DEAD MEN STILL TELL TALES: MOLLUSCAN DEATH ASSEMBLAGES RECORD A BOOM-BUST INVASION AND A CHANGING COMMUNITY IN KINGSTON HARBOUR, JAMAICA

The Indo-Pacific green-lipped mussel (Perna viridis) was first observed in the Kingston Harbour in 1998, likely introduced through contaminated ballast water. The species quickly overtook mangrove roots, wharf pilings, and pier walls as it outcompeted native species. However, the population has declined within the last decade, to the point of absence in some previously overrun areas. The full scope of the invasion, as well as potential impacts on native species, are therefore difficult to further elucidate with reference to only the living community.

The goals for this study were to 1) compare dead shell abundances to densities reported during peak invasion, and 2) assess live-dead discordance for the entire bivalve community. We surveyed bivalves attached to mangrove prop roots and wharf pilings and collected death assemblages from bulk sediment samples surrounding Port Royal on the south side of the harbor. Perna viridis shells were present and abundant in most dead samples. Ranked dead shell abundances also mirrored that of live specimens reported from previous surveys. However, the proportions of the three most abundant native species (Crassostrea rhizhophorae, Isognomon alatus, and Brachidontes exustus) always exceeded P. viridis, likely due to considerably longer accumulation and time averaging. These three species make up the bulk of the live community, although their relative abundances differ from those of the dead. Further, the previously undocumented charru mussel (Mytella charruana) appears to have invaded the harbor within the last decade, an opportunity possibly created by the decline of P. viridis.

Although death assemblages are widely used for defining baselines that predate modern communities, these findings demonstrate their ability to also capture rapid, sub-decadal ecological events that help explain live-dead discordance patterns.