Decapoda Research Articles

Shell disease syndromes of decapod crustaceans.

The term shell disease subsumes a number of debilitating conditions affecting the outer integument (the carapace) of decapod crustaceans, such as lobsters and crabs. Herein, we seek to find commonality in the aetiology and pathology of such conditions, and those cases that result in the progressive erosion of the cuticle through to the visceral tissues by a cocktail of microbial-derived enzymes including lipases, proteases and chitinases. Aquimarina spp. are involved in shell disease in many different crustaceans across a wide geographical area, but the overall view is that the condition is polymicrobial in nature leading to dysbiosis within the microbial consortium of the damaged cuticle. The role of environment, decapod behaviour and physiology in triggering this disease is also reviewed. Finally, we provide a conceptual model for disease aetiology and suggest several avenues for future research that could improve our understanding of how such factors trigger, or exacerbate, this condition.

A first glimpse into the m6A modification machinery of shrimp: Genomic features, expression patterns and potential roles in molting regulation

N6-methyladenosine (m6A) is the most abundant type of RNA modification in eukaryotes, yet information on the m6A methylation enzymatic machinery of decapod crustaceans is quite scarce. Here, three essential genes for m6A modification, including two m6A methyltransferases (LvMETTL3 and LvWTAP) and a m6A-binding protein (LvYTHDF2), were identified from the Pacific whiteleg shrimp Litopenaeus vannamei. Their genomic structures were dissected in an evolutionary context. Common transcription factor binding sites and conserved functional motifs were identified, but the three m6A modification genes also possessed some unique features, illustrating lineage-specific diversification of regulatory elements and functions of these genes. The three genes displayed ubiquitous tissue expression profiles, and showed dynamic expression changes at different molting stages. Following suppression of LvMETTL3, LvWTAP or LvYTHDF2 by RNA interference, the molting rate of shrimp was significantly accelerated, and expression of the molt inhibiting hormone MIH plummeted, while major genes in the ecdysone signaling pathway including EcR, RXR and E75 all showed significant induction. The results indicated that m6A modification may regulate shrimp molting process via MIH and the ecdysone signaling pathway. The current study provided the first molecular characterization of several key components of the m6A enzymatic machinery in penaeid shrimp, and established a foundation for further exploration of the roles of m6A modification in shrimp development and growth.

Effects of temperature experienced during embryonic development on biomass and C and N composition at hatching in Palaemon serratus (Pennant, 1777)

AbstractIn decapod crustaceans, the conditions experienced during embryonic development trigger phenotypic plasticity of the larvae at hatching. The objective of this study was to test the effects of temperature during embryonic development of Palaemon serratus on the phenotypic plasticity of hatching larvae. We incubated egg‐bearing females from eggs laying to hatching at four temperatures (10, 15, 18 and 20°C). Weight, carbon and nitrogen contents were measured on newly laid eggs and on freshly hatched larvae. The duration of embryonic development was negatively correlated with incubation temperature. At 20°C, all females abandoned their eggs during development. Incubation temperature had no effect on the weight and the percentage of N of the larvae at hatching, while it did affect their percentage of C and their C/N ratio. Embryos incubated at 10°C seemed to produce larvae with fewer lipid reserves than those incubated at 15 and 18°C. They probably overconsumed their lipid reserves to compensate for the metabolic losses due to the low temperature. These results provide information on the link between maternal investment per egg and larval development in P. serratus.

Established and Emerging Research Trends in Norway Lobster, Nephrops norvegicus.

The burrowing crustacean decapod Nephrops norvegicus is a significant species in European Atlantic and Mediterranean fisheries. Research over the decades has mainly focused on behavioral and physiological aspects related to the burrowing lifestyle, since animals can only be captured by trawls when engaged in emergence on the seabed. Here, we performed a global bibliographic survey of all the scientific literature retrieved in SCOPUS since 1965, and terminology maps were produced with the VOSviewer software to reveal established and emerging research areas. We produced three term-map plots: term clustering, term citation, and term year. The term clustering network showed three clusters: fishery performance, assessment, and management; biological cycles in growth, reproduction, and behavior; and finally, physiology and ecotoxicology, including food products. The term citation map showed that intense research is developed on ecotoxicology and fishery management. Finally, the term year map showed that the species was first studied in its morphological and physiological aspects and more recently in relation to fishery and as a food resource. Taken together, the results indicate scarce knowledge on how burrowing behavior and its environmental control can alter stock assessment, because of the poor use of current and advanced monitoring technologies.

Testosterone and steroidogenic genes in the male blue crab Callinectes sapidus and their relationship with insulin-like androgenic gland factor (IAG) and crustacean female sex hormone (CFSH)

The abundance of the blue crab, Callinectes sapidus, has been declining in the Chesapeake Bay, possibly due to reduced spawning stock and deteriorating habitat conditions. Callinectes female reproductive capacity, i.e., fertilization efficiency, may depend on the quality and number of sperm stored in the spermathecae. Understanding endocrine regulation in male development and reproduction is necessary. Sexual differentiation of decapod crustaceans is primarily regulated by the insulin-like androgenic gland factor (IAG) and crustacean female sex hormone (CFSH). This system contrasts with the vertebrates wherein testosterone (T) controls male reproduction, sexual differentiation, and sex-specific behavior and physiology. With earlier reports of T presence in some decapods, this work aimed to determine if the blue crab Callinectes sapidus males exhibit T and if the corresponding levels are related to IAG and CFSH transcripts. To this end, the IAG and CFSH transcripts are estimated in the androgenic glands (AG) and eyestalk ganglia of juvenile and adult males, respectively. The levels of IAG transcripts are significantly (p < 0.05) higher in adult AGs than in juveniles. However, this pattern contrasts with CFSH transcripts in the eyestalk ganglia with juveniles higher than adults. The levels of T in adult testis, posterior vas deferens, AG, and hemolymph are significantly (p < 0.05) higher than those in juveniles. The presence of authentic T is further confirmed by liquid chromatography with tandem mass spectrometry. The transcript levels of the following genes known to be involved in vertebrate steroidogenesis are determined: StAR-related lipid transfer protein 3 (StAR3); 3β-hydroxysteroid dehydrogenase (3βHSD); two isoforms of 17β-hydroxysteroid dehydrogenase 8 (17βHSD8); and, 5α-reductase (5α-red). StAR3 levels are significantly (p < 0.05) higher in adult testis, anterior vas deferens, and AG than in juveniles. In comparison, 5α-red levels in testis, anterior vas deferens, posterior vas deferens, and AG of adults are significantly (p < 0.05) lower than in juveniles. The 5α-red transcripts are localized in the spermatocytes and spermatids in the testis and AG cells in the AG using in situ hybridization. These results indicate that CFSH may suppress IAG expression; the levels of T may be related to the male reproductive activity; and a putative regulatory interaction among IAG, CFSH, and steroidogenic genes in T synthesis may present in decapod crustaceans.

DNA barcoding, dwelling morphology, and fecundity of the gall-forming shrimp Paratypton siebenrocki Balss, 1914 (Caridea: Palaemonidae)

ABSTRACT Tropical coral reefs offer a wide variety of habitats to countless invertebrate species. Sessile host organisms especially are inhabited by small taxa, of which decapod crustaceans form one of the most diverse communities. Symbiotic palaemonid shrimp species associate with marine invertebrate hosts from multiple phyla, including cnidarians such as stony corals (Scleractinia). The intriguing gall-forming shrimp Paratypton siebenrocki, a symbiont of Acropora corals in the Indo-Pacific, was collected in the Saudi Arabian Red Sea, Kenya, and the Maldives. Based on morphology P. siebenrocki has been considered to be most closely related to the genera Anapontonia and Metapontonia; however, no clear clustering with either palaemonid genus was observed in a phylogenetic reconstruction based on 16S and COI mtDNA. Here we photo-document the dwellings of P. siebenrocki in Acropora spp. for the first time, and furthermore we report on the reproductive output of this species. The number of eggs ranged from 345 to 909 (n = 6), and embryo volume differed strongly between early- and late-stage embryos. The carapace length ranged from 2.58 to 4.55 mm for the females and 1.51 to 2.5 mm for the males (n = 5). The number and size of the embryos, combined with their specialised, secluded lifestyle, suggest that P. siebenrocki allocates higher energy towards embryo production than free-living confamilials do.

Effects of Water Quality on the Growth, Molting and Mortality Of Mud Crab, Scylla Serrata Forskal (Decapoda: Portunidae) From Cox’s Bazar

The important decapod crustacean, the soft-shell crab, Scylla serrata is in great demand in different countries due to its taste next to shrimp and nutritional value, for which its farm is growing day by day as a source of income generation. This experiment was conducted for one year from January 2016 to December 2016 in Chaufaldandi, Cox’s Bazar, Bangladesh to study the growth, molting and mortality rates of the soft shell crab and water quality of the crab culture pond. During the three experiments in a year, matured male crab showed highest growth performance (28.00±7.02g to 32.15±3.87g). Mature female crab showed maximum molting (60%) during the 3rd experimental period (September to December), while immature crab depicted the highest rate of molting (75%) in the 2nd (May-August) and 3rd experimental periods (September- December). Mortality rate was found highest in mature male during the 1st experimental period (60%). The female crab showed maximum mortality rate (40%) during the 1st experimental period. The survival rate was best for female and immature S. serrata. The growth of S. serrata showed significant positive relationships with water temperature, salinity, water pH, soil pH, and alkalinity during the all three experimental periods. The 2nd and 3rd experimental periods were found to be the most favorable time to produce soft-shell crab due to suitable weather conditions. J. Biodivers. Conserv. Bioresour. Manag. 2022, 8(2): 25-36

ПЕРША ЗНАХІДКА РОДУ ARCTICOCARCINUS SHWEITZER ET AL., 2016 (DECAPODA, BRACHYURA) У ДАНСЬКОМУ ЯРУСІ КРИМУ (УКРАЇНА) ТА ЇЇ ПАЛЕОБІОГЕОГРАФІЧНЕ ЗНАЧЕННЯ

The Paleogene decapod crustaceans of Ukraine are insufficiently studied. This group of arthropods has not attracted much attention of researchers, despite the fact that the remains of decapods are known in the Paleogene sediments of the Dnipro River area, Donetsk Basin, the Crimea and the Ukrainian Carpathians. The article describes the first find of a decapod crustacean of the genus Arcticocarcinus Schweitzer et al, 2016 in Ukraine. The fossil comes from the lower part of the Danian of the Crimea (Ak-kaya Section near the Bila Skelia, Bilogirsk District). The fossil was found in situ in the decapod burrow Thalassinoides Ehrenberg, 1944. Such finds allow us to establish which fossil decapod crustaceans produced burrows Ophiomorpha, Thalassinoides, and Spongeliomorpha. Sediments with crab remains were accumulated in the environment of Skolithos Ichnofacies. This ichnofacies is usually confined to areas of the seabed whose sediments are constantly mixed by waves. There was a cold-water paleobasin on the territory of modern northern Ukraine in the Danian Age. This basin was connected to the Western European paleobasin and the Boreal paleobasin. The southern basin, located in the Carpathians, the Black Sea Depression, and the Crimea, was much warmer and closely connected with the Mediterranean Basin. A representative of the genus Arcticocarcinus was first found outside Sweden. It is very unlikely that the genus Arcticocarcinus Schweitzer et al, 2016 entered modern Sweden from the Crimea or vice versa via the Polish Channel, as the Carpathian flysch basin was obviously a barrier. Apparently, the exchange of fauna took place through the Dnipro-Donetsk Sea and the Pripyat Strait. These basins were part of the so-called "Sea of Arkhangelskyi" (a large sublatitudinal basin that stretched from the spurs of the Caucasus and the Urals to Western Europe). Arcticocarcinus cf. insignis (Segerberg, 1900) expands the paleontological characteristics of the Danian of Crimea and testifies to the free exchange of benthic faunas of North-Western Europe and Crimea.

The efficacy of electrical stunning of New Zealand rock lobster (Jasus edwardsii) and freshwater crayfish (Paranephrops zealandicus) using the Crustastun™.

Large numbers of decapod crustacea are farmed and harvested globally for human consumption. Growing evidence for the capacity of these animals to feel pain, and therefore to suffer, has led to increased concern for their welfare, including at slaughter. In New Zealand, decapod crustacea are protected by animal welfare legislation. There is a requirement that all farmed or commercially caught animals of these species killed for commercial purposes are first rendered insensible. The aim of this study was to evaluate the efficacy of the Crustastun™, a commercially available bench-top electrical stunner, in two commercially important New Zealand crustacean species; the rock lobster (Jasus edwardsii) and kōura (freshwater crayfish [Paranephrops zealandicus]). Animals were anaesthetised via intramuscular injection of lidocaine and instrumented to record the electrical activity of the nervous system, prior to being stunned according to the manufacturer's instructions. Stunning efficacy was determined by analysing neural activity and observing behaviour post stunning. All ten P. zealandicus and three J. edwardsii appeared to be killed outright by the stun. Of the remaining J. edwardsii, six exhibited some degree of muscle tone and/or slow unco-ordinated movements of the limbs or mouthparts after stunning, although there was no recovery of spontaneous or evoked movements. One J. edwardsii was unable to be stunned successfully, likely due to its very large size (1.76kg). None of the successfully stunned animals showed any evidence of return of awareness in the five minutes following stunning. It was concluded that the Crustastun™ is an acceptable method for killing P. zealandicus and for stunning all but the largest J. edwardsii.

Six new records of decapod crustacean species (Anomura, Brachyura) from southern Brazil

Six new records of decapod crustacean species (Anomura, Brachyura) from southern Brazil

Internal anatomy of a brachyuran crab from a Late Cretaceous methane seep and an overview of internal soft tissues in fossil decapod crustaceans

Internal anatomy of a brachyuran crab from a Late Cretaceous methane seep and an overview of internal soft tissues in fossil decapod crustaceans

Report from the 8th Symposium on Fossil Decapod Crustaceans, Zaragoza (Spain), June 2022

Report from the 8th Symposium on Fossil Decapod Crustaceans, Zaragoza (Spain), June 2022

Miocene decapod crustacean faunas from Cyprus – Part 1. Geographical-stratigraphical setting and Anomura

Miocene decapod crustacean faunas from Cyprus – Part 1. Geographical-stratigraphical setting and Anomura

Rogueus belgodereae, a new raninoid crab (Crustacea: Brachyura: Raninoidea) from the Upper Palaeocene (Thanetian) of Southern France, with comments on early palaeocene decapod crustacean faunules

Rogueus belgodereae, a new raninoid crab (Crustacea: Brachyura: Raninoidea) from the Upper Palaeocene (Thanetian) of Southern France, with comments on early palaeocene decapod crustacean faunules

Habitat and trophic niche overlap among juvenile black sea bass, tautog, and cunner: interspecific interactions amid a species geographic range expansion

Juvenile black sea bass Centropristis striata populations are increasing in southern New England estuaries of the northeastern USA with possible trophodynamic effects on labrid species: tautog Tautoga onitis and cunner Tautogolabrus adspersus. In this study, we examined the abundance, size-structure, and feeding ecology of juvenile sea bass and labrids in Narragansett Bay (Rhode Island, USA) from June to October in 2018 and 2019 and evaluated potential interspecific competition using habitat, diet, and isotopic niche overlap indices. Juveniles (age-0+) of each fish species spatiotemporally co-occurred in shallow, polyhaline habitats throughout the estuary. Age-0 cohorts were numerically dominant across species and initially recruited to the study area in July (minimum total length, TL = 15-20 mm), reached peak abundances in mid- to late summer (maximum abundances = 12-140 fish 100 m-2), and emigrated from field sites in October (maximum TL = 85-96 mm). Stomach content and stable isotope (δ15N and δ13C) analyses determined that focal fishes were generalist carnivores that foraged in bentho-pelagic food webs. Fishes also overlapped in their respective ambit and core isotopic niche space, but interspecific dietary overlap was size-dependent. Dietary overlap was most pronounced between sea bass ≤49 mm TL and labrids ≤59 mm TL due to their mutual reliance on gammarid and caprellid amphipods. Ontogenetic dietary shifts then resulted in food niche segregation, such that sea bass 50-139 mm TL consumed decapod crustaceans and fish, whereas labrids 60-181 mm TL mainly fed on amphipods, worms, bivalves, and turf-associated biota, i.e. bryozoans, hydroids, and seaweeds. Habitat and trophic niche overlap between early juvenile sea bass and labrids purportedly have not caused opposite population trajectories or food resource limitation in Narragansett Bay, indicating an absence of exploitative competition. Alternatively, realized competition between species may be too spatiotemporally restricted to alter their population dynamics. Continuous monitoring of the sea bass’s bio-ecological effects in southern New England estuaries is warranted, however, given their recent range expansion and increasing abundances at northern latitudes.

Palaeoebiological implications of cuticle morphology, microstructure and formation in modern and fossil Daira (Decapoda, Brachyura, Dairoidea)

The origin and function of peculiar mushroom-shaped cuticular structures in some decapod crustaceans remains unknown. This ornamentation has appeared several times in widely disparate clades (in podotreme and heterotreme crabs, and pagurids). These structures are analysed in the modern genus Daira and compared with fossil material from the Eocene of Huesca and the Miocene of Alicante and Mallorca. A morphological and petrographic study is carried out using conventional microscopy and Scanning Electron Microscopy to understand the microstructure in modern and fossil representatives. This provides a clear view of the mushroom-like structures that cover the carapace of Daira and the distribution of the different layers of the exoskeleton. The results reveal a complex morphology, which involves all layers of the cuticle, with changes in the thickness of the exocuticle in different areas, and the presence of conical structures that especially affect the outer layers. These convolutions form a network of channels connected to the outside by pores. Finally, possible anti-predatory functions of these complex structures are proposed.

Resistance to white spot syndrome virus in the European shore crab is associated with suppressed virion trafficking and heightened immune responses.

All decapod crustaceans are considered potentially susceptible to White Spot Syndrome Virus (WSSV) infection, but the degree of White Spot Disease (WSD) susceptibility varies widely between species. The European shore crab Carcinus maenas can be infected with the virus for long periods of time without signs of disease. Given the high mortality rate of susceptible species, the differential susceptibility of these resistant hosts offers an opportunity to investigate mechanisms of disease resistance. Here, the temporal transcriptional responses (mRNA and miRNA) of C. maenas following WSSV injection were analysed and compared to a previously published dataset for the highly WSSV susceptible Penaeus vannamei to identify key genes, processes and pathways contributing to increased WSD resistance. We show that, in contrast to P. vannamei, the transcriptional response during the first 2 days following WSSV injection in C. maenas is limited. During the later time points (7 days onwards), two groups of crabs were identified, a recalcitrant group where no replication of the virus occurred, and a group where significant viral replication occurred, with the transcriptional profiles of the latter group resembling those of WSSV-susceptible species. We identify key differences in the molecular responses of these groups to WSSV injection. We propose that increased WSD resistance in C. maenas may result from impaired WSSV endocytosis due to the inhibition of internal vesicle budding by dynamin-1, and a delay in movement to the nucleus caused by the downregulation of cytoskeletal transcripts required for WSSV cytoskeleton docking, during early stages of the infection. This response allows resistant hosts greater time to fine-tune immune responses associated with miRNA expression, apoptosis and the melanisation cascade to defend against, and clear, invading WSSV. These findings suggest that the initial stages of infection are key to resistance to WSSV in the crab and highlight possible pathways that could be targeted in farmed crustacean to enhance resistance to WSD.

A Review of the Emerging Risks of Acute Ammonia Nitrogen Toxicity to Aquatic Decapod Crustaceans

Waterborne ammonia is becoming one of the most notorious pollutants in aquatic habitats and has been shown to induce a range of ecotoxicological effects on aquatic animals. High ammonia concentrations occur mainly in intensive aquaculture systems, and effective wastewater treatment and agricultural systems are necessary to treat excessive nitrogenous compounds. Ammonia can enter aquatic decapod crustaceans through their gills, thereby reducing the oxygen-carrying capacity of blood cells and damaging the structures of organs such as the gills and hepatopancreas. This ultimately results in oxidative stress, immunotoxicity, and high mortality. Crustaceans have the ability to exert detoxification functions against ammonia stress by regulating the permeation of ammonia and related nitrogenous compounds through membranes. To the best of our knowledge, a comprehensive review of the acute toxicity of ammonia to crustaceans is lacking. The present review focuses on the literature on the problems and mechanisms concerning ammonia-induced acute toxicity and aims to synthesize the knowledge of the relationship between ammonia stress and defense responses in crustaceans (mainly shrimp and crabs). This review also emphasizes the uptake, elimination, and detoxification of ammonia in crustaceans.

Invertebrate larvae in the Chira river estuary, Vichayal, Peru.

The species of invertebrate larvae present in the Chira River estuary, Vichayal district, Paita - Piura, were determined. The capture was carried out using two artisanal larval techniques (Avión and Chayo). 3 sampling stations were established (right bank, left bank and main entrance of the estuary). 33 samples were obtained from September 2017 to July 2018, 23 invertebrate larvae are reported, representing 22 species, 16 families, 5 orders and 3 classes and an undetermined species belonging to the Ophiura class. In-situ physicochemical parameters were evaluated, the ambient temperature presented a maximum of 26 °C in February and a minimum of 18.2 °C in October, the surface temperature of the water presented a maximum of 26.1 °C in February and a minimum of 18.5 °C in October and the salinity varied between 18 UPS (station 1) and 5 UPS (station 3). Decapod crustaceans had the highest presence of invertebrate larvae from the Chira River estuary with 78.25%. Temperature and salinity are determining factors for the presence of the larval stages of these organisms in the estuary.

Forest conversion adversely affects native Macrobrachium shrimp assemblages in tropical Malaysian streams

Abstract Commodity‐driven forest conversion represents one of the most severe threats to freshwater biodiversity in Southeast Asia, notably causing population declines and the extinction of freshwater fish species. Although a variety of freshwater taxa are likely to be adversely affected by forest conversion, little is known about the impact on ecologically and economically important invertebrates such as decapod crustaceans. This study evaluated the impact of forest conversion and land‐use change on freshwater Macrobrachium shrimp species, using species richness, abundance, and environmental data collected from 20 streams across southern Peninsular Malaysia. Streams were located in three types of landscape: forest; oil palm plantation; and mixed land use, comprising young secondary forest, small‐scale plantations, patches of open and sparsely vegetated areas, and agricultural fields and clearings. Generalized linear models showed that even incomplete change from forest habitats to mixed land use and oil palm plantation resulted in significantly lower Macrobrachium native species richness and higher non‐native species abundance. Native species richness was positively correlated with canopy cover, leaf litter, substrate size, and dissolved oxygen, and was negatively correlated with water temperature and conductivity. Native species richness was also negatively correlated with non‐native species abundance, with non‐native species abundance increasing along the human disturbance gradient. These results highlight the need for riparian habitat protection to conserve native Macrobrachium and limit the spread of non‐native species. A management priority should be to maintain or restore optimum instream habitat conditions for shrimps, which would also benefit fish and other benthic macroinvertebrates. Suitable riparian management requires substantial support and funding from multiple stakeholders, but it can be aligned with other catchment‐based strategies to optimize the use of limited resources available for freshwater biodiversity conservation.