ABSTRACT:

Parasitic micro-organisms can influence multiple ecological processes, from growth, mortality, and behavior, to community structure and trophic interactions, yet are typically ignored components of marine biodiversity. We collected 1298 blood samples from reef fishes off 6 eastern Caribbean islands, representing 27 families, 57 genera and 103 species, including invasive Indo-Pacific lionfish. Members of 14 species from 8 families were infected, comprising damselfishes (Pomacentridae), parrotfishes (Scaridae), mullet (Mugilidae), jacks (Caranjidae), Blennies (Blenneidae and Labrisomidae), snappers (Lutjanidae), and angelfishes (Pomacanthidae). None of the 8 distinct blood parasites found fit descriptions of other Caribbean parasites, but resembled typical Haemogregarina-like intraerythrocytic parasites and Haemohormidium-like parasites collected from fishes on the Great Barrier Reef (GBR), Australia. No blood parasites were found in lionfish and there was surprisingly little overlap in the families of Caribbean and GBR fishes. Most infected species were strongly diurnal. The high incidence of infection in Stegastes damselfishes was particularly surprising and has potentially important ecological consequences, given that damselfishes influence benthic community structure and are prey for reef piscivores. Gnathiid isopods, an apparent vector of apicomplexan blood parasites in other systems, were common at sampling sites and collected for use in transmission experiments. Haemogregarina-like parasites were taken up by gnathiids that fed on infected blennies. By comparison, when gnathiids fed on Stegastes damselfish infected with a Haemohormidium-like parasite, no parasites were found. This study reveals the high biodiversity of haemoparasites infecting eastern Caribbean reef fishes, and highlights the need for additional research throughout the Caribbean and in other tropical reef systems.