The copepods in a collection from the southern coast of Oregon, 1963

• Main Author: Lee, Wen-yuh
• Other Authors: McCauley, James E., Oceanography, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Copepoda; Pseudocalanus minutus; Copepods
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/6d56zz70p

Plankton samples for this present study were collected from an area off the southern Oregon coast, extending westward to about 83 kilometers offshore. Over this sampling area, 41 species of adult copepods were identified, including representatives of 26 genera and 17 families. The total abundance averaged 550/m³. Population densities of copepods as a group were found higher inshore than offshore and this distribution was largely determined by four dominant species, that is, Oithona similis, Pseudocalanus minutus, Acartia longiremis, and Acartia clausi. They accounted for approximately 81% of the total copepod abundance. Species diversity had a tendency to increase with distance from the coast. This could be due to the possibilities that the sampling depth was increased offshore, or that the living environment was more stable offshore than inshore. Rank-correlation analysis of the four dominant species, fish eggs, copepod nauplii, euphausiids, and Eucalanus bungii suggest that the positively correlated category includes several pairs, Oithona similis to Pseudocalanus minutus, O. sirnilis to Acartia clausi, A. longiremis to P. minutus, fish eggs to O. similis, A. longiremis to A. clausi, O. similis to copepod nauplii, and fish eggs to copepod nauplii. The negatively correlated category includes three pairs, euphausiids to copepod nauplii, euphausiids to fish eggs, and euphaus lids to O. similis. Results from the correlation analysis of the dominant species relative to temperature, salinity, and distance from shore show that no significant relationship was apparent except that the occurrence of P. minutus was negatively correlated to distance from shore.