The deepwater mud-bottom community identified previously as one of three benthic infauna communities off the coast of Washington was found at mean depths of 154.5 m in sediments with a mean mud percentage of 50.09%. The most abundant species were the polychaetes Prionospio malmgreni, Sternaspis fossor, and Ninoë gemmea, the lamellibranchs Axinopsida serricata, Adontorhina cyclia, and Macoma carlottensis, and the amphipod Heterophoxus oculatus. The mean standing crop (ash-free dry weight) was 3.058 g/m2, with the echinoderms Brisaster latifrons, Ophiura lütkeni, and Amphioplus sp. and the polychaete Sternaspis fossor as the major contributors to the standing crop.The intermediate depth sand-bottom community was found at stations with a mean depth of 95.8 m in sediments with a mean sand percentage of 67.81%. The most abundant species were the polychaetes Magelona sp., Sternaspis fossor, Nephthys sp., and Haploscoloplos elongatus, the lamellibranchs Yoldia ensifera and Axinopsida serricata, and the amphipod Paraphoxus variatus. The mean standing crop was 2.533 g/m2, with the species listed above and the lamellibranch Macoma elimata as the major contributors to the standing crop.The shallow water sand-bottom community was found at stations with a mean depth of 36.0 m in sediments with a mean sand percentage of 96.33%. The most abundant species were the cumacean Diastylopsis dawsoni, the amphipods Ampelisca macrocephala and Paraphoxus obtusidens, the lamellibranchs Tellina salmonea and Macoma expansa, and the polychaete Owenia fusiformis. The mean standing crop was 1.398 g/m2, with the species listed above and the polychaetes Nephthys sp. and Chaetozone setosa and the lamellibranch Siliqua patula as the major contributors to the standing crop.There was a distinctly lower species diversity in the shallow water sand-bottom community than in the two communities in deeper waters.
Features of spatial distribution of benthic infauna in a Mediterranean shallow-water bay
