Abstract Crustacean aquaculture, especially monosex culture, requires a comprehensive knowledge of the mechanisms regulating sex determination and differentiation. Decapod crustaceans display either ...female heterogamety (ZW/ZZ) or male heterogamety (XY/XX) as their mode of genotypic sex determination. However, some decapod species exhibit sexual plasticity via removing the androgenic gland, knockdown insulin receptor transcripts, administrating exogenous sex steroids, and altering environmental factors. Although the master sex‐determining gene in decapods remains elusive, various sexual genes, hormones, and neurotransmitter are emerging as important factors in sex differentiation. This review looks into recent advancements in studies related to the genetic sex determination system and factors that trigger sex reversal. Moreover, the elucidation of the role of genetic factors in sex differentiation in both females and males, as well as their underlying interrelated regulatory mechanisms, provides justification for three levels of application: the induction of monosex populations, detection of precocious sex and genotype, and prevention of uncontrolled reproduction. Finally, we proposed future directions of bioinformatics analysis and genome editing coupled with sex control to increase the yield for economic decapods. In conclusion, this review provides a foundation for future research on the reproductive biology and sexual regulation of decapods, with the aim of aiding practitioners in advancing the crustacean aquaculture industry.
The timing of metamorphosis has recently been referred as a more suitable proxy to evaluate postlarval quality than size. Indeed, while displaying a larger size at settlement, late settlers that ...originate from larvae that have delayed metamorphosis commonly display poorer growth performances This delay in metamorphosis is possibly at the expenses of larval endogenous energetic reserves that, once allocated to facilitate the delayed transition to benthic life, will no longer be available to help fuelling early juvenile somatic growth. To further advance our knowledge on this topic, we evaluated the physiological status (energy reserves and allocation, aerobic and anaerobic energy consumption), along with biochemical responses related with detoxification processes, antioxidant defences, oxidative damage, neuromotor activity in early settlers (ES), middle settlers (MS) and late settlers (LS) of postlarvae of the marine ornamental shrimp Lysmata seticaudata. Our results revealed that LS postlarvae presented a higher weight compared to MS and ES, likely related with a lower metabolism and neuromotor activity. Yet, the low metabolism allied with diminished detoxification and antioxidant capacities seemed to result in an increased oxidative stress condition that may negatively condition the growth performance of LS postlarvae. Conversely, ES postlarvae presented a lower weight, likely because of high metabolic costs associated with increased neuromotor activity, detoxification, and antioxidant capacities to avoid oxidative damage. The present study highlights how the physiological, metabolic and biochemical status of L. seticaudata postlarvae is shaped by the timing of their metamorphosis, as well as how this event will shape their early benthic life and confirms that a larger size or weight at metamorphosis may not be good proxies to select premium seedlings for grow-out. Overall, metamorphosis is not a new beginning and does not reset larval history. Crustacean farmers should avoid decoupling larviculture history from grow-out, as only by knowing larval performance to metamorphosis will it be possible to enhance survival and growth performances to commercial size.
•Postlarvae that delayed metamorphosis (late settlers) display a higher weight.•Late settlers have a lower metabolism and neuromotor activity.•Delaying metamorphosis results in an increased oxidative stress condition.•Early settlers show higher neuromotor activity and antioxidant capacity.•Physiological status is a better proxy for postlarval quality than weight.
The presence of an Oxygen Minimum Zone (OMZ) is one of the major characteristics of the eastern Pacific. The OMZ changes strongly adjacent to Mexico in its thickness and intensity. The ecological ...impacts of those changes were studied by examining the community structures of bathyal benthic and bentho-pelagic decapod crustaceans, and their oceanographic contexts, on the Mexican Pacific slope along a wide latitudinal range (16–32°N). Decapod crustaceans were collected with a benthic sledge from 48 stations between 865 and 2165m in three main areas: offshore of northern Baja California (NBC), off southern Baja California (SBC) and in the southern Mexican Pacific (SMP). Physical–chemical parameters were measured in the water column, and sediment composition was analyzed for each station. The narrowing and weakening of the OMZ north of ca. 26°N was confirmed. Water with dissolved oxygen <0.5mll−1 occupied a stratum of 1231m in the SMP vs. only 664m off NBC. The strongest changes coincided with a region of surface, subsurface and intermediate water mass transitions, where less saline waters from the north extended to depths of ca. 1000m. Sand proportions were higher in sediments to the south, whereas silt dominated offshore of NBC. A strong latitudinal shift in decapod community composition and bathymetric distribution occurred from off SBC to off NBC, coinciding with changes in oceanographic conditions. The dominant genera of decapod crustaceans at slope depths were cognate to those dominating slope areas in other tropical and subtropical regions of the world. In the SMP and off SBC, large aggregations of organisms were observed at 900–1300m, with a sharp decrease in abundance at greater depth. Off NBC, the density of organisms was intermediate at all depths. The combined effects of dissolved oxygen concentration and characteristics of water masses affected the distribution of organisms. The faunal patterns were also related with sediment grain size.
Osmoregulation is an essential physiological process for the majority of aquatic crustaceans since it enables them to cope with the changes/discrepancies between the ion concentrations within their ...bodies and the aquatic environments they inhabit. With the exception of strict osmoconformers, crustaceans living in all aquatic environments continually regulate their hemolymph osmolytes and ultimately, the strategy and strength of this process dictate the diversity of habitats a crustacean can successfully occupy. While the degree of the osmoregulatory response is largely salinity dependent, the actual strength is highly species-specific. This has obvious and significant implications to the crustacean aquaculture industry, a multi-billion dollar industry that is continuously growing worldwide. Unfortunately, to date, a comprehensive review discussing the implications of this crucial process in crustaceans from an aquaculture perspective is lacking. Since crustacean aquaculture is almost exclusively based on large decapods, which also forms the main body of literature, they will therefore be the main focus of review. With basic background information on the regulatory mechanisms briefly described as a foundation for necessary knowledge, the implications of increased osmoregulatory demands to crustacean aquaculture is discussed extensively based on recent literature and research conducted in our laboratory. This includes the various factors that may influence osmoregulatory abilities, the causes leading to reduced productivity at sub-optimal salinities, potential methods that may broaden tolerable salinity ranges and how osmoregulation may interact with another important physiological process, i.e. ammonia excretion, which is crucial for cultured crustaceans. At the end of the review, future research directions are suggested to advance our understanding regarding this complex process that could substantially affect crustacean aquaculture productivity.
The high accumulation potential of estuaries for plastics, particularly microplastics, poses a threat to the high societal value and biodiversity they provide. To support a spatially refined ...evaluation of the risk that microplastic pollution poses to fauna utilizing estuarine sedimentary habitats, we investigated the distribution of microplastics (lower limit of quantification, LOQ = 62 μm) at the sediment surface of two dominant habitats, and subsequently compared microplastic burdens between two crabs species utilizing these habitats. Microplastics were dominated by low density polyolefins (45–50 %), comparable to the polymer composition of macroplastics. The vast majority (99 %) of microplastics were ≤1 mm, and increased exponentially (with an exponent of 2.7) in abundance at smaller sizes, hinting at three-dimensional fragmentation. Our results suggest that the presence of vegetation needs to be accounted for in risk assessments with small microplastics (≥62 μm and ≤1 mm) on average 2.6 times more prevalent within reed beds compared to mudflats. Additionally, sediment properties also play a role with an exponential decrease in small microplastic abundance at coarser sediments, increased organic matter content, and decreased water content. These results suggest that at specific locations, such as the study area, local sources can provide a substantial contribution to microplastic contamination. To translate these habitat- and site-specific differences into a risk assessment relevant for macroinvertebrates, ecological traits such as differences in feeding modes should be accounted for, as we found substantial differences in both size and abundance of microplastics in gastrointestinal tracts of two crab species, Chiromantes dehaani and Chasmagnathus convexus, with different feeding modes.
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•We aimed to support a spatially refined risk evaluation of microplastics in estuaries.•Microplastics were about 2.6 times more prevalent within reed beds than mudflats.•Microplastic abundance decreased exponentially with larger sediment grain size.•A power-law decrease in microplastic size hinted at three-dimensional fragmentation.•Microplastic size and abundance differed between crabs with different feeding modes.
The crab species Plagiolophus sulcatus Beurlen, 1939 from the Oligocene (Rupelian) Kiscell Clay of Hungary is revised and its holotype is reillustrated for the first time since its original ...publication. Material from the upper Oligocene (Chattian) of Trbovlje (Slovenia) is here considered conspecific with P. sulcatus. Attribution of this species to the genus Glyphithyreus, as proposed by Hiroaki Karasawa and Carrie Schweitzer in 2004, is confirmed. Glypthithyreus sulcatus differs from congeners in possessing protogastric regions that are subtriangular in outline and in having fewer and coarser tubercles on elevated carapace regions.
G-protein coupled receptors (GPCRs) are ancient, ubiquitous, constitute the largest family of transducing cell surface proteins, and are integral to cell communication via an array of ...ligands/neuropeptides. Molt inhibiting hormone (MIH) is a key neuropeptide that controls growth and reproduction in crustaceans by regulating the molt cycle. It inhibits ecdysone biosynthesis by a pair of endocrine glands (Y-organs; YOs) through binding a yet uncharacterized GPCR, which triggers a signalling cascade, leading to inhibition of the ecdysis sequence. When MIH release stops, ecdysone is synthesized and released to the hemolymph. A peak in ecdysone titer is followed by a molting event. A transcriptome of the blackback land crab Gecarcinus lateralis YOs across molt was utilized in this study to curate the list of GPCRs and their expression in order to better assess which GPCRs are involved in the molt process.
Ninety-nine G. lateralis putative GPCRs were obtained by screening the YO transcriptome against the Pfam database. Phylogenetic analysis classified 49 as class A (Rhodopsin-like receptor), 35 as class B (Secretin receptor), and 9 as class C (metabotropic glutamate). Further phylogenetic analysis of class A GPCRs identified neuropeptide GPCRs, including those for Allatostatin A, Allatostatin B, Bursicon, CCHamide, FMRFamide, Proctolin, Corazonin, Relaxin, and the biogenic amine Serotonin. Three GPCRs clustered with recently identified putative CHH receptors (CHHRs), and differential expression over the molt cycle suggests that they are associated with ecdysteroidogenesis regulation. Two putative Corazonin receptors showed much higher expression in the YOs compared with all other GPCRs, suggesting an important role in molt regulation.
Molting requires an orchestrated regulation of YO ecdysteroid synthesis by multiple neuropeptides. In this study, we curated a comprehensive list of GPCRs expressed in the YO and followed their expression across the molt cycle. Three putative CHH receptors were identified and could include an MIH receptor whose activation negatively regulates molting. Orthologs of receptors that were found to be involved in molt regulation in insects were also identified, including LGR3 and Corazonin receptor, the latter of which was expressed at much higher level than all other receptors, suggesting a key role in YO regulation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hydrothermal vent ecosystems are home to a wide array of symbioses between animals and chemosynthetic microbes, among which shrimps in the genus Rimicaris is one of the most iconic. So far, studies ...of
symbioses have been restricted to Atlantic species, including Rimicaris exoculata, which is totally reliant on the symbionts for nutrition, and the mixotrophic species Rimicaris chacei. Here, we expand this by investigating and characterizing the symbiosis of the Indian Ocean species Rimicaris kairei using specimens from two vent fields, Kairei and Edmond. We also aimed to evaluate the differences in mineralogy and microbial communities between two cephalothorax color morphs, black and brown, through a combination of 16S metabarcoding, scanning electron microscopy, fluorescent
hybridization, energy-dispersive X-ray spectroscopy, and synchrotron near-edge X-ray absorption structure analyses. Overall, our results highlight that R. kairei exhibits similar symbiont lineages to those of its Atlantic congeners, although with a few differences, such as the lack of Zetaproteobacteria. We found distinct mineralization processes behind the two color morphs that were linked to differences in the vent fluid composition, but the symbiotic community composition was surprisingly similar. In R. exoculata, such mineralogical differences have been shown to stem from disparity in the microbial communities, but our results indicate that in
this is instead due to the shift of dominant metabolisms by the same symbiotic partners. We suggest that a combination of local environmental factors and biogeographic barriers likely contribute to the differences between Atlantic and Indian Ocean
symbioses.
Hydrothermal vent shrimps in the genus
are among the most charismatic deep-sea animals of Atlantic and Indian Oceans, often occurring on towering black smokers in dense aggregates of thousands of individuals. Although this dominance is only possible because of symbiosis, no study on the symbiosis of Indian Ocean
species has been conducted. Here, we characterize the
symbiosis by combining molecular, microscopic, and elemental analyses, making comparisons with those of the Atlantic species possible for the first time. Although most symbiotic partners remained consistent across the two oceans, some differences were recognized in symbiont lineages, as well as in the mechanisms behind the formation of two color morphs with distinct mineralogies. Our results shed new light on relationships among mineralogy, environmental factors, and microbial communities that are useful for understanding other deep-sea symbioses in the future.
Spiny lobsters (P. penicillatus, P. longipes and P. versicolor) are heavily dependent on habitats like coral reefs, known to be highly vulnerable to climate change-driven degradation. Yet, little is ...known about their trophic ecology and their adaptive capacity to a changing environment. In this study, we used fatty acids (FA) analysed in the hepatopancreas and δ13C and δ15N stable isotopes analysed in the tail muscle of three spiny lobster species from the Seychelles coastal waters to (1) infer habitat use, dietary patterns and potential for resource competition and (2) investigate the effects of reef type and coral bleaching on their trophic niche metrics. We found that there was a potential for interspecific competition between the three species, shown by their high dietary overlap (mean FA niche overlap ranging from 71.2% to 99.5% for P. longipes and P. versicolor in P. penicillatus) and similar habitat use (δ13C value ranges). P. penicillatus, the largest of the three species, was more a generalist than the two other species (i.e., had a larger FA niche) and P. versicolor seemed to feed on smaller/earlier life stage prey than P. longipes (based on differences in δ15N values). The potential for resource competition of Seychelles spiny lobsters appeared higher in granite than carbonate reefs, and in post-2016 coral bleaching reefs. Our results suggest that P. penicillatus could have a greater adaptive capacity to climate change due to its higher dietary plasticity and that competition between Seychelles spiny lobsters may increase in the future as the frequency and severity of bleaching events is predicted to increase with climate change.
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•We use trophic niche overlap to identify the potential for resource competition.•There is a potential for resource competition between three spiny lobsters species.•The largest species had the most diverse diet and the highest δ15N values.•Potential for competition was higher in the less vulnerable reef habitat type.•Potential for competition seemed to increase following a coral bleaching event.
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