Comparison of the Dynamics between Coastal and Midshore Populations of Pinctada radiata (Leach, 1814) (Mollusca: Bivalvia) in the Gulf of Gabes, Tunisia

Abstract

Pinctada radiata is the first lessepsian bivalve in the Mediterranean Sea where it has been progressively expanding westwards. This comparative study provides the first insight into the population dynamics of the species by investigating the population structure, growth, mortality, and exploitation status in the coastal zone (site A; 0-1 m) and midshore area (site B; 14 m depth). The results showed that the asymptotic shell length was smaller in the coastal zone (L∞ = 78.75 mm) compared to that in the midshore station (L∞ = 105 mm). Growth coefficient (K) was higher in site A (1.70 yr-1) than in site B (0.66 yr-1). Growth performance index (Φ') values were almost similar (4.023 and 3.862) in both pearl oysters stocks. The theoretical maximum age (Tmax) was smaller in site A (2.66 yr-1) than in site B (7.05 yr-1). Total mortality (Z) was estimated by length-converted catch curve at 6.18 and 1.62 yr-1 , fishing mortality (F) at 4.43 and 0.78 yr-1 and natural mortality (M) at 1.75 and 0.83 yr-1 for site A and site B, respectively. Recruitment was continuous and showed two major pulses in the two sampling sites.

Hazardous impacts of heavy metal pollution on biometric and biochemical composition of pearl oyster Pinctada radiata from five sites along Alexandria coast, with reference to its potential health risk assessment

“…The b values were significantly less than unity ( p < 0.001; Student’s t -test) (Table 5 ), indicating that TW increased relatively slower than SH, SL, and THK. These results aligned with previous findings of negative allometry relationships in P. radiata , regarding TW-SL (Derbali et al 2019 ) and TW-SH (Moutopoulos et al 2021 ). Negative allometry has also been reported in various Pinctada spp., including P. fucata , P. margaritifera , and P. sugillata (Lim et al 2020 ).…”

Endemic Muar, Malaysia Oyster Crassostrea (Magallana) saidii Wong & Sigwart, 2021 Approaches Optimal Harvest Despite Year-Round Multiple Recruitments

“…The annual growth rate (K) was recorded at 0.30 for the oyster C. tulipa (Osei et al, 2021) in Densu Delta, Ghana, and the value was observed at 3.96 for the oyster C. rhizophorae in the waters of Venezuela (Angell, 1986). These variations in the growth parameters can be explained by the different species or the environmental factors present in various study areas (Derbali et al, 2020).…”