Untangling the effects of size, habitat and invertebrate biodiversity on parasite prevalence in the Caribbean spiny lobster

Abstract

The spiny lobster Panulirus argus is an important benthic mesopredator and a major fishing resource across the Wider Caribbean region. This species is host to the pathogenic virus PaV1 and metacercariae of Cymatocarpus solearis, a digenean trematode whose first intermediate host remains unknown. Previous studies found that the probability of infection with PaV1 was higher in juvenile lobsters and in densely vegetated habitats (suggesting that marine vegetation can be an environmental reservoir for PaV1), whereas the probability of infection with C. solearis was higher for larger lobsters and in poorly vegetated habitats. To increase insight into the role of habitat and body size in the ecology of lobster diseases, the presence of both C. solearis and PaV1 in P. argus was investigated across three contrasting zones in Bahía de la Ascensión, Mexico (19°35′27″N, 87°38′06″W): reef, lagoon and shallow habitat. Additionally, habitat complexity, cover of benthic components, and macroinvertebrate biodiversity were characterized in each zone. Consistent with previous studies, probability of infection with PaV1 (both at a clinical and infective level) decreased with increasing lobster size and was highest in the seagrass-rich lagoon, supporting the idea that marine vegetation could be an environmental reservoir for PaV1. In contrast, the probability of infection with C. solearis increased significantly with lobster size but did not vary with zone, suggesting no relationship with benthic substrate type. However, based on results of macroinvertebrate diversity, the gastropods Cerithium litteratum and Tegula fasciata are put forward as potential candidates for the first intermediate hosts of C. solearis.

Do ecological characteristics drive the prevalence of Panulirus argus virus 1 (PaV1) in juvenile Caribbean spiny lobsters in a tropical reef lagoon?

“…As previously noted, some studies have reported a higher PaV1 prevalence in densely-vegetated areas compared to poorly-vegetated areas even after accounting for the significant effect of lobster size, suggesting that vegetation may be acting as an environmental reservoir for the disease [14,15]. This notion has been supported by a recent study [16] in which the probability of infection with PaV1 was found to be higher in lobsters inhabiting more vegetated habitats, but further proposing that either marine vegetation or fauna that live associated with vegetated habitats, or both, may be reservoirs of PaV1.…”

“…To examine potential ecological differences among sampling zones and over time, percent cover of different types of substrate, habitat complexity, and invertebrate diversity were estimated in each zone [16] for two contrasting seasons (June and November) over two years (2016 and 2017), yielding four sampling periods. In each period, six transects, each 25 m in length, were laid parallel to the reef and the coast in each zone.…”

“…In each period, six transects, each 25 m in length, were laid parallel to the reef and the coast in each zone. Each transect was marked every 50 cm [16]. The percentage of cover of the following types of substrate was estimated using the point intercept method: seagrasses, macroalgae, sand, rubble, live hard corals, soft corals, hard bottom, and sponges [41].…”

“…PaV1 only affects P. argus and is currently widespread throughout the Caribbean [10,11], linked to various factors. Principally, PaV1 prevalence has been correlated with lobster size, being found more in smaller, juvenile lobsters [12,13], and with habitat, being found more in highly-vegetated habitats [14][15][16], suggesting that vegetation may be acting as an environmental reservoir for the virus.…”

“…However, small-scale habitat characteristics (e.g. habitat complexity, types of substrate) and species diversity of local communities can play important roles in disease ecology [16,21,23,24]. This may be of more concern for juvenile lobsters than for adult lobsters because juveniles, especially those <50 mm CL, have far more limited movement ranges than adults [2,26,27] and are more susceptible to PaV1 [9,12,15].…”