Effect of infestation by a nemertean egg predator on female Caribbean spiny lobster reproductive performance in the Florida Keys, USA

The heightened prevalence and intensity of a recently discovered nemertean egg predator, Carcinonemertes conanobrieni , in Caribbean spiny lobster Panulirus argus embryo masses poses a rising threat to this commercially and recreationally important decapod crustacean. The goal of our study was to assess the prevalence and effect of C. conanobrieni on female P. argus reproductive performance. Ovigerous lobsters were collected across the Florida Keys reef tract (USA) and examined for infestation by C. conanobrieni . Reproductive performance was determined as the reproductive output (%) and fecundity (no. of eggs per female) of all lobsters. We used redundancy analyses to identify which host traits explain variation in the intensities of C. conanobrieni life stages within a female’s brood mass and to determine the effect of C. conanobrieni on lobster reproductive performance. We observed 100% prevalence of C. conanobrieni among brooding P. argus over 2 consecutive years (2022, 2023). Reproductive performance was lower and embryo mortality (%) higher among lobsters carrying late-stage embryos compared to those with early-stage embryos. Lobsters carrying early-stage embryos also appeared to be infested primarily with juvenile C. conanobrieni , while those carrying late-stage embryos had mainly C. conanobrieni adults and egg masses present. Declines in overall reproductive performance of P. argus could be attributable to C. conanobrieni based on our findings, especially given that the life cycle of this egg predator aligns closely with the cycle of P. argus embryo development. C. conanobrieni outbreaks might impact fisheries targeting P. argus across its Caribbean distribution; thus, heightened surveillance for this nemertean is important.