Search results

Title: Short term and long-term effects of toxicants on larval red abalone, Haliotis rufescens,
Description: Experiments were conducted to correlate a short-term 48-hour aquatic toxicity test endpoint of abnormal larval shell development with other, more clearly adverse effects. In similar experiments conducted with two different toxicants, zinc sulfate and Bleached Kraft Mill Effluent (BKME), red abalone (Haliotis rufescens) embryos were simultaneously added to identical dilution series and incubated for three different exposure periods: 48-hours, 48-hours followed by an 8-day recovery period, or a 10-day continuous exposure. Abnormal larval shell development was assessed in the 48-hour tests, and inhibition of metamorphosis was assessed in the exposure-recovery (ER) and long-term (LT)exposures. For the zinc experiments, the median effective concentration (ECso) values for the 48-hour exposure, the ER, and the LT exposures were 40, 32, and 29 ~g/L zinc, respectively. For the BKME experiments, the ECso values were 1.00%, 0.78%, and 0.67% effluent, respectively. Results indicate that toxicant concentrations causing abnormal larval shell development also inhibit metamorphosis, and that larvae exposed to toxicant concentrations which inhibit larval shell development do not recover to metamorphose when transferred to clean seawater. None of the successfully metamorphosed post larvae had deformed larval shells, indicating that shell deformity precludes survival past the planktonic stage. To determine if toxicant exposure delays metamorphosis, a 15-day continuous and exposure-recovery EKME experiment was conducted. No significant difference in post-larval shell lengths of successfully metamorphosed abalone could be attributed to either toxicant concentration or duration of exposure. Results indicate that exposure to a toxicant acts to inhibit rather than delay the initiation of metamorphosis., Invertebrates, ,
Author: Conroy

Title: Genetic diversity in native and introduced populations of the amethyst gem clam Gemma gemma (Totten, 1834) from the U.S. east and west coasts
Description: Reduced genetic diversity due to founder effects often is expected for invasive populations. The present study examined two nuclear gene regions and one mitochondrial gene to evaluate the origins and genetic diversity of Gemma gemma, a 'stow-away' that was introduced to California more than 100 years ago with the importation of the Eastern oyster, Crassostrea virginica, from the United States' Atlantic coast. A previous investigation involving mitochondrial DNA cytochrome-c-oxidase subunit I sequences reported no significant difference in haplotype diversity between the native and introduced populations; however, estimates of allelic (or haplotypic) variability are insensitive to losses of rare alleles that may accompany founder events and population bottlenecks. Estimates of allele richness and the distribution of rare alleles provide more sensitive indicators of such events. The present investigation of introduced and potential source populations identified lower allele richness and number of singleton alleles in California samples. Atlantic coast Gemma exhibit a sharp phylogeographic transition between northeastern (New York through New England) and mid-Atlantic (southern New Jersey through Virginia) subpopulations, which appear latitudinally inverted for the California Gemma populations. These genetic results, and information from the transportation history of the Eastern oyster, help to clarify processes involved in the introduction of this invasive species. © 2014 The Author(s)., Invertebrates
Author: Zhang, Geller, Vrijenhoek
Date: 2014-01-01T00:00:00Z

Title: Species richness and interacting factors control invasibility of a marine community
Description: Anthropogenic vectors have moved marine species around the world leading to increased invasions and expanded species' ranges. The biotic resistance hypothesis of Elton (in The ecology of invasions by animals and plants, 1958) predicts that more diverse communities should have greater resistance to invasions, but experiments have been equivocal. We hypothesized that species richness interacts with other factors to determine experimental outcomes. We manipulated species richness, species composition (native and introduced) and availability of bare space in invertebrate assemblages in a marina in Monterey, CA. Increased species richness significantly interacted with both initial cover of native species and of all organisms to collectively decrease recruitment. Although native species decreased recruitment, introduced species had a similar effect, and we concluded that biotic resistance is conferred by total species richness. We suggest that contradictory conclusions in previous studies about the role of diversity in regulating invasions reflect uncontrolled variables in those experiments that modified the effect of species richness. Our results suggest that patches of low diversity and abundance may facilitate invasions, and that such patches, once colonized by non-indigenous species, can resist both native and non-indigenous species recruitment., Invertebrates, Ecology
Author: Marraffini, Geller
Date: 2015-01-01T00:00:00Z

Title: The geographic variation of silver in the black turban snail, Tegula funebralis,
Description: The geographic variation of silver concentrations in the black turban snail, Tegula funebralis, along the California coastline indicates an anthropogenic influence. Relatively elevated levels of the metal occur in organisms adjacent to major wastewater outfalls compared to those from less populated areas. This parallels the distributions of silver concentrations in other molluscs within the area. It, therefore, substantiates the proposal that the pattern is primarily due to external factors, such as wastewater discharges, rather than intraspecific differences among the samples. The geographic variation of silver concentrations in the black turban snail, Tegula funebralis, along the California coastline indicates an anthropogenic influence. Relatively elevated levels of the metal occur in organisms adjacent to major wastewater outfalls compared to those from less populated areas. This parallels the distributions of silver concentrations in other molluscs within the area. It, therefore, substantiates the proposal that the pattern is primarily due to external factors, such as wastewater discharges, rather than intraspecific differences among the samples. Refs., Invertebrates, Ecology, ,
Author: Flegal
Date: 1980-01-01T00:00:00Z

Title: Pasiphaea magna
Description: Invertebrate zoology

Title: Puncturella sp.
Description: Collected by Invertebrate class

Title: The level of agreement among experts applying best professional judgment to assess the condition of benthic infaunal communities,
Description: 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, ,
Author: Weisberg, Thompson, Ranasinghe, Montagne, Cadien, Dauer, Diener, Oliver, Reish, Velarde, Word
Date: 2008-01-01T00:00:00Z

Title: Comparison of seastar (Asteroidea) fauna across island groups of the Scotia Arc,
Description: The Antarctic shelf fauna is isolated from other continental shelf faunas both physically by distance, and oceanographically by the Antarctic circumpolar current (ACC). To elucidate the relative importance of these two isolating mechanisms, we used the seastar fauna of the south-Atlantic sub-Antarctic islands to address the hypothesis that the ACC is dominant in controlling the distribution pattern of Antarctic fauna. We expected that seastar faunas from islands on the high latitude side of the ACC would show more similarities to each other than to faunas from islands on the low latitude side. The alternative isolation by distance model predicted that the island furthest from others would have the most unique fauna. For shelf-depth (<500 m) Asteroidea of the Scotia Arc region, assemblages were more similar between islands on each side of the ACC barrier than islands that were closer together, and this pattern was caused by differences in abundance of a few ubiquitous species. © 2006 Springer-Verlag., Cited By (since 1996):3 Invertebrates, ,
Author: Kim, Thurber
Date: 2007-01-01T00:00:00Z

Title: The feeding habits of Pleurobranchaea californica: MacFarland, 1966 (Opisthobranchia Notaspidea) in Monterey Bay, California,
Description: The natural diet of Pleurobranchaea californica was studied in Monterey Bay, California. Specimens were collected from 29 January to 9 November 1992, at depths of 30-100 m using an otter trawl and an interfacial trawl. Three hundred fifty-six individuals were collected and ranged in size from 0.01-411 g with most of the individuals weighing between 1.0 and 50 g. The gut contents were examined and 16 different taxa were identified. Thirty-three percent of the guts were empty. Many animals had sediment in their guts, which was presumed to be a result of their ingesting or attempting to ingest prey. Pleurobranchaea californica was found to be a euryphagic predator with pronounced cannibalism. Individual Index of Relative Importance values showed that opisthobranchs made up the largest portion of the diet. The opisthobranchs in the diet included Pleurobranchaea californica (as prey), Armina californica, and Aglaja sp. The diets were similar for specimens of P. californica collected at all depths, but did change depending upon the season in which the animals were collected., Cited By (since 1996):4, Invertebrates, ,
Author: Battle, Nybakken
Date: 1998-01-01T00:00:00Z

Title: A new species of eastern Pacific Fissidentalium (Mollusca: Scaphopoda),
Description: Fissidentalium erosum sp. nov. is described morphometrically from specimens collected from deep water off California. It is distinguished from F. megathyris primarily on the basis of soft-body-part proportions and radular characteristics. Shell differences are slight; the ventral aperture of F. erosum is approximately circular, whereas in F. megathyris the aperture is distinctly wider than high. The posterior portion of Fissidentalium erosum shells is often eroded, in contrast to the uneroded condition of most F. megathyris shells collected at the same station., Cited By (since 1996):3, , , Invertebrates
Author: Shimek, Moreno
Date: 1996-01-01T00:00:00Z

Title: Shell-burrowing barnacles,
Description: Acrothoracican cirripeds burrow in a variety of shelly materials dating back to the Carboniferous. The burrow is usually less than 5 mm in depth, with a smaller, tapered, slit-shaped aperture.Chemical action is proposed for initial penetration, and as an aid to the abrasive action of the teeth on the mantle and along the lateral bar. The burrowed shell is usually dead, and varies markedly in hardness. © 1969 by the American Society of Zoologists., Cited By (since 1996):8, Invertebrates, ,
Author: Tomlixsox
Date: 1969-01-01T00:00:00Z

Title: Effect of sample area and sieve size on benthic macrofaunal community condition assessments in california enclosed bays and estuaries,
Description: 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, ,
Author: Hammerstrom, Ranasinghe, Weisberg, Oliver, Fairey, Slattery, Oakdeny
Date: 2012-01-01T00:00:00Z

Title: Did the molecules of adaptive immunity evolve from the innate immune system?
Description: The antigen receptors on cells of innate immune systems recognize broadly expressed markers on non-host cells while the receptors on lymphocytes of the adaptive immune system display a higher level of specificity. Adaptive immunity, with its exquisite specificity and immunological memory, has only been found in the jawed vertebrates, which also display innate immunity. Jawless fishes and invertebrates only have innate immunity. In the adaptive immune response, T and B-lymphocytes detect foreign agents or antigens using T cell receptors (TCR) or immunoglobulins (Ig), respectively. While Ig can bind free intact antigens, TCR only binds processed antigenic fragments that are presented on molecules encoded in the major histocompatibility complex (MHC). MHC molecules display variation through allelic polymorphism. A diverse repertoire of Ig and TCR molecules is generated by gene rearrangement and junctional diversity, processes carried out by the recombinase activating gene (RAG) products and terminal deoxynucleotidyl transferase (TdT). Thus, the molecules that define adaptive immunity are TCR, Ig, MHC molecules, RAG products and TdT. No direct predecessors of these molecules have been found in the jawless fishes or invertebrates. In contrast, the complement cascade can be activated by either adaptive or innate immune systems and contains examples of molecules that gradually evolved from non-immune functions to being part of the innate and then adaptive immune system. In this paper we examine the molecules of the adaptive immune system and speculate on the existence of direct predecessors that were part of innate immunity., Cited By (since 1996):6, Invertebrates
Author: Bartl, Baish, Weissman, Diaz
Date: 2003-01-01T00:00:00Z

Title: A worldwide review of the food of nudibranch mollusks. Part II. The suborder dendronotacea,
Description: The prey items of 108 species representing all 10 families of the suborder Dendronotacea are presented in shortened form from the much larger electronic database accessible on the Web., Cited By (since 1996):9, , , Invertebrates
Author: McDonald, Nybakken
Date: 1999-01-01T00:00:00Z

Title: Bryoliths (Bryozoa) in the Gulf of California,
Description: Populations of Diaperoforma californica (d'Orbigny) bryoliths were discovered in rhodolith beds, a sand habitat, and on a cobble bottom in the Gulf of California, Mexico, the first known observation of a modern free-living cyclostome bryozoan in the Northern Hemisphere. Densities ranged from a mean of 9.2 to 22.6 individuals/0.06 m 2. Bryoliths from the deepest site were irregularly shaped and had the highest variation in shape; those from shallow sites were spheroidal. Water motion and bioturbation move the bryoliths and may determine their morphology. Schizomavella robertsonae (Soule, Soule & Chaney) bryoliths also occurred occasionally in one rhodolith bed sampled. Fossilized bryolith specimens of the cyclostome Diaperoforma californica (d'Orbigny) were found in a Pleistocene deposit near modern habitats. © 2006 by University of Hawai'i Press All rights reserved., Cited By (since 1996):6, Invertebrates, ,
Author: James, Foster, O'Sullivan
Date: 2006-01-01T00:00:00Z

Title: Characterization of microsatellite loci in the European green crab (Carcinus maenas),
Description: Carcinus maenas (Decapoda: Portunidae) has proven a highly successful invasive marine species whose potential economic and ecological impacts are of great concern worldwide. Here, we characterize 14 polymorphic microsatellite loci in C. maenas and its sister species Carcinus aestuarii. These markers will prove useful for fine-scale genetic analyses of native and introduced populations, for assessment of the sources and routes of invasion and for evaluation of post-invasion population dynamics. © 2006 Blackwell Publishing Ltd., Cited By (since 1996):14, Invertebrates, CODEN: MENOC, ,
Author: Tepolt, Bagley, Geller, Blum
Date: 2006-01-01T00:00:00Z

Title: Sedimentation in McMurdo Sound, Antarctica: A disturbance mechanism for benthic invertebrates,
Description: A slumping event that occurred on permanent transect lines from 12- to 30- m depth located at Arrival Heights, McMurdo Sound, Antarctica in 1993, provided an opportunity to examine the effects of sediment-mediated disturbance on the benthic invertebrate fauna. The disturbance had a particularly significant impact on the soft coral Alcyonium paessleri, which resulted in 84% colony mortality downslope from the slump site compared to an average annual mortality rate of 14% on control transects. In contrast, anchor ice at the same site accounted for removal of 5% of the population in 1992. Laboratory experiments with A. paessleri colonies under conditions of periodic sediment resuspension indicate that the soft corals are susceptible to this form of disturbance. Our observations suggest they are capable of shedding fine silt in the laboratory, which might ex-plain the presence of A. paessleri in soft-sediment sites around McMurdo Sound. However, scarring by larger gravel in laboratory assays was slow to heal and may account for much of the colony mortality we observed. Several invertebrate-barren rocky benthic regions in McMurdo Sound were suggestive of historical slumping events. Given the removal of the smaller grain size sediments from these areas - a typically slow process it appears these communities are slow to recover. The long-term effects of sedimentation on the benthic communities are unknown, but the impact on A. paessleri, one of the most common and fastest growing species, suggests this disturbance mechanism could lead to significant restructuring of these communities., Cited By (since 1996):13, Invertebrates, CODEN: POBID, ,
Author: Slattery, Bockus
Date: 1997-01-01T00:00:00Z

Title: A review of apparent 20th century changes in the presence of mussels (Mytilus trossulus) and macroalgae in Arctic, Alaska, and of historical and paleontological evidence used to relate mollusc distributions to climate change
Description: Live mussels attached to fresh laminarioid brown algae, all fastened to clusters of pebbles and small cobbles, were repeatedly cast ashore by autumn storms at Barrow, Alaska, in the 1990s. Specimens of Laminaria saccharina and L. solidungula shorten by 100 km a 500 km gap (Peard Bay to Stefansson Sound) between previously known concentrations of these kelp species. For the genus Mytilus, a 1 600 km gap in fully documented locations existed between Kivalina in the southern Chukchi Sea and the Mackenzie River delta. Barrow specimens were identified using a mitochondrial DNA marker as M. trossulus, an identity consistent with dispersal from the Pacific-Bering side of the Arctic. Live mussels and macroalgae were neither washed up by storms nor collected by active biological sampling during extensive benthic surveys at Barrow in 1948-50. We cannot interpret the current presence of these bivalves and macrophytes as Arctic range extensions due to warming, similar to those manifested by the tree line in terrestrial systems and by Pacific salmon in marine environments. Supplemental information and critical evaluation of survey strategies and rationales indicate that changes in sea temperatures are an unlikely cause. Alternative explanations focus on past seafloor disturbances, dispersal from marine or estuarine refugia, and effects of predators on colonists. This review suggests refining some interpretations of environmental change that are based on the extensive resource of Cenozoic fossils of Arctic molluscs., Cited By (since 1996):16, CODEN: ATICA, Invertebrates
Author: Feder, Norton, Geller
Date: 2003-01-01T00:00:00Z

Title: Broad-scale factors influencing the biodiversity of coastal benthic communities of the Ross Sea,
Description: Early ecological research in McMurdo Sound revealed local spatial gradients in community structure associated with variations in anchor ice disturbance, fast ice and snow cover, and the effects of predators. Research contrasting the east and west sides of McMurdo Sound has shown major differences in benthic communities, which have been attributed to oceanographic influences on the advection of water-column productivity and the frequency of fast ice break-out. Despite these regional and local differences, coastal benthic communities in McMurdo Sound show a high level of stability, and contain a variety of large and potentially very long-lived species. In Terra Nova Bay, about half way along the Victoria Land Coast of the western Ross Sea, the coastal benthic communities provide some insightful contrasts with those in McMurdo Sound. For example, the abundance and depth distribution of dominant species such as Sterechinus neumayeri and Adamussium colbecki are markedly different from McMurdo Sound. In both locations communities dominated by large sponges are most prolific in regions that are free from iceberg disturbance of the seabed. A recent assessment of northern Victoria Land coastal benthic communities, in conjunction with multibeam imagery of the seafloor, further highlights the importance of iceberg disturbance in structuring Antarctic benthic communities. A comparative synthesis of these coastal ecological studies enables us to generate hypotheses concerning the relative importance of different environmental drivers in structuring benthic communities. Overlain on the regular latitudinal shifts in physical factors such as light regime, are regional fluctuations that are controlled by atmospheric and oceanographic circulation patterns and coastal topography/bathymetry. Change in diversity along the western coast of the Ross Sea is predicted to be influenced by three main factors (1) ice disturbance (e.g., via anchor ice and advection of supercooled water or icebergs), (2) photosynthetically available radiation (affected by ice and snow cover and water clarity), (3) the locations of polynyas and advection of planktonic production and larvae. Interactions between these factors are expected to result in non-linear changes along the latitudinal gradient. While predictions generated from these hypotheses remain to be rigorously tested, they provide indications of how benthic communities may respond to changes in production, disturbance and the stability of coastal sea ice. © 2006 Elsevier Ltd. All rights reserved., Cited By (since 1996):28, Invertebrates, CODEN: DSROE, ,
Author: Thrush, Dayton, Cattaneo-Vietti, Chiantore, Cummings, Andrew, Hawes, Kim, Kvitek, Schwarz
Date: 2006-01-01T00:00:00Z

Title: Black pools of death: Hypoxic, brine-filled ice gouge depressions become lethal traps for benthic organisms in a shallow Arctic embayment,
Description: Numerous small (9 ± 7 m2, mean ± SD) depressions filled with dark water were found covering 14% of the shallows (<10 m) sea floor of Resolute Bay, NWT, Canada, on July 28, 1995. The water in these black pools was hypoxic, warmer, and more saline and sulfide rich than surrounding bottom water. These pools also contained high numbers of dead epibenthic species, including: shrimps, amphipods, mysids, bivalves, gastropods, sea cucumbers, and fishes. Infaunal abundance and biomass, as well as benthic chlorophyll concentrations, were significantly lower inside the black pools than in the surrounding sediments. The pools persisted until the first strong wind to occur after annual sea-ice break-up. A year (July 1996), sulfide-rich black saline pools were again found in the same depressions as well as in new depressions formed by grounding ice during the previous summer. We hypothesize that the pools form annually, as the sea ice expels dense brine, which sinks and collects in previously formed ice gouge depressions on the shallow of Resolute Bay. Benthic respiration would be sufficient to drive the stratified water in the pools to anoxia in the absence of currents and turnover, resulting in microbial production of highly toxic sulfides. Once established, the pools persist as lethal traps for benthic and demersal organisms until dispersed by wind or waves after breakup of the annual ice cover., Cited By (since 1996):27, Invertebrates, CODEN: MESED, ,
Author: Kvitek, Conlan, Iampietro
Date: 1998-01-01T00:00:00Z

Title: Biologic and geologic characteristics of cold seeps in Monterey Bay, California,
Description: Cold seep communities discovered at three previously unknown sites between 600 and 1000 m in Monterey Bay, California, are dominated by chemoautotrophic bacteria (Beggiatoa sp.) and vesicomyid clams (5 sp.). Other seep-associated fauna included galatheid crabs (Munidopsis sp.), vestimentiferan worms (Lamellibrachia barhami?), solemyid clams (Solemya sp.), columbellid snails (Mitrella permodesta, Amphissa sp.), and pyropeltid limpets (Pyropelta sp.). More than 50 species of regional (i.e. non-seep) benthic fauna were also observed at seeps. Ratios of stable carbon isotopes (δ13C) in clam tissues near -36‰ indicate sulfur-oxidizing chemosynthetic production, rather than non-seep food sources, as their principal trophic pathway. The 'Mt Crushmore' cold seep site is located in a vertically faulted and fractured region of the Pliocene Purisima Formation along the walls of Monterey Canyon (~635 m), where seepage appears to derive from sulfide-rich fluids within the Purisima Formation. The 'Clam Field' cold seep site, also in Monterey Canyon (~900 m) is located near outcrops in the hydrocarbon-bearing Monterey Formation. Chemosynthetic communities were also found at an accretionary-like prism on the continental slope near 1000 m depth (Clam Flat site). Fluid flow at the 'Clam Flat' site is thought to represent dewatering of accretionary sediments by tectonic compression, or hydrocarbon formation at depth, or both. Sulfide levels in pore waters were low at Mt Crushmore (ca 0.2 mM), and high at the two deeper sites (ca 7.011.0 mM). Methane was not detected at the Mt Crushmore site, but ranged from 0.06 to 2.0 mM at the other sites., Cited By (since 1996):108, Invertebrates, CODEN: DRORE, ,
Author: Barry, Greene, Orange, Baxter, Robison, Kochevar, Nybakken, Reed, McHugh
Date: 1996-01-01T00:00:00Z

Title: Brittle star distribution patterns and population densities on the continental slope off central California (Echinodermata: Ophiuroidea),
Description: The ophiuroid communities on the continental slope off central California were examined using box cores and trawls. Box cores were taken between 550 and 3085 m at sites southwest of the Farallon Islands, and otter and beam trawls were used below 2300 m at three sites between the Farallon Islands and Point Sur. Eighteen ophiuroid species from six families were identified. Eighty percent of the individuals collected with box cores belonged to two species, Ophiura leptoctenia and Ophiacantha normani, which were dominant between 1000 and 2000 m. The largest ophiuroid faunal break occurred at around 2000 m and was associated with elevated dissolved oxygen levels, decreasing sediment grain size, and increasing sediment organic content. A comparison of box-core and trawl data from below 2300 m showed that box cores undersampled the ophiuroid community on the continental slope, missing almost 50% of the species collected by trawls within the same area, whereas trawls underestimated ophiuroid densities, reporting on average 243 times fewer ophiuroids per m2 than did box cores. There was a change in species relative abundance patterns between sampling locations. Ophiuroids exhibited patchy spatial distribution patterns on both a small scale of around 0.1 m2 and a large scale on the order of 100-1000 s of square meters. (C) 2000 Elsevier Science Ltd., Cited By (since 1996):14, Invertebrates, CODEN: DSROE, ,
Author: Summers, Nybakken
Date: 2000-01-01T00:00:00Z

Title: Long-term monitoring of krill recruitment and abundance indices in the Elephant Island area (Antarctic Peninsula),
Description: Krill distribution and density are reviewed for the Elephant Island area with regard to the representativeness of the study area (60°-62°30′S and 53°-57°30′W) for proportional recruit and density indices. Proportional recruitment indices were re-calculated applying the delta distribution approach introduced by de la Mare (1994a). The high interannual variability of krill recruitment is confirmed by the present analysis. Results are compared for one- and two-year-old krill (R1 and R2 respectively). Statistically significant fluctuations in krill density over the period 1977 to 1994 are also confirmed by this study using randomisation tests on an analysis of variance., Cited By (since 1996):33, Antarctica, Invertebrates, ,
Author: Siegel, De La Mare, Loeb
Date: 1997-01-01T00:00:00Z

Title: Diet, movement, and covering behavior of the sea urchin Toxopneustes roseus in rhodolith beds in the Gulf of California, México,
Description: The density, diet, movement, and covering behavior of Toxopneustes roseus (Agassiz) were investigated in rhodolith beds in the Gulf of California. Densities varied from a mean of 0.4 to 1.8/20 m2 with most urchins occurring in aggregations. Spatial patterns of urchins varied with depth, with greatest abundance at intermediate depths (7.5-9.4 m) in the middle of the rhodolith bed. Urchins ate rhodoliths and nongeniculate coralline algal crusts almost exclusively, despite the availability of other algae. The mean amounts ingested were 3.87 and 7.96 g carbonate/individual per day. Even when food was abundant, animals were highly mobile, moving an average of 6.6-11.7 cm/h depending on site and time of day. Diel movement may be a behavioral adaptation to avoid surge, which is greatest during the day. Covering behavior may also be related to surge, as the ratio of covering material:body weight and the percent cover of material held were highest at the site with the most surge. While an urchin consumed rhodoliths, its movement spread the grazing impact over large areas. Bioturbation resulting from urchin feeding, movement, and covering activity probably benefits the rhodoliths by turning them, which maintains rhodolith integrity, prevents fouling, and contributes to bed persistence., Cited By (since 1996):38, Invertebrates, CODEN: MBIOA, ,
Author: James
Date: 2000-01-01T00:00:00Z

Title: European green crabs (Carcinus maenas) in the Northeastern Pacific,
Description: Aim The European green crab (Carcinus maenas) expanded dramatically after its introduction to the west coast of North America, spreading over 1000 km in < 10 years. We use samples of Carcinus maenas collected over time and space to investigate the genetic patterns underlying the species' initial establishment and spread, and discuss our findings in the context of the species' life history characteristics and demography. Location The central west coast of North America, encompassing California, Oregon, and Washington (USA) and British Columbia (Canada). Methods We collected 1040 total samples from 21 sites representing the major episodes of population establishment and expansion along the west coast of North America. Microsatellite markers were used to assess genetic diversity and structure at different time points in the species' spread, to investigate connectivity between embayments and to estimate both short-term effective population sizes and the number of original founders. Assignment testing was performed to determine the likely source of the introduction. Results Carcinus maenas in western North America likely derived from a single introduction of a small number of founders to San Francisco Bay, CA from the east coast of North America. Throughout its western North American range, the species experiences periodic migration between embayments, resulting in a minor loss of genetic diversity in more recently established populations versus the populations in the area of initial establishment. Main conclusions Low genetic diversity has not precluded the ability of C. maenas to successfully establish and spread on the west coast of North America. An efficient oceanographic transport mechanism combined with highly conducive life history traits are likely the major drivers of C. maenas spread. Evidence for a single introduction underscores the potential utility of early detection and eradication of high-risk invasive species. © 2009 Blackwell Publishing Ltd., Cited By (since 1996):9, Invertebrates, CODEN: DIDIF, ,
Author: Tepolt, Darling, Bagley, Geller, Blum, Grosholz
Date: 2009-01-01T00:00:00Z

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