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

Abstract

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 submersibleÀlvin'and in the laboratory aboard RVÀtlantis'. 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 modi¢ed mouthparts and the inside of the carapace. The main food of adult R. exoculata is ¢lamentous bacteria that grow on these structures. The intermediate sizes of C. chacei also feed on such bacteria, but the ¢nal 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 Paci¢c vents. Such associations, whether endo-or ectosymbiotic, may be necessary for the development of £ourishing communities at hydrothermal vents.

Inorganic carbon fixation by chemosynthetic ectosymbionts and nutritional transfers to the hydrothermal vent host-shrimp Rimicaris exoculata

“…Others, arguing that the cuticle is impermeable, reject this hypothesis (Segonzac et al, 1993;Gebruk et al, 2000). The latter authors refer to an experiment (Anderson and Stephens, 1969) or to subsequent review papers (Stephens, 1988;Preston, 1993;Gebruk et al, 2000) suggesting that crustaceans, in contrast to many other marine invertebrates, cannot take up dissolved organic matter or dissolved organic carbon. According to Anderson and Stephens (1969), the apparent incorporation of radiotracers by crustaceans was due to uptake by epibionts alone and not by the crustaceans themselves.…”

Assessment of decadal-scale ecological change at a deep Mid-Atlantic hydrothermal vent and reproductive time-series in the shrimp Rimicaris exoculata

“…The shrimp derive nutrition from epibiotic bacteria (Van Dover et al, 1988;Gebruk et al, 2000), though iron-oxidising bacteria inhabit the gut of the shrimp and may also play a role in their nutrition.…”

“…Dives took place in July-September 1994, March 1995 (Copley et al, 1999), July 1997 (Gebruk et al, 2000), August 1998 (Chiba et al, 2001) (Lutz et al, 2002). The per-watt light output of HMI lights (~100 lumens per watt) is typically five times that of tungsten-halogen lighting and has the same colour temperature as sunlight (5600 K).…”

“…Undescribed chaetopterid polychaetes are also present on the periphery of the mound, in the zone most remote from active vents (Galkin, 2002). The substratum of the mound varies from exposed anhydrite and fresh sulphides at the central black smokers to oxidised sulphide rubble and regions of ponded hydrothermal sediments in the periphery.Rimicaris exoculata is known at hydrothermal vents on the Mid-Atlantic Ridge from the Lucky Strike vent field southwards, often present in high-density aggregations (>1500 individuals m -2 ) around high-temperature vents at deeper sites (Van Dover et al 1988, Copley et al 1997Gebruk et al, 1997;Gebruk et al, 2000). The shrimp derive nutrition from epibiotic bacteria (Van Dover et al, 1988;Gebruk et al, 2000), though iron-oxidising bacteria inhabit the gut of the shrimp and may also play a role in their nutrition.…”

Small-scale distribution of deep-sea demersal nekton and other megafauna in the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge

“…Submersibles have extended the range at which we can directly observe the natural history of deep-sea organisms, in particular their behavior (e.g., Cohen, 1977;Drazen et al, 2003;Uiblein et al, 2003) and small-scale distribution (e.g., Grassle et al, 1975;Smith and Hamilton, 1983;Kaufmann et al, 1989) when investigating deep-sea regions of rough topography such as ridges and volcanic island slopes (e.g.. Chave and Malahoff, 1998), hydrothermal vents (Gebruk et al, 2000) and in the open ocean (Vinogradov, 2005). Interactions of deep-sea organisms with their environment can be documented from videotapes taken from submersibles as well as by direct observations (Felley and Vecchione, 1994;Levin et al, 1994), providing insight into the environmental variables that affect the distribution of these forms.…”