Shrimp Eggs Research Articles

The effect of vitamin A supplementation in broodstock feed on reproductive performance and larval quality in Penaeus chinensis

The effect of feeding four semi-purified diets A1, A2, A3, A4, containing different vitamin A acetate levels 0, 20, 40, 60 mg kg−1 diet, respectively, on fecundity, egg hatching rate, larval survival rate and vitamin A content in eggs of Chinese shrimp (Penaeus chinensis) broodstock was compared with a fresh clam diet (control) in a 60-day feeding trial. The broodstock shrimp fed the diet with 60 mg kg−1 vitamin A acetate added exhibited significantly higher fecundity (P < 0.01). Hatching rate was highest with diet A4 (P < 0.05), whereas hatching rates were similar fed diets A1, A2, A3. Increasing levels of vitamin A in broodstock diet resulted in improvement in larval quality. The vitamin A levels in shrimp eggs from broodstock fed with diet A4 were higher compared with those from broodstock fed with diet A1, A2 (P < 0.01). The fecundity and hatching percentages were positively correlated with the vitamin A content in eggs in the present study. The results of this study showed that higher level of vitamin A in broodstock diet may have positive effects on fecundity and larval quality in P. chinensis.

Abundance of potentially pathogenic micro-organisms in Penaeus monodon larvae rearing systems in India

Monodon baculovirls (MBV), external fouling organisms (EFO) and bacteria (especially Vibrio species) were monitored during 1996-1997 at nine different Penaeus monodon rearing hatcheries in India. Total cultivable heterotrophic bacteria, Vibrio-like-bacteria, presumptive Vibrio harveyi, Vibrio anguillarum, Vibrio vulnificus counts were determined from shrimp eggs, post larvae, rearing tank water, source sea water, feed (Artemia nauplii and microencapsulated feed). The MBV infected post larvae and their environment showed higher Vibrio-like-bacteria than uninfected post larvae. An overwhelming predominance of presumptive Vibrio harveyi and Vibrio anguillarum was observed in post larval rearing tank water, MBV infected and uninfected post larvae. Vibrio-like-bacteria in Artemia nauplii clearly showed the possible source of these pathogenic bacteria in the hatchery environments. Quantitative analysis of Vibrio-like-bacteria in hatcheries revealed that when the Vibrio-like-bacteria increases to 2 x 10(2) CFU mortality of the post larvae occurs. Abundance of these micro-organisms in hatchery samples indicated that they are opportunistic pathogens which can invade the shrimp tissue, subsequently cause disease when the post larvae were under stressful conditions.

Lipid and fatty acid composition of Antarctic shrimp eggs (Decapoda: Caridea)

Eggs of the decapod shrimps, Chorismus antarcticus, Nematocarcinuslanceopes and Notocrangon antarcticus were taken to analyse their morphometric, lipid and fatty acid composition. Almost all females carried undifferentiated eggs (stage I). The average number of recently extruded eggs was lowest in C. antarcticus with 163 eggs, and highest in Nematocarcinus lanceopes with 1,220 eggs, while Notocrangon antarcticus produced on average 350 eggs. The lipid content (% of dry mass) of the eggs was 18.8% for C. antarcticus, 14.3% for Notocrangon antarcticus and 18.1% for Nematocarcinus lanceopes. Dominant lipid classes in eggs of all species were phospholipids and triacylglycerols. The storage lipid, triacylglycerol, was slightly elevated in the eggs of Nematocarcinus lanceopes (mean of 52.7%) compared to the other two species. The fatty acid compositions of the decapod eggs were similar in the three species. Dominant fatty acids were 20:5(n-3), 18:1(n-9), 16:1(n-7), 16:0 and 18:1(n-7), comprising 75.8–78.4% of total fatty acids. Among the species, the eggs of C. antarcticus had the highest proportions of polyunsaturated fatty acids (39.6%), dominated by 20:5(n-3), and the lowest percentage of monounsaturates (41.8%). The eggs of Nematocarcinuslanceopes and Notocrangonantarcticus contained almost the same proportion of polyunsaturated fatty acids (28.0% and 28.4%, respectively), whereas Nematocarcinus lanceopes had the highest amount of monounsaturates due to the dominance of 18:1(n-9). Based on our findings, we assume that eggs produced by polar decapod crustaceans do not contain substantially more lipids than related species from temperate or tropical regions. However, additional studies are necessary to substantiate any general conclusion about the relationship of egg lipid content and composition with climatic zones.

Comparative size, biomass, elemental composition (C, N, H), and energy concentration of caridean shrimp eggs

Summary In the evolution of decapod crustaceans, interspecific variation in egg size is considered as an important life-history trait that is linked with the duration of embryonic and larval development, the number and type of larval stages, and with juvenile size. Aiming to provide a quantitative characterization of reproductive traits in related decapod taxa differing in lifestyle (freshwater, estuarine, marine) and geographic-climatic distribution (tropical-temperate), we compared size, biomass, and elemental composition of eggs of caridean shrimps from three families: seven species of Palaemonidae (three congeners of Macrobrachium: M. olfersii, M. carcinus, M. acanthurus; four species of Palaemon: P. northropi, P. pandaliformis, P. elegans, P. adspersus), two Atyidae (Potimirim potimirim, Atya scabra), and one Pandalid (Pandalus montagui). Egg size was measured as larger and smaller diameter (D1 D2), volume was calculated from D1 and D2, and biomass was measured as dry mass (W), carbon (C), nitrogen (N), hydrogen (H), and energy (E, estimated from C) contents. The smallest size and lowest biomass were found in the eggs of two freshwater atyids (both originating from Brazil); the largest size occurred in a marine species, P. montagui (from the North Sea); and intermediate values in freshwater, estuarine, and marine palaemonid species (from Brazil and the Baltic Sea, respectively). Among the Palaemon species, the most limnic (P. pandaliformis) showed a significantly larger egg size and volume (P<0.001) than the estuarine and marine congeners, P. elegans, P. adspersus and P. northropi. This suggests that the generally postulated relationship between egg size and lifestyle (freshwater vs. estuarine or marine) may appear at a generic but not at the family level. On the other hand, individual biomass (in μg or Joules per egg) of early eggs was significantly higher in P. elegans and P. adspersus, indicating interspecific variability in biomass and energy concentration (in μg or Joules per unit volume, mm3). Generally lower biomass concentrations in early eggs of freshwater shrimps may be caused by a higher average water content. Eggs in late embryonic stages were generally larger than earlier eggs of the same species, reflecting an increase in the water content, while an increasing D1:D2 quotient indicated an increasingly elongated egg shape. The biomass per egg decreased during embryonic development due to metabolic degradation of organic reserves. As a consequence of inverse ontogenetic changes in size and organic biomass of developing eggs, the mass-specific biomass values (C, N, H in percent of W; E in Joules per mg W) and volume-specific concentrations (μg or Joules per unit volume) decreased. This change was consistently stronger in the C, H, and E contents than in other measures of biomass (W, N). In consequence, the C:N mass ratio also decreased, suggesting that lipid degradation rather than protein utilization was the principal fuel for embryonic development. Our results indicate high intra- (mainly developmental) and interspecific variation in reproductive traits of closely related species. While volume-specific biomass and energy concentrations of early eggs appear to be associated with variation in habitat salinity (freshwater, brackish, marine), individual egg size and biomass may be related more with the climatic-geographic distribution (temperate, tropical) of different taxa.

Toxicity of lapachol and isolapachol and their potassium salts against Biomphalaria glabrata, Schistosoma mansoni cercariae, Artemia salina and Tilapia nilotica

The toxicity of soluble derivatives (potassium salt) of lapachol and isolapachol in different stages of the life cycle of Schistosoma mansoni is evaluated. The potassium salts of isolapachol and lapachol showed significant molluscicidal activity against the adult snail (LC 90<7 ppm) and snail egg masses (LC 90<3 ppm). Cercaricidal assays revealed strong activities for both compounds. Lethality assays against brine shrimp eggs ( Artemia salina Leach) indicated very high toxicity for the potassium salt of isolapachol (LC 90=1.54 ppm), differently from the potassium salt of lapachol that can be considered non toxic (LC 90=176.3 ppm). The same tendency is observed with piscicidal activity, for which the isolapachol salt has showed higher toxicity. The obtained selectivity ratios concerning LC 50 and LC 90 for lapachol, in relation to Tilapia nilotica lethality assay are 2.33 and 1.26, respectively. Despite the piscicidal toxicity, the use of the salt of lapachol can be recommended for field tests in Schistosomiasis, with caution.

Prevalence, geographic distribution, and fitness effects of Microphallus turgidus (trematoda: Microphallidae) in grass shrimp (Palaemonetes spp.) from coastal Georgia.

Grass shrimp, Palaemonetes pugio Holthuis and P. vilgaris (Say), were collected at 11 localities along the coast of Georgia and surveyed for digenetic trematode metacercariae. The effect of trematode infection on grass shrimp fitness was also examined. Microphallus turgidas (Leigh) was the only trematode observed. The prevalence of metacercarial cysts of this parasite in P. pugio (75%) was higher than in P. vulgaris (24%), as were the mean intensity, abundance, and population density (no. cysts/cm host body length) of the parasite. Infected shrimp were found at every collection locality and parasite prevalence and density were greatest in P. pugio from higher salinity localities (> or = 20 parts per thousand [ppt]). There was no relation between host body size and parasite density in P. vulgaris, and parasite density increased with host body size in P. pugio, suggesting that the parasite does not affect host survival. There was no relation between parasite density and shrimp egg mass, but nonovigerous female P. pugio were more heavily infected than ovigerous ones. In addition, 1 metacercaria of M. turgidus in each of 2 specimens of P. vulgaris was parasitized by the haplosporidian Urosporidium crescens De Turk. This represents a new shrimp host record for this hyperparasite.

A Brine Shrimp Bioassay for Measuring Toxicity and Remediation of Chemicals

A bioassay using Artemia franciscana (brine shrimp) was adapted to measure the toxicity of household chemicals. One project is described in which students collect dose-response curves for seven commercial flea-killing products. Next, groups of students researched the insecticidal ingredients of the flea products. On the basis of the structures of the active ingredients, they chose remediation methods to make the flea product less toxic to brine shrimp; procedures included copper-catalyzed hydrolysis, adsorption onto activated charcoal, bleach treatment, and photodegradation. No special equipment or supplies are necessary for the bioassay other than the brine shrimp eggs, which can be obtained at any aquarium store.

Dispersal of the fairy shrimp Branchinecta coloradensis (Anostraca): Effects of hydroperiod and salamanders

The absence of fairy shrimp (Anostraca) from permanent ponds and lakes is hypothesized to be the result of vertebrate predation. However, hatching cues for anostracan diapausing eggs include factors associated with the filling of temporary pond basins, and desiccation often increases the fraction of eggs that hatch. Thus, it is possible that in some species, eggs dispersed to permanent habitats never hatch, and vertebrate predation is not the proximate factor limiting distributions. We experimentally transplanted live egg‐bearing females of the fairy shrimp Branchinecta coloradensis into permanent and temporary ponds in small chambers and allowed the chambers to overwinter in situ. There was no discernible effect of pond drying on hatching success (mean success = 50.9%). We also determined whether metamorphic salamanders (Ambystoma tigrinum nebulosum) could disperse viable fairy shrimp eggs by feeding on B. coloradensis in one pond and defecating in another. Hatching success for a salamander “ingested” treatment was estimated as 0.9%. Results of a third experimental treatment suggested that the eggs being carried by females were not fully mature, so that ingestion resistance might vary throughout the reproductive period of B. coloradensis. By combining these results with data on salamander movement and diet, we estimated salamander‐mediated dispersal rates for fairy shrimp eggs. Metamorphic A. tigrinum nebulosum sp. are likely to be dispersing thousands of B. coloradensis eggs among ponds annually. Because our results demonstrate that dispersal between ponds can occur in large numbers, they support the prevailing hypothesis that vertebrate predators limited to permanent ponds are the proximate mechanism preventing the invasion of fairy shrimp.

Simultaneous determination of α-tocopheryl acetate and tocopherols in aquatic organisms and fish feed

In aquaculture, α-tocopheryl acetate (α-TA) is the main source of vitamin E used to fortify fish feed. α-TA in fish is often determined indirectly, i.e., by alkaline hydrolysis, followed by quantitation of “total α-tocopherol” (α-T) and subtraction of the natively present α-T. The aim of this study was to develop an HPLC method for the simultaneous quantitative determination of α-TA and free tocopherols in aquatic organisms and fish feed. The assay consists of a simple extraction with methanol containing butylhydroxytoluene (BHT) as an antioxidant, followed by reversed-phase chromatography with consecutive UV and fluorescence detection of α-TA and tocopherols, respectively. The peak of the internal standard tocol in the fluorescence trace was used for quantitation. Linearity was achieved over the range of 0.2 to 4.2 μg α-TA per ml extract of Artemia nauplii, which would correspond to 30.7 to 614.4 μg/g dry mass. The within-run coefficient of variation was 1.9% at a level of 310 μg/g dry mass. The recovery of α-TA ranged from 97.7 to 100.8% (concentration=2.1 and 20.5 μg/ml, n=6). The detection limit was about 7 ng and the quantification limit on spiked samples was 0.2 μg/ml. This method was routinely applied to determine α-TA and α-, γ- and δ-tocopherol (α-T, γ-T, δ-T) simultaneously in Artemia, fish feed, shrimp eggs and various other aquatic organisms.

A Study of &lt;i&gt;Artemia&lt;/i&gt; in Lagkor Co, Tibet:II.Nutrient

卤虫包括成体、无节幼体和卤虫卵,蛋白质、氨基酸、脂肪酸等营养成分的含量是评价卤虫质量的主要标准,因为摄食动物饵料效果取决于氨基酸、脂肪酸的组成与含量.西藏拉果错卤虫的营养成分含量较高,1996、1997年盐湖研究中心连续取样测定,其蛋白质含量成体接近20%,无节幼体约 55%,脱壳卵近 50%;粗脂肪成体 3%,无节幼体和脱壳卵均为 15%左右;氨基酸总量成体 18%,无节幼体近 50%,脱壳卵 44%左右在对 1997年样品进行脂肪酸测定后发现,成体不饱和脂肪酸达83%,无节幼体91%以上,脱壳卵超过87%;三种高级不饱和脂肪酸(20∶2,20∶4,20∶5)HUFA含量:成体近8%,幼体和脱壳卵均超过20%;三种必需脂肪酸(18∶2,18∶3,20∶5)EFA含量:成体为16%,幼体21%,脱壳卵26%;无节幼体和脱壳卵的二十碳五烯酸(20∶5)EPA含量均在 18%以上,较我国新疆、青海、内蒙古、 山西、河北地区的盐湖卤虫和天津、海南盐田卤虫的(20:5)EPA含量高,脱壳卵的不饱和脂肪酸总量比已知的国内外其它盐湖卤虫的相应指数高;The content of nutrients which are composed of protein, Amino acid and fatty acid etc of Artemia (including assess the quality of nutrients and brine brine shrimp eggs) is the main criterion to Artemia, because the food value of animal of prey depends on the constituent and content of amino acid and fatty acid.The nutrient of the Artemia in Lagkor Co (Lake) of Tibet is of high value and a succession of samples taken by R & D Centre of Saline Lake and Epi-thermal Deposits (CAGS) were monitored in 1996 and 1997.The protein content of adult brine shrimp is nearly 20%, and that of nauplius and decapsulated brine shrimp eggs about 55% and 50% respectively. The raw fat content of adult brine shrimp is 30% and that of both nauplius and decapsulated brine shrimp eggs is about 15%. The total amount of amino acid of adult brine shrimp is 18% and that of nanplius and decapsulated brine shrimp eggs about 50% and 44% respectively. Among fatty acids the unsaturated fatty acid of adult brine shrimp is up to 83% in samples of 1997 and that of nauplius and decapsulated brine shrimp eggs about 91% and 87% respectively.For three unsaturated fatty acids, the content of HUFA(20 :3, 20 :4, 20 :5) of adult brine shrimp is nearly 8%, and that of both nauplius and decapsulated brine shrimp eggs exceeds 20%.For three necessary fatty acids, the content of EFA (18 :2, 18 :3, 20 :5) of adult brine shrimp is 16% and that of nauplius and decapsulated eggs is 21% and 26% respectively. The contents of EPA (20:5) of both nauplius and decapsulated eggs are above 18%. The content of EPA of Artemia in Lagkor Co is higher than that of Artemia in salt lakes of Xinjiang, Qinghai, Inner Mongonia, Shanxi, Hebei and that of Artemia in salterns of Tianjin and Hainan.The un-satulated fatty acid content of decapsulated brine shrimp egg in Lagkor Co is higher than that in other lakes at home and abroad.

Experimental Demonstration of the Effects of Clam Shrimp on Turbidity of Microcosms

Abstract The conchostracans (Crustacea: Class Branchiopoda, Orders Laevicaudata and Spinicaudata), commonly called clam shrimp, are inhabitants of temporary wetlands and are well adapted to surviving dry periods. Clam shrimp eggs are highly resistant to freezing, drying, sunlight, and mechanical injury. Reports have indicated that clam shrimp increase turbidity in fish culture ponds and negatively affect fish production The effect of the clam shrimp Caenestheriella belfragei on turbidity was studied by examining the turbidity of laboratory containers with 0–4,848 clam shrimp/m2. Turbidity increased in direct proportion to clam shrimp density at all densities greater than 606 clam shrimp/m2.

CHROMOSOME STUDIES ON THE MARINE SHRIMPS PENAEUS UANNAMEI AND P. CALIFORNIENSIS (DECAPODA)

ABSTRACT Chromosome numbers were obtained from eggs of Penaeus vannamei and Penaeus californiensis,They had 2n = 88 chromosomes. This was confirmed by the haploid chromosome number of n = 44 in testes. No evident karyological difference was observed between these species, in which 4 metacentric, 10 submetacentric, 56 subtelocentric, and 18 acrocentric chromosomes were observed. To obtain mitotic metaphase chromosomes from marine shrimp eggs, 2 methods are described. The effect of colchicine incubation for chromosome condensation was investigated.

Field Introductions and Establishment of the Tadpole Shrimp, Triops longicaudatus (Notostraca: Triopsidae), a Biological Control Agent of Mosquitos

The tadpole shrimp (Triops longicaudatus LeConte) is a potential biological control agent for some species of mosquitoes developing in temporary aquatic habitats. It is an effective larval predator that also actively deters mosquito oviposition. Its use in practical control programs depends in part on its ability to establish permanent populations where it is introduced. Introductions of its desiccation-resistant eggs (both lab-reared and field-collected) as well as gravid adults were made in 16 ponds in southern California. Tadpole shrimp density was monitored over five floodings from Fall 1991 through Summer 1992. The tadpole shrimp was able to colonize and persist in 94% of the ponds. All methods of introducing T. longicaudatus were successful, but its hardy egg is the preferred stage for field distribution. The hatching rate for lab-reared shrimp eggs in the ponds ranged from 13.7 to 19.4% (X = 15.9%, N = 1135-2353/pond). In a following experiment, a high density of tadpole shrimp was shown to have a significant negative impact on mosquito larvae (Culicidae) (P < 0.05), and on nontarget midge larvae (Chironomidae) (P < 0.05), but not on two other abundant insects-mayflies (Baetidae) or brine flies (Ephydridae).

Sexual dimorphism and food habits of the clingfish, Diademichthys lineatus, and its dependence on host sea urchin

Stomach contents of the clingfish Diademichthys lineatus, 10–56 mm standard length, revealed changes in food habits with growth and sexual differences. Soon after settlement, D. lineatus obtained food from their host sea urchin (genus Diadema) and other associated symbionts. They became less dependent on the host with growth. The juveniles ate pedicellariae and sphaeridia of the host and commensal copepods, whereas the adult fish ate burrowing bivalves in corals as well as tube feet of their host and eggs of a commensal shrimp. The young fish were transitional in their food habits. The change in food habits of the fish coincided with behavioral changes; i.e. enlargement of home ranges and less dependency on the host. The adult females, having a longer snout, ate shrimp eggs and bivalves more frequently than the adult males, which ate tube feet of the host more often than the females did. Sexual difference in food habits was apparent after the sex of the fish became identifiable by comparing snout shapes. The polygynous mating system of this species suggests that conspicuous sexual dimorphism might have developed under sexual selection. However, niche partitioning of food is also likely to be related to this sexual dimorphism.

Effect of drying period and soil moisture on egg hatch of the tadpole shrimp (Notostraca: Triopsidae).

Tadpole shrimp (Triops spp.) are potential biological control agents against larval mosquitoes in temporary ponds and flood-irrigated fields. In some rice field situations, however, they may become pests that uproot and eat young rice plants. In cursory observations, it has been reported that tadpole shrimp eggs do not readily hatch on flooding when the soil or substrate containing eggs is moist before flooding. The relationship between drying (moisture content) of soil and tadpole shrimp hatch was determined in studies conducted in mesocosms at the University of California Aquatic and Vector Control Research facilities at Riverside and at Oasis in the Coachella Valley of southern California. In laboratory hatching trials, an increase in hatch of Triops longicaudatus (LeConte) with declining soil moisture content was demonstrated (t = 8.4, P less than 0.001; r2 = 0.76). In field trials in mesocosms at Riverside, egg hatch increased with increased drying period and declining soil moisture content (G = 29.8, P less than 0.01). No hatch of eggs occurred after 3 d of drying, when soil moisture content was high, but a high level of hatching occurred after 7 and 14 d of drying, when soil moisture declined to low levels. At Oasis, soil moisture did not decrease with drying time because of porous soil and capillary action of water from adjacent flooded mesocosms and thick vegetation covering the pond bottoms. Therefore, hatch rates at Oasis were not associated with the length of the drying period (G = 35, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Decapsulating Brine Shrimp Eggs

Brine shrimp eggs, essential for feeding small fish in hatcheries, require separation from their non-digestible shells and unhatched eggs post-hatching. This document explains the decapsulation process using chlorine removing the outer shell, simplifying separation and sterilizing the eggs. This method improves hatch rates and allows unhatched eggs to be fed directly to fish. The decapsulation procedure involves soaking the eggs in water, treating them with bleach, and rinsing thoroughly. Decapsulated eggs can be stored in brine or hatched immediately in containers with specific conditions. This process adapts to various brine shrimp egg types, ensuring effective hatchery operations. First published June, 1990.

Jelly Layer Formation in Penaeoidean Shrimp Eggs.

Etude histologique et chronologique de la formation de la couche gelatineuse des œufs de crevettes Penaeoidea par microscopies optique et electronique a transmission

NASA 1989: Suddenly It's 1986

Galileo, now set for launch from the shuttle on Oct. 8, 1989, will follow different and far longer path to Jupiter than planned in 1986, not reaching there until 1995. On the way, it will swing past Venus and Earth in 1990 for gravitational assists to increase its speed, take the first close look at an asteroid (Gaspra) the following year, pass Earth again in 1992 for another boost, fly by second asteroid (Ida) in 1993, and finally get to Jupiter more than two years after that. There, probe will descend into Jupiter's atmosphere and the Galileo orbiter will spend 22 months photographing the planet and the Galilean satellites, its four largest moons. NASA's ambitious 1989 science agenda begins, however, with the first launch of U.S. spacecraft to another planet since the Pioneer Venus mission took off in 1978. Like that Pioneer, Magellan is to map the cloud-shrouded surface of Venus by radar. Formerly planned for liftoff in 1988, it is now scheduled to depart from the shuttle on April 28. Planetary scientists often remark that given mission will keep researchers busy for years, but Magellan officials maintain the new craft will supply data for decades of study It should reach Venus in August of 1990. Late December 1989 will see shuttle astronauts deploy the huge Hubble telescope. Astronomers will first spend six months checking it out in orbit from the ground, then as long as 20 years looking at planets, at stars and out almost to the edges of the universe with its 2.4-meter mirror, which will give an unparalleled view because of its position above Earth's distorting atmosphere. Astronauts will periodically repair and replace the telescope's instruments. NASA, in fact, recently approved study of what may be the first of the telescope's second-generation instruments. A combination of near-infrared camera and multi-object spectrometer, it will equip Hubble to study the faint heat emissions from objects such as possible planetary systems now forming elsewhere in the galaxy, some of them first spotted in 1983 by the Infrared Astronomy Satellite. The proposed $80-million instrument's operation will depend on keeping its detectors cold, so they will be mounted within what one official describes as a block of solid nitrogen the size of refrigerator, which is inside dewar cooled by block of dry ice [solid carbon dioxide] inside another dewar. Pointedly not going up by shuttle is the Cosmic Background Explorer, or COBE, designed to sense emissions dating almost from the Big Bang. NASA originally intended to launch COBE from the shuttle, but modified the satellite in the aftermath of the Challenger explosion to ride conventional Delta rocketmaking it the first NASA spacecraft deliberately redesigned to get into space the oldfashioned way. Shuttle astronauts this year should make the long-overdue pickup of device called the Long Duration Exposure Facility (LDEF), which has been waiting passively in orbit since astronauts put it there in 1984. Equipped with no electronics, no moving parts, it consists merely of rack to expose various material and biological samples to the space environment. The original plan was to leave LDEF there for year, but it stayed longer because of the busy shuttle schedule; then Challenger blew up, leaving LDEF still in space, from which NASA expects to retrieve it on Nov. 13. Scientists most interested in LDEF's results include those concerned with life aboard NASA's planned space station. The seeds, dormant shrimp eggs and other life forms in LDEF will have experienced half decade's exposure to cosmic rays, gamma rays and other Earth-orbit influences. When planted, will the seeds have mutated? Will they grow at all? The materials tests range from paints and glasses to computer chips, some of them from the Defense Department. Will, for example, the ceramics essentially fired in their extended but presumably low-level radiation environment hold key to harder materials with greater breaking strengths, for such applications as high-temperature turbine blades? The other major space event of the year, due late in August, was really triggered by the launch of Voyager 2 in 1977. The last planned feat on that mission's agenda, after visiting and returning enormous amounts of data from Jupiter, Saturn and Uranus: the first close look at Neptune. O -j

YOLK PROTEIN PRODUCTION IN THE MARINE SHRIMP PENAEUS VANNAMEI

ABSTRACT Yolk production of the marine shrimp Penaeus vannamei was measured using an antibody to a subunit of the yolk protein complex. The effects of unilateral eyestalk ablation on protein synthesis of the hepatopancreas and ovary were measured in vitro. Initially, activity in both tissues increased; 21 days after eyestalk ablatior activity levels in both tissues returned to levels equal to or lower than preablation levels. The yolk protein content of the tissues increased shortly after eyestalk ablation and reached a maximum of 8% in ovarian tissue, but less than 1% in the hepatopancreas. Yolk proteins in the hemolymph were detected using an enzymelinked immunoassay. Both intact controls and eyestalk-ablated shrimp had as much as 1 mg/ ml yolk protein in the hemolymph during ovarian maturation. Newly released shrimp eggs had an average of 53 ng yolk protein per egg. Eyestalk ablation induced a rapid increase in protein synthesis in both ovary and hepatopancreas. During ovarian maturation, yolk proteins were transported through the hemolymph in this marine shrimp.

Foraging patterns of two syngnathid fishes: importance of harpacticoid copepods

The diets of juvenile (<g0 mm) Syngnathus scovelli and of H~ppocampus zosterae, abundant members of a resident fish community in a Thalassia testudnum seagrass bed in Tampa Bay, Florida, were examined from Apnl to October 1984. Harpacticoid copepods comprised most of the diet, both in terms of percent number and percent biomass, for the smaller size classes of S. scovelli and for H. zosterae, and harpacticoids generally had the highest index of relative importance (IRI) for both syngnathids. S. scovelli displayed ontogenetic switching to larger food items, such as amphipods. shrimp and crustacean eggs. Harpacticus sp. 1 was the most common harpacticoid copepod species found in the guts of the 2 syngnathids, but was only rarely encountered in prey samples from seagrass blades. Three other harpacticoids, Paradactylopodia brevicornis sp., Dactylopodia tisboides and Harpacticus sp. 2 had high IRIS in H. zosterae but not in S. scovelli. Vanderploeg & Scavia's selectivity index (E') was calculated for sampling dates when both species of syngnathids were most abundant, using prey density on seagrass blades as a measure of prey avadabhty. Only the harpacticoid Harpacticus sp. 1 had high positive selectivity values. MARINE ECOLOGY PROGRESS SERIES Mar. Ecol. Prog. Ser.