Abstract
Author(s): Baumsteiger, Jason; Schroeter, Robert E.; O'Rear, Teejay; Cook, Jonathan D.; Moyle, Peter B. | Abstract: The overbite clam (Potamocorbula amurensis) is a major invasive species in the San Francisco Estuary, California, and has been implicated in the decline of pelagic productivity and native fish species. Little is known of its impact on Suisun Marsh, a large brackish tidal region of the estuary. We looked at the abundance and spatial distribution of clams in the marsh, including examining the influence of water quality, using long-term (1988–2015) otter trawl surveys. Temporal trends indicated that overbite clam abundance has been increasing, but adult clams were spatially restricted to a single large slough (Suisun). Clams were absent from most interior channels, limiting their overall effect on the marsh aquatic ecosystem. Abiotic variables, particularly salinity, proved important predictors of overbite clam abundance, although the variables examined alone could not explain overbite clam distributions. We propose that connectivity, detritus loads, and/or predation pressure may work in conjunction with abiotic variables to cause poor survival rates for recruits in interior marsh sites, keeping the distribution limited. Overall results are encouraging for restoration projects in brackish tidal marshes that need to deal with overbite clams.
Highlights
Non-native bivalves have been introduced into many estuaries, with significant consequences to aquatic communities (Sousa et al 2009)
Over 92% of all overbite clams captured in Suisun Marsh were taken from two sites (SU3 and SU4) in lower Suisun Slough (Figures 1 and 2B)
Given overbite clam’s high filtration rates (Greene et al 2011), their high abundance in lower Suisun Slough could reduce the supply of phytoplankton and zooplankton transported up the slough from Grizzly Bay to smaller, more interior sloughs
Summary
Non-native bivalves have been introduced into many estuaries, with significant consequences to aquatic communities (Sousa et al 2009). Many of these species are extremely prolific, are adaptable, and are highly efficient predators on plankton (Alpine and Cloern 1992; Dame 1996; Pace et al 1998; Strayer et al 1999). Prevention and control of bivalve invasions has become a priority in estuarine management One such system experiencing altered food-web dynamics and serious depletions in phytoplankton is the San Francisco Estuary (the estuary) (Nichols et al 1990; Greene et al 2011).
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