Jtp. Copley et al., SPATIAL AND INTERANNUAL VARIATION IN THE FAUNAL DISTRIBUTION AT BROKEN-SPUR VENT FIELD (29-DEGREES-N, MID-ATLANTIC RIDGE), Marine Biology, 129(4), 1997, pp. 723-733
Initial ecological observations at Broken Spur in 1993 suggested a low
biomass relative to other deep-water vent communities known along the
Mid-Atlantic Ridge. The persistence of a low shrimp biomass over 15 m
o at Broken Spur vents appears to refute the hypothesis that the commu
nity is expanding through reproduction and immigration to occupy habit
at vacated during a recent period of hydrothermal quiescence or catast
rophe. Although the absence of ''swarms'' of shrimp similar to those f
ound at the hydrothermal mounds of TAG (26 degrees N) and Snake Pit (2
3 degrees N) is a visually striking feature of the majority of venting
structures known at Broken Spur, the biomass of fauna other than shri
mp may not be significantly less than that of other Mid-Atlantic sites
. The discovery of ''swarms'' of shrimp at Bogdanov Site, visited for
the first time in 1994, suggests that availability of substratum expos
ed to the flow of hydrothermal fluids, which is a function of the topo
graphy of venting structures, may be a prerequisite for the developmen
t of these dense aggregations. Two testable predictions arise from thi
s hypothesis. Firstly, dense aggregations of Rimicaris exoculata shoul
d occur at any other structures with a morphology similar to Bogdanov
Site that may be discovered in the Broken Spur vent field, and should
not occur at other isolated chimney structures that may be found. Seco
ndly, ''swarms'' of shrimp should appear at any Broken Spur chimneys t
hat develop into structures with a morphology more similar to that of
Bogdanov Site in future.