The distribution of some plankton animals in the English Channel and approaches: ii. Surveys with the Gulf iii high-speed sampler, 1958-60

Abstract

SUMMARY: Comparison of the recent surveys with investigations back to 1903 confirms earlier suggestions of a general tendency towards an increase in southern forms (including south-western species) and a decrease in northern forms (including north-western species) in the western English Channel, although there has been considerable fluctuation from time to time. These and other biological changes in the area during the past 58 years are believed to be largely a result of rising temperatures and a consequent general shifting of boundaries of distribution. There appears to be no real evidence that the changes in plankton distribution are due to a change in fertility in the water or of variation in strength of inflow of oceanic water. However, these aspects cannot be separated from the changes that have taken place in populations of fish, and will be discussed further in a later paper.