Benthic community structure, diversity, and productivity in the shallow Barents Sea bank (Svalbard Bank)

The Barents Sea is among the most productive areas in the world oceans, and its shallow banks exhibit particularly high rates of primary productivity reaching over 300 g C m^?2year^?1. Our study focused on the Svalbard Bank, an important feeding area for fishes and whales. In order to investigate how benthic community structure and benthic secondary production vary across environmental gradients and through time, we sampled across the bank and compared results with a similar study conducted 85 years ago. Considerable variability in community structure and function across bank corresponded with differences in the physical structure of the habitat, including currents, sedimentation regimes and sediment type, and overlying water masses. Despite an intensive scallop fishery and climatic shifts that have taken place since the last survey in the 1920s, benthic community structure was very similar to that from the previous survey, suggesting strong system resilience. Primary and secondary production over shallow banks plays a large role in the Barents Sea and may act as a carbon subsidy to surrounding fish populations, of which many are of commercial importance.     

Preparing for ISO 14000: An assessment guide

With ISO 14000 expected to roll out in 1996, have you begun to evaluate how well your current environmental management policy, programs, procedures, and objectives conform to published national and evolving global Environmental Management System (EMS) standards?. The ISO expects to adopt a final standard by mid-1996 which specifies requirements for an EMS (e.g., ISO 14001). In addition, national EMS standards have already been developed and published by organizations such as The British Standards Institute and, in the United States, NSF International, for example, BS 7750 and NSF 110–1995, respectively. This article shows how managers can begin assessing their operations to prepare for these new standards and improve overall environmental performance.     

Impact of cadmium on food utilization of the Indian major carp,Catla catla (Ham)

Catla catla, under the sublethal stress of cadmium exhibited depletion in food utilization parameters and it was concentration dependent. Heavy metal intoxication was found to exhibit reduction in biomass.     

Dynamics of shallow-water populations of Octopus dofleini

Octopus dofleini (Walker) is a common inhabitant of shallow subtidal communities in the Northeast Pacific. The abundances of octopuses at two sites monitored since 1977 have fluctuated greatly during this period. The populations reached high abundances in mid-summer and, during some years, mid-winter. The highest abundances at the two sites did not coincide. There was a constant influx of new octopuses into both study sites, with the greatest immigration occurring in early summer. The octopuses captured spanned a wide range of weights every month, with no clear size classes or seasonal trends in size. The weights of newly-captured octopuses, however, did differ between the sexes and seasons: males weighed more on the average than females, and male weight decreased from winter to fall while female weights did not change O. dofleini appeared to recruit throughout the year; the smallest octopuses occurred between May and November and the greatest number of small octopuses was found in July and August in most years. Females predominated at both study sites throughout the year. However, males predominated among octopuses caught in traps at nearby locations, suggesting that the skewed sex ratios were due to behavioral differences between the sexes.     

Abusive according to whom? Manager and subordinate perceptions of abusive supervision and supervisors' performance

Recognizing that supervisor–subordinate dyads exist within a broader organizational hierarchy, we examine how the individual's role within the organizational hierarchy influences perceptions of abusive supervision. Specifically, we examine how supervisors' abusive behaviors are perceived by abusive supervisors' managers as well as abusive supervisors' subordinates. Drawing on role theory, we propose that these perceptions will differ. Further, we suggest that these differences will be reflected in different relationships between manager-rated abusive supervision and subordinate-rated abusive supervision and managers' evaluations of supervisor performance. Results from manager–supervisor–subordinate triads indicate differences between managers' and subordinates' view of abusive supervision. Further, managers' perceptions of abuse were related to supervisors' in-role performance, whereas subordinates' perceptions of abuse were related to workgroup performance. In Study 2, we replicate these findings and expand our investigation to an examination of supervisors' contextual performance. Additionally, we examine another contextual characteristic—aggressive climate—and demonstrate it influences how abusive supervision relates to managerial evaluations of supervisor performance. Future research and managerial implications are discussed.     

Influence of an artificial reef on the surrounding infaunal community

Artificial reefs have been constructed throughout the world, but their effects on adjacent soft-bottom communities are largely unknown. In December 1986, we investigated the influence of Pendleton Artificial Reef (PAR) in Southern California on the abundance of infauna in the surrounding sand bottom. PAR was constructed in 1980 of quarry rock placed in eight piles, or modules. The artificial reef altered the grain-size distribution of sediments around the reef; sediments close to the modules were coarser than those 10 or 20 m away from the modules. Densities of one of the two most common species, the polychaetePrionospio pygmaeus, were lower near the reef, perhaps due to foraging by reef-associated predators or because the habitat near the reef was less suitable. We found no evidence that foraging by reef-associated fishes caused a widespread reduction in infaunal densities near the reef, and in fact the other most common taxon,Spiophanes spp., had higher densities near the reef. The most conspicuous effect of the artificial reef concerned the tube-dwelling wormDiopatra ornata, which only occurred in close association with the modules. In addition, total infaunal density and the densities of decapods, echinoderms and sipunculids were higher withinD. ornata beds than outside the beds. These results indicate that the densities of some species were enhanced, and others depressed, around the reef, but that the overall effect of the artificial reef on the surrounding infauna was limited to a small area near the modules.     

Estimate of removal rate ofNereis virens (Polychaeta: Nereidae) from an intertidal mudflat by gulls (Larus spp.)

The feeding behavior of herring gulls (Larus argentatus), ringed-billed gulls (L. delawarensis) and great blackbacked gulls (L. marinus) on an intertidal mudflat in Maine, USA, was investigated. Remains of fish, mussels, crabs, insects, and the polychaeteNereis virens were recovered from gull feces. Forty-three percent of the fecal samples containedN. virens jaws, setae, or both. A comparison of jaws from fecal material and from worms collected from the natural community demonstrates that gulls preferentially preyed upon larger worms. Feeding was largely confined to 3 h around low tide, and birds fed mostly in the low intertidal and below mean low water where the largest worms were located. Individual birds remained on the flat for a mean of 28.0 min and consumed a mean of 19.2 worms per visit. It was calculated that gulls remove a mean of 808 largeN. virens from the flat per tide from June to October, representing an estimated 0.04% of the standing crop of largeN. virens.     

Modeling mercury fluxes and concentrations in a Georgia watershed receiving atmospheric deposition load from direct and indirect sources

This paper presents a modeling analysis of airborne mercury (Hg) deposited on the Ochlockonee River watershed located in Georgia. Atmospheric deposition monitoring and source attribution data were used along with simulation models to calculate Hg buildup in the subwatershed soils, its subsequent runoff loading and delivery through the tributaries, and its ultimate fate in the mainstem river. The terrestrial model calculated annual watershed yields for total Hg ranging from 0.7 to 1.1 microg/m2. Results suggest that approximately two-thirds of the atmospherically deposited Hg to the watershed is returned to the atmosphere, 10% is delivered to the river, and the rest is retained in the watershed. A check of the aquatic model results against survey data showed a reasonable agreement. Comparing observed and simulated total and methylmercury concentrations gave root mean square error values of 0.26 and 0.10 ng/L, respectively, in the water column, and 5.9 and 1 ng/g, respectively, in the upper sediment layer. Sensitivity analysis results imply that mercury in the Ochlockonee River is dominated by watershed runoff inputs and not by direct atmospheric deposition, and that methylmercury concentrations in the river are determined mainly by net methylation rates in the watershed, presumably in wetted soils and in the wetlands feeding the river.     

LANDSCAPE‐SCALE ANALYSIS AND MANAGEMENT OF CUMULATIVE IMPACTS TO RIPARIAN ECOSYSTEMS: PAST,PRESENT, AND FUTURE1

ABSTRACT: Analyses of cumulative impacts to riparian systems is an important yet elusive goal. Previous analyses have focused on comparing the number of hectares impacted to the number of hectares restored, without addressing the loss of riparian function or the effect of the spatial distribution of impacts. This paper presents an analysis of the spatial distribution of development‐related impacts to riparian ecosystems, that were authorized under Section 404 of the Clean Water Act. Impacts on habitat structure, contiguity, and landscape context were evaluated using functional indices scaled to regional reference sites. Impact sites were mapped using GIS and analyzed for spatial associations. Positive spatial autocorrelation (i.e. clustering of impact sites) resulted from the piecemeal approach to impact assessment, which failed to prevent cumulative impacts. Numerous small projects in close proximity have resulted in adverse impacts to entire stream reaches or have fragmented the aquatic resources to a point where overall functional capacity is impaired. Additionally, the ecological functions of unaffected areas have been diminished due to their proximity to degraded areas. A proactive approach to managing cumulative impacts is currently being used in Orange County, California as part of a Corps of Engineers sponsored Special Area Management Plan (SAMP). The SAMP process is evaluating the ecological conditions and physical processes of the study watersheds and attempting to plan future development in a manner that will guard against cumulative impacts.