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The Eiffel Tower edifice is situated in the Lucky Strike hydrothermal vent field at a mean depth of 1690 m on the Mid‐Atlantic Ridge (MAR). At this 11‐m‐high hydrothermal structure, different faunal assemblages, varying in visibly dominant species (mussels and shrimp), in mussel size and in density of mussel coverage, were sampled biologically and chemically. Temperature and sulphide (∑S) were measured on the different types of mussel‐based assemblages and on a shrimp‐dominated assemblage. Temperature was used as a proxy for calculating total concentrations of CH4. Based on the physico‐chemical measurements, two microhabitats were identified, corresponding to (i) a more variable habitat featuring the greatest fluctuations in environmental variables and (ii) a second, more stable, habitat. The highest temperature variability and the highest maximum recorded temperatures were found in the assemblages visibly inhabited by alvinocaridid shrimp and dense mussel beds of large Bathymodiolus azoricus, whereas the less variable habitats were inhabited by smaller‐sized mussels with increasing bare surface in between. Larger mussels appeared to consume more ∑S compared with smaller‐sized (<1 cm) individuals and thus had a greater influence on the local chemistry. In addition, the mussel size was shown to be significantly positively correlated to temperature and negatively to the richness of the associated macrofauna. The presence of microbial mats was not linked to specific environmental conditions, but had a negative effect on the presence and abundance of macro‐fauna, notably gastropods. Whereas some taxa or species are found in only one of the two microhabitats, others, such as polychaetes and Mirocaris shrimp, cross the different microhabitats. Temperature was proposed to be a more limiting factor in species distribution than ∑S.  相似文献   

3.
The turbulent mixing of hydrothermal hot fluid with cold seawater creates large chemical gradients at a small spatial scale that may induce variable physiological and biochemical adaptations within the vent fauna. The adaptation to such a variable environment by the vent mussel Bathymodiolus azoricus relies on a dual symbiosis hosted in the gills, and digestion of particulate organic matter. The surrounding environment not only provides the necessary energy sources and suspended organic particles for the vent mussel nutrition, but also potentially toxic compounds such as metals. Our main goal was to see if there is a relation between metal accumulation in mussel organs and the chemical characteristics of their close environment. Mussels were collected at six locations in a cold part of the Eiffel Tower fluid-seawater mixing zone, characterized by distinct chemical compositions. Metals (Cd, Cu, Fe and Zn) and metallothioneins were quantified in the gills and digestive gland. The physiological condition of the sampled mussels was also evaluated using tissues and gill indices. Our study indicates that the accumulation of metals in B. azoricus is related to their spatial distribution and linked to fine scale environmental conditions that influence the physiological status of the organism.  相似文献   

4.
In the past few decades, hydrothermal vent research has progressed immensely, resulting in higher-quality samples and long-term studies. With time, scientists are becoming more aware of the impacts of sampling on the faunal communities and are looking for less invasive ways to investigate the vent ecosystems. In this perspective, imagery analysis plays a very important role. With this study, we test which factors can be quantitatively and accurately assessed based on imagery, through comparison with faunal sampling. Twelve instrumented chains were deployed on the Atlantic Eiffel Tower hydrothermal edifice and the corresponding study sites were subsequently sampled. Discrete, quantitative samples were compared to the imagery recorded during the experiment. An observer-effect was tested, by comparing imagery data gathered by different scientists. Most factors based on image analyses concerning Bathymodiolus azoricus mussels were shown to be valid representations of the corresponding samples. Additional ecological assets, based exclusively on imagery, were included.  相似文献   

5.
Although the spatial distribution of hydrothermal vent assemblages in relation to environmental conditions has been assessed in several studies, there is little documented data on the temporal variation of the fauna and corresponding abiotic factors in a vent community. Here, we present one of the longest integrated (faunal and environmental data) time series ever obtained in a hydrothermal ecosystem. The data were acquired using the TEMPO ecological module that was deployed between 2006 and 2008 on the Mid-Atlantic Ridge, providing the first insights into the day-to-day variations in a Bathymodiolus azoricus mussel assemblage from the Lucky Strike vent field for the 48 days during which the video camera operated. The time-series yielded additional valuable information on longer-term variation in faunal distribution (comparing ~2 years), temperature (11.7 months) and iron concentrations (3.8 months).Results from daily observations showed that the vent mussel assemblage was quite stable over the 48 days of the study, reflecting the relative stability of environmental conditions during this period. B. azoricus mussels appeared to thrive in areas of very limited hydrothermal fluid input in habitats that are, as in other deep-sea ecosystems, significantly influenced by ocean tidal signals. Variation in species abundance was observed but, with the exception of Mirocaris fortunata shrimp, no links could be established with measured environmental variables. Although we did not observe any clear tidal influence on vent fauna, it is likely that physiological processes and species’ activities are influenced by these periodic variations. Longer time series are currently being acquired by different experiments deployed on the EMSO-Açores MoMAR observatory (2010–2013 and still recording). They should further improve our knowledge of the dynamics of hydrothermal systems and their associated faunal communities.  相似文献   

6.
In 2006, paired wood and slate panels, each equipped with a temperature probe, were deployed on three different localities on and around the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) within close proximity of visible hydrothermal activity. Recovery of these panels took place in 2008. For this two-year deployment period, the composition of colonising organisms (both macro-and meiofauna) was assessed, along with image analyses of the deployment sites in 2006 and 2008. Very few significant differences in colonisation between organic (wood) and inorganic (slate) panels were revealed. Rather, the locality of deployment and the local environmental conditions and hydrothermal activity were found to influence taxonomic composition. Variability in microhabitat conditions and biological interactions were hypothesised to interact jointly in shaping new faunal communities on the colonisation substrata.  相似文献   

7.
Near the Azores Triple Junction as the Azores Plateau is approached, the ridge axis becomes shallower; its depth decreases from ca. 2400 m in the Rainbow vent field (36°13′N) to ca. 850 m in the Menez Gwen vent field (37°35′N). In this area, extensive mussel beds of the mytilid Bathymodiolus azoricus dominate the hydrothermal vent fauna, along with populations of three shrimps (Rimicaris exoculata, Mirocaris fortunata and Chorocaris chacei). The main physical and chemical characteristics of the vent habitat were studied by discrete sampling, in situ analysis and sediment trap moorings. The vent fauna is distributed along a variable band where the vent fluids and seawater mix, with R. exoculata living in the most concentrated areas and Bathymodiolus azoricus in the most diluted zones. Various non-endemic species live at the border of the vent field. The variations observed in structure and composition of the communities along the depth gradient are most likely due to changes in vent fluid toxicity (metallic and sulphide content) and suspended mineral particles, which render the fluids harsher for species living there. The main faunal differences observed between Lucky Strike and Menez Gwen hydrothermal fields are due to an impoverishment in the hydrothermal endemic species and to the penetration of bathyal species. The comparison of the three studied vent fields suggests the existence of a succession of several biogeographic islands rather than a single province.  相似文献   

8.
Macrofaunal assemblages with the prevalence of Bresiliidae shrimp and Mytilidae mussels are abundant in the hydrothermal vents along the Mid-Atlantic Ridge. The mussels inhabit the zone of diffuse seeps of hydrothermal fluids with temperature abnormalities up to several degrees. Shrimps inhabit an extreme biotope in the mixed interface between the seawater and the hydrothermal fluid at a temperature up to 20–30°C. We studied the mussel and shrimp assemblages in three hydrothermal vent fields: the Rainbow, Broken Spur, and Snake Pit. The species richness of the mussel assemblages in at least two regions (Broken Spur and Snake Pit) is higher as compared with the shrimps of the same hydrothermal vent fields. The fauna inhibiting the shrimp swarms lack almost any taxa specific for particular assemblages: almost all the taxa are also present in the mussel beds. The structure of the shrimp assemblage is less homogeneous as compared with that of the mussel assemblage. The population prevalence of one taxon (Copepoda) in the shrimp assemblage is most likely connected with the extreme and unstable conditions of the biotope occupied by the shrimps in the hydrothermal field. The taxonomic similarity between the mussel and shrimp assemblages within one hydrothermal vent field is higher as compared with the similarity between the mussel (or shrimp) assemblages from different fields.  相似文献   

9.
The structure of the assemblages associated with the mussel aggregations of Bathymodiolus azoricus was investigated. The mussel beds were found on the hydrothermal vent fields on the Mid-Atlantic Ridge (the Menez Gwen, Lucky Strike, and Rainbow areas) at the depths of 850–2400 m. The community structure of the mussel bed assemblages varied between the studied areas. Large number of species was unique to Menez Gwen mussel beds; the most observed taxa were not specialized hydrothermal species. All the other, nonunique species were found for the Lucky Strike region. The lowest mussel assemblage structure evenness was observed in the shallowest area, the Menez Gwen area (850 m depth). We assume that two types of mussel assemblages—nematode-dominated and copepod-dominated ones—exist in the Lucky Strike field. The assemblages of B. azoricus differ significantly from the assemblages of B. thermophilus inhabiting the Pacific hydrothermal vents.  相似文献   

10.
“CHEMINI” is a new instrument developed for the measurement of seawater chemical parameters. It is a mono-parameter in situ chemical analyzer based on flow injection analysis and colorimetric detection. The deep-sea version of CHEMINI combines two modules to perform the analysis of dissolved iron [Fe (II) or Fe (II+III)] and total sulphide (H2S+HS?+S2?) up to 6000 m depth. Detection limits are, respectively, 0.3 and 0.1 μM for iron and sulphide. The system proved highly reliable during the MoMARETO cruise on the Mid-Atlantic Ridge. The two CHEMINIs were used to describe the chemical environment in 12 mussel beds on the Tour Eiffel hydrothermal edifice.  相似文献   

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