Body size is a crucial metric that is often obtained during the breeding migration of female land crabs. Most commonly, these measurements are obtained by hand but hand-measuring them carries risks for both crabs and researchers. In this study, we developed a novel “photo-image approach” to measure the maximum carapace width of Cardisoma carnifex (Herbst, 1796) in the field, and compared the results with hand measurements. We found a significant relationship in the maximum carapace width measured between the two approaches (Linear regression, , ). The difference (0.54 ± 0.18 mm) and relative error (0.61 ± 0.19%) in the maximum carapace width measured between the two approaches were minimal. We suggest that the photo-image approach is feasible for determining crab size in the field. The approach holds promise for its application in citizen science projects, facilitating advancements in crab research.
This present paper presents an inventory of benthic Malacostraca in the Gulf of Oran. The softbottom crustacean fauna was studied between February 2021 and September 2021. Samples were collected from 8 coastal stations. The class Malacostraca was represented with 2 subclasses, Eumalacostraca and Phyllocarida. Sixty-one species and 290 individuals belonging to seven crustacean orders (Amphipoda, Decapoda, Isopoda, Tanaidacea, Mysida, Lophogastrida and Leptostraca) were identified. Amphipoda were represented with the highest number of species (36) followed by Decapoda (11) and Isopoda (6). Tanaidacea and Mysida were poorly represented, with 3 and 2 species, respectively. Lophogastrida and Leptostraca were both represented by only one species. Among the crustaceans encountered, Ampelisca was the most dominant genus. The present inventory indicates that the carcinological fauna in the Gulf of Oran is less diversified than it is in other zones that have been studied on the Algerian coast (Gulf of Arzew, Bay of Bou-Ismail, and Bay of Algiers).
A new species of the wholly freshwater hymenosomatid crab genus Limnopilos Chuang & Ng, 1991, is described from Tonle Sap River in the lower Mekong drainage, Cambodia. This is the fourth species known, and the second one from Indochina. The type species, of Limnopilos, L. naiyanetri Chuang & Ng, 1991, was from the Chao Phraya drainage to the west in central Thailand. The new species is characterized by the presence of a rostrum, relatively shorter ambulatory legs and a different structure of the male first gonopod. Limnopilos sumatranus Naruse & Ng, 2007, is also recorded from southern Peninsular Malaysia for the first time.
Pseudotaeniacanthus japonicus sp. nov. (Taeniacanthidae) is described based on specimens of both sexes recovered from the body surface and the bucco-branchial cavity of the beach conger, Conger japonicus Bleeker, 1879 (Congridae) in Japan. C. japonicus represents a new host for the family. Copepodids V-III of the species are also described.
The green tiger shrimp, Penaeus semisulcatus, is a commercial species supporting important fishery along the Palk Bay coasts. It is a much sought-after seafood commodity influencing the livelihood of the local fishers. This study aims to investigate the fecundity of the species in relation to its morphometry. Fecundity is an index of reproductive capacity used to calculate a stock’s reproductive potential and the egg’s survival. The absolute fecundity of the shrimp ranged from 26 100 to 750 000 ova alive per female, and the mean absolute fecundity from 59 100 to 583 000 ova alive per female. The relationship between fecundity and the morphometric measurements showed a positive exponential correlation. One-way ANOVA indicated a significant difference in the different size classes’ carapace length, total weight, ovary weight, absolute fecundity, stomach weight, and gastrosomatic index. There was no significant difference between the relative fecundity and the gonadosomatic index. This study provides insight into the reproductive potential of P. semisulcatus for efficient management of the resource in Palk Bay, Tamil Nadu, India.
Mesocyclops leuckarti is a zooplankton that is potentially suitable as a live food for freshwater fish larvae. Aquaculture farmers often struggled to create nutritious live feed to maximize the production of larval fish. This study aimed to determine the effects of different enrichments on life-table parameters, protein, lipid and fatty acid content of M. leuckarti when enriched with different dietary enrichments. In this study, five treatments for raising the copepod were compared: rice bran, soybean meal, Chlorella sp., Spirulina sp., and unenriched (control). The results showed that M. leuckarti after 16 days of cultivation enriched with rice bran produced a higher population density (53.3 ind/ml) and survival rate (97.4%) than when cultivated with any of the other diets. In terms of nutritional value, protein content was higher in M. leuckarti enriched with rice bran (52% DW) and soybean meal (53% DW). However, lipid content was highest in M. leuckarti enriched with rice bran (14% DW). Fatty acids, such as α-linolenic acid ALA (7.21%) and docosahexaenoic acid DHA (6.26%) were higher in M. leuckarti enriched with rice bran. Eicosapentaenoic acid EPA (7.16%) and arachidonic acid ARA (7.74%) were higher in M. leuckarti enriched with Chlorella sp. This study suggests that organic by-products are better sources for strengthening and improving the growth performance and life history of this copepod, and possibly also of zooplankton organisms in general.
We analysed the mitochondrial genome of Aristaeopsis edwardsiana (Johnson, 1868) to understand its origin and evolution. Our study uncovered new insights into its phylogenetic relationships and evolutionary history. The mitogenome of A. edwardsiana is 15 913 bp, contains 37 genes, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNA) and 22 transfer RNA genes (tRNA). The AT content is 64.98%, with negative AT and GC skews. Our analysis showed that the PCGs of A. edwardsiana and related Aristeidae species underwent purifying selection. The tRNA genes exhibited a typical structure, except trnC and trnS1. The gene order was conserved compared to ancestral decapods. Using species of Dendrobranchiata, we constructed a phylogenetic tree, revealing the relationship of A. edwardsiana within the family Aristeidae. These findings improve our understanding of Decapoda classification and Aristeidae’s evolutionary position, facilitating further phylogenetic investigations. This study may serve as a valuable reference for future research on species of Aristeidae.