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We investigated variations in the small-to meso-scale abundance and distribution of the 6 most abundant seabird species in the northern California Current -black-footed albatross Phoebastria nigripes, sooty shearwater Puffinus griseus, pink-footed shearwater Puffinus creatopus, forktailed storm-petrel Oceanodroma furcata, common murre Uria aalge, and Cassin's auklet Ptychoramphus aleuticus -during the upwelling season of 2000 and 2002. Covariates (21 total), with importance assessed using logistic and generalized linear modeling and an information theoretic approach, included physical features such as sea surface temperature, dynamic height (apparent water-column pressure), and pycnocline depth; biological factors such as chlorophyll maximum; and food-web factors such as the density of 3 size classes of zooplankton, the density of potential piscine competitors, i.e. Pacific salmon Oncorhynchus spp., and abundance of fish prey such as zooplankton, northern anchovy Engraulis mordax, and the juveniles of salmon and demersal fishes. The most important factors explaining seabird occurrence changed from mesoscale physical features during a food-rich year (2002; exhibited over 15 to 30 km) to smaller-scale occurrence of actual prey patches during a food-poor year (2000; <1 km). Spatial overlap in occurrence of murres and shearwaters with adult salmon was interpreted as co-occurrence and, perhaps, competition for prey species; a negative spatial overlap between shearwaters and abundance of forage fish was interpreted as evidence for prey depletion (or predator-induced alteration of availability) by the birds and other co-occurring predators (salmon). Overall, results and other information indicated the value of adding spatially explicit data on predator and prey species abundance and predator-prey behavior to improve foodweb modeling.

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Reese, D. C., O'Malley, R. T., Brodeur, R. D., and Churnside, J. H. 2011. Epipelagic fish distributions in relation to thermal fronts in a coastal upwelling system using high-resolution remote-sensing techniques. – ICES Journal of Marine Science, 68: 1865–1874. Coastal upwelling systems are characterized by substantial spatial and temporal variability with respect to surface conditions, with fauna patchily distributed and high abundances in localized areas. Examining habitat associations on finer spatial scales than previous studies have been able to achieve would advance the understanding of important marine coastal ecosystems. This study evaluates the spatial and temporal relationships of single fish and fish schools with sea surface temperature (SST) fronts in the northern California Current upwelling system, using lidar (light detection and ranging) from an aircraft to sample surface waters over the continental shelf. High-resolution data were collected on the distribution of surface nekton and SST, then the locations of fish were analysed with respect to their proximity to SST fronts using GIS spatial analyses. Both fish schools and solitary fish were located significantly closer to fronts than would be expected by chance. The association of fish to fronts varied with the progression of the upwelling season such that fish associated less with fronts under stronger upwelling conditions. The relationships observed indicate the importance of thermal features to fish as a habitat component in a variable upwelling environment and have implications for management and conservation.