Cryptofauna associated with rhodoliths: Diversity is species‐specific and influenced by habitat

Abstract

AbstractRhodoliths are recognised as providing critical ecosystem services in nearshore systems through habitat provision. We tested the influence of rhodolith hosts and habitat on the diversity and composition of sessile and motile invertebrates found associated with two species of rhodolith. Investigations of cryptofauna were undertaken at three beds within the Bay of Islands, northern New Zealand. Lithothamnion crispatum, which was smaller in overall size, and had less free space and a smaller internal volume than Sporolithon sp., provided habitat for more species of distinct life forms, both motile and sessile species, than Sporolithon sp. Although there were few differences in the dimensions of L. crispatum found in the beds, there was significantly more free space available in Sporolithon sp. rhodoliths found in one of two beds where it occurred, and the associated cryptofaunal richness of both sessile and motile species was significantly higher in this population. This study revealed species‐specific differences in the rhodolith‐associated cryptofauna and a significant impact of rhodolith habitat on growth form and cryptofaunal assemblages at the sites investigated in one of the host species (Sporolithon sp.). Understanding interactions between species and habitats provided by rhodoliths is critical to understanding the nature of ecosystem services provided in these biogenic habitats.