Effects of Climate Variability on InterannualVariation in Parasites, Pathologies,and Physiological Attributes of Bivalvesfrom the U.S. East, Gulf, and West Coasts

摘要

We analyzed weighted prevalence of various parasites and pathologies for 1995 to2006 along with a set of physiological variables to determine the degree of concor-dancy in their interannual variations over 500-km stretches of coastline using datafrom the National Oceanic and Atmospheric Administration's (NOAA's) NationalStatus and Trends "Mussel Watch" Program. The variables examined in mytilidmussels fell into three groups based on the temporal patterns observed: ceroid bodies,taxon richness, digestive tubule atrophy, and major pathologies varied concordantlyalong the Northeast and West Coasts. For reproductive stage, sex ratio, and gill ciliates,concordant temporal trends were limited to the northeast coast. Gregarines, found only inWest coast mussels, behaved similarly to those variables falling into the first group. Afinal group, trematode metacercariae and sporocysts, tissue pathologies, and the prokary-otes, was characterized by limited concordancy. For oysters, a similar triplet of groupswas identified. Digestive tubule atrophy, tissue pathology, ceroid bodies, and body/mantlegregarines showed concordant temporal trends on both the East and Gulf Coasts. ForDermo disease, gill gregarines, reproductive stage and nematodes, temporal concordancyin interannual variation was limited to the Gulf coast. Little concordancy was observedfor the prokaryotes, gill and digestive tract ciliates, haplosporidians, cestodes, sex ratio,and taxon richness. Overall, principal pathologies and diseases, bivalve physiologicalindicators, and the common gregarine parasites tended to show concordant behavior,suggesting that large-scale climatic processes [e.g., the El Nino/Southern Oscillation(ENSO) and the North Atlantic Oscillation (NAO)] are important determinants of theirinterannual variation. Overall, multicellular parasites, prokaryotes, and ciliates rarelyshowed concordant behavior, indicating that parasite body burden was controlled bylocal (within-bay) forcing factors. Mussels and oysters exhibited amazing similarity intheir responses to local and climatic forcing. For both taxa, concordant behavior wasobserved for the most commonly observed pathologies, ceroid bodies, digestive tubuleatrophy, reproductive stage, and the most abundant single-celled parasites such as thegregarines. These variables encompass the majority of the biological non-parasite vari-ables measured and the majority of the common parasites. For both taxa, concordantbehavior was rarely observed for the multi-cellular parasites. Both bivalve groups con-tained variables that expressed concordant behavior not only over long stretches of coast-line, but on multiple coasts and variables that expressed concordant behavior for morelimited coastline stretches. The degree and pattern of concordancy are fingerprints for therelative influence of local versus climatic forcing as the determinants of populationdynamics in these bivalves populations and the populations of their parasites.