Host use pattern of the pea crab Afropinnotheres monodi: potential effects on its reproductive success and geographical expansion

Abstract

The successful settlement of the African pea crab Afropinnotheres monodi in the Bay of Cadiz was analysed to get new insights into the evolution of pea crab parasite life history traits. The pea crab lives symbiotically and with high prevalence in the bivalves Cerastoderma glaucum and Mytilus galloprovincialis, and with low prevalence in Scrobicularia plana. A remarkable monopolisation of host (one crab/bivalve) occurred irrespective of host species and crab demographic categories (males, hard females, soft females), probably as an optimisation of resources in smallsize hosts. However, there was a clear asymmetry in host use by the different crab 2 categories. A 1:1 sex ratio was found in crabs harboured by C. glaucum and S. plana, with most of the female crabs being small and hard specimens, whereas crabs inhabiting M. galloprovincialis were primarily large reproductive females. Ovigerous females were found throughout the year in M. galloprovincialis and there was a strong correlation between female size and fecundity, suggesting that the females harboured by this host were the major contributors to the reproductive effort of the studied population. Conversely, most of the new crabs recruiting to the population were harboured by the remaining two host species. We hypothesise that such a generalist but asymmetrical usage of bivalve hosts by pea crabs may have clear benefits for species in geographical expansion as A. monodi, facilitating its dispersal to new locations and its successful settlement in sheltered systems, as the Bay of Cadiz.

Annotated checklist of brachyuran crabs (Crustacea: Decapoda) of the Iberian Peninsula (SW Europe)

“…This was the third report for this species worldwide. Although it is probably a case of natural range expansion, an introduction by fouling should not be discarded, given that the mussel Mytilus galloprovincialis is one of its main hosts (Drake et al 2014). …”

Freshwater scarcity effects on the aquatic macrofauna of a European Mediterranean-climate estuary

“…This is irrespective of the occurrence of African species due to its close location to the northern African coast (Rodríguez et al, 1997;Castañeda and Drake, 2008;Drake et al, 2014). Furthermore, during the last few decades, annual freshwater discharge of the Guadalquivir River has displayed the largest decrease (84%) of all large European rivers (Milliman et al, 2008).…”

Larval development of the pea crabAfropinnotheres monodiManning, 1993 (Decapoda, Pinnotheridae) using plankton-collected and laboratory-reared specimens: effects of temperature

“…Until then, this small pinnotherid crab had a recorded distribution restricted to four localities, two in Morocco and two in Mauritania, but with no data on their hosts (Manning 1993). The populations inhabiting the Gulf of Cádiz have now been studied, and data are available on their hosts as well as on the period of reproduction (Drake et al 2014). Afropinnotheres monodi has a large number of bivalve hosts, and has been collected with varying degrees of prevalence from Scrobicularia plana (da Costa, 1778), Cerastoderma glaucum (Bruguière, 1789), Chamelea gallina (Linnaeus, 1758), Donax trunculus Linnaeus, 1758, Mactra stultorum (Linnaeus, 1758), Spisula solida (Linnaeus, 1758), Ruditapes decussatus (Linnaeus, 1758) and the mussel Mytilus galloprovincialis Lamarck, 1819, in which the ovigerous females reach a larger size and therefore have a higher number of eggs (Drake et al 2014).…”

“…The populations inhabiting the Gulf of Cádiz have now been studied, and data are available on their hosts as well as on the period of reproduction (Drake et al 2014). Afropinnotheres monodi has a large number of bivalve hosts, and has been collected with varying degrees of prevalence from Scrobicularia plana (da Costa, 1778), Cerastoderma glaucum (Bruguière, 1789), Chamelea gallina (Linnaeus, 1758), Donax trunculus Linnaeus, 1758, Mactra stultorum (Linnaeus, 1758), Spisula solida (Linnaeus, 1758), Ruditapes decussatus (Linnaeus, 1758) and the mussel Mytilus galloprovincialis Lamarck, 1819, in which the ovigerous females reach a larger size and therefore have a higher number of eggs (Drake et al 2014). In a similar way to other species originating from Africa, A. monodi reproduce throughout the year, although the lowest number of ovigerous females was observed in the autumn and zoea stage I in the winter (Drake et al 1998).…”