Lobster Panulirus Research Articles

Effect of stocking density on survival and growth of spiny sand lobsters Panulirus homarus in cages at 7‐m depth

AbstractObjectiveThe spiny sand lobster Panulirus homarus is one of the lobster species that has a high price in local and international markets and is economically valuable. The objective of this study was to determine the effect of stocking density on the survival and growth of spiny sand lobsters kept in cylindrical cages (1.00 m high × 1.15 m in diameter) at a depth of 7 m below the water surface, with an average ambient temperature of 29–32°C.MethodsThe 3‐month study was performed in 2022 and had a completely randomized design. There were three treatment groups, each of which had three replications. Stocking densities were 10 lobsters/m2 (10 lobsters/cage) for treatment A, 15 lobsters/m2 (15 lobsters/cage) for treatment B, and 20 lobsters/m2 (20 lobsters/cage) for treatment C. The initial average body weight was 75 g/lobster.ResultThe survival rates for treatment A (mean ± standard error = 91.50 ± 0.25%) and treatment B (93.30 ± 0.51%) were higher than the survival rate for treatment C (86.05 ± 0.45%), but the values were not significantly different. Daily weight gain and the specific daily growth rate for treatments A and C were significantly higher than those of treatment B. The feed conversion ratio was not significantly different among the groups. Total hemocyte count in the hemolymph between treatments A and B as well as initial (day‐0) values were not significantly different, but values for treatments A and B were significantly lower than that for treatment C. The hemolymph glucose value for treatment A was significantly lower than that of treatment C but was not different from that of treatment B.ConclusionThe grow‐out study of spiny sand lobsters at 7‐m depth indicated an optimal stocking density of 15 lobsters/m2. This was supported by several physiological response and production performance parameters, which generally had no significant difference with those of the lower stocking density.

Genomics resources for the Rapa Nui (Eastern Island) spiny lobster Panulirus pascuensis (Crustacea: Decapoda: Achelata)

BackgroundThe Easter Island spiny lobster Panulirus pascuensis (Reed, 1954) or ‘Ura’ in the Rapa Nui language, is a little known species native to the south eastern Pacific Ocean, distributed along the coasts of Easter Island, Pitcairn Island, and the Salas y Gómez Ridge. In Easter Island, P. pascuensis is the target of a small and profitable and probably overexploited fishery. In this study, we profited from a series of bioinformatic analyses to mine biological insight from low-pass short-read next generation sequencing datasets; we have estimated genome size and ploidy in P. pascuensis using a k-mer strategy, discovered, annotated, and quantified mobile elements in the nuclear genome, assembled the 45S rRNA nuclear DNA cassette and mitochondrial chromosome, and explored the phylogenetic position of P. pascuensis within the genus Panulirus using the signal retrieved from translated mitochondrial protein coding genes.ResultsK-mer analyses predicted P. pascuensis to be diploid with a haploid genome size ranging between 2.75 Gbp (with k-mer = 51) and 3.39 Gbp (with k-mer = 18). In P. pascuensis, repetitive elements comprise at least a half and a maximum of three fourths of the nuclear genome. Almost a third (64.94%) of the repetitive elements present in the studied nuclear genome were not assigned to any known family of transposable elements. Taking into consideration only annotated repetitive elements, the most abundant were classified as Long Interspersed Nuclear Elements (22.81%). Less common repetitive elements included Long Terminal Repeats (2.88%), Satellite DNA (2.66%), and DNA transposons (2.45%), among a few others. The 45S rRNA DNA cassette of P. pascuensis was partially assembled into two contigs. One contig, 2,226 bp long, encoded a partially assembled 5′ ETS the entire ssrDNA (1,861 bp), and a partial ITS1. A second contig, 6,714 bp long, encoded a partially assembled ITS1, the entire 5.8S rDNA (158 bp), the entire ITS2, the entire lsrDNA (4,938 bp), and a partial 3′ ETS (549 bp). The mitochondrial genome of P. pascuensis was 15,613 bp long and contained 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA genes (12S ribosomal RNA [rrnS] and 16S ribosomal RNA [rrnL]). A phylomitogenomic analysis based on PCGs retrieved Panulirus pascuensis as sister to a fully supported clade comprising P. cygnus and P. longipes.ConclusionWe expect that the information generated in this study will guide the assembly of a chromosome-level nuclear genome for P. pascuensis in the near future. The newly assembled 45S rRNA nuclear DNA cassette and mitochondrial chromosome can support bioprospecting and biomonitoring of P. pascuensis using environmental DNA. The same elements can help to survey the public market place and detect mislabelling of this and other spiny lobsters. Overall, the genomic resources generated in this study will aid in supporting fisheries management and conservation strategies in this iconic spiny lobster that is likely experiencing overexploitation.

Morphological and molecular identifications of ectoparasites infesting the gills of scalloped spiny lobster Panulirus homarus Linnaeus, 1758

Abstract. Kismiyati, Hidayat YT, Amin M. 2024. Morphological and molecular identifications of ectoparasites infesting the gills of scalloped spiny lobster Panulirus homarus Linnaeus, 1758. Biodiversitas 25: 372-378. Ectoparasite infestation has been reported to cause stress, weaken the immune system, and disturb respiratory systems, which lead to death in cultured spiny lobsters. Many lobster farmers have reported an infestation of ectoparasites in cultured scalloped spiny lobsters in West Nusa Tenggara, Indonesia. However, fewer studies have been conducted to identify the ectoparasite-infesting scalloped spiny lobster cultured in West-Nusa Tenggara Province. Thus, using morphological and molecular approaches, the present study aimed to identify ectoparasites infesting scalloped spiny lobsters (Panulirus homarus Linnaeus, 1758). A total of 30 scalloped spiny lobsters were collected from lobster farmers at Ekas, East Lombok, West Nusa Tenggara, Indonesia, and ectoparasites were observed and identified morphologically under a microscope as well as confirmed using CO1 gene sequences. The results showed that the ectoparasites were morphologically identified as Octolasmis angulata Aurivillius, 1894 and Octolasmis lowei Darwin, 1852. Similarly, based on the mtDNA sequence of the COI region (~721 bp length), the ectoparasite was also referred to O. angulata (95.65% similarity) and Octolasmis lowei (~683 bp length) with a similarity of 98.75%. These results suggest that ectoparasite has become one potential disturbance in lobster aquaculture; therefore, preventing or curing strategies should be developed.

The presence of disease in growing spiny lobster Panulirus spp. in floating net cages at Tanjung Putus Island, Lampung

Spiny lobster is a member of crustaceans that has high economic value. The demand for export markets in Asian, European and American countries as well as locally, is quite high with an expensive selling price. However, there are obstacles that often occur in spiny lobster rearing cultivation, namely infectious diseases that will cause high mortality. The purpose of this study was to investigate infectious diseases in rearing spiny lobster Panulirus spp. that were kept in floating net cages at Tanjung Putus, Lampung. The research method involved sampling five spiny lobsters in floating net cages, observation of clinical symptoms, bacterial isolation, identification of bacteria, detection of Milky Hemolymph Disease of Spiny Lobster (MHD-SL) through polymerase chain reaction (PCR) analysis and histopathology. The sampling location was at PT. Saibatin Perikanan Indonesia. The bacteria Vibrio parahaemolyticus and Vibrio alginolyticus were detected. Five lobsters were infected by MHD-SL, characterized by milky white hemolymph. All five lobster samples were positively infected with Milky Hemolymph Disease of Spiny Lobster (MHD-SL) through PCR analysis. Histopathological observations showed pathological microanatomical changes in the lobster hepatopancreas tissue, indicating that the tissue changes, in the form of encapsulation and infiltration were due to Rickettsia-like bacteria (RLB) infection. The management of spiny lobster stocking density, maintenance biosecurity, and increased lobster immunity must be implemented in order to prevent MHD-SL disease in floating net cages.
 
 Keywords: bacteria, histopathology, MHD-SL, Panulirus spp.
 
 ABSTRAK
 
 Lobster merupakan anggota crustacea yang memiliki nilai ekonomis yang tinggi. Permintaan pasar ekspor pada negara Asia, Eropa, dan Amerika maupun lokal cukup tinggi dengan nilai jual yang mahal. Akan tetapi, terdapat kendala yang sering terjadi pada budidaya pembesaran lobster yaitu infeksi penyakit yang akan menyebabkan tingginya mortalitas Tujuan penelitian ini adalah untuk menginvestigasi penyakit infeksi pada pembesaran lobster Panulirus spp. yang dipelihara di keramba jaring apung Tanjung Putus, Lampung. Metode penelitian ini meliputi pengambilan sampel lobster sebanyak lima ekor dalam karamba jarring apung (KJA), pengamatan gejala klinis, isolasi bakteri, identifikasi bakteri, deteksi Milky Hemolymph Disease of Spiny Lobster (MHD-SL) melalui analisis Polymerase Chain Reaction (PCR), dan histopatologi. Lokasi pengambilan sampel di PT. Saibatin Perikanan Indonesia, Lampung. Terdapat bakteri Vibrio parahaemolyticus dan V. alginolyticus. Lima ekor lobster terinfeksi oleh MHD-SL yang ditandai dengan hemolim berwarna putih susu. Lima sampel lobster positif terinfeksi penyakit Milky Hemolymph Disease of Spiny Lobster (MHD-SL) melalui analisis PCR. Hasil pengamatan histopatologi terdapat perubahan mikroanatomi patologi pada jaringan hepatopankreas lobster menunjukkan bahwa adanya perubahan jaringan berupa enkapsulasi dan infiltrasi karena adanya infeksi Rickettsia-like bacteria (RLB). Pengelolaan kepadatan penebaran lobster, biosekuritas pemeliharaan, dan peningkatan imunitas lobster harus ditingkatkan untuk mencegah penyakit MHD-SL di KJA.
 
 Kata kunci: bakteri, histopatologi, MHD-SL, Panulirus spp.

The impact of fresh and artificial diet on growth and survival rate of spiny lobster, Panulirus homarus reared in floating net cage

Some research found that the growth of lobster was higher when fed with fresh diet than artificial diet. Therefore, the growth of lobster that is fed with combination of fresh and artificial diets need to be observed. This study aimed to evaluate different kinds of feed and its combination on growth and survival rate of spiny lobster Panulirus homarus. This research was designed with three treatments and three replicates, namely: lobster fed with fresh diet (A), lobster fed with artificial diet (dry pellet) (B), and lobster fed with combination of fresh and artificial diets (C). Lobsters with an average weight 100.30 ±0.79 g were reared in floating net cage with dimension 2×2×2 m3 at density 40 lobsters/cage. Lobsters were fed twice a day at 08.30 am and 03.30 pm. Fresh diets that were given contained fresh fish, shrimp, crabs and mussels (3:1:1:1). The observation was conducted for 18 weeks. Results of the experiment were lobsters fed with fresh diets (A) and combination of fresh and artificial diets (C) gave higher specific growth rate (0.62±0.03 %/day and 0.61±0.03 %/day) than lobster fed with artificial diets (B) (0.33±0.01 %/day). There were not significantly differences in survival rate of lobster (p<0.05).

A New Record of Panulirus homarus homarus (Panulirus spp.) from Malaysia Waters with its Molecular Phylogeny

Spiny lobsters Panulirus spp. of the family Palinuridae Latreille, 1802 occupies the shallow tropical and subtropical waters (<100 m depth). These species are ubiquitous and abundant, yet knowledge of its range, biodiversity, and population abundance in Malaysia is limited. Panulirus homarus is listed as “Least Concern” along with other 11 species out of 21 spiny lobster species in the International Union for Conservation of Nature and Natural Resources (IUCN) red list in 2022. A total of five species were reported from Malaysia waters. Whilst, this study reports the sixth spiny lobster species, Panulirus homarus homarus, with morphology and molecular genetic information (Cytochrome oxidase I (COI) gene) provided. The p-distance within P. h. homarus was 0.2 – 0.6%, n = 12; between P. h. homarus with P. h. rubellus and P. homarus “Brown” was 6.4 – 6.8%, n = 12 and 0.8 – 3.3%, n = 12, respectively. Intra-species p-distance within Panulirus spp. was below 3%, while inter-species was above 10%. This validates the collected specimen as P. h. homarus and P. h. rubellus is the subspecies, but leaving P. h. “Brown” taxonomic status unclear. Thus, genetic information is important in solving many of these systematic and taxonomic problems, because often these species are difficult to distinguished based on morphological criteria. A key to all Panulirus spp. identified in Malaysia waters was constructed. This study updates the marine biodiversity list in Malaysia, where the acquisition of biological knowledge is vital to the protection of the world’s natural resources as well as to the sustainable management of spiny lobster fisheries.

Nitrogen excretion by the lobsters Panulirus ornatus and Thenus australiensis and uptake by the brown algae Sargassum siliquosum: Implications for integrated recirculated aquaculture systems

Farming extractive species such as macroalgae that take up nitrogen (N), with fed species (e.g., lobsters, finfish, prawns) is termed integrated multi-trophic aquaculture (IMTA). In recirculating aquaculture systems (RAS), high concentrations of nitrogenous waste can become toxic to the fed species and macroalgae offers a method of mitigating N waste. To utilise macroalgae as a biofilter for N waste, an understanding of their N ecophysiology of both the fed and extractive species is needed. In this study we first determine the ammonium and urea excretion rates for emerging aquaculture candidates the tropical rock lobsters, Panulirus ornatus (TRL) and slipper lobster, Thenus australiensis (SL). Using multiple flask uptake experiments, we then determined the N ecophysiology of the tropical brown macroalga, Sargassum siliquosum, to assess its potential use as a biofilter in a lobster RAS. Routine (basal) N excretion was predominantly ammonium with only a minor contribution of urea (8 and 13% for TRL and SL respectively). For both lobster species, ammonium and urea excretion substantially increased post-prandial, peaking at levels 3.6 times greater than basal amounts for TRL and 3.2 times greater for SL, and remained elevated for between 32 and 38 h. Uptake of both ammonium and nitrate by S. siliquosum showed saturating kinetics, where the kinetic parameter Vmax is the maximum rate of uptake, Ks is the half-saturation constant and the Vmax:Ks-ratio is a proxy for the algae's affinity of uptake for that respective nutrient: for ammonium Vmax = 110.9 μmoles g−1 dry weight (DW) h−1 and Ks = 37.9 μM and for nitrate Vmax = 152.7 μmoles g−1 DW h−1 and Ks = 58.52 μM. Urea uptake was highly variable with both positive and negative (i.e. urea release from tissue) rates recorded; when positive values were considered, Vmax = 55.5 μmoles g−1 DW h−1 and Ks = 17.65 μM. We used uptake and excretion rates from our study to derive a unit mass stocking ratio of algae to lobster (algae: animal) to offset N pollution in RAS. The ratios of TRL to algae to offset NH4+ and urea post-prandial were 5.15E-04 and 3.09E-04 respectively and for SL, 4.46E-04 and 6.31E-04 respectively. The findings serve as a reference for future studies on integrating Sargassum species into RAS and IMTA systems.

Growth performance and survival rate of spiny lobster Panulirus homarus (Linnaeus, 1758) with formulated feeding enriched by spinach extract

Abstract. Lubis AS, Efrizal, Syaifullah, Rusnam, Nurmiati, Puari AT. 2023. Growth performance and survival rate of spiny lobster Panulirus homarus (Linnaeus, 1758) with formulated feeding enriched by spinach extract. Biodiversitas 24: 6010-6016. In the context of spiny lobster Panulirus homarus (Linnaeus, 1758) aquaculture and marine conservation, assessing factors that influence growth and survival is critical. Spinach extract can be added as a feed additive to enhance the growth and survival rate of lobsters. This study aimed to analyze the effect of formulated feed enriched with spinach extract on spiny lobsters' growth and survival performance. A completely randomized design with five treatments and five replications: formulated feed with spinach extract 0 mg (Feed A1), 0.4 mg (Feed A2), 0.5 mg (Feed A3), 0.6 mg (Feed A4), and 0.7 mg (Feed A5) were used. The result showed that the formulated feed enriched with spinach extract had a significant effect on absolute weight, specific growth rate, length, and width of the carapace in growth performance (P<0.05) but had no significant on the survival rate and the molting frequency (P>0.05). The best result was treatment A3, adding 0.5 g of spinach extract to lobster feed with absolute weight 39.67±6.20 g, length of carapace 0.46±0.06 cm, width of carapace 0.28±0.05 cm, specific growth rate 0.38±0.06% day-1, molting frequency 1.00±0.00 times lobster-1, and survival rate 100±0.00%. The Spinach extract of 0.5 mg was the best for the survival and growth of the lobster (Duncan's test). The chemical of the feed showed that the tested feed met the nutritional needs of lobsters with a protein content of 39.74-42.60%. However, the number of amino acids in the best test feeds was still low quantity compared to several other studies, so the growth of lobsters was still slow. Based on research results, enriched 0.5 g of spinach extract to formulated feed is the best result for increasing the growth and survival rate of lobsters.

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.

Growth Response of Lobster Panulirus Homarus Reared in Tanks and in Floating Net Cages Fed with Compound and Fresh Feed

Feeding efficiency is an important factor that supports the success of lobster grow-out culture. This study aimed to investigate growth of different sex of lobsters after being fed with combination of compound and fresh feed in indoor tanks (experiment-1) and growth of male lobster fed with different co-feeding diets in net floating cages (experiment-2). In experiment-1, five replicates of ten lobsters (191.1 ± 18.1 g) for each different sex (i.e., all males, males and females, and all females) were reared in 2 × 2 × 1 m3 tanks with flow through water system and fed with combination of compound (75%) and fresh feed (25%) for 120 days. In experiment-2, four replicates of 20 all male lobsters (183.6 ± 17.6 g) were reared in 12 net cages of 2 × 2 × 2.5 m3 and were fed with compound feed only, compound feed (75%) and fresh feed (25%), and compound feed (75%) with mussel meat (25%) for 120 days. Experiment-1 showed that growth (quantified as weight gain) of all male lobsters was the highest (59.4 ± 10.0 g). Experiment-2 showed that compound feed combined with fresh feed resulted in higher growth of lobster (0.73 ± 0.17 g) than 100% compound feed. There was no difference in survival rate of lobster among the treatment in both experiments with 94 – 100% in experiment-1 and 75.2 to 85.0% in experiment-2. The mortality of lobster caused by Milky Hemolymph Disease (MHD) in floating cage was found higher than in indoor tanks.

Identification and Physiological Assays of Crustacean Hyperglycemic Hormones in the Japanese Spiny Lobster, Panulirus japonicus.

The Japanese spiny lobster Panulirus japonicus lives on rocky shores and is mainly distributed along the Pacific coast around Japan. Due to the high demand for it, the development of aquaculture systems and increasing its resource volume requires further expansive production. However, a major factor preventing the establishment of aquaculture technology for this lobster is the difficulty with rearing processes from larval to juvenile production. A recent study shed light on the molecular mechanisms underlying larval development from the perspective of physiological functions of endocrine factors such as molting hormones. However, physiological studies of P. japonicus are still lacking. In decapod crustaceans, the X-organ/sinus gland complex is a well-known endocrine system that secretes the crustacean hyperglycemic hormone (CHH)-superfamily peptides that regulate growth, molting, sexual maturation, reproduction, and change in body color. In this study, we identified two CHHs from the sinus glands of P. japonicus using reversed-phase high-performance liquid chromatography in order to elucidate their physiological function for the first time.

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.

Population Growth Model and Mortality of Pakistan Lobster (Panulirus polyphagus) in Estuary Waters of Tarakan City

Lobster Panulirus polyphagus has a fairly high economic value and is found in the estuary waters of Tarakan City. This research aims to study the growth and mortality model of Lobster P. polyphagus originating in the estuary waters of Tarakan City. The research method was carried out using a quantitative descriptive method. Sampling was conducted 14 times from December 2021-May 2022 using gill nets. The results showed that the male sex ratio was more than the female. Allometric growth of males and females is negative allometric with a thin body shape. The structure of the size obtained was mostly in males ranging from 18.3-20.6 cm, and females around 20.5-22.2 cm. The maximum length growth of P. polyphagus based on von Bertalanffy's growth model was 31.519 cm in males and 31.374 cm in females. The total mortality (Z) of P. polyphagus for males and females was 1.104 and 1.119; catch mortality (F) of 0.106 and 0.253; natural mortality (M) of 0.998 and 0.866; exploitation rate (E) of 0.096 and 0.226, respectively. The high natural mortality causes the extinction of the Lobster species, so good management is needed so that it is sustainable.

Growth at molt of sub-adult scalloped spiny lobster Panulirus homarus reared in tanks

Grow-out of lobster performed in a tank culture system offers several advantages over floating sea cage culture, particularly in the control of environmental factors. However, the growth of lobster reared in tanks need to be evaluated to determine the rearing period of lobster to achieve market size. Growth in lobster is defined as the change in size through the molting process. Therefore, this study was performed to assess differences in weight and length increment at molt of male and female sub-adult scalloped spiny lobster Panulirus homarus, as well as to determine the annual weight increment of the lobster reared in tanks. Sub-adult lobsters with an initial average weight of 226.18±20.30 g were stocked in twenty 4000-L fiber tanks at 20 lobsters/tank. Each lobster was tagged by a photographic method of the carapace to enable the identification of individual molt, as well as growth increment. Observation of molt and growth of lobster was carried out for 42 days of rearing. Growth observation for 42 days showed that the length increment between male and female lobsters was significantly different. The average length increment of the male was significantly higher (10.00 mm) than those of the female (7.93 mm) (p<0.05). However, the weight increment was not different between the sexes. The average weight increment of males and females was 18.53 g and 20.71 g, respectively (p>0.05). In terms of the annual weight increment, both sexes also had fairly similar growth, achieving 168.38 g.yr-1, on average. This study found that there was increased growth, zero growth, and declined growth at molt in lobster P. homarus.

Cannibalism in cultured juvenile lobster Panulirus ornatus and contributing biological factors

Cannibalism is a major limitation to communally culturing the spiny lobster, Panulirus ornatus, and although frequently reported in research it is yet to be thoroughly investigated. To support continued innovation in culture, we must understand the contribution of cannibalism to juvenile mortality and identify influencing factors. This was accomplished through 900 h of time-lapse photography of three populations of juvenile lobsters over 30 d, including all ecdysis and cannibalism events to inspect individual weight, tank biomass, moult-stage, sex, and injury, as possible contributing factors. Total mortality was over 50% and attributed to the attack and cannibalism of moulting lobsters. Between 20 and 25% of moulting events in P. ornatus resulted in cannibalism of the moulting lobster. Population control and biomass stabilisation appear to be consequences of cannibalism, determined by fluctuations in tank biomass. Additionally, the moult stage of killer cannibals may suggest a nutritional benefit for lobsters in the latter half of the moult cycle. An increase in the average locomotor activity within a population during the hour before cannibalism occurs indicates that the factors driving cannibalism are present up to an hour before a moult. Here we demonstrate the flaws of previous assumptions related to the type and frequency of cannibalism in cultured P. ornatus systems and highlight contributing factors which warrant further study. Building from this research we may identify drivers of cannibalism among juvenile P. ornatus, with the aim of mitigating this behaviour in research and industry culture.

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.

Effect of different diets on growth performance, physiological response and behavior of spiny lobster Panulirus homarus (Linnaeus, 1758)

This study aimed to know the effect of different feedings on growth performance, physiological responses, and behavioral changes of juvenile spiny lobsters. The experimental method used a completely randomized design with three treatments and four replications. There were three different feeds used as treatment, namely: flesh mussel (K), commercial fish feed (I), and commercial shrimp feed (U). Feed is given as much as 30% of body weight, five times per day at 6:30 am, 12:00 pm, 4:00 pm, 9:00 pm, and 2:00 am. The results showed that the commercial feeding of fish (I) significantly (P&lt;0.05) increased the survival rate and biomass of spiny lobster for 54.17% and 141.7 g, respectively. While fresh mussel give better growth and stress response, but had the lowest survival rate. The results of the physiological response test of lobster were more effective in suppressing lobster stress levels than other treatments (P&lt;0.05). The behavior of juvenile spiny lobsters showed a very striking color difference and reflex impairment scores, which indicated that the vitality of the treated juveniles (I) was better than the vitality of the treatments (K) and treatment (U). This study shows that commercial fish feed (I) is recommended for maintaining spiny lobsters in the juvenile phase, although it needs further maintenance by using an appropriate feed formulation to improve the growth performance of spiny lobsters.

Variation in body size drives spatial and temporal variation in lobster-urchin interaction strength.

How strongly predators and prey interact is both notoriously context dependent and difficult to measure. Yet across taxa, interaction strength is strongly related to predator size, prey size and prey density, suggesting that general cross-taxonomic relationships could be used to predict how strongly individual species interact. Here, we ask how accurately do general size-scaling relationships predict variation in interaction strength between specific species that vary in size and density across space and time? To address this question, we quantified the size and density dependence of the functional response of the California spiny lobster Panulirus interruptus, foraging on a key ecosystem engineer, the purple sea urchin Strongylocentrotus purpuratus, in experimental mesocosms. Based on these results, we then estimated variation in lobster-urchin interaction strength across five sites and 9 years of observational data. Finally, we compared our experimental estimates to predictions based on general size-scaling relationships from the literature. Our results reveal that predator and prey body size has the greatest effect on interaction strength when prey abundance is high. Due to consistently high urchin densities in the field, our simulations suggest that body size-relative to density-accounted for up to 87% of the spatio-temporal variation in interaction strength. However, general size-scaling relationships failed to predict the magnitude of interactions between lobster and urchin; even the best prediction from the literature was, on average, an order of magnitude (+18.7×) different than our experimental predictions. Harvest and climate change are driving reductions in the average body size of many marine species. Anticipating how reductions in body size will alter species interactions is critical to managing marine systems in an ecosystem context. Our results highlight the extent to which differences in size-frequency distributions can drive dramatic variation in the strength of interactions across narrow spatial and temporal scales. Furthermore, our work suggests that species-specific estimates for the scaling of interaction strength with body size, rather than general size-scaling relationships, are necessary to quantitatively predict how reductions in body size will alter interaction strengths.