32 research outputs found
Ecological distribution and niche segregation of sibling species: the case of bean beetles, Acanthoscelides obtectus Say and A. obvelatus Bridwell
Macrofauna on flood delta shoals in the Wadden Sea with an underground association between the lugwormArenicola marina and the amphipodUrothoe poseidonis
Hypoxia and sulphide as structuring factors in a macrozoobenthic community on the Baltic Sea shore: colonisation studies and tolerance experiments
Density-dependent effects of a toxicant on life-history traits and population dynamics of a capitellid polychaete
Ecophysiological differentiation of Capitella capitata (polychaeta). Sibling species from different sulfidic habitats
Effects of chronic fluoranthene exposure on sibling species of Capitella with different development modes
Joint effects of a toxicant and population density on population dynamics:an experimental study using Capitella sp. I (Polychaeta)
Effects of fluoranthene and ambient oxygen levels on survival and metabolism in three sibling species of Capitella (Polychaeta)
Variability in reproductive mode and larval development within the Capitella capitata species complex
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Joint effects of population density and toxicant exposure on population dynamics of Capitella sp I
Very few studies have analyzed the dependence of population growth rate on population density, and even fewer have considered interaction effects of density and other stresses, such as exposure to toxic chemicals. Yet without such studies we cannot know whether chemicals harmful at low density have effects on carrying capacity or, conversely, whether chemicals reducing carrying capacity are also harmful at low density, impeding a population's capacity to recover from disturbance. This study examines the combined effects of population density and a toxicant (fluoranthene) on population growth rate (pgr) and carrying capacity using the deposit-feeding polychaete Capitella sp. I as a test organism. Populations were initiated with a stable age distribution, and population density and age/size distribution were followed during a period of 28 wk. Fluoranthene (FLU), population density, and their interaction influenced population growth rate. Population growth rate declined linearly with the logarithm of population biomass, but the slope of the relationship was steeper for the control populations than for populations exposed to 50 mug FLU/(g sediment dry mass). Populations exposed to 150 mug FLU/(g sediment dry mass) went extinct after 8 wk of exposure. Despite concerns that toxicant effects would be exacerbated at high density, we found the reverse to be the case, and effects of fluoranthene on population growth rate were much reduced in the region of carrying capacity. Fluoranthene did. reduce carrying capacity by 46%, and this could haven important implications for interacting species and/or sediment biogeochemical processes