Regime shift in the GoM
For the past two months, I have been interning with the EML. Mainly focusing on getting our Calanus finmarchicus model to work better; an investigation into the relationship between our model and the whale data revealed an interesting phenomenon. Below is a figure showing arrival dates (red line) versus departure dates (blue line) for Right Whales in Cape Cod Bay (CCB).
Interestingly, this figure shows that whales spent more time in CCB between 1998-2000 (an average of 103 days) versus time spent in CCB between 2002-2008 (just 41 days). Also, during the 1998-2000 time period, correlation plots (below) showing the strength of the relationship between the whale data and our model results in CCB show a strong correlation (the darker the color, the stronger the relationship with * symbols indicating a significant relationship). Plots showing the relationship after 2001 showed very little correlation.
Therefore, the relationship between our model and the whale data is significant during a time period when whales spent a lot of time in CCB. This regime shift is not a new discovery, and has, in fact, been linked to changes in zooplankton abundance, and ultimately changes in higher trophic levels (Pershing et al, 2005). It was very exciting to learn that this regime shift has been captured, at least partly, by our model.
Andrew J. Pershing, Charles H. Greene, Jack W. Jossi, Loretta O'Brien, Jon K.T. Brodziak, and Barbara A. Bailey. 2005. Interdecadal variability in the Gulf of Maine zooplankton community, with potential impacts on fish recruitment. ICES Journal of Marine Science: Journal du Conseil 2005 62(7): 1511-1523.
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