Reproductive biology of the common shrimp Crangon crangon (Decapoda: Crangonidae) in the central Irish Sea

Aspects of the reproductive biology of the common shrimp Crangon crangon (L.) were studied in Port Erin Bay, Isle of Man, Irish Sea. Size at sexual maturity was determined from the proportions of ovigerous females and of females with maturing ovaries. The size at which 50% of females are mature is estimated (±95% confidence intervals) as 12.5±0.48 mm carapace length. Based on the proportions of ovigerous females and of mature females, the main breeding season was from January to June. Mean ovarian dry weights indicated two broods (winter and summer), with females bearing winter broods (WB) having higher gonad indices than those with summer broods (SB). WB females with non-eyed eggs and with eyed eggs differed in the regression of ovarian dry weight on carapace length, indicating preparation for laying a second brood. In both broods the moult stages of berried females were related to egg stage. Moulting will occur following the release of the brood. During embryonic development, mean egg length and egg volume were larger in all stages, and the mean dry weight of individual eggs of all stages heavier, in WB than in SB; there was no difference in egg number, however. Consequently, reproductive investment, the proportion of female weight devoted to egg production, was 67% higher in WB (0.20±0.04) than in SB (0.12±0.03). There is a significant effect of egg volume on brood weight, but not on egg number. In both broods, egg number was a negatively allometric function of female body size in non-eyed eggs and an isometric function of female body size in eyed eggs. Brood mortality during incubation was higher in SB (17%) than WB (10%). Differences in the reproductive variables and investment between the two broods of C. crangon are discussed in the light of reproductive strategies and life history.Communicated by J.P. Thorpe, Port Erin     

Studies of the pigments in the shrimp Crangon crangon (Crustacea: Malacostraca)

The material examined consisted of adult specimens (male and female) of the shrimp Crangon crangon (L.) collected during the summer of 1967 from the Gdask Bay of the Baltic Sea. Column and thin-layer chromatography was used for the separation of the carotenoids. The ester compounds and protein complexes of carotenoids were hydrolized with 15% KOH in methanol at room temperature in a nitrogen atmosphere for 48 h. The absorption maxima of the various fractions and spots were determined on the spectrophotometer Specol after eluation. The identification of the carotenoids was based mainly on the absorption maxima in appropriate organic solvents and on the R_t values. The acetone extract from the Crangon crangon specimens gave a light blue fluorescence and absorption maxima at wavelengths of 447, 463, 595 to 596 and 667 m. The following carotenoids were found to be present in the adult specimens of Crangon crangon: -carotene, cantaxanthin, astaxanthin, free and esterified lutein, zeaxanthin, and a form of xanthophyll which was not precisely identified. In addition to the above, biliary dyes were also found, probably of the mesobiliviolin and mesobilirhodin type.     

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.     

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.     

Reproduction of the estuarine mysid Taphromysis bowmani (Crustacea: Malacostraca) in fresh water

We have monitored the incorporation of ³H-glycine into, and the excretion of, soluble tissue and extrapallial fluid proteins in the hardshell clam Mercenaria mercenaria in an attempt to follow some of the metabolic events that occur antecedent to shell deposition. After incubating at 20°C for 48 h, clams were killed and the distribution of incorporated and unincorporated tritium in seawater, mantle fluid, hemocoelic-tissue fluid, extrapallial fluid and tissue was determined. Most of the incorporated tritium was in the insoluble tissue proteins. Much more incorporated tritium was found in the hemocoelic-tissue fluid fraction than in the extrapallial fluid. We assume that most of the radioactivity we followed was due to free or incorporated radioactive glycine. The ratio of ³H-protein to ³H-glycine was greater in the extrapallial fluid than in the hemocoelic-tissue fluid, suggesting either protein secretion into or glycine removal from the extrapallium. We also observed that both ³H-protein and ³H-glycine concentrations were higher in the mantle fluid than in the external sea water, although the ratios of ³H-glycine to ³H-protein in these two fluids were not different.     

Strong maternal effects and extreme heterogeneity of progeny development in the caridean shrimp Sclerocrangon boreas (Crangonidae)

Sclerocrangon boreas is uncommon among marine coastal carideans in having a non-dispersing, abbreviated (2-stage) larval phase. We investigated the implications of this strategy in terms of fecundity, offspring provisioning and brood care in S. boreas from the St. Lawrence Gulf and Estuary in 2009–2010. Fecundity scaled positively to female body size but was low due to the production of large, lipid-rich eggs. Offspring size at all stages of development was positively related to female size. Larval traits and lipid dynamics indicate obligatory lecithotrophic development from hatching to juvenile. The larva becomes a juvenile on the mother and remains associated with her for sometime after. The co-occurrence of early egg stages among many juveniles in some clutches raises the possibility that maternal care of juveniles includes the provisioning of trophic eggs or eggs reclaimed from other females.     

Temperature tolerance of the estuarine prawn Upogebia africana (Anomura,Crustacea)

Continuous temperature measurements were made in a typical South East African estuary. Mean summer (November to March) temperatures were in the range 19° to 24°C, and in winter (June to August) from 13° to 16°C. Large daily temperature fluctuations of 6° to 10°C occurred in summer; these appear to result from tidal movement of cool sea water into the estuary. In winter, temperature fluctuations were much smaller (3° to 5°C). The burrowing prawn Upogebia africana (Obtmann) was found to have an upper lethal temperature of 29°C in both winter and summer. The resistance time of prawns to temperatures above 30°C was much greater in summer than in winter. It was possible to acclimate winter prawns and increase their resistance time to a level comparable to that of summer individuals. A latent period of 40 h occurred before acclimation effects were detectable. Long-term exposure of prawns to high temperatures did not increase their resistance above that of summer prawns. Water at a temperature above this upper lethal temperature is not pumped through the burrows. This avoidance behaviour considerably increases the ability of U. africana to withstand short-lived temperature extremes.     

An unusual abbreviated larval life in the estuarine burrowing prawn Callianassa kraussi (Crustacea: Decapoda: Thalassinidea)

The larval stages of Callianassa kraussi Stebb. were previously unknown. Larvae were bred out in the laboratory and found to be incapable of swimming. There are two larval stages, lasting 3 to 5 days in sea water of 34 to 35 S at 20 °C. Observations under simulated field conditions in the laboratory, and in the field—where burrow casts were made using a polyester resin, indicated that the larvae metamorphose to the first post-larval stage in the parent burrow, and then burrow directly into the wall of the parent burrow.     

A new method to determine in situ growth rates of decapod shrimp: a case study with brown shrimp Crangon crangon

Shrimps are economically and ecologically very important, yet a lack of ageing techniques and hence unknown growth rates often impairs analytical assessments and management. A new method for the determination of in situ growth rates of shrimps is presented, based on dry weight condition. Since this index oscillates from low values directly after moult to highest values prior to moult in constantly feeding shrimp, the lowest observed pre-moult condition followed by a moult was introduced as a reference value to separate growing and starving individuals in field data. Experiments with Crangon crangon confirmed that (1) post-moult condition varies in a narrow physiologically optimal range, regardless of recent growth increments, and (2) dry weight condition prior to moult is closely related to the subsequent length increment. The method was applied to estimate growth increments from in situ dry weight condition data of C. crangon. The new method can easily be applied to other related species, since the required data can be obtained from very simple short-term experiments.     

Anaerobic metabolism in the shrimp Crangon crangon exposed to hypoxia,anoxia and hydrogen sulfide

The brown shrimp Crangon crangon was collected in the Penzé estuary, Bretagne, in April 1994 and exposed to hypoxia, anoxia and combinations of hypoxia and sulfide. Exposure to sulfide induced total anaerobic metabolism even at an oxygen saturation which would otherwise permit totally aerobic metabolism. In addition to preventing aerobic metabolism there was a direct toxic effect of sulfide. Haemocyanin oxygen affinity (p₅₀) values from non-stressed C. crangon were relatively low. The p₅₀ values all exceed those where environmentally induced lactate accumulation occurs. It seems unlikely that lactate is an affinity modulating factor under environmental hypoxia.     

Study by evolution of nucleic acid content of prepuberal growth in the shrimp Crangon vulgaris

Growth of the shrimp Crangon vulgaris was studied by following the evolution of its nucleic acid concentration and total content. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) analysis were effected on homogenates of whole shrimps. Cell multiplication was estimated from evolution of total DNA content, and cell size increment from evolution of fresh weight: DNA ratio. DNA puric bases ratio and RNA monoribonucleotides percentages were constant throughout the investigation period. A decrease in DNA concentration was observed from 50 to 20 M/g dry defatted weight (DDP), when fresh weight increases from 40 to 570 mg. This decrease was more marked in the first half of the period studied (prepuberal phase). The DNA content in the whole shrimp increases with fresh weight without slowing down at sexual maturity. However, at the beginning of the prepuberal phase the cell-multiplication rate seems to be graduated rather than continuous; this is still to be explained. Cell size, calculated from fresh weight: DNA ratio, increases until the shrimp weighs 300 mg; beyond this weight, cell increment proceeds much more slowly. The weight gain of shrimps throughout the growth period studied is mainly attributable to hyperplasia — which occurs constantly — while hypertrophy insures only 21% weight increment in the largest shrimps. As protein content, RNA content is a linear function of shrimp weight. RNA:DNA ratio evolution is similar to that of cell size and protein content. We suggest that cells have attained a physiological balance when shrimps reach a weight of 300 mg.     

Spermiogenesis and sperm structure in the shrimp Parapenaeus longirostris (Crustacea: Dendrobranchiata): comparative aspects among decapods

Early spermatids of the dendrobranchiate shrimp Parapenaeus longirostris (Lucas, 1846) have a spherical nucleus with large patches of heterochromatin, surrounded by a cytoplasmic mass that contains the conspicuous proacrosomal vesicle. The highly polarized mid spermatid mainly consists of the nuclear region, displaying a discontinuous nuclear envelope, and a large proacrosomal vesicle located at the opposite side of the cell. The most recent spermiogenic transformations primarily concern elongation of the proacrosomal vesicle to form a tapering spike. This results in the typically tack-shaped sperm of natantian decapods. The initial steps of spermiogenesis in the two studied dendrobranchiates prove to be parallel to reptant spermiogenesis in some respects, namely rupture of the nuclear envelope, chromatin decondensation and differentiation of electron-dense regions within the proacrosomal vesicle content. Specifically, whereas the anteriormost condensation gives rise to the operculum in brachyurans, in dendrobranchiates it becomes the apical portion of the spike. Despite an unquestionable morphological similarity between the sperm of carideans and dendrobranchiates, spermiogenesis in both groups displays meaningful differences. Spermatids of caridean shrimps lack a distinct proacrosomal vesicle. In the course of spermiogenesis, the spike arises from aggregated cytosolic materials; hence it is not membrane-bound. Unlike in other decapods, caridean sperm do not undergo a conventional acrosome reaction, since exocytotic events are not involved in this process. The above arguments suggest that, in the Decapoda, separation into three sperm classes is more suitable than the two traditionally accepted classes. The dendrobranchiate and reptant sperm types share a number of spermiogenic and functional features, while the caridean sperm type appears to represent an independent evolutive line with regard to sperm development and function.     

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     

Ammonia excretion of Artemia sp. (crustacea: Branchiopoda) under axenic conditions)

Ammonia excretion of the Utah strain of Artemia sp. grown in axenic culture media was followed throughout the different stages of larval development. The ammonia accumulated in the culture medium does not affect ammonia excretion rates under our laboratory conditions. Growth rate, density and starvation all affect ammonia excretion. Ammonia excretion is directly related to the numerical growth index and inversely related to Artemia sp. density. Starved adult Artemia sp. excrete considerably lower amounts of ammonia than brine shrimp grown in nutritive medium. In view of the difficulties often encountered in estimating the excretion rates of small crustaceans, our culture conditions would appear advantageous for further studies on the purine metabolism of Artemia sp.     

Respiratory responses of the estuarine mysid Neomysis integer (Peracarida: Mysidacea) in relation to a variable environment

The euryhaline mysid Neomysis integer (Peracarida: Mysidacea) is a common member of the hyperbenthos of the upper reaches of European estuaries. In the East Looe River Estuary (Cornwall, England), this species experiences extensive tidal and seasonal changes in temperature (3 to 15 °C) and salinity (1 to 34‰). In this investigation, the effects of temperature (5, 10 and 15 °C) and salinity (1, 10, 20 and 30‰) on the oxygen consumption of male and female N. integer are reported, and are related to field measurements to identify the adaptive responses of the respiratory physiology to such a variable environment. The general responses were similar for each sex; however, at any given temperature/salinity combination, male N. integer consumed more oxygen than females. The general trends were increased oxygen consumption with increasing temperature (Q₁₀ values ranged from ∼1.7 to 2.5) and decreased oxygen consumption with increasing salinity. Temperature and salinity interacted at high water antagonistically to minimise changes in mysid oxygen-consumption. When related to tidal fluctuations in temperature and salinity experienced by N. integer inhabiting the East Looe River Estuary, the results reveal how the respiratory physiology of this species is adapted to its variable environment. Received: 16 June 1998 / Accepted: 15 December 1998     

Simultaneous hermaphroditism in the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae): an undescribed sexual system in the decapod Crustacea

Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,” individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species. Received: 26 October 1997 / Accepted: 21 April 1998     

Antifouling adaptations of marine shrimp (Crustacea: Decapoda: Caridea): Functional morphology and adaptive significance of antennular preening by the third maxillipeds

Preening (cleaning, grooming) of the antennules and other cephalothoracic appendages by the third maxillipeds was observed in several species of shrimp. Distribution and ultrastructure of serrate grooming setae on the third maxillipeds, which scrape the antennules, was studied with light and scanning electron microscopy. The motor patterns of antennular cleaning were similar for all species. Antennular preening was the most frequent grooming behavior observed, but the duration of other grooming behaviors was greater. Tidepool shrimps (Heptacarpus pictus) experimentally prevented from grooming the antennules by ablation suffered fouling of the olfactory hairs of the antennules with their subsequent breakage and loss; antennules of controls remained clean and undamaged. Antennular preening, a frequent and widespread behavior of caridean shrimps and other decapod crustaceans, is suggested as having high adaptive value in keeping sensory sites free of epizoic and sedimentary fouling which might render them inoperative.     

Vertical distribution and nocturnal migration of Nyctiphanes couchi (Crustacea: Euphausiacea) in relation to the summer thermocline in the Celtic Sea

Vertical distributions and nocturnal migrations of the developmental stages of Nyctiphanes couchi (Bell) in relation to the summer thermocline in the Celtic Sea, 25 to 26 August 1982, have been investigated using the Longhurst-Hardy Plankton Recorder (LHPR). The vertical distributions of the metanauplii and adult females suggest that N. couchi liberates its young within the euphotic zone as mature metanauplii which, in a matter of hours, moult into the first feeding stage (Calyptopis I). The ascent migration by adult females took a maximum of 3 h (17.10 to 20.05 hrs) and had an amplitude of 50m (54 to 4 m) from below to above the thermocline. A 7C° thermocline occurred between 20 to 30 m in these profiles. The nocturnal migrations by the females were for the purpose of breeding as well as feeding within the euphotic zone and were not influenced by the presence of the thermocline. The majority of the calyptopes and furciliae remained above the thermocline over the sampling period. The post-larval males and females migrated; their vertical distributions showed a pattern similar to those of the adult females. The larger the developmental stage, the deeper was the mode of its vertical distribution. The zooplankton dry weight in the profiles ranged from 3.74 to 6.91 g per haul (=1.85 to 3.45 g C m^-2, 0 to 100 m). The euphausiids represented 35% of total zooplankton dry weight and their migrations removed a large percentage of the total zooplankton biomass from the euphotic zone for 18 h d^-1. Such a large displacement of biomass would have a major impact on the biological interactions within the ecosystem.     

Distribution of deep-water gorgonian corals in relation to benthic habitat features in the Northeast Channel (Atlantic Canada)

The distribution and abundance of deep-water gorgonian corals were investigated along 52 transects at 183–498 m depth in the Northeast Channel, between Georges Bank and Browns Bank in the northwest Atlantic, using a remotely operated vehicle and a towed video-camera system. Three species (Paragorgia arborea, Primnoa resedaeformis, and Acanthogorgia armata) were observed. Primnoa occurred on 35 transects below 196 m depth, with highest local abundance in stands of 104 colonies per 100 m². Paragorgia was present on 21 transects deeper than 235 m, with highest local abundance of 49 colonies per 100 m². Acanthogorgia was observed at only four transects between 231 m and 364 m, with a local maximum abundance of 199 colonies per 100 m². The maximum abundance averaged for whole transects was 19.2 and 6.2 colonies per 100 m² for Primnoa and Paragorgia, respectively. The corals were more common in the outer part of the channel along the shelf break and slope than on the shelf in the inner part. All three species showed a patchy distribution with no signs of competitive exclusion at any spatial scale. Transects with high abundance of corals were characterised by depths greater than 400 m, maximum temperatures less than 9.2°C, and a relatively high percentage coverage of cobble and boulder (more than 19% and 6%, respectively). High temperatures probably control the upper depth limit of the corals, and Primnoa seems to tolerate slightly higher temperatures than Paragorgia. Abundance of both species was negatively correlated with average temperature and positively with cobbles. Together, temperature, percentage cobble and salinity accounted for 38% of the variance of Primnoa. The comparable figure for Paragorgia was 15%. The observed distribution indicated that the abundance of coral is controlled by additional factors such as larger-scaled topographic features governing the current regimes and thus also the supply of food and larvae.Communicated by R. J. Thompson, St. Johns     

Age determination in the Antarctic shrimp Notocrangon antarcticus (Crustacea: Decapoda), using the autofluorescent pigment lipofuscin

Determination of basic population parameters in long-lived Crustacea is hindered by a lack of appropriate methods for age determination. This study uses the pigment lipofuscin as an age marker in the common Antarctic decapod Notocrangon antarcticus (Pfeffer, 1887) from the eastern Weddell Sea. Resin brain sections of the lateral somacluster of the olfactory lobe of 189 specimens were digitally recorded by confocal microscopy and images were subsequently analyzed. A modal progression analysis of the lipofuscin concentration–frequency distribution revealed a total of eight regularly spaced modes presumed to reflect consecutive annual age classes. All eight modes contained females, and the first four contained males. No regular modes were obvious in the comparable length-frequency distribution. The average yearly pigment accumulation was nearly linear and estimated as 0.02% area fraction year⁻¹, which is considerably lower than rates published for species from lower latitudes. This is probably explained by the effect of low water temperature on metabolism and lipofuscin accumulation rate. The growth parameters CL_∞ and k from the von Bertalanffy growth function were 22.3 mm and 0.79 year⁻¹ for females, respectively, and 16.9 mm and 0.64 year⁻¹ for males, respectively. Mortality, estimated from catch curves, amounted to 0.44 year⁻¹ in females and 0.92 year⁻¹ in males, whereas P/B, calculated from the mass specific growth rate method, was slightly lower. The results indicate that the lipofuscin-inferred population parameters are an improvement over what can be learned about N. antarcticus with traditional methods. Received: 1 August 2000 / Accepted: 21 September 2000