Variability in Carcinus maenas Fecundity Along Lagoons and Estuaries of the Portuguese Coast

Abstract

Although Carcinus maenas as a species is widely studied, research focusing on fecundity is still scarce. The main objective of this study was to evaluate size-fecundity relationships across different lagoons and estuaries, along the Portuguese coast, to understand how the local environment affects reproductive patterns. Between 2019 and 2020, ovigerous females were collected from the Southern (Ria Formosa and Ria de Alvor), Central (Rio Sado) and Northern regions (Ria de Aveiro) of Portugal, and the fecundity of each female was estimated by counting and weighing eggs. Morphometric relationships (carapace width–egg counting; egg counting–egg weight; body wet weight–egg weight; carapace width–body wet weight) were inferred from 180 egg-bearing females with a carapace width between 26.96 and 61.25 mm. A positive correlation between fecundity and the morphological parameters was observed. Differences in fecundity were found among all systems, from northern to southern Portugal, varying between 22121 and 408538 eggs per female. Furthermore, a regional gradient was observed across regions, with lower temperature estuaries (Ria de Aveiro) displaying an increase in fecundity. The fecundity in Rio Sado was also affected by salinity. Fecundity differences across regions were associated with hydrodynamics, temperature, and salinity differences among systems. No statistically significant differences were observed between Carapace Width—Body Wet Weight regressions performed in each studied system, indicating that, contrary to fecundity, the somatic growth of C. maenas is not affected by latitudinal or environmental conditions.

The population dynamics of Carcinus maenas (Crustacea: Portunoidea) in a coastal lagoon (Portugal, SW)

“…Ovigerous females were more abundant in this lagoon in the winter period, which has also been reported for other areas of the Portuguese Atlantic coast (Baeta et al 2005, Queiroga et al 1994. The estimated carapace width of females at maturity was 45.11 mm, which is lower than the sizes reported for North Wales or southwest Ireland (Reid et al 1997, Lyons et al 2012) and lower than the sizes reported for other Portuguese brackish water systems except the Sado estuary (Monteiro et al 2022).…”

Implications of Warming on the Morphometric and Reproductive Traits of the Green Crab, Carcinus maenas

“…This implies that populations from warmer locations can reproduce at smaller sizes at the cost of reaching smaller maximum sizes. This finding could be directly related to fecundity, given the close relationship between female size and the number of eggs [8,62]. Temperature also has an influence on egg size [71,72].…”

“…Carcinus maenas is an euryhaline intertidal species, adapted to live in a wide range of salinity and oxygen conditions [10] and thus inhabiting different systems (lagoons, estuaries, etc. ), with local conditions affecting populations biological traits [10,62]. Oxygen solubility increases as both salinity and temperature decrease [63], and, in a previous study [61], it was observed that the maximum size of crustacean species is influenced by oxygen availability.…”

“…The spawning period of aquatic species, including fish and crabs, is influenced by SST [66,67,73], as the optimal temperature range for spawning is extended in warmer conditions. This extended spawning period is made possible by the consistent maintenance of suitable temperatures [73], resulting in a continuous spawning period or even the occurrence of two reproductive periods in females in temperate water [62].…”

“…On the other hand, body size, size at maturity, larval duration, fecundity, and life span were all negatively related to SST, pointing in the opposite direction for the relationship between temperature and reproductive potential. It is worth noting that decreasing body size due to SST could affect fecundity and life span [10,62]. The duration of the egg-bearing period in females is expected to increase with the increase in SST, and the periods of reproduction will change from once to twice a year due to climate change, as happens in warmer water populations [74].…”