|
Abstract
ECOLOGY OF THE BLUE CRAB (CALLINECTES SAPIDUS)
LIFE HISTORY
Anson H. Hines1, Margaret Kramer1, Rob Aguilar1,
Eric Johnson1, Alicia Young1, Michael Goodison1, Greg Ruiz1, Joseph
Dineen2, Sherry Reed2, Thomas Wolcott3, Paul Jivoff4, David Smith5,
and Romuald Lipcius6
1Smithsonian Environmental Research Center
2Smithsonian Marine Station at Fort Pierce
3North Carolina State University
4Rider University
5Smith College
6Virginia Institute of Marine Science
Bio
For 28 years we have applied diverse techniques to determine the
ecology of blue crab life history stages in estuaries along eastern
North America, especially Chesapeake Bay and the Indian River Lagoon.
Experiments show females produce 1-4 broods annually in Chesapeake
Bay and 3-8 broods in Florida. Pump sampling shows hatched surface-swimming
zoeae are transport seaward onto the continental shelf. Megalops
undergo selective tidal stream transport on nocturnal spring flood
tides for return into estuaries, where passive larval collectors
indicate they settle on sharp semi-lunar peaks into seagrass beds.
After growing to 6-7th crab instar (20mm), juveniles are caught
by surface beam trawls on nocturnal flood tides while dispersing
to low-salinity nursery habitats. Hatchery-reared batches of small
20mm juveniles injected with micro-wire and elastomer remain to
grow within shallow coves with fringing marshes. Small biotelemetry
tags reveal juveniles forage in nearshore shallows, where tethering
indicates mortality is decreased. Telemetry also shows that juveniles
move to coarse woody debris of fallen trees to obtain refuge during
molting. Strategic trapping and customized telemetry of movement,
feeding, agonism, molting, and mating show that males undergoing
their pubertal molt move into salt creek habitats away from cannibalistic
intermolt adults. Females molt to maturity move near the mouths
of subestuaries to pair with intermolt adult males, and mating experiments
indicate male size, mating history and sex ratio affect sperm stores.
Foraging adult crabs forage in deeper (>1m) water of subestuaries
where they meander slowly (10m/hr) and aggregate on clam patches
until agonism stimulates rapid (400-1000m/hr) departure to a new
prey patch. In fall fishery returns of externally tagged crabs show
males move into adjacent deeper waters; whereas mature females migrate
down estuary along channels to spawning areas. Movement ceases below
10oC in winter. Our studies provide unusually comprehensive insight
into ecology of this important species.
|
