The influence of the composition of algal detritus on nematode assemblages

A field-based experiment was conducted on a detritus-loaded beach from the south coast of the British Isles (Poole Harbour) to investigate the decay rates of different combinations of algal detritus and their associated nematode assemblages. Ten algal mixture treatment combinations (monocultures with all possible 2 or 3 mixed algal treatments) of three different species of green (Chlorophyta), brown (Phaeophyta), and red (Rhodophyta) algae were used to determine how the diversity of decaying algal detritus affects the associated nematode assemblage composition and structure. Our results indicated that nematode density, diversity, and assemblage composition differed significantly among the different algal treatments. The nematode densities and genera richness were significantly higher in the mixed algal treatments compared to those in the algal monoculture treatments. The loss of seaweed dry weight varied significantly among the algal detritus treatments with which included brown algae tending to decay at a slower rate than others. These results indicate different type of macroalgae detritus could offer different nutrient input and that encourage different dominant nematode species and composition. •A comprehensive in situ experiment revealed a role of algal detritus on nematode assemblages.•Breakdown rates greatly varied among the algal detritus treatments with typical/specific alga.•Nematode density, diversity, and composition differed significantly among algal treatments.•Brown algae tending to decay more slowly than others, offering lesser favourable food quality.•Nematodes prevailed in mixture treatments than single algae, reflecting nutritional effect.