Fouling and gastropod predation: consequences of grazing for a tropical octocoral

Abstract

The ovulid gastropod Cyphoma gibbosum Linnaeus is a specialist consumer of gorgonian octocorals. Although the direct effects of its feeding do not appear to be great, the indirect consequences may be substantial. An 8 wk study of the gorgonian Plexaura hornornalla Esper in Curaqao found that C. g~bbosum occurred primarily on the lower 30 cm of colonies, and that there were significant correlations between C glbbosum density and the extent of colony fouling on the lower 30 cm of colonies. This correlation occurred whether one measured in~tial fouling, final fouhng, or change in fouling during the 8 wk. There were no significant correlations of C. gibbosum density and fouling for colony portions more than 30 cm above the holdfast. These findings and direct observations in the field suggest that feeding by C. gibbosum increases fouling of gorgonians by exposing the axial skeleton and providing settling sites for fouling propagules. Because fecundity of P. homornalla is reduced when fouhng separates colonies into a series of smaller aggregates, the indirect effects of C. g~b b o s u m grazing could strongly affect the fitness of P. hornornalla and other gorgonians.

Predator release of the gastropod Cyphoma gibbosum increases predation on gorgonian corals

“…Cyphoma gibbosum could be observed feeding on gorgonians and were often at or near areas completely stripped of all tissue. The damage on gorgonians was consistent with previous descriptions of C. gibbosum feeding (Harvell and Suchanek 1987;Gerhart 1990) and inconsistent with damage done by Hermodice carunculata (Vreeland and Lasker 1989) which was infrequently observed inside the caged areas and rarely observed on gorgonians. Most grazing removed all soft tissue from the grazing scar and exposed the gorgonian skeleton, even for species that have thick coenenchyme such as Eunicea spp.…”

“…Further, our estimates of C. gibbosum damage to gorgonians are conservative in that we quantified only recent damage (i.e., feeding scars not yet overgrown with fouling organisms). Fouling of the exposed gorgonian skeleton following C. gibbosum predation is common, happens within only a few weeks (Gerhart 1990), and would have appreciably increased the estimates of C. gibbosum grazing had such damage been included.…”

“…We did not include areas of exposed gorgonian skeleton that had been fouled by epiphytic algae or invertebrates, despite these being extensive on several gorgonians in the caged areas. Although this damage probably resulted from previous C. gibbosum grazing (Gerhart 1990), it could not be unambiguously attributed to predation by C. gibbosum and so was not included in our analyses. We also excluded gorgonians that were within 10 cm of the cage because these could have been damaged by wave action abrading them against the cage.…”

Widespread disease in Caribbean sea fans:II. Patterns of infection and tissue loss

“…Tissue predation by this snail can expose the internal skeleton of the sea fan and can thus facilitate colonization by fouling organisms (Wahle 1985, Gerhart 1990 as well as pathogens. However, Smith et al…”

Coat of many colours—DNA reveals polymorphism of mantle patterns and colouration in CaribbeanCyphomaRöding, 1798 (Gastropoda, Ovulidae)

“…It is therefore often used as a model organism and has been used in studies dealing with allelochemicals and physical defence systems (Van Alstyne & Paul, 1992; Vrolijk & Targett, 1992; Whalen et al, 2010), studies on their association with fungal diseases in Caribbean gorgonians (Rypien & Baker, 2009) and research on reef degradation and predation (Gerhart, 1990; Burkepile & Hay, 2007; Evans, Coffroth & Lasker, 2013). The genus Cyphoma has 14 extant species recognised by Lorenz & Fehse (2009) and 13–15 extant species according to Rosenberg (2015).…”