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Signal theory predicts organisms should evolve signals that are conspicuous to intended receivers in natural signalling environments. Cleaner shrimps remove ectoparasites from reef fish clients and many signal their intent to clean by whipping long, white antennae. As white is a reliably conspicuous colour in aquatic environments, we hypothesized that selection has acted to increase broad-spectrum antennal reflectance in cleaners. Using scanning electron microscopy, optical models and reflectance measurements, we found that the antennae in three obligate cleaner species from two families (Palaemonidae and Lysmatidae) had thick (∼6 µm) chitinous layers or densely packed high refractive index spheres (300-400 nm diameter), which models show increase reflectance (400-700 nm). Two facultative and non-cleaning species had no visible antennae ultrastructure beyond the chitinous exoskeleton. Antennae reflectance was significantly higher in obligate cleaners than in facultative and non-cleaning species. Our results suggest that some obligate cleaners may have evolved ultrastructures that increase the conspicuousness of their antennae as signals.

Macrobrachium amazonicum (Heller, 1862) is a freshwater prawn species subject to high commercial exploitation in northern Brazil, with wide geographic distribution and high phenotypic plasticity. This study aimed to assess the natural diet of an M. amazonicum population from Rio Grande, comparing consumed items with differences according to sex, seasons, and habitat food availability. The prawns were collected monthly between September 2018 and August 2019. A total of 348 stomachs were examined, and their content evaluated based on degree of repletion, the point method, and frequency of occurrence. Food preferences were also determined. Seven food types were recorded in the stomachs of M. amazonicum, including microplastics. No significant differences were observed in the diet between males and females or across different seasons. The species exhibited no food preference in its diet. The findings confirm an omnivorous diet for M. amazonicum and suggest that the composition and proportion of dietary items may depend on their availability in the environment. The presence of microplastics in the analyzed stomachs raises concern as it indicates contamination in the aquatic environment resulting from unsustainable human activities. [ABSTRACT FROM AUTHOR]

Our work provides a checklist of freshwater decapods (Brachyura and Caridea) from the Parnaíba river basin, Brazil, based on field collections carried out between 2018 and 2020. Eight species were collected at 30 sampling sites in the main river channels, streams, and ponds throughout the upper, middle, and lower regions of the Parnaíba river basin. The species of shrimp reported herein are Atya gabonensis (Gibiel, 1875) (Atyidae), Macrobrachium amazonicum (Heller, 1862), Macrobrachium brasiliense (Heller, 1862), Macrobrachium jelskii (Miers, 1778), and Macrobrachium olfersii (Wiegmann, 1836) (Palaemonidae), while crab species reported are Goyazana castelnaui (H. Milne-Edwards, 1853), Sylviocarcinus pictus (H. Milne-Edwards, 1853) (Trichodactylidae), and Kingsleya parnaiba Pralon, Pinheiro & Santana, 2020 (Pseudothelphusidae). The record of Macrobrachium brasiliense is the first for the Parnaíba river basin. The knowledge of the diversity of freshwater decapod fauna can contribute to the conservation of species and their habitats.

Periclimenes brevicarpalis is widely distributed in the Indo West Pacific oceans. The mitochondrial genome of P. brevicarpalis was sequenced and assembled firstly by next generation sequencing technology in our study. The complete mitochondrial genome of P. brevicarpalis was 16,673 bp in size, consisted of 22 transfer RNA genes, 13 protein coding genes and two ribosomal RNA genes. The contents of the four bases were C (25.62%), T (28.73%), A (31.64%), and G (14.01%). The result of phylogenetic analysis showed that P. brevicarpaliswas clustered with Anchistus australis. In conclusion, our research provided valuable data for phylogenetic analysis of the Palaemonidae family as the first report about mitochondrial genomes in Periclimenes.

Periclimenes brevicarpalis is widely distributed in the Indo West Pacific oceans. The mitochondrial genome of P. brevicarpalis was sequenced and assembled firstly by next generation sequencing technology in our study. The complete mitochondrial genome of P. brevicarpalis was 16,673 bp in size, consisted of 22 transfer RNA genes, 13 protein coding genes and two ribosomal RNA genes. The contents of the four bases were C (25.62%), T (28.73%), A (31.64%), and G (14.01%). The result of phylogenetic analysis showed that P. brevicarpaliswas clustered with Anchistus australis. In conclusion, our research provided valuable data for phylogenetic analysis of the Palaemonidae family as the first report about mitochondrial genomes in Periclimenes. [ABSTRACT FROM AUTHOR]

A freshwater prawn M. sundaicum, is an obligate species to acidic peat swamp. Up to the present, M. sundaicum has only been reported in the West Kalimantan, the Riau Archipelago, and Jambi Provinces in Indonesia. The aim of this research is to determine the distribution and habitat preferences of peat swamp prawn in Selat Panjang Island, Riau Province, Indonesia. The samples were collected in seven peat swamp rivers by hand net. The study yielded one hundred specimens. The acidic peat swamp is a perfect habitat for M. sundaicum. This study provided the basic information about peat swamp prawn in Selat Panjang Island, especially their distribution and habitat preferences. [ABSTRACT FROM AUTHOR]

Context: Macrobrachium amazonicum is a freshwater prawn of socioeconomic importance in the Amazon region, whose growth, reproduction and fecundity vary according to the environment. Aims: To determine which abiotic factors influence the size and fecundity of populations of M. amazonicum in estuary and river environments. Methods: To do so, we captured a total of 255 ovigerous females, 181 from the estuary and 74 from the river, and measured temperature, total dissolved solids, turbidity, salinity, pH, dissolved oxygen and precipitation. Key results: We found that turbidity, precipitation and dissolved oxygen explained the variation in M. amazonicum size, and that the estuarine females were larger and had more and smaller eggs than riverine females. Conclusions: Precipitation, turbidity and dissolved oxygen were found to bedetermining factors for the ecological plasticity of M. amazonicum females in different environments. Implications: Freshwater prawn species display different reproductive strategies for distinct environments, and understanding their fecundity is important to establish efficient management policies. In addition, this information should be useful to improve the cost–benefit ratio of freshwater prawn farming in the Amazon region. In this study, we sought to determine which abiotic factors influence the fecundity and size of populations of M. amazonicum in estuary and river environments. Precipitation, turbidity and dissolved oxygen are determining factors for the differences found in the fecundity and size of M. amazonicum females in different environments. This information should be useful for improving the cost-efficiency of prawn culture. (Image credit: Breno Silva and Juan Caldas.) [ABSTRACT FROM AUTHOR]

The availability of resources for aquafeed production is one of the main constraints that could hinder the rapid expansion of aquaculture. Our aim was to investigate the inclusion of spent brewer's yeast as an ingredient in aquafeeds and evaluate the zootechnical performance, proximate and elemental body composition, amino acid profile, and egg development of the freshwater prawn Macrobrachium borellii. We fed juvenile prawns with three feeds: D18, D25, and D32, which represent 18%, 25%, and 32% inclusion of SBY as a partial substitute for FM, respectively, during a 75-day trial. Prawns cultivated with D18 exhibited higher growth increment (97.73 ± 7.30%), specific growth rate (0.39 ± 0.02%), and protein efficiency ratio (0.27 ± 0.04%) than other treatments. However, the total biomass produced, as well as the proximate and elemental body composition of prawns, was similar across treatments. The most abundant essential amino acids in the prawn's body were arginine, leucine, and lysine while feeds showed good quality despite the limitations of arginine and phenylalanine. We observed successful hatching when prawns were fed with feed containing more SBY, indicating a more successful reproductive stock. Farming prawns with feeds containing different inclusion percentages of SBY is feasible. The inclusion of this raw material in high replacement percentages (up to 50%) is viable and could promote the bioeconomy by utilizing discarded local raw material instead of wild-caught resources. [ABSTRACT FROM AUTHOR]

The pantropical genus Palaemonella Dana, 1852 (Caridea: Palaemonidae) currently includes 27 species of free-living and symbiotic marine shrimps. The monophyly of Palaemonella with respect to several closely related genera, however, has been questioned by recent analyses. We tested the monophyly of Palaemonella based on multigene phylogenetic analysis and the genus was revealed to be a paraphyletic assemblage by inclusion of species of the genera Eupontonia Bruce, 1971 and Vir Holthuis, 1952, and two genetic lineages of the western Atlantic Cuapetes americanus (Kingsley, 1878). We recognise one of the latter lineages as the previously described Periclimenes rhizophorae Lebour, 1949. Eupontonia and Vir are synonymised with Palaemonella. We also transfer Cuapetes americanus and Periclimenes rhizophorae to Palaemonella. Species previously assigned to Vir were revised; V. colemani Bruce, 2003, V. orientalis (Dana, 1852), V. philippinensis Bruce & Svoboda, 1984 and V. smiti Fransen & Holthuis, 2007 are regarded as valid species of Palaemonella; Vir longidactylus Marin, 2008 is synonymised with P. smiti; and the status of V. euphyllius Marin & Anker, 2005 remains unresolved. Palaemonella is currently regarded as a taxon with variable states of two main diagnostic characters, i.e. the plesiomorphic mandibular palp (fully reduced in P. americana) and the hepatic tooth (fully reduced in former species of Vir and Eupontonia - evidently due to symbiotic modes of life). [ABSTRACT FROM AUTHOR]

The caridean shrimps comprise one of the largest groups of amphidromous species, sharing their life cycle between freshwater habitats and the ocean. Key species of tropical ecosystems, some of which are also targets for local or international markets without any regulations being implemented, make carideans particularly vulnerable to the threats facing natural populations. We present an inventory of amphidromous carideans and an overview of their habitats, the interests they arouse, because of their ecological role as well as for their commercial importance and the threats they face. We suggest directions for future research following an experimental-biology approach, that may help to assess risks and impacts on natural habitats and ultimately prioritize conservation and management projects. [ABSTRACT FROM AUTHOR]

Contamination by polycyclic aromatic hydrocarbons (PAH) in freshwater ecosystems represents a serious environmental problem. When they enter the water, either by oil spills or industrial discharges, they adhere to suspended particles, accumulating in sediments and causing them to be absorbed by aquatic organisms, such as decapods and amphipods. Therefore, to evaluate the effects of PAHs on Macrobrachium borelli and Hyalella azteca, a bibliographic compilation was made considering the axes of hydrocarbon toxicity and adaptation mechanisms for these pollutants. The results for decapods indicate a high toxicity for the water-soluble fraction with diesel, although this does not prevent normal hatching of eggs. For amphipods, it was found that, according to their mortality, it is a more sensitive species than other organisms, such as chironomids. In addition, the sublethal effects due to PAH exposure vary in the affectation in the size and behavior of the organism, as well as DNA damage. Finally, the adaptive mechanisms it possesses are not considered effective for the survival of the species. [ABSTRACT FROM AUTHOR]

For the first time, a Pinna shell associated shrimp Ensiger custos was documented from the shallow seagrass beds of Palk Bay, India. The shrimp specimen was identified based on the morphological characteristics such as chela of the first pereiopod cannulate, absence of distal teeth on the rostrum, antennal spine minute and dactylus of the second pereiopod with single large triangular tooth in the proximal half. The E. custos was found to be closely related to E. custoides. In the present study, E. custos shrimp was found associated with Pinna bicolor Gmelin 1971. [ABSTRACT FROM AUTHOR]

A new shrimp species of the genus Periclimenes is described based on specimens collected in the Bissagos Islands, Guinea-Bissau. Specimens were collected from an unidentified octocoral. This is the ninth species in the genus known to be from the East Atlantic and Mediterranean. [ABSTRACT FROM AUTHOR]

The diversity and evolution of the Red Sea invertebrates in mesophotic and deep-water benthic ecosystems remain largely unexplored. The Palaemonidae is a diversified family of caridean shrimps with numerous taxa in need of taxonomic revisions based on recent molecular analyses. The Red Sea mesophotic and bathyal palaemonid shrimps are largely unstudied. During recent expeditions off the Red Sea coast of Saudi Arabia, several palaemonid specimens were collected at a depth range of 88–494 m, spanning the mesophotic and bathyal zones. This material was examined morphologically and genetically to infer phylogenetic relationships among the Red Sea taxa and several other palaemonid genera. The concordant morphological and genetic data led to the description of two new genera and two new species. Moreover, one species was recorded in the Red Sea for the first time, with a new host record, whereas three further deep-water species, which do not occur in the Red Sea, were formally transferred to a different genus. As more exploration efforts are deployed, research on the diversity and evolutionary relationships among marine invertebrates from the Red Sea will further underline the uniqueness of its mesophotic and bathyal fauna. [ABSTRACT FROM AUTHOR]

Durante o período de cheia, abril e maio de 2021, foram coletados 122 camarões: 104 da família Palaemonidae e 18 da Euryrhynchidae. E 18 caranguejos da família Trichodactylidae: 8 do gênero Sylviocarcinus e 10 do Valdivia. As coletas foram realizadas em seis pontos no baixo rio Branco, dentro e fora da “Estação Ecológica do Niquiá.” Em cada ponto a amostragem foi de 4 horas: nas áreas de inundação, macrófitas aquáticas, raízes e gramíneas submersas, praias, margens das barrancas e serrapilheira submersa. Para captura dos crustáceos foram utilizadas armadilhas de espera tipo covo, matapi, puçás e armadilhas confeccionadas com garrafas “pet” de dois litros. Os crustáceos capturados foram transportados para o “Laboratório de Organismos Aquáticos da Amazônia (LOAM/EMBRAPA)”, em Boa Vista onde foram identificados e depositados na coleção. Foram identificadas seis espécies de camarões: Macrobrachium brasiliense; M. nattereri; M. ferreirai; Pseudopalaemon chryseus; Palaemon yuna e Euryrhynchus amazoniensis; e duas espécies de caranguejos: Sylviocarcinus pictus e Valdivia serrata.

The aim of this work was to evaluate the spatial and temporal distribution of shrimp species in the Lake Nokoué-Cotonou Channel complex for an efficient management of the fishery. The results of one year sampling from five stations (North, South, East, Central and West) in the complex revealed the following proportions: Penaeus notialis 73.68%, Macrobrachium macrobrachion 13.81%, Macrobrachium vollenhovenii 5.36%, Penaeus monodon 2.68%, Macrobrachium felicinum 2.20%, Penaeus kerathurus 1.72%, Macrobrachium cf. zariquieyi 0.27%, and Macrobrachium equidens 0.27%. The species M. cf. zariquieyi and M. equidens were never reported from Benin, but are now found in Lake Nokoué. Spatially, Penaeus (Penaeus notialis) are more abundant in the west (Acadja concentration zone), while Macrobrachium (Macrobrachium macrobrachion) are more dominant in the east (near the Ouémé entrance) and north (near the Sô entrance) of the lake. Penaeus are strongly present in the lagoon complex from January to August, while Macrobrachium are more abundant in Lake Nokoué from September to December. Spearman's correlation analysis revealed that increasing salinity, pH, transparency and total dissolved solids (TDS) positively influenced the abundance of P. notialis , while increasing salinity, pH, transparency, and TDS negatively influenced the abundance of M. macrobrachion at the 5% significance level. For an efficient management of the shrimp fishery, it is desirable that the shrimp fishery in Lake Nokoué, mainly in the Cotonou Channel, which is a very sensitive area for their seasonal migrations, benefits from at least three months of respite per year, from November to January. This period corresponds to the strong migration of juvenile Penaeus towards the lake. This should allow many Penaeus to grow up and breed at least once in their lives, according to the species' life cycle presented. [ABSTRACT FROM AUTHOR]

To further understand the origin and evolution of Palaemonidae (Decapoda: Caridea), we determined the mitochondrial genome sequence of Palaemon macrodactylus and Palaemon tenuidactylus. The entire mitochondrial genome sequences of these two Palaemon species encompassed 37 typical genes, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs), and a control region (CR). The lengths of their mitochondrial genomes were 15,744 bp (P. macrodactylus) and 15,735 bp (P. tenuidactylus), respectively. We analyzed their genomic features and structural functions. In comparison with the ancestral Decapoda, these two newly sequenced Palaemon species exhibited a translocation event, where the gene order was trnK-trnD instead of trnD-trnK. Based on phylogenetic analysis constructed from 13 PCGs, the 12 families from Caridea can be divided into four major clades. Furthermore, it was revealed that Alpheidae and Palaemonidae formed sister groups, supporting the monophyly of various families within Caridea. These findings highlight the significant gene rearrangements within Palaemonidae and provide valuable evidence for the phylogenetic relationships within Caridea. [ABSTRACT FROM AUTHOR]

Two new species of the genus Onycocaris are described, based on single specimens from Fiji and Moorea respectively. Onycocaris iti sp. nov. is closely related to the relatively widespread species, O. seychellensis Bruce, 1971; whilst O. brucei sp. nov. is a pseudo-cryptic species allied to O. quadratophthalma (Balss, 1921). [ABSTRACT FROM AUTHOR]

A new species of Palaemonella , P. sandyi sp. nov., is described on the basis of specimens collected in association with euphylliid scleractinian corals, Euphyllia glabrescens and E. cristata. Material was collected from the Maldives, Cebu in the Philippines, Semporna in Malaysia, and from Java, Bali, Sulawesi, Kalimantan, Ternate and Raja Ampat in Indonesia. The new species is similar to P. colemani and P. euphyllius , which are associated with euphylliid corals of the genus Fimbriaphyllia. The new species can be distinguished from P. colemani and P. euphyllius , as well as from the species P. philippinensis and P. smiti , which are both symbionts with plerogyrid scleractinians, on the basis of morphological characters in the rostrum and ambulatory pereiopods, colouration, and molecular data. [ABSTRACT FROM AUTHOR]

The present study analyzed the presence of microplastics (MPs) in the shrimp Macrobrachium amazonicum, which is an economically important food that is consumed in several regions of the Brazilian Amazon. A total of 600 specimens of M. amazonicum were captured at two sampling sites (urban and rural area). A total of 2597 MP particles were recorded in the shrimps, with a significant difference between the two sites. The presence of MPs in the body parts also differed significantly. No significant difference was found between MPs abundance and sex of the shrimps. The size of the MPs did not differ significantly between the collection sites and between the body parts. Dark blue fiber–type MPs were the most abundant. A positive correlation was observed between the abundance of MPs and the total weight of shrimps. Raman spectroscopy identified the dark blue fibers as polypropylene and the FTIR technique identified the light blue fragments as nylon. The results indicate that the presence of MPs in the M. amazonicum shrimp is associated with the capture sites near the urban area and is present in the diet of the Amazonian population that regularly consumes this crustacean in traditional dishes. [ABSTRACT FROM AUTHOR]

A single specimen of Pontonides sibogae was collected from a dendrophylliid coral by trimix SCUBA diving at a depth of 75 m during fieldwork around Jejudo Island, Korea in 2020. The morphology of the specimen corresponds closely to the main diagnostic characters of the holotype, especially in the presence of a distinct tubercle on the eyestalk, as well as the second pereiopod with fusiform setae along the dorsal border of the ischium.The genus Pontonides had previously not been reported from Korean waters. Herein, colour photographs are provided, as well as an illustrated description including previously unreported characteristics.

Mimicry of warning signals is common, and can be mutualistic when mimetic species harbour equal levels of defence (Müllerian), or parasitic when mimics are undefended but still gain protection from their resemblance to the model (Batesian). However, whether chemically defended mimics should be similar in terms of toxicity (i.e. causing damage to the consumer) and/or unpalatability (i.e. distasteful to consumer) is unclear and in many studies remains undifferentiated. In this study, we investigated the evolution of visual signals and chemical defences in a putative mimicry ring of nudibranch molluscs. First, we demonstrated that the appearance of a group of red spotted nudibranchs molluscs was similar from the perspective of potential fish predators using visual modelling and pattern analysis. Second, using phylogenetic reconstruction, we demonstrated that this colour pattern has evolved multiple times in distantly related individuals. Third, we showed that these nudibranchs contained different chemical profiles used for defensive purposes. Finally, we demonstrated that although levels of distastefulness towards Palaemon shrimp remained relatively constant between species, toxicity levels towards brine shrimp varied significantly. We highlight the need to disentangle toxicity and taste when considering chemical defences in aposematic and mimetic species, and discuss the implications for aposematic and mimicry signal evolution.

Cleaner shrimp and their reef fish clients are an interspecific mutualistic interaction that is thought to be mediated by signals, and a useful system for studying the dynamics of interspecific signalling. To demonstrate signalling, one must show that purported signals at minimum (a) result in a consistent state change in the receiver and (b) contain reliable information about the sender's intrinsic state or future behaviour. Additionally, signals must be perceptible by receivers. Here, we document fundamental attributes of the signalling system between the cleaner shrimp Ancylomenes pedersoni and its clients. First, we use sequential analysis of in situ behavioural interactions to show that cleaner antenna whipping reliably predicts subsequent cleaning. If shrimp do not signal via antenna whipping, clients triple their likelihood of being cleaned by adopting darker coloration over a matter of seconds, consistent with dark colour change signalling that clients want cleaning. Using experimental manipulations, we found that visual stimuli are sufficient to elicit antenna whipping, and that shrimp are more likely to 'clean' dark than light visual stimuli. Lastly, we show that antenna whipping and colour change are perceptible when accounting for the intended receiver's visual acuity and spectral sensitivity, which differ markedly between cleaners and clients. Our results show that signalling by both cleaners and clients can initiate and mediate their mutualistic interaction.

Cryphiops caementarius is an amphidromous freshwater prawn endemic to the basins of Peru and northern Chile, where its populations are strongly threatened by hydric and fishing overexploitation. Mortalities of C. caementarius caused by canalization and water extraction in the Choapa River Basin are reported during March 2020 in Tunga Norte (⁓250 specimens) and January 2021 in Limahuida (⁓300 specimens). This situation was also reported in other basins in the Semiarid north of Chile during 2014 and 2018. These changes are related to the water crisis facing this country zone and reflects a mismatching in the water management in the face of the socio-economic development and native species conservation. [ABSTRACT FROM AUTHOR]

Shrimp Palaemon macrodactylus Rathbun, 1902 of East Asian origin has successfully naturalized in the Taganrog Bay of the Sea of Azov and is currently entering the Lower Don, where it is currently found in large quantities. The species was first recorded for the eastern part of the Sea of Azov; there is a specimen collected in 2016 among the collection material. The found individuals with eggs indicate that P. macrodactylus formed a self-reproducing population in the Don delta and the eastern part of the Taganrog Bay. [ABSTRACT FROM AUTHOR]

When improving the water quality of natural bodies such as lakes, the explosive growth of filamentous green alga Cladophora can limit the growth of submerged macrophytes and prevent the water from shifting to a clear state. During the decay of Cladophora, it can cause various water quality issues such as reduced dissolved oxygen, increased nutrient levels and water odor. Biomanipulation, involving the introduction of a suitable density of aquatic animals into the water, can reduce the biomass of filamentous algae. We hypothesized that stocking appropriate densities of aquatic animals could reduce filamentous algal biomass and at the same time reduce the concentration of odorants in the water. Our study investigated the impact of stocking swamp shrimp (Macrobrachium nipponense), rosy bitterling (Rhodeus ocellatus), and silver carp (Hypophthalmichthys molitrix) at low (30 g/m 3 ), medium (60 g/m 3 ) and high (120 g/m 3 ) densities on water quality, biomass of primary producers (such as Cladophora, submerged macrophyte and algae) and malodorous volatile organic sulfur compound dimethyl sulfide (DMS) in the water, respectively. It was found that the swamp shrimp treatment groups and the rosy bitterling high-density groups effectively inhibited the growth of filamentous green algae cover, in which the rosy bitterling high-density group reduced the filamentous green algae mat coverage by 29.65 % compared with the control group. Additionally, the high-density swamp shrimp and rosy bitterling groups notably promoted the growth of submerged macrophytes (Vallisneria denseserrulata), and significantly reduced the concentration of the malodorous DMS in the water. Overall, stocking swamp shrimp and rosy bitterling can benefit the restoration of aquatic ecology and the maintenance of clear water. However, it is essential to consider potential changes in water quality resulting from excessive stocking density. Therefore, the appropriate density and proportion of stocking should be determined in conjunction with the specific scale of the aquatic ecological restoration project., Competing Interests: Declaration of competing interest All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microplastics (MPs) pose a significant threat to marine ecosystems, necessitating robust biomonitoring to assess aquatic risks and inform effective policymaking. In this study we investigated MPs pollution in gammarus (Pontogammarus maeoticus), shrimp (Palaemon elegans), sediment and water samples of southern coast of the Caspian Sea to assess the potential use of these two crustaceans as biomonitors of MPs pollution, bioconcentration of MPs in organisms' tissue and the pollution risks of MPs in environmental matrices. Samples were collected from 6 stations during June to August 2023. MPs were found in all compartments with an average of 100 ± 45.34 items/kg dry weight, 0.45 ± 0.06 items/L, 0.38 ± 0.21 items/individual or 0.58 ± 0.34 items/g wet weight (ww) and 0.26 ± 0.15 items/individual or 8.69 ± 7.88 items/g ww, for sediments, seawaters, P. elegans and P. maeoticus, respectively. MPs were prevailed by class 300-1000 μm in size, polyamide in polymer, fiber in shape and black in color. P. maeoticus and P. elegans did not meet the selection criteria as MPs biomonitors. However, bioconcentration factor (BCF) illustrated that both crustaceans can absorb and accumulate MPs from their surrounding water (BCF >1). Based on contamination factors (CF) values, sampling stations were polluted with MPs (1 ≤ CF < 6). The overall pollution load index (PLI) for sediment and seawater stations were 2.47 and 1.88, respectively, indicating minor contamination with MPs in the risk level I. Current research provides useful information on MPs pollution in crustaceans species and the risk level of MPs in environmental matrices that can be suitable for bioaccumulation hazard assessment and future monitoring programs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The impact of invasive alien species on native communities can act at different levels both by affecting the ecosystem's structure (i.e., mainly in the case of vegetation) and through direct interactions (i.e., competition for food or space). Behavioral studies under controlled conditions can provide relevant information on both the invasive potential of alien species and the potential impact of the invaders on the local native species. In the laboratory, the competition for food resources between the invasive oriental shrimp Palaemon macrodactylus, Rathbun, 1902, and the Mediterranean native shrimp Palaemon elegans, Rathke, 1836, was analyzed. These species are typical residents of coastal transitional and estuarine waters, so the experiments were carried out using two salinity conditions that characterize the coastal lagoon of Venice. Although at both salinity treatments the alien species tended to be more aggressive than the native one, significant differences between the two species were mainly observed at a salinity of 30. In particular, at a salinity of 30, P. macrodactylus spent more time attending to the food source than the native species. The results are discussed in light of the potential inter-specific competition between the two species within the conditions of the Venice lagoon. [ABSTRACT FROM AUTHOR]

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Dams have long been associated with elevated burdens of human schistosomiasis, but how dams increase disease is not always clear, in part because dams have many ecological and socio-economic effects. A recent hypothesis argues that dams block reproduction of the migratory river prawns that eat the snail hosts of schistosomiasis. In the Senegal River Basin, there is evidence that prawn populations declined and schistosomiasis increased after completion of the Diama Dam. Restoring prawns to a water-access site upstream of the dam reduced snail density and reinfection rates in people. However, whether a similar cascade of effects (from dams to prawns to snails to human schistosomiasis) occurs elsewhere is unknown. Here, we examine large dams worldwide and identify where their catchments intersect with endemic schistosomiasis and the historical habitat ranges of large, migratory Macrobrachium spp. prawns. River prawn habitats are widespread, and we estimate that 277-385 million people live within schistosomiasis-endemic regions where river prawns are or were present (out of the 800 million people who are at risk of schistosomiasis). Using a published repository of schistosomiasis studies in sub-Saharan Africa, we compared infection before and after the construction of 14 large dams for people living in: (i) upstream catchments within historical habitats of native prawns, (ii) comparable undammed watersheds, and (iii) dammed catchments beyond the historical reach of migratory prawns. Damming was followed by greater increases in schistosomiasis within prawn habitats than outside prawn habitats. We estimate that one third to one half of the global population-at-risk of schistosomiasis could benefit from restoration of native prawns. Because dams block prawn migrations, our results suggest that prawn extirpation contributes to the sharp increase of schistosomiasis after damming, and points to prawn restoration as an ecological solution for reducing human disease.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.

This study investigates the distribution, growth, and reproduction of the fluvial, regional, and vulnerable species, Macrobrachium shokitai, on Iriomote Island in southwestern Japan. Prawns were captured at seven stations along a small, 4.0-km-long river, among ca. 40 rivers on the island. Animals were collected monthly during 2019 and abundance, carapace length (CL), sex, and the presence or absence of eggs attached to pleopods were documented. Prawns were primarily collected at stations >2.7 km above the river mouth at >270 m elevation. Stable, dense populations were observed above the waterfall. The sex ratio was significantly female-biased between January and August. Later in the year the ratio was 1 : 1. A bimodal CL distribution was recorded; with the emergence of larger individuals in some months. Lifespan appeared to be >1 year. Recruits, including several juvenile instars, were found between August and December. Ovigerous females were encountered from April to October but were more abundant from June to August. The phenology and duration of the breeding season were consistent with generic characteristics of the genus throughout subtropical and temperate East Asia. [ABSTRACT FROM AUTHOR]

The mainland of Sulawesi is well known for its high diversity of freshwater shrimps. However, many small islands surrounding Sulawesi have been neglected and have not been unexplored. Here, we report on the freshwater shrimps of the Banggai Archipelago, eastern Sulawesi, based on field collections between 2017 and 2019 on four islands, Peleng, Labobo, Bangkurung, and Banggai. Eleven species were found: Caridina brevidactyla J. Roux, 1920, Caridina brevicarpalis De Man, 1892, Caridina gracilipes De Man, 1892, Caridina gracilirostris De Man, 1892, Caridina serratirostris De Man, 1892, Caridina typus H. Milne Edwards, 1837, Caridina weberi De Man, 1892, Macrobrachium australe (Guérin-Méneville, 1838), Macrobrachium equidens (Dana, 1852), Macrobrachium lar (Fabricius, 1798), and Macrobrachium latidactylus (Thallwitz, 1891). One species, C. brevidactyla, is a newly recorded from Sulawesi. Knowledge of the diversity of the freshwater shrimp fauna can contribute to the conservation of species and their habitats. [ABSTRACT FROM AUTHOR]

Caribbean rivers are inhabited by native macrofauna with a diadromous life cycle. The factors influencing the upstream migration of diadromous species are not well understood. Suggested primary factors include species density, habitat suitability and food availability. We hypothesized that food quality could be a key parameter in the upstream migration of macrocrustaceans. We sampled the main shrimp species and their potential food sources along an altitudinal gradient in the Grand Carbet River of Guadeloupe. Lipid analyses of the different food items reveal that biofilm and drifting organic matter are main sources of eicosapentaenoic acid (EPA). Biofilm is richer in EPA upstream, while drifting material is richer in EPA downstream. These opposed altitudinal gradients are reflected in shrimp lipids depending on whether they feed on biofilm or drifting organic matter. In addition, low EPA levels in shrimp suggest that dietary EPA could be a limiting factor in this system and that this differential altitudinal distribution of EPA could influence shrimp settlement. [ABSTRACT FROM AUTHOR]

This study focused on 120 specimens of the shrimp Palaemon elegans collected in intertidal zones in eight selected areas. This study aimed to assess the suitability of P. elegans as a bioindicator of natural and anthropogenic marine pollution. Metal concentrations of aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) were measured in shrimp collected from various sites in the Canary Islands, including areas affected by volcanic activity, industrial activity, and control zones. The determination of metal concentrations was conducted using inductively coupled plasma optical emission spectrophotometry (ICP-OES). The results showed significant differences in metal concentrations across the studied sites, with the highest levels of Al, Cu, Fe, Pb, and Zn observed in areas impacted by the Tajogaite volcanic eruption and harbor activity. Sites near old landfills and sewage pipes also exhibited elevated levels of Cd, Cu, and Pb, indicating strong anthropogenic influence. Al was found in the highest concentration in Harbour, reaching 25.7 ± 6.2 mg/kg, while the lowest concentration was observed in Control Lp at 11.5 ± 0.69 mg/kg. Conversely, lower metal concentrations were detected in control zones and areas with high dinoflagellate presence, suggesting a potential role of bioremediation by marine phytoplankton. The ability of P. elegans to accumulate metals in its tissues, particularly in areas of high pollution, highlights its potential as a bioindicator species. This study underscores the importance of P. elegans in monitoring marine pollution and provides insights into the environmental impact of both natural and human-induced contamination on coastal ecosystems., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The aim of the study was to determine the toxic effect of ammonia concentration on juveniles of Palaemon adspersus, a shrimp species important for both fisheries and food webs. Juveniles of P. adspersus were exposed to various ammonia concentrations (NH3) in acute toxicity tests at four pH values (6-9). The 24, 48, 72 and 96-hour LC50 values of total ammonia nitrogen (TAN) ranged from 114.82 to 67.61 mg/dm³ at pH 6; from 120.23 to 69.18 mg/dm³ at pH 7; from 87.10 to 54.95 mg/dm³ at pH 8; from 79.43 to 19.95 mg/dm³ at pH 9. The 24, 48, 72 and 96-hour LC50 values of NH3-N varied within range of 0.054 to 0.037 mg/dm³ at pH 6, 0.569 to 0.309 mg/dm³ at pH 7, 3.846 to 2.291 mg/dm³ at pH 8 and 24.547 to 6.166 mg/dm³ at pH 9. It was determined that high pH values noticeably decreased the tolerance of juveniles of P adspersus to TAN and NH3-N. Mortality rates increased in parallel with increasing NH3 concentrations, pH and exposure time. [ABSTRACT FROM AUTHOR]

Primer registre de gambeta blanca Palaemon longirostris H. Milne Edwards, 1837 a les aigües mediterrànies del Marroc En aquest treball ressenyem el primer registre de gambeta blanca Palaemon longirostris, un crustaci palaemònid d’interès socioeconòmic, a les costes nord–orientals del Marroc. És el tercer registre de l’espècie confirmat al Mediterrani. Futurs estudis podrien ampliar la seva àrea de distribució coneguda al mar Mediterrani.

Passive acoustics monitoring (PAM) has been used to detect crustacean feeding activity. The aim of the present study was to evaluate the sound emission of the giant freshwater prawn Macrobrachium rosenbergii during feeding a commercial pelleted food in captivity, as well as described the sound generation mechanism and main acoustic variables for the first time. The structure responsible for sound emission was identified based on simultaneous audio and video recordings. Fourteen animals divided into three size classes were recorded individually. The acoustic parameters (sound duration, minimum, maximum and peak frequency and sound pressure level) of 80 sound pulses were analysed for each size classes. The giant freshwater prawn emits click sound when closing the mandibles to shred the food, as they collide with each other. Minimum and peak frequency were similar among the size classes, while the other acoustic parameters were significantly different, but they did not follow an apparent pattern in relation to the size of the prawns. The M. rosenbergii emits sound during feed consumption, and the acoustic parameters obtained in the present study could be useful to monitor feeding activity in prawn farming. [ABSTRACT FROM AUTHOR]

The impact of invasive alien species on native communities can act at different levels both by affecting the ecosystem’s structure (i.e., mainly in the case of vegetation) and through direct interactions (i.e., competition for food or space). Behavioral studies under controlled conditions can provide relevant information on both the invasive potential of alien species and the potential impact of the invaders on the local native species. In the laboratory, the competition for food resources between the invasive oriental shrimp Palaemon macrodactylus, Rathbun, 1902, and the Mediterranean native shrimp Palaemon elegans, Rathke, 1836, was analyzed. These species are typical residents of coastal transitional and estuarine waters, so the experiments were carried out using two salinity conditions that characterize the coastal lagoon of Venice. Although at both salinity treatments the alien species tended to be more aggressive than the native one, significant differences between the two species were mainly observed at a salinity of 30. In particular, at a salinity of 30, P. macrodactylus spent more time attending to the food source than the native species. The results are discussed in light of the potential inter-specific competition between the two species within the conditions of the Venice lagoon.

Two new species of the genus Macrobrachium Spence Bate have been described from near Mandalay of Ayeyarwady (Irrawaddy) River, Myanmar (22°2′37″N; 96°2′37″E). Macrobrachium univmandalay sp. nov. is closely related to Macrobrachium spinosum Cai & Ng, 2002 and Macrobrachium yui Holthuis, 1950 and is characterized by the presence of 10–12 dorsal teeth of which 3–4 post-orbital, first tooth at about 1/4th of anterior carapace; second chelate legs are dissimilar in size and shape in which carpus of major leg distinctly shorter than palm, cutting edges of fingers with 2 large and 2–3 smaller denticles at proximal part and without denticles on the distal half. Minor leg in which merus longer than carpus and palm, carpus shorter than palm as well as fingers and fingers without denticles in the cutting edges. M. spinosum and M. yui differ from this species in all these characters above. Macrobrachium ayeyarwadiense sp. nov. shows close affinity with Macrobrachium horstii de Man, 1892 and M. spinosum and can be easily separated on the basis of difference in characters of rostrum, position and arrangement of teeth on upper and lower margins, position of first dorsal tooth, distance between post-orbital edge and first dorsal tooth and its relation to rostrum length, length of antennular peduncle in relation to post-orbital carapace, shape and structure of 2nd cheliped, nature, size and arrangement of spines on outer and inner margins of ischium, merus, carpus, palm and fingers and nature of denticles on cutting edges of major and minor legs. The species can at once be identified on the absence of tubercles at distal half beyond larger denticles on fingers, convex nature of merus, carpus and disposition of spines on them, swollen palm and curved nature of movable finger and crossed nature of fingers distally of major 2nd peraeopod. Nature of long stiff setae on inner side of ischium, merus and carpus of major cheliped is characteristic to the species. Minor 2nd cheliped is also species specific in which the fingers are slender and curved so that a wide gap exists when closed. A note on Macrobrachium lamarrei (H. Milne Edwards 1937) is also given in the text. [ABSTRACT FROM AUTHOR]

In this study, we investigated which strategy Macrobrachium amazonicum populations use to survive in river and estuary environments. In each environment, abiotic factors were analyzed in situ, and ovigerous females and males of M. amazonicum specimens were captured. To determine ovarian maturity and morphotypes, gonads were removed and processed histologically, and the gonadosomatic index and condition factor (K) were determined. Ovigerous females were analyzed to determine the relationship between ovarian maturation and the embryonic phases of eggs in the brood pouch. Precipitation, turbidity and dissolved oxygen showed differences between the estuary and river. The population of ovigerous females showed that ovarian maturation was simultaneous with embryonic development. However, the freshwater prawn populations in the river were smaller and consisted of a greater number of ovigerous females with maturing and mature ovaries. In the estuary, ovigerous females with spawned and reorganized ovaries were observed more frequently. In males, the GC morphotype was absent in the river, where the TC morphotype predominated and showed similar reproductive conditions as the GC morphotype in the estuary. M. amazonicum has strategies for allocating energy for reproduction or growth in different environments. This description established the trade-off as a strategy used by M. amazonicum to maintain the population in adverse environments. [ABSTRACT FROM AUTHOR]

Multigene molecular revision of a series of specimens of the rare spongobiotic palaemonid shrimp genus, Onycocaridella Bruce, 1981, collected predominantly from Papua New Guinea, has doubled the known species diversity to six. Of the previously known species, O. monodoa (Fujino & Miyake, 1969) and O. stenolepis (Holthuis, 1952) were analysed in the present study, whereas sequenceable specimens of the type species, O. prima Bruce, 1981, were not available. The present molecular analysis (combined COI, 16S, H3 markers) recovered six separate genetic lineages, indicating the presence of four undescribed species. Three of the latter are described in the present study. Remarkably higher known species diversity of Onycocaridella is thus recorded from a single geographic region - Papua New Guinea. The increased diversity reported here was discovered by application of complementary collecting techniques (hand picking, stone brushing, dead-coral sorting, suction sampling). One of the present new species is also reported from Australia, and O. monodoa is newly recorded from New Caledonia. A revised diagnosis of the genus and a key to identification of all known species of Onycocaridella are provided. [ABSTRACT FROM AUTHOR]

A good understanding of a given species' embryology is important to settle the larval rearing bases when juveniles are required for culture purposes or conservation programs. Changes in embryonic morphology, protein concentration, and protein type occurring in prawn eggs were analyzed in the present work. Berried females of Macrobrachium tenellum were collected in the Colotepec River, Oaxaca, Mexico. The eggs were taken from the ovigerous mass and embryonic stages classified by their color. Morphological changes in the embryos allowed identifying six embryonic stages based on color, egg size, and morphological features. Determinations of the protein extract were executed in SDS-PAGE (electrophoresis in polyacrylamide gels) and, subsequently, proteomic analyses were also performed. Protein bands along embryonic development and their molecular weights are presented and commented. [ABSTRACT FROM AUTHOR]

&lt;b&gt;Background and Objective:&lt;/b&gt; The role of sediment in water bodies is significant because sediment can affect water quality and benthic organisms. This study investigated sediment's effect on the &lt;i&gt;Macrobrachium nipponense&lt;/i&gt; population in the Anzali Lagoon. &lt;b&gt;Materials and Methods:&lt;/b&gt; The samples were taken at three different sites of Anzali Lagoon in 2015. All the prawns cached by traps and sediment samples were taken exactly next to the traps. All samples were transported to the laboratory for analysis. Canonical correspondence analysis (CCA) was used to analyze the total catch for prawns across the sediment gradients measured. &lt;b&gt;Results:&lt;/b&gt; It showed clear separation in all sites. Site 2 is more affected by clay; in Site 2, the number and the weight of &lt;i&gt;M. nipponense&lt;/i&gt; were lower than in the other sites. In Sites 1 and 3, fine sand and medium sand were more affected, respectively. The results showed a relationship between the prawn population and sediment in the Anzali Lagoon. &lt;b&gt;Conclusion:&lt;/b&gt; In some parts of the Anzali Lagoon, the quality and quantity of sediments were different, which directly affected the population of &lt;i&gt;M. nipponense&lt;/i&gt;. Furthermore, because some parts of the lagoon are in good condition according to sediments and water quality, the Anzali Lagoon has a good potential for growing and living &lt;i&gt;M. nipponense&lt;/i&gt;.

Decapod crustaceans are a diverse group that exploits various types of habitats in Costa Rica, where they represent 8.1% of the marine diversity of the country. This group includes families containing species with strictly symbiotic behavior, e.g., the Palaemonidae and Pinnotheridae. Despite the high diversity of decapods and the importance of symbionts in marine ecosystems, very little research has been done regarding symbiosis in Costa Rica and the Central American region. The objective of the present study is to present a check list of the species of decapods that are associated with macroinvertebrates in Pacific Costa Rica. The research was carried out using different sources, including a literature review, the Crustaceans Collection of the Zoology Museum of the University of Costa Rica, and field surveys between 1970 and 2019 along the Pacific coast of Costa Rica, and Isla del Coco, 500 km offshore. One-hundred associations are reported, of 74 species of symbiotic decapods with six host phyla. Seventy-four associated with Cnidaria, 15 with Echinodermata, four each with Annelida and Mollusca, two with Chordata, and one with Porifera. In total, there were 14 new reports of decapods occurring on Isla del Coco and four new reports of decapods for Costa Rica: Pseudocoutierea elegans, Raytheres clavapedatus, Tuleariocaris holthuisi, and Calyptraeotheres pepeluisi. These results highlight the need to conduct more detailed studies to determine the real diversity and ecological importance of the associations between marine organisms. [ABSTRACT FROM AUTHOR]