The distribution of hyperiid amphipods off the Oregon coast

• Main Author: Van Arsdale, Harriet Ann
• Other Authors: Pearcy, William G., Oceanography, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Plankton > Oregon; Subarctic
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/w37639753

Hyperiid amphipods from one-meter plankton net collections made over a two year period at stations 15, 25, 50, and 65 nautical miles off Newport, Oregon, were examined. Nineteen species were identified. The occurrence of some species off Oregon significantly extended the known geographic ranges. To my knowledge Scina crassicornis burmudensis and Tryphana malmi have not been previously recorded in the North Pacific. Streetsia challengeri, Hyperia hystrix, Lycaea pulex, Oxycephalus clausi, Cystisoma fabricii, and Lanceola loveni have not been reported north of California in the eastern Pacific. The frequency of occurrence of Parathemisto pacifica, Paraphronima gracilis, Hyperia hystrix, Tryphana malmi, and Primno abyssalis generally increased with distance from shore. Average abundance of these species was usually maximal 50 miles offshore and decreased inshore and farther offshore. Inshore, the largest total catches of hyperiids occurred during the winter, a period when the movement of water was onshore and the heat content was relatively high. Lowest catches and lowest species diversity were found inshore during the summer when upwelling caused offshore movement of surface water. Amphipod catches were compared to the proportion of Subarctic water present, but no consistent relationship was apparent. Vertical distributions of common species were examined. Although catches sometimes varied with depth, evidence for vertical migration was inconclusive.