Biological characteristics of Pachygrapsus marmoratus in the southern Black Sea (Turkey)

Abstract

The present study was carried out to evaluate the biological characteristics of Pachygrapsus marmoratus in the southern Black Sea, Ordu, Turkey. A total of 1503 crabs, ranging from 0.9 to 4.3 cm in carapace length (CL), were collected monthly from November 2012 to October 2013. Female:male ratio was found to be 1:1. Measured male and female crabs were grouped in 0.49 cm CL class intervals. The mean CL, carapace width (CW) and weight (W) were determined as 2.55 ± 0.02 cm, 2.90 ± 0.02 cm and 14.21 ± 0.27 g, respectively, for all individuals. Correlation analysis was also conducted to reveal relationships between size parameters for males and females as well as between egg number and size. The b values of CW and W for male, female and ovigerous crabs were found to be 3.1, 3.06 and 2.95, respectively. Number of large-sized individuals and growth rate was higher in males compared to females.The highest correlation was found between CW and CL in both sexes. The mean condition index values were calculated as 49.03 for males and 45.79 for females. Ovigerous females were observed only from May to July 2013. The fecundity estimates ranged from 8989 to 151,578 eggs/crab, with an average value of 57,814.53 ± 3349 eggs/crab. The egg diameter ranged between 328.40 μm and 423.38 μm, with a mean size of 365.83 ± 1.97 μm. There was a positive relationship between egg number and female size.

Some biological characteristics of the marbled crab, Pachygrapsus marmoratus in the southern Black Sea (Sinop, Turkey)

“…Other studies gave also the similar results for b values as females (2.63) and males (2.87) with CW in Trabzon coasts of Turkey [11] and for females individuals 2.963 with CL in Ordu coasts of Turkey [12]. Also positive allometric growth was gave for males (b= 3.035) with CL and females (b=3.103), males (b= 3.065) individuals with CW [12]. The parameters of lengthweight relationship may be affected by various factors, such as period, temperature, food, environmental conditions, stomach fullness, differences in age, stage of maturity and sex [16].…”

“…Negative allometric growth (Pauly's t-test, P < 0.05) was observed for each of the sexes marbled crabs with CL. Other studies gave also the similar results for b values as females (2.63) and males (2.87) with CW in Trabzon coasts of Turkey [11] and for females individuals 2.963 with CL in Ordu coasts of Turkey [12]. Also positive allometric growth was gave for males (b= 3.035) with CL and females (b=3.103), males (b= 3.065) individuals with CW [12].…”

“…There were also strong correlations between W and CW-CL for females and males. In Ordu coasts of Turkey [12], the mean condition factors were gave as 49.03 for males and 45.79 for females. The highest monthly condition index (56.42) was recorded in March for males and (42.09) in May for females.…”

“…P. marmoratus is dominant intertidal brachyuran on the rocky Black Sea shore of Turkey, and its habitat includes the whole intertidal zone [9]- [10]. There are limited biological information about the species in this region [11]- [12]. In the present study, we described the size composition, sex rates, length-weight relationships as carapace length and carapace weight of P. marmoratus on the Black Sea coasts of Sinop, Turkey.…”

The trade-off between heat tolerance and metabolic cost drives the bimodal life strategy at the air-water interface

“…In addition, this species presents a convincing case study for the bimodal lifestyle because it shows a seasonal pattern of habitat selection. Generally, it inhabits the upper tidal belt where it is fully exposed to air during the summer season, whereas during the colder seasons, it usually moves into tidal pools or below the subtidal fringe by switching to a fully aquatic lifestyle 34 46 48 . These observations are further supported by the foraging behaviour of P. marmoratus , which feeds mainly on subtidal algae during the winter and on intertidal life forms during the warm spring and summer months 47 49 .…”