In sixth grade, I went on a three-day field trip to Cuyahoga Valley National Park. While the trip was loads of fun and we learned a lot about the environment, the thing that stuck with me the most was this annoying song about watersheds. Naturally, when we started talking about watersheds and estuaries in class, the song came to mind (and wouldn’t get out of it). So I’ll share some new discoveries about estuarine populations while I’m humming.
As we progress to larger species in class, I find myself disregarding the smaller marine organisms, but the health of zooplankton is significant in estuaries. Research was conducted by David and eleven other researchers last year to determine if the unique habitat of estuaries caused a particular structure in zooplankton populations. Water samples were taken from the Gironde Estuary in southwest France to be analyzed. They found that the upstream-downstream gradient of the estuary related to the distribution of species while abundance within a set species had a trend with estuarine depth – subtidal versus intertidal. The intertidal zone is especially attractive to zooplankton due to food availability. With the numerous challenges to estuaries in mind, disruptions to these populations of zooplankton in the intertidal zone or the availability of food in this zone could have significant implications along the trophic cascade.
While considering the changes that estuaries undergo due to the challenges that they face, a bit of research about the adaptive abilities of Olympia oysters (Ostrea lurida) caught my attention. Low salinity concentrations is linked to climate change, so this was the major aspect of change in the ocean water that they considered. Bible and Sanford designed a fascinating study. They collected oyster offspring from the Tomales Bay and San Francisco Bay estuaries and raised them in the laboratory. A population of these lab-raised oysters were then placed in the bay they originated from and a second population was placed in the opposite bay. This was completed at three different sites, and at two of the three sites the “local population” oysters survived better, indicating estuary-specific adaptation. A similar experiment was completed with second-generation lab-raised oysters, and the results showed that the oysters descending from the estuary with the lowest salinity survived low salinity challenges in the lab more often than the other oysters. I found this research to be well designed. I hadn’t thought about this idea before, but this shows that we need to evaluate how populations are adapting to the challenges that their estuarine home is facing before we take extreme measures to restore the estuary to its original condition.
That’s all for now! If that wasn’t interesting enough, tune in next time for a song about something else.
Bible, J.M., Sanford, E. (2016). Local adaptation in an estuarine foundation species: Implications for restoration. Biological Conservation. 193, 95-102. <http://www.sciencedirect.com/science/article/pii/S0006320715301634>.
David, V. et. al. (2016). Estuarine habitats structure zooplankton communities: Implications for the pelagic trophic pathways. Estuarine, Coastal, and Shelf Science. Published online. <http://www.sciencedirect.com/science/article/pii/S0272771416300221>.