By: Dana Sackett
As an environmental scientist I can honestly say that I am very concerned for the future of our planet and ourselves. I cannot emphasize enough the reality of climate change, that it is human-caused (and therefore that we can do something about it), and that we definitely need to do something about it, lest we end up with a planet that is largely uninhabitable for our great-grandkids (think of a less intense version of our sister planet Venus). Also, while there are a large number of environmental issues that will come about as a result of climate change in our lifetimes the ones I would like to focus on today are drought and pollution. While these are typically separate topics, they can interact in important ways.
First off, drought (caused by decreased precipitation and/or increased evaporation) all by itself can be a daunting problem; just ask California which has been enduring severe drought conditions for several years (see here and here), the southeastern United States which is currently experiencing a serious wildfire (see here), or the western Untied States which has resorted to draining groundwater aquifers to meet water needs, a source that is not renewable at the rate it is being used, is causing the ground to sink, and is running out at an alarming rate (see here). Wildfires, decreased air quality (rain cleans the air), running out of water for agriculture, recreation or even drinking have become serious concerns for a number of states in the US. And if you think that is bad imagine how it is for the plants and animals that live in that dwindling water. Studies have shown that the stress of drought can have major impacts on the health of aquatic life (besides simply having no water to live in).
Fish health, in particular, can be measured in a number of ways, one of which is ‘condition’ or how fat or skinny a fish is. The reason this measure is so useful to identify health is because of bioenergetics. That is a fancy way to say the study of energy flow and energy budgets. Think of balancing a check book, you have to balance what comes in with what goes out. Energy is similar: fish eat food and gain energy to grow, avoid being eaten, find a mate, and to reproduce. So when a stressful drought situation occurs (shallower, warmer, and less oxygen rich water), energy is now required to deal with those stressors. This stress response takes energy away from those other measures, particularly growth, making for skinny fish. This also means that these stressed-out fish have less energy to use for immune response and defense to disease and contaminants, making these animals more susceptible to illness and death from waterborne pollutants.
Pollutants can compound drought stress because the little bit of water that is available may have unsafe levels of contaminants as a result of the drought. Water quality, an issue near and dear to any fish (and all of us that like to trust that our water supply is safe) can become a serious problem during severe droughts. The trouble is that water dilutes those contaminants in aquatic environments and groundwater. When that water starts to disappear during a drought, concentrations of those pollutants increase, degrading water quality. For aquatic life this can be a serious problem as they would already be under stress from drought conditions and susceptible to normal concentrations of pollutants.
When looking to the future, consider the world you would like your grandkids and great-grandkids to live in. If it includes a largely habitable planet, clean drinking water, clean air to breath, and healthy aquatic ecosystems, make sure our leaders know that combatting climate change is a priority.
Some excellent resources, reading material, and references for this article are below:
- To find out the current and future research priorities for fisheries science see this document put together by the American Fisheries Society: http://fisheries.org/policy-media/future-of-the-nations-aquatic-resources/
- To find out how bad the drought currently is in your area enter your zip code at the bottom of the the following page: https://www.drought.gov/drought/data-maps-tools/current-conditions
Dai A. 2013. Increasing drought under global warming in observations and models. Nature Climate Change. 3, 52-58. http://www.nature.com/nclimate/journal/v3/n1/full/nclimate1633.html
Barnett, T., R. Malone, W. Pennell, D. Stammer, B. Semtner, and W. Washington. 2004. The effects of climate change on water resources in the West: Introduction and overview. Clim. Change 62(1–3):1–11.
Bennotti MJ, Stanford BD, Snyder SA. Impact of drought on wastewater contaminants in an urban water supply. J Environ Qual 39, 1196-1200.
Bonga SE W. 1997. The stress response of fish. Physiol Rev. 77, 591-625.
Kjellstrom T and Weaver HJ. 2009. Climate change and health: impacts, vulnerability, adaptation and mitigation. NSW Public Health Bulletin 20, 5-9.
Matthews WJ, Marsh-Matthews E. 2003. Effects of drought on fish across axes of space, time and ecological complexity. Freshwater Biology 48, 1232-1253.
Tibbetts JH. 2015. Air quality and climate change: a delicate balance. Environmental Health Perspectives 123:A148-A153.