Meeting Abstract
The formation of symbiotic relationships is a most common adaptation among marine crustaceans forming both obligatory and non-obligatory (facultative) dependencies with their host. How the obligatory nature of these symbioses influences the invertebrates population structure has only been mildly addressed in the literature. Here we investigate and compare the population structure of an obligate symbiont (Ceratoconcha domingensis; a barnacle) and a facultative symbiont (Laophontella sp.; a harpacticoid copepod) of the coral Agaricia lamarcki from shallow and mesophotic habitats. Barnacle specimens were collected from shallow (<30 m) and deep (>30 m) colonies of A. lamarcki in La Parguera and Guanica¸ Puerto Rico. Laophontella sp. was collected from mesophotic (>50 m) A. lamarcki colonies in El Seco, Vieques and mangrove sediments (<3 m) in Curacao. The Cytochrome Oxidase Subunit I gene was amplified and sequenced for barnacle (n=93) and copepod (n=54) specimens. Molecular analysis revealed no population structure between deep and shallow barnacle populations within La Parguera and Guánica (ΦST = 0.00444). Meanwhile, Laophtontella sp. was shown to have significant structure between the mesophotic reef of El Seco and mangrove sediments of Curacao (ΦST = 0.28). Interestingly, the El Seco and Curacao sample sets had three shared haplotypes. Shared haplotypes were unexpected between these sample localities based on the general life history of harpacticoid copepods and the geographic distance between locations. Four outlier sequences were identified within El Seco sequences potentially representing three different species. The identification of potentially three cryptic species is proof of the current need for a deeper investigation into the meiofaunal diversity associated with mesophotic ecosystems.
