排序方式： 共有3条查询结果，搜索用时 15 毫秒
1
1.
The physico-chemical characteristics of habitats have been considered to be one of the prime determinants of animal distribution within hydrothermal vent sites. However, the relative importance of abiotic to biotic influences is still debated. The primary aim of this study is twofold. The first is to determine and compare the ranges of physico-chemical conditions that characterize mussel-dominated and tubeworm-dominated communities at different sites within the vent field of the 9°50′N segment on the East Pacific Rise. The second is to better understand the processes that determine the variability of physico-chemical conditions in these habitats. In situ chemical and temperature measurements confirmed the high variability on small spatial and temporal scales within single aggregations of animals. The correlation of temperature and sulfide or pH revealed substantial differences between similar habitat-types at different sites, which cannot be attributed to changes in the extent of fluid dilution in the subseafloor. Further investigation of habitat variability within individual sites highlighted specific chemical features for the four sites studied, emphasizing the importance of an extensive in situ chemical analyses survey before using temperature as a proxy for chemical conditions. At Tica and Biovent, the fluid source characteristics were shown to vary only slightly within the sites, among aggregations discretely distributed over several meters distance. The variability of the total sulfide concentration and chemical speciation with temperature in the various habitats at each of these sites, can be reasonably simulated from the conservative mixing model of a single source fluid with seawater. The small variation of the empirical trends between different types of faunal assemblages at Tica suggests that changes in the fluid chemistry are not a prime determinant of the temporal succession of mussels and tubeworms. The findings of very similar sulfide–temperature relationships in two sites of different age and faunal compositions, Biovent and Tica, further support this idea. The two other sites, Mussel Bed and Riftia Field, differ both in the animal communities present and their chemistries show significant discrepancies from the predictions of the conservative mixing model. At Riftia Field, elevated iron concentrations and relatively low sulfide levels were correlated to unusually low pH, which could not be fully explained by conservative mixing of a typical diffuse vent fluid with seawater. The increased acidity results in a dramatic reduction in the anionic form, HS−. This is the form preferentially assimilated by the tubeworms and could explain the decline of the tubeworms at this site. At Mussel Bed the relationship between the sulfide concentration and temperature varied substantially among the aggregations surveyed and may reflect the influence of associated free-living microbial communities on the chemistry of mussel habitats. This study emphasizes the complex interplay of diffuse fluid formation in subsurface, chemical reactivity in the mixing zone, and biological activity in controlling of characteristics of vent habitats. 相似文献
2.
Garth L. Brand Robin V. Horak Nadine Le Bris Shana K. Goffredi Susan L. Carney Breea Govenar & Paul H. Yancey 《Marine Ecology》2007,28(1):208-218
Vesicomyid clams, vestimentiferans, and some bathymodiolin mussels from hydrothermal vents and cold seeps possess thiotrophic endosymbionts, high levels of hypotaurine and, in tissues with symbionts, thiotaurine. The latter, a product of hypotaurine and sulfide, may store and/or transport sulfide non‐toxically, and the ratio to hypotaurine plus thiotaurine (Th/[H + Th]) may reflect an animal's sulfide exposure. To test this, we analyzed seep and vent animals with in situ sulfide measurements. Calyptogena kilmeri clams occur at high‐sulfide seeps in Monterey Canyon, while C. (Vesicomya) pacifica clams occur at seeps with lower levels but take up and metabolize sulfide more effectively. From one seep where they co‐occur, both had gill thiotaurine contents at 22–25 mmol kg−1 wet mass, and while C. (V.) pacifica had a higher blood sulfide level, it had a lower Th/[H + Th] (0.39) than C. kilmeri (0.63). However, these same species from different seeps with lower sulfide exposures had lower ratios. Bathymodiolus thermophilus [East Pacific Rise (EPR 9°50′ N)] from high‐(84 μm ) and a low‐(7 μm ) sulfide vents had gill ratios of 0.40 and 0.12, respectively. Trophosomes of Riftia pachyptila (EPR 9°50′ N) from medium‐(33 μm ) and low‐(4 μm ) sulfide vents had ratios of 0.23 and 0.20, respectively (not significantly different). Ridgeia piscesae vestimentiferans (Juan de Fuca Ridge) have very different phenotypes at high‐ and low‐sulfide sites, and their trophosomes had the greatest differences: 0.81 and 0.04 ratios from high‐ and low‐sulfide sites, respectively. Thus Th/[H + Th] may indicate sulfide exposure levels within species, but not in interspecies comparisons, possibly due to phylogenetic and metabolic differences. Total H + Th was constant within each species (except in R. piscesae); the sum may indicate the maximum potential sulfide load that a species faces. 相似文献
3.
Habitat created or modified by the physical architecture of large or spatially dominant species plays an important role in structuring communities in a variety of terrestrial, aquatic, and marine habitats. At hydrothermal vents, the giant tubeworm Riftia pachyptila forms large and dense aggregations in a spatially and temporally variable environment. The density and diversity of smaller invertebrates is higher in association with aggregations of R. pachyptila than on the surrounding basalt rock seafloor. Artificial substrata designed to mimic R. pachyptila aggregations were deployed along a gradient of productivity to test the hypothesis that high local species diversity is maintained by the provision of complex physical structure in areas of diffuse hydrothermal flow. After 1 year, species assemblages were compared among artificial aggregations in low‐, intermediate‐, and high‐productivity zones and compared to natural aggregations of R. pachyptila from the same site. Hydrothermal vent fauna colonized every artificial aggregation, and both epifaunal density and species richness were highest in areas of high chemosynthetic primary production. The species richness was also similar between natural aggregations of R. pachyptila and artificial aggregations in intermediate‐ and high‐productivity zones, suggesting that complex physical structure alone can support local species diversity in areas of chemosynthetic primary production. Differences in the community composition between natural and artificial aggregations reflect the variability in microhabitat conditions and biological interactions associated with hydrothermal fluid flux at low‐temperature hydrothermal vents. Moreover, these local ecological factors may further contribute to the maintenance of regional species diversity in hydrothermal vent communities on the East Pacific Rise. 相似文献
1