Morphometric and molecular characterization of an expanding Ionian population of the firewormHermodice carunculata(Annelida)

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.

First description of early developmental stages of the native invasive fireworm Hermodice carunculata (Annelida, Amphinomidae): a cue to the warming of the Mediterranean Sea

“…The bearded fireworm is known as a voracious opportunistic consumer of a wide range of live prey items, with the potential to change its diet according to ongoing environmental envelopes and food availability, even adopting a scavenger behavior (Simonini et al, 2017(Simonini et al, , 2018. As in other amphinomid species (Cosentino & Giacobbe 2011;Arias et al, 2013), a number of biological traits -adaptive dietary plasticity, high physiological tolerance, and presumed long larval dispersal -predisposes H. carunculata to become a highly invasive species able to take advantage of warming ocean conditions worldwide (Schultze et al, 2017;Righi et al, 2019).…”

Ecology, distribution and expansion of a Mediterranean native invader, the fireworm Hermodice carunculata (Annelida)

“…Indeed, posts on social networks have provided images of some of the largest specimens of H. carunculata observed so far. On the basis of the relationship between the number of chaetigers and body length (Righi et al, 2019), fireworms photographed at Sapri (Gulf of Policastro, Tyrrhenian Sea), Cala di Puolo (Gulf of Naples) and Salina (Aeolian Islands) had body lengths of about 77 cm, 51 cm and 50 cm. Previous studies reported maximum length of 30-60 cm (estimated by divers, Chafarinas Islands, Western Mediterranean Sea; Maldonado et al, 2013), 30 cm (Righi et al, 2019) and 25 cm in length (Yáñez-Rivera & Salazar-Vallejo, 2011).…”

“…Cases of fireworms feeding on dead fish or bait were also numbered. Finally, if the images had high resolution and included the whole animal, the number of chaetigers was counted to estimate fireworm body length using the morphometric relationship y = 0.0073x 1.7412 (Righi et al, 2019). Then, the fireworms were classified as small (< 10 cm), medium (10-20 cm) or large (> 20 cm).…”

“…The biggest specimens were photographed in the Tyrrhenian Sea at Sapri (Gulf of Policastro), Cala di Puolo (Gulf of Naples) and Salina (Aeolian Islands). They showed 205, 162 and 160 chaetigers respectively, corresponding to estimated body lengths of about 77 cm, 51 cm and 50 cm, respectively, according to the relationship calculated between the number of chaetigers and body length (Righi et al, 2019; see Table S2 for the links to the web pages).…”

“…On the other hand, there are relatively few studies on the biology and distribution of H. carunculata colonizing the Italian coasts and the study of Mediterranean populations and their potential impacts on benthic communities has just started. A first expanding population able to prey on a sea urchin keystone species has been detected in Apulia (Simonini et al, 2017;Righi et al, 2019). In the lab, Mediterranean H. carunculata specimens turned out to be generalist predators of several benthic invertebrates, displaying powerful defensive capacities to ensure predator escape and opportunistic feeding habits (for an extensive list of prey organisms see Simonini et al, 2018).…”