Panulirus Argus Research Articles

Displaced juvenile and subadult Caribbean spiny lobsters show strong orientation toward home dens

Caribbean spiny lobsters are known to undergo migration as adults, but the dispersal and homing ability of subadults and juveniles is not well characterized. Given that settlement habitat for juveniles is inshore seagrass / hardbottom and reproductive habitat is offshore coral reefs, dispersal during ontogeny serves as a bottleneck potentially limiting adult population density. Previous studies have examined factors associated with movement and den selection by juvenile lobsters such as shelter type, predators, and conspecific density. Their attraction to odors of healthy conspecifics plays a significant role in aggregation of lobsters in casitas and traps. But what is unknown is whether juvenile lobsters possess the map and compass orientation found in adults. To examine the ontogeny of homing ability, we conducted multiple mark / displace tracking studies using acoustic telemetry in juvenile hardbottom and subadult coral patch reef habitats. All lobsters regardless of size tend to relocate to new crevice shelters when handled, even if returned to their original shelter. Thus, for non-displaced lobsters tagged and returned to their point of capture, distance and angle travelled appears to be random with distance increasing as function of body size. However, for juvenile and subadult lobsters tagged and displaced away from their point of capture, the distance and angle travelled when released is significantly directed toward the point of capture. Thus, it appears that the map and compass ability of Caribbean spiny lobsters appears early in ontogeny and may allow for individuals to safely explore unfamiliar locations while retaining knowledge of how to return to known shelter. This ability to expand their known habitat map while maintaining knowledge of critical diurnal shelter locations is expected to facilitate their ontogenetic dispersal to adult habitat.

Gastric mill ossicles record chronological age in the Caribbean spiny lobster (Panulirus argus)

Information on individual age and size relationships is crucial for sustainable management of fished populations. Previous research has indicated it may be possible to directly age crustaceans by counting annular bands deposited within gastric mill ossicles. The method has been applied to multiple crustacean species; however, its applicability has been controversial because studies have shown gastric mill ossicles are reworked and/or replaced during ecdysis. Over the last 8 years, we have refined and improved upon methods of processing gastric mill ossicles and investigated the validity of this method for ageing Caribbean spiny lobster (Panulirus argus) using captive-raised animals of known age from the Florida Keys (USA). Although the biological process that creates annular bands within gastric mill ossicles remains unclear, validation of the method for P. argus based on known-age lobsters from 10 months–5.5 years old (n = 33) confirms that the deposition of bands correlates with chronological age. We compared precision and accuracy of age estimates for ossicles processed using two imaging techniques (transmitted vs. reflected light) and found that transmitted light provided the best images for ageing P. argus. The mean coefficient of variation (CV) of age estimates between two readers was 20.2 %. The consensus age estimates provided by the readers were, on average, within 0.5 years of the known age and overall, 94 % of consensus age estimates from readers were within 1 year of the known age. We also compared lobsters of the same size but different age as well as those of the same age but different size to address whether the number of endocuticular bands in the ossicle is a measure of true chronological age or simply related to the size of the animal. Our results suggest that the gastric mill ossicles record chronological age in P. argus, providing a reliable ageing method with which to inform age-based management of the Caribbean spiny lobster population. Future research is needed to understand the mechanism that controls the deposition of endocuticular bands within the crustacean gastric mill ossicles and to determine the applicability of the method for other crustaceans.

Complete genome of Vibrio harveyi isolate K2014767 from the hepatopancreas of captive Caribbean spiny lobster (Panulirus argus).

The complete genome sequence is reported for Vibrio harveyi isolate K2014767, isolated from a captive Caribbean spiny lobster (Panulirus argus) during a species-specific mortality event in a public display aquarium in the United States.

Developing a population assessment for Caribbean spiny lobster Panulirus argus in the United States Virgin Islands: lessons learned

The Caribbean spiny lobster (Panulirus argus) is one of the most important fisheries in the US Virgin Islands. Low densities and life-history characteristics of lobsters have made reliable surveys in the region notoriously difficult, contributing to sparse and inconsistent fisheries- independent datasets to inform management decisions. Many existing and historical surveys are limited in their temporal and spatial coverage. In 2019, the National Park Service initiated a long-term monitoring effort of spiny lobsters in Buck Island Reef National Monument and Salt River National Historical Park and Ecological Preserve, St. Croix, US Virgin Islands, and Virgin Islands National Park, St. John, US Virgin Islands. Initial surveys show both density (3.06–7.07 lobsters ha –1) and occupancy (0.11–0.12 sites with lobster) are low and not significantly different between the three parks. While survey efforts are currently focused on national parks, the 50 × 50 m gridded sample frame and stratification scheme are adaptable to the wider US Caribbean region, modelled after the multi-agency design to monitor reef fish with the National Coral Reef Monitoring Program. With the same survey footprint as reef fish surveys, the two methods could conceivably be co-located in the future, improving cost-efficiency and overall data quality. If expanded, this methodology could provide regional fishery managers with much needed density indices, though future surveys would benefit from a greater sample size or by supplementing with other methods that increase the number of observed lobsters to allow for robust size-frequency analyses.

Transcriptomic evidence of a fourth mininucleovirus (Mininucleoviridae): A rapidly growing family among the Nucleo-Cytoplasmic Large DNA viruses (NCLDVs)

The Mininucleoviridae are crustacean-infecting viruses thought to drive mortality across aquatic biomes. Three have been characterised from Carcinus maenas, Panulirus argus, and Dikerogammarus haemobaphes. We screened 202 SRA datasets (NCBI) for novel mininucleoviruses from 44 amphipod species. Three metatranscriptome datasets from Gammarus lacustris contained sequences with similarity to Dikerogammarus haemobaphes mininucleovirus. Assembly resulted in 19 transcripts, 16 were putatively polycistronic. The putative Gammarus lacustris mininucleovirus shares 46 homologues with other mininucleoviruses (similarity range: 24.07 – 78.2 %). The transcripts from this putative virus highlight its likely association with the Mininucleoviridae.

Escape gaps in wire lobster traps reduce bycatch of coral reef fish while maintaining catch of harvestable lobsters in Florida’s Caribbean spiny lobster (Panulirus argus), fishery

Escape gaps are a tool commonly used to reduce the catch of sublegal-size animals and bycatch in crustacean trap fisheries. In Florida’s Caribbean spiny lobster (Panulirus argus) commercial trap fishery, traps are baited with live, sublegal-size lobsters, which precludes the use of escape gaps sized to exclude capture of undersize lobsters. Both wood and wire traps are used in the fishery, but wire traps capture more fish as bycatch than do wood traps. This project was developed and executed cooperatively with commercial fishers to evaluate, for wire lobster traps, the effect of escape gaps on catch rates of bycatch and harvestable lobsters. We tested five wire-trap configurations that included a control trap without escape gaps (i.e., an unmodified commercial trap) and four configurations consisting of a narrow (3.81 cm) or wide (5.40 cm) escape gap, oriented either vertically or horizontally. All traps were fished in the Atlantic Ocean at a deepwater site (ca. 30 m) and a shallow-water (ca. 10 m) site. Control traps and traps with a narrow escape-gap configuration were baited with a live, sublegal-size lobster; traps with a wide escape-gap configuration were baited with a live, legal-size lobster. We compared the number of lobsters caught and coral reef fish bycatch, as well as size frequency distributions of lobster and compressiform fish species, which include fish in the snapper and grouper families, in each trap configuration. Escape-gap traps caught statistically similar numbers of legal-size lobsters in all configurations except the wide horizontal configuration at the deep site. The catch of sublegal-size lobsters was significantly reduced in the wide horizontal and wide vertical escape-gap trap configurations at both sites. Fish bycatch was dominated by compressiform fish of the Haemulidae family and fish bycatch was significantly reduced in all escape-gap trap configurations. Our results suggest that the wide vertical escape-gap configuration maximized both the retention of harvestable lobsters and the escape of sublegal-size lobsters and fish bycatch. Inclusion of any of the escape-gap configurations tested could reduce discard mortality of fish and undersize lobsters, but baiting and trap fishing methods may need to be adjusted to maximize lobster harvest.

Chemical sensing and avoidance of PaV1-infected conspecifics by pueruli post-larvae of the reef-dwelling Caribbean spiny lobster Panulirus argus Latreille, 1804 (Decapoda: Achelata: Palinuridae)

Abstract Little is known about chemical sensing during settlement by pueruli of the Caribbean spiny lobster Panulirus argus Latreille, 1804 and the effect that Panulirus argus virus 1 (PaV1), the first pathogenic virus to infect any spiny lobster, has on settling pueruli. Considering that the avoidance of PaV1-infected lobsters by early-benthic juveniles is well documented and the previously reported costs of close proximity to PaV1-infected early-benthic juveniles (increased mortality risk), pueruli of P. argus should avoid infected conspecifics during settlement. We experimentally tested if pueruli show aversion to PaV1-infected conspecifics. We also re-tested the previously reported effect of red algae (Laurencia spp.) and healthy conspecifics on pueruli settlement decisions. Considering the known benefits of inhabiting red algae and costs of close proximity to conspecific juveniles, pueruli were predicted to be attracted to metabolites produced by red algae and repulsed by metabolites produced by conspecifics. We also predicted that attraction to red algae would decrease or cease if this cue was presented together with cues produced by PaV1-infected conspecifics. Our experiments indicate that pueruli do not avoid metabolites produced by benthic juveniles and are not attracted to metabolites produced by red algae. Importantly, pueruli are attracted to a combination of metabolites produced by red algae and conspecific juveniles but this attraction ceases if conspecifics are PaV1-infected. Our results indicate that PaV1 disrupts habitat selection by settling pueruli and suggest that assumptions about cost and benefits experienced by settling pueruli need to be revisited. Research to improve the understanding of the relationship between recruitment, disease avoidance, and fishery stock in this heavily exploited spiny lobster is needed.

Effects of Cymatocarpus solearis (Trematoda: Brachycoeliidae) on its second intermediate host, the Caribbean spiny lobster Panulirus argus.

Many digenean trematodes require three hosts to complete their life cycle. For Cymatocarpus solearis (Brachycoeliidae), the first intermediate host is unknown; the Caribbean spiny lobster Panulirus argus is a second intermediate host, and the loggerhead turtle Caretta caretta, a lobster predator, is the definitive host. Trophically-transmitted parasites may alter the behavior or general condition of intermediate hosts in ways that increase the hosts' rates of consumption by definitive hosts. Here, we examined the effects of infection by C. solearis on P. argus by comparing several physiological and behavioral variables among uninfected lobsters (0 cysts) and lobsters with light (1-10 cysts), moderate (11-30 cysts), and heavy (>30 cysts) infections. Physiological variables were hepatosomatic index, growth rate, hemocyte count, concentration in hemolymph of cholesterol, protein, albumin, glucose, dopamine (DA) and serotonin (5-HT). Behavioral variables included seven components of the escape response (delay to escape, duration of swimming bout, distance traveled in a swimming bout, swim velocity, acceleration, force exerted, and work performed while swimming). There was no relationship between lobster size or sex and number of cysts. Significant differences among the four lobster groups occurred only in concentration of glucose (lower in heavily infected lobsters) and 5-HT (higher in heavily and moderately infected lobsters) in plasma. As changes in 5-HT concentration can modify the host's activity patterns or choice of microhabitat, our results suggest that infection with C. solearis may alter the behavior of spiny lobsters, potentially increasing the likelihood of trophic transmission of the parasite to the definitive host.

Recruitment of Psostlarval Spiny Lobster, Stone Crabs, and Larval Fish to Back-Reef Nursery Habitats in the Florida Keys, USA

Back reef areas contain a mosaic of relatively shallow habitats that serve as a key nursery for reef species. Expansive back reef habitats in the lower Florida Keys, USA border the Atlantic Ocean and the Gulf of Mexico. A combination of floating, artificial settlement substrates and plankton nets moored in channels connecting coastal waters and back reef habitats quantified spiny lobster (Panulirus argus) and stone crab (Menippe sp.) settlement, and larval fish ingress, respectively, during 1999 and 2002–2003. The key finding was that channels connecting coastal waters with back reef areas serve as conduits for ingressing larval spiny lobster, stone crabs, and fishes. The results highlight the important role of Atlantic Ocean sources of spiny lobster pueruli and lutjanid fish larvae in this back reef system, and Gulf sources of stone crabs. Spiny lobster settlement generally peaked in August and September and occurred on the Atlantic Ocean side of this back reef system; settlement of stone crabs peaked at the same time as spiny lobster yet occurred predominantly on the Gulf side. Recruitment of larval fish was higher on the Atlantic than the Gulf side, with 37% of fish species collected nearly exclusively on the Atlantic side and about 25% collected nearly exclusively on the Gulf side. Channel habitats appear critical to supporting the nursery role of back reef habitats and should receive special consideration in future ecosystem studies, as well as during spatial planning and evaluations of essential fish habitat.

Detection and diagnosis of Panulirus argus virus 1 in captive spiny lobsters using qPCR in conjunction with histopathology and transmission electron microscopy.

Panulirus argus virus 1 (PaV1) is the first and only naturally occurring pathogenic virus described in the Caribbean spiny lobster, Panulirus argus. PaV1 infection in decapod species that commonly co-occur with P. argus, including the spotted spiny lobster Panulirus guttatus, has not been previously described. In 2016, 14 Caribbean and 5 spotted spiny lobsters were collected near Summerland Key, Florida, to supplement the resident population of the Audubon Aquarium of the Americas in New Orleans, Louisiana. After 5 months in quarantine, Caribbean and spotted spiny lobsters began to exhibit clinical signs of lethargy and dying in the molt. Initial histologic evaluation revealed intranuclear inclusion bodies in circulating hemocytes in the spongy connective tissue of the epidermis, suggesting a viral infection. Samples of hepatopancreas and hemolymph from deceased Caribbean and spotted spiny lobsters tested negative for white spot syndrome virus and positive for PaV1 using real-time quantitative polymerase chain reaction (qPCR). Intranuclear, eosinophilic to amphophilic, Cowdry type A inclusion bodies observed primarily within fixed phagocytes and circulating hemocytes in the hepatopancreas of freshly euthanized Caribbean spiny lobsters were consistent with PaV1 infection. Transmission electron microscopy revealed that hemocytes associated with hepatopancreatic tubules contained viral inclusions with location, size, and morphology consistent with previously described PaV1 infection. These findings highlight the significance of using molecular diagnostics in conjunction with histopathology and electron microscopy in the investigation and diagnosis of PaV1 in spiny lobsters. Further study is required to investigate the relationship of PaV1-associated mortality events and microscopic lesions in the spotted spiny lobster.

The effect of the egg-predator Carcinonemertes conanobrieni on the reproductive performance of the Caribbean spiny lobster Panulirus argus

BackgroundThe Caribbean spiny lobster Panulirus argus is heavily fished throughout its Greater Caribbean and Gulf of Mexico distribution, suggesting a heightened susceptibility to a fisheries collapse. In 2017, a nemertean worm, Carcinonemertes conanobrieni was described from ovigerous females of P. argus in Florida, USA. A year later, the presence of the same egg predator was recorded along the southern Caribbean coast (Colombia). The effect of this egg predator on the reproductive performance, including fecundity, embryo mortality, and reproductive output, of its host is unknown. This study tested whether C. conanobrieni affects embryo mortality, fecundity, and reproductive output in brooding females of P. argus.ResultsArtisan fishers caught 90 ovigerous lobsters near Pueblo Viejo, Magdalena, Colombia. Each ovigerous female was examined for the presence/absence of the egg predator. Lobster egg mortality (%), fecundity (nº eggs female−1), and reproductive output (%) were estimated. Prevalence of C. conanobrieni in the studied population was 87.78%. The mean intensity of C. conanobrieni (all life stages) in the population was 11.68 (± 1.98) egg predators per brood mass sample. Infected females brooding late-stage embryos exhibited lower fecundity, lower reproductive performance values, and higher embryo mortality compared to infected females brooding early-stage embryos. Embryo stage and worm infection level negatively impacted fecundity and reproductive output. Worm infection level and the number of adult nemertean worms also negatively affected embryo mortality.ConclusionsThese results demonstrate an adverse effect of C. conanobrieni on the reproductive performance of P. argus. The interactive impact of this egg predator, natural stressors, and anthropogenic stressors on individual P. argus reproductive performance could facilitate losses at large-scale fisheries levels.

The C-Terminus of Panusin, a Lobster β-Defensin, Is Crucial for Optimal Antimicrobial Activity and Serum Stability.

β-defensins are one of the most abundant and studied families of antimicrobial peptides (AMPs). Because of their selective toxicity to bacterial membranes and a broad spectrum of microbicidal action, β-defensins are regarded as potential therapeutic agents. This work focuses on a β-defensin-like AMP from the spiny lobster Panulirus argus (hereafter referred to as panusin or PaD). This AMP is structurally related to mammalian defensins via the presence of an αβ domain stabilized by disulfide bonds. Previous studies of PaD suggest that its C-terminus (Ct_PaD) contains the main structural determinants of antibacterial activity. To confirm this hypothesis, we made synthetic versions of PaD and Ct_PaD to determine the influence of the C-terminus on antimicrobial activity, cytotoxicity, proteolytic stability, and 3D structure. After successful solid-phase synthesis and folding, antibacterial assays of both peptides showed truncated Ct_PaD to be more active than native PaD, confirming the role of the C-terminus in activity and suggesting that cationic residues in that region enhance binding to negatively charged membranes. On the other hand, neither PaD nor Ct_PaD were hemolytic or cytotoxic in human cells. Proteolysis in human serum was also studied, showing high (>24 h) t1/2 values for PaD and lower but still considerable for Ct_PaD, indicating that the missing native disulfide bond in Ct_PaD alters protease resistance, albeit not decisively. NMR-2D experiments in water agree with the results obtained by circular dichroism (CD), where in SDS micelles, CD showed both peptides adopting an increasingly ordered structure in a hydrophobic environment, in tune with their ability to perturb bacterial membrane systems. In conclusion, while the β-defensin features of PaD are confirmed as advantageous in terms of antimicrobial activity, toxicity, and protease stability, the results of the present work suggest that these same features are preserved, even enhanced, in the structurally simpler Ct_PaD, which must therefore be viewed as a valuable lead for the development of novel anti-infectives.

Vibrio harveyi in a Caribbean spiny lobster (Panulirus argus) with hepatopancreas necrosis.

A Caribbean spiny lobster, Panulirus argus, was submitted for necropsy after a number of species-specific fatalities in a public aquarium. The hemolymph was opaque and did not clot and the hepatopancreas had multiple foci of necrosis centered on gram-negative bacteria. Pure cultures of Vibrio harveyi were isolated, identified initially by matrix laser desorption ionization-time of flight mass spectrometry, and confirmed by multilocus sequencing of the gyrB, recA, rpoA, and pyrH genes. As Caribbean spiny lobsters continue to be used for consumption and displayed in public aquariums, chronicling potential pathogens is warranted to inform differential diagnoses and to develop management strategies to reduce incidence of infectious disease in captive populations.

Influence of Environmental Factors on Nutritional Condition of Spiny Lobster Panulirus argus (Decapoda: Palinuridae)

Environmental influence on lobster’s physiology is a topic little addressed around the world. We determined the impact of biotic (food availability) and abiotic (temperature, salinity, and dissolved oxygen) environmental factors on nutritional condition of Panulirus argus (Latreille, 1804) from the Caibarien fishing region, Cuba. Eleven sites were sampled from 2010 to 2015, during dry and rainy seasons. Blood Refractive Index (BRI) and Kcl (total weight/carapace length) were used as nutritional condition indicators. Benthic food availability index (BFAI) was also determined. BRI and Kcl were both correlated with BFAI and varied significantly among sites and years. Salinity showed interannual differences, with lowest value in 2013. BFAI gradually increased between 2010 and 2015. Generalized Additive Model (GAM) for Kcl was 84.8% deviance explained (R2 = 77.6%), showing an environmental important influence on lobster’s nutritional condition. “Site”, dissolved oxygen, and BFAI had significant impacts on Kcl. GAM for BRI was 34.6% deviance explained (R2 = 25.3%), only salinity significantly impacted lobster’s blood parameters. Environmental influence in lobster’s nutritional condition was multifactorial and included biotic and abiotic variables. Food availability makes vary BRI and Kcl, nevertheless, they are both sensitive in different way to environmental factors and should have different interpretation.

Artificial shelters and marine infectious disease: no detectable effect of the use of casitas to enhance juvenile Panulirus argus in shelter-poor habitats on a viral disease dynamics.

Casitas, low-lying artificial shelters that mimic large crevices, are used in some fisheries for Caribbean spiny lobsters (Panulirus argus). These lobsters are highly gregarious and express communal defense of the shelter. Scaled-down casitas have been shown to increase survival, persistence, and foraging ranges of juveniles. Therefore, the use of casitas has been suggested to help enhance local populations of juvenile P. argus in Caribbean seagrass habitats, poor in natural crevice shelters, in marine protected areas. Following the emergence of Panulirus argus virus 1 (PaV1), which is lethal to juveniles of P. argus, concern was raised about the potential increase in PaV1 transmission with the use of casitas. It was then discovered that lobsters tend to avoid shelters harboring diseased conspecifics, a behavior which, alone or in conjunction with predatory culling of diseased lobsters, has been proposed as a mechanism reducing the spread of PaV1. However, this behavior may depend on the ecological context (i.e., availability of alternative shelter and immediacy of predation risk). We conducted an experiment in a lobster nursery area to examine the effect of the use of casitas on the dynamics of the PaV1 disease. We deployed 10 scaled-down casitas per site on five 1-ha sites over a reef lagoon (casita sites) and left five additional sites with no casitas (control sites). All sites were sampled 10 times every 3-4 months. Within each site, all lobsters found were counted, measured, and examined for clinical signs of the PaV1 disease. Mean density and size of lobsters significantly increased on casita sites relative to control sites, but overall prevalence levels remained similar. There was no relationship between lobster density and disease prevalence. Dispersion parameters (m and k of the negative binomial distribution) revealed that lobsters tended to avoid sharing natural crevices, but not casitas, with diseased conspecifics. These results confirm that casitas provide much needed shelter in seagrass habitats and that their large refuge area may allow distancing between healthy and diseased lobsters. On eight additional sampling times over two years, we culled all diseased lobsters observed on casita sites. During this period, disease prevalence did not decrease but rather increased and varied with site, suggesting that other factors (e.g., environmental) may be influencing the disease dynamics. Using scaled-down casitas in shelter-poor habitats may help efforts to enhance juvenile lobsters for conservation purposes, but monitoring PaV1 prevalence at least once a year during the first few years would be advisable.

Thermal optimality and physiological parameters inferred from experimental studies scale latitudinally with marine species occurrences

Ocean warming is expected to occur due to anthropogenic climate change bringing a spatial shift of marine communities. Experimental data that characterize the aerobic power budget via an aerobic scope, thermal metabolic scope, or thermal preferences have been proposed as tools that can describe species distribution since they characterize species fitness or performance under different temperatures. This study tested the potential relationship between observed occurrences and different physiological studies in the Americas for 11 commercially important species in Mexico. Projections were also developed for Mexico's exclusive economic zone under different climate warming scenarios. The physiological data were fitted from optimum up to pejus temperatures and projected to sea surface temperatures for present (2003–2014) and Representative Concentration Pathway (RCP) scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5) for the period 2040–2050 and 2090–2100. For species with wide distributions in the Americas, the number of occurrences reported decreases at higher latitudes related to the decrease in species performance calculated from laboratory experiments. In addition, higher species occurrences are usually reported around optimum temperatures. Overall, the results suggest that pejus temperatures likely restrict latitudinal distribution, at least for widely distributed taxons. Regarding Mexican projections, the results varied widely by species. For example, in the Atlantic Ocean, Octopus maya and Panulirus argus are vulnerable to warming scenarios, while Centropomus undecimalis is not. Interestingly, northern Campeche Bank, the Gulf of California, and Western Baja California may act as thermal refugia for marine species indicating they could be assigned as protected areas to support fisheries throughout the Mexican exclusive economic zone. This research adds to the increasing evidence of the relationship between thermal niche and wild population distribution.

Acoustic properties and shallow water propagation distances of Caribbean spiny lobster sounds (Panulirus argus)

Marine crustaceans produce broadband sounds that are useful for passive acoustic monitoring to support conservation and management efforts. However, the propagation characteristics and detection ranges of their signals are poorly known, limiting our leveraging of these sounds. Here, we used a four-hydrophone linear array to measure source levels (SLs) and sound propagation from Caribbean spiny lobsters (Panulirus argus) of a wide range of sizes within a natural, shallow water habitat (3.3 m depth). Source level in peak-peak (SLpp) varied with body size; larger individuals produced SLpp up to 166 dB re 1 μPa. However, transmission losses (TL) were similar across all sizes, with a global fitted TL of 12.1 dB. Correspondingly, calculated detection ranges varied with body size, ranging between 14 and 364 m for small and large individuals (respectively). This increased up to 1612 m for large spiny lobsters when considering lower ambient noise levels. Despite the potential ease of tank studies, our results highlight the importance of empirical in situ sound propagation studies for marine crustaceans. Given the important ecological and economic role of spiny lobsters, these data are a key step to supporting remote monitoring of this species for fisheries management and efforts to acoustically quantify coral reefs' health.

Long-term variations in nutritional condition of Panulirus argus (Decapoda: Palinuridae) in Cuba: analytical and morphological approaches

Nutritional condition indices have been frequently used as morphophysiological indicators to study variations on lobster's physiology and energy reserves. This study was aimed to determine long-term spatio-temporal variations in nutritional conditions of Panulirus argus (hereinafter – lobster), considering two indices, namely the analytic Blood Refractive Index (BRI) and the morphometric Kcl (total weight / carapace length relationship). Information from eleven sites in the Caibarién region, sampled in 2010–2015, and twelve sites in the Batabanó region, sampled in 2011–2017, were named as the Current Period. Morphometric data for Kcl estimation, including 1987–1988 in the Caibarién region, and 1981–1993 in the Batabanó region, were grouped as the Past Period. Temporary variations were determined comparing Past and Current periods at each region. Spatial variations were determined by comparing the data between the two regions. For analysed lobsters in the Current period, we determined BRI = 14.3, Kcl = 7.0 in the Caibarién region, and BRI = 15.2. Kcl = 7.0 in the Batabanó region. For the Past period, the Kcl value was 5.8 and 6.3 in the Caibarién and Batabanó region, respectively. Both Kcl and BRI indices were higher for male individuals. This could be associated with the reproductive process, and intrinsic morphometric differences between sexes could influence though. Morphometric parameters were higher for the Current Period. Spatial variations of morphometric parameters were significantly different for the Past Period, which were attributed to different environmental conditions in each region. The BRI index was higher in the Batabanó region, which was possibly associated with the better status of the benthic communities and the better water quality. Present results contribute to understanding lobster's nutritional condition in natural habitats, mainly in the Caibarién region, where few studies have been carried out to date.

Tank acoustics substantially distort broadband sounds produced by marine crustaceans.

Marine crustaceans produce broadband sounds that have been mostly characterized in tanks. While tank physical impacts on such signals are documented in the acoustic community, they are overlooked in the bioacoustic literature with limited empirical comparisons. Here, we compared broadband sounds produced at 1 m from spiny lobsters (Panulirus argus) in both tank and in situ conditions. We found significant differences in all sound features (temporal, power, and spectral) between tank and in situ recordings, highlighting that broadband sounds, such as those produced by marine crustaceans, cannot be accurately characterized in tanks. We then explained the three main physical impacts that distort broadband sounds in tanks, respectively known as resonant frequencies, sound reverberation, and low frequency attenuation. Tank resonant frequencies strongly distort the spectral shape of broadband sounds. In the high frequency band (above the tank minimum resonant frequency), reverberation increases sound duration. In the low frequency band (below the tank minimum resonant frequency), low frequencies are highly attenuated due to their longer wavelength compared to the tank size and tank wall boundary conditions (zero pressure) that prevent them from being accurately measured. Taken together, these results highlight the importance of understanding tank physical impacts when characterizing broadband crustacean sounds.

Immune Response to Natural and Experimental Infection of Panulirus argus Virus 1 (PaV1) in Juveniles of Caribbean Spiny Lobster.

Simple SummaryExperimental immunological challenges are widely used to corroborate the success of breeding programs for lines resistant to specific pathogens, to test the efficiency of new vaccines, and to improve immunity of cultured animals. The validation of experimental infection protocols is complex because it requires comparison with naturally infected organisms at different stages of the infection. The present study compares the immune response of lobsters under a natural process of viral infection (PaV1), versus the defense response of experimentally infected organisms. Innate immunity for infected lobsters was measured through cellular and plasmatic components. The results indicate that the immune response of organisms naturally or experimentally infected by PaV1 was similar, and provides the bases to corroborate that the immunological challenge was not exacerbated. Appropriate infection protocols can be useful for research aimed at increasing resistance to infectious diseases and reducing the use of antibiotics in aquaculture.Experimental infections have been used to better comprehend the immune system of organisms, and to probe for additives that generate greater resistance and help reduce antibiotic use in aquaculture. We compared the immune response of juveniles of the Caribbean spiny lobster, Panulirus argus, infected naturally with Panulirus argus virus 1 (PaV1) versus organisms infected experimentally, to determine the analogy between both infectious processes. The immunological response was measured by hemagglutination activity, hemocyte count, and total phenoloxidase activity in plasma and hemocytes in 211 individuals that were either naturally infected (110), or had been injected with viral inoculum and followed for six months (101). The samples were classified into the following four groups according to the severity of the infection: 0, uninfected; 1, lightly; 2, moderately; and 3, severely infected), which was determined on the basis of PCR and histological criteria. A permutational MANOVA showed that both the origin (natural and experimental), and the severity of the infection contributed significantly to explain the variation in the immune response of lobsters. The lack of significance of the interaction term indicated that the immunological response changed with the severity of the infection in a similar way, regardless of its origin. The results of the present study suggest that the experimental viral infection of PaV1 produces a defense response similar to the natural pathways of contagion, and provides the bases to validate an immunological challenge protocol for the first time in crustaceans. The discussion includes the perspective of the conceptual models of immune response within an ecological context.