Correlation of benthic Mollusca with substrate composition in lower Galveston Bay, Texas.




Harry, H.W.

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Only 22 of 69 spp. of mollusks were found alive at 41 stations along 2 subtidal transects (in Texas, USA): 42 bivalves, 26 gastropods, 1 scaphopod. Two oyster reefs and an ancient beach were included in the otherwise mud bottom. Five species of presumed fossils were present in the submerged beach. The average number of species (alive and dead) increased directly with the percent sand-shell. The average number of live specimens was greater within than beyond the range of 25-75% sand-shell. The shells of each species apparently have an intrinsic durability which may vary in different environments, particularly as substrate composition varies. Twelve species, all bivalves, are cited as the more durable in this area. Five methods of transport are suggested to account for 17 adventitious species, 6 as living juveniles or rare adults, all from adjacent habitats. Live specimens in marine benthic samples do not necessarily indicate established, reproducing populations of their species.


p. 135-152.


marine molluscs, substrate preferences, bivalves, gastropods, scaphopods, ecological distribution