Oliver (x) ›
The level of agreement among experts applying best professional judgment to assess the condition of benthic infaunal communities,
Benthic infaunal communities are frequently used to assess aquatic environmental condition, but interpretation of benthic data is often subjective and based on best professional judgment. Here, we examine the repeatability of such assessments by providing species-abundance data from 35 sites to 9 independent benthic experts who ranked the sites from best to worst condition. Their site rankings were highly correlated, with an average correlation coefficient of 0.91. The experts also evaluated the sites in terms of four condition categories: (1) unaffected, (2) marginal deviation from reference, (3) affected, or (4) severely affected. At least two-thirds of the experts agreed on site categorization for 94% of the samples and they disagreed by more than one category for less than 1% of the assessment pairs. The experts identified seven parameters used in making their assessments, with four of those parameters (dominance by tolerant taxa, presence of sensitive taxa, species richness, and total abundance) used by all of the experts. Most of the disagreements in site categorization were due to philosophical rather than technical differences, such as whether the presence of invasive species indicates a degraded community. Indices are increasingly being used as an alternative to best professional judgment for assessing benthic condition, but there have been inconsistencies in how sites are selected for validating such indices; the level of agreement found among experts in this study suggests that consensus expert opinion can be a viable benchmark for such evaluations. © 2007 Elsevier Ltd. All rights reserved., Cited By (since 1996):29, Invertebrates, ,
Weisberg, Thompson, Ranasinghe, Montagne, Cadien, Dauer, Diener, Oliver, Reish, Velarde, Word
Sedimentation and composition of wall communities in Alaskan fjords,
The effects of suspended sediments on the composition of wall communities in Alaskan fjords were investigated by quantitative assessment of underwater photo-quadrats. In fjords with actively retreating tidewater glaciers, suspended sediment levels were extremely high at the heads and were exponentially lower at the mouths. Fjords without glaciers had low suspended sediment levels throughout. The per cent cover and number of species were lowest where sedimentation was highest, at the heads of glacial fjords. Here the wall communities were dominated by a sparse cover of small serpulid worms. Richer communities comprising mostly algae, sponges, hydroids, bryozoans, tunicates and brachiopods were found in fjords without glaciers, and at the mouths of glacial fjords. There was a positive correlation between water clarity and community composition along a gradient from heads to the mouths of fjords with high suspended sediment levels., Cited By (since 1996):3, Invertebrates, Ecology, CODEN: POBID, ,
Carney, Oliver, Armstrong
A framework for investigating general patterns of benthic β-diversity along estuaries
The description of major patterns in beta (. β) diversity is important in order to understand changes in community composition and/or richness at different spatial and temporal scales, and can interrogate processes driving species distribution and community dynamics. Human impacts have pushed many estuarine systems far from their historical baseline of rich, diverse, and productive ecosystems. Despite the ecological and social importance of estuaries, there has not yet been an attempt to investigate patterns of β-diversity and its partitioning along estuarine systems of different continents. We aimed to evaluate if benthic assemblages would show higher turnover than nestedness in tropical than in temperate systems, if well-known impacted estuaries would show greater nestedness than less polluted systems, and to propose a conceptual framework for studying benthic macrofauna beta diversity along estuaries. We analyzed subtidal benthic macrofaunal data from estuaries in Brazil, USA and France. We estimated alpha (. α), beta (. β) and gamma (. γ) diversity for each sampling time in each system, investigated patterns of β -diversity as multivariate dispersion and the partitioning (nestedness and replacement) of β-diversity along each estuary. There was a decrease in the α-diversity along marine to freshwater conditions at most of the estuaries and sampling dates. Beta diversity as multivariate dispersion showed high variability. Most of the estuaries showed a greater proportion of the β-diversity driven by replacement than nestedness. We suggest a conceptual framework for estuaries where relatively pristine estuaries would have their β-diversity mostly driven by replacement while impacted estuaries subjected to several anthropogenic stressors would show total nestedness or total replacement, depending on the stress.
Barros, Blanchet, Hammerstrom, Sauriau, Oliver
Intense and localized benthic marine pollution around McMurdo Station, Antarctica,
Cited By (since 1996):61, CODEN: MPNBA, Benthic sediments and animals are highly modified by human activities at McMurdo Station, the largest human settlement in Antarctica. The quantity of anthropogenic debris, contamination of marine sediments with hydrocarbons and metals, and gross changes in benthic communities are largely confined to Winter Quarters Bay, adjacent to the former dump site and the ice dock used by visiting ships. Levels of purgeable hydrocarbons in bay sediments are as high as 4500 ppm. Metal levels are mostly high within the bay, but are not greater than in the most polluted temperate habitats. Levels of anthropogenic chemicals are significantly higher in the back bay compared to stations established at different distances from the bay (along three potential contamination gradients), including reference sites many kilometres away. There are significant negative correlations between the total number of infauna or epifauna and the concentrations of hydrocarbons and most metals in sediments. The few animals living in the back bay are motile polychaete worms with opportunistic life histories, primarily Capitella capitata antarcticum and Ophryotrocha claparedii. Fortunately, the local physical setting apparently permits little transport of contaminated sediments from the bay, which is flanked on one side by a large submarine ridge and on the other by Hut Point. Hut Point also protects the bay from oceanic conditions. The back bay is over 30 m deep and the ridge top is only 18 m deep. The gradient of chemical and community change is extremely steep, but there are observable ecological impacts outside the bay along the front of the station. Although most historical inputs of pollution are removed or reduced and continued cleanup is planned, Winter Quarters Bay may require many decades to recover., ,
Lenihan, Oliver, Oakden, Stephenson
Benthic changes during 10 years of organic enrichment by McMurdo Station, Antarctica,
A benthic habitat along the coast of McMurdo Station in the Ross Sea, Antarctica is enriched by sewage from the station and altered by hydrocarbons and heavy metals in an adjacent historic dumpsite. We report on 10 years of change in the benthic communities from 1988 to 1998 and compare enrichment effects at Australia's Casey Station, East Antarctica. Despite being 14 km apart, reference communities upcurrent and downcurrent of McMurdo Station remained closely similar over time, dominated in all years by a tube building polychaete, Spiophanes tcherniae. The community bordering McMurdo Station was generally a third as abundant as communities at the reference sites over the decade of sampling, although diversity was as high or higher, except in the most contaminated areas. In 1992, organic enrichment of the outfall community intensified and within the year, the opportunistic polychaetes Aphelochaeta sp., Ophryotrocha notialis, Capitella perarmata, and Leitoscoloplos kerguelensis became dominant. Since 1996, two of the three enriched communities have increased in resemblance to the reference communities. Given the observed responsiveness of the benthos to the outfall so far, further changes are anticipated within the year following implementation of sewage treatment in 2003. Organic enrichment by McMurdo Station has had a greater impact on benthic community structure than at Australia's Casey Station. © 2004 Elsevier Ltd. All rights reserved., Cited By (since 1996):37, CODEN: MPNBA, ,
Conlan, Kim, Lenihan, Oliver
Distribution patterns of benthic microalgal standing stock at McMurdo Sound, Antarctica,
During the austral summer of 1975-76 and winter of 1977 benthic and water column chlorophyll a and phaeopigments were measured at several sites along the east and west sides of McMurdo Sound, Antarctica. Estimates of in situ primary productivity were made at some McMurdo Sound locations. Additionally, water column samples were collected at 5 stations in the Ross Sea during January, 1976. Standing stock data are analyzed to identify seasonal and spatial patterns. Variability in algal standing stock was related to ambient light levels and appeared to be mediated by ice and snow cover whereby the highest algal standing stock was present under high light conditions (low ice and snow cover, shallow water, summer). Differences in published benthic invertebrate densities appear to be closely allied to differences in benthic primary production, and less so to in situ planktonic ice microalgal production. © 1986 Springer-Verlag., Cited By (since 1996):49, Seaweeds, Antarctica, CODEN: POBID, ,
Dayton, Watson, Palmisano, Barry, Oliver, Rivera
Recruitment, Growth and Mortality of an Antarctic Hexactinellid Sponge, Anoxycalyx joubini
Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future. © 2013 Dayton et al., Cited By (since 1996):4, Art. No.: e56939, Downloaded from: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0056939 (16 June 2014).
Dayton, Kim, Jarrell, Oliver, Hammerstrom, Fisher, O'Connor, Barber, Robilliard, Barry, Thurber, Conlan
Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding,
Swarms differed in their geographic extent, local biomass, and life stages of swarming individuals and thus in their availability to feeding Eschrichtius robustus. Immature amphipods apparently swarmed for dispersal, whereas cumaceans probably swarmed for mating. All life stages of the hyperbenthic mysids occurred above the sea floor. Although the geographic spread of mysid swarms and shrimp communities was much greater than for the amphipod and cumacean swarms, the latter swarmed in denser patches to produce higher local biomass. Crustacean swarms are important in describing the geographic patterns of gray whale feeding from the Chukchi Sea to Baja California. The primary feeding ground is in the S Chukchi Sea and especially the N Bering Sea, where gray whales suck infaunal amphipods from fine sand. The primary feeding ground is divided into a relatively deep zone (>20 m), where tube-dwelling ampeliscid amphipods are the major prey, and a shallow zone (<20 m), where burrowing pontoporeid amphipods dominate. The secondary feeding ground is in the S Bering Sea along the E Alaska Peninsula and adjacent Alaskan mainland where shrimp and mysids are the major prey. -from Authors, Cited By (since 1996):16, Invertebrates, Marine Mammals, Birds & Turtles, ,
Kim, Oliver
Influence of sea otters on soft-bottom prey communities in southeast Alaska,
Enhydra lutris forage primarily on bivalve prey, especially the butter clam Saxidomus giganteus and dramatically reduce infaunal bivalve and sea urchin Strongylocentrotus spp. prey populations. Bivalve prey abundance, biomass and size were negatively correlated with sea otter occupancy. Otter-cracked shells of the deep-burrowing clams Tresus capax and Panope abrupta were rarely found, even at otter foraging sites where these clams accounted for the majority of available prey biomass, suggesting that these species have a partial depth refuge from otter predation. Infaunal bivalves provide a more sustainable food base than do sea urchins., Cited By (since 1996):19, , , Downloaded from: www.int-res.com/articles/meps/82/m082p103.pdf (9 June 2014).
Kvitek, Oliver
Effect of sample area and sieve size on benthic macrofaunal community condition assessments in california enclosed bays and estuaries,
Benthic macrofauna are used extensively for environmental assessment, but the area sampled and sieve sizes used to capture animals often differ among studies. Here, we sampled 80 sites using 3 different sized sampling areas (0.1, 0.05, 0.0071m2) and sieved those sediments through each of 2 screen sizes (0.5, 1mm) to evaluate their effect on number of individuals, number of species, dominance, nonmetric multidimensional scaling (MDS) ordination, and benthic community condition indices that are used to assess sediment quality in California. Sample area had little effect on abundance but substantially affected numbers of species, which are not easily scaled to a standard area. Sieve size had a substantial effect on both measures, with the 1-mm screen capturing only 74% of the species and 68% of the individuals collected in the 0.5-mm screen. These differences, though, had little effect on the ability to differentiate samples along gradients in ordination space. Benthic indices generally ranked sample condition in the same order regardless of gear, although the absolute scoring of condition was affected by gear type. The largest differences in condition assessment were observed for the 0.0071-m2 gear. Benthic indices based on numbers of species were more affected than those based on relative abundance, primarily because we were unable to scale species number to a common area as we did for abundance. © 2010 SETAC., Cited By (since 1996):3, Invertebrates, ,
Hammerstrom, Ranasinghe, Weisberg, Oliver, Fairey, Slattery, Oakdeny
Scavenging and other feeding habits of lysianassid amphipods (Orchomene spp.) from McMurdo Sound, Antarctica,
The distribution and scavenging habits of the two most abundant lysianassid amphipods in McMurdo Sound differ markedly. Orchomene plebs lives primarily in deep water (>100 m), where planktonic and benthic food is sparser and scavenging events are less common and predictable than in shallower water. Orchomene plebs is common in shallow areas (<100 m) only under the Ross Ice Shelf and along the western McMurdo Sound. Here Weddell seals frequent tidal cracks in which they discard carrion and defecate; otherwise food is scarce. Orchomene pinguides lives on shallow (<10 m) wave-cut benches that are rich in food along the eastern McMurdo Sound. They, along with other omnivorous invertebrates which scavenge the food-rich eastern sound benches, are rare from shallow water along the western sound. The eastern benches are bathed by dense plankton blooms and harbor a high biomass of benthic diatoms and invertebrates. Scavenging events there were observed throughout the year. Orchomene plebs is larger and more motile, and came to laboratory carrion and baited field traps more rapidly and in greater numbers than O. pinguides. The crop contents of O. plebs contained only amorphous organic matter that suggested a scavenging habit. Crops of O. pinguides contained not only amorphous organic matter but also invertebrate prey, especially planktonic copepods that impact the bottom during winter. © 1986 Springer-Verlag., Cited By (since 1996):33, CODEN: POBID, ,
Slattery, Oliver
Side-scan sonar estimates of the utilization of gray whale feeding grounds along Vancouver Island, Canada,
Infaunal prey communities and gray whale feeding excavations were found at three sites along the west coast of Vancouver Island: Ahous Bay, Pachena Bay and Port San Juan. Side-scan sonar records indicated that whales disturbed up to 36% of the sea floor. The mean percentage of the bottom covered with feeding excavations was >17% in each of the three feeding grounds. There was a positive relationship between the biomass of ampeliscid amphipod prey and the total quantity of prey consumed by gray whales from the three feeding grounds. There also was considerable annual variation in the size of feeding excavations, the total area covered by excavations, and the dispersion of excavations over the entire prey community during 3 years of observations at Pachena Bay. In general, two types of gray whale feeding records occurred in the Ampelisca tube mats. One record was composed of large complex excavations (mean > 20.5 m2): the other contained only small features (mean < 4 m2). Gray whales expanded the small feeding excavations into large, complex features by feeding along the edges of existing depressions. Edge feeding may increase the energy yield per dive as whales avoid low biomass areas inside existing excavations. It may also require less energy to lift the bottom by suction along the edge of an exposed tube mat. Gray whale feeding suspended over 1000 m3 of sediment per day. Since sediment grain size was coarser inside feeding excavations (mean = 0.160 mm) compared to outside (mean = 0.124 mm), gray whales may help to maintain the mud poor fine sand habitat of its primary benthic prey, Ampelisca, by winnowing away finer sediments. Certain infaunal prey types (e.g. onuphid polychaetes) are less resilient to gray whale predation than others (e.g. Ampelisca) as a result of their local distribution patterns and life history. © 1986., Cited By (since 1996):12, Marine Mammals, Birds & Turtles, CODEN: CSHRD, ,
High species density patterns in macrofaunal invertebrate communities in the marine benthos,
Species density of macrofaunal invertebrates living in marine soft sediments was highest at the shelf-slope break (100-150m) in Monterey Bay (449 m-2). There were 337 species m-2 in the mid-shelf mud zone (80 m). There were fewer species along the slope: 205 m-2 from the lower slope (950-2000 m) and 335 m-2 on the upper slope (250-750 m). Species density was highest inside the bay (328-446 m-2) compared to outside (336-339 m-2), when examining samples at selected water depths (60-1000 m). There was little difference in local species density from 1 km of shoreline compared to regional species density along 1000 km of shoreline at both shelf and slope depths. The highest species densities worldwide in the literature are recorded along the Carolina slope in the Atlantic Ocean, where peak species density (436/0.81 m2) at 800 m and values at the largest sample areas are similar to those on the Monterey Bay shelf. We speculate that the highest species densities occur where ocean water exchanges energy with shoaling topography at the continental margin, bringing more food to the benthos -- areas such as the very productive waters in the upwelling system of Monterey Bay., Cited By (since 1996):1, ,
Oliver, Hammerstrom, McPhee-Shaw, Slattery, Oakden, Kim, Hartwell
Destruction and opportunity on the sea floor: effects of gray whale feeding,
Eschrichtius robustus are highly disruptive bottom feeders that remove infaunal invertebrate prey and sediments by suction. The response of the benthos to gray whale feeding was examined in the primary feeding grounds of the Bering Sea and in an ecological analog of these prey communities along the W coast of Vancouver Island. Large feeding excavations (often 2-20m2) were rapidly colonized by scavenging lysianassid amphipods, especially Anonyx spp. that attacked injured and dislodged infauna. Many of the attacked animals were small crustaceans (<1cm long) and polychaete worms. Anonyx spp. was 20-30 times more abundant inside fresh excavations than in the surrounding tube mat, where they dispersed within hours after the initial feeding disturbance. A smaller species of lysianassid, Orchomene minuta, invaded less rapidly and remained much longer in excavations than the larger, Anonyx spp. Within days and weeks, gray whale feeding excavations trapped organic debris. Most invading species were much more abundant in debris patches compared to debris-free areas of the same excavations. The numbers of some colonists remained elevated in disturbed areas for 2 mo., Cited By (since 1996):68, ,
Oliver, Slattery
Gray whales and the structure of the Bering Sea benthos,
The purpose of this study was to look at the effect of foraging by gray whales on the benthic community. The gray whale, the only mysticete whale which feeds mainly upon benthic organisms, relies on the amphipod crustacean assemblages of the northern Bering Sea and the Chukchi Sea for most of its annual food intake. Foraging whales leave identifiable depressions 0.6 to 3 m long in the bottom sediments in their wake. Patterns in the infaunal community composition appeared to be correlated with the size of the pit and by inference, the age of the pit. Large, deep pits were characterized by species considered early colonists of disturbed areas. Smaller, shallow depressions did not have elevated numbers of early colonists. Abundance of Ampelisca macrocephala, the dominant bottom organism and whale prey item, was depressed in all pits sampled. © 1983 Springer-Verlag., Cited By (since 1996):11, CODEN: OECOB, ,
Nerini, Oliver
Ice scour disturbance to benthic communities in the Canadian High Arctic,
Seabed scouring by ice is a large-scale disturbance to polar coasts. Grounding ice modifies seabed topography, reworks the sediment, and ploughs and crushes the seabed biota. The effects of ice scour on soft-sediment benthos were examined in Barrow Strait in High Arctic Canada. Due to the variability of ice keel depths in this area, the Barrow Strait coast was found to exhibit a gradient of ice scour disturbance to 30 m depth. The inshore shallows were highly scoured by the abundant shallow draft ice. Deeper water scours caused by icebergs and portions of ice shelves were less frequent. The benthos paralleled this disturbance gradient, with the inshore consisting of a disturbance-associated fauna. Four recently formed ice scours were studied at 3 locations. Despite differences in exposure to currents and water depth, all scours were dominated by the same disturbance-associated fauna and were distinctive from the benthos outside. Scavenging amphipods and gastropods consumed bivalves that were dislodged and damaged, while predatory amphipods and opportunistic polychaetes burrowed in the gouged and displaced clays. Our expectation was that the topography of the ice scours would select for different colonizing species. However, there was no evidence of preferential occupation of the raised berms by suspension feeders or of the troughs by deposit feeders. The species that dominated the 4 scours also dominated the less recently disturbed areas of the inshore, despite the fact that these areas were situated 300 to 400 m inshore and at shallower depth. The prevalence of species that associate with ice scours indicates that ice disturbance is an important factor that molds coastal benthic zonation at this Arctic location., Cited By (since 1996):65, CODEN: MESED, , , Downloaded from: www.int-res.com/articles/meps/166/m166p001.pdf (9 June 2014).,
Conlan, Lenihan, Kvitek, Oliver
EDTA chelation and zinc antagonism with cadmium in sediment,
Cited By (since 1996):15, Invertebrates, CODEN: MBIOA, The two species of infaunal amphipod crustaceans Rhepoxynius abronius (Phoxocephalidae) and Eohaustorius sencillus (Haustoriidae) are characteristic of nearshore sandy bottoms along the California (USA) coast, and are highly sensitive to moderate levels of heavy metals. In laboratory experiments, both zinc and the chelator EDTA increased the survival of amphipods in sediment containing otherwise lethal levels of cadmium (8.5 ug g-1), which are representative of moderately polluted environments. In simple choice experiments, amphipods prefer sediment with complexed cadmium. The behavioral and survival patterns of both species were similar in the experiments. EDTA prevented about 50% of the added cadmium from initially being incorporated into the sediment, and increased the rate of cadmium released from the sediment. These data illustrate the limitation of operational definitions of chemical analyses, since weak-acid (0.5 N HCl) leaches that were intended to provide an estimate of the "biologically available" metal concentrations extracted both toxic and EDTA-complexed cadmium species and did not account for their antagonistic interactions with zinc., ,
Oakden, Oliver, Flegal
Slattery (5) + -
Hammerstrom (4) + -
Kim (4) + -
Kvitek (4) + -
Conlan (3) + -
Lenihan (3) + -
Oakden (3) + -
Dayton (2) + -
Ranasinghe (2) + -
Weisberg (2) + -
Barber (1) + -
Barros (1) + -
Blanchet (1) + -
Cadien (1) + -
Carney (1) + -
Dauer (1) + -
Diener (1) + -