Biodiversity at mid-ocean ridges, and other topics
Biodiversity at mid-ocean ridges is a topic of interest to us and our colleagues. Check the list of our collaborators' publications, and stay tuned for more. Among other things, we are working to assess population changes on recent lava flows and on aging hydrothermal chimneys.
Some of the animals we find at ridges are similar or the same as we find elsewhere, for example the Acesta clams from the Alarcon Rise and Gulf of California profiled here were examined at seamounts in the Northeastern Pacific.
Acesta clam on one of the California seamounts
Image © MBARI 2000
Our research on eclectic topics at ridges
Range and depth extension of Acesta clams
GULF OF CALIFORNIA - Two species of limid clams, Acesta sphoni and Acesta mori, were observed and sampled from seven localities in the Gulf of California, Mexico. The two species are known to occur on seamounts and escarpments along the north-eastern Pacific margin of the United States. This report provides the first records of each species in the Gulf of California and the greatest depth records for both species. Though they occasionally overlap geographically, the two species are clearly stratified by depth, with A. sphoni occupying shallower and warmer, hypoxic waters, and A. mori occupying deeper and colder, oxic waters. The species are easily distinguished morphologically. The shells of A. mori have very fine radial ribbing for a smooth appearance and are more rounded and inflated, whereas those of A. sphoni are narrower and more elongate with 31 to 77 strong radial ribs. The largest individuals sampled were A. sphoni. For each species, DNA analyses revealed arrays of mitochondrial haplotypes similar to those found previously at north-eastern Pacific localities along the California, Oregon and Washington margins, providing no evidence for geographical subdivision throughout this newly extended range.
Reference: Walz, K.R., D.A. Clague, J.P. Barry, and R.C. Vrijenhoek (2014) First records and range extensions for two Acesta clam species (Bivalvia: Limidae) in the Gulf of California, Mexico. Marine Biodiversity Records, 7: 6 pp. doi: 10.1017/S1755267214000165.
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