Freshwater Use by Sea Snakes

University Of Florida, Gainesville FL

Investigators

Abstract

Living in seawater is challenging to marine animals such as sea snakes, which evolved from terrestrial ancestors and are widely distributed throughout much of the world's tropical ocean waters. Sea snakes were previously thought to drink seawater and excrete the excess salts using salt glands. However, recent research by the PI has shown that three species of "sea kraits" (a type of sea snake) actually dehydrate in seawater and must drink freshwater in order to remain in water balance. Marine snakes must acquire freshwater by drinking from surface lenses that form on the sea during rainfall, or from freshwater springs or estuaries along coastlines. The objectives of this research are to test whether 'true sea snakes' also require fresh water for normal water balance. These are a second lineage containing the majority of sea snake species (50+). The investigators will measure rates of dehydration in sea water and in air; observe, describe and document the drinking behaviors of sea snakes; and correlate the distribution of sea snake abundance with the local availability of fresh water. The long-range goal is to correlate the known geographic distribution of sea snakes with historic and current patterns of rainfall in both time and space, using geospatial analysis. Understanding the water requirements of sea snakes will improve the understanding of the geographical distribution of these animals, which is likely to change due to altering patterns of precipitation related to climate change. These studies may also assist in the understanding of recent population declines and local extinctions of sea snakes, which are important top predators on coral reefs. Sea snakes might be significant harbingers of climate change and could be possible indicators of the health of coral reefs, which are in serious ecological crisis. The unexpected water requirements of sea snakes might also have important implications for understanding water balance in other important marine vertebrates such as sea turtles. This project will foster international collaborations and create opportunities for training and exchange of graduate students between the United States, Costa Rica, and Australia.