Iranian Journal of Fisheries Sciences 19(1) 518-524 2020 DOI: 10.22092/ijfs.2019.119311.0 Studying on relationship between carapace width and habitat properties of Tufted ghost crab (Ocypode cursor) living on Iztuzu beach–Turkey Yılmaz Ö.1*; Barlas M.2 Received: November 2016 Accepted: February 2016 1- Veterinary Department, Alaca Avni Çelik Vocational School, Hitit University, Turkey 2- Biology Department, Faculty of Science, Muğla Sıtkı Koçman University, Turkey *Corresponding author's Email: [email protected] Keywords: Iztuzu Beach, Ocypode cursor, Carapace width, Caught depth, Behavior model. Introduction permanent burrows which they The genus Ocypode is represented by protect along the coast (Brown and 21 species worldwide and the McLachlan, 2006). It was stated that distribution regions of these species burrows of ghost crabs can modify are the coasts of the Atlantic Ocean, the complexity of sandy beaches and the Mediterranean Sea, Eastern play an important role in Pacific Ocean and the Indo-Western productivity and in affecting their Pacific Ocean (Sakai and Türkay, physical environment. Ghost crab 2013). These crabs which have burrows may vary in architecture by Downloaded from jifro.ir at 12:42 +0330 on Sunday September 26th 2021 extensive dispersal along sandy-beach tidal changes and beach slope. For ecosystems are of high importance example, it was reported that in because of their roles as both India, J-, U- and Y- shaped burrows predators and beach scavengers to were found (Chan et al., 2006). The maintain the health of their habitats number of studies about the burrow (Wolcott, 1978; Brown and morphology of ghost crabs are scant McLachlan, 2006). When existence (Seike and Nara, 2008). of ocypodid crabs living on beaches From the results of observations was examined carefully and made in the field during the catch of comprehensively, it was determined ghost crabs found in burrows with that they possess the ability of being various morphologies, a behavior important indicator organisms for the model of Ocypode cursor was assessment of anthropogenic impacts realized and this model constituted on sandy beaches (Barros, 2001). the hypothesis of current study. Ocypodid crabs have terrestrial According to the hypothesis dispersal and they dig semi- proposed here, there is a negative 519 Yılmaz and Barlas, Testing behavior model for Ocypode cursor (Linnaeus, 1758) living on… correlation between the carapace Excel’07 and Statistica’7 to reveal the width and caught depth of O. statistical background. From the cursor. Considering this concept, the statistical results, standard deviation aim of this study was to values and correlation matrices were scientifically and statistically test the used to test the hypothesis of study. aspects which researchers should be aware of during the catch of ghost crabs – while less is known about their behavior patterns. Materials and methods Data, related to 244 ghost crabs’ (O. cursor) carapace width, distances of burrows from the sea and caught depth were collected from May 2014 Figure 1: Ocypode cursor. to May 2015 from İztuzu Beach which is 5 km long in southwestern Carapace width Turkey. Crab burrows were dug using Carapace width, which is the plastic shovels. Measurements of measure of the broadest part along crabs and distances were made using the line lying dorso-laterally on the a caliper with 0.02 mm sensitivity crabs’ carapace was used as the basic and a roller meter (50 m), parameter in determining the body respectively. During the field study, size of crabs. According to carapace both random sampling and catch- width, distribution of individual measure-release methods were numbers on the basis of gender was Downloaded from jifro.ir at 12:42 +0330 on Sunday September 26th 2021 applied. shown in Table 1. Also, minimum, Because O. cursor (Fig. 1) average, maximum and standard individuals have sexual dimorphism, deviation values were listed. It was data related to carapace width, seen that the number of individuals distances of burrows from the sea and was highest in the 20 and 29 mm caught depth were processed carapace width class of the sample separately for each gender. Recorded pool (females: 30 ind., males: 78 data were processed by MS Office ind.). Iranian Journal of Fisheries Sciences 19(1) 2020 520 Table 1: Distribution of individual numbers according to carapace width classes on the basis of genders (CW: carapace width, N: number of individuals, Std. Dev.: standard deviation). Genders CW (mm) N Min. (mm) Average (mm) Max. (mm) Std. Dev. < 10 3 6.84 7.5 8.16 0.660 10 - 19 11 15.32 18.17 19.76 1.219 Females 20 - 29 30 21.14 25.44 29.34 2.481 30 - 39 20 30.4 34.27 38.9 2.153 < 10 30 5.12 7.65 9.96 1.443 10 - 19 42 10.18 15.49 19.66 3.263 Males 20 - 29 78 20.18 25.16 29.88 2.681 30 - 39 29 30.02 32.83 37.72 2.164 40 - 49 1 40.52 40.52 40.52 - Results Distances of burrows from the sea that both genders of Ocypode cursor Distances of burrows from the sea is prefer to use the first 10 m band a parameter pointing to the distance landwards on İztuzu Beach. A from the center of the crab burrows decrease in digging burrow activity to the sea. Distribution of individual was recorded as ghost crab numbers on the basis of genders is individuals get farther from the sea. shown in Table 2. It was determined Table 2: Distribution of individual numbers according to the distances of burrows from the sea on the basis of genders (DBS: distances of burrows from Downloaded from jifro.ir at 12:42 +0330 on Sunday September 26th 2021 the sea). Genders DBS (m) N 1-4.9 37 5-9.9 26 Females 10-14.9 - 15-19.9 1 1-4.9 100 5-9.9 76 Males 10-14.9 3 15-19.9 1 Caught depth presents the number of individuals Caught depth is the measure of the recorded at different caught depth distance from the burrow aperture on classes on the basis of genders. the beach surface to the depth that While the highest numbers of ghost ghost crabs were caught. Table 3 crab individuals were determined 521 Yılmaz and Barlas, Testing behavior model for Ocypode cursor (Linnaeus, 1758) living on… from 35 cm depth (18 females and classes) were obtained from 5 and 10 46 males); the lowest numbers for cm depths. No females were sampled females (1 ind. for each depth from 5 and 10 cm depth classes and classes) were caught from 45 and 50 no males were sampled from 50 cm cm depths andthe lowest numbers for depth class. males (2 inds. for each depth Table 3: Number of individuals recorded at different caught depth classes on the basis of genders (CD: caught depth). Females Males CD (cm) 5 10 15 20 25 30 35 40 45 50 5 10 15 20 25 30 35 40 45 50 N - - 3 3 9 14 18 15 1 1 2 2 3 9 24 32 46 43 19 - Data associations correlation was found between Correlation matrices were used for carapace width and distances of the association of data. Carapace burrows from the sea and, between width, distances of burrows from the distances of burrows from the sea sea and caught depth parameters and caught depth; a negative were used to test the proposed correlation was found (r=-0.69 for hypothesis. females and r=-0.70 for males; With respect to Table 4, while no p<0.05) between carapace width and statistically significant (p<0.05) caught depth. Table 4: Pearson’s correlation matrix for carapace width, distances of burrows from the sea and caught depth on the basis of genders (p<0.05). Genders Females (N=64) Males (N=180) Downloaded from jifro.ir at 12:42 +0330 on Sunday September 26th 2021 Parameters CW CD DBS CW CD DBS CW 1.00 -0.69 -0.01 1.00 -0.70 0.10 CD 1.00 -0.23 1.00 -0.13 DBS 1.00 1.00 Ocypode cursor is a ghost crab In Table 5 and Fig. 2, which species with sexual dimorphism. represents females, it was seen that Thus, instead of considering data in the 40 cm caught depth class is the a pooled form, separated analysis for richest in that it includes individuals each gender was suggested to infer of ifferent carapace widths. However the role of gender in the hypothesis. this depth class involves fewer crabs To this end the distribution of when compared with the 35 cm depth individual numbers in caught depth class. Also, it was determined that classes, according to the carapace crabs smaller than 10 mm were width classes of females and males caught deeper than those larger than is presented in Tables 5 and 6. 30 mm. Crab individuals larger than Iranian Journal of Fisheries Sciences 19(1) 2020 522 30 mm in carapace width were beach surface. observed relatively closer to the Table 5: Distribution of female individual numbers according to carapace width and caught depth classes. CD (cm) CW (mm) 5 10 15 20 25 30 35 40 45 50 < 10 - - - - - - - 1 1 1 10 - 19 - - - - - - 3 8 - - 20 - 29 - - - 1 1 13 11 4 - - 30 - 39 - - 3 2 8 1 4 2 - - 40 - 49 - - - - - - - - - - In Table 6 and (Fig. 2), representing pattern with females, males smaller males, it was shown that the 25 and than 10 mm were caught from a 35 cm depth classes are richest in deeper portion of their burrows individuals of different carapace whereas crabs larger than 30 mm width classes.