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Michelle Lloyd

Patterns in the larval vertical distribution of marine benthic invertebrates in a shallow coastal embayment

Michelle Lloyd
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I studied animal biology at Thompson Rivers University and Bamfield Marine Science Centre. After completing my BSc at Thompson Rivers University in 2005, I monitored commercial fisheries as an at-sea fisheries observer, taught marine and coastal ecology as a marine science educator, and maintained Northern abalone stocks and an abalone hatchery as a biologist and manager. In 2008, I moved from the west to the east coast of Canada to study biological oceanography at Dalhousie University. As a marine scientists and educator, I am interested in the conversation and sustainable development of marine environments.

Anna Metaxas

Oceanography, Dalhousie University

09/2008 - 09/2011

Population Connectivity, PC-06: Population connectivity and dispersal in contrasting species

michelle.lloyd@dal.ca

Processes during the meroplanktonic phase regulate population dynamics for many marine benthic invertebrates. I examined changes in vertical distribution of different meroplanktonic larvae in a coastal embayment during a stable period, at high temporal frequencies and spatial resolutions. Plankton samples were collected at 6 depths (3, 6, 9, 12, 18, 24 m) using a pump, every 2-h over a 36- and a 25-h period, during a spring and neap tide, respectively, concurrently with measures of temperature, salinity, fluorescence and current velocity.

For 10 gastropod taxa (Margarites spp., Crepidula spp., Astyris lunata, Diaphana minuta, Littorinimorpha, Arrhoges occidentalis, Ilyanassa spp., Bittiolum alternatum and Nudibranchia), larval vertical distribution was mostly related to the thermal structure of the water column.  The key factors determining the vertical distribution of gastropod larvae were temperature, fluorescence, and light, although the importance of each factor varied among taxa. Differences in vertical distribution may enable these larvae to partition over a wide range of potential habitats for settlement.

Each of 7 larval taxonomic groups was found either exclusively near the surface (asteroids), below the thermocline (bivalves, gastropods and polychaetes), associated with the fluorescence maximum (bryozoans and shrimp), or showed diel changes in distribution (crabs, shrimp, gastropods and polychaetes). These larvae that occupy different depths in the water column exhibit different dispersal potentials.

 

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