Articles

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


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Bomb radiocarbon dating of the endangered white abalone (Haliotis sorenseni)
Bomb radiocarbon dating of the endangered white abalone (Haliotis sorenseni)
Understanding basic life-history characteristics of white abalone (Haliotis sorenseni), such as estimated lifespan, is critical to making informed decisions regarding the recovery of this endangered species. All predictive modelling tools used to forecast the status and health of populations following restoration activities depend on a validated estimate of adult lifespan. Of the seven Haliotis species in California, white abalone is considered to have the highest extinction risk and was the first marine invertebrate listed as an endangered species under the Federal Endangered Species Act (ESA). Lifespan was previously estimated from observations of early growth; however, no study has generated ages for the largest white abalone. To address questions of age and growth, bomb radiocarbon (Δ14C) dating was used on shells from large white abalone. Measured bomb Δ14C levels were compared to regional Δ14C reference records to provide estimates of age, growth and lifespan. Bomb radiocarbon dating indicated that growth was variable among individuals, with a maximum estimated age of 27 years. The findings presented here provide support for previous age and growth estimates and an estimated lifespan near 30 years. These age data support the perception of a critical need for restoring the remnant aging and potentially senescent population. © CSIRO 2013., Fish & Fisheries, CODEN: AJMFA
Bottom-current pathways in the Argentine Basin revealed by mean silt particle size
Bottom-current pathways in the Argentine Basin revealed by mean silt particle size
Regional circulation patterns in the deep sea are very difficult to determine because of time constraints on the acquisition of large physical-oceanographic data sets from abyssal depths; in addition, the large number of long-term (≳1 yr) current-meter arrays needed to delineate bottom-current pathways are extremely costly. An alternative method for inferring benthic flow patterns, described here, is to map the mean size of the silt fraction of sediment on the sea floor. Because of the availability of a large number of core samples in the Argentine Basin, the particle-size approach provides a useful method for determining bottom-current pathways in that deep basin. © 1986 Nature Publishing Group., Cited By (since 1996):16, Rocks and Cores
Bottom-current speed in the Vema Channel recorded by particle size of sediment fine-fraction
Bottom-current speed in the Vema Channel recorded by particle size of sediment fine-fraction
The particle-size distribution of the carbonate-free silt fraction was determined in forty-two core-top samples from the east flank of the Vema Channel in order to allow comparison of the mean particle size with near-bottom current speed based on nearby CTD and current-meter observations. The silt mean particle size fluctuates insignificantly between 1450-3950 m but coarsens markedly below 4000 m under Antarctic-source bottom currents. The top of the zone of coarse sizes approximates the top of Lower Circumpolar Water (LCPW) at ∼4000 m; the steep gradient to coarsest sizes in the axis of the channel marks the transition to Antarctic Bottom Water (AABW). The vertical profile of mean particle size on the east flank correlates in general respects with the vertical velocity gradient in the channel axis although the core sites on the east flank are as far as ∼200 miles from the current-meter arrays. Nevertheless, this relationship is used to infer that the non-carbonate particle sizes deposited on the east flank of the channel may be an indication of bottom-current speed and, therefore, the mean size is used to reconstruct profiles of mean current speed for three time slices (18, 120 and 140 ka B.P.). During glacial isotopic stages 2 and 6 the particle sizes deposited on the east flank of the channel are characterized by finer sizes at nearly all depths and the zone of coarse sizes corresponding to LCPW and AABW deepens. During interglacial isotopic stage 5e, the particlesize profile is very similar to the modern profile; however, LCPW and AABW appear to be deeper than at present. The finer particle sizes deposited at nearly all depths during glacial periods indicates that the velocity of deep circulation in the Atlantic was reduced in response to the ice ages. Deep circulation during isotopic stage 5e closely resembled modern circulation; however, AABW production rates may have been less that at present. © 1984., Cited By (since 1996):16, Rocks and Cores, CODEN: MAGEA
Boundary-interior exchange: Reviewing the idea that internal-wave mixing enhances lateral dispersal near continental margins
Boundary-interior exchange: Reviewing the idea that internal-wave mixing enhances lateral dispersal near continental margins
Near-boundary mixing affects the dispersal of seawater constituents and may have important consequences for ecological and geological processes since continental boundaries are a fundamental source of lithogenic sediments, nutrients, iron and carbon. This paper examines the idea that gravitational collapse after near-boundary vertical mixing events leads to enhanced dispersal in the horizontal (along-isopycnal) direction. Dye studies from the continental shelf and laboratory investigations of intrusions generated by internal-wave breaking suggest that this is a viable mechanism for offshore dispersal of boundary-layer fluid. However, there have been few attempts to examine this process in the ocean or to quantify it in a form amenable to parameterization. Here this process is considered primarily for continental slopes and conditions of relatively uniform stratification, rather than for shelves where the boundary can intersect a front or seasonal thermocline. This paper reviews a selection of studies examining this concept in the laboratory and ocean, and reviews studies linking internal-wave reflection and mixing to the offshore dispersal of suspended sediment from continental margins. © 2006 Elsevier Ltd. All rights reserved., Cited By (since 1996):27, Oceanography, CODEN: DSROE
Breaking up and getting together: Evolution of symbiosis and cloning by fission in sea anemones (genus Anthopleura)
Breaking up and getting together: Evolution of symbiosis and cloning by fission in sea anemones (genus Anthopleura)
Clonal growth and symbiosis with photosynthetic zooxanthellae typify many genera of marine organisms, suggesting that these traits are usually conserved. However, some, such as Anthopleura, a genus of sea anemones, contain members lacking one or both of these traits. The evolutionary origins of these traits in 13 species of Anthopleura were inferred from a molecular phylogeny derived from 395 bp of the mitochondrial 16S rRNA gene and 410 bp of the mitochondrial cytochrome oxidase subunit III gene. Sequences from these genes were combined and analyzed by maximum-parsimony, maximum-likelihood, and neighbor-joining methods. Best trees from each method indicated a minimum of four changes in growth mode and that symbiosis with zooxanthellae has arisen independently in eastern and western Pacific species. Alternative trees in which species sharing growth modes or the symbiotic condition were constrained to be monophyletic were significantly worse than best trees. Although clade composition was mostly consistent with geographic sympatry, A. artemisia from California was included in the western Pacific clade. Likewise, A. midori from Japan was not placed in a clade containing only other Asian congeners. The history of Anthopleura includes repeated shifts between clonality and solitariness, repeated attainment of symbiosis with zooxanthellae, and intercontinental dispersal., Cited By (since 1996):31, Invertebrates, CODEN: EVOLA
Breaking with tradition: Redefining measures for diet description with a case study of the Aleutian skate Bathyraja aleutica (Gilbert 1896)
Breaking with tradition: Redefining measures for diet description with a case study of the Aleutian skate Bathyraja aleutica (Gilbert 1896)
Characterization of fish diets from stomach content analysis commonly involves the calculation of multiple relative measures of prey quantity (%N,%W,%FO), and their combination in the standardized Index of Relative Importance (%IRI). Examining the underlying structure of dietary data matrices reveals interdependencies among diet measures, and obviates the advantageous use of underused prey-specific measures to diet characterization. With these interdependencies clearly realized as formal mathematical expressions, we proceed to isolate algebraically, the inherent bias in %IRI, and provide a correction for it by substituting traditional measures with prey-specific measures. The resultant new index, the Prey-Specific Index of Relative Importance (%PSIRI), is introduced and recommended to replace %IRI for its demonstrated more balanced treatment of the relative measures of prey quantity, and less erroneous behavior across taxonomic levels of identified prey. As a case study, %PSIRI was used to examine the diet of the Aleutian skate Bathyraja aleutica from specimens collected from three ecoregions of the northern Gulf of Alaska (GOA) continental shelf during June-September 2005-2007. Aleutian skate were found to primarily consume the commonly abundant benthic crustaceans, northern pink shrimp Pandalus eous and Tanner crab Chionoecetes bairdi, and secondarily consume various teleost fishes. Multivariate variance partitioning by Redundancy Analysis revealed spatially driven differences in the diet to be as influential as skate size, sex, and depth of capture. Euphausiids and other mid-water prey in the diet were strongly associated with the Shelikof Strait region during 2007 that may be explained by atypical marine climate conditions during that year. © 2011 Springer Science+Business Media B.V., Cited By (since 1996):2, Fish and Fisheries, CODEN: EBFID
Brittle star distribution patterns and population densities on the continental slope off central California (Echinodermata: Ophiuroidea)
Brittle star distribution patterns and population densities on the continental slope off central California (Echinodermata: Ophiuroidea)
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
Broad-scale factors influencing the biodiversity of coastal benthic communities of the Ross Sea
Broad-scale factors influencing the biodiversity of coastal benthic communities of the Ross Sea
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
Bryoliths (Bryozoa) in the Gulf of California
Bryoliths (Bryozoa) in the Gulf of California
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
Burrow environment and coelomic fluid characteristics of the echiuran worm Urechis caupo from populations at three sites in northern California
Burrow environment and coelomic fluid characteristics of the echiuran worm Urechis caupo from populations at three sites in northern California
The burrow microhabitat and physiology of the echiuran worm Urechis caupo at a high-density site (Elkhorn Slough, California, USA), were investigated from 1987 to 1990 to determine physical and chemical conditions, worm density and distribution, and coelomic fluid characteristics such as heme composition, pO2, pH, and coelomocyte volume. During tidal exposure, worm burrows at this site exhibited, on average, 52% air-saturated water, 11μM burrow-water sulfide, 85 μg/mg wet weight sediment sulfide, and salinity and osmolalities similar to those of seawater. These conditions are compared to those of another California site, Bodega Bay, which had slightly lower oxygen concentrations, but higher water and sediment-sulfide levels. A more limited comparison to a third site, Princeton Harbor, California, is included. Worms from Bodega Bay, the higher sulfide site, had greater concentrations of hematin, a non-globin heme compound contained in the coelomocytes, and exhibited a greater tolerance to sulfide in the laboratory. These data are consistent with the hypothesis that hematin is a sulfide-detoxifying agent that may enhance survival of U. caupo in the sulfide-rich mudflat environment. © 1992 Springer-Verlag., Cited By (since 1996):22, Invertebrates, CODEN: MBIOA
Burrowing behavior, habitat, and functional morphology of the Pacific sand lance (Ammodytes personatus).
Burrowing behavior, habitat, and functional morphology of the Pacific sand lance (Ammodytes personatus).
The Pacific sand lance (Ammodytes personatus) is a small, elongate forage fish that spends much of its life buried in the seafloor. We determined that the Pacific sand lance can burrow in a wide variety of sediments from silt to gravel, but it prefers coarse sand (0.50-1.00 mm grain size). In the absence of coarse sand, the Pacific sand lance chooses larger grain sizes over smaller ones. These preferences are independent of light or the compaction of sediment, and therefore indicate that visual cues and ease of entry are not primary means of choosing burial substrate. Instead, we speculate that the Pacific sand lance is morphologically adapted for rapid mobility in coarse sand and that coarse sand has enough interstitial spaces to enable respiration during protracted immersion. As an obligate burrower in specific sediments, the Pacific sand lance is a good candidate for habitat-based management. Substrate maps of 3 fishing grounds in southeast Alaska where the Pacific sand lance is abundant and where habitat-based management is practiced were used to create potential habitat maps. Different geologic histories have resulted in variable amounts of preferred (sand-gravel), suitable (sand mixed with silt, cobble-boulder, or rock outcrop), and unsuitable (mud, pebble-boulder) habitat for this species among regions. [ABSTRACT FROM AUTHOR], Article
Bythaelurus bachi n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the southwestern Indian Ocean, with a review of Bythaelurus species and a key to their identification.
Bythaelurus bachi n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the southwestern Indian Ocean, with a review of Bythaelurus species and a key to their identification.
A new deep-water catshark, Bythaelurus bachi, is described based on 44 specimens caught on the southern Madagascar Ridge in the southwestern Indian Ocean. The new species is the only stout-bodied Bythaelurus with oral papillae in the region and is distinguished from all congeners by the plain beige to light gray-brown coloration, high diversity in dermal denticle morphology, and presence of composite oral papillae. Despite resemblance in body shape, Bythaelurus bachi n. sp. is distinguished from its closest congener, B. naylori Ebert & Clerkin, 2015, by the presence of numerous large, partially composite papillae on the tongue and roof of the mouth (vs. papillae lacking), plain light coloration (vs. medium to dark brown ground color, light fin edges and a distinctly dark dusky-colored snout), only slightly enlarged dermal denticles on the anterior upper caudal-fin margin (vs. dermal denticles distinctly enlarged), a higher diversity in dermal denticle morphology in general, and smaller maximum size and size at maturity. The distinction of both species is also supported by molecular results. The new species differs from all other congeners in the western Indian Ocean in the stout body shape of large specimens, coloration, larger size, as well as several morphometrics, including larger claspers, longer eyes and dorsal fins, and shorter pelvic—anal and pelvic—caudal spaces. The genus is reviewed, a key to its species given.
Cadmium flux in Los Angeles/Long Beach harbours and at sites along the California continental margin
Cadmium flux in Los Angeles/Long Beach harbours and at sites along the California continental margin
Fluxes of dissolved cadmium were measured in situ using benthic flux chambers at stations in Los Angeles/Long Beach harbour and at sites on the California continental margin. Cadmium fluxes ranged from -0.212 to 0.118 μmol m-2 d-1 indicating that Cd flux may either be into or out of sediments. Correlations between Cd flux and carbon oxidation rate and between carbon oxidation rate and sulfate reduction indicate that anaerobic microbial degradation was the major process controlling both the sign and the magnitude of cadmium fluxes at stations in Los Angeles and Long Beach harbours. A simple box model based on sediment fluxes and water column concentrations indicates cadmium has a residence time of 47 days within the Los Angeles/Long Beach harbour system, similar to the hydraulic residence time. Sedimentary flux is, therefore, sufficient to account for water column cadmium concentration in inner harbour areas, suggesting that the sediments are the dominant source and sink of cadmium in these areas of the harbour. Comparison of the cadmium: phosphate ratio for the Los Angeles/Long Beach harbour water column with those reported for the northeast Pacific suggests that distributions of Cd in the study area were elevated over expected values but appear to be dominated by natural physical and biogeochemical processes. © 2001 Academic Press., Cited By (since 1996):9, Oceanography, CODEN: ECSSD
Cadmium in plankton: Elevated concentrations of Baja California
Cadmium in plankton: Elevated concentrations of Baja California
135 Plankton samples were collected in the northwest Pacific Ocean and analyzed for their cadmium content. Concentrations were generally low (2 to 5 micrograms of cadmium per gram, dry wt) in all samples, except for the plankton collected off Baja California, where high values (10 to 20 parts per million) were consistently found on 2 cruises., Cited By (since 1996):24, Oceanography, CODEN: SCIEA
Calcitonin-like immunoreactivity in serum and tissues of the Bonnethead Shark, Sphyrna tiburo
Calcitonin-like immunoreactivity in serum and tissues of the Bonnethead Shark, Sphyrna tiburo
Calcitonin is a 32-amino acid peptide hormone that is best known for its actions in maintaining skeletal integrity and calcium homeostasis in mammals. Calcitonin also appears to function in regulating certain aspects of animal reproduction, but the nature of this role remains unclear, particularly in nonmammalian vertebrates. The present study investigated the relationship between calcitonin and reproduction in the bonnethead shark (Sphyrna tiburo), a well-studied member of the oldest living vertebrate group (i.e. elasmobranchs) known to possess a calcitonin-producing organ. Serum calcitonin concentrations were measured in 28 reproductively mature female S. tiburo using a heterologous enzyme-linked immunosorbent assay (ELISA) system. Sites of calcitonin immunoreactivity were detected in tissues of mature female and embryonic S. tiburo using immunocytochemistry. Significant increases in serum calcitonin concentrations of mature female S. tiburo occurred during early stages of gestation, a period characterized by yolk-dependency of developing embryos. Immunoreactive calcitonin was detected in the duodenum and pancreas of embryonic S. tiburo sampled during the same period. The results from this study suggest that calcitonin obtained from endogenous and/or maternal sources may function in regulating yolk digestion in embryonic S. tiburo. Therefore, the association between calcitonin and reproduction in elasmobranchs may reflect an important role for this hormone in embryonic development. © 2003 Wiley-Liss, Inc., Cited By (since 1996):5, Fish and Fisheries
Calibration and evaluation of five indicators of benthic community condition in two California bay and estuary habitats
Calibration and evaluation of five indicators of benthic community condition in two California bay and estuary habitats
Many types of indices have been developed to assess benthic invertebrate community condition, but there have been few studies evaluating the relative performance of different index approaches. Here we calibrate and compare the performance of five indices: the Benthic Response Index (BRI), Benthic Quality Index (BQI), Relative Benthic Index (RBI), River Invertebrate Prediction and Classification System (RIVPACS), and the Index of Biotic Integrity (IBI). We also examine whether index performance improves when the different indices, which rely on measurement of different properties, are used in combination. The five indices were calibrated for two geographies using 238 samples from southern California marine bays and 125 samples from polyhaline San Francisco Bay. Index performance was evaluated by comparing index assessments of 35 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best. However, performance differences among several combinations were small enough that factors such as logistics can also become a consideration in index selection. © 2008 Elsevier Ltd. All rights reserved., Cited By (since 1996):15, Invertebrates, CODEN: MPNBA
California State Waters Map Series—Offshore of Pigeon Point, California
California State Waters Map Series—Offshore of Pigeon Point, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology.
Can ecosystem-based deep-sea fishing be sustained? Report of a Workshop Held 31 August-3 September 2010
Can ecosystem-based deep-sea fishing be sustained? Report of a Workshop Held 31 August-3 September 2010
Downloaded from: digitalcommons.library.umaine.edu (20 August 2014). Darling Marine Center Special Publication 11-1, The University of Maine, 84 pages.
Can stormwater be detected by algae in an urban reef in Hawai'i?
Can stormwater be detected by algae in an urban reef in Hawai'i?
Nitrogen (N) enrichment of tropical reefs can result in the dominance of invasive algae. The invasive alga Acanthophora spicifera and the native alga Laurencia nidifica are part of a diverse reef assemblage in 'Ewa Beach, O'ahu. Their N contents and δ15N values were investigated to determine if N was enriched and to evaluate potential nitrogenous sources near and removed from storm-drain outlets. δ15N values of algae (3.8-17.7‰) were within and above the range for algae around the island (1.9-11.9‰). Elevated algae N isotope values (δ15N>+7‰, [N]>1.6%) and seawater nitrate+nitrite levels (0.59-7.93μM) indicated a mixed, high nutrient environment. The overlap in δ15N values with multiple nitrogenous sources precluded identification. However, spatial and temporal patterns did not support stormwater as the dominant, nitrogenous source. Patterns were congruent with algal incorporation of terrestrial derived N, subjected to a high degree of biogeochemical cycling. © 2013 Elsevier Ltd., Seaweeds, CODEN: MPNBA

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