unaware of any study that has examined the in?uence of thin layers on the behavior of individual gelatinous Spatial and temporal heterogeneity affect movement zooplankton. and resource use by animals (Levin et al. , 2000). In Gelatinous zooplankton, including ctenophores, particular, behaviors that allow organisms to locate medusae, and siphonophores, tend to aggregate at and exploit patches of food represent key in?uences density, salinity, and temperature discontinuities that on trophodynamics. For plankton, external forcing develop in coastal transition zones, estuaries, and (e. g. , currents, shear, and turbulence) combines with fjords (Owen, 1989; Graham et al. , 2001). Aggre- behavioral responses to determine the structure and tions of gelatinous species can arise if discontinuities function of assemblages, access to food, and the ?ow act as a physical or physiological barrier or if of carbon across a range of spatial and temporal detectable boundary conditions stimulate appropriate scales (e. g. , Bochdansky & Bollens, 2004). behavioral responses. For example, ?eld surveys At a micro-scale, thin layers represent persistent, showed that Sarsia tubulosa (M. Sars, 1835) agg- spatially coherent patches of plankton (Donaghay gated at a discontinuity (Hansen, 1951), and in the et al. , 1992; Cowles et al. , 1998).
