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Background The Juan Fernández rock lobster Jasus frontalis (H. Milne-Edwards, 1837) is found along the Juan Fernández archipelago and Desventuradas Islands in the southeastern Pacific Ocean where it supports a profitable but likely unsustainable artisanal fishery. Only a few genomic resources are available for this species to support efficient managing practices. In this study, we took a first look at the genome of J. frontalis profiting from recently developed bioinformatics tools that mine for biological insight from low sequencing-depth datasets. Specifically, we have (i) estimated the nuclear genome size, (ii) assembled and described in detail the mitochondrial genome, (iii) discovered, quantified, and annotated nuclear transposable elements, and (iv) examined the phylogenetic position of the genus Jasus among spiny lobsters (family Palinuridae) using a maximum likelihood phylogenetic analysis based on translated mitochondrial protein coding genes (PCG’s). Results Using an in-silico k-mer approach, the haploid nuclear genome size (GS) calculated for J. frontalis ranged between 1.42 Gbp (estimated using k-mer = 54 bp) and 1.65 Gbp (with k-mer = 18). Our GS estimates are well below the GS (= 4.56 Gbp) determined for the same species using flow cytometry. In J. frontalis , the circular mitochondrial genome is 15,514 bp in length and contains 22 transfer (tRNA) genes, 13 PCGs, and two ribosomal RNA genes (12 S and 16 S ribosomal RNA). In the nuclear genome of J. frontalis , repetitive elements content varied between 41% (with k-mer = 54) and 64% (using k-mer = 18 bp). Nearly a third (64.94%) of the transposable elements were not annotated. Among annotated transposable elements, Long Interspersed Nuclear Elements (LINEs, 12.64%), DNA transposons (7.35%), and Long Terminal Repeats (LTRs, 5.44%) were the most common. Less abundant transposable elements included Rolling Circles (1.3%), Short Interspersed Nuclear Elements (SINEs, 0.64%), Satellite DNA (0.43%), and simple repeats (0.42%), among others. A phylomitogenomic analysis based on PCGs indicated supported the monophyletic status of the infraorder Achelata and the superfamilies Paniluridae and Syllaridae. The genus Jasus together with Sagmariasus verreauxi were recovered as a monophyletic clade that also provided support for the monophyletic status of lobsters that do not produce sound (“Silentes”). Conclusion The genomic resources developed in this study will support conservation strategies and efficient fisheries management in this spiny lobster that is likely overexploited.

Understanding the mechanisms of sexual development would pave the way for producing mono-sex populations to aid the aquaculture industry. This study investigates the functions of the Y-linked iDmrt1 paralogue (Po-iDMY) and insulin-like androgenic gland hormone (Po-IAG) in the process of sexual development in the tropical rock lobster, Panulirus ornatus (TRL). Previously, we identified that Po-iDMY, a male-specific heterogametic (Y-linked) paralogue of the autosomal Po-iDmrt1 found in TRL, is a second sex-linked iDmrt gene identified in invertebrates. Using 5′ and 3′ rapid amplification of cDNA ends and data from a draft male genome (with an assembly genome size of approximately 2.446 Gbp and 87% BUSCO completeness), we obtained the full-length Po-iDMY gene (encoding a protein of 312 amino acids). A 411 bp male-specific sequence located at the 3′ untranslated region of Po-iDMY mRNA was used as a sex marker, which was reported for the first time in our draft genome. However, Po-iDMY is not a master sex-determining factor since it was not expressed across developmental stages of embryos, juveniles and adults. Instead, we silenced Po-IAG at an early juvenile stage, generating two potential neo-females, implying that sexual manipulation could be a promising technique in TRL.

Panulirus ornatus, the ornate spiny lobster, is a stenohaline weak hyper-osmoregulator, yet its osmoregulatory response to salinity stress remains poorly understood. This study investigated six osmoregulatory genes—Na+/K+-ATPase (nka), V-type H+-ATPase (vhe), Na+/HCO3− exchanger (nbc), Na+/K+/2Cl− co-transporter (nkcc), Na+/H+ exchanger (nhe), and carbonic anhydrase (ca)—in juvenile gills exposed to 25 ppt, 34 ppt (control), and 40 ppt salinities during acute (48 h) and chronic (>38 d) phases. Transcriptome analysis revealed that all genes were unresponsive following either 25 ppt or 40 ppt salinity acute exposure. However, nkcc showed a tendency toward for upregulation under 25 ppt salinity during acute exposure. Additionally, glutathione S-transferase and putative ferrous reductase 1 were upregulated under 25 ppt salinity, suggesting increased metabolic demand. In contrast, glutathione peroxidase and an ammonia transporter were upregulated in 40 ppt salinity, indicating protein catabolism. Quantitative PCR confirmed nkcc- and nka upregulation under chronic 25 ppt salinity. Vhe, nbc, nhe and ca showed no response, and 40 ppt salinity did not affect the six target genes. These findings suggest P. ornatus relies on nkcc- and nka-mediated ion transport and lacks mechanisms to tolerate high salinity, resulting in reduced growth and survival. These findings define optimal salinity range for aquaculture (25–34 ppt), highlighting the need to avoid high-salinity stress in lobster water quality management

Many marine animals have evolved sensory abilities to use electric and magnetic cues in essential aspects of life history, such as to detect prey, predators and mates as well as to orientate and migrate. Potential disruption of vital cues by human activities must be understood in order to mitigate potential negative influences. Cable deployments in coastal waters are increasing worldwide, in capacity and number, owing to growing demands for electrical power and telecommunications. Increasingly, the local electromagnetic environment used by electro- and magneto-sensitive species will be altered. We quantified biologically relevant behavioural responses of the presumed, magneto-receptive American lobster and the electro-sensitive Little skate to electromagnetic field (EMF) emissions of a subsea high voltage direct current (HVDC) transmission cable for domestic electricity supply. We demonstrate a striking increase in exploratory/foraging behaviour in skates in response to EMF and a more subtle exploratory response in lobsters. In addition, by directly measuring both the magnetic and electric field components of the EMF emitted by HVDC cables we found that there were DC and unexpectedly AC components. Modelling, restricted to the DC component, showed good agreement with measured results. Our cross-disciplinary study highlights the need to integrate an understanding of the natural and anthropogenic EMF environment together with the responses of sensitive animals when planning future cable deployments and predicting their environmental effects.

Marine seismic surveys are used to explore for sub-seafloor oil and gas deposits. These surveys are conducted using air guns, which release compressed air to create intense sound impulses, which are repeated around every 8–12 seconds and can travel large distances in the water column. Considering the ubiquitous worldwide distribution of seismic surveys, the potential impact of exposure on marine invertebrates is poorly understood. In this study, egg-bearing female spiny lobsters ( Jasus edwardsii ) were exposed to signals from three air gun configurations, all of which exceeded sound exposure levels (SEL) of 185 dB re 1 μPa 2 ·s. Lobsters were maintained until their eggs hatched and the larvae were then counted for fecundity, assessed for abnormal morphology using measurements of larval length and width, tested for larval competency using an established activity test and measured for energy content. Overall there were no differences in the quantity or quality of hatched larvae, indicating that the condition and development of spiny lobster embryos were not adversely affected by air gun exposure. These results suggest that embryonic spiny lobster are resilient to air gun signals and highlight the caution necessary in extrapolating results from the laboratory to real world scenarios or across life history stages.

Understanding mechanisms of thermal sensitivity is key to predict responses of marine organisms to changing temperatures. Sustaining heart function is critical for complex organisms to oxygenate tissues, particularly under temperature stress. Yet, specific mechanisms that define thermal sensitivity of cardiac function remain unclear. Here we investigated whole animal metabolism, cardiac performance and mitochondrial function in response to elevated temperatures for temperate, subtropical and tropical spiny lobster species. While oxygen demands increased with rising temperatures, heart function became limited or declined in all three species of lobsters. The decline in cardiac performance coincided with decreases in mitochondrial efficiency through increasing mitochondrial proton leakage, which predicts impaired compensation of ATP production. Species differences were marked by shifts in mitochondrial function, with the least thermal scope apparent for tropical lobsters. We conclude that acute temperature stress of spiny lobsters, irrespective of their climatic origin, is marked by declining cellular energetic function of the heart, contributing to an increasing loss of whole animal performance. Better understanding of physiological thermal stress cascades will help to improve forecasts of how changing environmental temperatures affect the fitness of these ecologically and commercially important species.

The effects of anthropogenic aquatic noise on marine invertebrates are poorly understood. We investigated the impact of seismic surveys on the righting reflex and statocyst morphology of the palinurid rock lobster, Jasus edwardsii , using field-based exposure to air gun signals. Following exposure equivalent to a full-scale commercial assay passing within 100–500 m, lobsters showed impaired righting and significant damage to the sensory hairs of the statocyst. Reflex impairment and statocyst damage persisted over the course of the experiments—up to 365 days post-exposure and did not improved following moulting. These results indicate that exposure to air gun signals caused morphological damage to the statocyst of rock lobsters, which can in turn impair complex reflexes. This damage and impairment adds further evidence that anthropogenic aquatic noise has the potential to harm invertebrates, necessitating a better understanding of possible ecological and economic impacts.

The molecular understanding of crustacean metamorphosis is hindered by small sized individuals and inability to accurately define molt stages. We used the spiny lobster Sagmariasus verreauxi where the large, transparent larvae enable accurate tracing of the transition from a leaf-shaped phyllosoma to an intermediate larval-juvenile phase (puerulus). Transcriptomic analysis of larvae at well-defined stages prior to, during and following this transition show that the phyllosoma-puerulus metamorphic transition is accompanied by vast transcriptomic changes exceeding 25% of the transcriptome. Notably, genes previously identified as regulating metamorphosis in other crustaceans do not fluctuate during this transition but in the later, morphologically-subtle puerulus-juvenile transition, indicating that the dramatic phyllosoma-puerulus morphological shift relies on a different, yet to be identified metamorphic mechanism. We examined the change in expression of domains and gene families, with focus on several key genes. Our research implies that the separation in molecular triggering systems between the phyllosoma-puerulus and puerulus-juvenile transitions might have enabled the extension of the oceanic phase in spiny lobsters. Study of similar transitions, where metamorphosis is uncoupled from the transition into the benthic juvenile form, in other commercially important crustacean groups might show common features to point on the evolutionary advantage of this two staged regulation.

Sociality has evolved in a wide range of animal taxa but infectious diseases spread rapidly in populations of aggregated individuals, potentially negating the advantages of their social interactions. To disengage from the coevolutionary struggle with pathogens, some hosts have evolved various forms of \"behavioral immunity\"; yet, the effectiveness of such behaviors in controlling epizootics in the wild is untested. Here we show how one form of behavioral immunity (i.e., the aversion of diseased conspecifics) practiced by Caribbean spiny lobsters (Panulirus argus) when subject to the socially transmitted PaV1 virus, appears to have prevented an epizootic over a large seascape. We capitalized on a \"natural experiment\" in which a die-off of sponges in the Florida Keys (USA) resulted in a loss of shelters for juvenile lobsters over a ~2500km2 region. Lobsters were thus concentrated in the few remaining shelters, presumably increasing their exposure to the contagious virus. Despite this spatial reorganization of the population, viral prevalence in lobsters remained unchanged after the sponge die-off and for years thereafter. A field experiment in which we introduced either a healthy or PaV1-infected lobster into lobster aggregations in natural dens confirmed that spiny lobsters practice behavioral immunity. Healthy lobsters vacated dens occupied by PaV1-infected lobsters despite the scarcity of alternative shelters and the higher risk of predation they faced when searching for a new den. Simulations from a spatially-explicit, individual-based model confirmed our empirical results, demonstrating the efficacy of behavioral immunity in preventing epizootics in this system.

Spiny lobsters use their chemical senses to acquire resources such as shelter and food, avoid predators, and interact with conspecifics. However, little is known about if and how these responses change over developmental stages. Here, we used early benthic juvenile stage Caribbean spiny lobsters, Panulirus argus , in calcium imaging studies to investigate physiological properties of olfactory receptor neurons in the olfactory organ, i.e ., the antennules, and in behavioral studies to characterize chemically triggered responses. The basic structural organization of the antennules is similar in early benthic juvenile, older juvenile, and adult lobsters. Our calcium imaging studies show that the olfactory receptor neurons of both life stages have generally similar patterns of spontaneous activity, tuning characteristics, sensitivity, and kinetic parameters of responses to chemicals. Our behavioral studies show that early benthic juvenile spiny lobsters have similar behaviors to adults in that they produce currents following stimulation with food-related chemicals, navigate through the chemical plumes to locate the source of food-related chemicals, show alarm responses to conspecific hemolymph, and groom their antennules following stimulation with L-glutamate. Our findings suggest that features of the olfactory organ and its sensory neurons and the behavioral patterns are generally similar across developmental stages, making early benthic juvenile lobsters a favorable model for studying chemosensory transduction, coding mechanisms, and chemical-driven behaviors. The smaller scale of early benthic juvenile lobsters allows the use of compact, miniature benchtop laboratory setups, offering significant flexibility for medium-throughput basic and applied studies.