Behavioral Ecology of Mobile Animals: Insights from In Situ Observations

Abstract

We draw on three primary examples from our collective work on mobile decapod crustaceans, fish, and humans, as well as the work by others on fish and invertebrates, to illustrate the beneficial influence of in situ observations on behavioral ecology, marine conservation, and education. Diver observations of mass migration and gregarious behavior in Caribbean spiny lobster (Panulirus argus) in the 1960s led to over 40 years of experimentation that identified (1) the environmental factors driving the mass migration of lobsters each fall, (2) queues of migrating lobsters that afforded them the benefits of reduced hydrodynamic drag and predation, (3) the body-odor attractant underlying gregarious behavior, and (4) the use of gregariousness as a type of “guidepost effect” that minimizes search time for shelter. In situ observation of spider crabs in kelp forests off central California showed complex resource partitioning along multiple niche dimensions in a guild of five species, driven by intense predation pressure by an array of fish and sea otters. Ultrasonic telemetry and innovative tagging studies, as well as diver-deployed experiments, revealed blue crab movement and behavior in murky estuarine waters of the Chesapeake Bay where direct visual observation is impossible. Over three decades, these studies showed mechanisms of dispersal and migration, foraging behavior in response to patchily distributed prey, and habitat selection for molting and minimization of intense cannibalism of juveniles by adults. We also highlight how in situ observations helped to refine behavioral ecological theory by testing whether humans display a relatively simple or sophisticated predatory response to varying densities of spiny lobster prey. Knowledge of human predatory behavior can identify how effective certain fishery management policies will be in sustaining the spiny lobster fishery. Improved conservation is also afforded by the knowledge about the novel responses of these mobile organisms to both the fishery disturbance and the nondisturbed habitats via lobster spill-in to marine protected areas (MPAs). The results also have value in improved diver education relating to reducing injury to sublegal lobsters. In situ observations have also contributed to our knowledge of differential reproductive strategies, species invasions, and range extensions, as well as novel behaviors. While no single research tool is or will be capable of addressing the entirety of these behavioral scales, it is clear that in situ observations have made, are making, and will continue to make profound contributions to the field of behavioral ecology