Attraction to decaying organisms as a possible cause for patchy distribution of nematodes in a Bermuda beach

Abstract

At Tucker's Town Cove, Bermuda, seven 50-ml samples of washed sand, four of them baited with a 5 cm piece of frozen sardine, were buried in the beach sediment at different distances from high tide mark and recovered after 1-11 days. They were compared with 12 control samples (10 ml each) of undisturbed sand from the same area. After 4-7 days of exposure the mean abundance of nematodes in both groups of experimental samples was about as high as in the control samples. Three of the four most abundant nematode species in the area were especially attracted to the experimental samples. Comesoma bermudense (Comesomatidae) and Nannolaimoides decoratus (Cyatholaimidae) were equally attracted to baited and unbaited samples, while Sabatieria migrans (Comesomatidae) was more attracted to the decaying fish in the baited ones. Sabatieria migrans showed a patchy distribution in the control samples and this may be caused by its attraction to decaying organic matter or the associated microflora. Comesoma bermudense, however, showed a uniform distribution in the control samples, while Nannolaimoides decoratus showed a patchy distribution. Similar experiments at Niva Bay (Danish coast of the Øresund) did not produce comparable results. The possible reasons for this are discussed. Data are provided for the nematode faunas of the intertidal protected beach at Tucker's Town Cove, Bermuda, and of the ‘sulphuretum’ of Nivå Bay.