Late-stage Phyllosoma Research Articles

Amended larval recruitment model for the Japanese spiny lobster Panulirus japonicus based on new larval records and population genetic data in Taiwan

The spiny lobster Panulirus japonicus (von Siebold, 1824) has a rather restricted distribution in the northwestern Pacific, ranging from Japan to Taiwan and southeastern China. It has been hypothesized that the Japanese populations of this species share a common pool of larvae for recruitment, and that these larvae are transported by the Kuroshio Subgyre. However, it remains unclear how the populations around western Taiwan and southeastern mainland China are maintained, as they are outside the Kuroshio Subgyre. In this work, a final-stage phyllosoma and a puerulus of this species were discovered for the first time in Taiwanese waters and off the southern coast. An extended genetic analysis of the Taiwanese and southeastern Chinese populations of P. japonicus showed that they all share a common gene pool. The larval recruitment hypothesis for P. japonicus was therefore modified by suggesting that its late-stage phyllosoma or puerulus may reach further south to southern Taiwan, with the branch of Kuroshio Current accounting for the larval recruitment of the populations around western Taiwan and southeastern China.

Effect of water temperature on the development and energetics of early, mid and late-stage phyllosoma larvae of spiny lobster Sagmariasus verreauxi

The effect of water temperature on the survival, growth, respiration, apparent feed intake and activity of Sagmariasus verreauxi phyllosoma during early, mid and late larval development through metamorphosis was examined. Early-stage phyllosoma were cultured from hatch to instar 4 at temperatures 17, 20, 23, 26 and 29°C for between 18 and 44days. Survival and rate of development were greatest at 26°C, while all animals died at 29°C. The optimum temperature for larval growth in weight was 23°C. Optimum metabolic feeding efficiency measured as the maximum convection requirement index, (CRI, quotient of feed intake and oxygen consumption) was from 23 to 26°C. Reduced growth at 26 compared to 23°C was likely due to accelerated development, resulting in a disequilibrium between moult increment and energy storage rates, whereas, lower metabolic feeding efficiency at 17–20°C may be attributed to increased energetic expenditure associated with activity. Mid-stage phyllosoma were cultured from instar 8 to instars 10–11 over 69days at 19, 21, 23, 25, and 27°C. Survival was reduced at 27°C. The optimum temperature for growth, development and CRI was 23°C. Late-stage phyllosoma were cultured from instar 13 over 112days, or until metamorphosis, at 21, 23 and 25°C. There was no significant difference in survival among temperatures. The rate of development was fastest at 23°C with 36% of phyllosoma metamorphosing to puerulus, compared to 20% at 21°C and 28% at 25°C. Mass of final instar phyllosoma and puerulus were greatest at 21°C, demonstrating a downward shift in the optimum temperature for late-stage phyllosoma. The shift in temperature optimum for late-stage larvae involves changes in feeding and energy metabolism. The study demonstrates that the physiological energetics of S. verreauxi changes with larval ontogenetic development, which is an important consideration for optimizing spiny lobster propagation success.

Molecular Diet Analysis of Phyllosoma Larvae of the Japanese Spiny Lobster Panulirus japonicus (Decapoda: Crustacea)

To clarify the natural diet of phyllosoma larvae of the Japanese spiny lobster Panulirus japonicus, the sources of 18S rDNA clones obtained from the hepatopancreas were investigated. Of a total of 1537 clones examined, 160 had different restriction profiles from the host larvae, in which 21 restriction types were observed. Nucleotide sequences of 16 of 21 restriction types were successfully determined and their assignments were investigated by homology search and phylogenetic analysis. From seven late-stage larvae collected in spring to early summer, eukaryote DNA molecules of Teleostei, Oomycetes, Mycetozoa, and Fungi were identified. Exogenous DNA from four younger phyllosoma larvae collected in late autumn could not be recovered. A previous study identified DNAs of cnidarians and urochordates in late-stage phyllosoma larvae of a closely related species collected in winter. This indicates that the phyllosoma larvae are opportunistic carnivores, whose diets correlate with the relative abundance of prey organisms in the ambient water.

A late-stage phyllosoma larva of the spiny lobster Panulirus echinatus Smith, 1869 (Crustacea: Palinuridae) identified by DNA analysis

A late-stage phyllosoma larva of the genus Panulirus was caught in the central Atlantic in October 2000. Nucleotide sequence analysis of mitochondrial 16S rDNA identified this larva as Panulirus echinatus, which has been undescribed to date. Morphological examination indicated that this eighth stage larva belonged to phyllosoma species group 2, distinguishable from the other Atlantic species of the genus but closely related to an Indo -Pacific species, P. penicillatus, which is in accordance with the results of a molecular phylogenetic analysis.

Molecular attempt to identify prey organisms of lobster phyllosoma larvae

A molecular approach was adopted to investigate the natural diets of palinurid and scyllarid lobster phyllosoma larvae. The central domain of the 18S rDNA gene was amplified using nested polymerase chain reaction (PCR) and genomic DNA extracted from the larval hepatopancreas. The resulting 18S rDNA clones were screened using restriction fragment length polymorphism (RFLP) analysis, and then FASTA homology search and phylogenetic analysis were performed on the nucleotide sequences to identify the source of the eukaryotic organisms. The feasibility of this method was confirmed using the laboratory-reared phyllosoma larvae of the Japanese spiny lobster Panulirus jap onicus that were fed either with common mussel Mytilus edulis gonads or with Artemia nauplii exclusively. Among the 804 clones isolated from five wild-caught mid-to late-stage phyllosoma larvae (three palinurids and two scyllarids), 0–132 clones per sample possessed restriction profiles distinct from those of the hosts. The Cnidaria and Urochordata DNA were identified from both the palinurid and the scyllarid larvae, which were thought to be prey animals for the mid- to late-stage phyllosoma larvae.

Molecular Species Identification of Spiny Lobster Phyllosoma Larvae of the Genus Panulirus from the Northwestern Pacific

To identify lobster phyllosoma larvae of the genus Panulirus occurring in waters adjacent to Japan, genetic variation within and between 10 Indo-Pacific lobster species was investigated using restriction fragment length polymorphism (RFLP) analysis for the 1300-base pair mitochondrial cytochrome oxidase I (COI) gene. RFLP analysis using two endonucleases (AluI and TaqI) enabled discrimination of all species, including the P. longipes complex. The diagnostic DNA markers, supplemented with nucleotide sequence analysis, were applied to 44 mid- to late-stage phyllosoma larvae (7.4 to 27.7 mm in body length) collected in the northwestern Pacific. These samples were unexpectedly variable in species composition, comprising P. japonicus (n = 16), P. longipesbispinosus (21), P. longipes longipes (1), P. “aka” (1), and P. penicillatus (5). Comparison of larval size at similar stages revealed that P. l.bispinosus larvae were significantly larger than P. japonicus.

Rock lobster Jasus edwardsii larval retention by the Wairarapa Eddy off New Zealand

In February 1998, Jasus edwardsii larval catches off the east coast of New Zealand were binomial in size and stage of development. Mid-stage larvae (presumed to be from the 1997 cohort) appeared to be contained within a large permanent eddy found offshore, known as the Wairarapa Eddy. Late-stage larvae (1996 cohort) have a different distribution from the mid-stage larvae, being found closer inshore of the eddy. Pueruli (also 1996 cohort) were found well inshore of the eddy. Surface currents derived from TOPEX/Poseidon altimeter measurements of sea level are used to simulate larval concentrations. The numerical simulations show that the different distributions of the 3 groups cannot be explained on the basis of advection alone. Mid-stage concentrations appear to be well described by passive drift alone, but the simulations suggest some mechanism inducing shoreward transport is needed for both pueruli and late-stage phyllosomas. Observed puerulus concentrations are best matched by adding a shorewards-directed speed of 8 to 10 cm s -1 for between 1 and 3 wk before the date of the cruise. Late-stage phyllosoma concentrations are best matched by adding speeds of 4 to 6 cm s -1 . Sustained shorewards swimming speeds of 8 to 10 cm s -1 are well within the estimates of swimming speed that have been reported elsewhere for pueruli. To our knowledge, extended directed horizontal swimming has not been reported for phyllosomas, yet in the final stage, the pleopods are almost as well developed as they are in the pueruli. These final stage larvae could well use forward pleopod propulsion, in conjunction with exopodal setai beating, to allow them to swim.

Jasus Edwardsii Larval Recruitment Off the East Coast of New Zealand

Geographic differences in levels of Jasus edwardsii puerulus settlement on the east coast of New Zealand during the 1980's were associated with differences in abundance offshore of mid- and late-stage phyllosoma larvae and with water flow patterns. Levels of puerulus settlement on crevice collectors and abundance of phyllosomas in plankton samples were greatest off the North Island south of about East Cape. The pattern of phyllosoma abundance appeared to be determined by factors which included levels of local larval production and the oceanography. Phyllosomas occurred almost exclusively seaward of the continental slope while most pueruli were caught on the shelf. Some phyllosomas reached final stage about 12 months after the spring hatching, but often metamorphosis to the puerulus stage and settlement did not take place until the following summer to spring; this gives an oceanic development period of 12-24 months. Settlement seasons have been generally consistent over time scales of 1-3 decades. Most commonly, settlement is in winter, but the main settlement seasons vary according to locality, nearby sites having similar seasons except over particular stretches of coastline where seasons change radically. Reasons for the seasonal pattern in settlement are unknown. Year to year levels of settlement were correlated at widespread sites, showing that factors which drive larval recruitment may influence large areas in a similar way at the time.

COMPARATIVE MORPHOLOGY OF THE MOUTHPARTS AND FOREGUT OF THE FINAL-STAGE PHYLLOSOMA, PUERULUS, AND POSTPUERULUS OF THE ROCK LOBSTER JASUS EDWARDSII (DECAPODA: PALINURIDAE)

ABSTRACT The gross morphology and fine structure of the mouthparts and foregut of the rock lobster Jasus edwardsii were studied in its late larval and early juvenile stages. The stage-XI phyllosoma has third maxillipeds with specialized setae, second maxillipeds and first maxillae with strong setae, mandibles with well-developed molar and canine-like processes and teeth, and a foregut with well-developed grooves and brushes but no gastric teeth. The first-molt juvenile has third and second maxillipeds and first maxillae with rows or tufts of numerous strong setae, wellcalcified mandibles with strong molar and incisor processes, and a foregut with well-developed ossicles, grooves, brushes, and strong gastric teeth. In contrast, the puerulus has maxillipeds and maxillae with only small numbers of setae, uncalcified mandibles with a rudimentary incisor, and a foregut with a small number of ossicles and setae, and rudimentary lateral teeth. These observations suggest that the late-stage phyllosoma of J. edwardsii feeds primarily on large, soft materials and the early postpuerulus on hard, as well as soft, materials. In contrast, the puerulus probably does not feed during some or all of its existence, and any feeding is on small, soft materials. Use of nutrients stored in the digestive gland is one possible way that the puerulus could meet its energy requirements.

Identification of late-stage phyllosoma larvae of the scyllarid and palinurid lobsters in the Japanese waters.

Based on zooplankton samples collected in the Kumano-and Enshu-nada seas north of the Kuroshio Current, phyllosoma larvae were examined, with the result that those of eleven species, belonging to five genera Ibacus, Parribacus, Scyllarides and Scyllarus (Scyllaridae) and Panulirus (Palinuridae), are identified. Among these larvae, five species of Scyllarus and two species of Panutirus are described herein. Further, keys to the genus and species of late stages of scyllarid and palinurid phyllosoma larvae in the Japanese waters are represented.

Distribution and Dispersal of the Phyllosoma Larvae of the Western rock Lobster, Panulirus cygnus, in the South-eastern Indian Ocean

Data on the phyllosoma larvae of P. cygnus caught on seven cruises carried out between April 1976 and January 1977 off the west coast of Australia are presented and discussed. The studies were undertaken to determine the length of the plankton cycle, the distribution of the phyllosoma in the south-eastern Indian Ocean and the extent of the offshore dispersal. Analyses showed the average length of the planktonic life to be less than one year and probably between 9 and 11 months. After hatching most early phyllosoma were transported offshore. Few larvae remained on or near the continental shelf. The maximum westward extent of the phyllosoma distribution of P. cygnus was not determined because significant numbers of phyllosoma were still found as far offshore as 99� 001E. (1500 km offshore), the furthest station sampled. The phyllosoma were distributed over an extensive area of the south-eastern Indian Ocean, and there were few stations beyond the continental shelf between 24� 30'S. and 35� 00'S., from 99� 00'E. to 115� 00'E., during midwinter, at which phyllosoma were not caught. The highest densities of mid-and late-stage phyllosoma occurred between 111� 00' E. and 104� 00' E. (between 375 and 1030 km offshore), at 29� 30'S. The area of greatest abundance was due west of the approximate centre of the adult distribution on the coast. The significance of the circulation of the south-eastern Indian Ocean in the transport of the larvae is discussed.

Ecological investigations of the late-stage phyllosoma and puerulus larvae of the western rock lobster Panulirus longipes cygnus

The distribution and abundance of the late-stage phyllosoma larvae of Panulirus longipes cygnus George and the distribution and densities of the final larval stage, the puerulus, both in the plankton and at settlement along the coast, were investigated. A total of 3,617 late-stage phyllosoma (Stages VI to IX) and 301 puerulus larvae were caught at 187 plankton stations during the July to November periods 1974, 1975 and 1976 off the west coast of Australia between 29°00′ to 32°30′S and 113°30′ to 115°00′E. The depth range sampled was 0 to 35 m on the continental shelf and 0 to 90 m off the shelf. During onshore/offshore cruises with similar sampling effort on and off the shelf, 1,169 late-stage phyllosoma larvae were taken, of which only 9 were caught on the shelf, and these near the outer edge. A series of cruises sampling two areas beyond the shelf near 29°30′ and 32°00′S yielded 2448 late-stage phyllosoma, with greater densities of larvae in the northern location. The settlement of puerulus-stage larvae along the coast in the same geographical range was also greater in the north than in the south. The data from the onshore/offshore cruises showed a definite effect of moon phase on numbers of puerulus larvae caught on the shelf, with higher catches near new moon. The low numbers of puerulus larvae (usually 0, 1 or 2 individuals) caught at all stations showed that the puerulus stage is sparsely distributed in the plankton. Fewer puerulus larvae were present at the surface than at lower depths, but it was not possible to determine a depth preference for the puerulus between 10 m and the lowest depths sampled because of the low catch numbers. No relationships were found between puerulus larvae density and surface-water temperature, salinity, or plankton biomass at each station. Data on the larval distributions indicate that, near the end of their planktonic existence, the majority of the late-stage phyllosoma larvae of P. longipes cygnus are not carried onto the shelf, where mixing of oceanic and continental shelf waters occurs only on the outer third, but are transported southward by oceanic circulation beyond the shelf. The puerulus moults from the last phyllosoma stage beyond the shelf and completes the larval cycle by swimming across the shelf and settling in the shallow reef areas.

Factors affecting the distribution of rock-lobster larvae (Panulirus longipes cygnus), with reference to variability of plankton-net catches

One of the major problems in the quantitative study of the distribution of larvae of the western rock lobster Panulirus longipes cygnusGeorge, is the high variability in planktonnet catches taken at night, even when replicate hauls are made at a single station. Some of the possible causes of this variability are considered. The density of early and late-stage phyllosoma larvae caught at the surface at night showed no direct relationship to either temperature or salinity. Early-stage phyllosoma larvae were equally well represented at the surface under all light conditions encountered at night. In contrast, the density of late-stage phyllosoma larvae at the surface was, on an average, four times greater on dark nights than on bright moonlight nights. The mean density for all phyllosoma stages decreased rapidly with depth, i.e., from 0.70/1000 m3 at the surface to 0.04/1000 m3 at 25 to 35 m, indicating that the vertical movements at night are not very extensive. The density of early-stage phyllosoma larvae in the surface at night showed no relationship to micronekton biomass (measured as wet weight). Density of late-stage phyllosoma larvae at the surface at night increased slightly, but significantly, with increase of micronekton biomass, possibly indicating similar behavioural responses to light or some other factor(s). The distribution of cast exuviae of final-stage phyllosoma larvae indicated that metamorphosis to the puerulus phase can occur more than 100 miles (161 km) from shore. Moreover, 80% of the puerulus larvae caught were within 80 miles (129 km) of the shore. Mean densities of puerulus larvae taken at and below the surface at night were 0.04/1000 m3 and 0.10/1000 m3, respectively, although total numbers were low. This evidence indicates that, after metamorphosis, the puerulus larvae return to the coastal environment at some subsurface depth.