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Effects of seston variability on the clearance rate and absorption efficiency of the mussels Aulacomya maoriana, Mytilus galloprovincialis and Perna canaliculus from New Zealand

2002; Elsevier BV; Volume: 268; Issue: 1 Linguagem: Inglês

10.1016/s0022-0981(01)00378-1

1879-1697

Jonathan P. A. Gardner,

Environmental Toxicology and Ecotoxicology

The clearance rates (CR in l g−1 h−1) and net absorption efficiencies (AE) of three co-occurring mytilid species were estimated to determine the effects of variation in ambient seston quantity (total particulate matter, TPM, mg l−1) and quality (particulate organic matter, POM, mg l−1; percent organic matter, PCOM=POM/TPM) on these physiological functions. CRS estimates were significantly different among the species (Mytilus galloprovincialis>Perna canaliculus=Aulacomya maoriana), but were not correlated with differences in species-dependent mean body size (P. canaliculus>M. galloprovincialis>A. maoriana). AE estimates were independent of mean body weight, and did not differ among the species. For all three species, CR responded in a simple linear manner to seston organic content, either in terms of POM (for A. maoriana and M. galloprovincialis), or PCOM (for P. canaliculus). The AE response, although also of a simple linear type, was species-dependent and involved interactions of two or three seston components: TPM, POM and PCOM for A. maoriana; POM and PCOM for M. galloprovincialis; and TPM and PCOM for P. canaliculus. For all three species, seston variation explained 15–20% of the variation in CR and 52–59% of the variation in AE. Comparisons among the species indicated that two very different responses to variation in seston quantity and quality exist. First, significant differences in CR result from species-dependent differences in the magnitude of the response to seston variation. Second, species-dependent responses to variation in seston variation resulted in the similarity of the AE responses. Thus, the three species appear to have evolved different strategies for dealing with seston variation, but with the end result that their AE responses do not differ. Finally, no evidence was found of a negative association between CR and AE for any of the three species, suggesting that under the seston conditions experienced in this work, these species do not have the physiological compensatory capacity to reduce CR in order to increase AE. The importance of a comparative (i.e., multi-species) approach utilising ambient seston is emphasised by the findings of this research if we are to understand better the feeding and digestive physiologies of suspension-feeding organisms such as mussels.