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Western Gulf (western + gulf)
Selected AbstractsDetection of nodularin in flounders and cod from the Baltic SeaENVIRONMENTAL TOXICOLOGY, Issue 2 2001Vesa Sipiä Abstract The brackish water cyanobacterium Nodularia spumigena regularly forms waterblooms in the Baltic Sea. Many N. spumigena strains can produce nodularin, a hepatotoxic penta-peptide, which has caused several animal poisonings in the Baltic Sea area. To improve our understanding of nodularin bioaccumulation in aquatic organisms this study measured nodularin in flounder and cod caught from the Baltic Sea. Flounders were collected from the western Gulf of Finland in July 1996, September 1997, and September 1998, and from the Gulf of Bothnia in August 1997 and September 1998. Flounders were also collected from the coastal areas of Sweden in the Baltic Proper during September 1998. Cod were caught from the southern Baltic Sea in August 1998. Livers and muscles of the 1997 fish were isolated, extracted, and analysed for nodularin using high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) and protein phosphatase 1 (PP1) inhibition assay. Approximately 30,70 ng of nodularin/g dry weight (maximum value 140 ng/g) were found in the liver tissue samples by ELISA and PP1 inhibition. These concentrations were below the detection limit of HPLC. PP1 assay showed inhibition also in muscle samples, but this may due to other compounds present in the muscle extracts rather than NODLN or due to matrix interference. The recovery of nodularin from liver tissue with ELISA and PP1 assays was about 30%. Nodularin concentrations in samples are not corrected for recovery. Although the concentrations of nodularin found in this study are low further studies of nodularin are needed to assess possible bioaccumulation in brackish water food webs. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 121,126, 2001 [source] Microseismicity and faulting geometry in the Gulf of Corinth (Greece)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000Denis Hatzfeld During the summer of 1993, a network of seismological stations was installed over a period of 7 weeks around the eastern Gulf of Corinth where a sequence of strong earthquakes occurred during 1981. Seismicity lies between the Alepohori fault dipping north and the Kaparelli fault dipping south and is related to both of these antithetic faults. Focal mechanisms show normal faulting with the active fault plane dipping at about 45° for both faults. The aftershocks of the 1981 earthquake sequence recorded by King et al. (1985) were processed again and show similar results. In contrast, the observations collected near the western end of the Gulf of Corinth during an experiment conducted in 1991 (Rigo et al. 1996), and during the aftershock studies of the 1992 Galaxidi and the 1995 Aigion earthquakes (Hatzfeld et al. 1996; Bernard et al. 1997) show seismicity dipping at a very low angle (about 15°) northwards and normal faulting mechanisms with the active fault plane dipping northwards at about 30°. We suggest that the 8,12 km deep seismicity in the west is probably related to the seismic,aseismic transition and not to a possible almost horizontal active fault dipping north as previously proposed. The difference in the seismicity and focal mechanisms between east and west of the Gulf could be related to the difference in the recent extension rate between the western Gulf of Corinth and the eastern Gulf of Corinth, which rotated the faults dipping originally at 45° (as in the east of the Gulf) to 30° (as in the west of the Gulf). [source] Southeast Alaska: oceanographic habitats and linkagesJOURNAL OF BIOGEOGRAPHY, Issue 3 2009Thomas Weingartner Abstract We provide an overview of the physical oceanographic and geological processes that affect marine biological habitats and production in the marine waters throughout the archipelago and continental shelf of Southeast Alaska. Given the paucity of regional data, our overview summarizes work done in adjacent regions of the Gulf of Alaska shelf and basin, and draws on research carried out in similar settings elsewhere. The geological setting, which critically influences the regional meteorology and oceanography, includes a narrow continental shelf, deep channels that permeate the archipelago, fjords, glaciers and a rugged, mountainous coast. The large-scale meteorology is influenced primarily by seasonal variations in the intensity and position of the Aleutian Low. Winds, freshwater runoff, tides and cross-shelf exchange control the regional oceanography. The large-scale flow field advects mass, heat, salt, nutrients and planktonic organisms northward from British Columbia (and even further south) to the northern Gulf of Alaska along the slope, shelf, and within the channels of Southeast Alaska. The deep channels permeating the island archipelago and narrow continental shelf facilitate communication between basin and interior waters. Water properties and flow fields are subject to large annual variations in response to similarly large variations in winds and coastal freshwater discharge. The complex geological setting leads to large spatial heterogeneity in the physical processes controlling the local circulation fields and mixing, thereby creating numerous and diverse marine biological habitats. These various circulation and mixing processes modify substantially Southeast Alaska water masses and thus influence marine ecosystem processes downstream over the northern and western Gulf of Alaska shelf. [source] Temperature and prey quality effects on growth of juvenile walleye pollock Theragra chalcogramma (Pallas): a spatially explicit bioenergetics approachJOURNAL OF FISH BIOLOGY, Issue 3 2007M. M. Mazur A bioenergetics model for juvenile age-0 year walleye pollock Theragra chalcogramma was applied to a spatially distinct grid of samples in the western Gulf of Alaska to investigate the influence of temperature and prey quality on size-specific growth. Daily growth estimates for 50, 70 and 90 mm standard length (LS) walleye pollock during September 2000 were generated using the bioenergetics model with a fixed ration size. Similarities in independent estimates of prey consumption generated from the bioenergetics model and a gastric evacuation model corroborated the performance of the bioenergetics model, concordance correlation (rc) = 0·945, lower 95% CL (transformed) (L1) = 0·834, upper 95% CL (transformed) (L2) = 0·982, P < 0·001. A mean squared error analysis (MSE) was also used to partition the sources of error between both model estimates of consumption into a mean component (MC), slope component (SC), and random component (RC). Differences between estimates of daily consumption were largely due to differences in the means of estimates (MC= 0·45) and random sources (RC= 0·49) of error, and not differences in slopes (SC= 0·06). Similarly, daily growth estimates of 0·031,0·167 g day,1 generated from the bioenergetics model was within the range of growth estimates of 0·026,0·190 g day,1 obtained from otolith analysis of juvenile walleye pollock. Temperature and prey quality alone accounted for 66% of the observed variation between bioenergetics and otolith growth estimates across all sizes of juvenile walleye pollock. These results suggest that the bioenergetics model for juvenile walleye pollock is a useful tool for evaluating the influence of spatially variable habitat conditions on the growth potential of juvenile walleye pollock. [source] Using the composite variables of reproductive morphology, histology and steroid hormones to determine age and size at sexual maturity for the thorny skate Amblyraja radiata in the western Gulf of MaineJOURNAL OF FISH BIOLOGY, Issue 5 2006J. A. Sulikowski Age at size was linked to sexual maturity in 77 male and 93 female thorny skates Amblyraja radiata from the western Gulf of Maine using three criteria: 1) gross reproductive morphology, 2) histology and 3) steroid hormone concentrations. Age-bias plots and the coefficient of variation from vertebral band counts suggested that the ageing method represented a non-biased and precise approach to the age assessment of A. radiata. Maturity ogives for males, based on data gathered for clasper length, circulating testosterone concentrations and proportion of mature spermatocysts within the testes, predicted that 50% maturity occurred at a total length (LT) of 865 mm and c. 10·90 years of age. For females, maturity ogives, based on data gathered for ovary mass, shell gland mass, follicle size and circulating oestradiol concentrations, predicted that 50% maturity occurred at 875 mm LT and c. 11·00 years of age. Collectively, the results suggest that analysis of several contemporaneous reproductive variables offers an accurate determination of sexual maturity in the thorny skate. [source] INCREASED SAMPLING FOR INFERRING PHYLOGEOGRAPHIC PATTERNS IN BOSTRYCHIA RADICANS/B.JOURNAL OF PHYCOLOGY, Issue 6 2006MORITZIANA (RHODOMELACEAE, RHODOPHYTA) IN THE EASTERN USA Zuccarello and West (2003) reported on the phylogenetic diversity of algae identified as Bostrychia radicans (Montagne) Montagne and B. moritziana (Sonder ex Kützing) J. Agardh from around the world. They showed that the species complex consisted of seven distinct lineages, of which two lineages were common on the East Coast of the USA and eastern Gulf of Mexico. The distribution of haplotypes within these lineages on the East Coast of the USA showed a general north,south distribution. One haplotype of lineage 5 (B) was mostly collected in northern areas, while the other common haplotype (C) was more southerly in distribution. Samples in lineage 6 (haplotype D) were not found north of Sapelo Island, Georgia. Increased sampling from the eastern USA over 5 years later has revealed an altered pattern. Haplotype D is distributed in North Carolina and is common in some populations. Haplotype C is rare or absent in many sampled populations. Haplotype B is only observed in the northern sampled sites on both sides of the Florida peninsula. This disjunct distribution agrees with geological scenarios for a strait between the western Gulf of Mexico and southern Georgia in the Miocene/Pliocene, which closed in the late Pliocene. This paper highlights the importance of increased sampling to determine phylogeographic patterns and hypotheses of dispersal scenarios in algae. [source] PHYLOGENETIC AND BIOGEOGRAPHIC AFFINITIES OF THE HALYMENIALES AND RHODYMENIALES (RHODOPHYTA) FROM THE GULF OF MEXICOJOURNAL OF PHYCOLOGY, Issue 2000B. Gavio Generic and species concepts within the red algal assemblages Halymeniales and Rhodymeniales are discussed for taxa inhabiting the western Gulf of Mexico. Two principal biogeographic assemblages occur: an off-shore deep-water group (including Coelarthrum cliftonii, Halymenia spp., Botryocladia spp., Gloiocladia) representing remnants of a Tethyan distribution, and a near-shore intertidal flora (comprising Rhodymenia, Grateloupia and Prionitis) which instead reveals biogeographic affinities with the Carolinian Province. These two distinct marine floras will be contrasted phylogenetically based on DNA sequence analysis inferred from chloroplast-encoded rbcL. The generic descriptions of Grateloupia and Prionitis are in need of taxonomic revision based on a survey of species from Caribbean and Pacific Mexico. [source] Osmoregulation in Six Sympatric Fiddler Crabs (genus Uca) from the Northwestern Gulf of MexicoMARINE ECOLOGY, Issue 4 2002Carl L. Thurman Abstract. As problems in taxonomy and systematic relationships among the Uca species are resolved, a definition of how each fiddler crab species partitions and utilizes habitat resources is needed. To this end, the osmoregulatory capabilities were studied in six species of fiddler crabs from the western Gulf of Mexico. Specimens were placed in 50,ml of artificial seawater ranging in osmolality from 50 to 3450,mOsm (2 to 109,,) for five days. Survivorship was recorded for each species. Uca rapax, U. panacea and U. subcylindrica are hardy from 200 to 3200,mOsm (6 to 101,,). Uca spinicarpa and U. minax survive only below 1400,mOsm (44,,). U. longisignalis is intermediate, with limited survival above 2500,mOsm (79,,). Hemolymph osmolality was determined for crabs surviving the osmotic regimen. Uca panacea, U. subcylindrica and U. rapax are equivalent in their regulation between 50 and 3200,mOsm (2,,,101,,). Uca longisignalis lost its ability to control hemolymph osmolality above 2200,mOsm (69,,). On the other hand, U. spinicarpa and U. minax become less effective hyporegulators in media above 1200 (38,,) and 1500,mOsm (47,,), respectively. Only U. longisignalis appears to exhibit clear differences in osmoregulatory capacity between populations. Population data for U. panacea and laboratory experiments with U. subcylindrica also support the notion of capacitative acclimation in Uca. These physiological capabilities correlate well with the known habitat characteristics for each fiddler crab species in the northwestern Gulf of Mexico. [source] Sperm whale depredation of sablefish longline gear in the northeast Pacific OceanMARINE MAMMAL SCIENCE, Issue 1 2008Michael F. Sigler Abstract Interactions between marine mammals and fisheries include competition for prey (catch), marine mammal entanglement in fishing gear, and catch removal off fishing gear (depredation). We estimated the magnitude of sperm whale depredation on a major North Pacific longline fishery (sablefish) using data collected during annual longline surveys. Sperm whale depredation occurs while the longline gear is off-bottom during retrieval. Sperm whales were observed on 16% of longline survey sampling days, mostly (95% of sightings) over the continental slope. Sightings were most common in the central and eastern Gulf of Alaska (98% of sightings), occasional in the western Gulf of Alaska and Aleutian Islands, and absent in the Bering Sea. Longline survey catches were commonly preyed upon when sperm whales were present (65% of sightings), as evidenced by damaged fish. Neither sperm whale presence (P= 0.71) nor depredation rate (P= 0.78) increased significantly from 1998 to 2004. Longline survey catch rates were about 2% less at locations where depredation was observed, but the effect was not significant (P= 0.34). Estimated sperm whale depredation was <1% of the annual sablefish longline fishery catch off Alaska during 1998 to 2004. [source] | |||||||||||||