Distribution of mangrove sesarmid crabs (Crustacea: Brachyura) in northeastern Australia PDF
Preview Distribution of mangrove sesarmid crabs (Crustacea: Brachyura) in northeastern Australia
MEMOIRS OF THE QUEENSLAND MUSEUM 93 4 4 a? DISTRIBLTION OF MANGROVE SESARMID SSS , Bee whritte Fi/ c | CRABS (CRUSTACEA: BRACHYURA) IN h- NORTHEASTERN AUSTRALIA Taveee ooo res Sesarmid crabs have been shown to be an important com- Vi tone eae te 4 \ pres ponent of mangrove ecosystems in tropical Australia ume Wem (Robertson. 1986; Smith, 1987). Despite their dominance in fiero * ": rT iat mangrove forests (Jones, 1984) there is litile information on A 4 whew e the distribution of sesarmid crabs bewh between and within j vee | =. \ estuaries of tropical Australia, P, Davie (Queensland (mony te eos - - 1 Museum) is Working on the taxonomy of the group and ts describing the new species discussed in (his paper. +t, ee aons / Materials and Sampling Sites Pitfall traps were used lo determine crab abundances. I 4e i Within estuary sampling was undertaken a! Hinchinbrook << e Island, Murray River and Cape Ferguson (Fig. |). Between estuary sampling was undertaken in the Endeavour, Morgan. rovn Claudie, Escape and Wenlock Rivers (Fig, 1). Opportunistic cies from colonizing eastern Australia, but that tropical east hand collections of crabs were also available tram the Fly coast fauna could be swept via larvae or adults onta northern Raver. coasis, The present study shows that Torres Strait is nol a barrier fora t least one typical northern species, §, sp. nov, 2, Results which is able lo penetrate some distance south along eastern Five species accounted for over 90% of crabs captured al Cape York Peninsula and onto the coast of Papua New Hinchinbrook Island, Murray River und Cape Ferguson, At Guinea. The existing distribution patterns of the dominant the moutlrof these estuaries, in high salinity regions, Sesarma sesarmid crab fauna associated with mangroves in NE Aus- semperilongicristutiam dominated in the low intertidal adja- iraliadnd SW PNG can only partially be explained by simple cent to the mudflat. This species was replaced by 5. messa physical coastal oceanographic features. As Davie (1985) which dominated catches in the intertidal region up to the suppesied, further studies are needed to elucidate larval/adult terrestrial mangrove interface where S. fourmanvir] domi- disinbution patterns for these species. If the dominant sesar- nated. In the medium and lower salinity regions of estuaries mid species are <keystone species9, then knowledge of the the mangrove region is reduced to normally less than 3Um., colonization factors which determine distribution is impor- As such, the dominant crab distributions showed no dilter- (ant. As the tropical littoral zones come under increasing ence with intertidal position.§ .m essa dominated the medium pressure through urbanization, development and subsequent sulinily regions of the mangrave forests, giving way to S. pollution, logether with the predicted effects of the 'green- brevipes in the low salinity regions. §. brevicristanim was house phenomena9, a correct Understanding will be impera- sub-dominant in the medium and low sulinity regions. The live when the biological components of these littoral Endeavour, Morgan and Claudie Rivers had within estuary ecosysiems are forced to adapt and alter distribution patierns, crab distributions similiar to those described above. The Wenlock River had 4 completely different sesarmid fauna to Literuture Cited the northeast coast rivers. S. darwinensis dominated high Davie, PLP. 1985. The biogeography of littoral crabs salinity Jow intertidal regions and was co-dominaot with (Crustacea: Decapoda: Brachyura) associated with tidal Sesarma sp. nov. 2 in the mid- to high intertidal regions, In wetlands in trepical andsub-tropical Australia. 259-276, ihe low salinily regions Sesarmsap , poy- 1 dominated. The In J. Chappell, J.D.S. Davie, and C. Woodrotfe(eds.) Escape River could only be sampled in the medium and high <Coasts and lidal wetlands of the Australian monsoon salinity regions. Within estuary crab distributions reflected region9. Proceedings of a conference held on 4-11 both east coast aid Wenlock River distribuons. 8. semperi November 1984, Darwin, N_A.R.U. Monograph Series. longicristatum and S. messa distributions were similiar to the Jones. D.A. 1984. Crabs. of the mangal ecosystem, 89-109, other east coast rivers and §. sp, nov, 2 replaced §. four- in F.D, Por and 1. Dor (eds.) <Hydrobiology of the manoiri as well as being co-dominant with S. esse in the mangal (W. Junk: The Haguc). medium salinity rogions. In the Claudie River S. sp. nov. 2 Robertson, A.!. 1986, Leal-burying crabs: their influence on was noliced adjacent to a large population of §, fourmaneirt, energy Mow and export [rom mixed mangrove forests (Rhizophora spp.) in northeastern Australia, Journal of S.messa and S. sp. nov. 2 were bath collected from the lower reaches of the Fly River, Fig. 1 shows the distributions als. Experimental Marine Biology and Ecology 102: 237- 248, messa. §, fourmanoiri and S sp. nov. 2 found in these Smith, Tu, 1]f, 1987, Seed predation ia relation to tree dom- surveys. inance and distribution in mangrove forests, Ecology 68(2): 266-273. Discussion Davie (1985), in tryingt oe xplain the apparent segregation af northern coast endemic species (o westwards of he Torres §.D. Frasher, RL. Giddins and TJ. Smith 11, Strait region, suggested that current flow westwards through Australian Institute ef Marine Science, PMB No. 3, Torres Strait could effectively prevent northern derived spe- MC Townsville 4810, Australia,
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