Opportunistic life histories and genetic systems in marine benthic polychaetes

The decline in benthic marine fauna following an oil spill in West Falmouth, Massachusetts, permitted us to follow the responses of a number of polychaete and other invertebrate species to an environmental disturbance. Species with the most opportunistic life histories increased and declined at the two stations with the greatest reduction in species diversity. The stations with an intermediate reduction in diversity showed increases and declines of somewhat less opportunistic species...

The role of colonization in establishing patterns of community composition and diversity in shallow-water sedimentary communities

To determine whether pattern and diversity in benthic sedimentary communities are set primarily at colonization or by post-settlement biological interactions, we collected faunal cores and conducted reciprocal sediment transplant experiments at a sandy and a muddy site at 12 m depth, ~3 km apart off New Jersey. Multivariate analyses of cores collected at these sites in September 1994 indicated differences in the taxa determining local pattern, with the bivalve Spisula solidissima and the polychaete Polygordius sp. being dominant at the sandy site, and oligochaetes, several polychaete species and the bivalve Nucula annulata dominant at the muddy site. Individual cores from the sandy site were significantly less diverse than those at the muddy site. Short-term experiments (3-5 d) were deployed by divers at three different times (August-September, 1994). Replicate trays (100 cm2) filled with azoic sand or mud were placed flush with the ambient seafloor at both sites. Multivariate comparisons indicated that sediment treatment in trays played a greater role in determining colonization patterns in the first experiment, site played a greater role in the second, and both variables contributed in the third. This pattern suggests that larval settlement and habitat choice played an important role in the first and third experiments, and that local transport of recently settled juveniles from the surrounding sediments was important in the second and third experiments. Sandy-site trays had significantly lower diversity than muddy-site trays, but there was no effect of sediment type in trays on diversity of colonizers. These experiments focused on small spatial scales and three short time periods, but they demonstrate that species patterns in some environments may be set by habitat selection by larvae and by juvenile colonization from the surrounding community. Post-colonization processes such as predation and competition likely play a major role for some species, but patterns of initial colonization corresponded well with those in the local community

Temporal and spatial variation in infaunal community structure in physically active continental shelf sediments at a long-term ecosystem observatory (LEO-15) off New Jersey, USA

When the LEO-15 (Long-term Ecosystem Observatory at 15-m depth) research area was designated around Beach Haven Ridge (39°27.69′ N, 74°15.81′ W) in the early 1990\u27s several stations were selected to reflect the different physical regimes and habitats present in a highly dynamic shelf environment. This study determined the composition, diversity, and abundance of infaunal communities at three contrasting stations on five dates in 1994–1995. A unique sampling scheme was used where a nested design was combined with targeted sampling by divers of benthic topographic habitat features, namely crests and troughs of sand ripples. The total number of taxa collected was 148. The majority of taxa (80%) were either ubiquitous (67 taxa, 45%) or had an apparent affinity for a single station (52 taxa, 35%). The polychaete Polygordius jouinae was numerically dominant. The three distinctive stations 2–4 km apart, the date of sampling and, somewhat surprisingly, whether or not samples were taken in adjacent crests or troughs, all contributed to the structure of LEO-15 infaunal communities. Together these three stations characterize the sediments and fauna in the LEO-15 research area and form the basis for future studies of short and longer-term changes, and of the processes and mechanisms responsible for the patterns observed

Macrofaunal response to artificial enrichments and depressions in a deep-sea habitat

To test whether colonizing macrofauna specialize on different types of small-scale patches of food and disturbance in the deep sea, sediment tray and artificial depression colonization experiments were conducted on the deep-sea floor at 900-m depth, south of St. Croix, U.S. Virgin Islands. Trays and depressions were unenriched (Unenriched Controls) or enriched with either Thalassiosira sp. or Sargassum sp. Concurrent deployment of different types of enrichment and disturbance made it possible to evaluate whether macrofauna specialize on different patches, and thus avoid species interactions that might lead to competitive exclusion. Depressions create a hydrodynamic regime that traps passive particles, allowing tests of the relative importance of active selection of different patch types versus passive deposition for abundant colonizers. After 23 d, total densities and densities of the four abundant colonizers (Capitella spp., Nereimyra punctata, Cumella sp. and Nebalia sp.) were extremely high in enriched trays, despite relatively low ambient densities. Densities in Unenriched Control Trays were very low, and did not attain ambient densities. After 24 d, total densities in all depression treatments were considerably lower than in enriched tray treatments, and only Sargassum Depression densities exceeded those in the ambient environment. Lower densities of organisms in depression treatments compared with trays and differences in densities among depression treatments suggest that the dominant colonizers were highly active and selective, and were not passively entrained in depressions. Faunal analysis indicated that trays and depressions were very different, and Sargassum Depression fauna was very different from other depression types. A strong difference was not observed between fauna in ambient sediments and Thalassiosira sp. or Unenriched Control Depressions, perhaps because Thalassiosira sp. was dropped in depressions on the sediment surface and may have been more readily available to consumers and more rapidly consumed than in trays. Thalassiosira Trays were colonized by a lower diversity fauna than Sargassum Trays, and Unenriched Control Trays were colonized by very low densities of a fauna that was comparable in diversity to the ambient community. Diversity in Sargassum Depressions was higher than in enriched trays but lower than in other artificial depressions and the ambient fauna. Thalassiosira Depressions and Unenriched Control Depressions were comparable in diversity to ambient fauna and natural depressions, which were highly diverse. These experiments suggest that fauna may respond quickly and selectively to artificial food patches and disturbance, and this fauna is different from that observed in the ambient sediment. Thus, a patch mosaic may be part of the reason for the high species diversity that is observed in deep-sea ecosystems. The different, highly diverse, fauna observed in natural depressions compared with flat ambient sediment suggests that natural analogs of these experiments have unique faunas that may contribute to the species richness of deep-sea habitats

Potential flow artifacts associated with benthic experimental gear: Deep-sea mudbox examples

In response to the growing recognition of the potential effects of near-bed hydrodynamics on various benthic processes, flume studies were conducted to document fine-scale flow patterns over several types of mudboxes that have been used to study colonization by deep-sea organisms. Mudboxes are typically filled with natural sediments or sediment treatments and placed in the field to observe how timing, larval supply and sediment composition may affect larval settlement. This study addresses potential hydrodynamic biases of mudbox structures as obstructions to the near-bed flow. Detailed velocity profiles were made over two types of “free vehicle” mudboxes that could be deployed and recovered from a surface vessel. One of these (“Old Free Vehicle”) was not designed with regard for potential hydrodynamic biases whereas the other (“New Free Vehicle”) was designed specifically to minimize flow disturbances and maintain a realistic boundary-layer flow over the mudbox sediments. Flume velocity profiles also were made over two smaller mudboxes designed to be deployed by a submersible, one (“Flush Sediment Tray”) which was designed to be placed flush with the ocean bottom, thus minimizing flow disturbance, and another (“Raised Mudbox”) which was not. Flume simulations indicated that the Old Free Vehicle and the Raised Mudbox cause considerable disturbance to the near-bed flow regime; flows over the mudbox sediment surface differed markedly from those predicted for the natural seabed and those observed over the flume bed in the absence of the mudboxes. Flow accelerations, growing secondary boundary layers and eddy formation were observed over these mudbox sediments, and vertical velocity profiles varied considerably in the along-channel direction. The alternative mudbox designs (New Free Vehicle and Flush Sediment Tray) were largely successful in reducing or eliminating these flow artifacts. Boundary-layer flows over both the New Free Vehicle and the Flush Sediment Tray were much more uniform, and velocity profiles over the sediment surfaces were very similar to those in the empty flume channel and those predicted for a natural deep-sea habitat. In addition, there was no evidence of eddy formation and other major flow disturbances. These flume studies underscore the benefit of considering potential hydrodynamic effects in designing benthic experimental sampling gear to reduce potential flow disturbances that may bias data collections and confound data interpretation

The West Falmouth oil spill : persistence of the pollution eight months after the accident

A spill of 650,000-700,000 liters of #2 fuel oil has contaminated the coastal areas of Buzzards Bay, Mass. The present report summarizes the results of our continuing chemical and biological study which were available at the end of May 1970, more than eight months after the accident. The effects of environmental exposure on the composition of the oil are discussed; many analytical parameters are sufficiently stable to permit continued correlation of the oil remaining in sediments and organisms with the fuel oil involved in the spill. Oil from the spill is still present in the sediments, inshore and offshore and in the shellfish. A further spread of the pollution to more distant offshore regions has occurred during midwinter; as a result, the pollution now covers a much larger area than immediately after the accident. The first stages of biological (presumably bacterial) degradation of the oil are now evident especially in the least polluted regions; however, it has depleted predominantely the straight and branched chain alkanes. The more toxic aromatic hydrocarbons are resistant; as a result, the toxicity of the oil has not been diminished. Where oil can be detected in the sediments there has been a kill of animals; in the most polluted areas the kill has been almost total. Shellfish that survived the accident have taken up the fuel oil. The 1970 crop of shellfish is as heavily polluted as was last year’s crop. Oysters transplanted to unpolluted water for as long as 6 months retained the oil without change in composition or concentration.Submitted to the Office of Naval Research under Contract ONR N00014-66-C0241; NR 083-0043 and partially supported by the Federal Water Quality Act Grant 18050-EBN3 and with the National Science Foundation Grant GA-1625

Anatomy of an oil spill : long-term effects from the grounding of the barge Florida off West Falmouth, Massachusetts

Author Posting. © Yale University, 1980. This article is posted here by permission of Yale University for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 38 (1980): 265-380.To determine carefully the effects on the marine and estuarine benthos of Number 2 fuel oil spilled by the barge FLORIDA off West Falmouth, Massachusetts, we sampled for many months along an onshore-offshore gradient of pollution, and less intensively at unoiled sites. Analyses of hydrocarbons established that pollution was greatest and most persistent in the intertidal and subtidal zones of Wild Harbor River, less severe in degree and duration at stations farthest from shore. A variety of concurrent analyses showed that disturbance of the fauna was most severe and longest lasting at the most heavily oiled sites, and least severe but perceptible at lightly oiled stations. Patterns of disturbance were not related to granulometry of the sediments. Plants, ctustaceans, fish, and birds suffered both high mortality immediately after the spill, and physiological and behavioral abnormalities directly related to high concentrations of the fuel oil. Five years after the spill its effects on the biota were still detectable, and partly degraded #2 fuel oil was still present in the sediments in Wild Harbor River and estuary.Our study was partially supported by the Federal Water Pollution Control Contract 15080, the Environmental Protection Agency Grant No. R80100102 and Massachusetts Division of Water Pollution Control primarily during the initial three years and by the Woods Hole Oceanographic Institution at specific key periods

Vertical distribution of bivalve larvae along a cross-shelf transect during summer upwelling and downwelling

Abstract Previous time-series studies of meroplankton abundances in the LEO-15 research area off Tuckerton, New Jersey, USA (39°28¢N, 74°15¢W) indicated shortlived (6-12 h) pulses in larval surfclam (Spisula solidissima Dillwyn) concentration often associated with the initiation of downwelling. To examine possible larval surfclam (and other bivalve) concentrating mechanisms during upwelling and downwelling, six sets of adaptive mobile zooplankton pump samples were taken in July 1998 at different depths at five to six stations along a 25-km transect perpendicular to the coastline and crossing Beach Haven Ridge at LEO-15. Sampling was guided by near real-time, satellite imagery of sea surface temperature overlain by sea surface currents from a shore-based ocean surface current radar (OSCR) unit. A Seabird CTD on the mobile pump frame near the intake provided information on thermocline depth, and sampling depths were adjusted according to the temperature profiles. Near shore, the thermocline was tilted down during downwelling, and up during upwelling. The highest concentrations of surfclam larvae occurred near the bottom at a station near Beach Haven Ridge during downwelling, and just above the thermocline 3 km further offshore during well-developed upwelling. For other bivalve taxa, the larvae were concentrated near the thermocline (Anomia simplex Orbigny and Pholadidae spp.) or concentrated upslope near the bottom (Mytilidae spp.) during upwelling, and the larvae were concentrated near the bottom or were moved downslope during downwelling. Donax fossor Say larvae were found near the surface or above the thermocline during upwelling and downwelling. The general patterns of larval bivalve distribution appear to be influenced by water mass movement during upwelling and downwelling. The larval concentration patterns of individual species are likely a consequence of advection due to upwelling and downwelling circulation, vertical shear in the front region, species-specific larval behaviors, and larval sources

Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique “pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new bylaws as the Manila clam is spreading to other protected estuaries in the region