Skip to main content Accessibility help

Spatial, Temporal and Tidal Variation in Crab Populations in the Forth Estuary, Scotland

  • S. Mathieson (a1) and A.J. Berry (a2)


Five species of crabs were recorded in the Forth Estuary, of which Liocarcinus depurator and Cancer pagurus were confined to the lowest reaches where salinities are 24–35%‰. Carcinus maenas, Liocarcinus holsatus and Hyas araneus also occurred in the middle estuary where salinities are 22–31%‰ in summer but often fall to ~12%‰ in winter. A very few L. depurator and Cancer pagurus were confined to the lower estuary and mostly occurred in low tide trawls in summer. Carcinus maenas alone was recorded much further up the estuary where salinities rarely exceed 0–5·7%‰. Carcinus maenas predominated numerically throughout with an overall mean density of 0·0075 m−2 in the middle and lower estuary. Carcinus maenas in the estuary channel measured 16·6–82·9 mm carapace width (CW) with a modal size–class of 50–60 mm. Males were outnumbered by females (0·68:1 overall), and more markedly in summer than winter. Yet males were significantly bigger on average than females. Egg-masses were borne by 7·5% of all trawled females, but by 31·1% in April–May. On adjacent shores, by contrast, the much higher numbers of C. maenas were nearly all <20 mm CW. Low water trawls yielded significantly more C. maenas, but significantly lower proportions of males, than high water trawls. Liocarcinus holsatus was most abundant within the mid-lower estuary basin, with numbers decreasing both upstream and at the estuary mouth. Males outnumbered females by 2·26:1 overall, and most markedly at the extremities of the range. Males were significantly bigger than females, although sizes of both generally increased towards the mouth of the estuary. Only three of the 101 females bore eggs. Low water trawls yielded slightly more L. holsatus than high water trawls. Numbers of H. araneus increased markedly from mid-estuary to the estuary mouth where counts averaged 0·0021 m−2. Males outnumbered females by 2·17:1, and more so among those >40 mm CW. No female bore eggs. Records of the presence of C. maenas, Liocarcinus sp. and Hyas sp. all increased in the estuary from 1985 to 1995 reflecting increases in intertidal faunal diversity and changes in industrial practices since the early 1980s.



Hide All
Aagaard, A., Warman, C.G. & Depledge, M.H., 1995. Tidal and seasonal changes in the temporal and spatial distribution of foraging Carcinus maenas in the weakly tidal littoral zone of Kerteminde Fjord, Denmark. Marine Ecology Progress Series, 122, 165172.
Allen, J.A., 1967. The fauna of the Clyde Sea area. Crustacea: Euphausiacea and Decapoda with an illustrated key to the British species. Millport, Scotland: Scottish Marine Biological Association, Millport.
Almaça, C., 1979. Note sur la biologie des populations de Carcinus maenas (L.) de la zone intertidale du Portugal occidental. Quaderni del Eaboratorio di Tecnologica della Pesca. Ancona, 3, 179185.
Atkinson, R.A. & Parsons, A.J., 1973. Seasonal patterns of migration and locomotor rhythmicity in populations of Carcinus. Netherlands Journal of Sea Research, 7, 8193.
Basford, D.J., Eleftheriou, A. & Raffaelli, D., 1989. The epifauna of the northern North Sea (56°–61°N). Journal of the Marine Biological Association of the United Kingdom, 69, 387–07.
Berrill, M., 1982. The life cycle of the green crab Carcinus maenas at the northern end of its range. Journal of Crustacean Biology, 2, 3139.
Choy, S.C., 1988. Reproductive biology of Liocarcinus puber and L. holsatus (Decapoda, Brachyura, Portunidae) from the Gower peninsula, South Wales. Marine Ecology. Pubblicazioni della Stazione Zoologica de Napoli I, 9, 227241.
Crothers, J. & Crothers, M., 1988. A key to the crabs and crab-like animals of British inshore waters. London: Field Studies Council. [Reprinted with minor alterations from Field Studies, (1983) 5, 753806.]
Crothers, J.H., 1967. The biology of the shore crab Carcinus maenas (L.). 1. The background – anatomy, growth and life history. Field Studies, 2, 407434.
Crothers, J.H., 1969. The distribution of crabs in Dale Roads (Milford Haven: Pembrokeshire) during summer. Field Studies, 3, 109124.
Dare, P.J. & Edwards, D.B., 1981. Underwater television observations on the intertidal movements of shore crabs, Carcinus maenas, across a mudflat. Journal of the Marine Biological Association of the United Kingdom, 61, 107116.
Dekker, R., 1989. The macrozoobenthos of the subtidal western Dutch Wadden Sea. 1. Biomass and species richness. Netherlands Journal of Sea Research, 23, 5768.
Dries, M., & Adelung, D., 1982. Die Schlei, ein Modell für die Verbreitung der Strandkrabbe Carcinus maenas. Helgoländer Meeresuntersuchungen, 35, 6577.
D'udekem-D'acoz, C., 1993. Activitiés reproductrices saisonnières des différentes classes de tailles d'une population de crabes verts Carcinus maenas (Linnaeus, 1758) dans le sud de la mer du Nord. Cahiers de Biologie Marine, 35, 113.
Elliott, M., & Kingston, P.F., 1987. The sublittoral fauna of the estuary and Firth of Forth, Scotland. Proceedings of the Royal Society of Edinburgh B, 93, 449465.
Elliott, M., O'reilly, M.G. & Taylor, C.J.L., 1990. The Forth estuary: a nursery and overwintering area for North Sea fishes. Hydrobiologia, 195, 89103.
Fernández, L., González-Gurriaran, E. & Freire, J., 1991. Population biology of Liocarcinus depurator (Brachyura: Portunidae) in mussel raft culture areas in the Ría de Arousa (Galicia, NW Spain). journal of the Marine Biological Association of the United Kingdom, 71, 375390.
Hostens, K. & Hamerlynck, O., 1994. The mobile epifauna of the soft bottoms in the subtidal Oosterschelde estuary: structure, function and impact of the storm-surge barrier. Hydrobiologia, 282–283, 479496.
Hunter, E. & Naylor, E. 1993. Intertidal migration by the shore crab Carcinus maenas. Marine Ecology Progress Series, 101, 131138.
Ingle, R.W., 1980. British crabs. London: British Museum (Natural History).
Jayamanne, S.C., 1995. Population dynamics, biology and ecology of the caridean shrimps; Crangon crangon Linnaeus, Crangon allmanni Kinahan and Pandalus montagui Leach in the estuary and Firth of Forth, Scotland. PhD thesis, University of Stirling, Scotland.
Jensen, K.T. & Jensen, J.N., 1985. The importance of some epibenthic predators on the density of juvenile benthic macrofauna in the Danish Wadden Sea. Journal of Experimental Marine Biology and Ecology, 89, 157174.
Klein, Breteler W.C.M., 1976. Settlement, growth and production of the shore crab, Carcinus maenas on tidal flats in the Dutch Wadden Sea. Netherlands Journal of Sea Research, 10, 354376.
McGaw, I.J. & Naylor, E., 1992. Distribution and rhythmic locomotor patterns of estuarine and open-shore populations of Carcinus maenas. journal of the Marine Biological Association of the United Kingdom, 72, 599609.
McLusky, D.S., 1987. Intertidal habitats and benthic macrofauna of the Forth estuary, Scotland. Proceedings of the Royal Society of Edinburgh B, 93, 389399.
Meeren, G.I. Van Der, 1992. Location of spawning shore crabs, Carcinus maenas (L., 1758) (Decapoda, Brachuyra). Crustaceana, 63, 9294.
Munch-Petersen, S., Sparre, P. & Hoffman, E., 1982. Abundance of the shore crab, Carcinus maenas (L.) estimated from mark-recapture experiments. Dana, 2, 97121.
Muus, B.J., 1967. The fauna of Danish estuaries and lagoons. Distribution and ecology of dominating species in the shallow reaches of Mesohaline zone. Meddelelser fra Danmarks Fiskeri-og Havundersøgelser, 5, 1316.
Naylor, E., 1962. Seasonal changes in a population of Carcinus maenas (L.) in the littoral zone. Journal of Animal Ecology, 31, 601609.
Perkins, E.J., 1974. The biology of estuaries and coastal waters. London: Academic Press.
Poulsen, E.M., 1949. On the distribution of the Brachyura (Crustacea, Decapoda) in Danish waters. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening i Kjøbenhavn, 111, 111130.
Roddie, B.D., 1988. Factors affecting the abundance and distribution of estuarine zooplankton, with special reference to the copepod Eurytemora affinis (Poppe). PhD thesis, University of Stirling, Scotland.
Venema, S.C., & Creutzberg, F., 1973. Seasonal migration of the swimming crab Macropipus holsatus in an estuarine area controlled by tidal streams. Netherlands Journal of Sea Research, 7, 94102.
Warman, C.G., Ried, D.G. & Naylor, E., 1993. Variation in the tidal migratory behaviour and rhythmic light-responsiveness in the shore crab, Carcinus maenas. Journal of the Marine Biological Association of the United Kingdom, 73, 355364.
Wolff, W.J. & Sandee, A.J.J., 1971. Distribution and ecology of the Decapoda Reptantia of the estuarine area of the rivers Rhine, Meuse, and Scheldt. Netherlands Journal of Sea Research, 5, 197226.

Spatial, Temporal and Tidal Variation in Crab Populations in the Forth Estuary, Scotland

  • S. Mathieson (a1) and A.J. Berry (a2)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed