Fisheries Behavioral Ecology - Abstracts
van Montfrans, J., C.H. Ryer, and R.J. Orth. 2003. Substrate selection by blue crab Callinectes sapidus megalopae and first juvenile instars. Marine Ecology Progress Series 260:209-217.
Abstract
Various marine and estuarine species utilize chemical cues during settlement. We investigated
responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates
in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1
crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera
marina and artificial seagrass in replicate 160 l tanks. Either 10 megalopae or J1 crabs isolated in
each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal
distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30 % of J1
crabs (with only 17% recovered from Z. marina) were found in live C. virginica. A field experiment
quantified responses of ingressing megalopae to Z. marina, marsh mud, and C. virginica. Overnight
settlement was significantly higher in Z. marina (x = 3.3 ind.; 60% of total) when compared to mud
(x = 0.9; 16 %) or C. virginica (x = 1.3; 24 %). Likewise, J1 crabs were significantly more numerous
in Z. marina (x = 3.7 ind.; 55% of total) than in C. virginica (x = 1.8; 27 %) and mud (x = 1.2; 18 %).
J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results
were equivocal and probably due to artifacts associated with density-dependent agonism. The initial
non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitat-selection
behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal
survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species
with comparable habitat requirements and life-history characteristics.
Last updated
26 April, 2007
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