Palinurus Elephas Research Articles

Settlement and juvenile habitat of the European spiny lobster <i>Palinurus elephas</i> (Crustacea: Decapoda: Palinuridae) in the western Mediterranean Sea

Settlement characteristics, like timing, depth, microhabitat and density of European spiny lobster Palinurus elephas are described for the very first time. Regular SCUBA-diving surveys were conducted from July 1998 to January 2000 on rocky bottoms of three different geologic origins to assess substratum-dependent differences in recruitment density. Settlement of pueruli took place in June-July, a few weeks after sea surface temperature started to rise. The highest density of juveniles was found at 10-15 m depth. Most spiny lobsters settled in limestone rocks, into empty holes of the date mussel Lithophaga lithophaga, which provided daytime refuge. As they grew, individuals were increasingly found in larger holes and crevices of the rock surface. Sizes were estimated from photographs taken at night when the animals were actively foraging. The smallest observed individuals measured 7.5-8 mm carapace length (CL), but they reached 15-18 mm CL at the end of October. The consequences of our results for the management of the spiny lobster populations in the northwestern Mediterranean are summarily discussed.

Diet of the spiny lobster Palinurus elephas (Decapoda: Palinuridea) from the Columbretes Islands Marine Reserve (north-western Mediterranean)

Stomach contents of 382 Palinurus elephas collected in the Columbretes Islands Marine Reserve (north-western Mediterranean) were examined to study the diet and to assess ontogenetic and sex related differences in feeding regime. Molluscs, crustaceans, and sea urchins were the most common prey. Diet composition varied with lobster size but not with sex. Ontogenetic changes in diet were reflected in the progressive reduction of the contribution of gastropods and crustaceans and in the increased importance of other prey such as fish.

Dynamics of a protected Western Mediterranean population of the European spiny lobster Palinurus elephas (Fabricius, 1787) assessed by trap surveys

A protected population of the spiny lobster, Palinurus elephas, was studied eight years after establishment of the Columbretes Islands Marine Reserve (western Mediterranean). Experimental trap fishing in the reserve and at two unprotected sites revealed that cessation of fishing in the reserve is probably responsible for high catch rates observed there and that the annual fishing closure is effective in rebuilding populations in exploited areas. In the reserve, variations in abundance, sex ratio, and size of lobsters were conspicuous. Catch rates were always higher in deep (50–80 m) than in shallow areas (20–50 m). Bathymetric differences in abundance were smallest in early summer, possibly because of seasonal onshore movements associated with reproduction. Females were always more abundant than males and less variable in number and size. Ancillary data suggest that reproductive and moulting behaviour, particularly of males, influences population estimates of P. elephas from trap surveys. Presence of subadults in deeper waters of the reserve suggests that 2- to 3-year-old juveniles undergo ontogenetic migration from the shallow settlement habitats (<20 m) to deeper habitats (>50 m). The results highlight the effectiveness of fishing restrictions in rebuilding P. elephas populations and suggest that the lobster population in the reserve is not closed.

Larval culture of the European spiny lobster Palinurus elephas

The development of phyllosomas of the European spiny lobsterPalinurus elephas was examined in recirculating culture systems. Approximately 2000 newly hatched phyllosomas were introduced into each of three 100-L circular culture containers. Two of the containers, A and B, shared a filter; container C had a separate system of similar design. Hatched larvae of the sailfin sandfish Arctoscopus japonicus were fed to phyllosomas in container A, and pieces of the gonad of the mussel Mytilus edulis to those in container B. Phyllosomas in container C received both foods for the first 24 days; thereafter A. japonicus comprised their sole diet. Water temperature was maintained at 19–20˚C in containers A and B and at 16–18˚C in container C. Two individuals from container A and 10 from container C metamorphosed into pueruli after six instars at 65 and 69 days respectively, whereas earlier trials involved an estimated nine instars to metamorphosis after 132 days. Larvae thus cultivated were used to describe, for the first time, the morphological development of Palinurus elephas phyllosomas through metamorphosis to the puerulus stage. Fish larvae, such as A. japonicus may be an important dietary component for cultivation of palinurid phyllosomas.

Gill Na,K-ATPase in the spiny lobster Palinurus elephas and other marine osmoconformers. Adaptiveness of enzymes from osmoconformity to hyperregulation.

Haemolymph inorganic osmolyte changes and Na,K-ATPase activities in trichobranchiate and epipodite tissues were examined in the spiny lobster Palinurus elephas gradually acclimated from seawater (SW; 38 ppt, salinity; 1291 mOsmol/l) down to dilute seawater (DSW; 20 ppt, salinity; 679 mOsmol/l). During acclimation to DSW haemolymph was only transiently hypoosmotic, becoming isosmotic to the medium over a 24-h period of acclimation. Na,K-ATPase specific activities in homogenates of the trichobranchiate gills from SW- and DSW-acclimated spiny lobsters were in the range of 2-3 µmol Pi/h/mg protein and were not significantly different. It has also been confirmed for the marine stenohaline crustaceans Maja crispata and Dromia personata that gill Na,K-ATPase maintains the same level of specific activity in SW- and DSW-acclimated crabs. The saponin-treated fraction of Na,K-ATPase activity in trichobranchiate gills was 67-89% and epipodites 63-64% over the native homogenates' activity and no differences in enzyme activities upon saponin treatment between SW- and DSW-acclimated spiny lobsters were found. Recovery of 6% and enrichment factor (1.6) of Na,K-ATPase in partially purified plasma membrane fractions of epipodites was relatively low and not different in SW- and DSW-acclimated spiny lobsters. In the hemiepipodite, negative short-circuit current was in the range from -16.7 to -22.7 µA cm(-2) and conductance varied in the range of 205-290 mS cm(-2), values which were not significantly different in spiny lobsters residing in SW or DSW. Very high conductance suggests leakiness of the hemiepipodite epithelium-cuticular complex. In contrast to the group of euryhaline hyperosmoregulating Crustacea in which activation of the specific activity of Na,K-ATPase upon acclimation to dilute seawater occurs, in marine osmoconformers there is no activation of the enzyme in dilute seawater. Based on the literature data and our own results, we have reported a correlation coefficient of 0.65 between specific activity of Na,K-ATPase and the sodium gradient (mmol Na/l; haemolymph-seawater ) between 12 species of osmoconforming and osmoregulating Crustacea. During evolution, hyperosmoregulating Crustacea have achieved internal osmolyte gradients generated by Na,K-ATPase and lowering the gill surface permeability. However these adaptive characteristics are not present in marine osmoconforming Crustacea, restraining them to migrate in the brackish water habitats.

Application of ecosystem culture method for complete development of phyllosomas of spiny lobster

The complete larval development of the phyllosoma stages has been achieved for the following palinurids: Jasus lalandii, J. edwardsii, and J. verreauxi, cool temperate species from the southern hemisphere; Palinurus elephas, a cool temperate species from Europe, and Panulirus japonicus, a warm temperate species from Japan. Males and females from the wild were transported to Sanriku, Japan, where they were bred in captivity for several successive years. Hatching occurred once each year between spring and summer. Newly-hatched phyllosomas were cultured in a 15, 20, 30 or 100 1 container which incorporated an upwelling system. The larval culture container was connected to a 200 or 500 1 microalgae Nannochloropsis spp. culture tank, and water recirculated between the two. For the early phyllosomas, food consisted of Artemia nauplii in combination with pieces of mussel ( Mytilus edulis) gonad. Mussel gonad was used exclusively after the 2nd or 3rd instar. The highest larval survivals (about 10%) were found with J. verreauxi while the lowest were for P. elephas, where heavy mortalities were noted at the 1st instar. Nevertheless, P. elephas is considered to be the most promising aquaculture species because its phyllosoma life of 132 days is short compared to 200–300 days for the other species.

Sensory-induced plasticity of motor pattern selection in the lobster stomatogastric nervous system.

In a previous study, a bilateral sensory input pathway to the crustacean stomatogastric nervous system was reported to induce the functional switching of an identified motor neuron (VD) from one rhythm generating neural network (the pyloric circuit) to another (the cardiac sac network). In the present in vitro study on the spiny lobster, Palinurus vulgaris, we have shown that under certain conditions, repetitive trains of phasic stimulation (1 s, 40 Hz) of one of these sensory nerves elicits either an increase or a decrease in efficacy of the VD switching response. In preparations showing no previous sign either of increase or decrease in VD switching, either response can be induced by prior conditioning stimulation. The increasing effect can be induced by unpaired conditioning stimulation of the contralateral sensory nerve. Conversely, the decrease in switching efficacy is obtained by pairing stimulation of the sensory-motor pathway with that applied to its contralateral partner. Both the experimentally induced increase and decrease in VD switching are long-lasting, remaining observable for at least 20 min and in some cases up to 3 h after the original conditioning procedure. Our results suggest that this system provides a suitable 'simple' model for the analysis of experience-related plasticity of the switching of a neuron from one network to another.

Dimerization of an antigenic peptide leads to strong interaction with its antibody

A sequential epitope reacting with a monoclonal antibody against Panulirus interruptus hemocyanin was localized in the C-terminal CNBr peptide. As the antibody reacted with about equal affinity with different subunits of this and with hemocyanin from another spiny lobster, Palinurus vulgaris, the epitope was assigned to a conserved sequence region. The CNBr peptide, which was linked to another peptide via a disulfide bridge, was reduced and reoxidized. As a result, not the heterodimer but only the two disulfide-linked homodimers were formed. The dimeric C-terminal peptide had a much higher affinity for the monoclonal antibody than the monomeric peptide. This may be explained by the presence of two independent mobile interaction sites in each of the two reacting molecules.

Recent studies on the crawfish Palinurus elephas in South Wales and Cornwall

From May 1993 until January 1994, 788 male and 1604 female crawfish, Palinurus elephas in total, were examined from the South Wales and Cornish fisheries. Mean carapace length (CL) of Cornish crawfish was 125.6 mm for males, 132.4 mm for females and 135.0 mm for berried females, while mean CL for Welsh crawfish was 155.8 mm for males, 138.7 mm for females and 138.6 mm for berried females. The overall size distribution of male Welsh crawfish differed significantly from that observed in the Cornish population. An analysis of variance gave significant (P<0.05) differences for the factors; Site, Sex and the Sex/Site and Month/Sex interactions. Male crawfish reached greater overall size than female crawfish, but for specimens of equal CL, total lengths (TL) of females were longer than those of males. Males were heavier than females of equal CL or TL.

Primary structure of hemocyanin from Palinurus vulgaris

The primary structure of hemocyanin from the spiny lobster Palinurus vulgaris was determined using a mixture of at least four slightly different subunits. Heterogeneities were observed in 32 (5%) of the positions. The amino acid sequence differs at about 20% of the positions from that of subunit a of Panulirus interruptus hemocyanin.

Culture of Phyllosomas of Spiny Lobster and Its Application To Studies of Larval Recruitment and Aquaculture

Complete larval development of spiny lobsters in culture has been achieved for cool temperate species, Jasus lalandii (H. Milne Edwards, 1837), Jasus novaehollandiae Holthuis, 1963, Jasus edwardsii (Hutton, 1875), Jasus verreauxi (H. Milne Edwards, 1851) and Palinurus elephas (Fabricius, 1787), and a warm temperate species, Panulirus japonicus (Von Siebold, 1824) since 1987. A good survival rate of about 10% was obtained for J. verreauxi. The factors important to the successful larval culture were: (1) introduction of microalgae into the culture water, (2) feeding with mussels and (3) supply of water from the bottom of the culture tank to induce a continuous circular current in the tank. The shortest duration of the phyllosoma stage for the above species, respectively, was 306, 319, 212, 197, 132, and 307 days. The number of instars was 17 for Jasus spp., 9 (estimated) for P. elephas and 25 (estimated) for P. japonicus. The shortest duration of the pucrulus stage was 19, 12, and 11 days for the above animals, respectively. Jasus verreauxi may be suitable because of its potential for a high survival rate. Palinurus elephas is also an interesting possibility because of its short larval life. Duration of the larval stage seems to be species specific. Within a species, it is affected by water temperature and food availability for the phyllosoma but exclusively by water temperature for the puerulus.

TAG RETENTION IN THE MEDITERRANEAN SLIPPER LOBSTER

ABSTRACT Mediterranean slipper lobsters, Scyllarides latus, were tagged using 3 types of ‘spaghetti’ tags. Each lobster was tagged at 2 points on its dorsal surface: between the carapace and the abdomen and between the third and fourth abdominal segments. The survival, molting, and tag retention of these lobsters was monitored for 16 months. Overall tag retention was significantly higher among lobsters tagged with anchor tags that had conical tips compared to those tagged with regular anchor tags. 86.7% of lobsters tagged with conical-tipped tags molted and only 20% died, while of the lobsters tagged with regular tags only 33.3% molted and 40% died. After molting, lobsters in both groups tended to keep more tags in the posterior position than in the anterior position.

Sexual maturity, reproductive season and fecundity of the spiny lobster Panulirus penicillatus from the Gulf of Eilat (Aqaba), Red Sea

Panulirus penicillatus Olivier (1791) (Decapoda: Palinuridae) is widely distributed in the Indian and Pacific Oceans and is the most common spiny lobster in the Red Sea. Female lobsters (n =234), were collected on four occasions in 1986 from the coral reef of Dahab, 110 km south of Eilat, Israel. Field data and the gonadal index indicated that the reproductive season was from February to October, during which the females spawned 2-4 times. In nature, females became sexually mature at a carapace length (CL) of 50 mm. This result was confirmed by morphometric analysis of the regression between pleopodal exopodite length and carapace length. The number of eggs per spawn (E) was related to CL by the equation E=2.715 ×(CL)2.581. The incubation period of eggs was 35.5�1.0 days (�s.d.) at temperatures of 24-27�C in the aquarium. The results are compared with data on P. penicillatus from other parts of its geographic range, and the effect of geographic isolation on reproduction is discussed.

Cholinesterases from Maia verrucosa and Palinurus vulgaris: A comparative study

1. Soluble cholinesterases were purified from the crustaceans Maia verrucosa and Palinurus vulgaris, belonging to the same order (Decapoda) and suborder (Reptantia). 2. Purification was carried out from 100,000 g supernatants by affinity chromatography on a procainamide-containing gel. 3. Each purified enzyme is a single protein giving differently sized subunits on PAGE-SDS electrophoresis. 4. According to k cat/ K m values, the enzymes are propionylcholinesterase ( M. verrucosa) and butyryl-cholinesterase ( P. vulgaris), even if acetylthiocholine and propionylthiocholine respectively display the highest rates of hydrolysis. 5. According to kinetic constants, the enzyme from M. verrucosa mainly discriminates among substrates (choline or p-nitrophenol esters) on the basis of steric hindrance and hydrophobic interactions. Catalytic efficiency of the enzyme from P. vulgaris is mostly affected by electrostatic forces. Charge-bearing substrates are quite better for both the cholinesterases. 6. Kinetic properties of the studied enzymes are compared with those of other Invertebrata and their possible phylogenetic and adaptive features are discussed.

Population structure and growth in captivity of the spiny lobsterPanulirus penicillatus from Dahab, Gulf of Aqaba, Red Sea

Panulirus penicillatus (Olivier, 1791) (Decapoda: Palinuridae) is the most common spiny lobster in the Red Sea and is widely distributed in the Indian and Pacific Oceans. Lobsters (n=377) were collected on four occasions during 1986 on the coral reef at Dahab, Sinai, Egypt. Average size of the collected individuals was 70.5±24.6 mm carapace length (CL) for males and 63.2±15.9 mm CL for females. The sex ratio was 1:1.64 males to females. Length increment per molt was inversely correlated with size and ranged from 2.1 mm per molt in the 40 to 50 mm CL size class to less than 1 mm in the 60 to 70 mm CL size class. Average intermolt period was ca. 136 d for all size classes. The relationship between carapace length and body weight was expressed by the equation:Wb=6.43 × 10−4 × (CL)2.89.P. penicillatus from Dahab differ in size, sex ratio and growth rate compared to other palinurid populations throughout their range. This might represent the effect of isolation and location at the edge of the geographical range for this species. It may also indicate an adaptation to their unique habitat in the coral reef in comparison to other palinurid species.

Lobster haemocyanin. Influence of acclimatization on subunit composition and functional properties

Haemocyanin from the lobster Palinurus elephas has been shown to change in its subunit composition according to the time of year. In contrast, in Palinurus mauritanicus, a lobster living at greater depth, no seasonal changes in subunit composition have been observed. The results obtained from a set of experiments performed on some Palinurus mauritanicus acclimatized in an aquarium have clearly indicated that modifications of haemocyanin subunit composition may be involved in the adaptation of arthropods to environmental change.

Lack of correspondence between histochemical and structural fiber typing in antennal muscles of the rock lobster Palinurus vulgaris

1. 1. Sarcomere lengths and fine structure were examined in three histochemical fiber types of antennal muscles of the rock lobster. 2. 2. Sarcomere lengths are distributed over a continuum of values from 6.5 to 19 μm. 3. 3. Although a correlation between ATPase activity and sarcomere length is demonstrated, fibers with high ATPase activity do not have the sarcomere length typical of fast contracting fibers. 4. 4. These fibers deviated from the typical fast structure in having long sarcomeres (> 6.5 μm) and in having some unusual ultrastructural characteristics (absence of the H-band, presence of Z-tubules, high thin to thick ratio, 5:1) associated with other more classical features. 5. 5. This finding demonstrates that sarcomere length measurements do not always accurately predict the physiological performance of a single muscle fiber. 6. 6. The fiber type composition of two antagonistic antennal muscles is compared and the functional significance of the results is discussed with respect to their role in behavior.

Differential scanning calorimetry of lobster haemocyanin

Differential scanning calorimetry has been performed with Palinurus vulgaris haemocyanin monomers and hexamers. The denaturation of the protein is irreversible. Both the temperature of the transition maximum and the enthalpy are lower for the monomer than for the hexamer. A scan rate dependence of the temperature of the maxima is found for both the monomer and the hexamer; for the hexamer at least, this can be explained in terms of a two-state kinetic model. Some comments are made as to the use of equilibrium thermodynamics in the analysis of irreversible scanning calorimetric traces.

Partial amino acid sequence of a hemocyanin subunit from Palinurus vulgaris

1. 1. Hemocyanin from the spiny lobster Palinurus vulgaris was separated into two fractions, which were designated as subunits a and b. 2. 2. 55% of the amino acid sequence of subunit b has been determined. A comparison with Panulirus interruptus hemocyanins shows 78% sequence identity with subunit a and 56% with subunit c. It has carbohydrate attached to domain. Two half-cystines have been substituted, indicating that it probably possesses only one disulfide bridge. Heterogeneity has been observed in seven out of 380 positions determined so far. 3. 3. Subunit a is almost identical with subunit b. In contrast to Panulirus interruptus and Panulirus japonicus, Palinurus vulgaris hemocyanin contains no c-type subunit. 4. 4. A position in the tentative evolutionary tree of arthropod hemocyanins based on sequence differences has been assigned to Palinurus vulgaris subunit b.

Control by an identified modulatory neuron of the sequential expression of plateau properties of, and synaptic inputs to, a neuron in a central pattern generator

Recordings from the lateral gastric (LG) neuron, which forms part of the gastric mill central pattern generator in the red lobster, Palinurus vulgaris, indicate that regenerative membrane properties (plateau properties) and synaptic inputs interact sequentially rather than simultaneously to determine its discharge pattern. LG thus presents a composite discharge, consisting of 2 separate segments of firing and one silent period. The first firing segment depends on regenerative membrane properties; this is the endogenous component, or segment, of LG's discharge. The second firing segment is the result of extrinsic synaptic input, forming the synaptic component of LG's discharge. The relative importance of these 2 components can vary, and thus LG's discharge ranges from one in which LG fires only as a result of its endogenous component to one in which its endogenous component is entirely absent and only the synaptic component underlies action potentials. Activity in an identified modulatory neuron suppresses the endogenous segment and enhances the synaptic segment of LG's discharge. This long-lasting effect in turn changes phase relationships within the gastric mill network and provides mechanisms for producing flexibility in the gastric pattern generator and for ensuring that a specific motor output is generated by a flexible neural network.