TY - JOUR
T1 - Joint effects of population density and toxicant exposure on population dynamics of Capitella sp. I
AU - Forbes, Valery E.
AU - Sibly, Richard M.
AU - Linke-Gamenick, Inez
PY - 2003/8
Y1 - 2003/8
N2 - 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 μg FLU/(g sediment dry mass). Populations exposed to 150 μg 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 have important implications for interacting species and/or sediment biogeochemical processes.
AB - 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 μg FLU/(g sediment dry mass). Populations exposed to 150 μg 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 have important implications for interacting species and/or sediment biogeochemical processes.
KW - Capitella sp. I
KW - Carrying capacity
KW - Ecotoxicology
KW - Fluoranthene
KW - Life table response experiment
KW - Population growth rate
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U2 - 10.1890/1051-0761(2003)13[1094:JEOPDA]2.0.CO;2
DO - 10.1890/1051-0761(2003)13[1094:JEOPDA]2.0.CO;2
M3 - Article
AN - SCOPUS:0347530297
SN - 1051-0761
VL - 13
SP - 1094
EP - 1103
JO - Ecological Applications
JF - Ecological Applications
IS - 4
ER -