SS1.05 How Will Aquatic Ecosystems Respond to Climate Change?
Date: Tuesday, June 11, 2002
Location: Oak Bay
 
ZeidbergL, UCLA, Los Angeles, USA, zeidberg@ucla.edu
 
DISTRIBUTION OF SQUID PARALARVAE, LOLIGO OPALESCENS (CEPHALOPODA: MYOPSIDA), IN THE SOUTHERN CALIFORNIA BIGHT IN THE THREE YEARS FOLLOWING THE 1997 EL NINO
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Large numbers of paralarvae of the California market squid, Loligo opalescens (10,560 paralarvae from 422 plankton samples) were collected in the Southern California bight in 1999, 2000, and 2001 during the spawning season. Paralarvae abundance increased dramatically (p<0.0041) from 1.5 squid/1000m3 in 1999 to 77.9 squid/1000m3 in 2000 and 73.6 squid/1000m3 in 2001 following the El Niņo of 1998. The effects on the squid fishery of the 1997-1998 El Nino thus were extended for two years, with larval abundance reduced until the 1999-2000 spawning season. Paralarvae were abundant close to shore for up to a month after hatching in 2000 (p<0.003), with tidal surface currents adjacent to shore in the Channel Islands dramatically affecting paralarvae abundance. Tidally reversing currents within 1-3 kilometers of shore create a boundary layer of 'sticky water' within which paralarvae remain entrained inshore immediately after hatching. Neritic currents further from shore disperse older paralarvae within the Southern California bight. The greatest change in paralarval abundance, for all transects, was observed within one kilometer of the transition between these two flow regimes. Age of paralarvae (from statolith increments) entrained within the Catalina Island boundary layer averaged 13 days and 16 days, but some individuals remained nearshore for up to a month. Paralarvae within the boundary layer occur above 80 meters both day and night and they exhibit a statistically significant pattern of vertical diel migration (p<0.01). Paralarvae at sea were disproportionately abundant adjacent to fronts associated with upwelling events.