Biology and interspecific interactions of the alien crabPercnon gibbesiin the Maltese Islands

Abstract

Spatial and bathymetric distribution, population density, habitat preferences, fecundity, breeding season and interspecific interactions of the alien grapsoid crab Percnon gibbesi (H. Milne-Edwards, 1853) from the Maltese Islands (Malta and Gozo) are compared among localities in the Mediterranean where established populations have been reported since 1999. In the Maltese Islands, habitat preferences and bathymetric distribution were similar to those in other Mediterranean localities. Spatial distribution was found to be limited by the availability of the boulder habitat in which this crab nearly always occurs. Fecundity was higher in the Maltese Islands than in Linosa and Lampedusa, the breeding season lasting from the end of May until September. On Maltese shores the habitat of the alien overlapped with that of the native grapsid Pachygrapsus marmoratus (Fabricius, 1787) (Crustacea: Brachyura: Grapsoidea) and, to a lesser extent, that of the native xanthid Eriphia verrucosa (Forskål, 1775). Laboratory studies to assess the possible interactions of the alien species with P. marmoratus suggest that the latter shows a competitive advantage over P. gibbesi, since 80.8% of encounters between the two species were initiated by P. marmoratus, and in 80% of the encounters it prevailed. This suggests that P. marmoratus is unlikely to be excluded from its natural habitat by the alien species, and that significant spatial resource partitioning on the part of P. marmoratus is unlikely to occur.

Physiological adaptation to Mediterranean habitats of the native crab <em>Pachygrapsus marmoratus</em> and the invasive <em>Percnon gibbesi</em> (Crustacea: Decapoda)

“…In fact, P. marmoratus mainly inhabits supralittoral crevices (Augusto andFlores 2001, Deudero et al 2005), whereas P. gibbesi shows no tendency towards a semi-terrestrial lifestyle, with limited bathymetric distribution restricted to the infralittoral zone from 0 to 4 m depth. Laboratory experiments indicated that when competing for space, P. marmoratus dominates the interactions with P. gibbesi (Sciberras and Schembri 2008). The present results provide new biochemical evidence suggesting that P. gibbesi and P. marmoratus do not compete for space and there is no spatial overlap, so P. marmoratus is not excluded from its natural habitat by the alien species.…”

“…These characteristics suggest that the ecological niche of P. gibbesi does not interfere with that of other benthic organisms such as P. marmoratus (Deudero et al 2005). Moreover, previous studies have found no competitive interactions between P. gibbesi and P. marmoratus that could be a consequence of their physiological status and this finding is also supported through biochemical analysis (Deudero et al 2005, Sciberras andSchembri 2008). We hypothesize that aerial exposure could result in increased antioxidant enzymes and vitamin E content as a response to UV radiation and atmospheric oxygen.…”

Invading the Adriatic: spatial patterns of marine alien species across the Ionian–Adriatic boundary

“…It is a primarily algivorous crab of the shallow infralittoral rocky shores (usually < 4 m depth) and may reach densities of 10 ind. m 2 (Sciberras & Schembri 2008, Raineri & Savini 2010. Its widespread and expanding distribution along the Mediterranean coasts and the high rates of increase in abundance denote a highly invasive species ).…”

Substrate preference and settlement behaviour of the megalopa of the invasive crab Percnon gibbesi (Decapoda, Percnidae) in the Mediterranean Sea

“…While some aspects of the biology and ecology of adult P. gibbesi have been investigated [25][26][27][28][29][30], little is known on its larval stages. A major reason could be the low efficiency of traditional sampling gear (e.g., plankton nets) in collecting a sufficient number of living and healthy larvae.…”