Spatial structure in a stone crab population (Brachyura: Xanthidae) and the interplay with resource mosaics

1 Pages·1991·1.1 MB·

by  W J Lindberg

MEMOIRS OF THE QUEENSLAND MUSEUM
SPATIAL STRUCTURE IN A STONE CRAB Changes with access to prey, and the resultant mosaic thon
POPULATION (BRACHYURA:XANTHIDAE) influences residency patierns by size and sex.
AND THE INTERPLAY WITH RESOURCE Low site fidelity by males compared to females and mul-
MOSAICS tiple male occupancy of modules (Wilber, 1989a; and herein)
For large, motile, den-dwelling decapuds (e.g, clawed and precludes 4 resoutce-centred male mating strategy. Pro-
spiny lobsters) habitat should be considered a mosaic of tracted mate guarding (Wilber, 1989b) also impugns an
resource patches. Patchiness affects access lu resources encounter-raic-competition male strategy. The greater per
which, in turn, affects mating patterns wilhin populations cupila mating success of males on wide plots, and resightings
(Emlen and Oring, 1977), For some small brachyurans, of few large males amidst numerous females is consistent
patchiness of refuge or premium burrowing sites factors into with ether a female-centred, patrol-and-de fend stralegy ora
male mating success (Christy, 1983; Diesel, 1986; Abele ef search-and-defend strategy influenced by patterns of food
al., 1986), We asked if population structure of commercially and refuge.
important stone crabs would vary with refuge patchiness
sufficiently to exclude alternative mating Strategies as de- Acknowledgements
fined by Christy (1987). This. work was funded by the Florida Sea Grant College
Program, U.S. Department of Commerce, grants NAROAA-
Methods D-00038 and NAS6AA-D-SGO68.
Refuge spatial patterns were manipulated as a splil-plot
experimental design for a population of hybrid stone crabs Literature Cited
(Menippe mercenaria x M. adina) in the northeastern Gulf Abele. L.G., Campanella, P_J. and Salmon, M. 1986, Natural
of Mexico. Six interspersed treatment plots each contained history and soctal organization of the semiterrestrial
36 prefabricated Teel modules in either a widely spaced grapsid crab Pachygrapsus transversus (Gibbes), Jour-
(60m), uniform pattern, a closely spaced (2m) uniform pal- nal of Experimental Marine Bivlogy and Beolowy 104:
tern, or an intermediate, mixed pattern, ic. G widely spaced 153-170.
clusters, each with 6 closely spaced modules. In September Bert. TM, and Harrison, R.G, 1988, Hybridization in West-
and October, 1987, 12 randomly selected modules were ern Atlantic stone crabs (Genus Menippe): evolutionary
non-desiructively sampled on each plot. In late August and history and ecological context influence species interac-
early October, 1987, one black of treatment plots was ¢xhau- tions. Evolution 42: 528-544,
slively bul non-destructively sampled (n = 36 modules/plot). Christy, J,H, 1983, Female choice in the resource-defense
That sume block was exhaustively sumpled monthly trom mating system of (he sand fiddler crab, Vea pugilator.
August 1988 through July 1989. Data foreach crab included Behavioral Ecology and Sociobiology 12; 169-180,
specific den Jocation, tag identification, sex, carapace width, 1987. Competitive mating, mate choice and mating associa-
and phenotypic index according to Bert and Harrison (1988) tions of brachyuran crabs, Bulletin of Marine Science
44: 177-191.
Summary of Results Diesel, R. 1986, Optimal mate searching strategy In the
Phenotypically, this hybrid population most closely re- symbiotic spider crab /nachus phalangium (Decapoda),
sembled M, shercentaria, In 1987, widely spaced modules Ethology 72; 311-238.
harboured more crabs than did closely spaced modules or Emlen,S,T. and Oring, L,W, 1977. Ecology, sexual selection
those in an intermediate, mixed pallern, Widely spaced an and the evolution of mating sysiems. Sejence 197; 215-
mixed modules also tended to harbour larger males und 333,
females, although differences were not significant for every Lindberg, W.J., Prazer, T.K. und Stanton, G.R. In Press.
sampling period, Sex ratios did not differ among lreatments, Population effects ot refuge dispersion for adult stone
yel widely spaced modyles harboured more mated pairs than crabs (Xanthidae, Mvnippe), Marine Eulogy Progress
expected from the distribution of males among plois 8Series.
Crabs left the study site during late summer und fal] 1988 Wilber, D, H, 19899, Reproductive biology and distribution
as Octopus vulgaris invaded plots, Treatment elects re- of stone crabs (Xanthidac, Menippe') in the hybrid zone
emerged tollowing spring 1989 recolonisation by adult crabs. on the northeastern Gulf of Mexico. Marine Ecalogy
Crabs tagged in 1989 were not long-term den residents, bur Progress Series 52; 235-244,
resightings were preater than expected by chance on the wide 1989b. The influence of sexual selection and predation on
plot. Females were tesighted more often than males. Only 5 the mating and postcopulatory guarding behavior of
of 100 tagged males were resighted, three resighted justonce, stone crabs (Xanthidac, Menippe), Behavioral Ecology
and two large males (122 mm and 10 mm CW) found and Sociobiology 24; 445-451.
repeatedly in different wide-plot modules with different
females. Wid. Lindberg and T.K. Frazer, Department of
Fisheries and Aquaculture, University of Florida,
Discussivn
Gainesville, Florida USA.
Differences in. crab abundance may be explained by difver-
ential prey depletion on soft-boltom as a function of refuge
spacing and distance from refuge (Lindberg ef a/,, in press, G.R. Stanton, Florida Stee University Marine
Frazer and Lindberg, unpubl.). Refuge value apparently Lubaralery, Tallahassee, Florida USA,