Search results

Title: Primitive synteny of vertebrate major histocompatibility complex class I and class II genes,
Description: Major histocompatibility complex (MHC) class I and class II molecules bind to and display peptidic antigens acquired from pathogens that are recognized by lymphocytes coordinating and executing adaptive immune responses. The two classes of MHC proteins have nearly identical tertiary structures and were derived from a common ancestor that probably existed not long before the emergence of the cartilaginous fish. Class I and class II genes are genetically linked in tetrapods but are not syntenic in teleost fish, a phylogenetic taxon derived from the oldest vertebrate ancestor examined to date. Cartilaginous fish (Sharks, skates, and rays) are in the oldest taxon of extant jawed vertebrates; we have carried out segregation analyses in two families of nurse sharks and one family of the banded houndshark that revealed a close linkage of class IIα and β genes both with each other and with the classical class I (class Ia) gene. These results strongly suggest that the primordial duplication giving rise to classical class I and class II occurred in cis, and the close linkage between these two classes of genes has been maintained for at least 460 million years in representatives of most vertebrate taxa., Cited By (since 1996):82, CODEN: PNASA, ,
Author: Ohta, Okamura, McKinney, Bartl, Hashimoto, Flajnik
Date: 2000-01-01T00:00:00Z

Title: Distribution density and relative abundance of benthic invertebrate megafauna from three sites at the base of the continental slope off central California as determined by camera sled and beam trawl,
Description: Distribution, density and relative abundance of benthic invertebrate megafauna at three sites at the base of the continental slope off central California were investigated by trawls and camera sleds over a two-year period. A total of 29 successful trawls returned a total of 133 species of invertebrates. The dominant taxa by number in the trawls were holothurians, ophiurans, pennatulids, and one species of sea star and one species of corallomorpharian. There was considerable variation in rank order of abundance of the dominant invertebrates among the three sites and within one of the sites between years. Thus the percent similarity among the three sites was also low. Three of the five most abundant species were burrowers and were not detected in the camera sleds. Comparisons of rank order of abundances between the camera sleds and the trawls was done for 18 taxa. Results indicated no significant differences between the two methods and a total percent similarity of 78.8%. Comparison of densities per 100 m2 between the two methods revealed that the densities estimated from the camera sleds were about 4 times those of the trawls. Reasons for this discrepancy are discussed., Cited By (since 1996):12, Invertebrates, CODEN: DSROE, ,
Author: Nybakken, Craig, Smith-Beasley, Moreno, Summers, Weetman
Date: 1998-01-01T00:00:00Z

Title: Temporal changes in deep-sea sponge populations are correlated to changes in surface climate and food supply
Description: Density and average size of two species of abyssal sponges were analyzed at Station M (~4100. m depth) over an 18-year time-series (1989-2006) using camera sled transects. Both sponge taxa share a similar plate-like morphology despite being within different families, and both showed similar variations in density and average body size over time, suggesting that the same factors may control the demographics of both species. Peaks in significant cross correlations between increases in particulate organic carbon flux and corresponding increases in sponge density occurred with a time lag of 13 months. Sponge density also fluctuated with changes in two climate indices: the NOI with a time lag of 18 months and NPGO with a time lag of 15 months. The results support previous suggestions that increased particulate organic carbon flux may induce recruitment or regeneration in deep-sea sponges. It is unknown whether the appearance of young individuals results from recruitment, regeneration, or both, but the population responses to seasonal and inter-annual changes in food supply demonstrate that sponge populations are dynamic and are capable of responding to inter-annual changes despite being sessile and presumably slow-growing. © 2012 Elsevier Ltd., Cited By (since 1996):4, Export Date: 24 September 2013, Source: Scopus, CODEN: DRORE
Author: Kahn, Ruhl, Smith
Date: 2012-01-01T00:00:00Z

Title: Effects of epiphyte load on optical properties and photosynthetic potential of the seagrasses Thalassia testudinum Banks ex König and Zostera marina L.,
Description: The biomass and optical properties of seagrass leaf epiphytes were measured to evaluate their potential impact on the photosynthetic performance of the seagrasses Thalassia testudinum Banks ex König (turtlegrass) and Zostera marina L. (eelgrass). Turtlegrass was obtained from oligotrophic waters near Lee Stocking Island, Bahamas; eelgrass was collected from a eutrophic environment in Monterey Bay, California. Leaf-epiphyte loads were characterized visually and quantified using measurements of their phospholipid biomass. Light absorption and reflectance of the intact epiphyte layer were determined spectrophotometrically. Turtlegrass epiphytes from the oligotrophic site absorbed a maximum of 36% of incident light in peak chlorophyll absorption bands, whereas higher epiphyte loads on eelgrass from the more eutrophic Monterey Bay absorbed 60% of incident light in peak chlorophyll absorption bands. The combination of intact epiphyte-leaf complexes and spectral measurements enabled us to construct a quantitative relationship between epiphyte biomass and light attenuation, and, by extension, between epiphyte biomass and seagrass photosynthesis. The model yielded a robust, positive relationship between epiphyte biomass and the absorption of photons in photosynthetically important wavelengths, and it generated a strong negative relationship between epiphyte biomass and spectral photosynthesis of their seagrass hosts. Furthermore, the calculations of photosynthesis highlighted the significant differences between PAR and spectral models of photosynthesis, illustrating that the spectral quality of the incident flux must be considered when evaluating the effects of epiphyte load on seagrass leaf photosynthesis. Verification of the model - using direct measurements of photosynthesis and a variety of epiphyte and macrophyte combinations from different locations - is warranted., Cited By (since 1996):34, Seaweeds, CODEN: LIOCA, ,
Author: Drake, Dobbs, Zimmerman
Date: 2003-01-01T00:00:00Z

Title: Influence of bottom currents on sediment texture and sea-floor morphology in the Argentine Basin,
Description: The relative bottom-current speed below 4000 m in the Argentine Basin was inferred from the regional pattern of mean particle size of the non-biogenic silt fraction of about 300 sea-floor samples. The pattern reveals a strong deep western boundary current (DWBC) entering the Argentine Basin from the Georgia Basin through a gap in the Falkland Fracture Zone. The DWBC turns W and flows as a contour current along the Falkland Escarpment and Argentine continental margin. At the southern end of the Rio Grande Rise, the DWBC is deflected to the E and SE where it flows along the lower flank of the Mid-Atlantic Ridge as a weak basin-wide return flow. Several smaller return-flow gyres in the southern and western basin are delineated in the regional pattern. The DWBC is strongest along the western margin of the Argentine Basin where 3.5 kHz echograms reveal very prolonged echoes with no sub-bottom reflectors. That reflector pattern is indicative of coarse turbidites, some of which have been winnowed to produce coarse-grained lag deposits under the axis of flow. In the interior of the basin, where bottom-current flow is weakest, sediment consists of clay and silt which is deposited in large migrating mud waves with wavelengths of 3-10 km and heights of up to 137 m (average 26 m). The mud waves consist of material swept into the basin by the DWBC and delivered to the basin margin by down-slope processes. Thus material is winnowed by the DWBC and deposited as a fine-grained chaff in abyssal antidunes which migrate to the centre of the basin and form thick drift deposits., , ,
Author: Ledbetter, Klaus
Date: 1987-01-01T00:00:00Z

Title: Lesions and behavior associated with forced copulation of juvenile Pacific harbor seals (Phoca vitulina richardsi) by southern sea otters (Enhydra lutris nereis),
Description: Nineteen occurrences of interspecific sexual behavior between male southern sea otters (Enhydra lutris nereis) and juvenile Pacific harbor seals (Phoca vitulina richardsi) were reported in Monterey Bay, California, between 2000 and 2002. At least three different male sea otters were observed harassing, dragging, guarding, and copulating with harbor seals for up to 7 d postmortem. Carcasses of 15 juvenile harbor seals were recovered, and seven were necropsied in detail by a veterinary pathologist. Necropsy findings from two female sea otters that were recovered dead from male sea otters exhibiting similar behavior are also presented to facilitate a comparison of lesions. The most frequent lesions included superficial skin lacerations; hemorrhage around the nose, eyes, flippers, and perineum; and traumatic corneal erosions or ulcers. The harbor seals sustained severe genital trauma, ranging from vaginal perforation to vagino-cervical transection, and colorectal perforations as a result of penile penetration. One harbor seal developed severe pneumoperitoneum subsequent to vaginal perforation, which was also observed in both female sea otters and has been reported as a postcoital lesion in humans. This study represents the first description of lesions resulting from forced copulation of harbor seals by sea otters and is also the first report of pneumoperitoneum secondary to forced copulation in a nonhuman animal. Possible explanations for this behavior are discussed in the context of sea otter biology and population demographics., Marine Mammals, Birds & Turtles, ,
Author: Harris, Oates, Staedler, Tinker, Jessup, Harvey, Miller
Date: 2010-01-01T00:00:00Z

Title: Utilizing fishermen knowledge and expertise: Keys to success for collaborative fisheries research
Description: Collaborative fisheries research provides a mechanism for integrating the unique knowledge, experience, and skills of fishermen and scientists. It is a joint intellectual endeavor that begins with the inception of a project and continues until its final stages, with each group having mutual investment in-and ownership of- the project. Collaborative fisheries research promotes communication and trust among fishermen, scientists, and managers and can provide much-needed scientifically valid data for fisheries management. It can enhance federal and state management data collection programs, which span broad sections of coastline, by increasing the ability to detect changes in local metapopulations that may be overfished or underutilized. We describe a methodology for conducting collaborative fisheries surveys and apply it to marine protected areas along the central California coast. During a series of workshops in 2006, attended by members of the fishing, academic, environmental, and management communities, protocols were established for conducting hook-and-line surveys collaboratively with commercial passenger fishing vessel captains and volunteer recreational anglers. The protocols have been implemented annually since 2007. This case study highlights the effectiveness of-and the essential steps in-developing our collaborative fisheries research and monitoring projects., Cited By (since 1996):1, Fish and Fisheries
Author: Yochum, Starr, Wendt
Date: 2011-01-01T00:00:00Z

Title: Benthic changes at McMurdo Station, Antarctica following local sewage treatment and regional iceberg-mediated productivity decline,
Description: 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, ,
Author: Conlan, Kim, Thurber, Hendrycks
Date: 2010-01-01T00:00:00Z

Title: Radiometric age confirmation and growth of a deep-water marine fish species: The bank rockfish, Sebastes rufus,
Description: Cited By (since 1996):4, , , ,
Author: Watters, Kline, Coale, Cailliet
Date: 2006-01-01T00:00:00Z

Title: Preface: Feeding ecology of elasmobranchs
Description: Elasmobranchs are apical predators in most marine communities where they occur, often playing a substantial role in the food web dynamics of those communities. However, despite their high trophic status they are often poorly studied compared to most commercially important teleosts. Furthermore, despite efforts towards ecosystem-based management, elasmobranchs are still often lumped into generic categories referred to as "shark" or "skate" unclassified, with limited effort to identify individual species. The role of elasmobranchs in ecosystems has never been more important to our understanding of marine ecology due to high levels of exploitation of many species. Similar to other high trophic level predators, many elasmobranchs have life-history characteristics that make them vulnerable to over-exploitation. Elasmobranch populations are now heavily targeted in many fisheries throughout the world. Increasing exploitation of this group is especially alarming because their feeding ecology is poorly studied and by extension their influence in shaping ecosystems. Given recent increased attention on elasmobranchs in the scientific literature, management and conservation circles, and the general news media, researchers over the past decade have begun to more closely examine the ecological role of this important taxon of fishes. Due to this increasing awareness, and the development of new and innovative methods and analytical techniques, it prompted us to organize an international symposium on the "Feeding Ecology of Elasmobranchs". The symposium was held on 10 July 2010, in conjunction with the 27 th annual meeting of the American Elasmobranch Society meetings in Providence, Rhode Island. © 2012 Springer Science+Business Media B.V.
Author: Ebert, McElroy, White
Date: 2012-01-01T00:00:00Z

Title: Walrus feeding disturbance: Scavenging habits and recolonization of the Bering Sea benthos,
Description: Walruses (Odobenus rosmarus Illiger) influenced the structure of macrobenthic assemblages in a variety of ways as they excavated their major bivalve prey from soft sediments. Benthic animals were attracted to discarded bivalve shells and they colonized pits and furrows made during prey excavation. Discarded shells contained soft tissues that were eaten by several invertebrate scavengers. The most abundant and widespread scavenger was the sea star, Asterias amurensis Lutken. Sea stars out-competed brittle stars (Amphiodia craterodmeta Clark) for fresh scavenging events. They also attacked brittle stars under shells in the laboratory, and thus may have obtained two meals from discarded shells by eating remnant tissue and by consuming animals that used the shell as a habitat. In nature, brittle stars were abundant under discarded shells. In experiments, brittle stars invaded shells with soft tissue in the absence of sea stars, but not in their presence. In other experiments, brittle stars were most abundant under shells with soft tissue, but were also attracted to shells without organic matter. Large brittle stars were more abundant under shells than in the surrounding bottom, and the reverse was true of small individuals. Bottom communities recovered gradually inside experimental feeding excavations, which were not invaded by large numbers of opportunistic infaunal or epifaunal invertebrates. This is in contrast to gray whale feeding excavations, which are colonized by a large number of opportunistic peracarid crustaceans. © 1985., Cited By (since 1996):32, CODEN: JEMBA, ,
Author: Oliver, Kvitek, Slattery
Date: 1985-01-01T00:00:00Z

Title: Living rhodolith beds in the Gulf of California and their significance for paleoenvironmental interpretation
Author: Foster, Riosmena-Rodriguez, Steller, Woelkerling, Johnson, Ledesma-Vazquez
Date: 1997-01-01T00:00:00Z

Title: Comparative age‑determination techniques for white sturgeon in California
Description: We compared growth patterns of clavicles, cleithra, opercles, medial nuchals, dorsal scutes, and pectoral fin ray sections from white sturgeon Acipenser transmontanus in California. The legibility and interpretability of growth patterns, ease of collection and processing, and relative precision of age estimates were evaluated for each structure with data collected on skeletal structures and morphometric measurements of 147 individuals ranging in size from 31 to 224 cm total length. Various methods were used to elucidate growth zones (thin-sectioning, oil and water clearing, staining, and X-ray radiography) to determine the most useful ageing technique for each structure. All calcified structures contained concentric growth zones that increased in number with the size of the fish and were interpreted as annual events. There was a direct linear relationship between size of the structures and size of the fish. Pectoral fin sections were the most practical ageing structure in terms of ease of collection, processing, legibility, and precision of interpretation. Age estimates from other structures resulted in poor precision between readers but relatively good intrareader precision. This suggests possible corroborative use with the development of better interpretive criteria and elucidation techniques. The von Bertalanffy, growth curve calculated from age estimates based on pectoral fin sections for all samples produced a growth model for white sturgeon that compared favorably with those from previous studies.
Author: Brennan, Cailliet
Date: 1989-01-01T00:00:00Z

Title: Premaxillary movements in cyprinodontiform fishes: An unusual protrusion mechanism facilitates "picking" prey capture,
Description: Premaxillary protrusion is hypothesized to confer a number of feeding advantages to teleost fishes; however, most proposed advantages relate to enhanced stealth or suction production during prey capture. Cyprinodontiformes exhibit an unusual form of premaxillary protrusion where the descending process of the premaxilla does not rotate anteriorly to occlude the sides of the open mouth during prey capture. Instead, the premaxilla is protruded such that it gives the impression of a beak during prey capture. We quantified premaxillary kinematics during feeding in four cyprinodontiform taxa and compared them with three percomorph taxa to identify any performance consequences of this protrusion mechanism. Individual prey capture events were recorded using digital high-speed video at 250-500 frames per second (n≥4 individuals, ≥4 strikes per individual). Species differed in the timing of movement and the maximum displacement of the premaxilla during the gape cycle and in the contribution of the premaxilla to jaw closing. Cyprinodontiform taxa produced less premaxillary protrusion than the percomorph taxa, and were consistently slower in the time to maximum gape. Further, it appears cyprinodontiforms can alter the contribution of the premaxilla to mouth closure on an event-specific basis. We were able to demonstrate that, within at least one species, this variability is associated with the location of the prey (bottom vs. water column). Cyprinodontiform upper jaw movements likely reflect increased dexterity associated with a foraging ecology where prey items are "picked" from a variety of locations: the bottom, water column, or surface. We postulate that dexterity requires slow, precisely controlled jaw movements; thus, may be traded off for some aspects of suction-feeding performance, such as protrusion distance and speed. © 2008 Elsevier GmbH. All rights reserved., Cited By (since 1996):8, ,
Author: Ferry-Graham, Gibb, Hernandez
Date: 2008-01-01T00:00:00Z

Title: Application of an ion-exchange separation technique and thermal ionization mass spectrometry to 226Ra for radiometric age determination of long-lived fishes,
Description: To improve the accuracy and precision of radiometric age determination using 210Pb: 226Ra disequilibria in otoliths of fishes, a technique was developed incorporating an ion-exchange procedure followed by isotope-dilution thermal ionization mass spectrometry (TIMS) to determine 226Ra. This technique counts ionized radium atoms directly; therefore, the uncertainty of the technique is superior to conventional radio-decay dependent techniques. Calcium and barium are major components of the otolith matrix that can interfere with TIMS analysis of radium. To remove these interferants, an ion-exchange separation procedure was developed. This procedure was tested by applying it to otolith samples from three fish species in three separate radiometric ageing studies. The resultant separations and TIMS determinations indicate that the procedure efficiently separates radium from calcium and barium. Measured 226Ra activities for each species were similar to previous radiometric ageing studies, with the exception of one sample. When results were compared with traditional 226Ra determination techniques, radon emanation and α-spectrometry, the separation procedure with isotope-dilution TIMS had significant advantages. Samples over three times smaller than attempted in other studies were processed with decreased uncertainty and processing time., Cited By (since 1996):30, Fish and Fisheries, CODEN: CJFSD, ,
Author: Andrews, Coale, Nowicki, Lundstrom, Palacz, Burton, Cailliet
Date: 1999-01-01T00:00:00Z

Title: Morphometric convergence and molecular divergence: The taxonomic status and evolutionary history of Gymnura crebripunctata and Gymnura marmorata in the eastern Pacific Ocean,
Description: To clarify the taxonomic status of Gymnura crebripunctata and Gymnura marmorata, the extent of morphological and nucleotide variation between these nominal species was examined using multivariate morphological and mitochondrial DNA comparisons of the same characters with congeneric species. Discriminant analysis of 21 morphometric variables from four species (G. crebripunctata, G. marmorata, Gymnura micrura and Gymnura poecilura) successfully distinguished species groupings. Classification success of eastern Pacific species improved further when specimens were grouped by species and sex. Discriminant analysis of size-corrected data generated species assignments that were consistently accurate in separating the two species (100% jackknifed assignment success). Nasal curtain length was identified as the character which contributed the most to discrimination of the two species. Sexual dimorphism was evident in several characters that have previously been relied upon to distinguish G. crebripunctata from G. marmorata. A previously unreported feature, the absence of a tail spine in G. crebripunctata, provides an improved method of field identification between these species. Phylogenetic and genetic distance analyses based on 698 base pairs of the mitochondrial cytochrome b gene indicate that G. crebripunctata and G. marmorata form highly divergent lineages, supporting their validity as distinct species. The closely related batoid Aetoplatea zonura clustered within the Gymnura clade, indicating that it may not represent a valid genus. Strong population structuring (overall Φ ST = 0.81,P < 0.01) was evident between G. marmorata from the Pacific coast of the Baja California peninsula and the Gulf of California, supporting the designation of distinct management units in these regions. © 2009 The Fisheries Society of the British Isles., Cited By (since 1996):6, CODEN: JFIBA, ,
Author: Smith, Bizzarro, Richards, Nielsen, Márquez-Flarías, Shivji
Date: 2009-01-01T00:00:00Z

Title: On quartet interactions in the California Current system
Description: Sea surface height (SSH) altimetry observations for 1992 to 2009 off California are used to show that observed quasi-zonal jets were likely driven by near-resonance interactions between different scales of the flow. Quartet (modulational) instability dominated and caused non-local transfer of energy from waves and eddies to biannual oscillations and quasi-zonal jets. Two types of quartets were identified: those composed of scales corresponding to (a) quasi-zonal jets, annual and semiannual Rossby waves and mesoscale eddies, and (b) biannual oscillations, semiannual Rossby waves and mesoscale eddies. The spectral centroid regularly shifted into the domain of low-order modes. However, the spectrum of SSHs does not demonstrate a power behavior. This says that the classical inverse cascade is absent. For a case with bottom friction, quartet instability required the existence of a certain level of dissipativity in the flow.
Date: 2014-01-01T00:00:00Z

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