Life History Traits and Population Processes in Marine Bivalve Molluscs.
Abstract
In this dissertation, I investigated how the life history characteristics of the clam Mya arenaria determine population responses to chronic contaminant exposure. For marine bivalves, the two dominant modes of reproduction are to broadcast gametes into the water or to brood the developing embryos inside the shell. Matrix models were used to determine (from literature data on a range of species) that life span and size are the principal indicators of whether brooding or planktonic development for larvae is the reproductive strategy of a bivalve species. One consequence of the broadcast spawning strategy of M. arenaria is that juvenile recruitment to a population is uncertain. However, I showed in a stochastic matrix population model that longer life span allows populations to persist through years of low recruitment and to profit from the large, rare recruitment pulses possible with copious production of planktonic larvae. Finally, data collected on clam vital rates at contaminated and uncontaminated sites showed that recruitment history and other ecological factors, such as predation pressure, determine dynamics of populations under chronic contaminant exposure to a greater degree than do physiological impairments of adults. Contaminant effects are strongest on factors that are not particularly important to population processes in clams.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1998
- Accession Number
- ADA353542
Entities
People
- Bonnie J. Ripley
Organizations
- Massachusetts Institute of Technology