Study Of Crabs To Intertidal Stimuli :: essays research papers

INTRODUCTION- Since its itroduction to the New Jersey shore in 1988, the western peaceable shorecrab Hemigrapsus sanguineus has spread to inhabit grating intertidal locations on theAtlantic coast from Massachusetts to North Carolina (McDermott 1998). umpteen reasonshave been proposed to explain the rapid spread of this non-indiginous species. Forexample, it has been shown that H. sanguineus has longer spawning periods along the mid-Atlantic coast than it does in its natural habitat in the western Pacific Ocean, due toa more favorable climate (Epifanio et al 1998). For this reason, these manoeuver are able tospawn more times per season than natal crabs, providing one possible hypothesisfor their population explotion.For this species to expand its jog along the Atlantic coast, it will need to havewide tolerances to temperature and salinity. In 1998 Epifanio order that The purpose of this study is to show the tolerance and behavioral responses of H.sanguineus to varying pissin g and air temperatures, and urine salinity concentrations. It isbelieved that these crabs will be really tolerant to the various extreme conditions that theywill be put through. It is the cogency of these crabs to survive in these unfavorablesituations that is key to their success. This experiment was in like manner designed to prove thehypothesis that the tolerance of H. sanguineus to various environmental factors increaseswith size.METHODS AND MATERIALS-In February 2000, a field trip was taken to Crane Neck take down to collect livespecimens for the experiment. The field trip was mannersed at low tide. The watertemperature was approximately 3 stagecoachs Celcius, with the air temperature slightly abovefreezing (0-1 degree Celcius). Live crabs were obtained by overturning rocks in theintertidal zone. Hemigrapsus sanguineus was found at all levels of the intertidal zone,although their numbers increased as one locomote toward the waterline. The crabs werecollected with no dis tinction toward size. The sizes of the specimens collected werefound to range from 0.5 to 4.2 cm. The crabs were collected in a plastic five gallonbucket. Water was added to the bucket to keep the crabs from dehydrating. The crabswere taken prat to the lab, where they were kept in the plastic five gallon buckets for a fewer weeks until the experiment began. Air hoses were added to the buckets in order tooxygenate the water. The water was changed, as necessary. The first experiment conducted was the experiment regarding water temperatureand salinity tolerances. The objective was to conduct an experiment that would providemeasurable data on the tolerance of H.