Remarkable invasion of San Francisco Bay (California, USA), by the Asian clam Potamocorbula amurensis. II, Displacement of a former community

Abstract

Long-term macrobenthic sampling at a site in northern San Francisco Bay has provided an unusual opportunity for documenting the time course of an invasion by a recently introduced Asian clam Potamocorbula arnurensis. Between 1977, when sampling began, and 1986, when the new clam was first discovered, the benthic commun~ty varied predictably in response to river inflow. During years of normal or high river inflow, the community consisted of a few brackish or freshwater species. During prolonged periods of low river inflow, the number of species doubled as estuarine species (e.g. Mya arenana) migrated up the estuary. In June 1987, at the beginning of the longest dry period in recent decades, large numbers (> 12 000 m-') of juvenile P. arnurensis were discovered at the site. By midsummer 1988 the new clam predom~nated (> 95 %) in both total number of individuals and biomass, and the expected dry-penod estuarine species did not become re-established. The rapid rise of P. arnurensls to numerical dominance throughout the region of the original introduction was probably facilitated by the fact that this region of the bay had been rendered nearly depauperate by a major flood in early 1986. Once introduced, the clam had sufficient time (> 1 yr) to become well established before the salinity regime was appropriate for the return of the estuarine species. Subsequently, the new clam was apparently able to prevent the return of the dry-period community. Its ability to live in low salinity water (< 1 %o) suggests that P. amurensis may not be displaced with the return of normal winter river flow and, therefore, may have permanently changed benthic community dynamics in this region of San Francisco Bay.

Biology and interspecific interactions of the alien crabPercnon gibbesiin the Maltese Islands

“…Competition in particular is increasingly recognized as a major means through which non-indigenous species have an impact on native species (Nichols et al 1990;Byers 2000). From this study and that by Muller (2001), it appears that P. gibbesi and P. marmoratus are potential competitors for space Á and according to Muller (2001), also for food Á since the two species have been observed to occur in close proximity.…”

Effects of nutritional deprivation on juvenile green sturgeon growth and thermal tolerance

“…The recent colonization and domination of the SFE benthos by Corbula amurensis Schrenck, 1861 (the Asian overbite clam) (Feyrer et al 2003;Cloern and Jassby 2012) has displaced many of these prey species (Nichols et al 1990;Gilbert et al 2011;Greene et al 2011;Cloern and Jassby 2012). Other sturgeon species have been shown to successfully adjust their diet to altered prey availability (Brosse et al 2000;Usvyatsov et al 2012), and the Asian overbite clam has been identified as a major component of the diet of the sympatric white sturgeon (Kogut 2008).…”

Impacts of two introduced suspension feeders in Port Phillip Bay, Australia

“…The catastrophic ecological impacts of introduced species such as the Asian clam Potamocorbula amurensis in San Francisco Bay (Nichols et al 1990) and the comb jelly Mnemiopsis leidyi in the Black Sea (Shushkina & Musayeva 1990) have highlighted the significance of introduced species in the marine environment (including bays, estuaries, and open coasts). Although there has been a rapid increase in the study of the ecological consequences of marine invasions in the past decade (e.g.…”