Effect of yolk utilization on the specific gravity of chokka squid (Loligo reynaudii) paralarvae: implications for dispersal on the Agulhas Bank, South Africa
Authored by Coleen L Moloney, Rodrigo S Martins, Michael J Roberts, Nicolette Chang, Erica A G Vidal, Philippe Verley
Date Published: 2010
DOI: 10.1093/icesjms/fsq098
Sponsors:
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Platforms:
Ichthyop
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
Specific gravity is an important parameter in the dispersal of marine
zooplankton, because the velocity of currents, and therefore the speed
of transport, is usually greatest near the surface. For the South
African chokka squid (Loligo reynaudii), recruitment is thought to be
influenced by the successful transport of paralarvae from the spawning
grounds to a food-rich feature known as the cold ridge some 100-200 km
away. The role of paralarval specific gravity on such transport is
investigated. Specific gravity ranged from 1.0373 to 1.0734 g cm(-3)
during the yolk-utilization phase, implying that paralarvae are always
negatively buoyant, regardless of yolk content. The data were
incorporated into a coupled individual-based model (IBM)-Regional Ocean
Modelling System model. The output showed that dispersal was dominantly
westward towards the cold ridge. Also, modelled paralarval vertical
distribution suggested that hydrodynamic turbulence was an important
factor in dispersal. The negative buoyancy of early chokka squid
paralarvae may reduce the risk of paralarvae being advected off the
eastern Agulhas Bank and into the open ocean, where food is less
abundant, so specific gravity may be important in enhancing the survival
and recruitment of chokka squid.
Tags
Model
Temperature
Life-history
Vertical-distribution
Vulgaris-reynaudii
Spawning grounds
Larval fish
Buoyancy
Eggs
Hatchling
squid