Post by account_disabled on Oct 26, 2023 5:06:47 GMT -6
The present study surveyed the spatial distribution of the crab Ocypode quadrata according to the number and diameter of burrows found at Praia do Forno (22º58'S, 42°00'W), a sandy beach located in the municipality of Arraial do Cabo-RJ. Sampling was carried out on 05/01, 08/07 and 08/08/2015. Ten transects perpendicular to the waterline were randomly distributed, consisting of three rectangles measuring 2m x 5m, spaced 2 meters apart, with a distance of 50 meters from the next transect. The division into three rectangles aimed to sample the three areas of interest in the study, mid-coastal (ML), supra-coastal (SL) and vegetation (VG), determined from the influence of tidal variation on the beach environment.
All burrows with marks and evidence of the presence of the crab were counted in each transect and the diameters were measured (mm) with the aid of a europe mobile number list caliper. The SL area had a higher average number of burrows compared to ML and VG, with no significant difference found between ML and VG. In the distribution of burrows by average diameter, a significant difference was found between all environments, with the burrows found in VG being those with the largest diameter, followed by the burrows in SL, and later the ML with the smallest diameter, possibly due to the sensitive dehydration of individuals of smaller size of O.quadrata.
The work found that larger individuals look for vegetation to build their burrows, as they have better mobility and independence from the nearest aquatic environment than smaller individuals, having the ability to excavate deep burrows. Furthermore, the subdivision into three environments (ML, SL, VG) allowed visualization of the influence of tidal variation in determining the spatial distribution pattern in relation to the diameter of the burrows. Keywords: Ocypode quadrata , Sandy beach, Burrow diameter, Praia do Forno, Arraial do Cabo.
All burrows with marks and evidence of the presence of the crab were counted in each transect and the diameters were measured (mm) with the aid of a europe mobile number list caliper. The SL area had a higher average number of burrows compared to ML and VG, with no significant difference found between ML and VG. In the distribution of burrows by average diameter, a significant difference was found between all environments, with the burrows found in VG being those with the largest diameter, followed by the burrows in SL, and later the ML with the smallest diameter, possibly due to the sensitive dehydration of individuals of smaller size of O.quadrata.
The work found that larger individuals look for vegetation to build their burrows, as they have better mobility and independence from the nearest aquatic environment than smaller individuals, having the ability to excavate deep burrows. Furthermore, the subdivision into three environments (ML, SL, VG) allowed visualization of the influence of tidal variation in determining the spatial distribution pattern in relation to the diameter of the burrows. Keywords: Ocypode quadrata , Sandy beach, Burrow diameter, Praia do Forno, Arraial do Cabo.