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Marine Fauna (marine + fauna)
Selected AbstractsLessons from the past: the collapse of Jamaican coral reefsFISH AND FISHERIES, Issue 2 2009Marah J. Hardt Abstract Since Pre-Columbian times, humans have exploited Jamaican marine ecosystems with significant consequences for flora and fauna. This study focuses on the history of reef fish exploitation in Jamaica, from first human occupation to the present day, to determine how past fishing activities contributed to subsequent declines in the coral reef ecosystem. The pattern of declining reef fish populations was nonlinear. Reef fish first declined in prehistoric times but then potentially recovered, following genocide of the native human population. Reduced fishing pressure lasted until the mid-19th century. At that time, depletion of reef fish populations again occurred with a precipitous decline from the 1850s to the 1940s. The final shift from relatively abundant to overfished marine fauna corresponded to subtle changes in fish trap design as well as development of recreational fishing. Government subsidies throughout the second half of the 20th century exacerbated the declines. This analysis shows that local artisanal fisheries with relatively low levels of effort and seemingly subtle shifts in technology can significantly impact the coral reef ecosystem and that declines occurred decades to centuries before modern ecological studies began. This research shows how historical analysis can be a powerful tool to minimize shifted baselines and establish realistic targets for recovery and sustainable management of marine ecosystems. [source] Length and sex-specific associations between spiny dogfish (Squalus acanthias) and hydrographic variables in the Bay of Fundy and Scotian ShelfFISHERIES OCEANOGRAPHY, Issue 2 2002Travis Shepherd The associations between spiny dogfish (Squalus acanthias) and hydrographic variables (temperature, salinity and depth) were examined in the Bay of Fundy and Scotian Shelf from 1970 to 1998. Data were obtained from standard groundfish bottom trawl surveys. Dogfish sex affected habitat associations. Males were found to occupy bottom water of significantly higher salinities and depths than that occupied by females. Length also significantly affected habitat associations. Smaller dogfish occupied relatively deep, high salinity bottom water compared with larger dogfish. Overall, the occupied temperatures, salinities and depths were significantly different from those which were available. Dogfish occupied warmer temperatures along a narrow range (6.62,9.19°C) compared with those which were available (1.57,9.35°C). Occupied salinity (32.70,34.43 ppt) and occupied depth (88.62,184.66 m) were also distributed along a narrower range than available salinity (32.16,34.79 ppt) and available depth (55.00,218.10 m). Sex-specific, length-specific and overall environmental preference by dogfish may bias traditional `offshore' groundfish surveys while large scale changes in hydrographic parameters may alter dogfish distribution and their interactions with other marine fauna. [source] Recognition of southern Gondwanan palynomorphs at Gondwana's northern margin,and biostratigraphic correlation of Permian strata from SE Turkey and AustraliaGEOLOGICAL JOURNAL, Issue 2-3 2010Ellen Stolle Abstract This study focuses on the palynology of Guadalupian (Middle Permian) strata of SE Turkey, especially on late Wordian and earliest Capitanian deposits, which are dated by foraminifers and can be chronostratigraphically related to the geological timescale. Herein, palynological species, such as Altitriletes densus, Cymatiosphaera gondwanensis and Praecolpatites sinuosus, previously characteristic for Pakistan, Australia and Antarctica are recorded. Therefore, the Permian biozones of marine fauna and the palynology of SE Turkey and the rest of the Arabian area and Australia are compared and correlated. This long-distance, eastern Gondwana-wide biostratigraphical correlation, conducted for the first time in the Guadalupian epoch in this study, showed that Corisaccites alutas has a similar Last Occurrence Datum in SE Turkey and in Australia. The correlation also showed that in the late Wordian a number of species were present throughout eastern Gondwana, whereas the distribution of other certain species was influenced by provincialism. Hence, it may be concluded that certain species of parent plants probably co-occurred Gondwana-wide, while the distribution of others was dependant on climate. Copyright © 2010 John Wiley & Sons, Ltd. [source] Body size-dependent responses of a marine fish assemblage to climate change and fishing over a century-long scaleGLOBAL CHANGE BIOLOGY, Issue 2 2010MARTIN J. GENNER Abstract Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long-term changes in species abundance and body-size distributions. In this study, we investigated long-term (1911,2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger-growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller-growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size-dependent responses of species to long-term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size-selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna. [source] Seven Decades of Change in the Zooplankton (s.l.) of the Nile Delta Lakes (Egypt), with Particular Reference to Lake BorullusINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2008Henri J. Dumont Abstract Around the 1930s, the zooplankton (and benthos) of the Nile delta lakes, and Lake Borullus in particular, had a mixed, eutrophic facies, with marine and mesohaline elements dominant for about eight months per year, and freshwater species taking over during the four months of the Nile flood. After the Aswan dam became operational, this regime changed: a steady supply of agricultural drainage water of Nilotic origin consistently freshened the delta. Thus, except in the immediate vicinity of their outlet to the sea, the lakes became almost fresh. Only during the rare and short-lived (one-three weeks) occasions when Aswan closes in winter, marine water is sucked in, and along with it, a saline fauna temporarily becomes re-established in the east and centre of lake Borullus, and presumably of the other delta lakes as well. This marine fauna remained the same over 70+ years of observations. The freshwater component, in contrast, partly nilotic, partly mediterranean, changed deeply over time. First, the fraction of species from temporary waters disappeared, as well as (among copepods and cladocerans) all large-bodied species. Several cladocerans and copepods with a euro-mediterranean range appeared and diluted the pre-existing Afrotropical fauna. The abundance of small cladocerans and, especially, rotifers increased by a factor ten or more. This latter change is believed to reflect two pressures. In a first phase, a re-arrangement of the lake's fish fauna (a top down force) occurred. Freshwater fish replaced marine diadromic species, and their predation pressure on the zooplankton preferentially removed large-bodied prey. In a second phase, increased agricultural drainage caused eutrophication (a bottom-up force) and larger filtrators (cladocerans, some copepods) began to be replaced by small filtrators (rotifers). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Deglaciation of the Irish Sea Basin: a critique of the glaciomarine hypothesisJOURNAL OF QUATERNARY SCIENCE, Issue 5 2001Danny McCarroll Abstract The glaciomarine model for deglaciation of the Irish Sea basin suggests that the weight of ice at the last glacial maximum was sufficient to raise relative sea-levels far above their present height, destabilising the ice margin and causing rapid deglaciation. Glacigenic deposits throughout the basin have been interpreted as glaciomarine. The six main lines of evidence on which the hypothesis rests (sedimentology, deformation structures, delta deposits, marine fauna, amino-acid ratios and radiocarbon dates) are reviewed critically. The sedimentological interpretation of many sections has been challenged and it is argued that subglacial sediments are common rather than rare and that there is widespread evidence of glaciotectonism. Density-driven deformation associated with waterlain sediments is rare and occurs where water was ponded locally. Sand and gravel deposits interpreted as Gilbert-type deltas are similarly the result of local ponding or occur where glaciers from different source areas uncoupled. They do not record past sea-levels and the ad hoc theory of ,piano-key tectonics' is not required to explain the irregular pattern of altitudes. The cold-water foraminifers interpreted as in situ are regarded as reworked from Irish Sea sediments that accumulated during much of the late Quaternary, when the basin was cold and shallow with reduced salinities. Amino-acid age estimates used in support of the glaciomarine model are regarded as unreliable. Radiocarbon dates from distinctive foraminiferal assemblages in northeast Ireland show that glaciomarine sediments do occur above present sea-level, but they are restricted to low altitudes in the north of the basin and record a rise rather than a fall in sea-level. It is suggested here that the oldest dates, around 17 000 yr BP, record the first Late Devensian (Weichselian) marine inundation above present sea-level. This accords with the pattern but not the detail of recent models of sea-level change. Copyright © 2001 John Wiley & Sons, Ltd. [source] Incongruent patterns of genetic connectivity among four ophiuroid species with differing coral host specificity on North Atlantic seamountsMARINE ECOLOGY, Issue 2010Walter Cho Abstract Seamounts are considered to play a defining role in the evolution and diversity of marine fauna, acting as ,stepping-stones' for dispersal, regional centers of genetic isolation and speciation, and refugia for deep-sea populations. This study focused on the patterns of dispersal and genetic connectivity of four seamount ophiuroid species (Asteroschema clavigera, Ophiocreas oedipus, Ophioplinthaca abyssalis, and Ophioplinthaca chelys) displaying differing levels of associative (epifaunal) specificity to cold-water coral hosts inhabiting the New England and Corner Rise Seamount chains, and Muir Seamount in the Northwestern Atlantic. Analyses of mt16S and mtCOI revealed evidence for recent population expansion and high gene flow for all four species. However, species-specific genetic differentiation was significant based on seamount region and depth. Significant differences were found among regional seamount groups for A. clavigera, within seamount regions and seamounts for O. chelys, among 250-m depth intervals for A. clavigera, among 100-m depth intervals for O. oedipus, and there were indications of isolation by distance for A. clavigera and O. oedipus. In addition, A. clavigera and O. oedipus, broadcast spawners with high fidelity to specific coral hosts, displayed predominantly westward historical migration, whereas the ophioplinthacids, with lower host-specificity, displayed predominantly eastward migration. No congruent patterns of historical migration were evident among species and seamounts, yet these patterns can be correlated with species-specific host specificity, specific depth strata, and dispersal strategies. Conservation efforts to protect seamount ecosystems should promote multi-species approaches to genetic connectivity, and consider the impact of the ,dependence' of biodiversity on host fauna in these vulnerable marine ecosystems. [source] Ex situ cultivation of Aplysinaaerophoba close to in situ conditions: ecological, biochemical and histological aspectsMARINE ECOLOGY, Issue 2 2008Anne Klöppel Abstract Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms , the sponge itself or associated microorganisms , are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites. [source] Quantitative evaluation of marine protein contribution in ancient diets based on nitrogen isotope ratios of individual amino acids in bone collagen: An investigation at the Kitakogane Jomon siteAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Yuichi I. Naito Abstract Nitrogen stable isotopes analysis of individual bone collagen amino acids was applied to archeological samples as a new tool for assessing the composition of ancient human diets and calibrating radiocarbon dates. We used this technique to investigate human and faunal samples from the Kitakogane shell midden in Hokkaido, Japan (5,300,6,000 cal BP). Using compound-specific nitrogen isotope analysis of individual amino acids, we aimed to estimate i) the quantitative contribution of marine and terrestrial protein to the human diet, and ii) the mean trophic level (TL) from which dietary protein was derived from marine ecosystems. Data were interpreted with reference to the amino acid trophic level (TLAA) model, which uses empirical amino acid ,15N from modern marine fauna to construct mathematical equations that predict the trophic position of organisms. The TLAA model produced realistic TL estimates for the Kitakogane marine animals. However, this model was not appropriate for the interpretation of human amino acid ,15N, as dietary protein is derived from both marine and terrestrial environments. Hence, we developed a series of relevant equations that considered the consumption of dietary resources from both ecosystems. Using these equations, the mean percentage of marine protein in the Kitakogane human diet was estimated to be 74%. Although this study is one of the first systematic investigations of amino acid ,15N in archeological bone collagen, we believe that this technique is extremely useful for TL reconstruction, palaeodietary interpretation, and the correction of marine reservoir effects for radiocarbon dating. Am J Phys Anthropol 143:31,40, 2010. © 2010 Wiley-Liss, Inc. [source] Late Quaternary history of the Kap Mackenzie area, northeast GreenlandBOREAS, Issue 3 2010BERND WAGNER Wagner, B., Bennike, O., Cremer, H. & Klug, M. 2010: Late Quaternary history of the Kap Mackenzie area, northeast Greenland. Boreas, Vol. 39, pp. 492,504. 10.1111/j.1502-3885.2010.00148.x. ISSN 0300-9483. The Kap Mackenzie area on the outer coast of northeast Greenland was glaciated during the last glacial stage, and pre-Holocene shell material was brought to the area. Dating of marine shells indicates that deglaciation occurred in the earliest Holocene, before 10 800 cal. a BP. The marine limit is around 53 m a.s.l. In the wake of the deglaciation, a glaciomarine fauna characterized the area, but after c. one millennium a more species-rich marine fauna took over. This fauna included Mytilus edulis and Mysella sovaliki, which do not live in the region at present; the latter is new to the Holocene fauna of northeast Greenland. The oldest M. edulis sample is dated to c. 9500 cal. a BP, which is the earliest date for the species from the region and indicates that the Holocene thermal maximum began earlier in the region than previously documented. This is supported by driftwood dated to c. 9650 cal. a BP, which is the earliest driftwood date so far from northeastern Greenland and implies that the coastal area was at least partly free of sea ice in summer. As indicated by former studies, the Storegga tsunami hit the Kap Mackenzie area at c. 8100 cal. a BP. Loon Lake, at 18 m a.s.l., was isolated from the sea at c. 6200 cal. a BP, which is distinctly later than expected from existing relative sea-level curves for the region. [source] | |||||||||||||