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Published journal articles by MLML faculty, staff and students. Full text is included when copyright allows.


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Assessing mercury exposure and biomarkers in largemouth bass (Micropterus Salmoides) from a contaminated river system in California
Assessing mercury exposure and biomarkers in largemouth bass (Micropterus Salmoides) from a contaminated river system in California
We evaluated mercury (Hg) exposure and two biomarkers, metallothionein (MT) gene expression and histopathological alterations in a wild fish species, largemouth bass (Micropterus salmoides), collected from the Sacramento-San Joaquin Delta, CA, a region polluted with Hg from historic mining activities. Hg is highly toxic and can disrupt multiple physiological systems in vertebrate species, including the immune system. Total mercury (THg) concentration in muscle tissue ranged from 0.12 to 0.98 ppm (wet weight) and was not related to body condition (r 2 = 0.005, p = 0.555). Using linear regression analysis, we found a positive relationship between MT gene expression (as determined using quantitative polymerase chain reaction) and copper, zinc, manganese, aluminum, and nickel (decreased to one variable by way of principal component analysis) (r 2 = 0.379, p = 0.044), a negative relationship with selenium (r 2 = 0.487, p = 0.017), and a weak, negative relationship with THg concentrations (r 2 = 0.337, p = 0.061). Juvenile largemouth bass collected from Hg-contaminated areas displayed histopathological features of immunosuppression compared with those collected from less contaminated areas as evidenced by significantly lower macrophage density in kidney and liver tissue (p = 0.018 and 0.020, respectively), greater trematode density in liver tissue (p = 0.014), and a greater number of adult trematodes. Our results suggest that largemouth bass may be experiencing sublethal effects from chronic Hg exposure. Furthermore, our findings illustrate the utility of examining multiple sublethal markers of effect to assess the impacts of contaminant exposure on physiological function in wild species. © 2012 Springer Science+Business Media New York., Fish and Fisheries, CODEN: AECTC
Assessing the relationship between gulls Larus spp. and Pacific salmon in central California using radiotelemetry
Assessing the relationship between gulls Larus spp. and Pacific salmon in central California using radiotelemetry
Predation by marine birds has resulted in substantial losses to runs of Pacific salmon Oncorhynchus spp., in some cases necessitating management action. Recovery of PIT tages on a seabird breeding colony (Ano Nuevo Island) indicated that western gulls Larus occidentalis prey upon federally listed Coho Salmon Oncorhynchus kisutch and steelhead O. mykiss in central California. Whereas salmonid populations in central California have decreased in recent decades, the western gull population on Ano Nuevo Island has increased. We observed gulls Larus spp. within estuaries to document predation and used radiotelemetry to examine gull movement in relation to the availability of salmonids. During 2008 and 2009, observed predation events of out-migrating salmonids by gulls were rare; 21 events occurred during 338 h of observations at two estuaries. During the prehatch and chick-rearing phases of breeding, which coincided with migration of salmonids from fresh to salt water, 74% of the detections of radio-tagged western gulls occurred within 25 km of Ano Nuevo Island, suggesting that the relative susceptibility of predation by western gulls using Ano Nuevo Island decreased with distance from the island. Western gull presence at creek mouths was greatest during daylight hours (91% of detections), while juvenile salmonids were present predominantly at night (65% of detections). The greatest overlap between western gulls and salmonids occurred at dusk, and predation of out-migrating salmonids was likely opportunistic. Deterring gulls from creek mouths when overalp between predation and prey might otherwise occur may buffer out-migrating salmonids from predation. Our results will inform management strategies to most effectively reduce the impacts of gull predation on central California salmonids.
Assessment of MERIS reflectance data as processed with SeaDAS over the European seas
Assessment of MERIS reflectance data as processed with SeaDAS over the European seas
The uncertainties associated with MERIS remote sensing reflectance (R RS) data derived from the SeaWiFS Data Analysis System (SeaDAS) are assessed with field observations. In agreement with the strategy applied for other sensors, a vicarious calibration is conducted using in situ data from the Marine Optical BuoY offshore Hawaii, and leads to vicarious adjustment factors departing from 1 by 0.2% to 1.6%. The three field data sets used for validation have been collected at fixed stations in the northern Adriatic Sea and the Baltic Sea, and in a variety of European waters in the Baltic, Black, Mediterranean and North Seas. Excluding Baltic waters, the mean absolute relative difference |Psi;| between satellite and field data is 10-14% for the spectral interval 490-560 nm, 16-18% at 443 nm, and 24-26%at413 nm. In the Baltic Sea, the |Psi;| values are much higher for the blue bands characterized by low RRS amplitudes, but similar or lower at 560 and 665 nm. For the three validation sets, the root-mean-square differences decrease from approximately 0.0013 sr -1 at 413 nm to 0.0002 sr -1 at 665 nm, and are found similar or lower than those obtained for SeaWiFS or MODIS-Aqua. As derived from SeaDAS, the RRS records associated with these three missions thus provide a multi-mission data stream of consistent accuracy. © 2011 Optical Society of America., Cited By (since 1996):4, Oceanography
Assessment of demographic risk factors and management priorities
Assessment of demographic risk factors and management priorities
Predicting population-level effects from changes in demographic rates of different life stages is critical to prioritize conservation efforts. Demographic modeling and sensitivity analysis in particular, has become a standard tool to evaluate how management actions influence species' survival. Demographic analyses have resulted in the robust generalization that, for long-lived species with delayed reproduction, population growth rates will be most sensitive to changes in survivorship of older-aged individuals. Although useful in guiding management, this simple maxim may limit options for conservation by causing managers to overlook actions that, although possibly not the most effective in terms of increasing a population's growth rate in an ideal world, can nonetheless more feasibly and rapidly slow a population's decline. We examine the population-level benefits of increasing chick survival in a long-lived seabird, the Laysan albatross Phoebastria immutabilis. Specifically, we use a simple deterministic modeling approach to evaluate the impact of chick mortality (from ingestion of lead-based paint) on the population growth rate (λ) for Laysan albatross that breed on Sand Island, Midway Atoll (part of the Hawaiian Archipelago). We estimate that up to 7% of chicks on Sand Island fail to fledge as a result of lead poisoning, which will create a 16% reduction in the Laysan albatross population size (∼190 000 less birds) at 50 years into the future. We demonstrate how straightforward management actions that increase juvenile survivorship (e.g. removal of lead-based paint) can help slow population declines while efforts are underway to reduce politically and logistically challenging threats to adult survivorship (e.g. mortality from international fisheries bycatch). Our work exemplifies a situation where overgeneralizations about demography can stifle useful conservation actions and highlights the need to consider the population-level benefits from multiple management strategies. © 2009 The Authors. Journal compilation © 2009 The Zoological Society of London., Cited By (since 1996):9, Marine Mammals, Birds & Turtles
Assessment of errors associated with harbour seal (Phoca vitulina) faecal sampling
Assessment of errors associated with harbour seal (Phoca vitulina) faecal sampling
Six harbour seals, ages 4-8 years, were held as pairs in a 10 x 20 x 2 m tank filled with sea water, and on 60 occasions were fed a meal of a specific species of fish or cephalopod of known size. The tank was drained periodically, and harbour seal faeces were collected on a 0.5 mm sieve. Number and size of otoliths and beaks found in faeces were determined. Fifty-eight percent of 670 fish and 37% of 36 cephalopods fed to harbour seals were represented by their otoliths or beaks in faeces. Estimated number of prey consumed was determined from the greatest number of left or right otoliths or upper or lower beaks collected in faeces. Estimated length ofprey was determined from measurements of otoliths and beaks recovered in the tank and relationships of otolith and beak measurements to prey length. Estimated number of fish eaten was not significantly different among pairs of harbour seals, but was different among species of fishes. Only 24-35% of fish species with small otoliths were represented in faeces, whereas more robust otoliths from other species were less apt to be completely dissolved. Estimated length of fishes was significantly less than lengths of fishes fed to harbour seals in 39 (76.5%) of 51 trials. Cephalopod beaks were not affected by passage through the harbour seal digestive tract. Amount of otolith dissolution was not related to species of fish; estimated fish length was underestimated by an average 27.5%. Although some (7.4%) of the otoliths were collected within 100 h after the fish were ingested, more than 90% were recovered within 24 h after the fish was eaten. Correction factors were developed which will allow researchers to estimate more reliably number and size of fish and cephalopod prey eaten by harbour seals.
Assessment of length and age at maturity for California halibut (Paralichthys californicus), including a histologically-based description of the reproductive cycle
Assessment of length and age at maturity for California halibut (Paralichthys californicus), including a histologically-based description of the reproductive cycle
Estimates of length-And age-At-maturity for California halibut (Paralichthys californicus) have been reported for southern California, but not central California. To provide new estimates of length-And age-At-maturity for central California halibut, we macroscopically examined gonads from 635 fish caught between 2012 and 2014 and additionally examined ovaries histologically. We developed a detailed description of the reproductive phases and spawning states for California halibut, and assigned sex-specific length-And age-At-maturity to each individual. Males (n=333) ranged from 19.1 to 95.9 cm fork length (FL) and 1 to 16 yr of age and females (n=302) ranged from 18.6 to 111.0 cm FL and 1 to 19 yr of age. Males matured at younger ages and shorter lengths than females. The smallest mature male was measured at 25.7 cm (1 yr), 50% of males were mature by 27.0 cm (1.1 yr), and 100% were mature by 29.0 cm (3 yr). The smallest mature female was measured at 46.6 cm (2 yr), 50% of females were mature by 47.3 cm (2.6 yr), and 100% were mature by 51.3 cm (4 yr), according to histological criteria. Therefore, all California halibut examined were mature before reaching the commercial and recreational minimum legal size limit of 55.9 cm (22 in). When comparing central California maturity data with information from southern California, we found that central California halibut matured at larger sizes (both sexes) and older ages (females only) than southern California halibut, according to macroscopic criteria., Article
Assessment of radiometric dating for age validation of deep-water dogfish (Order: Squaliformes) finspines
Assessment of radiometric dating for age validation of deep-water dogfish (Order: Squaliformes) finspines
Vertebrae of most deep-water sharks are too poorly calcified to record visible growth bands and therefore are not useful for age determination. Most dogfish species (Order: Squaliformes) possess dorsal finspines and several recent studies have shown that these structures offer potential for age determination. Age validation should be central to any age determination study, yet to date no age and growth study of deep-water sharks has included a complete validation of age estimates. In this study we sought to age two deep-water dogfish species by analyzing 210Pb and 226Ra incorporated into the internal dentin of the finspines. These radiometric age estimates were compared with counts of internal growth bands observed in the finspines. A pilot study indicated that dorsal finspines of Centroselachus crepidater are too small and thus offer insufficient mass for the radiometric techniques employed in this study. For ageing larger finspines of Centrophorus squamosus, the lead-radium disequilibria method (ingrowth of 210Pb from 226Ra) was found to be inapplicable due to exogenous uptake of 210Pb in the finspine. Therefore, to approximate age, we measured the decay of 210Pb within the dentin material at the tip of the finspine (formed in utero), relative to the terminal material at the base of the finspine. Results with this method proved to be inconsistent and did not yield reliable age estimates. Hence the use of 210Pb and 226Ra for radiometric age determination and validation using dorsal finspines from these deep-water dogfishes was deemed unsuccessful. This outcome was likely due to violations of the consistent, life-long isotopic uptake assumption as well as the provision that the finspine must function as a closed system for these radioisotopes. Future improvements in analytical precision will allow for smaller samples to be analyzed, potentially yielding a better understanding of the fate of these radioisotopes within finspine dentin throughout the life of the shark. © 2013 Elsevier B.V., Fish and Fisheries
Assessment of sediment toxicity and chemical concentrations in the San Diego Bay region, California, USA
Assessment of sediment toxicity and chemical concentrations in the San Diego Bay region, California, USA
Sediment quality within San Diego Bay, Mission Bay, and the Tijuana River Estuary of California was investigated as part of an ongoing statewide monitoring effort (Bay Protection and Toxic Cleanup Program). Study objectives were to determine the incidence, spatial patterns, and spatial extent of toxicity in sediments and porewater; the concentration and distribution of potentially toxic anthropogenic chemicals; and the relationships between toxicity and chemical concentrations. Rhepoxynius abronius survival bioassays, grain size, and total organic carbon analyses were performed on 350 sediment samples. Strongylocentrotus purpuratus development bioassays were performed on 164 pore-water samples. Toxicity was demonstrated throughout the San Diego Bay region, with increased incidence and concordance occurring in areas of industrial and shipping activity. Trace metal and trace synthetic organic analyses were performed on 229 samples. Copper, zinc, mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlordane were found to exceed ERM (effects range median) or PEL (probable effects level) sediment quality guidelines and were considered the six major chemicals or chemical groups of concern. Statistical analysis of the relationships between amphipod toxicity, bulk phase sediment chemistry, and physical parameters demonstrated few significant linear relationships. Significant differences in chemical levels were found between toxic and nontoxic responses using multivariate and univariate statistics. Potential sources of anthropogenic chemicals were discussed., Cited By (since 1996):36, Rocks and Cores, CODEN: ETOCD
Assessment of the dorsal fin spine for chimaeroid (Holocephali: Chimaeriformes) age estimation
Assessment of the dorsal fin spine for chimaeroid (Holocephali: Chimaeriformes) age estimation
Previous attempts to age chimaeroids have not rigorously tested assumptions of dorsal fin spine growth dynamics. Here, novel imaging and data-analysis techniques revealed that the dorsal fin spine of the spotted ratfish Hydrolagus colliei is an unreliable structure for age estimation. Variation among individuals in the relationship between spine width and distance from the spine tip indicated that the technique of transverse sectioning may impart imprecision and bias to age estimates. The number of growth-band pairs observed by light microscopy in the inner dentine layer was not a good predictor of body size. Mineral density gradients, indicative of growth zones, were absent in the dorsal fin spine of H. colliei, decreasing the likelihood that the bands observed by light microscopy represent a record of growth with consistent periodicity. These results indicate that the hypothesis of aseasonal growth remains plausible and it should not be assumed that chimaeroid age is quantifiable by standard techniques. © 2009 The Fisheries Society of the British Isles., Cited By (since 1996):2, Fish and Fisheries, CODEN: JFIBA
At-sea mortality of seabirds based on beachcast and offshore surveys
At-sea mortality of seabirds based on beachcast and offshore surveys
Although seabird population biology is relatively well studied, little data exists on mortality at-sea. Beached bird surveys are used to identify patterns of seabird mortality, but resulting patterns are difficult to interpret without corresponding data on at-sea density. We examined seabird mortality relative to at-sea density in Monterey Bay, California over 10 yr by integrating data from monthly beachcast seabird and offshore seabird censuses. Beachcast seabird numbers were relatively constant (mean 2.82 ± 0.31 seabirds km -1) throughout the year. At-sea seabird density (mean 148.9 ± 16.12 seabirds km-2) peaked in the summer upwelling period and was least in the winter Davidson period. A principal components analysis of seasonal climatic, prey availability, and anthropogenic variables for Monterey Bay derived 3 significant principal components (PCs) (explaining 70% of variance) characterized by storm activity and low prey availability (PC1), river discharge and krill abundance (PC2), and oiling (PC3). These principal components were used in detailed analyses of the 2 most abundant seabird species and indicate that sooty shearwater Puffinus griseus relative mortality is greatest during decreased productivity and increased storm activity. While relative mortality of common murres Uria aalge cannot be explained by the derived principal components, relative mortality increased in late winter when prey availability decreased concurrent with the annual increase in reproductive stress. Beachcast seabird data is difficult to interpret in isolation; however, when linked to at-sea densities of seabirds, it becomes a powerful tool to examine the relative impacts of oceanography and direct human perturbations on seabird demography. © Inter-Research 2009., Cited By (since 1996):1, Marine Mammals, Birds & Turtles, CODEN: MESED
Authigenic carbonate formation at hydrocarbon seeps in continental margin sediments
Authigenic carbonate formation at hydrocarbon seeps in continental margin sediments
Authigenic carbonates from five continental margin locations, the Eel River Basin, Monterey Bay, Santa Barbara Basin, the Sea of Okhotsk, and the North Sea, exhibit a wide range of mineralogical and stable isotopic compositions. These precipitates include aragonite, low- and high-Mg calcite, and dolomite. The carbon isotopic composition of carbonates varies widely, ranging from -60‰ to +26‰, indicating complex carbon sources that include 13C-depleted microbial and thermogenic methane and residual, 13C-enriched, bicarbonate. A similarly large variability of δ18O values (-5.5‰ to +8.9‰) demonstrates the geochemical complexity of these sites, with some samples pointing toward an 18O-enriched oxygen source possibly related to advection of 18O-enriched formation water or to the decomposition of gas hydrate. Samples depleted in 18O are consistent with formation deeper in the sediment or mixing of pore fluids with meteoric water during carbonate precipitation. A wide range of isotopic and mineralogical variation in authigenic carbonate composition within individual study areas but common trends across multiple geographic areas suggest that these parameters alone are not indicative for certain tectonic or geochemical settings. Rather, the observed variations probably reflect local controls on the flux of carbon and other reduced ions, such as faults, fluid conduits, the presence or absence of gas hydrate in the sediment, and the temporal evolution of the local carbon reservoir. Areas with seafloor carbonates that indicate formation at greater depth below the sediment-water interface must have undergone uplift and erosion in the past or are still being uplifted. Consequently, the occurrence of carbonate slabs on the seafloor in areas of active hydrocarbon seepage is commonly an indicator of exhumation following carbonate precipitation in the shallow subsurface. Therefore, careful petrographic and geochemical analyses are critical components necessary for the correct interpretation of processes related to hydrocarbon seepage in continental margin environments and elsewhere. © 2007 Elsevier Ltd. All rights reserved., Cited By (since 1996):46, Rocks and Cores, CODEN: DSROE
Bacterial chemolithotrophy in the ocean is associated with sinking particles
Bacterial chemolithotrophy in the ocean is associated with sinking particles
The oceanic carbon cycle has traditionally been viewed as a reversible, one step reduction-oxidation reaction (CO 2CH 2O). Principle pathways were thought to involve eukaryotic photoautotrophy and oxygen-dependent bacterial respiration, respectively. However, prokaryotic (cyanobacterial) photoautotrophy is now well documented and has even been proposed as a major carbon pathway 1-6. In a previous study of the mesopelagic zone in the North Pacific Ocean 7, the observed downward fluxes of organic carbon, nitrogen, ATP and RNA suggested production in situ of new particulate organic carbon at 700-900 m. Here we present evidence that this is indeed the case and that it is mediated by bacterial chemolithotrophy. Energy for this process may be in part provided by detrital NH + 4 derived from the downward flux of large particles. © 1984 Nature Publishing Group., Cited By (since 1996):33, Oceanography
Bacterial production and the sinking flux of particulate organic matter in the subarctic Pacific
Bacterial production and the sinking flux of particulate organic matter in the subarctic Pacific
We measured bacterial production and estimated the carbon consumption by bacteria in the mesopelagic zone (80-600 m) in the subarctic Pacific during May and August. Bacterial production was measured by leucine and thymidine incorporation. The two methods gave similar results. Bacterial production in the euphotic zone accounted for about 13% of primary production and in the whole water column for 20% (0-600 m). To bracket bacterial carbon consumption we made a lowest and highest estimate of bacterial production. The lowest estimate assumes zero isotope dilution for converting 14C-leucine incorporation rates into bacterial production and a 50% growth efficiency. In the mesopelagic zone, this estimate implies that bacterial account for 52 and 41% of the POC sinking flux as measured by sediment traps in May and August, respectively. The highest estimate, assuming two-fold isotope dilution of 14C-leucine and a 30% growth efficiency, yields bacterial carbon consumption values of 172 and 137% of the POC downward flux in both months. This indicates that bacteria are important, if not the major consumers of organic matter in the mesopelagic zone of the subarctic Pacific. © 1992., Cited By (since 1996):27, Oceanography
Barometer Rising: The Cartagena Protocol on Biosafety as a Model for Holistic International Regulation of Ocean Fertilization Projects and Other Forms of Geoengineering
Barometer Rising: The Cartagena Protocol on Biosafety as a Model for Holistic International Regulation of Ocean Fertilization Projects and Other Forms of Geoengineering
"Give me a half a tanker of iron and I'll give you the next ice age." JohnMartin, the architect of what came to be known as the iron hypothesis, oncemade this statement jokingly in a lecture he gave at theWoods Hole Oceanographic Institution.2 Shortly after his death, in October of 1993, the research vessel Columbus Iselin departedMiami to head toward the Galapagos Islands where his colleagues conducted the first ever large-scale iron fertilization experiments.3While the linemay have been intended as hyperbole, Martin could have no idea how controversial his theorywould become amidst a growing international debate about global climate change. Earth's average
Bathydorus laniger and Docosaccus maculatus (Lyssacinosida: Hexactinellida)
Bathydorus laniger and Docosaccus maculatus (Lyssacinosida: Hexactinellida)
Two new species of glass sponge were discovered from the abyssal plain 200 km west of the coast of California (Station M). The sponges have similar gross morphology-an unusual plate-like form with basalia stilting the body above soft abyssal sediments. Bathydorus laniger sp. n. differs from its congeners by the presence of dermal and atrial stauractins; it is also supported by smooth hypodermal pentactins and hypoatrial hexactins. Microscleres include oxyhexasters and oxyhemihexasters. Docosaccus maculatus sp. n. contains large hexactins (>1 cm), characteristic of the genus. Megas-cleres include dermal hexactins, atrial pentactins, and choanosomal hexactins and diactins. Microscleres include oxy-tipped hemihexasters and floricomes. Several features serve to differentiate this species from its only known congener. Copyright © 2013 Magnolia Press., Invertebrates, doi: 10.11646/zootaxa.3646.4.4
Beach use, internesting movement, and migration of leatherback turtles, Dermochelys coriacea, nesting on the North Coast of Papua New Guinea
Beach use, internesting movement, and migration of leatherback turtles, Dermochelys coriacea, nesting on the North Coast of Papua New Guinea
Internesting and migratory movements of female leatherback turtles (Dermochelys coriacea) from Kamiali Wildlife Management Area were tracked by satellite telemetry during the 2001-2002 and 2002-2003 nesting seasons, and an aerial survey of nearly 2800 km of the north Papua New Guinea coastline and New Britain Island was conducted during January 2004. Nesting occurred during November-March at the Kamiali Wildlife Management Area monitoring beach with peak activity during December-January. Telemetry results indicated that nesting females used Huon Gulf waters adjacent to the nesting beach and renested inside and outside the protected area within the Kamiali Wildlife Management Area. After nesting, the turtles migrated over deep waters in a southeastern direction to high latitude waters of the South Pacific Ocean. © 2007 Chelonian Research Foundation., Cited By (since 1996):18, Marine Mammals, Birds & Turtles
Beached birds and physical forcing in the California Current System
Beached birds and physical forcing in the California Current System
Seabirds have often been proposed as environmental indicators. Beached bird data may provide an additional data source and such data is efficacious because it can reliably be collected by volunteers. In addition to anthropogenic factors, such as oil spills, changes in the ocean-atmosphere can affect carcass beaching rate in 3 non-exclusive ways: (1) direct mortality following storms, (2) mortality via bottom-up food web processes, and (3) increase in carcass delivery due to shifts in surface water movement. We used data from 3 volunteer-based beached bird data sets collected within the California Current System (CCS) to (1) examine the level of response to anomalous ocean conditions in 2005 and (2) explore the degree to which long-term beaching patterns could be explained by one or more of our proposed mechanisms. In 2005, anomalous die-offs of Cassin's auklet Ptychorhamphus aleuticus and the rhinoceros auklet Cerorhinca monocerata occurred in the winter in Monterey. By spring, anomalous die-offs of Brandt's cormorant Phalacrocorax pencillatus and the common murre Uria aalge occurred throughout the CCS. Over the longer term, increases in beaching were associated with changes in the timing and intensity of upwelling and, secondarily, with zonal winds aloft - a potential proxy of shifts in pelagic community composition. These results suggest that a bottom-up food web mechanism best explains seabird beaching, at least in the spring. Correlations of local measures of storminess to seabird beaching rates were weak to non-existent. Correlations were much stronger at the California site (8 yr) and weaker to non-existent at the Oregon site (26 yr). Collectively, these data suggest that relationships between ocean physics and beached bird response may be site specific and/or may reflect choices live birds make vis-à-vis non-breeding distribution. © Inter-Research 2007., Cited By (since 1996):9, Marine Mammals, Birds & Turtles, CODEN: MESED
Behavior of bowhead whales, Balaena mysticetus, summering in the Beaufort sea: A description
Behavior of bowhead whales, Balaena mysticetus, summering in the Beaufort sea: A description
In 1980, whales alternated periods of socializing with periods of feeding in several different ways: near the bottom, in the water column, with some socializing and skim feeding. In 1982, almost all activity appared to be feeding in the water column. In 1980, most whales studied were in water only 10-40m deep. In 1981 they were farther from shore and in >20m depth, and in 1982 long (10-30 min) dives were common in depths of 40-600m. Variability in distribution and behavior presumably was related to availability of prey. During near-surface skim feeding, whales often associated in V-shaped or echelon formations, with up to 14 animals staggered behind and to the side of each other, all moving in the same direction at the same speed, with mouths wide open. Such coordinated movement may increase the efficiency of feeding on concentrations of small invertebrates.-from Authors, Cited By (since 1996):16, Marine Mammals, Birds & Turtles
Behavior of gray whales summering near St. Lawrence Island, Bering Sea
Behavior of gray whales summering near St. Lawrence Island, Bering Sea
Most Eschrichtius robustus behavior involved apparent benthic feeding. There was little socializing by whales in July, but more in late September. Percent of time at the surface was about 21% in July and 23% in September. There were fewer blows per surfacing, shorter surface times, and shorter dive times when whales were not feeding than when they were feeding. Intervals between successive blows were longer in nonfeeding whales, but number of blows per minute did not differ between feeding and nonfeeding whales. Number of blows per surfacing and duration of surfacing increased with increasing water depth (from <20-80m). Dive duration did not change appreciably with depth in July, but did so in September. Blow rates by feeding whales increased in deeper water, indicating the need for whales to respire more as depth of dives increased. Time of day affected surfacing-dive respiration characteristics differently in different months. Whales fed more from 1800-2100 local Bering Sea time than at other times of day. During an average surfacing, feeding whales moved approx 50m; during a dive, net horizontal movements were 90-100m. Speed averaged 2km/h and was twice as fast at the surface (3.4km/h) compared with net underwater speed (1.7km/h)., Cited By (since 1996):12, Marine Mammals, Birds & Turtles
Behavior, movements, and apparent survival of rehabilitated and free-ranging harbor seal pups
Behavior, movements, and apparent survival of rehabilitated and free-ranging harbor seal pups
Cited By (since 1996):17, Marine Mammals, Birds & Turtles Harbor Seals
Behavioral ecology of killer whales (Orcinus orca) in the Pacific Northwest
Behavioral ecology of killer whales (Orcinus orca) in the Pacific Northwest
Resident killer whales fed more in areas of high relief subsurface topography along salmon migratory routes, and may use these geographic features to increase feeding efficiency. Transient whales fed in shallow protected areas around concentrations of their prey, harbor seals Phoca vitulina. Whales traveled across deep, featureless areas in moving from one feeding area to another. Whales rested depending on the previous sequence of behaviors and played in open water areas or adjacent to feeding areas. Location of food resources and habitats suitable for prey capture appears to be the prime determining factor in the behavioral ecology of these whales, most likely representing cultural mechanisms that have been learned through trial and error experiences leading to successful foraging strategies., Cited By (since 1996):34, Marine Mammals, Birds & Turtles
Behavioral influences on the physiological responses of Cancer gracilis, the graceful crab, during hyposaline exposure
Behavioral influences on the physiological responses of Cancer gracilis, the graceful crab, during hyposaline exposure
The relationship between the behavioral and physiological responses to hyposaline exposure was investigated in Cancer gracilis, the graceful crab. The status of C. gracilis as an osmoconformer was confirmed. Survival decreased with salinity: the LT50 in 50% seawater (a practical salinity of 16, or 16‰) was 31.5 ± 22.7 h and in 25% seawater (a salinity of 8) was 8.0 ± 0.7 h. When exposed to a salinity gradient, most crabs moved towards the highest salinity. However, in the salinity range of 55% to 65% seawater, they became quiescent. This "closure response" was also evident at low salinities: the mouthparts were tightly closed and animals remained motionless for 2 to 2.5 h. During closure, crabs were able to maintain the salinity of water within the branchial chambers at a level that was about 30% higher than that of the surrounding medium. The closure response was closely linked to a short-term decrease in oxygen uptake. During closure, oxygen within the branchial chamber was rapidly depleted, with oxygen uptake returning to pretreatment levels upon the resumption of activity. In addition to the short-term decrease in oxygen uptake, there was a longer-term bradycardia, which may serve to further reduce diffusive ion loss across the gills. By exhibiting a closure response during acute hyposaline exposure and an avoidance reaction during prolonged or severe hyposaline exposure, C. gracilis is able to use behavior to exploit areas prone to frequent episodes of low salinity. © 2007 Marine Biological Laboratory., Cited By (since 1996):7, Invertebrates, CODEN: BIBUB
Behaviour of bowhead whales Balaena mysticetus summering in the Beaufort Sea: Reactions to industrial activities
Behaviour of bowhead whales Balaena mysticetus summering in the Beaufort Sea: Reactions to industrial activities
Behaviour near actual and simulated activities associated with offshore oil exploration was compared with 'presumably undisturbed' behaviour. Underwater noise was monitored. Reactions to an approaching fixedwing aircraft were frequent if it was at ≤ 305 m above sea level, infrequent at 457 m, and not detected at 610 m. When boats closed to within 1-4 km, surface/dive cycles became shorter and the whales swam rapidly away. Fleeing ceased when the vessel was a few kilometres beyond the whales, but scattering persisted longer. Bowheads did not move away from seismic vessels ≥ 6 km away, but subtle effects on behaviour sometimes were suspected. We found bowheads as close as 4 km from drillships and < 1 km from a dredge, but drilling noise playback experiments provided evidence of an avoidance reaction. In general, bowheads showed. © 1985., Cited By (since 1996):24, Marine Mammals, Birds & Turtles, CODEN: BICOB
Benthic changes at McMurdo Station, Antarctica following local sewage treatment and regional iceberg-mediated productivity decline
Benthic changes at McMurdo Station, Antarctica following local sewage treatment and regional iceberg-mediated productivity decline
McMurdo Station, the largest research station in Antarctica, ceased on-site garbage dumping in 1988 and initiated sewage treatment in 2003. In 2003-2004 its sea-ice regime was altered by the massive B-15A and C-19 iceberg groundings in the Ross Sea, approximately 100 km distant. Here we follow macrofaunal response to these changes relative to a baseline sampled since 1988. In the submarine garbage dump, surface contaminants levels have declined but associated macrofaunal recolonization is not yet evident. Although sewage-associated macrofauna were still abundant around the outfall nearly 2 yr after initiation of treatment, small changes downcurrent as far as 434 m from the outfall suggest some community recovery. Widespread community changes in 2003-2004, not seen in the decade previously, suggests that the benthos collectively responded to major changes in sea-ice regime and phytoplankton production caused by the iceberg groundings. Crown Copyright © 2009., Cited By (since 1996):9, Invertebrates, Antarctica, CODEN: MPNBA

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