Posted by admin | 05.12.2011 | Conservation, Marine Science, Turtle Talk

Considering Climate and Chelonids

Few things compare to the sense of elation upon finding a fresh crawl and a new nest after a long beach walk along crowd-less beaches in the early morning. Part of the thrill is being part of a very special experience, especially since the events themselves are highly unpredictable. Uncertainty is an underlying theme in nature, and therefore in science too. So many variables have factored into sea turtle nest decline that conservationists like Jean Beasley continue a valiant uphill battle. One area of concern, shrouded in uncertainty, is the effect that climate change will have on sea turtle populations.

A recent paper in PLoS ONE attempts to address this issue. While sea level rise associated with climate change will likely have a negative impact on nesting activity, these researchers focused their efforts on determining how oceanographic processes, including sea surface temperatures, would influence loggerhead nesting both in the North Pacific and Northwest Atlantic Ocean basins.

Van Houtan and Halley found that juvenile recruitment in these ocean basins was strongly correlated with marine conditions, with models of climate explaining a large percentage of observed historic changes. The historic declines in Kamouda, Japan and in Florida from 1998-2007, appear to be tied with climate variability – in particular with fluctuations that appear to on cyclical scales.

While most people are familiar with fluctuation between El Nino/La Nina climate patterns affecting weather patterns across numerous countries, more regional variability occurs in ocean basins. In the Pacific Ocean, fluctuations between “warm” and “cool” phases are termed the Pacific Decadal Oscillation, and have been demonstrated to affect salmon populations on the West Coast. In the Atlantic, the fluctuation of the Northwest Atlantic Oscillation between “positive” and “negative” phases has impacts from the smallest plankton to the largest North Atlantic Right Whale. Therefore, it should be intuitive that these basin-wide fluctuations can affect sea turtle populations.

The future of loggerheads appears to be mixed. Using predicted values from the Intergovernmental Panel on Climate Change, the researchers forecast that populations in the Pacific will be significantly reduced by 2040. Conversely, the Atlantic loggerhead populations appear to increase substantially. While this paper indicates that climate fluctuations play a major part in sea turtle populations, it doesn’t dismiss other human impacts. All people have a part to play in sea turtle conservation, so hopefully if we all work together every generation will get to experience the thrill of discovering a new nest along our beaches.