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Marine Ecology Progress Series

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MEPS 503:139-156 (2014)  -  DOI:

Bay-scale patterns in the distribution, aggregation and spatial variability of larvae of benthic invertebrates

Rémi M. Daigle1,*, Anna Metaxas1, Brad deYoung2

1Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
2Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland A1B 3X9, Canada
*Corresponding author:

ABSTRACT: This study aimed to investigate mechanisms of pattern formation in the larval distributions of benthic invertebrates by relating the spatial and temporal variability in the larval distributions to that of physical and biological variables, such as temperature, salinity, fluorescence and current velocity. Larvae were sampled at 11 sites on Aug 7-8 and 11-12, 2008 and at 16 sites on Aug 2-4, 2009, with a 200 µm plankton ring net (0.75 m diameter) towed for 5 min at 3 m and 12 m depth (in and below the mixed layer, respectively) in St. George’s Bay, Nova Scotia, Canada. In 2009, density, temperature, salinity, and fluorescence were measured with a conductivity-temperature-density (CTD) cast at each station, and currents were quantified with an acoustic Doppler current profiler (ADCP) moored at 5 locations throughout the bay. In 2008, we only measured temperature. Gastropod, bivalve and, to a lesser extent, bryozoan larvae had very similar spatial distributions, but the distribution of decapod larvae followed a different pattern. These findings suggest that taxonomic groups that have functionally (i.e. swimming ability) similar larvae (e.g. bivalves and gastropods) also show similar dispersion properties (distribution and spatial variability), while the opposite is true for groups with functionally dissimilar larvae (e.g. bivalves and decapods). We also found that larval distributions of all taxa were significantly aggregated, although the degree of aggregation varied among taxa. Using an aggregation-diffusion model, we demonstrated that horizontal swimming was not an effective means of forming aggregations even at modest levels of diffusion. We hypothesize that patterns in observed horizontal distribution at this scale (<40 km) are determined during the larval phase, and that the primary mechanism for pattern formation is larval interaction with physical oceanographic structures (e.g. stratification and tidal currents).

KEY WORDS: Larval distribution · Larval aggregation · Aggregation-diffusion model · Larval dispersal · Larval ecology · Long residence times

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Cite this article as: Daigle RM, Metaxas A, deYoung B (2014) Bay-scale patterns in the distribution, aggregation and spatial variability of larvae of benthic invertebrates. Mar Ecol Prog Ser 503:139-156.

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