By Sydney Waloven
Most people are probably familiar with the cute, small, furry mammals known as otters because captive sea otter populations often serve to educate the public about local coastal habitats and greater conservation issues surrounding these species (Brennan and Houck 1996). For instance, if you’re from California you are probably more familiar with the sea otter since it is The Monterey Bay Aquarium’s most widely known furry friend. Unfortunately, the sea otter has been marked with the “Endangered” status on IUCN’s Red List, with a decreasing population. The IUCN’s Red List is used by many wildlife departments, conservation organizations, and government agencies to monitor and propel protection and conservation action for our biodiversity and natural resources. Like the endangered sea otters, the North American river otters are also placed on IUCN’s Red List with a “vulnerable” status. In contrast to the otter’s lovable nature, they face many anthropogenic threats. Some threats include habitat destruction, pesticide pollution from agricultural development, and overexploitation (IUCN Otter Specialist Group).
Species of conservation concern, like those on the IUCN’s Red List, are challenging to manage due to the difficulty associated with sampling individuals from small populations or populations of low-density. This lack of information creates uncertainty associated with providing protective measures and conservation plans for threatened and endangered species (Elith et al. 2006). To enable more effective protection of the habitats that these species reside in, we must improve our ability to detect certain species to better assess their distributions (Wilcox et al. 2013).
Environmental DNA (eDNA) sampling is an emerging tool in the fields of ecology and conservation used to infer the presence of a species during the recent past. eDNA is any DNA that can be sampled from the environment typically from water, sediment, or soil (Rees et al. 2014). Therefore, eDNA sampling does not need to be directly sampled from the target organism. eDNA sampling can be more efficient and sensitive at detecting low abundance species compared to traditional trapping and netting methods (e.g., Jerde et al. 2011). However, the knowledge surrounding the ‘ecology’ of eDNA (i.e. the origin, state, fate, and transport) is still poorly understood (Barnes and Turner 2016).
Due to the similarities to the sea otter’s habitat and lifestyle, the North American river otter can serve as a model species to study the ecology of eDNA of aquatic mammals; then apply it to conservation management. This aims to improve detection rates and sampling methodology. In a study by Port et al. (2016), eDNA was used to characterize the spatial trends in sea otters in Monterey, who are a keynote species vital to the health of the kelp forest ecosystems. My research aims to expand on these and determine whether the state at which eDNA is collected, the method of detection, and/or the season of collection plays a role in the detection rate of an organism. Applying this information from my research may improve detection rates for rare species and more generally help to contribute critical knowledge used in innovative new conservation efforts to protect our endangered and threatened biodiversity.
Citations:
Barnes, M. and Turner, C. (2016) The ecology of environmental DNA and implications for conservation genetics. Conserv Genet 17(1): 1-17.
Brennan, J. and Houck, J. (1996) Sea otters in captivity: the need for coordinated management as a conservation strategy. Endangered Species Update 13(12): 61-66.
Elith, J. et al. (2006) Novel methods improve prediction of species’ distributions from occurrence data. Ecography 29(2). https://doi.org/10.1111/j.2006.0906-7590.04596.x
Jerde, C. et al. (2011) “Sight-unseen” detection of rare aquatic species using environmental DNA. Conservation Letters 4(2): 150-157.
Port, J. et al . (2016) Assessing vertebrate biodiversity in a kelp forest ecosystem using environmental DNA. Mol Ecol 25(2): 527 541.
Rees, H. et al. (2014) Review: the detection of aquatic animal species using environmental DNA – a review of eDNA as a survey tool in ecology. J Appl Ecol 51(5). https://doi.org/10.1111/1365-2664.12306
Silva, P. (2020) IUCN Otter Specialist Group: North American river otter. http://www.otterspecialistgroup.org/newweb/otters/north-american-river-otter#sthash.6AG09f1c.MIAV7K9L.dpbs Accessed on April 7, 2020.
Wilcox, T. et al. (2013) Robust detection of rare species using environmental DNA: the importance of primer specificity. Plos One 8(3). https://doi.org/10.1371/journal.pone.0059520
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