On the distribution, diet and possible impact of the invasive European shore crabCarcinus maenas(L.) along the South African coast

Abstract

The crab Carcinus maenas (L.) has an endemic distribution along the European Atlantic coastline but has been accidentally introduced into intertidal habitats in several parts of the world. Its discovery al the Cape Peninsula in South Africa is recorded here. The crab is well established in Table Bay harbour and the population is at least seven years old. From here it has spread 117 km north and 10 km south. Populations on the open coast are more recently established. The crab feeds on a wide range of intertidal animals, particularly the isopod Paridotea ungulaw, limpets and polychaetes, but it is too early to make quantitative assessments of its impact on local intertidal communities.Initial predation experiments suggest that the barnacle Notomegabalanus algieola and the whelks o.l)'stele I'l/riegata and O. tigrina have no refuge in size or zonation from the crab. O. sinensis, of similar size to O. tigrina, is less vulnerable by virtue of its stronger shell. Its critical size (above which it is too large to be attacked) is correlated with crab size. Larger species, such as the mussels Chorom)'lilus meridionalis and Aulacomya ateI' and the periwinkle Turbo sarmatieus, clearly achieve a refuge in size, but predation on their recruits may influence their abundance and size structure. C. maenas rejected only the urchin Pareehinus angulosus as a source of food. While it is conceivable that shifts in community structure, selection for thicker shells in molluscs and localized extinction of certain species may occur at high crab densities, it is predicted that C. maenas will only have a significant impact in areas protected from wave action.Die krap Carcinus maenas (L.) kom endemics langs die Atlantiese kuslyn van Europa voor, maar is per ongeluk in lussengetyse habitatte van etlike werelddele ingebring. Sy ontdekking langs dic Kaapse Skiereiland in Suid-Afrika word hiermee geboekstaaf. Die krap is goed gevestig in Tafelbaai, en die bevolking is ten minste sewe jaar oud. Hiervandaan het dit 117 km noord en 10 km suid versprei. Bevolkings aan die onbeskutte kus is meer onlangs gevestig. Die krap teer op 'n wye verskeidenheid tussengelyse diere, veral die isopode ParidOiea ungulata, klipmossels en borselwurms, maar dit is te vroeg om nou al kwantitatiewe ramings van sy invloed op plaaslike tussengetyse gemeenskappe te maak. Voorlopige voedingstoetse dui daarop dat die scepok NOlomegabalanlls algicola en die wulke Ox)'slele variegara en O. ligrina geen ontvlugting in Of grootte of sonering van die krap vind nie. O. sinensis, van soortgelyke grootle as O. ligrina, is minder kwesbaar van wee sy sterker skulp. Sy kritieke grootte (waarbo hy te groot is om aangevalte word) hou verband met krapgrootte. Groter spesies, soos die mossels Choromyti/llS meridionalis en Aulacom)'a aler en die alikreukel Turbo sarmalieus, verwerf wei deeglik beskerming wanneer hul groot word, maar roofbedrywighede op hul rekrute kan die talrykheid en groottesamestelling be'invloed. C. maenas het net die seekastaiing Parechinl/s angulosus as 'n voedse...

Molt and reproduction of the European green crab Carcinus maenas (Decapoda: Portunidae) in Patagonia, Argentina

“…The species has spread northwards and southwards, and has been recorded in eastern North America and South Australia, although permanent populations were unlikely to become established in some locations (Carlton and Cohen 2003). However, a global dispersion has been taking place for the last 25 years to areas as distant as Japan (Sakai 1986), western North America (Cohen et al 1995), South Africa (Le Roux et al 1990), and the Patagonian Atlantic coast. In regard to the latter, the species was found along the central coasts of San Jorge Gulf (45°55' S) in 2001 (Vinuesa 2005), and in Camarones Bay, north to San Jorge Gulf (approximately 44°54' S), in 2003 (Hidalgo et al 2005).…”

Population demographics of native and newly ­invasive populations of the green crab Carcinus maenas

“…Crabs were collected in traps and by hand in (a, upper panels) Menai Straits, Gwynedd, UK (n = 5096), and (b, lower panels) Barkley Sound, British Columbia, Canada (n = 1792) 1982). However, seawater temperatures in the Menai Strait (Harvey 1972) and Barkley Sound (Bamfield Marine Sciences Centre, Ocean News Records) are similar, and in South Africa, where water temperatures are warmer and the growing season is longer, the crabs are no larger than their native counterparts (Le Roux et al 1990). Prey items are also plentiful in both areas, and there is little evidence to suggest that growth in crabs from Europe is limited by food availability (Klein Breteler 1975, Berrill 1982.…”

“…To date, the maximum size attained by green crabs Carcinus maenas appears highly consistent, both in its native range and in locations where it has become established (Australia, east coast of North America, Patagonia, South Africa) and is classified as an invasive species (Ropes 1968, Le Roux et al 1990, Hidalgo et al 2005, Audet et al 2008 reported maximum sizes. In general, females were smaller than males, and, although they may reach >90 mm CW (J. Drewery, FRS Marine Labs, pers.…”

Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach

“…The green crab appeared to be the general top predator in the absence of Buccinum sp. It is well known as a voracious carnivore, feeding on mussels, clams, snails, worms, barnacles, seaweed, isopods and other crustaceans (Hardwick-Witman 1985;le Roux et al 1990;Smallegange and van de Meer 2003). Our results supported this view, as C. maenas (…”