Spatial distribution and population characteristics of the invasive cladoceran Cercopagis pengoi in the Polish coastal zone seven years after the first record

The presented results provide the first comprehensive description of the C. pengoi population and document new records of its expansion to the west in the Polish coastal zone of the Baltic Sea. In June–August 2006, C. pengoi was observed for the first time continuously for nine successive weeks in a broad range of the water temperature and salinity. Its abundance fluctuated from some to several hundred specimens per cubic meter. In July the species was much more abundant in the water far from the coast, whereas in August its maximum density was observed at the most shallow station. The population of C. pengoi occupied the whole water column, from the surface water to 80 m depth, its vertical distribution was not uniform. C. pengoi was represented by specimens from all age-specific morphological stages (BS I–III). The largest part of the population (up to 81.53%) was composed of juvenile specimens (BS I and II). Parthenogenetic females in the second instar constituted the majority of BS II specimens.

A Broad Review of Variability and Persistence in the Northumberland Benthic Fauna – 1971–85

The long-term monitoring of two stations, 55 and 80 m depth, from 1971 to 1985 shows clear evidence of periods of stability interspersed with periods of change. These periods were identified by several different multivariate methods and persistence stability was quantified by the use of a between years similarity index. A short period of change at the shallow station, 1972–3, was followed by a prolonged period of stability 1974–80. The period 1981–3 witnessed a second period of change with rising total numbers and biomass with some evidence of a downward reversal in 1984–5. The deep station exhibited an essentially similar response except that the stable period 1974–80 was broken into two sub-periods 1974–6 and 1978–80 due to sequential changes in the dominant species which were regarded as evidence of biological interaction with the activities of the polychaete Ophelina acuminata possibly playing a key role. The shallow station showed little evidence of biological interaction and the majority of the species have exhibited similar responses throughout. The general rise in numbers and biomass at both stations is regarded as evidence of intermittent changes in organic flux to the bottom from the water column. The winter temperature fluctuations were shown to have short-term, but significant, effects on the diversity of the communities, bringing about year to year changes in the equitability and dominance.

Sedimentation of Organic Matter in St. Margaret’s Bay, Nova Scotia

Sediment traps were placed at two sites in St. Margaret’s Bay. At a deep station (70 m), traps were placed 5 m and 10 m above the bottom; at a shallow station (10 m), six traps were placed between 45 and 197 cm above the bottom. Total catch averaged 118 g C m−2yr−1 at the deep station and 134 g C m−2yr−1 at the shallow station. The most probable source of the organic matter was detritus derived from seaweeds and seagrasses, but the most probable source of inorganic material was bottom sediment. It is suggested that the traps were taking bottom sediment resuspended from shallow water, enriched by detritus from seaweeds and seagrasses.

Macrobenthic Ecology of a Sawdust-Bearing Substrate in the Penobscot River Estuary (Maine)

The macrobenthos of sawdust-bearing substrates in the Penobscot River estuary (Maine) were sampled bimonthly from January through November 1968. The polychaete Scolecolepides viridis and the bivalves Macoma balthica and Mya arenaria dominated the sandy sediments of the shallow station. Prionospio malmgreni and Corophium volutator were dominant in the granular substrate of the deeper station. The population of the shallow station (1-m depth, mean low water) was seasonally more stable and had a higher mean monthly bio-index (number of individuals/number of species) than that of the deeper station (6-m depth, mean low water).