Infection with cerebral metacercariae of microphallid trematode parasites reduces reproductive output in the gammarid amphipodGammarus insensibilis(Stock 1966) in UK saline lagoons

Abstract

Saline lagoons are priority habitats in the United Kingdom supporting several protected specialist species. One specialist, the amphipodGammarus insensibilis, is infected with behaviour-altering microphallid trematodes such asMicrophallus papillorobustus. In saline lagoons around the coast of England (Gilkicker and Lymington–Keyhaven on the Hampshire coast and Moulton Marsh in Lincolnshire) there is variation in the prevalence of this parasite in the gammarid populations (0 at Salterns in the Lymington–Keyhaven lagoon system to 98% at Gilkicker). Infection intensity ranged from 0 to 20 metacercariae in individual amphipods. Higher infection intensity can alter the shape of the amphipod's head. Under experimental conditions respiration rate is significantly reduced in infected animals and reproductive output (expressed as early stage embryos mg g dry weight−1) is significantly lower in infected females. It is important to consider the role of host–parasite interactions in order to understand the ecology of specialist lagoon species such asG. insensibilisand their lagoon habitats.