Thomas L. Forbes

EFFECTS OF 4-n-NONYLPHENOL ON LIFE-HISTORY TRAITS AND POPULATION DYNAMICS OF A POLYCHAETE

A Life-Table-Response Experiment lasting 78 d was performed to investigate the toxic effects of sediment-associated 4-n-nonylphenol (NP) on growth, reproduction, and survivorship of isolated hermaphrodites of the infaunal polychaete Capitella sp. I. Demographic effects were evaluated using both a fully age-classified and a simple two-stage model to estimate population growth rates (λ). Decomposition analysis was performed to explore the contributions of each of the affected life-history traits to the effects observed on λ. Elasticity analysis was applied to examine the relative sensitivity of λ to changes in each of the different life-history traits under different exposure levels. In the lowest NP treatment (14 μg NP/g dry mass of sediment) significant stimulatory effects were observed for both asymptotic body volume and average brood size, but these did not result in a significant effect on λ. Negative effects on brood size, volume-specific fecundity, time to first reproduction, and individual growth ra...

Individual physiological responses to environmental hypoxia and organic enrichment: implications for early soft-bottom community succession

Infaunal inhabitants of coastal marine sediments occupy environments along a continuum from extremely food-rich, low-oxygen regions to food-poor habitats with relatively high levels of available oxygen. In organic-rich sediments, efficient utilization of available organic matter by deposit-feeding macrofauna may often be limited by the supply of oxygen. Specific feeding rate, growth, and production efficiency were measured on single individuals of the polychaete Capitella species 1 to determine whether previously measured declines in growth rates in response to hypoxia were due to decreased feeding, decreased conversion efficiency, or both. Under otherwise constant conditions, feeding rate was determined by the nitrogen content of the sediment, with a greater nitrogen content generally leading to higher specific feeding rates in a manner consistent with recent interpretations of optimal foraging theory

Linking structure and function in marine sedimentary and terrestrial soil ecosystems: implications for extrapolation from the laboratory to the field

A central goal of ecotoxicology is the development of sufficient ecological understanding to enable the accurate prediction of the behaviour and effects of contaminants in the environment. Progress toward this goal has been slow. We believe future advancement requires increased emphasis on interdisciplinary studies which comprehensively investigate chemical fate and effect at spatial and temporal scales relevant to the natural systems of interest (Forbes and Forbes, 1994). Building a bridge from the laboratory to the field will require improved extrapolation models incorporating a more complete understanding of the relationship between ecosystem structure and function than presently exists (Forbes and Forbes, 1993)