In some ways, the picture of amphibian survival I’ve painted over the past few weeks is pretty grim: we know that species are disappearing around the world, in some cases faster than we can identify them; we know that disease is playing a role, as well as pollution and a changing climate; and we know that environmental degradation is a key issue. When you add these things together, it may seem like frogs and other amphibians are on a permanent downward slope.
But at the same time, scientists have learned that some species are more resilient to habitat degradation or pollution than others, that there are easy ways to make available habitat more suitable for specialist species, and that cooperative efforts to protect threatened species can have positive results. Over the last week, as I’ve searched for ways to help frogs through everyday actions, I’ve learned that there are many, many people who care about frog conservation, and that alone is a very positive thing.
What can we do as individuals? Quite a lot really, which is a comforting thought.
On your computer, one of the most important things is letting policy-makers know that amphibian protection is important to you. There are many organizations developing petitions that range from protecting a specific wetland area to banning harmful chemicals. Check out Save The Frogs to get some ideas and even sign a few.
In your backyard, there are many options for creating a more frog-friendly environment:
- Create an oasis for frogdom by having a frog pond- Australia’s RANA organization has guidelines on how best to meet amphibian needs for artificial bodies of water.
- Reduce your use of pesticides, herbicides, and fertilizers- remember that every time it rains, things in your soil get moved around and even washed away- all of those pollutants in the water supply have an impact on the health of the environment as a whole and water-dwelling species in particular- for tips on reducing use of chemicals, the US Fish and Wildlife Service has a pamphlet.
- Cut back on water use- those gallons running through your tap are often removed from natural water systems, which certainly doesn’t do the frogs any favors.
Farther afield, you can participate directly in frog conservation efforts:
- Help migrating amphibians get safely to their breeding sites- many are killed each year as they migrate across roads, but there are ways to reduce road-mortality. Push your community to locate important crossing points and install ‘toad tunnels’ that will keep amphibians out of harm’s way. You can also act as a crossing guard on peak migration nights in the spring- in NH’s Cheshire County, AVEO helps organize amphibian helpers, and other environmental groups provide the same leadership in different areas.
- Clean up urban sites- although you might not think of urban water sources as important habitat for amphibians, Garcia-Gonzalez and Garcia-Vazquez (2012) found that urban ponds in Spain had considerable species diversity and more genetic diversity within species when compared with rural ponds, so urban ponds could be very important for amphibian conservation in an increasingly urban world. You can help urban frog populations by removing trash and pushing for proper chemical disposal.
- Become a frog scientist- the Amphibian Specialist Group wants your help in cataloging the world’s species and developing records for abundance and geographic range- they want everyone to send in pictures when they see amphibians, whether or not you know what species it is. I don’t know about you, but my cell phone camera is easy to use and pretty portable.
So there are a variety of ways in which each of us can contribute to frog conservation. Whether we’d prefer to stay in the comfort of our homes, work in our gardens, or stand in the rain on a spring night, there are many options. Hopefully one (or more) of these ideas really appeals to you, and, at least where I am, spring is right around the corner- it’s a perfect time to get involved.
Works cited:
Garcia-Gonzalez, C. and E. Garcia-Vazquez. 2012. Urban ponds, neglected Noah’s Ark for amphibians. Journal of Herpetology 46: 507-514.
I have to say that frog researchers are doing, and have done, some pretty amazing things to learn more about the big issues facing amphibians and how we can improve their chances. (It would never have occurred to me that you could track frogs.) And their results are helping us better understand not only the suite of problems but also our options for alleviating them, which is great- all death and destruction and no chance for recovery makes any conservationist a bit depressed.
As I mentioned in my last post, environmental contaminants are negatively impacting frog species. Some of those pollutants come from agricultural practices, but others are connected to industrial production. Mercury has been known to bio-accumulate in top level predators like killer whales and swordfish (and us), and Loftin et al. (2012) found that it also bio-accumulated in wood frogs who hatched in ponds with high mercury levels. They hypothesized that water in the ponds had high levels of mercury from the presence of soft woods the surrounding area; the mercury was absorbed by algae and worked its way up the food chain to the frogs. They also thought that, when the young frogs dispersed from the ponds where they hatched, mercury could be spread to other locations. So what can be done? Well, reducing mercury emissions into the environment would help more than just the frogs, but since these mercury-frog hotspots are connected to a type of forest, we could also target mercury clean-up to ponds in soft wood forests (the Lofkin article explains why soft woods are so important- basically it has to do with certain trees being better at taking in mercury and then shedding it in leaf litter) and perhaps even look at ways to increase the proportion of hard woods in certain places.
Compounds coming directly from us are also impacting frogs. You may have heard about fish and other aquatic species developing physical mutations as a result of exposure to human hormones, such as estrogen, in the water supply. It turns out that it’s about more than extra limbs or having both sex organs (which obviously are massive problems for the individuals involved)- there can also be changes we can’t necessarily see, but certainly hear. In Germany Hoffmann and Kloas (2012) recorded the mating calls of male Xenopus laevis both before and after exposure to 17α-ethinylestradiol (commonly found in contraceptives)- when they played the calls for female frogs, the females were much more attracted to the calls before exposure (which were more frequent, less raspy, and had more clicking sounds). More than 4 weeks later, the calls from exposed males were still impacted! So, males exposed to the types of estrogen compounds found in contraceptives (and subsequently in water coming from human populations) are at a reproductive disadvantage, and that could have real implications for the future of any species.
A lot of the research published last year focused on how Bd works and why it has catastrophic consequences in some areas and not others. Voyles et al. (2012) investigated how Bd changed body chemistry in mountain yellow-legged frogs in California- the fungus altered fluid and electrolyte levels, for example sodium and potassium, which could lead to dehydration and even cardiac arrest. By knowing how the pathogen causes death, scientists can better develop ways to mitigate its impact. (As a side note, if you want to get a visual sense of just how quickly Bd can knock out a population, check out the maps in this article- it’s horrifying.) In looking at frog populations in New York, Becker et al. (2012) found that the sensitivity of Bd to temperature (its optimum range is 17-25 °C) translated into greater infections when canopy cover over temperate ponds kept the water cooler- so perhaps one strategy for combatting the disease is creating enough breaks in the vegetation hanging over ponds to ensure that frogs, and other amphibians, have enough shallow, warm water.
What else can be done to support frog populations? Since habitat loss is the overarching issue facing amphibians, Puglis and Boone (2012) looked at ways to make what green space is available in suburban and urban environments more frog-friendly. They found, for example, that amphibian survival on golf courses was considerable, and that sensitive species, such as cricket frogs, preferred taller grass vegetation. Since there are over 17,000 golf courses in the US, adding an un-mown buffer area around ponds on those courses could create better habitat for local amphibians. Humphries and Sisson (2012) investigated habitat use by gopher frogs in North Carolina and highlighted the importance of thinking on bigger scales with species that have to migrate to and from breeding sites. (And they used transmitters to do this- brilliant! If you are as curious as I was about how to put a transmitter on a frog, check out this picture from National Park Service research in the Rocky Mountains.) Since their animals migrated up to 3.5 km (!), protecting gopher frogs means protecting more than just the ponds they breed in. Additionally, since frogs tend to be away from water sources during migration, they are very vulnerable to fire, so prescribed fires should be limited to periods when frogs have reached their summer sites.
I feel that the takeaway message from this recent research is that, yes, frogs are in trouble, but we can help. Many of the ideas mentioned above for supporting amphibian populations are more system-wide actions and may not be accessible to us as individuals, but surely there are ways that we can contribute. For my next post, I’ll do my best to dig up small-scale options for our daily lives.
Works cited:
Becker, C.G., Rodriguez, D., Longo, A.V., Talaba, A.L. and K.R. Zamudio. 2012. Disease risk in temperate amphibian populations is higher at closed-canopy sites. PLoS ONE 7: e48205.
Hoffmann, F. and W. Kloas. 2012. Estrogens can disrupt amphibian mating behavior. PLoS ONE 7: e32097.
Humphries, W.J. and M.A. Sisson. 2012. Long distance migrations, landscape use, and vulnerability to prescribed fire of the gopher frog (Lithobates capito). Journal of Herpetology 46: 665-670.
Lofting, C.S., Calhoun, A.J.K., Nelson, S.J., Elskus, A.A. and K. Simon. 2012. Mercury bioaccumulation in wood frogs developing in seasonal pools. Northeastern Naturalist 19: 579-600.
Puglis, H.J. and M.D. Boone. 2012. Effects of terrestrial buffer zones on amphibians on golf courses. PloS ONE 7: e39590.
Voyles, J., Vredenburg, V.T., Tunstall, T.S., Parker, J.M., Briggs, C.J. and E.B. Rosenblum. 2012. Pathophysiology in mountain yellow-legged frogs (Rana muscosa) during a chytridiomycosis outbreak. PLoS ONE 7: e35374.
What combination of threats faces this tropical amphibian?
I’ve spent the last few days trying to get a sense of how frogs are faring around the world, and what I found was generally depressing- according the to the first Global Amphibian Assessment which was completed in 2004, at least 43% of amphibian species are in decline worldwide (Ben-Ari 2005). This trend seems to have gained momentum over the last few decades, and scientists are investigating a wide variety of possible causes, including habitat loss, global climate change, environmental pollution, and disease. One of the things that amazed me was how quickly populations could be lost in some cases- with the golden toad and harlequin frog in Costa Rica, for example, populations that had seemed healthy in 1987 were all but gone a year later (Pounds and Crump 1994). To put that in perspective in terms of my life, it was as if the town of 2000 that I grew up in was reduced to a single person in the space of 12 months- that’s horrifying. Why should we pay attention to this? Well, frogs and other amphibians are sensitive to changes in their environment, so their demise could very well be pointing to changes that are negatively impacting all of us; and the loss of frogs and tadpoles changes ecosystem processes, for example by allowing more algae to grow or more mosquitos to survive (Norris 2007).
Is habitat loss the key? It’s definitely a major player. Habitat loss seems to be central to frog declines worldwide (Lips et al. 2005, Puglis and Boone 2012). When Davidson et al. (2001) looked at the decline of the California red-legged frog which had disappeared from more than 70% of its CA range, they found that habitat loss was one of the most important factors, especially with regard to urban development. And it’s not just the issue of more roads and parking lots and houses- other habitat alterations are creating consequences you might not expect. 14 sites in Brazil were surveyed before and after the reservoir for the Serra de Mesa dam was flooded (Brandao and Araujo 2008)- after three years, 8 of 19 frog species along the edge of the reservoir had disappeared from the area and only 1 species remained on the islands in the reservoir. Now, we might think that expanding the amount of water available to frogs would help them, but hydroelectric flooding tends to create deep bodies of water with less shallow habitat for frogs and tadpoles, waves that can disturb eggs, and a line of dead vegetation along the water’s edge, all of which create problems for frogs.
Climate change is also altering frog ecology. Rising global temperatures are leading to earlier mating among frogs. When researchers compared data from Ithaca, NY for 1900-1999, they found that 4 of 6 target species initiated breeding at least 10 days earlier (Gibbs and Breisch 2001). Researchers in Poland also found that body size was increasing among some species, they believe as a result of warmer temperatures and greater insect populations (Tryjanowski et al. 2006). While this might seem like a positive development in terms of competition for resources, since females of one species preferred smaller males, it may impact breeding success in the future. One of the big concerns with climate change is also any alterations in moisture patterns, since frogs are so sensitive to this. Pounds and Crump (1994) felt that one of the factors leading to loss of the golden toad, among other species, in Costa Rica was decreased moisture as a result of stronger El Nino patterns.
And elements within ecosystems may be contributing to frog declines. According to Buck et al. (2012) 30-60% of shallow ground water and 60-95% of streams in the US contain pollution from at least one pesticide. Some pesticides, such as carbaryl (which is used on apples and cherries, among other things), were shown to delay metamorphosis in frog species. Pounds and Crump (1994) also suggested that climate disturbance may be interacting with atmospheric pollution to create toxic mist and clouds. One of the big areas of concern right now is disease caused by the (possibly) introduced fungus Batrachochytrium dendrobatidis. Bd has been implicated in continent-wide (as in Australia, and Central and South America!) amphibian declines (Norris 2007), and there are big questions about its role, for example why frogs in the northeastern US carry it with little impact (Gahl et al. 2011), but Panamanian populations have been heavily impacted (Lips et al. 2008).
So there are many factors and many questions regarding current amphibian declines. I’ve provided a brief overview here, but scientists are attempting to tease out the details and hopefully find ways to support frog populations and stop what seems to be a free-fall in some areas. In my next post, I’ll provide information on very recent research as well as possible responses from the scientific community.
Works cited:
Ben-Ari, E. 2005. A new piece in the puzzle of global amphibian declines. BioScience 55: 96.
Brandao, R.A. and A.F.B. Araujo. 2008. Changes in anuran species richness and abundance resulting from hydroelectric dam flooding in central Brazil. Biotropica 40: 263-266.
Buck, J.C., Scheessele, E.A., Relyea, R.A. and A.R. Blaustein. 2012. The effects of multiple stressors on wetland communities: pesticides, pathogens and competing amphibians. Freshwater Biology 57: 61-73.
Davidson, C., Shaffer, H.B., and M.R. Jennings. 2001. Declines of the California red-legged frog: climate, UV-B, habitat, and pesticide hypotheses. Ecological Applications 11: 464-479.
Galh, M.K., Longcore, J.E. and J.E. Houlahan. 2011. Varying responses of northeastern North American amphibians to the chyrtrid pathogen Batrachochytrium dendrobatidis. Conservation Biology 26: 135-141.
Gibbs, J.P. and A.R. Breisch. 2001. Climate warming and calling phenology of frogs near Ithaca, New York, 1900-1999. Conservation Biology 15: 1175-1178.
Lips, K.R., Burrowes, P.A., Mendelson, III, J.R. and G. Parra-Olea. 2005. Amphibian population declines in Latin America: a synthesis. Biotropica 37: 222-226.
Lips, K.R., Diffendorfer, J., Mendelson, III, J.R. and M.W. Sears. 2008. Riding the wave: reconciling the roles of disease and climate change in amphibian declines. PLoS Biology 6: e72.
Norris, S. 2007. Ghosts in our midst: coming to terms with amphibian extinctions. BioScience 57: 311-316.
Pounds, J.A. and M.L. Crump. 1994, Amphibians declines and climate disturbance: the case of the golden toad and the harlequin frog. Conservation Biology 8: 72-85.
Puglis, H.J. and M.D. Boone. 2012. Effects of terrestrial buffer zones on amphibians on golf courses. PLoS ONE 7: e39590.
Tryjanowski, P., Sparks, T., Rybacki, M. and L. Berger. 2006. Is body size of the water frog Rana esculenta complex responding to climate change? Naturwissenschaften 93: 110-113.
Rain forest frog we found in a pitfall trap in Bolivia
Where I am in Louisiana, spring is already in full swing- the tulip trees are blooming, song birds are loudly proclaiming their territories, and spotted salamander egg masses can be found in standing bodies of water. When some friends went looking for amphibians a week ago, they found lots of croaking frogs. Over the last few weeks, I feel like the plight of frogs around the world keeps appearing in front of me- in things I read, in classes, in discussions, frogs seem to be trying to get my attention. And it seems like a seasonally-timely topic since, over the next few months, many of you will be in the midst of spring amphibian migrations.
My knowledge of frog and toad is ecology is pretty basic, and I have a general sense of the problems they are facing around the world. I know that frog populations are declining in a wide variety of places, and scientists aren’t sure if there is one large pattern or several factors in different locations. I’ve heard of fungal pathogens, chemical toxins, and habitat loss- because frogs, and other amphibians, have such permeable skins, they may be more sensitive to pollutants and pathogens in the environment, making them early-warning signals for ecosystem problems. There is additional concern about frog populations because diversity is high in tropical areas and current rates of habitat conversion may outpace our ability to identify all species before they disappear.
Amphibians are pretty amazing animals, and, in some ways, they represent the evolutionary qualities needed for life to colonize land. They also tend to be less visible than other forms of terrestrial life because they are smaller and often are camouflaged, so I think that sometimes we don’t think about their presence and contributions to the ecosystems around us; but they have multiple roles in the environment, and the decline in worldwide frog populations may serve as a huge alarm bell for environmental problems that we may not even be monitoring yet.
So I think it’s very important to pay attention to frog, toad, and other amphibian populations around us, but I’m not quite sure what most to be concerned about or how local trends are connected. I’m also not sure how best to support amphibian populations, so this month I’m going to focus on frogs and their kin. I’ll probably jump from place to place, but hopefully I’ll find some overarching trends and ways to get involved.
Recycling unused materials cuts back on resource use (just imagine what could be made out of these)
In my last post I looked at larger, systems-wide options for reducing greenhouse gas emissions, but those actions may not be possible where you live, or it may require some time to move down those roads. I’m not sure how much time we have to prevent certain climate change effects, and I personally feel better when I can take specific steps to reduce my contribution to greenhouse gas emissions, but learning how best to do that can require a lot of searching. I was disappointed at times with the information that wasn’t easily accessible, and, if I had a quarter for every time I saw the words ‘carpool’, ‘CFL lightbulb’, and ‘recycle’, I could probably buy enough carbon offsets to equal my entire footprint- surely there are other things we can be doing in addition to the big three mentioned above.
How can we be better shoppers?
- At the grocery store, look for paper products that don’t use old-growth wood, since use of old-growth forests a) releases a lot of stored carbon back into the atmosphere, and b) alters habitats that are becoming rarer; choose fewer processed foods since those require more energy to create; buy local foods that don’t have to be transported large distances; and look for environmentally-friendly cleaning products (check thedailygreen.com for a review of those options).
- If you’re thinking of getting a new computer or tv, check out Greenpeace’s ‘Greener Electronics’ rankings (I was very happy to see that my laptop had been a good choice, but they didn’t have my cell phone manufacturer listed).
- When choosing a supermarket or airline or other product/service provider, consider the effect that they have from an environmental and social perspective- greenamerica.org’s Responsible Shopper ranks different companies based upon these criteria and assigns grades for several categories- they don’t always have environmental data for each company, and they don’t list all companies, but it’s a good starting point.
- Think about product longevity– rather than looking for the newest version or the cheapest option, look at what will meet your needs for the longest period of time- and push manufacturers to make longer-lasting goods. Imagine what could be conserved if buttons on remotes were more durable or mechanical pencils contained more graphite.
Let’s think outside the box when it comes to reducing our impact on the environment- when you look at the Eden project today, you wouldn’t know it’s built on the remains of a clay mine
Life-style changes
- Norman et al. (2006) found a significant difference between the energy needed to construct and operate single-family houses and multi-unit buildings. Not everyone wants to live in an apartment building, but even the difference between duplex and detached homes could be important. Within housing construction itself, the drywall and bricks used seemed to contribute a large proportion of energy use and greenhouse gases, so alternative materials may be helpful.
- Hybrids do help- when Samaras and Meisterling (2008) compared the lifecycle emissions from conventional, hybrid, and plug-in hybrid vehicles, hybrid vehicles reduced emissions by more than 30% when compared with conventional vehicles. Plug-in hybrids, which combine a hybrid vehicle with the ability to get electricity directly from the power grid, reduced emissions even more, although the degree was dependent on what powered the electrical grid and how the batteries were manufactured.
- Reconsider what and how much you buy. The common refrain I heard was that the issue is not really what power sources we use, but simply the fact that we use so much, whether it’s for heating or transportation or to create the goods we buy (Van Putten 2008, Dodman 2009, ter Steege 2010).
It’s true that none of the above actions will create an immediate halt to global climate change, but the combined impact of each of us working to reduce our greenhouse gas emissions can influence the intensity and duration of what the world experiences. And I believe that it is far better to act now even if the outcome is not assured.
Works cited:
Dodman, D. 2009. Blaming cities for climate change? An analysis of urban greenhouse gas emissions inventories. Environment and Urbanization 21: 185-201.
Norman, J., MacLean, H.L., and C.A. Kennedy. 2006. Comparing high and low residential density: life-cycle analysis of energy use and greenhouse gas emissions. Journal of Urban Planning and Development 132: 10-21.
Samaras, C. and K. Meisterling. 2008. Life cycle assessment of greenhouse gas emissions from plug-in hybrid vehicles: implications for policy. Environmental Science Technology 42: 3170-3176.
ter Steege, H. 2010. Will tropical biodiversity survive our approach to global change? Biotropica 42: 561-562.
Van Putten, M. 2008. How to save a planet: a user’s guide. BioScience 58: 874-879.
As I started looking through literature on ways to reduce greenhouse gas emissions, it became clear that studies had approached the issue largely from two different angles: a) how specific industries are contributing to global warming in a broad sense, and b) how smaller-scale decisions, like those made by consumers, are involved. It made sense to continue this separation in my posts, so this week I’ll look at the larger-scale information, and in the final post of the month I’ll focus on things that I have considerably more control over, such as whether to get a hybrid for my next vehicle.
The power source for this factory emits greenhouse gases and other things
Fossil fuel use is the biggie, and, unfortunately, continuing to get bigger. According to Meinshausen et al. (2009), there was a 20% increase in CO² emissions from fossil fuel use between 2000 and 2006 alone (ouch!). When talking about stabilizing CO² concentrations in the atmosphere at low levels, van Vuuren et al. (2007) concluded that we’ve already passed or are close to passing those goals, so we would need to use an ‘over-shoot’ strategy in which we not only stop adding to the CO² in the atmosphere, but also start removing it. That seems like a tall order. What are our options for reducing emissions from fossil fuels? When we talk about fossil fuel use, we’re talking about energy production for the most part, whether that’s power to light our homes, power to run our cars, power for factories, or other uses. Not all fossil fuels are the same when it comes to emissions- natural gas, for example, burns cleaner than coal, so greater use of gas in power plants could be helpful toward our goals for emissions reduction; however, gas, like all fossil fuels is a limited resource and getting access to harder-to-reach deposits is a challenge which will continue to grow as we consume more accessible supplies. Fracking is one option for getting to smaller, scattered deposits, but around 5 million gallons of water are needed for each well’s fracking fluid (Black and Ladson 2012), and water is also becoming an ever-more precious resource.
Some have suggested biofuels as our best option for reducing our emissions since so much of what we do depends upon combustion. Not all biofuels are equal, however, nor is current production nearly enough to satisfy worldwide demand- according to Nash (2007), in 2007, even if all soybeans and corn grown in the US had been made into biofuel, it would only have provided 6 percent of the diesel and 12 percent of the gasoline needed. (And there is a HUGE debate raging over the ethics of using agricultural land for biofuel production when doing so will impact global food prices and/or cause much more land to be put into agricultural use thereby reducing other types of habitat [Nash 2007; van Blottnitz and Curran 2007; Borjesson 2009; ter Steege 2010].) When biofuel sources and processing methods are compared, some types seem to be better than others with regard to emissions. Sugar-based bio-ethanols, especially those using sugar cane, are more efficient at energy-conversion (van Blottnitz and Curran 2007) than other types of bio-ethanols. Biodiesel production has fewer emissions and greater energy return than bio-ethanol (Nash 2007). One of the biggest contributors to emissions during biofuel production is the energy source used for processing. In the US and most of northern Europe, coal and gas are used in biofuel plants (Borjesson 2009); in Sweden, however, the use of biomass as an energy source in grain-based bio-ethanol significantly reduced emissions. Emissions can be reduced even more if you piggy-back processes- for example, if there is a sugar-processing plant already in existence, and then you use the excess steam to power fermentation of the waste products, you are essentially producing bio-ethanol without additional emissions. And some promising research by David Tilman at the University of Minnesota suggests that native prairie grasses may be able to provide both efficient sources of cellulose ethanol and habitat for native species- that’s a pretty cool win-win if it can be implemented on a large scale.
love highland cattle, but not the methane they produce
What about emissions from agriculture in general? As I mentioned before, livestock husbandry is a source of methane, both from ruminants such as cows and manure in general. In 2006 Monteny et al. suggested that several options existed to reduce methane emissions, although some might be more practical than others: a) adding sugars and reducing fats in ruminant diets; b) giving dairy cows a longer lifespan so that a smaller proportion of their lives is spent in growth, when they produce methane but no milk; c) deep cooling of and frequent addition of straw to manure; and d) use of methane as a biogas through controlled storage of manure. Other agricultural activities, especially those that use machinery, contribute to greenhouse gas emissions; while cutting out machinery may not be an option, there are ways to counterbalance emissions: reduced-plowing or no-tillage practices help soil carbon stocks develop, removing CO² from the atmosphere; allowing un-used land to reforest also creates a CO² sink; and the development of reduced-emission products for agricultural use cuts back on CO² before it gets to the atmosphere (Adams et al. 1996).
All of the information above deals with systems-wide practices and options, which isn’t always applicable to our daily lives. I do, however, think it’s very important that we know how participation in these larger systems impacts greenhouse gas emissions. We may be able to make choices about where our power comes from, for example, selecting a biomass plant over a coal plant. We may also be able to push for changes in the way that biofuels are produced, and we can look for agricultural products that are produced with an eye to reduced emissions- maybe there is a dairy near you that uses methane as biogas- it might be worth becoming a customer to keep the system going.
It’s no good saying that these issues are much too big for us to influence- maybe change will be incremental, but it’s still change. However, I recognize that it’s affirming to see more immediate results from our actions, so next week I’ll look at smaller decisions we can make to reduce greenhouse gas emissions.
Works cited:
Adams, D.M., Alig, R.J., McCarl, B.A., Callaway, J.M. and S.M. Winnett. 1996. The forest and agricultural sector optimization model: model structure and applications. USDA FS Research Paper PNW-RP-495, Portland, Oregon.
Black, B. and M. Ladson. 2012. The legacy of extraction: reading patterns and ethics in Pennsylvania’s landscape of energy. Pennsylvania History 79: 377-394.
Borjesson, P. 2009. Good or bad bioethanol from a greenhouse gas perspective- what determines this? Applied Energy 86: 589-594.
Meinshausen, M., Meinshausen, N., Hare, W., Raper, S.C.B., Frieler, K., Knutti, R., Frame, D.J., and M.R. Allen. 2009. Greenhouse-gas emission targets from limiting global warming to 2° C. Nature 458: 1158-1163.
Monteny, G-J., Bannick, A. and D. Chadwick. 2006. Greenhouse gas abatement strategies for animal husbandry. Agriculture, Ecosystems and Environment 112: 163-170.
Nash, S. 2007. Decrypting biofuel scenarios. BioScience 57: 472-477.
ter Steege, H. 2010. Will tropical biodiversity survive our approach to global change? Biotropica 42: 561-562.
van Blottnitz, H. and M.A. Curran. 2007. A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective. Journal of Cleaner Production 15: 607-619.
van Vuuren, D.P., den Elzen, M.G.J., Lucas, P.L., Eickhout, B., Strengers, B.J., van Ruijven, B., Wonink, S. and R. van Houdt. 2007. Stabilizing greenhouse gas concentrations at low levels: an assessment of reduction strategies and costs. Climatic Change 81: 119-159.
I think it should be pretty clear that researching the state of the atmosphere is a tall order- and some journal articles go REALLY in-depth when it comes to chemical reactions and composition and simulations (after a while, I found my eyes glazing over anytime I encountered more than 2 pages of graphs)- but I felt that I needed to start with some basics about the make-up of and recent trends for our atmosphere. And although I’m sure this is not a complete account, I do think that I have a sense of how things have changed with regard to greenhouses gases and how those changes seem likely to impact us. (I feel I should point out that some models have so many variables that the magnitude of impacts can be hard to gauge- however, everyone seemed to agree that change is in the air.)
Overlooking the busy streets and canals of Copenhagen
Which gases are scientists concerned about and how have levels changed? Some studies took a broader view than others, but the big players seem to be: Carbon dioxide, which we tend to hear the most about since we have been so good at producing it since the Industrial Revolution- a 1976 review of air pollution sources and emission rates found that CO₂ levels in the atmosphere had increased by 9% from 1860 to 1969 (Bach 1976). That level increase was supposed to be 15% by 1979 and 23% by 1989- in other words, not only are we putting extra carbon dioxide into the atmosphere, but we are putting it in faster and faster. In 2004, Hansen and Sato calculated that the rate at which CO₂ is increasing had doubled between 1950 and the 1970s and fossil-fuel emissions themselves had more than quadrupled in the previous 50 years. Why is this important? Carbon dioxide helps trap heat within Earth’s atmosphere and contributes to global warming. According to Hansen and Sato (2004), 9 years ago, we were already reaching a point where CO₂ emissions would put us past the 1° C warming mark.
Methane is another big concern. Although we produce less methane, this gas is getting a lot of attention for several reasons. Atmospheric methane levels increased 1-2% per year through the mid-1980s (Wang et al. 1986), and much of that came from human activity (the biggest sources of methane include ruminants, such as the cow used for your hamburger than can produce around 200 L of methane each day (Cicerone and Oremland 1988), rice paddies where water-logged conditions facilitate anaerobic decay, and burning of biomass, such as when forests are cleared). Why is methane important? Methane (CH₄) is a thicker gas than CO₂ so it heats the atmosphere more (Guthrie 1986). It also takes longer to remove methane from the atmosphere (Hansen and Sato 2004) which increases its heating potential more. In addition, some methane is currently held in solid form under permafrost and ocean sediments, especially in the Arctic region (Harvey and Huang 1995). Global temperatures are expected to experience the greatest rise at high latitudes (Schuur et al. 2008), and that methane could be released into the atmosphere where it would intensify heating effects. One of the big concerns here is positive feedback– temperatures get warmer, so more methane is released, so temperatures get even warmer; more CO₂ means higher temperatures and more plant growth, more plant material means more methane-producing decomposition, and more methane adds to the rise in temperatures.
A quick shower gives way to clearer skies over Edinburgh
Scientists are also keeping an eye on several other gases, such as nitrous oxide (N₂O) which has been increasing at about .25% per year (Wang et al. 1986) and comes largely from bacterial and combustion (here, read ‘coal’) processes, but may also be increasing as a result of positive feedback from global warming (Hansen and Sato 2004). Nitrogen oxides are also released through combustion and can increase solar absorption by the atmosphere where abundant, creating localized heating (Wang et al. 1986). Carbon monoxide, coming in part from our transportation options, is a concern because it can alter ozone concentrations.
Are there any bright spots? Yes, to a certain extent. Harvey and Huang (1995) felt that, even under a worst-case scenario of methane clathrate release, the impact wouldn’t be as intense as the difference between their low, middle, and high CO₂ scenarios. And thanks to international regulations and cooperation, atmospheric CFC levels started declining in 2003 (Hansen and Sato 2004). Hansen and Sato (2004) also felt that coordinated efforts to reduce methane emissions could help counteract global warming caused by CO₂.
But our options may be diminishing. While in 2004 Hansen and Huang were concerned with 1° C further rise in temperatures (creating a total of 1.5° C since 1900), in 2009, Meinshausen et al. assessed our options for limiting global temperature change to 2° C- this may be a moving target. I do believe that it is possible to limit our emissions and I also think that individuals, acting in concert, can make a big difference here, but we don’t always have the information needed to make the best choices. Over the past few years, many studies have concentrated on precisely where greenhouse gases are coming from, not just by industry, but by specific product and from start to finish. It seems to me that this is exactly the kind of information that would be useful to us, but it’s not always easy to find. For next week, I’ll be looking at greenhouse gas emissions by fuel type and for specific goods that we use in our daily lives, trying to decipher how what I do in the course of a day impacts the atmosphere.
In this case, information is power- and we may discover that we have more options than we thought for creating positive change.
Works cited:
Bach, W. 1976. Global air pollution and climatic change. Reviews of Geophysics and Space Physics 14 (3): 429-474.
Cicerone, R.J. and R.S. Oremland. 1988. Biochemical aspects of atmospheric methane. Global Biogeochemical Cycles 2: 299-327.
Guthrie, P.D. 1986. Biological methanogenesis and the CO₂ greenhouse effect. Journal of Geophysical Research 91: 10,847- 10,851.
Hansen, J. and M. Sato. 2004. Greenhouse gas growth rates. PNAS 101: 16109-16114.
Harvey, L.D.D. and Z. Huang. 1995. Evaluation of the potential impact of methane clathrate destabilization on future global warming. Journal of Geophysical Research 100: 2905-2926.
Meinshausen, M., Meinshausen, N., Hare, W., Raper, S.C.B., Frieler, K., Knutti, R., Frame, D.J., and M.R. Allen. 2009. Greenhouse-gas emission targets from limiting global warming to 2° C. Nature 458: 1158-1163.
Schuur, E.A.G., Bockheim, J., Canadell, J.G., Euskirchen, E., Field, C.B., Goryachkin, S.V., Hagemann, S., Kuhry, P., Lafleur, P.M., Lee, H., Mazhitova, G., Nelson, F.E., Rinke, A., Romanovsky, C.E., Shiklomanov, N., Tarnocai, C., Venevsky, S., Vogel, J.G., and S.A. Zimov. 2008. Vulnerability of permafrost carbon to climate change: implications for the global carbon cycle. BioScience 58: 701-714.
Wang, W-C., Wuebbles, D.J., Washington, W.M., Isaacs, R.G., and G. Molnar. 1986. Trace gases and other potential perturbations to global climate. Reviews of Geophysics 24: 110-140.
As 2013 begins, I’ve been mulling over events from last year and decisions to be made in the next 12 months, some of which involve things like energy sources and new places to live and even automobiles. And I’ve been hearing a lot about alternative energy and fracking and average temperatures, among other topics. I try to make good environmental choices in my daily life, but sometimes I feel like it’s difficult to find the information you need in order to make good choices. I feel pretty confident that I know some of the things to look for when I’m at the grocery store, and I realize that a general reduction in use of energy and ‘stuff’ is bound to be helpful, but what about other situations, for example with clothing or electronics or roofing materials?
Is this beautiful sunset caused by water vapor in the air or dust or something man-made?
We hear often about greenhouse gases and efforts to reduce emissions; I’ve come across comparisons of methane and carbon dioxide, but I feel uninformed in general about the state of our air and how I can directly help to improve it. How do pollution levels today compare with those from the last several decades? Where are the hot spots? When I breathe in, how much of what I inhale is man-made? If we take my heating and driving out of the equation, what are the biggest ways that I contribute to poor air quality and high levels of greenhouse gases? When I hear comparisons of oil and gas emissions, do those include all aspects of production or just the final step of heating my home?
In 2013 I’ll be moving south to a more urban location, which should offer opportunities to reduce my footprint, but it would be great if I had ideas beyond ‘take the bus.’ And I’m pretty sure I’ll be getting a new car at some point- obviously, I’ll look at gas mileage, but are there other considerations I should know about? And as much as I depend upon it every moment of every day, I know that I don’t pay nearly the same attention to the state of the atmosphere as I do to the oceans and landmasses.
So my resolution for this year has two parts, both of which will figure into this month’s posts: 1) I want to be more informed about how I can change the way in which my daily activities impact the planet, and 2) I want to give the air I breathe the attention it deserves. This month I’ll be concentrating on the latter, especially the issue of greenhouse gases and my personal contribution to them. If, like me, you feel that you don’t always know how to make the best environmental choices when it comes to the atmosphere, hopefully I’ll be able to give you a place to start.
Dingo (Canis lupus dingo)
Over the past few weeks, we’ve seen that dingoes play a variety of roles in the environment, and the extent and importance of those roles is hotly debated by researchers. Dingoes may help native wildlife by keeping exotic predator numbers down, but they may also prey upon threatened species in Australia. Dingoes are apex predators who can regulate herbivore numbers and therefore their presence may be worth protecting, but, if they are hybridizing with feral dogs, how can we be sure that true dingoes are being protected? Given the number of questions here, questions which in many ways are applicable to wild dog species around the world, it seems that more research is needed. However, some studies can take years or even decades, and that may be too long to maintain stable dingo populations in some areas. I think that a two-pronged approach is needed here and with other canids, and I think it will take direct action on the part of private individuals to move this process along.
Getting the data we need. (And please feel free to substitute ‘wolf’, ‘dhole’, ‘wild dog’, etc. for ‘dingo’ as you read through this post- you may not live near dingoes, but there probably is a wild dog that was/is present in your area.) A large part of unraveling the dingo problem is figuring out how these animals fit into various ecosystems, and that means conducting research, but the dingo occupies an interesting space within Australia’s laws and regulations, so doing research can be a bit complicated. I think that landowners in areas where dingoes have some level of protection should offer scientists the opportunity to conduct studies on their property if it does not directly endanger themselves or their neighbors. Contacting surrounding universities would be a good place to start the process- sometimes researchers have a great plan but are still looking for the right location- the Works Cited section in previous posts mentions student thesis at several universities, including the University of Western Australia and the University of Adelaide. The research process could benefit from changing the status of dingoes in Australia. The Australian Dingo Foundation has put together a petition to give protection to dingoes at a federal level, which could then be used by landowners who wanted to challenge the requirement that they kill dingoes on their property. There is no doubt that changing the way dingoes are managed has some risks- and particular attention needs to be paid to areas where remnant populations of native species exist, since those small groups, even if not heavily predated by dingoes, may not be able to withstand even small increases in predator populations- but after reading Wallach (2011), I do believe that current practices are not getting the large-picture results that people want.
Restoring apex predators. I think that people tend to view carnivores, especially those bigger than a house cat, with an element of fear, and that can make the discussion of coexistence more complicated. But larger predators have evolved into critical parts of ecosystem processes that help regulate prey and smaller predators- removing them from the system can cause a wide variety of problems. (And lest you think that I’m all about dogs, mountain lions started avoiding the growing number of human visitors to certain sections of Zion National Park, and mule deer quickly realized that those areas were now safer places to hang out (Ripple & Beschta 2006). Because the deer could congregate in those locations indefinitely, they over-browsed cottonwood trees- the result was stream bank erosion and fewer aquatic and terrestrial species overall. Mountain lions can be dangerous, but they also help provide balance.) I do think we need to reassess the way that we try to keep larger carnivores away from us- maybe we feel better about hiking or letting our kids and pets play outside, but we’re altering the ecological webs around us. And I think that predator re-introduction, especially in areas where smaller exotics are wreaking havoc, needs to be an option. I’m not saying that there should be a huge release of lions and tigers and bears (oh, my!), but I do think that there should be planned reintroductions in specific locations (with the understanding that populations do spread) and changes to the way that numbers are controlled in other locations (if baiting kills indiscriminately and may cause population instability which can lead to more problem animals, what about contraceptives to keep numbers down without breaking up packs?). And I’m not alone in my interest in re-introduction- in addition to ideas for dingo re-introduction, groups are working to restore wolves to a variety of habitats (check out the Maine Wolf Coalition for one example).
Education and public involvement is important. Helping people understand that predators can have positive impacts on the environment is a huge part of creating a balanced discussion- I’m not advocating for wild dogs at the expense of humans, but it shouldn’t be the reverse either; we’re all in this together. And since so many of these species are regulated, one way or another, at the state and federal level, politicians need to hear that there is a discussion and that there are a variety of options available. So it really is up to us to speak out, both about carnivore roles and the visions that we have for conservation work. I’m not expecting everyone to say the same thing, but maybe we can find some common threads for a starting point.
Other sites you might be interested in:
Photographers for Conservation– with the understanding that so little is known about some species and sometimes photos alone represent a leap forward in information, this group has launched specific projects to document species, including the dhole, so that the rest of the world can share the knowledge.
International Wolf Center– located in Minnesota, the Center focuses on carnivore education and works to further wolf re-introduction efforts. (They even have slumber parties!)
Wild Dog Foundation– this group is based out of NY and works to advocate for all wild dog species- it was hard to determine how active they are, but there is great background information about the different species.
Works cited:
Ripple, WJ & RL Beschta. 2006. Linking a cougar decline, trophic cascade, and catastrophic regime shift in Zion National Park. Biological Conservation 133: 397-408.
Wallach, AD. 2011. Reviving ecological functioning through dingo restoration. PhD thesis, School of Earth and Environmental Sciences, University of Adelaide.
Dingoes seem to be pretty controversial animals, and I think I even found about as close as you’ll get to a fight in the scientific community over the ecological roles of the dingo (what was fascinating about the exchange was not just what was said, but how it was said- scientists can be mean). A lot of the debate centers around whether dingoes are good for biodiversity and, especially, the preservation of threatened native species, or if they are disrupting ecological processes (I am sure that I haven’t even read half of the literature out there). And this discussion extends beyond dingoes to other wild dogs around the world.
Dingo (Canis lupus dingo)
What does the dingo data say? Dingoes have a diverse diet, as I mentioned before- one study found at least 29 native and 4 introduced prey species in dingo scat (Vernes et al. 2001); at least three species that dingoes prey on are threatened (Allen & Leung 2012). However, Pavey et al. (2008) found that dingoes put less pressure on rodent populations than red foxes and house cats, data echoed by Cupples et al. (2011) who found that red foxes preyed upon small mammals more than would be expected based upon their availability, while dingoes did not. Additionally, it appears that dingoes may help keep red fox numbers down- Johnson & VanDerWal (2009) found that foxes were rare where dingoes were prevalent, and Lu (2011)’s study only detected foxes in areas where dingo control was practiced. A similar situation was noted with feral cats in northern Australia (Kennedy et al. 2011). How does that impact biodiversity? To a large degree, the declines seen in Australia’s medium and small mammals since European colonization have been driven by introduced red foxes and house cats (Pavey et al. 2008; Johnson & VanDerWal 2009)- if the presence of dingoes can reduce fox and cat numbers, that should be good for Australia’s remaining small and medium-sized mammals. Ritchie & Johnson (2009)’s review of predation studies in Australia indicated that native species whose populations overlapped with the current dingo range have survived better, and that certain species, such as the dusky hopping mouse, were only found where dingoes are abundant. They also referred to the loss of a rufous hare-wallaby population partly in response to control- when the local dingoes were eradicated by poison, foxes soon moved in and predated the hare-wallabies to extinction. This type of relationship may extend to small carnivores as well- there are concerns that the removal of dingoes from areas with tiger quolls could expose the latter to unsustainable pressure from foxes (Andrew 2005).
A new way of looking at dingoes. I’m not trying to suggest that dingoes do only good in the environment: they also eat threatened species, as well as damaging the livelihoods of sheep and cattle ranchers- in the Northern Territory alone, it’s estimated that dingoes cause $2 million+ in damages to the cattle industry each year (Parks and Wildlife Service of the Northern Territory 2011). But it seems that trying to control their populations through baiting and trapping doesn’t always have the intended consequences- yes, dingoes are killed, but that doesn’t necessarily translate into safer livestock and recovery for threatened species. I found an interesting PhD thesis that looked at how the dingo population responds to baiting and trapping, and then how those responses impact other species, and the paper got me thinking about dingoes in a different way. Wallach (2011) compared sites with control programs, without control programs, and where control programs had recently ended, looking partially at numbers but also at population structure. According to the paper, that second element is the most important in determining how dingoes interact with their environment. Why? Similar to wolves, in a dingo pack only certain members reproduce; however, when pack stability is disrupted through baiting and trapping, dingoes often respond by breaking into smaller groups and becoming more productive- yes, those extra dingoes continue to be killed, but, before they are removed from the system, their behavior changes in some respects. Smaller packs must look for easier-to-subdue prey, which does make livestock more appealing, and Wallach felt that higher livestock attack rates were a result of pack disintegration. Poisoning also tends to remove animals indiscriminately, so older individuals who have perhaps learned to stay away from humans are targeted just as much as younger animals without that knowledge. There is also the possibility that hybridization is a consequence of predator control- normally a dingo pack would not allow in a domestic dog, but, when population stability is lost, single individuals may mate with dogs. Finally, without stable packs which can limit smaller predators, such as foxes, and prey on larger herbivores, such as kangaroos, you can get growing populations of those animals who then overuse available resources. Why is this information important? Something that Wallach said suggested that we may need to alter how we assess dingo roles: “It is the pack that is the top predator, not the individual dingo (78).” So, if we want to really understand how dingoes impact their environment and have the potential for supporting biodiversity, we have to look at the pack as an organism, and we have to consider the idea that killing dingoes is not a solution to conservation problems. Wallach advocated restoring ecosystems through a combination of vegetation enrichment, supporting animals that are ecosystem engineers, such as those that dig burrows used by other species, and letting apex predators regulate the system from the top.
What does this mean for other wild dogs? Well, it really depends upon the species, but there are some ideas that extend to all of them. Certainly the idea of the pack as a predator is important. Pack-living allows African wild dogs to hunt large prey cooperatively (Woodroffe et al. 2007), and larger packs increase survival for pups over 9 months of age (Buettner et al. 2007). Dholes in Asia require large packs to support the large litters which result from their entirely meat-based diet (Kamler et al. 2012). What about small carnivore regulation? In general, studies have found data that supports the idea that large carnivores limit the numbers of smaller ones (Ritchie & Johnson 2009)- and typically an increase of apex predators by a certain number will have an even larger negative impact on the number of smaller predators. Wolves, for example, limit coyote numbers- wolves were eradicated from New Hampshire where I live, and coyotes are a recent addition to the fauna in NH. As I mentioned in posts regarding bobcats, coyotes can keep house cat populations down. So, I think that looking at predator and ecosystem conservation involves looking at predator social structure and which other predators might step into any void that is created.
Once again, this is a lot of information to process- dingoes seem to have important roles in Australian ecosystems, but teasing apart the different aspects is challenging, especially when threatened species and people’s livelihoods are involved. The same is true for other wild dogs around the world- think of the controversy about wolf reintroduction in Yellowstone or the worries about coyotes in urban areas. Living with wild dogs is a challenge, as is finding ways to look at predator ecology from a dispassionate viewpoint that includes all aspects. I have no illusions about my ability to do the latter, but I’m hopeful that more complete understanding of how dingoes and other wild dogs fit into environments will make me better able to assess where I fit in- if you are in the same position, I hope to suggest some options in my next post when I focus a bit more on the human element.
Works cited:
Allen, BL & LK-P Leung. 2012. Assessing predation risk to threatened fauna from their prevalence in predator scats: dingoes and rodents in arid Australia. PLoS ONE 7 (5): e36426.
Andrew, DL. 2005. Ecology of the tiger quoll Dasyurus maculatus maculatus in coastal New South Wales. MSc thesis, School of Biological Sciences, University of Wollongong.
Buettner, UK, Davies-Mostert, HT, du Toit, JT & MGL Mills. 2007. Factors affecting juvenile survival in African wild dogs (Lycaon pictus) in Kruger National Park, South Africa. Journal of Zoology 272: 10-19.
Cupples, JB, Crowther, MS, Story, G & M Letnic. 2011. Dietary overlap and prey selectivity among sympatric carnivores: could dingoes suppress foxes through competition for prey? Journal of Mammalogy 92: 590-600.
Johnson, CN & J VanDerWal. 2009. Evidence that dingoes limit abundance of a mesopredator in eastern Australian forests. Journal of Applied Ecology 46: 641-646.
Kamler, JF, Johnson, A, Vongkhamheng, C & A Bousa. 2012. The diet, prey selection, and activity of dholes (Cuan alpinus) in northern Laos. Journal of Mammalogy 93: 627-633.
Kennedy, M, Phillips, BL, Legge, S, Murphy, SA & RA Faulkner. 2011. Do dingoes suppress the activity of feral cats in northern Australia? Austral Ecology 37: 134-139.
Lu, A. 2011. Presence of the dingo (Canis lupus dingo) on risk sensitive foraging of small mammals in forest ecosystems. Independent Study Project (ISP) Collection Paper 1130.
Parks and Wildlife Service of the Northern Territory. 2011. A management program for the dingo (Canis lupus dingo) in the Northern Territory. Department of Natural Resources, Environment and The Arts.
Pavey, CR, Eldridge, SR, & M Heywood. 2008. Population dynamics and prey selection of native and introduced predators during a rodent outbreak in arid Australia. Journal of Mammalogy 89: 674-683.
Ritchie, EG & CN Johnson. 2009. Predator interactions, mesopredator release and biodiversity conservation. Ecology Letters 12: 982-998.
Vernes, K, Dennis, A & J Winter. 2001. Mammalian diet and broad hunting strategy of the dingo (Canis familiaris dingo) in the wet tropical rain forests of northeastern Australia. Biotropica 33: 339-345.
Wallach, AD. 2011. Reviving ecological functioning through dingo restoration. PhD thesis, School of Earth and Environmental Sciences, University of Adelaide.
Woodroffe, R, Lindsey, PA, Romanach, SS, & SMK Ole Ranah. 2007. African wild dogs (Lycaon pictus) can subsist on small prey: implications for conservation. Journal of Mammalogy 88: 181-193.
