Peter Kinner

Benthic invertebrate assemblages of Delaware Bay

During two consecutive summers, the first quantitative bay-wide survey (207 stations) of benthic invertebrates was conducted in Delaware Bay (USA). In 1972, 109 species were collected at 105 stations; and in 1973, 125 species were collected at 102 stations. A total of 169 different species were collected for both summers. The number of species and number of individuals increased with increasing salinity and increasing median grain size. These relationships were compared and were found similar to those in estuaries and bays throughout the world. Average density was 722 individuals m2, which is low compared to other estuaries. The relationship of low secondary production to pollution, macroscopic algae, sediment transport, predation, and hydrography is discussed. Deposit feeders comparised the major feeding type. Local species composition was similar to that in Chesapeake Bay, and dominant species occurred in estuaries throughout the Mid-Atlantic Bight. The benthic invertebrates of Delaware Bay were related to the cosmopolitan mode of estuarine faunas. Faunal assemblages were identified by cluster analysis. The assemblages were associated with sediment type and salinity. It was concluded that Delaware Bay comprises a mosaic of animal assemblages, some of which have relatively sharp boundaries similar to classical level bottom type communities, whereas the boundaries of others are almost impossible to detect, and these represent species distributed along an environmental continum.

Seasonal changes in feeding types of estuarine benthic invertebrates from delaware bay

Abstract One hundred and fifty quantitative benthic invertebrate samples were collected during five consecutive seasonal cruises (May 1974 to May 1975) in a small area of southwestern Delaware Bay. The samples were divided into four site groups: 1. 1) clean, fine sand 2. 2) coarse sand 3. 3) serpulid tubes; and 4. 4) muddy sand. Each group was characterized by percentage composition of feeding type, dominance, density, and an evenness measure or scaled standard deviation (SDN). Based on earlier work in a small, relatively homogeneous area, SDN had been used to relate diversity to resource sharing in a benthic community; and so this measure was applied to a larger, more heterogeneous area. Present classifications of feeding types are inadequate for an assessment of resource sharing in mixed habitats. Significant problems in analysis emerge because of insufficient data on individual feeding habits. Similar problems were noted in research from European coastal waters. The seasonal effect of meroplankton on the structure and function of benthic assemblages was inferred from plankton samples. These samples suggested explanations for heavy recruitment of a few dominant species. Finally, the biota of the four groups was compared with other assemblages in the mid-Atlantic Bight which show some strong similarities.

Benthic faunal assemblages off the Delmarva Peninsula

Abstract Based on 90 quantitative samples collected May and November 1973 the species composition, distribution and abundance of benthic invertebrates on the inner continental shelf off the Delmarva Peninsula (38 ° 23′N and 47 ° 15′W) were determined. A total of 149 species were identified. Thirty-five were found only in May and 65 only in November. In May the fauna consisted primarily of nearly equal numbers of polychaete and crustacean species with an increase in the number of polychaete species and a decrease in crustacean species in November. In May the polychaetes Goniadella gracilis and Lumbrineris acuta were co-dominants (Biological Index Value) while in November the archiannelid Polygordius sp. was strongly dominant. There was essentially no change in the number of deposit-feeding individuals from May to November. Even though the trophic structure remained unchanged, the species changed and the total number of individuals increased by 50% from May to November. The Delmarva assemblage was briefly compared to benthic assemblages closer to the Delaware Bay estuary. Comparison revealed the importance of estuaries and ridge and swale microtopography in influencing the distribution of the shelf fauna. It was concluded that the Delmarva assemblage belonged to a clean sand fauna which occurs throughout the inner continental shelf of the Middle Atlantic Bight. A number of species representing polychaetes, crustaceans, mollusks and echinoderms were proposed as characteristic sand fauna species.

Seasonal fluctuations in coastal benthic invertebrate assemblages

Abstract Two hundred and eighty-eight quantitative benthic invertebrate samples were collected during four quarterly sampling cruises at two areas off the Delaware coast. Species composition, species dominance (abundance and frequency of occurrence), density, and species evenness were compared. Based on cluster analysis three species-site groups emerged: (1) a high energy shoal assemblage characterized by a year-round suite of haustoriids and a few bivalves, (2) a mixed hard bottom-sand assemblage that featured marked seasonal dominance of Mytilus edulis with a variety of seasonal epifaunal and infaunal species, (3) a medium sand assemblage with a variety of seasonal infaunal species. Similar assemblages have been recognized off New Jersey and New York. Seasonal fluctuations in undisturbed coastal invertebrate assemblages can be so marked that many environmental impact studies are inadequate to assess the effects of human activities.

Evaluation of sludge dumping off Delaware Bay

Abstract Sewage sludge from Philadelphia and Camden has been dumped off the mouth of Delaware Bay since 1961. Local residents have claimed that sludge is washed ashore, is a health hazard and has impoverished the fauna of the seabed in the area. In the survey reported here, an assessment has been made of the composition and abundance of the benthic marine fauna of the dumping grounds. The results suggest that dominant species of the area are changing as particulate organic matter accumulates.

Polychaete population dynamics and production in the New York bight associated with variable levels of sediment contamination

Abstract Present approaches to assessing effects of anthropogenic disturbances on marine benthic macrofauna are mostly based on community or population structure analysis. There are limited studies on functional effects, e.g., to growth or production. This paper examines the population dynamics, growth curves, and production rates for nine common species of surface-deposit feeding or carnivorous polychaetes at three locations in the contaminated New York Bight apex. These locations were environmentally similar, except for variable levels of sediment organic carbon (TOC) and toxic chemicals (trace metals, PCBs, and polyaromatic hydrocarbons). The results suggest little difference in the relative growth patterns of these species, with variable production or production to biomass ratios (P:B) responses between the locations and their variable contamination levels. The range ofP:B ratios were similar to those reported elsewhere for the same or related species in usually less contaminated areas. This suggests ...

Effect of spoil disposal on benthic invertebrates

Abstract Hydraulic dredging and spoil disposal behind the inner breakwater in Delaware Bay has an impact over several kilometres from the site of operations. While dissolved oxygen and the density of animals fell in the areas immediately affected, the total impact of this operation appears to have been small. There may even have been some recruitment of animals to the spoil areas after the operations.

The use of species abundance estimates in marine benthic studies

Abstract The application of species abundance estimates, commonly used in terrestrial plant ecology, to marine benthic dredge data is advocated. Two possible scales were tested for their ability to measure adequately the structure of an assemblage by computing measures of evenness diversity McNaughtons dominance index, and Morisitas index of dispersion using both real counts obtained from grab samples and these counts transformed into the two respective abundance estimates. It is concluded that species abundance estimators, when applied to grab or dredge data result in significant savings in sample processing time with only a minimal loss of information about assemblage structure.

Baseline studies of delaware ocean outfall sites

Abstract A quarterly sampling programme was conducted during 1973–1974 off the coast of Delaware to provide an environmental baseline for two ocean sewage outfalls. Extensive physical measurements and water quality data, together with biological data (fish, invertebrates, bacteriological samples), were collected. Based on this research the design of sewage treatment for one of the outfalls was improved.