Monday, November 1, 2010

Eelgrass communities - An update

I recently gave a brief project update to the gang. Here are the nuts and bolts of my undergrad thesis (I’ll try to stay brief):

-Eelgrass meadows are important. They provide habitat for dozens of fish and invertebrate species, stabilize sediment, and cycle carbon and nutrients. Meadows are found in shallow coastal waters on the East and West coasts of North America. Seagrass meadows are globally threatened.

-The community dynamics of eelgrass meadows in temperate zones are largely not understood. In tropical zones, there is evidence that seagrass is often the victim of coastal eutrophication.

-Gulf Islands National Park Reserve consists of several islands off the southern tip of Vancouver Island. The park was established in 2003 and has been collecting data on fish and invertebrate communities in eelgrass meadows in the park. Data is collected as part of the park’s ecological integrity monitoring initiative. Parks Canada has a mandate to ensure that the ecological integrity of park lands is maintained.

Here is a bit of footage from field sampling:

video

So what could be influencing community dynamics?

-Proximity to Fraser River estuary as well as cool nutrient rich summer upwelling which results in a temperature and salinity gradient across sites as well as summer eutrophic conditions.

-Recent El Niño/La Niña oscillations may be influencing community dynamics.

-Using published fish and invertebrate diet data, a food web will be constructed. I will then explore site differences in community structure and then attempt to determine if community dynamics as consumer or producer driven. Analysis will be done in R using RDA analysis.

At this point in the semester my “who eats who” section of the project is complete (graphical representation coming soon) and am currently beginning “real” data analysis—mostly fiddling in R, trying to determine how the community composition of the various sample site sites differ.

An interpretation of regression:

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