WHERE HUMANS AND NATURE COLLIDE

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.'



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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.'

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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.

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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.

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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.

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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.

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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.