Abstract Knowledge of the fecundity of a species may facilitate the estimation of its reproductive potential and provide information regarding future stock size. Previous studies have shown variation in some reproductive parameters of Palaemon northropi, and we evaluated a new population to investigate the consistency and drivers of this variation. The objective of this study was to evaluate some reproductive characteristics of the shrimp P. northropi, from a population sampled on Me Ache Beach, in the municipality of Ilhéus, Bahia, Brazil. After sampling, carapace lengths were measured and embryonated eggs were removed, counted, weighed, and classified according to their stage of development. A total of 108 females were collected. The mean size of individuals was 6.2 ± 0.58 mm and the mean number of embryos per female was 234 ± 91 in developmental stage I and 195 ± 77 in developmental stage II. We found that the fecundity of P. northropi was influenced by the length of the carapace and the stage of embryo development, which we considered to indicate embryonated egg loss during incubation. The lack of correlation between reproductive investment and female size, suggests a stabilized investment pattern, likely reflecting an evolutionary trade-off between maximizing fecundity and the physical and energetic constraints imposed by the carapace volume and female survival. Ultimately, the consistent proportional allocation of energy underscores the species' resilience, showing how local selective pressures can mold reproductive traits to mitigate brood mortality in the intertidal zone.
Abstract This study focused on assessing the stock of crayfish, Pontastacus leptodactylus, which is a commercially valuable species in Türkiye's inland fisheries, within Hirfanlı Dam Lake, a key production site in the region. The research was conducted between June 2017 and May 2018 through monthly research surveys carried out at six different stations across the dam lake. The stock assessment process was conducted using the TropFishR package (v.1.6.3). A total of 5,920 crayfish were captured during the fishing trials, including 2,595 females and 3,325 males, with carapace lengths ranging from 19.65 mm to 81.14 mm. The “von Bertalanffy growth function” (VBGF) parameters K, L∞, and to were computed as 0.38 yr⁻¹, 84.72 mm (carapace length), and -0.24, respectively. The coefficients for total mortality (Z), natural mortality (M), and fishing mortality (F) were calculated as 1.86 yr⁻¹, 0.47 yr⁻¹, and 1.39 yr⁻¹, respectively. The values of E, Emax, E05, Fmax, and F05 were determined as 0.75, 0.64, 0.20, 1.16, and 0.36 respectively. Considering the biological reference points obtained, the stock can be considered overfished (F > Fmax). To ensure the sustainability of the crayfish stock in Hirfanlı Dam Lake at a target level of 0.40 “Spawning Potential Ratio” (SPR), the fishing mortality rate must be reduced to 0.54, which requires a 61.2% reduction in the current fishing pressure.
This study reports the first occurrence of Procambarus clarkii (Girard, 1852) in the Amazon biome, highlighting potential environmental risks. The introduction of animals beyond their original biogeographical boundaries, known as bio-invasion, poses significant threats to native biodiversity. These impacts arise through competition for natural resources and habitat, as well as the introduction of pathogenic organisms. The red swamp crayfish, P. clarkii, is a species native to North America that has been reported as invasive in Central and South America, Europe, Africa, and Asia. Its spread is likely due to biopiracy and the aquarium trade. In Brazil, P. clarkii has been documented as a non-native species in various states and biomes, particularly in the southern and southeastern regions. Two female specimens of P. clarkii were manually collected from a vegetated area near Cruzeiro Beach in the metropolitan region of Bel & eacute;m, Par & aacute;, Brazil. This area is notable for its tourism and its industrial and artisanal fishing activities. This finding marks the first documentation of P. clarkii in the Amazon biome and reinforce the need for further research to assess its potential ecological impacts on native aquatic species, in addition to possible underreporting of the occurrence of the species. Management recommendations are suggested to avoid introductions of P. clarkii in the region.
ABSTRACT The Macaronesia region, in the east Atlantic Ocean off the northwest coast of Africa, consists of five oceanic archipelagos and is known for its high levels of endemism. However, its terrestrial isopod fauna has received very uneven attention. In this study, we document five species newly recorded from the Macaronesia archipelagos: Ctenorillo atlanticus and Littorophiloscia culebrae in Cabo Verde; Porcellionides cingendus and Styloniscus spinosus in both the Azores and Madeira, and Trichorhina tomentosa in Madeira. Additionally, three new species are described: Miktoniscus atlanticus Cifuentes and Da Silva n. sp., and Trichoniscus furnaensis Cifuentes and Da Silva n. sp. from the Azores, and Soteriscus caboverdiensis Cifuentes and Da Silva n. sp. from Cabo Verde. This study also reports the first record of Armadilloniscus candidus on mainland Portugal. We compiled and updated the list of terrestrial isopod species recorded from the Macaronesia region to 120, with 60 endemic species, of which 71 belong to genera of Atlantic origin, including 46 endemic species. Furthermore, 34 species belong to genera of Mediterranean origin, of which eight are endemic, 14 species of tropical origin, of which six are endemic, and one species is of alpine origin. These patterns suggest this fauna shares a closer affinity with the Atlantic and Mediterranean faunas of Europe and North Africa than with the tropical fauna of Africa. The terrestrial isopod fauna of the Macaronesia region currently comprises 37 species in the Azores (three endemic), 16 species in Cabo Verde (four endemic), 63 species in the Canary Islands (28 endemic), 63 species in Madeira (25 endemic), and only three species are known from the Selvagens Islands.
Abstract The aim of the present study is to document a morphological abnormality in specimens of Macrobrachium amazonicum (Heller, 1862) based on specimens sampled in Jequitinhonha River, Bahia State, Brazil. Samples were collected at Itapebi Hydroelectric Power Plant using a cylindrical trap and a hand-drawn seine net. The morphologically altered telson was measured, characterized, and compared among specimens. Symmetrical or asymmetrical bifurcations were observed in the telson of four female specimens. Morphological abnormalities in decapod crustaceans can happen due to several reasons, and in M. amazonicum, it is mainly polluted rivers or failed wound healing; perhaps caused by excess fishing pressure in stocks bred in the dam reservoir. The present results add information about abnormalities in decapod crustaceans, besides being the second report on such features in this species.
