Bearded fireworm

Abstract: The amphinomid fireworm Hermodice carunculata is a potentially invasive species reported throughout the subtropical Atlantic Ocean and the Mediterranean Sea, which is known as a generalist predator and opportunistic feeder. The ongoing climate changes and seawater warming may favour fireworm poleward range expansions and density increases. Our results provide the first investigation into a population which has purportedly been spreading widely in the Salento Peninsula (Apulia, Italy). The specimens were analysed using allometric variables and molecular markers. The best morphometric parameters to estimate individual size were determined as key information for future studies on fireworm population dynamics. To phylogeographically characterize the Apulian population, sequences of the mitochondrial COI and 16S rDNA regions were obtained from a pool of individuals and treated together with those of Atlantic specimens retrieved from GenBank. The estimates of genetic variability for Apulian population were consistent with those recently reported in the literature. Inferences on demographic history analysis confirmed a recent expansion event in Apulia, as has been recounted by fishermen and scuba divers during recent years. Overall, these results constitute a crucial step in the characterization of present-day H. carunculata populations, and provide greater insight into fireworm population ecology.

Abstract: THE USE OF HISTOLOGY, MOLECULAR TECHNIQUES, AND EX SITU FEEDING EXPERIMENTS TO INVESTIGATE THE FEEDING BEHAVIOR OF THE CORAL REEF PREDATOR HERMODICE CARUNCULATA, THE BEARDED FIREWORM Staci Lewis, MS George Mason University, 2009 Thesis Director: Dr. Robert Jonas Three studies on the invertebrate corallivore Hermodice carunculata, commonly known as the bearded fireworm, were conducted to provide baseline information on the general anatomical features, nutritional requirements, feeding behavior, and growth rates of this poorly documented reef inhabitant. Through histological techniques, the species’ feeding mechanisms, digestive system, and sensory structures were studied to understand its ability to adapt to a changing reef habitat. Several previously unreported features were observed including a simple layer of cells on the outer cuticle resembling, and the size of, bacteria, a specialized tissue in the foregut, and pigment granules penetrating the ventral cuticle at the nerve cord connection. This study also documented the appearance of gut content in the digestive tract and the presence of secretory cells on the proboscis. These observations provide insight into the feeding behavior of H. carunculata. Ex situ feeding experiments were conducted in Barbados to monitor organisms’ weight change in different coral reef feeding regimes as an indication of nutritional value of coral species. During the experiments, H. carunculata specimens experienced a Millepora complanata feeding regime and a short time period in a Montastraea annularis feeding regime. In both experiments, the average weight change was not statistically significant, which indicates the H. carunculata specimens did not gain weight in the presence of M. complanata. These results suggest H. carunculata may supplement their diet with other food sources to meet nutritional requirements. Finally, during an outbreak of an unknown white syndrome on coral colonies in the Flower Garden Banks National Marine Sanctuary, field samples, including H. carunculata specimens associated with the coral tissue loss margins, were collected to test the use of the Polymerase Chain Reaction (PCR) and DNA fingerprinting to identify H. carunculata associated with tissue loss lesions. Specific H. carunculata primers were designed to amplify H. carunculata DNA in the samples. The H. carunculata tissue samples (positive controls) were the only samples amplified during the PCR tests. These results suggest H. carunculata organisms do not leave detectable amounts of DNA at foraging sites. However, future molecular tests should be conducted using other target sequences for amplification and take into considerations the sensitivity of conditions including the number of PCR cycles.

Abstract: The bearded fireworm, Hermodice carunculata, is a common species in the marine annelid taxon Amphinomidae. It has a widespread distribution throughout the Atlantic, Gulf of Mexico, the Caribbean, Mediterranean and Red Seas. We review its environmental tolerances, defence mechanisms and feeding habits to evaluate its potential to survive in changing ocean conditions, to increasingly emerge as a nuisance species and to invade new geographic areas. Hermodice carunculata tolerates a wide range of environmental conditions, including temperature, salinity, oxygen saturation and various types of pollution. It has few natural predators because it is protected by its sharp chaetae and probably by toxins. Hermodice carunculata is best known for consuming live cnidarians, and has been implicated in transmitting coral pathogens, but it also feeds non-selectively on detritus. In the short term, we predict that H. carunculata will be able to withstand many future ecological challenges and possibly contribute to coral reef decline. In the long term, ocean acidification may negatively impact its defence mechanisms and survival. Its invasive potential may be significant. We highlight the gaps in our knowledge about the reproduction and development of this species, the nature and origin of its toxins and role of microbes in their feeding behaviour and defensive strategies.

Abstract: The bearded fireworm (Hermodice carunculata) is an amphinomid polychaete with a circumtropical Atlantic-Mediterranean distribution. In the Mediterranean Sea, very little information is available on...