Date Awarded

1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

Romuald N. Lipcius

Committee Member

Fu-Lin E. Chu

Abstract

In estuarine crabs, there is a gradient of larval dispersal from retention within hatching habitats to export to the continental shelf. This dissertation examined the influence of physical transport and nutritional stress on recruitment success in species with different larval dispersal. In the first chapter, I examined larval vertical migration. Larvae from different families exhibited different tidally and light driven behaviors. The role of transport in selecting behaviors is associated with constraints on larval survival within the estuary. The transport of larvae was examined using a hydrodynamic model. This study compared the dispersal of vertically migrating larvae to that of non-migrating particles. Tidal migration and light limited behaviors influenced advective dispersal. Tidal shear fronts influenced larval distribution and likely effect the strength of biotic interactions. In chapter 3, I examined the impact of starvation and food quality on survival and biochemical composition of larvae with different dispersal strategies. Larvae that develop on the continental shelf generally had greater resistance to starvation than those that develop in the estuary, and they showed more efficient utilization of essential biochemical constituents during nutritional stress. Phospholipid metabolism was important in the starvation response. The biochemical composition of larvae in the field was examined to assess variability in nutritional condition over tidal time scales. Larvae in the plankton were larger and had higher contents of energetic lipids than those in laboratory studies. In the natural habitat, nutritional stress is rare and feeding conditions promote the accumulation of energetic reserves. There was a large degree of short term variability in phospholipid composition of larvae associated with small scale physical factors driving contact between zoeae and their prey. The results from this dissertation highlight the importance of small scale processes in the recruitment success of crab zoeae. While large scale gradients play an important role in selecting for dispersal, larval vertical migration behaviors reflect the influence of both small and large scale selective pressures. Tidal fronts with short durations play an important role in driving the distribution of larvae and likely influence larval feeding. Small-scale physical processes strongly influence variability in recruitment success of crab zoeae.

DOI

https://dx.doi.org/doi:10.25773/v5-fy7n-rf95

Rights

© The Author

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