My South Slough REU partner Sofia Suesue and I started off our week by participating in South Slough’s annual “Slough-a-thon.” Anyone affiliated with South Slough could participate in a bike/run/paddle event. Sofia and I did the running portion, and got to run a 5k through the beautiful trails of South Slough reserve! Last week, I had a really fun time helping Sofia with her research project, which involves mapping an endangered plant species known as Chloropyron maritimus ssp. palustre, or Bird's Beak. This plant grows in salt marsh areas found on the banks of the estuary. We went to a site called Distant Water fleet on Friday, and were pleasantly surprised at how abundant the plant was at this location. Sofia is mapping areas of the plant and noting soil type, salinity, and other plants found with Bird's Beak, all factors that might dictate where the plant grows and how limited its distribution is. But the most exciting part of my week has been making progress on my personal research project! I have decided to look at interspecies predation between the three common crab species found in South Slough. One of the main limiting factors of green crab distribution on the Oregon Coast is proposed to be competition and direct predation from the established native populations of crabs that tend to grow much bigger than Carcinus maenas. Right now, green crabs are mainly found in the middle and upper Coos Bay estuary. But the lower estuary is thought to be a more favorable habitat for crabs, due to higher salinity and lower water temperatures. The native red rock crab, Cancer productus, is only found in the lower estuary, as this species is less tolerant of physical factors than the green crab and thus requires the more favorable habitat. Right now, it appears that C. productus is able to dominate the lower estuary and limit green crab distribution, because the abundance of C. productus, is negatively correlated with abundance of C. maenas in the lower Coos Bay estuary (unpublished data). Basically, in the lower estuary where there are more red rock crabs, there are less green crabs. A study has found that C. productus is much more likely to conduct direct predation on small and medium sized green crabs than on small and medium sized crabs of their own species (Hunt & Yamada, 2002). This reinforces the fact that the inverse population distributions is caused by predation from C. productus on C. maenas in the lower estuary. After learning about this, I started to wonder if the green crab will ever be able to spread to the lower estuary. I have decided to conduct a continuation of the previously mentioned study, to see if C. productus still prefers direct predation of small C. maenas when another native species, the Dungeness crab (Metacarcinus magister) is also present, or if the Dungeness provide equally favorable or more favorable prey. Depending on the preference of C. productus, this could allow a possible opportunity for the population of C. maenas to continue to increase and become established at sites where the three species overlap, if C. productus is more likely to predate on available M. magister instead of the green crab. I have been collecting crab species all week and have been able to set up my initial trials of the predation experiment.
2 Comments
Stan Heller
7/8/2019 03:51:29 pm
Sounds like an interesting project. Will it run 4 or 5 weeks?
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Steven
8/4/2019 07:22:33 pm
I too would also like to know if it will take 4 or 5 weeks?
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AuthorHi! My name is Renee and I am a rising junior at Muhlenberg College in Pennsylvania. I am a double major, studying Biology and Dance. I am so excited to be a part of the Oregon Institute of Marine Biology’s summer REU program and to work with Shon Schooler and the South Slough National Estuarine Research Reserve. Archives
August 2019
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