Early Postlarvae Research Articles

Growth, metabolic rate, and digestive enzyme activity in the white shrimp Litopenaeus setiferus early postlarvae fed different diets.

Growth rate, soluble-protein content, oxygen consumption, ammonia excretion, and digestive-enzyme activity were studied in Litopenaeus setiferus early postlarvae under four feeding regimens that included combinations of freshly hatched Artemia nauplii, microparticulate commercial diet, and algae. Growth and of postlarvae fed a mixed diet were significantly higher. Artificial diet used alone caused the lowest growth, lowest soluble-protein content, higher ammonia excretion, lowest O:N ratio, and higher proteolytic and amylase activities. The artificial diet stimulated proteolytic activity and ammonia excretion of postlarvae, apparently in response to some deficiency in protein composition of the diet. Based on results in growth, soluble-protein content, enzymatic activity, and metabolic substrate, we determined that partial substitution of Artemia nauplii by artificial diet, with or without addition of algae when rearing early postlarval stages, will benefit the growth and nutritional state of L. setiferus postlarvae.

A long-term study of the recovery of the macrozoobenthos on large defaunated plots on a tidal flat in the Wadden Sea

The process of recovery of the macrozoobenthos community on tidal flats after disturbance by anoxia was studied by monitoring changes in the macrozoobenthos over periods of up to 4.5 year within and around eleven defaunated squares of about 120 m 2 each. Regardless of the season, nearly all species that were present in the surrounding area had settled again in the central parts of the plots within 6 months, though their numbers were generally low if only a winter half-year had elapsed. The total numbers of macrobenthic animals reached values similar to those of the surrounding areas as soon as the recovery period had included at least one summer. Numerical recovery thus proceeded much faster if it started in spring than in autumn. As opposed to species richness and total number of animals, biomass recovery needed several years, as did the recovery of the size and age structure of the long-lived species. Most species settled primarily as early postlarvae in summer, a few species ( Macoma balthica, Arenicola marina) also in high numbers as juveniles in winter. Moreover, several species showed slow colonisation in all seasons by adults transported by tidal currents or moving across the sediment. Seasonal migration abilities of the constituent species and their life stages appear to be the most important mechanism explaining the course of the recovery of the infaunal community on tidal flats. The extraordinarily successful settlement of larvae of several species within still sparsely populated plots led to (sometimes substantially) higher densities of these species within than outside the plots. Such abundance overshoots were not only frequently observed in short-lived opportunistic species (such as Pygospio elegans and Capitella capitata) but also in the juveniles of several long-lived species (such as Macoma balthica and Mya arenaria). It is concluded that inhibition outside rather than facilitation within the plots was an important cause of these abundance overshoots.

Nutritional effects on body composition, energy content and trypsin activity of Penaeus japonicus during early postlarval development

The growth, elemental (C, N, H) and biochemical (lipid, protein) composition, energy content and trypsin activity of Penaeus japonicus early postlarvae (PL 1–PL 20, as days after metamorphosis) fed under a commercial hatchery regime were measured. From PL 1 to PL 4, freshly hatched Artemia nauplii were used, followed by enriched Artemia nauplii (PL 5–PL 9), and a prepared diet from PL 10 to PL 20. Survival for the total experimental period was 80% and daily gain in absolute values of dry weight, energy and elemental composition was observed. Significant increment ( P<0.05) of relative values of carbon, hydrogen and energy was verified from PL 1 to PL 3 as well as increases in protein and lipid content from PL 1 to PL 5. In the period PL 10–PL 20, carbon, hydrogen and energy content decreased significantly ( P<0.05). This may have been due to the poor quality of diet supplied after PL 5, which possibly caused malnutrition. During this period, lipid was a major source of energy for the postlarvae. Body protein of postlarvae as determined by nitrogen content (N×6.25) was overestimated after PL 5, which indicates to a possible role of the non-protein nitrogen fraction under poor feeding conditions. Protein-specific trypsin activity showed significant increment ( P<0.05) at periods PL 1–PL 5 and PL 15–PL 20, which may indicate a possible influence of diet composition. It is concluded that this type of approach may be useful as a tool to assess the nutritional condition of cultivated shrimp, during postlarval stages.

Hinge Development and Functional Morphology in the Larvae and Early Postlarvae of the Boring Bivalve, Barnea manilensis (Pholadidae)

Hinge Development and Functional Morphology in the Larvae and Early Postlarvae of the Boring Bivalve, Barnea manilensis (Pholadidae)

Dietary phosphatidylcholine requirements in larval and postlarval Penaeus japonicus Bate

Three nutritional experiments were carried out to investigate the effect of dietary phosphatidylcholine (PC) on the growth (length, weight and metamorphosis) and survival (rearing and stress) of larval and postlarval Penaeus japonicus Bate. Purified soybean phosphatidylcholine (SPC, 95% purity), hen egg-PC (EPC, 94% purity), and de-oiled soybean lecithin (DSL, PC 23% purity) were used as sources of dietary PC. The results indicated that optimal metamorphosis in larval P. japonicus was obtained at levels of 15–30 g kg−1 of dietary SPC. Feeding trials with postlarval P. japonicus showed that low levels of dietary SPC (15 g kg−1) were more beneficial than higher levels of SPC (30 g kg−1) or DSL (65 g kg−1), although early postlarvae (<3 mg dry weight) presented a higher requirement for PC than later stages. Shrimp fed the 150 g kg−1 PC-supplemented diets exhibited significantly better resistance to salinity stress than those fed a PC-deficient diet. A high level of dietary soybean lecithin (65 g kg−1 DSL), providing 15 g kg−1 of dietary PC, was no more effective for young postlarvae of P. japonicus than 15 g kg−1 of purified PC alone, which suggested that the other phospholipids (mainly phosphatidylethanolamine and phosphatidylinositol) in the soybean lecithin are not required for postlarval shrimp, at least when there is already an adequate source of PC.

Effect of Baculovirus penaei on Growth and Survival of Experimentally Infected Postlarvae of the Pacific White Shrimp, Penaeus vannamei

In a series of experiments conducted to investigate age and size-dependent effects of the baculovirus BP on postlarvae of the Pacific white shrimp, Penaeus vannamei , six groups of specific pathogen-free shrimp of different ages (mysis 2-3 through PL 25) were exposed to the virus and cultured for 15 to 21 days. All BP-exposed groups of early postlarvae (PL 9 or younger) became heavily infected within 2-5 days of initial exposure to the virus, and some of those groups experienced high mortalities compared to the noninfected controls. Postlarvae that survived the infection had highly variable and significantly reduced growth, as determined by dry weight, compared to controls. Exposure of older postlarvae to BP produced a high prevalence of infection, but with little effect on either survival or growth. One group of shrimp exposed to BP at PL 9 was cultured for 49 days. Postlarvae that survived the infection were significantly smaller than the noninfected controls for the first 4 weeks following exposure to the virus; however, the effect of BP on long-term growth of infected postlarvae appeared minimal. To determine the effect of BP on nutritionally stressed shrimp, groups of noninfected and previously infected postlarvae (PL 13-14) of similar size were deprived of food for 10 days. Less than 2% of the infected postlarvae survived the 10-day starvation period compared to 52% survival of the noninfected postlarvae.

Variability in dry weight and vertical distributions of decapod larvae in the Irish Sea and North Sea during the spring

Decapod larvae and early post-larvae were extracted from detailed vertically stratified samples taken during research cruises in the Irish Sea from April to early June 1988 and in the North Sea in June 1989. The total dry weight of decapods was 4 to 106 mg m-2 which represented 0.5 to 8.6% of the total dry weight of zooplankton. The vertical distributions of abundant species were examined in relation to physical and biological variables.Nephrops norvegicus andPagurus bernhardus were found nearer to the surface during the spring bloom in April than after the bloom in May. In the near-surface waters of the North Sea in June, larvae ofLiocarcinus spp. were more abundant than those of other decapods. Diel migrations varied, apparently due to differences in the physical structure of the water column and the distribution of potential food. Conventional migrations were modified or absent in stratified areas when near-surface concentrations of chlorophyll were present and in well-mixed water. Few significant ontogenetic variations were found. The most striking case was ofLiocarcinus spp. larvae during the day in stratified water in the North Sea, where the early zoeal stages (at a mean depth of <6 m), the fifth zoeae (15.5 m mean) and the megalopas (26.7 m mean) occupied different positions in the water column.

Larval and early postlarval shell morphology of several venerid clams

Shell morphological features of the larvae and early postlarvae of species from two venerid (Mollusca: Lamellibranchia) subfamilies, Chioninae (Mercenaria mercenaria, M. campechiensis, M. campechiensis texana and Chionecancellata) and Pitarinae (Pitar morrhuanus), were examined using scanning electron microscopy. A single elongated fold on the anterior half of the left valve became more robust and a small fold in the centre of the right valve increased in length along the hinge line throughout the larval period. A MANOVA of shell length, shell height and provinculum length detected statistically significant (P) differences between the larval shells of Chioninae and Pitarinae, and within the Mercenaria.

A Thyroxine Surge during Development of Black Sea Bream Larvae and its Ecological Implication in Inshore Migration.

The tissue concentration of L-thyroxine (T4) was measured by radioimmunoassay for whole bodies of laboratory-reared black sea bream larvae from 12 to 38 days after hatching. T4 level was less than 2ng/g body wet weight in early postlarvae. It increased markedly from 1.7ng/g on day 19 to 7.0ng/g on day 24, and then gradually decreased to 2.4ng/g by day 33, followed by the second elevation to 5.0ng/g on day 38. The first surge, occurring on day 24, corresponded to the notochord postflexion phase (Fukuhara's I stage) at which average standard length was 6.1mm. Previous field research on the early life history of this species suggests that this phase corresponds to the critical phase when the larvae migrate from coastal waters to near-shore nursery areas. Thus, it seems possible that thyroxine is involved in habitat transfer during the early ontogeny of the black sea bream.

Na +-K + ATPase and carbonic anhydrase activities in larvae, postlarvae and adults of the shrimp Penaeus japonicus (Decapoda, Penaeidea)

1. 1. Activities of Na +-K + ATPase and carbonic anhydrase were measured through the early post-embryonic development of Penaeusjaponicus. In adults, only the Na +-K + ATPase activity was measured. 2. 2. ATPase activity was variable in the successive development stages. From zero in nauplii, the activity slightly increased in zoeae, and rose sharply in mysis stages 2 and 3. 3. 3. A further significant increase in activity was noted at the transition from late mysis to early postlarvae, concomitant with a change from the larval osmoconforming pattern of osmoregulation to the postlarval and adult hyper-hyporegulating pattern. 4. 4. The activity of Na +-K + ATPase, measured in isolated cephalothorax, increased from PL3 to PL4 to its maximum value in PL5; at this stage, osmoregulatory capacity was fully efficient. 5. 5. In young stages of P. japonicus, the variations in Na +-K + ATPase activity appear correlated with the development of osmoregulatory ultrastructures, and with osmoregulation and salinity tolerance. 6. 6. These results are discussed with regard to their ecological and physiological implications. 7. 7. In adults, the activity of Na +-K + ATPase was high in gills and epipodites and no activity was detected in branchiostegites. These results are related to the ultrastructure of these organs. 8. 8. The activity of carbonic anhydrase did not change significantly in larval and postlarval stages. 9. 9. From these results, it is proposed that the effector sites of osmoregulation are located in branchiostegites, pleurae and epipodites in postlarvae, and in epipodites and mainly in gills in adults.

Abundance of nauplii and protein synthesis activity of adult female copepods in the Kuroshio front during the Japanese sardine spawning season

In order to point out the potential importance of the Kuroshio front as a feeding ground for the early post larvae of the Japanese sardine, distributions of copepod nauplii—the principal food for the larvae—were investigated.

Ontogenetic Changes in Enzyme Distribution and Midgut Function in Developmental Stages of Penaeus setiferus (Crustacea, Decapoda, Penaeidae).

Ultrastructure and histochemical distribution of enzymes were examined in the midgut of larval and postlarval stages of Penaeus setiferus. Acid phosphatase and esterase activities were present in all gut tissues at all stages. Protease activity was present in the anterior and lateral midgut caeca, as well as in the anterior portion of the midgut trunk (MGT) of larvae and early postlarvae (PL1-PL4). Amylase activity could not be detected histochemically in larvae or early postlarvae, even though it was detected in assays of whole-animal homogenates. In later postlarvae, both protease and amylase activities were present in the hepatopancreas and anterior MGT, but were absent from the anterior midgut diverticulum. In larvae, alkaline phosphatase activity is present throughout the midgut, suggesting that absorption is widespread. In juveniles, activity is restricted to the hepatopancreas and regions of the MGT within the cephalothorax. The abdominal MGT (or "intestine") is no longer absorptive by the time the hepatopancreas has attained its adult form. Although epithelial cells of the MGT synthesize protein and produce electron-dense secretory vesicles, they are substantially different in ultrastructure from those cells in the hepatopancreas responsible for digestive enzyme synthesis and secretion. Epithelial cells of the larval anterior and lateral midgut caeca are structurally and functionally similar to cells of the postlarval hepatopancreas. However, the lateral midgut caeca retain these features as they transform into the hepatopancreas, while the anterior midgut caeca lose these functions as they degenerate into the anterior diverticulum and change in ultrastructure during early postlarval development. The anterior and posterior midgut diverticula of postlarvae are similar ultrastructurally even though they differ in ontogenetic history.

Use of the Nematode Panagrellus redivivus as an Artemia Replacement in a Larval Penaeid Diet

Abstract Penueus vannumei larvae (P2 through M3) and early postlarvae (&lt;24 h old postlarva) were fed diets consisting of algae‐only, nematodes (Panugrellus redivivus) plus algae or Artemia plus algae. Growth (dry biomass gain) of second and third stage protozoea larvae fed the nematodealgae diet was significantly better than that of larvae fed the Artemia‐algae diet. From the first mysis through the postlarval substage (&lt;24 h old), growth of shrimp fed the nematodealgae diet equalled that of larvae fed the Artemia‐algae diet. All larval substages fed nematodes plus algae accumulated significantly greater biomass than those fed a diet of only algae. Survival and percent metamorphosis of larvae fed nematodes plus algae did not differ significantly from that of larvae fed either Artemia plus algae or algae alone. A nematodealgae feeding regime, which potentially yields growth, survival and metamorphosis equal to that obtained on the standard Artemia plus algae regime, is proposed for P. vannamei.

Ontogenic changes in isozyme patterns of Penaeus species

1. 1. The electropherograms of four developmental stages, early protozoea, early mysis, early postlarva, and adult are compared. 2. 2. Eight enzyme stains and a Coomassie Blue stain were employed in the comparisons. 3. 3. The electropherograms exhibit differences among developmental stages and among species. Some stage-specific protein bands are present. 4. 4. Complexity of electropherogram pattern tends to increase with age in most of the staining systems.

THE EFFECTS OF FACTORS IMPORTANT IN SEMI-ARID ENVIRONMENTS ON THE EARLY DEVELOPMENT OFUCA SUBCYLINDRICA

Lack of food and salinity extremes are conditions encountered by the early life stages of Uca subcylindrica in their semi-arid habitats, where nursery areas are temporary rainfall puddles. Several characteristics of the larvae and early postlarvae promote high survivorship in these extreme environments. When starved, yolk reserves in the two zoeal stages lasted through metamorphosis to the megalopal stage and allowed ≥50% survival for 11 days after that. Food was required by the megalopae, however, before molt to crab I occurred. Larvae and early postlarvae survived and developed in a wide range of salinities under laboratory conditions—0.08 to ∼50‰. The ability to hyperosmotically regulate the blood was present at hatch. Tolerance to higher salinities increased with successive stages as the ability to hypo-osmotically regulate improved. The early stages of other fiddler crab species are unlikely to survive and develop in the conditions experienced by the zoeae, megalopae, and early crabs of U. subcylindr...

若狭湾におけるカレイ目魚類の初期生活史の研究 Ｘ イシガレイの初期生活史

General morphology of the eggs, larvae and juveniles of a flounder Kareius bicoloratus were described. There is some variation in relationship between stage and body length in larvae, especially at the metamorphosis stages. It may mean the variation in the size at settlement. Judging from records of occurrence of eggs, actual spawning period may be from January to February. Annual occurrence of larvae was surveyed by means of underwater fish lamp, and it appeared that the number and periold of larval occurrence at the inner part of Maizuru Bay showed remarkable variations from year to year during 1974-1979. Eggs were caught in he offshore region of the mouth of the Yura River, prelarvae were also caught in the same region, early postlarvae were around the mouth of Maizuru Bay, late postlarvae were mainly in the Maizuru Bay, and nearshore region of the mouth of the Yura River. Early juveniles were captured in the water closs to the shore of the Yura River and Maizuru Bay, and these areas may be their nursery ground. These facts indicate that an inshore movement took place during the larval stage. Analysis of the gut content showed that the food items were copepod eggs and nauplii in early postlarvae, copepods (mainly Centropages sp.) in late postlarvae, and mysids and amphipods in early juveniles. The early life histories of two species, Kareius bicoloratus and Limanda yokohamae, were compared.

Decapod Crustacea from the International Indian Ocean Expedition. Larval and post-larval stages ofTrachypenaeus curvirostris(Stimpson) (Penaeinae)

Summary Developmental stages of Trachypenaeus curvirostris (Stimpson) from the second protozoea to the early post-larva are described and figured. The diagnostic characters of the larvae of Trachypenaeus are the absence of supra-orbital spines and hepatic spines in all stages and the presence of a long rostrum and a small dorsal organ in the protozoeae. The species recorded has a wide range of distribution in the Indian Ocean, particularly in the northern Indian Ocean, in the Bay of Bengal and off the southwest coast of India.

若狭湾におけるカレイ目魚類の初期生活史の研究 ＶＩ ヒラメの初期生活史

The early life history of a flounder Paralichthys olivaceus (TEMMINCK et SCHLEGEL)was studied in the western Wakasa Bay, the Japan Sea. General morphology and characteristics of the larvae and juvenile ranging from 3.25mm to 13.20mm BL, were described. The characteristic features of this fish in early larval stages were elongations of the first 5 dorsal fin rays and distribution patterns of melanophores on the body surface. There is some variation in relationship between stage and boby length in larvae, especially at the late metamorphosis stage. It may mean the variation in the size at settlement. Judging from records of occurrence of early larvae, actual spawning may occur in the western Wakasa Bay during a relative long period from March to May. Early postlarvae were caught mainly off the coast of Wakasa Bay, and late postlarvae were caught mainly in the nearshore regions. In the period of pelagic larval stage, an inshore movement must have taken place. Early juveniles were captured in the shallower water of the estuary of Yura River, and this area may be their nursery ground. Annual occurrence of larval occurrence showed remarkable differences from year to year. Analyses of the gut content showed that the food items were copepod nauplii in early postlarvae, Oikopleura spp. in late postlarvae, and copepods and mysids in early juveniles. Some considerations on the daily food intake of the larvae under natural conditions were discussed.

EXPERIMENTAL CULTURE OF THE OCEAN QUAHOG, Arctica islandica

AbstractLarvae and early postlarvae of the ocean quahog, Arctica islandica, were reared under experimental hatchery conditions. Mature eggs were stripped from ripe adults and exposed to a dilute solution of ammonium hydroxide for various lengths of time prior to addition of stripped sperm. The larval clams were reared through settlement and metamorphosis using the Wells‐Glancy (centrifuged, incubated seawater) method of algal culture and/or modifications of standard hatchery techniques developed by Loosanoff and Davis. Experimental cultures were maintained at various temperatures ranging from 8.5° to 14.5°C. At temperatures of approximately 13°C, the minimum time to settlement was 32 days, while settlement was not observed in a culture maintained between 8.5° and 10.0°C until approximately 55 days after fertilization. Larval growth rates were significantly lower in the culture maintained at 8.5–10.0°C than in cultures maintained at 11.0–14.5°C. An optical micrograph sequence of larval stages from the straight‐hinge stage through metamorphosis is presented to facilitate identification of Arctica islandica specimens isolated from plankton samples. While various workers have reported exceedingly low growth rates of juvenile and adult Arctica, growth rates of larval Arctica appear to be fairly “typical” of rates encountered within the class Bivalvia.

若狭湾におけるカレイ目魚類の初期生活史の研究 ＩＩＩ マコガレイの初期生活史

The early life history of a flounder Limanda yokohamae (GÜNTHER) was studied in the western Wakasa Bay, the Japan Sea. General morphology and characteristics of the larvae and juveniles ranging from 3.05mm to 9.90mm BL, were described. Judging from records of occurrence of early larvae, actual spawning may occur in the western Wakasa Bay during the short period from late January to early February. Prelarvae were caught mainly off the mouth of Maizuru Bay, early postlarvae were caught around the mouth of the Bay, and late postlarvae were caught mainly in the central part of the Bay. Early juveniles were captured in the beach of the Bay, and this area may be their nursery ground. Analyses of the gut contents showed that the food items were phytoplankton, veliger larvae and copepod nauplii in prelarvae, veliger larvae, copepod nauplii and copepods in postlarvae, and copepods, nematoda and polychaeta in early juveniles.