Ecology and Evolution of Marine Life Histories

Evolution of early life histories-

The impacts of predation, advection and ultraviolet radiation on early life histories of crabs are being studied throughout this hemisphere. We previously have shown that predation by planktivorous fishes may be the primary evolutionary force explaining the diversity of reproductive timing and larval migration patterns of coastal crabs, and I was invited to review reproductive timing patterns in rocky shore communities.

This summer three types of studies were conducted in my laboratory to determine whether my paradigm applies to crabs living in dynamic upwelling zones, where physical forcing could play a larger role than predation. We determined the 1) hatching rhythms of the common intertidal crabs relative to tidal, tidal amplitude, lunar and light-dark cycles, 2) the ability of predatory fishes to delay the timing of larval release and 3) the abundance and feeding preferences of predatory fishes relative to the four environmental cycles.Crabs released larvae when they were rapidly swept away from high densities of fishes under the cover of darkness, as they do elsewhere in the world, and they did not delay larval release in the presence of predatory fishes.

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