. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION OF OVIGEROUS BLUE CRABS 171 ebb-tide transport). The results also suggest that after spawning, female crabs reverse direction and move up the estuary in a saltatorial fashion (, flood-tide trans- port). A change in the direction of migration requires that the mechanisms responsible for synchronizing the vertical migratory behavior of female crabs with the appropriate tidal currents must shift 180° (, «6 h) following larval release. Alternatively, ovigerous and post-spawning crabs may rely on different mecha
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION OF OVIGEROUS BLUE CRABS 171 ebb-tide transport). The results also suggest that after spawning, female crabs reverse direction and move up the estuary in a saltatorial fashion (, flood-tide trans- port). A change in the direction of migration requires that the mechanisms responsible for synchronizing the vertical migratory behavior of female crabs with the appropriate tidal currents must shift 180° (, «6 h) following larval release. Alternatively, ovigerous and post-spawning crabs may rely on different mechanisms or cues to time their forays into the water column. This migratory pattern is apparently not unique to the Newport River Estuary. In an extensive mark-recapture study conducted in the St. Johns River. Florida, Tagatz (13) found that females with developing eggs migrate from the river to the ocean just prior to larval release. Ovigerous crabs collected within the river had primarily yellow-orange egg masses, whereas most of those col- lected near the river's mouth and in coastal waters had dark brown or black sponges. Blue crabs that had recently possessed sponges were also observed reentering the lower 40 km of the river and developing a second sponge. Tagatz (13) also reported that several sponge crabs tagged in coastal waters lacked egg masses when they were re- captured in the river within a couple of weeks of their release. Based upon our observations of the migratory behavior of ovigerous blue crabs in the Newport River Estuary and the results of previous mark-recapture studies [see (5) for review], we have developed u conceptual model for the seaward migration of female blue crabs for spawning. The model is divided into two phases—a long-distance down-estuary phase in which newly inseminated non- ovigerous crabs travel seaward toward the lower reaches of the estuary (Phase I; Fig. 2), and a shorter distance spawning phase in which ovigerous crabs migrate from eu
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
