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SPATIAL DISTRIBUTIONS OF BURROWING SHRIMP POPULATIONS IN TWO OREGON ESTUARIES
Citation:
DeWitt, T H. AND P M. Eldridge. SPATIAL DISTRIBUTIONS OF BURROWING SHRIMP POPULATIONS IN TWO OREGON ESTUARIES. Presented at Estuarine Research Federation, Seattle, WA, September 14-18, 2003.
Description:
Thalassinid burrowing shrimp (Neotrypaea californiensis and Upogebia pugettensis) inhabit large expanses of Pacific estuarine tide flats, from British Columbia to Baja California. The spatial distribution of shrimp populations within estuaries has rarely been quantified because of difficulty of quantitatively sampling organisms that burrow to 100 cm underground. To understand how thalassinids affect estuarine-scale processes, we developed methods to rapidly estimate shrimp identity and abundance (using burrow opening architecture and density) and mapped populations of both species within the Yaquina River and Salmon River (OR) estuaries. Burrowing shrimp occupied >80% of the euryhaline and mesohaline intertidal flats in both estuaries, and covered >600 ha of tideflats over a distance of 17 km upriver in the Yaquina estuary. Aerial coverage for both species was similar within the Yaquina, although Upogebia dominated tideflats in the lower estuary and Neotrypaea dominated upriver. In much of the lower Yaquina, Upogebia occupied the mid- to lower intertidal zone and Neotrypaea the upper intertidal, but where Upogebia was absent, Neotrypaea populations extended down to the lower intertidal. In the Salmon estuary, Neotrypaea dominated >95% of the tideflats and populations extended throughout the intertidal and into the subtidal zone. Physiological tolerances and competition may cause these spatial patterns.