical regulations, and perhaps even more targeted medications that are less likely to affect other species.

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Arnold, K.E., Boxall, A.B.A., Brown, A.R., Cuthbert, R.J., Gaw, S., Hutchinson, T.H., Jobling, S., Madden, J.C., Metcalfe, C.D., Naidoo, V., Shore, R.F., Smits, J.E., Taggart, M.A., and Thompson, H.M. 2013. Assessing the exposure risk and impacts of pharmaceuticals in the environment on individuals and ecosystems. Biology Letters 9(4): online advance publication.

Wednesday, 7 August 2013

A scientific study of...restaurant menus?

Innovative ecologists have found useful data in a variety of interesting and sometimes unusual places--newspapers, photographs, art, and even the memories of people who were around when things were different than they are today. In the most recent issue of Frontiers in Ecology and the Environment, a group of marine biologists adds one more unexpected source to the list: restaurant menus.

 (Could menus like these provide valuable information on fish populations? Image courtesy of Cool Places--and Falmouth's The Shack.)

The researchers compare menus to the middens that are studied by archaeologists and historians. In colloquial terms, middens can be described as dumps or trash heaps, and are created by many species, including humans. Examination of middens allows researchers to investigate what ecological products have been utilized by an animal or society, as well as to study how consumption of that resource affected the local environment. Menus could be a modern counterpart to this, with analyses of their contents shedding light on which species were consumed during particular eras, how readily available they were, and how highly prized particular catches were relative to others. Indeed, previous researchers have already used menus to extract information about the popularity of certain seafood catches. In the current study, however, the authors were more interested in determining whether menus might reflect the local abundances of edible marine wildlife populations.

To explore this, the researchers collected 376 menus from 154 Hawaiian restaurants ranging from local dives to fancier sit-down establishments aimed at tourists. They focused on Hawaii because of its distance from the mainland; restaurants on the islands generally only serve locally sourced seafood, making the results of the study more easily interpretable. The menus cover nearly a fifty-year period (1928-1974) and were supplemented by government data on local fishery activity. These official records classified fish into five guilds (small pelagics, large pelagics, jacks, bottom fish, and reef fish); the researchers applied this same classification scheme to the fish found on each menu.

(A black jack, one of many jacks found off the coasts of Hawaii. Species like this declined in prevalence on restaurant menus from 1935 onwards, and became particularly uncommon after 1960. Image courtesy of Lurebook.)

Hawaii's nearshore fishery stocks decreased between 1940 and 1959, prompting the growth of pelagic fisheries; commercial landings of jacks, bottom fish, and reef fish all declined during this time. Likewise, the proportion of menus featuring these species markedly decreased from 1930 onwards, bottoming out around 1960. As the pelagic fishing industry took off in the late 1950s, restaurant menus featured an increasing number of both small and large pelagic fish species; by 1970, 95% of restaurant menus contained at least one large pelagic species.

For all five guilds examined here, curves for commercial landings are surprisingly similar to those for menu contents, though offset by a few years. This discrepancy may have been driven by public preference: Diners might have needed a few years to adjust to the idea of eating new types of fish (though the increasing scarcity of familiar species was likely a good incentive). Market availability might also have influenced the trends; animals that were landed may not always have been sold to restaurants, but instead may have been used for bait, sold to grocers, or consumed by the fishermen themselves. Regardless, menu content does seem to provide a rough estimate of the local abundance of edible fish species, suggesting that other researchers might be able to extract useful data from this unusual source of information.

(Certain menu items, including mollusks, frogs, and shrimps, did not reflect local populations of wild animals. This is because the seafood was either imported or raised in aquaculture. Image courtesy of The Pocahontas Files.)

That said, the authors do raise a number of potential issues with the use of restaurant menus in scientific research. For one thing, some species were more accurately represented than others. Mollusks and shrimps, for example, were generally imported from elsewhere, meaning that the menus did not provide much information on Hawaiian populations of these animals. Frogs, on the other hand, were produced by aquaculture rather than wild capture, and turtle meat was more likely to show up in local markets than in restaurants. In other words, researchers should familiarize themselves with the local seafood culture (fishing, eating, market dynamics, sourcing, public opinion) so that they can accurately interpret menu patterns.

For those intrepid scientists who decide to take on this challenge, the authors note that it could be interesting to conduct analyses not just of which species are featured, but also how much they cost--after all, particular dishes may continue to be served long after an animal has become rare, but this is likely to be accompanied by a noticeable hike in price.

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Van Houtan, K.S., McClenachan, L., and Kittinger, J.N. 2013. Seafood menus reflect long-term ocean changes. Frontiers in Ecology and the Environment 11:289-290.

Tuesday, 6 August 2013

UV-emitting diodes help keep endangered sea turtles out of gillnets

Although sea turtles and fish occupy the same marine habitat, their lifestyles are different enough that the two groups tend to vary in their sensory abilities. This is good news to conservationists looking to modify fishing gear so that it continues to catch fish, but no longer ensnares endangered turtles. One promising BRT, or bycatch reduction technology, is a diode that emits ultraviolet (UV) light. The rays can be detected by green, loggerhead, and leatherback sea turtles, but not by many of the most commercially valuable fish species. A recent study has shown that fishing gear fitted with these lights traps significantly fewer turtles, while continuing to capture normal amounts of target fish. Thus, the devices may help ease tensions between fishermen looking to make a living, and environmentalists hoping to protect threatened wildlife.

Green turtle, Chelonia mydas. Image courtesy of NOAA.
The diodes are the latest in a series of devices and modifications proposed for use by fishermen, and, in fact, are only the latest incarnation of net-illuminating gadgets. For example, one previous study found that green sea turtles tended to stay out of nets fitted with green light-emitting diodes (LEDs) and chemical lightsticks. The current study was conducted after researchers compared the visual ecology of sea turtles and fish and realized that the former were more sensitive to UV light than the latter. Though it seemed likely that use of UV lights could keep turtles away from nets without also warning off fish, the only way to test this theory was to deploy the devices in the field.

The researchers performed separate experiments (both in Mexico) in order to test their two hypotheses. The first experiment, conducted in a turtle-rich area known as Punta Abreojos, sought to determine whether the UV LEDs really did reduce sea turtle capture rates. Pairs of nets--one fitted with active LEDs and the other fitted with bulbs that weren't turned on--were deployed between sunset and sunrise. The researchers checked the nets every 90 minutes in order to retrieve, measure, and tag any turtles that had become ensnared. The second experiment, conducted in a commercial fishery in Bahia de los Angeles, was designed to investigate whether the LED devices affected fish capture. This part of the study used a paired-net design similar to that described above, only the nets were about four times as large and were left undisturbed all night. The next morning, all captured fish were retrieved and categorized as target species, bycatch, or "other" (e.g., kept by the fishermen as food or bait).

How a gillnet works. Image courtesy of the AFMA.

Of 332 green turtles captured during the first part of the study, only 123 (37%) were from UV-illuminated nets; the remaining 209 were captured from the nets without diodes. Although 123 is a sizeable number, the difference between lit and unlit nets was significant, indicating that use of these BRTs could substantially reduce turtle bycatch rates. Results from the second part of the study were similarly encouraging. Unlit nets only caught 46 more target fish than those fitted with UV lights (355 vs. 309); likewise, both types of net yielded catches with comparable average market values ($15.10 vs. $15.00).

These findings appear to be an excellent first step in the development and eventual distribution of a new turtle-deterring device. The UV LEDs may be improved by further behavioral studies exploring just how they work. In particular, it would be interesting to know whether turtles are avoiding the LEDs themselves, or whether the UV rays help the turtles see the fishing nets better. It will also be necessary to perform additional work that combines the two parts of this study into a single experiment; by choosing a field site that is both a commercial fishery and an area of high turtle density, scientists can investigate whether these BRTs are a practical solution to the problem of turtle bycatch.

Light-emitting diodes, or LEDs. Image courtesy of Instructables.
The authors of the study also point out that the current results may not be applicable to all fisheries, since different types of target fish have different visual abilities. Thus, the UV LEDs may work better in some sites than in others. Local conditions, such as time of day and turbidity of the water, may also affect the efficacy of the devices. While some tweaking may be necessary before the LEDs can be widely distributed, these preliminary findings suggest that the future of the apparati may be bright.

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Wang, J., Barkan, J., Fisler, S., Godinez-Reyes, C., and Swimmer, Y. 2013. Developing ultraviolet illumination of gillnets as a method to reduce sea turtle bycatch. Biology Letters 9(5), online advance publication.

Wednesday, 29 May 2013

Urban wildlife breeding success linked to forest patch size

Many species of native wildlife are abundant in anthropogenic areas, but this does not necessarily mean that their populations are healthy, or that the organisms will continue to thrive in human environments. Large numbers of raccoon dogs, for example, are known to inhabit forest patches within Tokyo, Japan, but a recent camera trap survey found that many adults are failing to breed. Together with the fact that hundreds of thousands of the animals become roadkill each year, the recent findings results suggest that Tokyo's raccoon dog population might diminish over time.

(Raccoon dog pups. Image courtesy of Zooillogix, which has a whole webpage describing raccoon dog biology.)

What is causing some raccoon dogs to forego breeding? Researchers aren't yet sure, but they suspect that the animals may be constrained by the size of their habitat patches. Conservationists have long argued about the best way to establish and link nature preserves; this is sometimes known as the "FLOSS" debate--Few Large Or Several Small? In urban areas--especially those where construction begins before an all-encompassing, landscape-level design plan can be developed--the only option may be to set aside several small preserves. While these can be adequate for smaller organisms such as insects or mosses, they may be insufficient for larger species such as raccoon dogs.

This was suggested by the results of the camera trap survey, which was conducted by a pair of researchers from the Tokyo University of Agriculture and Technology, and published in the journal PLoS ONE. The scientists distributed camera traps across 21 forest patches, ranging in size from 3.3 ha all the way up to 797.8 ha; all patches were bounded by major roads (>4 lanes). The traps were active between June and August, which is the period when recently born raccoon dog pups are in the company of their parents (before dispersing in September). The 443 resulting photographs were used to estimate detection rate and probability of occurrence for each site; these variables, in turn, were associated with habitat traits such as the size of the forest patch (or the amount of "local" forest), the amount of forest within 600 m of the focal patch (the amount of "landscape" forest), and the amount of forest cover (a variable that was later discarded because it had no effect on the focal measures).

(Camera trap photographs collected during the current study. Both photographs show adults, but a pup is present only in the left image. Image courtesy of PLoS ONE.)

Adult raccoon dogs were photographed in 100% of forest patches, but the researchers calculated that they probably only detected about 62% of all adults living in their study area. There was a slight effect of local patch size on adult detectability, but this was not very strong; in other words, full-grown raccoon dogs appear to use whatever habitat they can find, regardless of how expansive it is. However, only a subset of those individuals actually goes on to produce offspring--a key behavior, of course, in the perpetuation of the species. This pattern was reflected by the much lower number of pups photographed during the study: Pups were seen in only 62% of patches, and occupancy and detection rates were estimated to be ~66% and 28.5%, respectively. As was the case for adult raccoon dogs, pup numbers did not appear to be greatly affected by the landscape variable. However, the occurrence probability was much higher in larger patches. In other words, it appears that raccoon dogs are happy to shelter and feed in any available patch, but will only breed (or breed successfully) in larger areas of forest.

These findings seem to counter previously held assumptions that raccoon dogs are insensitive to urbanization. Adults typically have a large daily home range, and may choose not to breed when they face space constraints. Additionally, their preferred prey (ground beetles) are negatively impacted by both edge effects and reductions in patch size. Thus, the raccoon dogs appear to be affected both directly and indirectly by the size of their habitat. Particularly striking, though, was the lack of effect of the landscape variable: Raccoon dogs living in smaller patches weren't "rescued" by the presence of other nearby patches in which they could forage or raise young. This is likely a result of high mortality rates suffered on the bordering roadways; once the animals are isolated in small patches, they cannot easily go elsewhere.

(Tokyo: not an easy city in which to retrospectively introduce a forest. Image courtesy of the Japan National Tourism Organization.)

This suggests that urban planners should either aim to keep a few large reserves in the midst of their cities, or make sure that they provide corridors allowing safe passage between multiple smaller reserves--if they hope to preserve larger species of wildlife, that is. As the researchers point out, these sorts of decisions are best made before too much urbanization occurs, since the presence of infrastructure will drastically reduce flexibility. Forethought, they write, can be "crucial for preventing biodiversity loss worldwide and for managing forest ecosystems in urban landscapes."

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Soga, M. and Koike, S. 2013. Large forest patches promote breeding success of a terrestrial mammal in urban landscapes. PLoS ONE 8(1):e51802.

Monday, 27 May 2013

The power of historical ecology: a case study in Cape Cod's wetlands

Since the colonization of North American in the 17th century, few ecosystems have been so routinely and extensively disturbed as the salt marshes of Cape Cod. Among other things, residents have dug drainage ditches throughout the wetlands in order to make them less habitable to mosquitoes; developed the shoreline to facilitate the introduction of industrial, maritime, and residential facilities; and harvested huge numbers of edible wildlife off the coast. Over the past century or so, the human population has increased by approximately six-fold, placing extreme pressure on the wetland habitat. The most recent evidence of this burden is the spread of salt marsh die-offs, or "loss of foundation plant species to herbivores as a result of trophic dysfunction." Besides being unattractive, these die-offs threaten biodiversity and ecosystem function and may compromise the structural integrity of the wetland habitat.

Cape Cod wetlands. Image courtesy of Ms. Hanna's Room 202.
Researchers are scrambling to understand what caused these die-offs, how they may be exacerbated by current activities, and what we can do in the future to stem or reverse their spread. Cumulatively, these goals are at the heart of a relatively new scientific field called "historical ecology." Recognizing that ecological interactions can be quite complex and take many years to have noticeable effects on the environment, historical ecologists seek to use information from a variety of sources (including, for example, tree rings and soil cores) to reconstruct an ecosystem's experiences. Armed with these data, they can figure out the chain of events that resulted in contemporary problems--and, hopefully, suggest relevant management solutions.

These were the goals of a New England research team that recently utilized a series of aerial photographs to analyze the effects of anthropogenic disturbance on Cape Cod wetlands between 1939 (the date of their first photograph) and 2005. They obtained a total of 12 images (from 1939, 1976, 1994, and 2005) that they could use to track the state of the wetland over the years; their focal area was the amount of habitat covered by marsh vegetation in the original photograph.

An examination of the earliest photos revealed that the vast majority (>95%) of mosquito ditches had been created prior to 1939, laying the groundwork for significant changes to the Cape Cod habitat. Where these ditches were installed, high marsh plants were replaced by low marsh cordgrass, which is eaten by purple marsh crabs. Populations of these crabs are normally kept in check by predators such as blue crabs and striped bass, but these species are particularly desirable to fishermen--and fishermen were steadily increasing in the area: The period between 1939 and 1976 was marked by a near-tripling of the human population, not to mention a huge amount of coastal development (defined here as the installation of homes, docks, and marinas). In fact, >95% of human infrastructure was installed during this time; further construction was only halted by 1976 legislation forbidding any additional development.

Denuded marshland. Photograph courtesy of the Bertness Lab at Brown University.
Although the legislation was helpful for preventing further habitat loss, the damage had already been done. Though marshland die-offs had previously been thought to have begun in the 1980s, the researchers saw clear signs of denuding in the 1976 photographs; from then on, some areas lost >90% of their vegetation. All of this can be traced back to the purple marsh crabs, which, when released from predation pressure by the activity of fishermen, chomped their way through the encroaching low marsh cordgrass.

The most interesting thing about these findings is not when, or the extent to which, this denuding occurred, but where. All 12 of the researchers' study sites had experienced some amount of mosquito ditching, but development and die-off only affected some of those sites. Specifically, sites with high levels (>5%) of development had much greater die-off than sites with low levels (<5%) of development. Further, analyses showed that there was a synergistic relationship between mosquito ditching and development: Areas with the worst die-offs were those with both high levels of ditching and lots of development. These were the areas where anglers could fish most easily, and where the suddenly predator-less purple marsh crabs could find the largest amounts of low marsh cordgrass to eat.

Schematic showing how recreational fishing removed key predators of the purple marsh crab, thus allowing it (and other herbivorous relatives) to proliferate and eat its way through the low marsh cordgrass. Image courtesy of the Bertness Lab at Brown University.
The authors point out that, on its own, mosquito ditching was actually a "fairly benign" practice, and only became problematic when it was coupled with development. The introduction of the second type of disturbance created "diverging pathways" for the habitat, enabling crabs to enjoy the cordgrass buffet offered by highly-ditched, highly-developed areas that facilitated fishing activities. Without taking such a long-term, historical ecological view of the ecosystem, researchers might not have realized all the factors involved in the recent vegetation die-offs. The results highlight how some disturbances result in "unanticipated or novel outcomes" that can "remain wholly or partially unrealized and become apparent only following subsequent impacts or environmental changes." In this case, the latent disaster of the mosquito ditches only became a reality after nearly four decades of coastal development.

Based on these results, the scientists emphasize how important it is to see human impacts as "interactive effects of multiple disturbances," rather than looking at each disturbance in isolation. This is increasingly the mindset of researchers working in other habitats, as well--for example, urban ecologists who are now appreciating the combined effects of light, noise, and chemical pollution, along with physical habitat disturbances such as traffic and construction.

According to another publication by the current study's authors, invasive green crabs can help stem the Cape Cod die-offs--though these exotic animals may also have additional, unwanted, effects on the ecosystem. Image courtesy of Northrup Photography.
The researchers do not offer any new management solutions for the Cape Cod problem--that is an issue they have already written about elsewhere (see here and here for examples). Instead, the main point of their current paper is to show how their historical ecological techniques allowed them to pinpoint three major phases in marshland disturbance, as well as highlight the interconnectedness of those three types of disturbance. These patterns, the researchers say, allow them to "demonstrate that the ability of ecologists to understand and predict the consequences of future development on ecosystems is dependent on an understanding of the accumulation of latent human impacts already affecting them."

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Coverdale, T.C., Herrmann, N.C., Altieri, A.H., and Bertness, M.D. 2013. Latent impacts: the role of historical human activity in coastal habitat loss. Frontiers in Ecology and the Environment 11(2):69-74.

Saturday, 25 May 2013

Should traditional management practices be reintroduced into preserves?

For many of us, the term "nature preserve" tends to conjure up an image of a wild landscape that is either unmanaged or only lightly managed, and is undisturbed save for the quiet footfalls of the occasional hiker. While it's true that this picture does reflect conditions in a number of contemporary preserves, it wouldn't have been so accurate when these areas were first protected; further, this scenario may be just as "unnatural" as the highly disturbed, homogeneous landscapes that preserves are created to prevent.

Why? Because humans have been managing the land for thousands (in some places, tens of thousands) of years, and many of the species impacted by our activities have adapted to thrive under some level of environmental disturbance. In places where humans had little or no effect, other animals and processes have played a similar managerial role, keeping some species in check and allowing others to thrive. Many contemporary preserves lack these sorts of disturbance, and may be the poorer for it.

Cattle grazing, mowing, and haying are all traditional management techniques that may improve biodiversity in nature preserves. Further research is needed to understand potential drawbacks of these methods, and to compare them to alternatives.

This is an issue that has previously been addressed by botanists, historians, and anthropologists (for example, in M. Kat Anderson's Tending the Wild), but has not received much serious consideration from conservationists. A recent review in Biological Conservation, however, seeks to synthesize the existing literature and highlight the myriad ways in which traditional land management techniques might contribute to biodiversity and ecosystem stability in nature preserves.

Author Beth Middleton, of the United States Geological Survey, begins by pointing out that disturbances are a fact of life in all ecosystems. Things like wildfires, extreme storms, and grazing animals help shape habitats by killing off or reducing the growth of some organisms, thus allowing others to gain or keep a foothold. Early human management techniques (including periodic burning of meadows, grazing of small herds of cattle, wood cutting, and haying) may have had similar environmental effects by mimicking the effects of non-anthropogenic disturbances. More recently, however, we have generally attempted to protect parks and preserves from all such perturbations--thus potentially allowing dominant species to become so successful that they exclude other organisms. This is particularly problematic when the excluded organisms are protected species.

Some human disturbances mimic natural processes more than others. On the shores of this subterranean Californian soda lake, the more moderate management practices of indigenous Americans were replaced by more intense disturbances such as road and building construction.

Middleton is quick to stress that use of traditional management in preserves is a complex issue. For one thing, it may be difficult to convince people that their local nature preserve should be open to grazing by cattle, or that it is a good idea to allow loggers to periodically cut down a few trees. (In fact, Australian conservationists argued against these ideas in a recent essay posted on The Conversation.)

That said, a wide range of international studies suggest that traditional management could have major benefits. Low levels of cattle grazing, for example, have been found to promote biodiversity, and, in particular, to help rarer species thrive; this may be mediated by reductions in shrubby growth and dispersal of seeds in cattle dung. Some preserves have been created out of areas that were once heavily managed (for example, land that had previously been communally farmed by citizens of the former USSR). In these sites, maintenance of some level of disturbance can prevent macrophytes from encroaching and preventing the growth and persistence of smaller vegetative species. Middleton notes that the benefits of disturbance extend not just to plants, but also species that depend on vegetation for sustenance and shelter--including, for example, both insects and the organisms that feed upon them.

Fencing around Lake Nakuru, Kenya, excludes cattle and ensures that all resources can be utilized by native ungulates. Elsewhere in Kenya, the pattern is reversed, and in some places both types of animal can be found together.
Reintroduction of traditional management techniques is no simple matter, and Middleton describes the need for additional research. Particularly tricky is figuring out whether certain habitats were maintained by a single disturbance or an interaction between multiple different perturbations. In North America, for instance, prairies were impacted by both bison grazing and wildfires. While cattle might be adequate stand-ins for bison, the ecosystem might look quite different from its prehistoric form without the action of periodic fires. Further, cattle might have different grazing patterns than bison and could therefore have unanticipated side effects--such as inadvertently damaging insect populations by eating larvae attached to the vegetation. The impacts of reintroductions are likely to be influenced by a myriad of factors, including soil quality, plant growth patterns, humidity, and rainfall. Managers would probably need to rotate herds between different sites, and use fences to prevent overgrazing and physical damage. Another solution might be temporary introductions, where domestics like cattle and goats are brought in just long enough to nibble away any problematic woody vegetation--after which they are removed from the habitat.

A number of preserves have already successfully experimented with traditional grazing practices; non-livestock solutions such as haying and light mowing have also been advocated (for the protection of orchids in Europe, for example). For each of these techniques, it will be important to understand how much management is useful, and whether these practices are maximally beneficial at certain times or places. Biodiversity may peak just after mowing, for instance, but then decrease again as the grasses rebound to their original growth; meadows and fens may benefit more from traditional management than, say, wooded areas.

Some environmental disturbances are more extreme than others; both the geography and vegetation of the Mojave National Preserve have been significantly impacted volcanic activity.

The bottom line, says Middleton, is that we need to determine "what constitutes a natural disturbance, and how important [these are] in maintaining biodiversity in worldwide ecosystem types." We need additional studies examining the effects of small-scale cutting, grazing, and prescribed fire efforts, and we need to compare the outcomes of these practices with conditions from "prehistoric, indigenous, traditional agriculturalist, and contemporary times." Middleton argues that, rather than selecting regional-specific techniques for each preserve, we should create a global toolbox of techniques that can be used anywhere that management is needed. Once that has been achieved and we have a firm grasp on the science, we'll need to tackle the equally difficult task of convincing the public that these methods can protect biodiversity and preserve the integrity of natural areas.

Note: Some concepts/points that are not specifically attributed to B.A. Middleton may have been inspired by ideas from Kat Anderson's Tending the Wild.

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Middleton, B.A. 2013. Rediscovering traditional vegetation management in preserves: trading experiences between cultures and continents. Biological Conservation 158:271-279.

All photos by Flickr user specialagentCK.

Thursday, 23 May 2013

Does tourism revenue help birds in protected areas?

How much does tourism help fund bird conservation? Given the continuing boom of the "avitourism" industry, this sounds like the sort of question to which both environmentalists and entrepreneurs should know the answer. However, while researchers have performed calculations investigating the availability of tourism revenues for mammal and frog conservation efforts, nobody has explored similar trends in other taxa--or, to be more accurate, nobody had explored those trends until a group of Australian scientists recently decided to crunch the relevant numbers. The results of their analyses were reported earlier this month in the journal PLoS ONE.

(Grey-crowned crane living in the Kenya's Solio Game Preserve)

To make their study question a bit more manageable, the researchers focused on only a subset of all the 10,000-some extant bird species in the world and on only a portion of all the habitats in which these animals live. First of all, the researchers explored statistics relating only to the 562 species currently classified as Critically Endangered (CE; 190 species) or Endangered (EN; 372) on the IUCN Red List of Threatened Species. They also only counted tourism revenue generated by activity in one of the 120,000 or so protected areas (or 13% of all terrestrial habitats) established around the world. Cumulatively, these techniques should result in a conservative estimate--or a worst-case scenario--of how much the tourism industry actually contributes to avian conservation.

Revenue data were obtained from a variety of financial records published by individual parks and agencies. These allowed the researchers to calculate R, the proportion of park funding generated by tourism activity. This value was calculated across entire countries to account for the fact that conservation agencies often distribute funds to multiple different locations. However, the scientists also calculated what proportion of each individual park's revenue was generated by tourism. This was entered into a relatively simple equation (also incorporating data on the size of birds' global populations and the size of their populations within protected areas) that yielded T, the proportion of each bird species' global population that is protected by tourist activities.

(Flamingos feeding in Lake Nakuru, Kenya)

The financial contributions of tourist activities varied hugely between protected areas. Some sites received no revenue from tourism, while other sites were completely funded by visitors; R values generally fell somewhere between 5 and 80%. Private reserves were particularly likely to earn a substantial portion of their income from tourists. Protected areas in African countries had the greatest tourism support (36-81%), while those in the most developed countries had the least (generally <15%). The low R values calculated in more developed areas likely reflects the fact that the governments of these nations tend to subsidize conservation work with earnings from federal taxes, while developing countries tend to be much more reliant on tourism earnings.

Population data were not available for all 562 CE and EN bird species originally selected for the study, but the authors were still able to investigate trends associated with 131 local subpopulations of 91 species. Calculations revealed that tourist activities helped support the protection of anywhere from 0-64% of each species' global population. A handful of species were at either end of the tourism support spectrum, receiving either no help from visitor revenue (n = 9) or having over a fifth of their global population supported by tourism (n = 8); the bulk of species (n = 50), however, fell somewhere in between these two extremes. Notably, T was significantly greater for CE species than EN species, indicating that tourism revenues are extremely valuable for helping preserve the most at-risk birds.

 (Speckled mousebirds on Mount Kenya)

Overall, the study reveals a number of surprisingly low R and T values. While it may be tempting to interpret these as an indication that tourism revenue is not generally that significant, it is important to note that the researchers identified 41 species for whom >10% of the entire global population relies on tourism revenue; decreases in visitor spending could have catastrophic impacts on the protection of these birds. Perhaps even more importantly, the countries with the highest R values are developing nations that likely do not have alternative sources of funding to devote to conservation efforts. In these nations, tourism revenue is probably a lifeline not only to threatened bird species, but also the locals who make a living by catering to visitors. It is also important to keep in mind that ecotourism is still a growing industry, suggesting that, in some areas at least, R (and maybe also T) will continue to increase over time.

Of course, there are some drawbacks to relying on ecotourism to sustain conservation efforts. For one thing, an increased number of visitors can lead to a decreased quality of life for endangered animals, to the point that the gains in revenue may not actually lead to improvements in species numbers. Another issue is the unpredictable and volatile nature of the tourism market, which can be influenced by uncontrollable factors such as weather. In the future, the researchers hope to utilize more detailed and sensitive calculations that might potentially allow them to take these sorts of trade-offs into account in their models.

(Guillemots and razorbills in the Isles of Scilly, UK)

Perhaps a more important thing to focus on right now, though, is the authors' finding that 43% of their 562 focal species seem to exist wholly outside the boundaries of protected areas, and thus may receive no real conservation help at all. Of the species that are found in protected areas, there are a number that live in only a single preserve. Together, these results suggest that avian conservation efforts could be vastly improved, regardless of how they are funded. As we set out to rectify this problem, we might consider focusing on island habitats and wilderness areas found in South America; these are the two types of environment in which there appears to be the greatest need for increased habitat protection. As the authors point out, the large number of threatened animals living outside of formally protected areas also emphasizes the importance of generalized efforts to increase biodiversity, rather than action plans that are focused only on particular tracts of land.

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Steven, R., Castley, J.G., and Buckley, R. 2013. Tourism as a conservation tool for threatened birds in protected areas. PLoS ONE 8(5):e62598.

All photos by me; more can be seen on my flickr photostream.