Published online by Cambridge University Press: 05 December 2011
An account is given of the benthic harpacticoid copepods of a medium grade subtidal sand at a depth of 8–5 m (below chart datum) off the Ayrshire coast at Hunterston. It is the first account of seasonal changes in subtidal harpacticoids in the Firth of Clyde.
Most of the population is restricted to the top 1 cm layer of sand and this is considered to be related to food availability. There were considerable variations in total densities with largest numbers occurring in late June, as seawater temperatures increased rapidly towards the summer maxima.
Two species examined in detail, Asellopsis hispida and Harpacticus flexus each had one distinct period of reproduction during the year. Gravid females appeared first during the coldest months (January and February) followed by large numbers of copepodites from late April to June, culminating in large numbers of adults in June. Adult males clasped female stages only in May and June, after the main period of egg production. It is thought that viable sperm is carried by the adult females for about six to seven months, supposedly until the next period of egg production the following year. Adults of Harpacticus flexus are thought to be an important source of food for juvenile and small fish, particularly during July.