Feeding Habits and Diet of the Midwater Polychaete Poeobius meseres (Heath 1930) in Monterey Bay, California

摘要

This study presents the first quantitative and temporal information regarding the feeding habits and diet of a gelatinous midwater organism. With the Monterey Bay Aquarium Research Institute's (MBARI) remotely operated vehicle (ROV), Ventana, regular collections of the midwater polychaete, Poeobius meseres (Heath 1930), Monterey Bay, California were made from October 1990 to November 1991. Seventy P. meseres were collected into one to five 2 1 canisters, with a variable speed suction sampler mounted on the ROV. All collections were between 260-480 m. Simultaneous realtime observations with a high resolution Sony DXC 3000 video camera, mounted on the ROV during all collections, were undertaken. Upon retrieval of the ROV, specimens were fixed in 5% formalin for stomach content analysis and 2% glutaraldehyde for scanning electron microscopy (SEM). Observations of head morphology were made on preserved specimens with SEM to gain insight into the way P. meseres feeds. The head with palps and cirri was carefully excised with a scapel at the beginning of the digestive tract, dehydrated in a graded ethanol series (70-100%), soaked in 100% ethanol, postfixed in osmium tetroxide, critical-point dried in carbon dioxide, coated with gold, and photomicrographed with an ISI # WB- 6 SEM. Entire visible surfaces of the cephalic region, including palps and cirri, were photographed (Figs. 1, 2). SEM was also conducted on stomach contents to characterize further the food items ingested by P. meseres. Stomach contents of specimens fixed in 5% formalin were placed in filtered seawater and drawn onto 0.2 mm nuclepore membrane filters, washed with distilled water, and air dried. Filters were mounted onto stubs with double-sided tape, sputter coated with gold palladium, and photomicrographed for identification.