Molluscan Colonization of Different Sediments on Submerged Platforms in the Western Baltic Sea+)

108

Infaunal successional patterns in Alewife Cove, a small estuary in southeastern Connecticut, USA, varied significantly seasonally and along the estuarine environmental gradient. Each study site exhibited different patterns of change in species composition and abundance. However, suites of species found during success~on did not differ greatly from those found in ambient sediments. Species w h~c h exhibited the most variable population changes during succession were numerically dominant tubiculous polychaetes (Streblospro benedicti, Capitella spp., Polydora ljgni], and an oligochaete (Peloscolex gabriellae). Other species which exhibited significant activity were the polychaetes Scoloplos fragilis, Hobsonia florida and Nereis virens, the hemichordate Saccoglossus kowaleski, and the amphipods Microdeutopus gryllotalpa and Corophium insidiosum. At certain times, densities of these species exceeded or were equivalent to dominant species densities in ambient sediments and experimental plots. Timing of disturbance greatly influenced succession Succession after a n early spring disturbance was characterized by peak species dens~ties and numbers. Succession following a fall disturbance was abbreviated with few species at low densities, while after a summer disturbance intermediate trends were found. Classification analysis of similarity between ambient and successional community structure indicated that recovery to ambient conditions occurred rapidly in the lower reach (14 to 30 d ) , while successional changes in the middle and upper basins continued at least until the end of the winter. It is apparent that estuarine succession can be quite varidble and that re-establishment of community structure may occur over various time scales w~t h no set sera1 stages. The physical and biological processes appearing to b e important determinants of estuarine succession include (1) timing of disturbance, (2) habitat in w h~c h the disturbance takes place, (3) reproductive periodicity of infauna, (4) ambient population dynamics which generate the pool of recolonizers, ( 5 ) abiotic and biotic factors (e.g. food and space resources that affect the preceding 4 factors).

Section: Discussioncontrasting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Responses of Estuarine Infauna to Disturbance. II. Spatial and Temporal Variation of Succession

Zajac¹,

Whitlatch²

1982

108

“…Species-specific settlement preferences, either for different sediment types, for different depths or other unknown but correlated factors, are an obvious potential mechanism causing the observed distributions (Gray 1974). Experimental sediment transplants, such as that camed out by Richter & Sarnthein (1977) in the Wadden Sea, may be the only way to separate these factors, in terms of their relative importance.…”

Section: Discussionmentioning

confidence: 99%

“…water movement, oxygen supply, nutrients) (Richter & Sarnthein 1977, Johnstone et al 1988). These in turn may affect a range of biological factors, such as the accumulation of detritus, productivity and microbial activity; physical factors may mediate disturbance or predator effects, whether by epibenthic organisms (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spatial pattern in the abundance and structure of mollusc populations in the soft sediments of a coral reef lagoon

Jones¹,

Ferrell²,

Sale³

1990

ABSTRACT. A hierarchical sampling programme, carried out during October 1985, encompassed 4 spatial scales: broad habitat zones of different depth and sebment composition; random 1 ha locations within zones; random 25 m2 sites within locations; and random 0.01 m2 air-lifted cores from each site. Of 69 species collected, we describe the patterns of distribution of the 10 most common. Spatial differences in their abundances were observed at all scales, but most of the variation (50 to 85 %) occurred at the broadest scale -between zones. Zones of peak abundance differed among species, some being most abundant in deep, fine-sediment habitats, e.g. Tellina cf. myaformis; some in deep, intermediatesediment habitats, e.g. Exotica cf. virgulata and Pupa nitidula; others in shallow, coarse-sediments to the north, e.g. Tellina obtusalis, Umbonium guamensis; and still others in the shallow sediments to the south, e.g. Rhinoclavis aspera. In terms of population structure, tellinid bivalves reached greatest sizes in the coarse shallow zones. At the broadest scale, zones did not appear to represent homogeneous assemblages, due largely to a variable response of species to the environment at a location scale. Overall, specles richness tended to increase from fine to coarse sediment, except at the very shallow coarse sediments in the southern zone, where low numbers of species were found.

“…Opportunistic species are reported to show poor Present address: Biology Department, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA competitive ability for resources (Grassle and Grassle, 1974), high mortality due to predation (Sanders et al, 1980) or to inadvertent destruction through the activities of other species (Levinton and Stewart, 1982), and low recruitment due to inhibition of settlement (Woodin, 1976;Richter and Sarnthien, 1977;Zajac and Whitlach, 1982b). While the mechanisms of interaction are diverse, there is an implied trade-off; a species can either rapidly utilize newly opened habitat or resist the effects of biotic interactions, but cannot do both.…”

Section: Introductionmentioning

confidence: 99%

Laboratory experiments on the effects of a gastropod (Hydrobia totteni) on survival of an infaunal deposit-feeding polychaete (Capitella capitata)

Petraitis¹

1984

Many species which quickly colonize newly disturbed patches have the potential for rapid reproduction and show broad physiological tolerances. Often these species are uncommon in older patches and it is thought predation and/or competition is the primary cause for their disappearance. As a direct test of the sensitivity of an early colonizer to other species, this study examines the effects of the snail Hydrobia totteni on the early survivorship of the polychaete Capitella capitata (species type I). Family effects (i.e. either maternal effects or genetic differences among females) account for most of the variation in survivorship from free-swimming larvae to 2 wk of age. If family effects are controlled, then survivorship of Capitella is always poorer in the presence of H. totteni. There are no detectable density-dependent or time-dependent effects.