Spatial variability of larval fish in relation to their prey and predators fields: interactions from cm to 10s of km in a subtropical, pelagic environment

Dr. Robert Cowen, Hatfield Marine Science Center at Oregon State University (Lead PI)

Dr. Su Sponaugle, Hatfield Marine Science Center at Oregon State University, (Co-PI)

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The spatial pattern of organisms within pelagic marine environments has long been recognized to be of significant ecological importance, and this is particularly true for larval fishes. The degree to which larvae can survive their time in the plankton depends on successful feeding and avoidance of predation, yet we know little of these interactions on the scales of relevance to the larval fish. Patchy prey and predator environments should lead to variation in predator-prey interactions, which underlie variation in larval fish growth and survival. Yet, dissecting the components of these overall outcomes is complex, due in large part to the broad range of spatial scales involved, and technological challenges with adequately sampling the various processes simultaneously. Our current NSF-sponsored study uses new technology (In Situ Ichthyoplankton Imaging System – ISIIS, now re-named, DPI) to simultaneously measure the in situ, fine-scale distribution of larval fishes, in relation to their prey and their planktonic predators. A novel combination of detailed in situ sampling of the horizontal and vertical distributions of plankton, targeted fine-scale net sampling, and analyses of individual-level recent daily larval growth is enabling the identification of the biological and physical processes driving fine-scale plankton distributions. The overall goal is to quantify the patterns and consequences of the fine-scale to sub-mesoscale distributions of larval fishes, their prey, and their predators near and across a major western boundary current passing through the Straits of Florida. By sampling a series of water masses at very high resolution, the study will address specific hypotheses concerning: i) the drivers of aggregations and patchiness, and ii) the biological consequences of predator-prey interactions at fine scales.

Funding provided by the National Science Foundation