Investigations of carotenoids in some fauna of the Adriatic Sea. III. Leander (Palaemon) serratus and Nephrops norvegicus (Crustacea: Decapoda)

Investigations have been carried out on the carotenoids in Leander (Palaemon) serratus (Pennant) and Nephrops norvegicus (L.) (Crustacea: Decapoda) from the Adriatic Sea. The presence of the carotenoids was determined by means of columnar and thin-layer chromatography. The following carotenoids were found: Leander serratus: -carotene, echinenone, isocryptoxanthin, cryptoxanthin, canthaxanthin, lutein, isozeaxanthin, zeaxanthin, astaxanthin, and astacene; Nephrops norvegicus: -carotene, lutein, zeaxanthin, astaxanthin, and astacene.     

Variations du taux d'acide ascorbique au cours du développement de l'ovaire et du cycle d'intermue chez Palaemon serratus (Crustacea: Decapoda)

Variations in ascorbic acid content of the ovary, somatic tissues and the whole female body were studied during ovarian development and the molting cycle of Palaemon serratus. The conclusions are incomplete, due to insufficient data on the role of ascorbic acid in the physiology and metabolism of animals, and especially crustaceans. However, some results indicate that Vitamin C is accumulated in the female as the gonad index increases. Ascorbic acid is concentrated preferentially in the ovarian tissue. Some hypotheses are put forward relating to the role of ascorbic acid in the biosynthesis of chitin, steroid hormones, and in ovarian maturation.     

Variations de la teneur en acide ascorbique dans les oeufs de Cancer pagurus et Palaemon serratus (Crustacea: Decapoda) au cours de l'embryogenèse

Variations of ascorbic acid content were studied during different stages of embryogenesis in the two crustaceans Cancer pagurus and Palaemon serratus. Variations in the egg volume of P. serratus were also measured at each stage of embryogenesis. The eggs appeared able to synthesize ascorbic acid during the earlier embryonic stages. Ascorbic acid changes in the crustaceans' eggs are discussed in relation to the variations of proline, chitin, glycogen and glucose already studied. Ascorbic acid appears to play an important role in the survival of eggs incubating under unfavourable environmental conditions. Before hatching, the ascorbic acid content is as high as after spawning.     

Locomotor activity patterns and feeding habits in the prawn Palaemon xiphias (Crustacea: Decapoda: Palaemonidae) in Alfacs Bay,Ebro Delta (northwest Mediterranean)

Diel activity rhythms of the prawn Palaemon xiphias Risso, 1818 from Alfacs Bay, Ebro Delta, were studied by time-lapse videorecordings. Activity displayed an endogenous circadian rhythm, with maximum activity at night. Feeding habits were studied by frequency of occurrence and by the points method. The food of P. xiphias consisted mainly of crustaceans; the remains of amphipods, isopods, mysids, copepods, decapods and ostracods were identified. The remaining items consisted of molluscs, polychaetes, ophiuroids, plant material, sand, and unidentified organic debris. The results indicate that P. xiphias is a predator of benthic invertebrates rather than a scavenger or detritus feeder. Diet composition changes with increasing size of the prawn.     

R-cells and the digestive cycle in Penaeus semisulcatus (Crustacea: Decapoda)

Shrimp, Penaeus semisulcatus, were collected from Kuwaiti waters in 1980, and the R-cells in the hepatopancreas were observed during the digestive cycle. During the first 12 h they absorb soluble material from the lumen of the gland and, subsequently, they take-up soluble and particulate material from the haemolymph. Within the cytoplasm, apical and basal systems of smooth endoplasmic reticulum are concerned with these processes. Pinocytosis only occurs at the basal cell membrane. The absorbed material is stored as lipid and glycogen, and copper, sulphur and other elements are accumulated in a large dense vacuole. These activities are integrated with those of the other cell types to effect the assimilation of food in the hepatopancreas. A scheme is proposed which accounts for the main processes of digestion. The hepatopancreas governs the duration of the digestive cycle, which takes at least 24 h. Observations on the nature of intracellular storage and waste products could be used to assess the dietary requirements of artificially reared shrimp.     

Offshore spawning by the portunid crabScylla serrata (Crustacea: Decapoda)

The portunid crabScylla serrata (Forskål) is shown to migrate offshore to spawn. Records of 447S. serrata caught as bycatch by trawlers in the tropical waters of northern Australia were analysed with respect to area, depth, distance offshore and month of capture as well as the sex and size of the crabs and whether the females were ovigerous. The crabs were caught mainly in three areas that correspond to the tiger prawn trawl fishery, at between 10 and 60 m depth (mean 28.5 m), 3 to 95 km offshore (mean 17.9 km). Most (87%) of the crabs were captured in October and November, which suggests they move offshore in September and October. No crabs were reported from offshore by February. Over 97% of the crabs caught offshore were female, of these 61.5% were ovigerous. The size range of females (100–109 to 200–209 mm carapace-width size classes) and males (120–129 to 200–209 mm carapace-width size classes) caught was similar. The frequent occurrence in coastal waters of females that are larger than the modal size at spawning, as well as mature females with spent ovaries, suggests that many females return to the coast after spawning. Although some species of portunid crab are euryhaline, mature females of estuarine species migrate to the sea to spawn. The migration byS. serrata described here is far more extensive than would be required to reach sea water salinities; it probably provides a dispersal mechanism for larvae to enable the megalopa stage to recruit to habitats distant from those of the parents.     

Evidence for acclimation to hydrostatic pressure in Uca pugilator (Crustacea: Decapoda: Ocypodidae)

Groups of male Uca pugilator (Bosc) (Crustacea, Decapoda, Ocypodidae), acclimated to sublethal pressure (34 atm) subaqueously for 5 and 10 days, were observed subsequently at pressures up to 272 atm. Behavioral indicators of pressure resistance (“first response” and tetany) were employed to measure degrees of pressure acclimation in comparison with simultaneously and non-simultaneously conducted control experiments. No firm conclusions can be made on the basis of “first response” results, but the pressures required to induce tetany were significantly higher (P≤0.02, one-tailed comparison) in acclimated groups than in non-acclimated groups. These data and earlier studies by other investigators support the assertion that some shallow marine species are capable of at least limited short-term pressure acclimation.     

Reproduction and growth of the freshwater prawn, Palaemon paucidens (Decapoda: Palaemonidae) in a lake of Korea

This study analyzed the reproduction and growth of freshwater prawn, Palaemon paucidens De Haan 1844 from Suk-dang lake(Korea). The analysis of the sex ratio showed a higher proportion of males than that of females. The average size of the eggs was 6.12 (+/-0.55) mm3 in the non-eyed stage (stageA) and 7.20 (+/-0.86)mm3 in the eyed stage (stage B). The reproductive output (RO) calculated with the dried-body weight of an incubating female and the weight of the eggs in dried condition was 26.97% (n = 17) of the average females weight. Incubating prawn appeared in April, and the gonadosomatic indices(GSI) showed the highest value during three months from January to March. Based on the month when there was a high proportion of incubating females with a high GSI, the estimated spawning season of P. paucidens was April. The maturity of the female was evaluated by the development of the ovaries and the existence of eggs. The average body length when 50% of the females in the group reached maturity was 8.55 (+/-2.74) mm. The analysis of the length-frequency distribution showed that the life span of P. paucidens ranged from 12 to 13 months. Females mature faster than males.     

Physiological responses to fluctuation in temperature of salinity in invertebrates. Adaptations ofAlpheus viridari (Decapoda,Crustacea),Terebellides parva (Polychaeta) andGolfinigia cylindrata (Sipunculida) to the mangrove habitat

The snapping shrimpAlpheus viridari (Armstrong, 1949), the polychaeteTerebellides parva Solis-Weiss, Fauchald and Blankensteyn 1990, and the sipunculanGolfingia cylindrata (Keferstein, 1865) are commonly found in the same mangrove habitat, where they experience frequent, acute fluctuations in temperature and salinity. Ecological studies indicate a temporal variation, including occasional absence, in the distribution of bothG. cylindrata andT. parva; this fed us to examine the physiological adaptations of the three species (collected at Western Bay, Twin Cays, Belize in 1985, 1986 and 1988). Each was subjected to acute, repeated exposure to either control (35 S) and decreased (25 S) salinity or to control and increased (45 S) salinity. Ability to regulate water and ion content (g H₂O or mol g^-1 solute free dry wt) was examinedA. viridari behaved as a hyperosmotic conformer at decreased salinity but as an osmoconformer at increased salinity. Regardless of direction of salinity change,A. viridari regulated water content through change in Na⁺, K⁺, and Cl^– contents. In contrast,G. cylindrata behaved as an osmoconformer and did not demonstrate ability to regulate water content.T. parva behaved as an osmoconformer, showed incomplete regulation of water content via change in Na⁺, K⁺, and Cl^– contents but had limited survival following exposure to 45 S. Each species was also exposed to change in temperature. Species were subjected to acute, repeated exposure either to control (28°C) and decreased (21°C) temperature or to control and inereased (35°C) temperatureA. viridari regulated water and ion content under both experimental conditions. In contrast,T. parva did not regulate water and ion content under either experimental temperature.G. cylindrata did not regulate water and ion content during exposure to decreased temperature and did not survive exposure to increased temperature. ForA. viridari, weight specific oxygen uptake rates (mg O₂ g^-1 ash-free dry wt) were determined. Exposure to decreased salinity or to increased temperature resulted in a small sustained elevation in O₂ uptake. It is concluded that, unlikeA. viridari, T. parva andG. cylindrata are only marginally adapted to withstand the salinity and temperature stresses, respectively, of the mangrove habitat. The inability ofT. parva andG. cylindrata to fully adapt to extremes in the mangrove habitat could well explain the temporal variation seen in the distribution of these two species.Contribution number 380. Caribbean Coral Reef Ecosystems, National Museum of Natural History, Smithsonian Institution     

Larval settlement and metamorphosis in the sand crab Emerita talpoida (Crustacea: Decapoda: Anomura)

The effects of various potential cues on the survival and time to metamorphosis of larvae of the sand crab Emerita talpoida (Say) were examined. Zoeal duration, which ranged from 25 to 43 d, was not correlated with subsequent megalopal survival but had a weak, negative correlation with the duration of the megalopal stage. Neither food, sand nor water from containers with adults directly affected megalopal survival or duration. In a second experiment, the presence of sand both increased the probability of survival and shortened the duration of late zoeal stages. This is the first experimental evidence for delayed zoeal metamorphosis in a decapod. Settlement of E. talpoida appears to occur primarily during the zoeal phase, not at the megalopal stage.     

Functional cytology of the hepatopancreas of Penaeus semisulcatus (Crustacea: Decapoda) during the moult cycle

In the shrimp Penaeus semisulcatus, the digestive gland functions as the main site for the digestion, absorption and storage of nutrients and metals during the feeding stages of intermoult and for the mobilization of reserves during the non-feeding stages of pre-and post-moult. These different activities are reflected directly in the cytology of the gland. All the epithelial cells show marked fluctuations in frequency and changes in structure, form and function which occur in phase with the moult cycle. The shrimp were collected offshore from Kuwait in 1980.     

Action of eyestalks on the ovary in Rhithropanopeus harrisii and Crangon crangon (Crustacea: Decapoda)

The annual cycle of ovarian activity and eyestalk effects on the ovary in different phases of its activity were examined in the crab Rhithropanopeus harrisii Gould ssp. tridentatus Maitland, and the sand shrimp Crangon crangon L. In both species, the annual ovarian cycle consists of two phases of vitellogenesis and the resting phase. In R. harrisii, the eyestalks exert an inhibitory effect on vitellogenesis during the phase of vitellogenesis outside the breeding season, and are necessary for the process of oviposition during the breeding season. In C. crangon, ovary-inhibiting hormone is present in the eyestalks outside the breeding season, and has not been detected during this season. The resting phase of the ovary after the breeding season is caused by the ovary-inhibitiing hormone. Females of C. crangon are a suitable material for testing ovary-inhibiting hormone activity, while female R. harrisii are not.     

Patterns of trace-metal distribution in tissues of Pleoticus muelleri (Crustacea: Decapoda: Solenoceridae)

Trace-metal distribution in tissues of the shrimp Pleoticus muelleri Bate from the Patagonian region, Argentina, was related to sex, size and physiological condition. Concentrations of cadmium, copper, manganese and zinc were determined in the digestive gland, male reproductive system and muscle of adult specimens. Significant (p<0.01) sex-dependent differences in mean metal concentrations (g g^-1 wet wt) were found in the following tissues of males and females, respectively: digestive gland, Cu, 82.9 and 30.8; Zn, 32.5 and 44.9; reproductive system, Zn, 12.8 and 38.6; Mn, 1.7 and 3.1; Cd, 0.29 and 0.58. Metal levels of muscle showed no significant differences between sexes. Cadmium was not detected in muscle, suggesting that its incorporation into this tissue was strictly regulated. Metal concentrations in the male reproductive system were in general weakly correlated (0.001<p<0.05) with either body size or the concentration of metals in the digestive gland. The developing ovary incorporated substantial amounts of zinc, while cadmium and copper levels decreased at proportional rates (p<0.001). The patterns of the variations in the concentrations of these metals in the ovary strongly suggested that a regulatory mechanism operated throughout oogenesis. Manganese was not involved in this presumptive mechanism. The results of this study are discussed in terms of concentrations and in absolute amounts for standardized individuals.     

Allozyme and mitochondrial DNA variation in Cuban populations of the shrimp Farfantepenaeus notialis (Crustacea: Decapoda)

We investigated the genetic diversity among populations of the shrimp Farfantepenaeus notialis, the most abundant penaeid species around Cuba. A total of 25 allozyme loci were analyzed in samples of shrimps from seven localities at the south central platform of the island (Ana María Gulf). Samples from three of these localities and from Batabanó Gulf and Guacanayabo Gulf at the south west and south east platforms of the island, respectively, were also characterized at the mtDNA level through sequence variation of a 2027 bp segment including part of the COI and COIII genes. Of the 25 allozyme loci studied 9 were polymorphic: Akp2, Akp3, AmyB, Est3, Gdh, GP7, and Per1, 2 and 3. In contrast to mtDNA, the pattern of allozyme variation among localities revealed strong population structuring at Ana María Gulf, with significant F _st in all pairwise comparisons. The magnitude of F _st estimates as well as the grouping pattern obtained by a UPGMA analysis based on a distance matrix indicated that the level of differentiation was concordant with the geographical position of the localities and the hydrographic regime. Homogeneity of mtDNA suggested that differentiation of allozyme loci might be due to more recent events rather than historical isolation of the sampled populations. Ana María and Guacanayabo Gulf populations were differentiated by mtDNA from Batabanó Gulf, at the southwestern end of the island. The analysis showed three restriction site differences among them, suggesting genetic isolation of the two regions. The present results also suggest that an artificial introduction of larvae from Tunas de Zaza into Batabanó Gulf, in an effort to repopulate this fishing region, may have been ineffective. Received: 13 December 1999 / Accepted: 2 October 2000     

Effect of hypophyseal gonadotropins (FSH and LH) on the ovaries of the sand shrimp Crangon crangon (Crustacea: Decapoda)

The effect of purified preparations of ovine hypophyseal gonadotropins NIH-FSH-S12 and NIH-LH-S19 on the histological structure of the ovaries of the sand shrimp Crangon crangon (L.) (Crustacea: Decapoda) was studied. All experiments were carried out on sexually mature females, out of the breeding season. The individuals treated with the gonadotropins included intact females as well as those in which the eyestalks were ligated to eliminate a source of gonad-inhibiting hormone (GIH). The results obtained indicate that both FSH and LH have a stimulating effect on the ovaries of the common shrimp, FSH causing growth in the number of somatic cells of the ovary, and LH — meiosis in the sex cells. The effect of each of the 2 gonadotropins was similar in intact and eyestalkless females which indicates its independence from the presence or absence of GIH. The response of crustacean ovaries to mammalian FSH and LH indicates that gonadotropins may act upon invertebrates.     

Metabolic adaptation of Zostera marina (eelgrass) to diurnal periods of root anoxia

The temperate seagrass Zostera marina L. is common in coastal marine habitats characterized by the presence of reducing sediments. The roots of this seagrass grow in these anoxic sediments, yet eelgrass is highly productive. Through photosynthesis-dependent oxygen transport from leaves to roots, aerobic respiration is supported in eelgrass roots only during daylight; consequently, roots are subjected to diurnal periods of anoxia. Under anoxic root conditions, the amino acids alanine and -amino butyric acid accumulate within a few hours to account for 70% of the total amino acid pool, while glutamate and glutamine decline. Little ethanol is produced, and the pool size of the organic acid malate changes little or declines slowly. Upon the resumption of shoot photosynthesis and oxygen transport to the roots, the accumulated -amino butyric acid declines rapidly, glutamate and glutamine pools increase, and alanine declines over a 16-h period. These adaptive metabolic responses by eelgrass to diurnal root anoxia must contribute to the successful exploitation of shallow-water marine sediments that have excluded nearly all vascular plant groups. A metabolic scheme is presented that accounts for the observed changes in organic and amino acid pool sizes in response to anoxia.     

Patterns of bioaccumulation of an essential trace element (zinc) and a pollutant metal (cadmium) in larvae of the prawn Palaemon serratus

Palaemon serratus Pennant larvae from females caught near Roscoff (France) or the Bay of Biscay in 1983, were reared in the laboratory. From hatching to the first stage after metamorphosis, the larvae were exposed to zinc and cadmium introduced separately or together into the rearing medium. At the end of experimental contamination, the concentrations of the two metals in the organisms were determined. The level of zinc in organisms was mainly independent of its concentration in the water, suggesting that the bioaccumulation of this essential trace element is controlled by some physiological process. The accumulation of cadmium in the larvae paralleled the overloads of this metal in the water. Increased zinc concentrations in water have little or no effect on the cadmium levels in organisms. The most important interaction between these two metals is an antagonism exerted by cadmium on the biological uptake of zinc.     

Settlement cues in successive developmental stages of the ghost shrimps Callichirus major and C. islagrande (Crustacea: Decapoda: Thalassinidea)

Larvae of Callichirus major (Say) and C. islagrande (Schmitt) were given unconditioned water with sand, water conditioned by previous exposure to adults (AW) without sand, or the combination of both AW and sand to determine if these factors served as settlement cues. Shrimp were first given stimuli upon reaching the last zoeal stage (ZIV), the decapodid stage (D), or the first juvenile stage (J1). Once initiated, exposure of shrimp to stimuli was maintained until termination of␣the experiment. Stage duration, burrowing activity of decapodids and early juveniles and location of exuviae were observed daily. Exposure to sand and AW did not decrease duration of the decapodid stage in either species. However duration of ZIV in C. major appeared to decrease when these stimuli were offered at this stage; this suggests that molting to Stage D may be delayed without such cues. When stimuli were examined separately, AW was found to have a significant effect on the duration of ZIV, while the effect of sand with unconditioned water and effects of simultaneously offered stimuli were not significant. Shrimp that received stimuli at ZIV subsequently burrowed more at D and J1 than individuals that did not receive stimuli at ZIV. Location of exuviae was recorded as on top of sand (not burrowed during molt) or within sand (burrowed during molt) for each shrimp's molt from Stages D to J1 (D molt), and from J1 to J2 (J1 molt). In C. major, the percentage of D exuviae and J1 exuviae found within sand as opposed to on top of sand was significantly higher in individuals which received stimuli at ZIV than for those that first received them at D or J1. When stimuli were examined separately in C. major, the effect of sand on burrowing activity was highly significant, while AW and the stimuli in combination had weaker effects. For C. major, AW appeared to accelerate development to D, while sand triggered settlement. Neither stimulus altered stage duration or burrowing activity of C. islagrande. Received: 7 December 1997 / Accepted: 24 July 1998