148 research outputs found
Temporal and spatial variation in the reproductive ecology of the vent-endemic amphipod Ventiella sulfuris in the eastern Pacific
No full textPopulations of the vent-endemic amphipod Ventiella sulfuris were compared from 6 East Pacific Rise (EPR) vent sites of different ages, 3 from the northern EPR and 3 from the southern EPR. Although vent age affected amphipod abundance, with no individuals at the oldest vent, other population/reproductive parameters were found to be site dependent rather than vent age dependent. There was little within-site variation in population structure and reproductive output, probably the result of high within-site motility. However, there were significant between-site and between-field differences, indicating a high degree of population and reproductive variability and a moderate degree of vent fidelity. Since population structure and reproductive output varied between sites, the possibility of their use as biomarkers of vent ‘condition’ is discussed. The reproductive ecology of V. sulfuris is described for the first time and compared to that of other vent amphipod species. Unlike other species studied, reproductive output is relatively high. Adults move to the periphery of vents to reproduce and brood; after brooding, they moult again, return to feed at vent habitats (e.g. mussel and tube worm beds), and undergo a new phase of gonad maturation and emigration
Reproductive ecology of Bouvierella curtirama (Amphipoda: Eusiridae) from chemically distinct vents in the Lucky Strike vent field, Mid-Atlantic Ridge
No full textPopulations of the vent amphipod Bouvierella curtirama were compared from two sites in the Lucky Strike vent field on the Mid-Atlantic Ridge. The two sites (Sintra and Eiffel Tower) are chemically distinct, fed by different hydrothermal sources, but separated by only about 400 m. Both sites are characterized by dense beds of the mussel Bathymodiolus azoricus, though the proportion of methanotrophic and thiotrophic endosymbionts supported by the mussel and its isotopic composition vary significantly between the sites. Such differences presumably reflect the availability of primary resources and would be expected to impinge on other members of the mussel bed community, such as B. curtirama, which was abundant at both sites. A detailed comparative study of the amphipod showed that, although the overall population structure (in terms of growth stages) was similar at the two sites, reproductive output was significantly greater at Sintra, a result of females maturing at a smaller body size and producing more broods of a greater size. The reproductive output at both sites was relatively low, with a proportion of surviving females failing to mature. The plasticity of response of the two populations is discussed in relation to food availability (quantity and quality). Grazing predation, resulting in loss of antennal flagellum articles, was high at both sites. Such damage is discussed in terms of predation impact. Damage to the antennae of the holotype has resulted in an inaccurate species description, which is remedied here
Lipid composition of the hydrothermal vent clam Calyptogena pacifica (Mollusca: Bivalvia) as a trophic indicator
No full textStructure and function of Halice hesmonectes (Amphipoda: Paraliscidae) swarms from hydrothermal vents in the eastern Pacific
No full textSwarms of the pardaliscid amphipod Halice hesmonectes were sampled at low-temperature hydrothermal vents in the Venture Hydrothermal Fields of the East Pacific Rise. In excess of 3000 individuals were collected from a range of sites/habitats, and at two points in time (December 1991 and March 1994). The structure of swarms was described in terms of growth stages, the development of primary and secondary sex characteristics and the accumulation of nutritional reserves. The results demonstrated that swarms contained a wide range of growth stages, but that small juveniles and mature males and females were absent. Swarm structure was interpreted as an equilibrium dependent on the relative proportion of time spent by each growth stage in the swarm habitat. This equilibrium swarm structure was very similar at different sites and times. Swarms dominated by small juveniles occurred at the northern sites in December 1991 following a period of eruption and new venting in April 1991. Equilibrium swarm structure had become re-established at these sites by March 1994. The function of swarming was considered. The results indicated that swarming was not associated with reproductive activity. The available evidence, though not conclusive, suggested that swarms were associated with feeding
Diversity of meiofauna and free-living nematodes in hydrothermal vent mussel beds on the northern and southern East Pacific Rise
No full textThe ecology and biogeography of meiofauna at deep-sea hydrothermal vents have historically received less attention that those of mega- and macrofauna. This study examines the composition of major meiofaunal taxa in beds of the mussel Bathymodiolus thermophilus at hydrothermal vents on the northern and southern East Pacific Rise (EPR) and presents the first comparison of species assemblages of the dominant taxon, the nematodes, among sites spanning 27 degrees of latitude. Meiofaunal samples were collected by submersible from three mussel beds at 9°N on the EPR and four mussel beds between 17 and 18°S in 1999. Estimated ages of the mussel beds at the time of sampling range from 4 to >20 years, enabling investigation of influence of mussel bed age on meiofaunal assemblages. Overall, the meiofauna of the mussel beds was dominated by nematodes, with copepods constituting the second most abundant meiofaunal group. There was variation in the ratio of nematodes to copepods between sites, however, with copepods more abundant than nematodes in the youngest mussel beds. Apart from polychaete larvae, other meiofaunal groups were generally present at very low abundance (< 1 %) in the samples and restricted in diversity to gastropod larvae, acari, foraminifera, ostracoda and turbellaria. Seventeen nematode species from 14 genera and 11 families were found in the samples, with no evidence of endemicity to hydrothermal vents at the generic level. Four genera present were not previously recorded at hydrothermal vents. Nematode species richness, species:genus ratios and abundances were low compared with other deep-sea habitats, though the ecological relevance of comparisons with soft-sediment benthos is discussed. Nematode assemblages exhibited high dominance by a few species, with one species of Thalassomonhystera most abundant at 5 of the 7 vent sites. Multivariate analysis of nematode assemblages reveals similarities among sites that do not match geographical proximity. The youngest mussel beds were most similar to each other and exhibited lower species richness than other sites, consistent with colonisation of mussel bed habitat by nematodes over time. Similarity in the composition of nematode assemblages among sites separated by ~3000 km indicates that they lie within a single biogeographic province, consistent with that proposed for mussel bed macrofauna. At a generic level, samples exhibited some overlap with nematode assemblages at vents elsewhere on the East Pacific Rise, on the Mid-Atlantic Ridge and in the North Fiji Basin
Evolution and biogeography of deep-sea vent and seep invertebrates
No full textDeep-sea hydrothermal vents and cold seeps are submarine springs where nutrient-rich fluids emanate from the sea floor. Vent and seep ecosystems occur in a variety of geological settings throughout the global ocean and support food webs based on chemoautotrophic primary production. Most vent and seep invertebrates arrive at suitable habitats as larvae dispersed by deep-ocean currents. The recent evolution of many vent and seep invertebrate species (<100 million years ago) suggests that Cenozoic tectonic history and oceanic circulation patterns have been important in defining contemporary biogeographic patterns. <br/
Origins of long-chain polyunsaturated fatty acids in the hydrothermal vent worms Ridgea piscesae and Protis hydrothermica
No full textBook Review: The Ecology of Deep-Sea Hydrothermal Vents
No full textBook Title: The Ecology of Deep-Sea Hydrothermal VentsBook Author: C.L. van Dover. Princeton University Press, Princeton, New Jersey. 2000. Pp. 424. Price£24.95 (paperback). ISBN 0-691-05780-X
An ecosystem-based deep-ocean strategy
No full textIncreasing exploration and industrial exploitation of the vast and fragile deep-ocean environment for a wide range of resources (e.g., oil, gas, fisheries, new molecules, and soon, minerals) raises global concerns about potential ecological impacts (1–3). Multiple impacts on deep-sea ecosystems (>200 m below sea level; ?65% of the Earth's surface is covered by deep ocean) caused by human activities may act synergistically and span extensive areas. Cumulative impacts could eventually cause regime shifts and alter deep-ocean life-support services, such as the biological pump or nutrient recycling (2, 4, 5). Although international law and national legislation largely ignore the deep sea's critical role in the functioning and buffering of planetary systems, there are promising developments in support of deep-sea protection at the United Nations and the International Seabed Authority (ISA). We propose a strategy that builds from existing infrastructures to address research and monitoring needs to inform governments and regulators
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