scholarly journals Increased diversity of sessile epibenthos at subtidal hydrothermal vents: seven hypotheses based on observations at Milos Island, Aegean Sea

2011 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Carlo Nike Bianchi ◽  
Paul R. Dando ◽  
Carla Morri
Keyword(s):  
Hydrothermal Vents ◽  
Aegean Sea ◽  
Bottom Layer ◽  
Food Sources ◽  
Volcanic Arc ◽  
Intermediate Disturbance ◽  
Bottom Depth ◽  
Associated Species ◽  
Water Species ◽  
Water Bottom

Research on subtidal hydrothermal vent ecosystems at Milos, Hellenic Volcanic Arc (Aegean Sea), suggested that vent activity increased the species richness of sessile epibenthic assemblages. Based on 303 species found in 6 sites (3 close to vents, 3 farther away), the present paper uses correspondence analysis and species/samples curves to examine the species composition and richness of these assemblages. Differences due to vent proximity were more important than those due to bottom depth and distance from the shore. Diversity was confirmed to be higher near the vents, although none of the 266 species found at the vent sites can be considered as obligate vent-associated species. Seven different, although not mutually exclusive, hypotheses are discussed to explain the pattern of increased epibenthic species diversity at the vent sites, namely: (i) vents represent an intermediate disturbance, inducing mortality by the emission of toxic fluids; (ii) higher winter temperature allows for the occurrence of warm-water species, which add to the regional background; (iii) venting disrupts the homogeneity of the water bottom layer, increasing bottom roughness and hence habitat heterogeneity; (iv) deposition of minerals and enhanced bioconstruction by Ca enrichment increment habitat provision; (v) fluid emission induces advective mechanisms that favour recruitment; (vi) vents emit CO2, nutrients and trace elements that enhance primary productivity; and (vii) bacterial chemosynthesis add to photosynthesis to provide a diversity of food sources for the fauna.

Serpuloidea (Annelida: Polychaeta) from Milos, an island in the Aegean Sea with submarine hydrothermalism

2000 ◽  
Vol 80 (2) ◽  
pp. 259-269 ◽  
Author(s):  
C. Nike Bianchi ◽  
Carla Morri
Keyword(s):  
Hydrothermal Vents ◽  
Aegean Sea ◽  
Western Mediterranean ◽  
Food Sources ◽  
Geographic Ranges ◽  
Larval Stages ◽  
Number Of Species ◽  
Worldwide Distribution ◽  
Species Complexes ◽  
Lessepsian Migrants

Serpuloidea were collected by diving within 45 m depth, by indirect sampling in deeper waters (50 and 81 m), and among the fouling settled on oceanographic instruments at various depths (10, 50, 80 and 83 m depth). A total of 33 species or subspecific taxa was found: 25 Serpulidae and eight Spirorbidae. All the species collected are already known for the western Mediterranean and have Atlantic–Mediterranean or worldwide distribution. Several of these, however, may be species-complexes hiding species with restricted geographic ranges. No Lessepsian migrants were found. The number of species found at vent sites was significantly higher than that found at non-vent sites, although no vent-obligate species were recognized. Hydrothermal vents might influence serpuloidean richness through four main mechanisms: (i) increasing food sources to these filter-feeders, due to the chemiosynthetic production by vent microbiota; (ii) enhancing the development of biogenic carbonate mounds, which provide habitats for encrusting and cryptic species; (iii) inducing advective mechanisms that concentrate larval stages in the vicinity of vents and thus favouring recruitment; (iv) creating, through the periodic emission of toxic fluids, a regime of `intermediate disturbance' that allows a larger number of species to coexist.

scholarly journals ASSESSMENT ON HYDROTHERMAL PARTICLE CHEMISTRY FROM A SHALLOW VENTING SYSTEM OFFSHORE KOS, AEGEAN SEA

2017 ◽  
Vol 50 (4) ◽  
pp. 1933
Author(s):  
P. Megalovasilis
Keyword(s):  
Hydrothermal Vents ◽  
Aegean Sea ◽  
East Mediterranean ◽  
Volcanic Arc ◽  
Sulphide Minerals ◽  
Membrane Filters ◽  
Ph Values ◽  
Hydrothermal Processes ◽  
Suspended Particulate ◽  
Hydrothermal Venting

Shallow submarine hydrothermal vents along Hellenic Volcanic Arc transfer significant quantities of particles enriched in basic metals. Fluids collected by scuba diving from two shallow hydrothermal venting areas on Kos Island in the Aegean Sea in East Mediterranean. Samples were filtrated and membrane filters leached with a mixture of acids. Chemical analysis performed in suspended particles for Fe, Mn, Cu, Pb, Cd, Ca, Ba, Sr, Li, Al and Si. The suspended particulate matter (SPM) flux varied from 0.93 to 8.64 mg/l and between 0.21 and 20.94 mg/l in two sites. Metal/Al ratios also vary significantly within a short distance. The pH of hydrothermal waters was from 5.50 to 5.95 in Kephalos Bay and from 6.09 to 6.53 in Bros Thermi suggesting gases CO2 and H2S may control pH values. Particles were dominated by Fe, Ca, Si and Al and strongly enriched in Mn, Cu, Pb and Ba. Three geochemical groups were identified being associated with distinct hydrothermal processes concerning sulphide minerals, carbonate substrate and deeper Al-Silicate rock basement

ANALYSIS OF ACCUMULATION AND DISTRIBUTION OF LEAD IN THE SYSTEM WATER-BOTTOM SEDIMENTS IN THE BACH DANG ESTUARY (VIETNAM)

2017 ◽  
pp. 62-66
Author(s):  
Truong Van Tuan ◽  
Irina Vladimirovna Volkova
Keyword(s):  
Bottom Sediment ◽  
Bottom Sediments ◽  
Water Samples ◽  
Suspended Solids ◽  
Natural Habitat ◽  
Bottom Layer ◽  
Sediment Samples ◽  
Natural Breeding ◽  
System Water ◽  
Water Bottom

Research was held in the estuary of the river Bach Dang (Dongbay community, Rakhtay district, Hai Phong, Vietnam) in June, 2012 - May, 2013. Concentration of lead was studied in water, suspended solids and bottom sediment. Clam beach (natural breeding environment of Meretrix lyrata ) was inspected regularly, every month. Water samples were taken 6 times from the bottom layer 10 cm down the bottom, once per 3 hours in each of 12 investigated zones. Bottom sediment samples were taken at the depth 2 cm. The findings show that lead accumulates mainly in suspended solids (23.3 mg/kg) and in bottom sediment (14.31 mg/kg), in water it is in small quantities (0.003 mg/kg). Analysis of bottom sediment samples taken in different places showed that they have even leadcontent, lead is distributed uniformly, localization of contaminations is not found. The results obtained can be assumed as the basis for investigating lead accumulation and its excretion by clam Meretrix lyrata organisms in the natural habitat.

scholarly journals Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

2012 ◽  
Vol 9 (2) ◽  
pp. 130 ◽  
Author(s):  
Vivien F. Taylor ◽  
Brian P. Jackson ◽  
Matthew R. Siegfried ◽  
Jana Navratilova ◽  
Kevin A. Francesconi ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Deep Sea ◽  
Hydrothermal Vents ◽  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Food Sources ◽  
Arsenic Compounds ◽  
Marine Animals ◽  
Δ13c And Δ15n ◽  
Organic Arsenic

Environmental contextArsenic occurs in marine organisms at high levels and in many chemical forms. A common explanation of this phenomenon is that algae play the central role in accumulating arsenic by producing arsenic-containing sugars that are then converted into simpler organic arsenic compounds found in fish and other marine animals. We show that animals in deep-sea vent ecosystems, which are uninhabited by algae, contain the same organic arsenic compounds as do pelagic animals, indicating that algae are not the only source of these compounds. AbstractArsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

Deep Structure and Active Tectonics of the South Aegean Volcanic Arc

Elements ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 153-158 ◽  
Author(s):  
Costas B. Papazachos
Keyword(s):  
Deep Structure ◽  
Active Tectonics ◽  
Aegean Sea ◽  
Low Velocity ◽  
Volcanic Arc ◽  
High Attenuation ◽  
Global Positioning ◽  
Back Arc ◽  
The Impact ◽  
Subducting Slab

The seismotectonic setting of the Aegean Sea, based on information from seismicity, neotectonics and global positioning system studies, is characterized by a sharp transition from a compressional outer arc to a complex back-arc, with an approximate north–south extension along the volcanic arc. Seismicity and 3-D tomography studies reveal the geometry of the subducting slab and image the low-velocity/high-attenuation mantle wedge at depths of 50–80 km beneath the volcanic arc where magma is generated. The 1956 Amorgos M7.5 earthquake and the impact from its seismic shaking and landslide-triggered tsunamis are discussed in the context of the regional seismotectonic setting.

scholarly journals Food sources, behaviour, and distribution of hydrothermal vent shrimps at the Mid-Atlantic Ridge

2000 ◽  
Vol 80 (3) ◽  
pp. 485-499 ◽  
Author(s):  
A.V. Gebruk ◽  
E.C. Southward ◽  
H. Kennedy ◽  
A.J. Southward
Keyword(s):  
Hydrothermal Vents ◽  
Food Sources ◽  
Larval Stages ◽  
Rimicaris Exoculata ◽  
Tube Worms ◽  
The Pacific ◽  
Mid Atlantic Ridge ◽  
Menez Gwen ◽  
Juvenile Shrimp ◽  
Supporting Structures

Five species of bresilioid shrimp were investigated at seven hydrothermal sites on the Mid-Atlantic Ridge: Menez Gwen, Lucky Strike, Rainbow, Broken Spur, TAG, Snake Pit and Logatchev. Samples were prepared for analysis of stable isotopes, elemental composition and lipids. Shrimp behaviour was observed from the submersible ‘Alvin’ and in the laboratory aboard RV ‘Atlantis’. The distribution and zonation of the shrimp species was recorded. Juvenile shrimp of all species arrive at the vents carrying reserves of photosynthetic origin, built-up in the pelagic larval stages. These reserves are used while the shrimp metamorphose to the adult form and, in Rimicaris exoculata and Chorocaris chacei, while they develop epibiotic bacteria supporting structures, the modified mouthparts and the inside of the carapace. The main food of adult R. exoculata is filamentous bacteria that grow on these structures. The intermediate sizes of C. chacei also feed on such bacteria, but the final stage gets some food by scavenging or predation. Mirocaris species scavenge diverse sources; they are not trophically dependent on either R. exoculata or mussels. Adults of Alvinocaris markensis are predators of other vent animals, including R. exoculata. The dense swarms of R. exoculata, with their exosymbionts, can be compared to endosymbiont-containing animals such as Bathymodiolus and the vestimentiferan tube-worms of the Pacific vents. Such associations, whether endo- or ectosymbiotic, may be necessary for the development of flourishing communities at hydrothermal vents.

scholarly journals Trophodynamics at the Longqi hydrothermal vent field and comparison with the East Scotia and Central Indian Ridges

2020 ◽  
Vol 167 (10) ◽  
Author(s):  
W. D. K. Reid ◽  
B. D. Wigham ◽  
L. Marsh ◽  
J. N. J. Weston ◽  
Y. Zhu ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Hydrothermal Vent ◽  
Hydrothermal Vents ◽  
Trophic Ecology ◽  
Tricarboxylic Acid Cycle ◽  
Isotope Analysis ◽  
Southwest Indian Ridge ◽  
Food Sources ◽  
Model Based Clustering ◽  
Indian Ridge

Abstract The Longqi vent field, situated on the Southwest Indian Ridge, is ecologically distinct among known hydrothermal vents fields. It hosts a combination of previously unknown species and those shared at species or genus level with other hydrothermal vents on the Central Indian Ridge (CIR) and East Scotia Ridge (ESR). We investigate the size-based and trophodynamics of consumers at Longqi vent field and compared these with ESR and CIR vent fields using stable isotope analysis. Intra-specific variability in δ13C and δ15N values in relationship to shell length was observed in Gigantopelta aegis but absent in Chrysomallon squamiferum. A model-based clustering approach identified four trophic groupings at Longqi: species with the lowest δ13C values being supported by carbon fixed via the Calvin–Benson–Bassham cycle, the highest δ13C values being supported by the reductive tricarboxylic acid cycle and intermediate values potentially supported by a mix of these primary production sources. These clusters were driven by potential differences in resource partitioning. There were also differences in the spread of stable isotope values at the vent field level when comparing Bayesian stable isotope ellipse areas among Longqi, CIR and ESR vent fields. This was driven by a combination of the range in δ13C value of macrofauna, and the negative δ15N values which were only observed at Longqi and CIR vent fields. Many of the shared species or genera showed inter-vent field differences in stable isotope values which may be related to site-specific differences in food sources, geochemistry or potential intra-field competition. This study provides important information on the trophic ecology of hydrothermal vent macrofauna found within an area of seabed that is licensed for seabed mining exploration.

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