SEASONAL-CHANGES IN STRUCTURE OF AN ALASKAN INTERTIDAL MEIOFAUNAL ASSEMBLAGE

A subarctic, intertidal meiofaunal assemblage in Auke Bay, Alaska, USA , was sampled throughout one year at 3 intertidal heights; mean low wa ter (0 m) and 1 m above and below this level (+1 m, -1 m). Samples wer e taken twice a month at 0 m and approximately every other month at -1 and +1 m intertidal heights. Nematodes predominated numerically (31 t o 77%), followed by harpacticoid copepods (adults and copepodites comb ined 10 to 35%, nauplii 5 to 32%). Meiofaunal densities fluctuated sig nificantly throughout the sampling period. The demography of the 6 num erically predominant species of copepods was examined. In order of abu ndance, they were Halectinosoma sp., Amphiascoides dimorphus Lang 1965 , Microarthridion cf. littorale Poppe 1881, Apolethon sp., Mesochra sp . and Stenhelia (Stenhelia) peniculata Lang 1965. Densities of the adu lts, ovigerous females and copepodites of these species changed signif icantly throughout time. The peak densities of ovigerous females and c opepodites were well separated temporally (whereas those of adults ove rlapped) and tended to occur in months from November to March. Only M. cf. littorale displayed a high abundance of ovigerous females and cop epodites in the summer months. Reproductive patterns varied among the harpacticoid species, from discrete (Apolethon sp.) to continuous repr oductive periodicity (all other species).