Publication Date:
2021-06-25
Description:
The coastal Pacific Ocean off northern and central California encompasses the strongest seasonal upwelling zone in the California Current ecosystem. Headlands and bayshere generate complex circulation features and confer unusual oceanographic complexity. We sampled the coastal epipelagic fish community of this region with a surface trawl in the summer and fall of 2000–05 to assess patterns of spatial and temporal community structure. Fifty-three species of fish were captured in 218 hauls at 34 fixed stations, with clupeiform species dominating. To examine spatial patterns, samples were grouped by location relative to a prominent headland at Point Reyes and the resultingtwo regions, north coast and Gulf of the Farallones, were plotted by using nonmetric multidimensional scaling.Seasonal and interannual patterns were also examined, and representative species were identified for each distinct community. Seven oceanographic variables measured concurrently with trawling were plotted by principal components analysis and tested for correlation with bioticpatterns. We found significant differences in community structure by region, year, and season, but no interaction among main effects. Significant differences in oceanographicconditions mirrored the biotic patterns, and a match between biotic and hydrographic structure was detected.Dissimilarity between assemblages was mostly the result of differences in abundance and frequency of occurrence of about twelve common species. Community patterns were bestdescribed by a subset of hydrographic variables, including water depth, distance from shore, and any one of several correlated variables associated with upwelling intensity. Rather than discrete communities with clear borders and distinct member species, we found gradients in communitystructure and identified stations with similar fish communities by region and by proximity to features such asthe San Francisco Bay.
Keywords:
Biology
;
Ecology
;
Fisheries
Repository Name:
AquaDocs
Type:
article
,
TRUE
Format:
application/pdf
Format:
application/pdf
Format:
261-281
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