Allocation of organic material and energy to the holdfast,stipe, and fronds inPostelsia palmaeformis (Phaeophyta: Laminariales) on the California coast

Postelsia palmaeformis were collected from the lower intertidal at Pigeon Point, California, USA, in May 1987, and the proximate composition and allocation of energy to the various body components were determined. The holdfast and stipe have a proximate composition (% dry weight) of ca. 40% ash, 5.3% protein, 1% lipid, 2% soluble carbohydrate, and 55% insoluble carbohydrate. The fronds have a proximate composition of ca. 25% ash, 6.5% protein, 2% lipid, 3% soluble carbohydrate, and 65% insoluble carbohydrate. The energetic level was ca. 12 kJ g^-1 dry wt and ca. 19 kJ g^-1 ash-free dry wt. The relative proportion of three plant components varied, comprising 26, 39, and 35% wet wt and 20, 42, and 38% kJ for the holdfast, stipe, and fronds, respectively. A plant with a basal stipe diameter of 33 mm contains 114 g wet wt and 266 kJ. The maximal density found in May 1987 was 826 plants, 49 301 g wet wt, and 106 157 kJ m^-2.P. palmaeformis differs in these characteristics from another intertidal pheophyte,Durvillaea antarctica, that is found in a high-energy intertidal zone.     

Investigation of the relationship between invertebrate predation and biochemical composition,energy content,spicule armament and toxicity of benthic sponges at McMurdo Sound,Antarctica

The biochemical and energetic composition, spicule content, and toxicity of benthic sponges was investigated in McMurdo Sound, Antarctica from October through December 1984. The predominant organic constituent of sponges was soluble and insoluble protein. Levels of total protein ranged from 17.0 to 55.9% dr. wt. Levels of lipid and carbohydrate were low, ranging from 2.1 to 9.6 and 0.6 to 3.5% dr. wt, respectively. Levels of ash were high and variable (32 t0 79% dr. wt), reflecting species-specific differences in spicule contents. Calculated energy contents of sponges were low, with a mean of 9.8±3.5 kJ g^-1 dr. wt; ranging from 5.1 kJ g^-1 dr. wt in Sphaerotylus antarcticus to 17.4 kJ g^-1 dr. wt in Dendrilla membranosa. Insoluble protein accounted for the greatest contribution to the energetic composition of the sponges, while lipid and carbohydrate combined contributed to less than 25% of the overall energy. Normalized spicule volumes of sponges ranged from 0.15 to 0.38 cm³ g^-1 dr. wt. Ichthyotoxicity assays indicated that 9 (56%) of 16 antarctic sponge species were toxic. The most highly toxic species were Mycale acerata and Leucetta leptorhapsis. The high incidence of toxicity in antarctic sponges indicates that the current hypothesis suggesting a simple inverse relationship between toxicity and latitude in marine sponges is invalid. There was little correspondence between the energetic composition or spicule contents of the sponges and feeding patterns (electivity indices) of sponge-eating predators. Although the asteroid Perknaster fuscus antarcticus specializes on the highly toxic, fast-growing M. acerata, most antarctic sponge-eating predators appear to be generalists which feed on the more abundant, non- to mildly-toxic, sponge species. This feeding strategy is based on exploitation of low energy, sedentary prey, which require a minimal energy output to harvest.     

Biochemical and energetic composition of bathyal echinoids and an asteroid,holothuroid and crinoid from the Bahamas

The biochemical and energetic composition of body components of ten species of bathyal echinoids, and an asteroid, a holothuroid and a stalked crinoid were determined from individuals sampled from a variety of deep-water sites near the Bahamas (north Caribbean Sea) in October 1988. When compared with other studies of echinoderms, no geographic- or depth-related differences in biochemical or energetic composition were found. Body-wall tissues were composed primarily of skeletal material (mineral ash), but were comparatively high in organic material in the echinothuriid echinoids, and the asteroid and holothuroid. Gut tissues and pyloric cecae had high levels of lipid and protein, indicating their potential role in nutrient storage. Body-wall tissues were generally low in energy, but were highest in the echinoidsAraeosoma belli (7.7 kJ g^–1 dry wt) andSperosoma antillense (8.0 kJ g^–1 dry wt), the asteroidOphidiaster alexandri (8.9 kJ g^–1 dry wt), and the holothuroidEostichopus regalis (13.1 kJ g^–1 dry wt). Energy levels of gut and pyloric cecal tissues were two to three times higher than those of body-wall tissues. Total somatic tissue energy values varied greatly among species, ranging from 1.5 kJ in the echinoidAspidodiadema jacobyi to 142.1 kJ inE. regalis. As the bathyal echinoderms examined in this study occur in great abundance, they represent a significant reservoir of organic and inorganic materials and energy in deep-water benthic systems.     

Energy substrates for eggs and prefeeding larvae of the dolphinCoryphaena hippurus

Changes in the chemical composition of developing dolphin (Coryphaena hippurus) eggs and prefeeding yolksac larvae were determined in order to estimate probable dietary requirements of first-feeding larvae. Daily dry matter, protein nitrogen (PN), non-protein nitrogen (NPN), lipid, gross energy content, fatty acid and amino acid profiles from Day 1 to Day 2 eggs and Day 1 to Day 3 larvae were compared. Lipid was the primary endogenous energy source accounting for the daily caloric deficit through both the egg and larval stages, except over the day of hatching. The catabolism of lipid by embryos (0.078 cal d^–1) was greater than that by yolksac larvae (0.036 cal d^–1). The higher demand for energy by embryos was related to a greater rate of protein synthesis during the egg stage. The ratio of PN:NPN increased during egg development without change in total nitrogen content, but was constant throughout the yolksac larvae period. The lipid content per embryo did not decrease over the hatching period (Day 2 to 3, postspawning). However, there was a loss in amino acid content not totally accounted for by sloughing of the chorion at hatching. This loss, as protein, accounted for 0.053 cal of gross energy, which represented 70% of the total estimated energy needs of the fish over this period. Loss of non-essential amino acids (25%) was higher than that of essential amino acids (13%). Proline and tyrosine accounted for 32% of the total loss of amino acids at this time. The only preferential use of fatty acids over any period was a small but significant drop in the content of C22:6n-3 prior to the onset of feeding (Day 5, postspawning). It is speculated that the pattern of energy-substrate use of first-feeding dolphin larvae will reflect the pattern of endogenous energy use during the egg and prefeeding yolksac larval stages. Diets or feeding regimens with lipid as the primary energy source, and containing a fatty acid profile similar to that of eggs or yolksac larvae, should be useful in culturing this species, at least during the early feeding stages.     

Lipid classes and their content of n-3 highly unsaturated fatty acids (HUFA) in Artemia franciscana after hatching, HUFA-enrichment and subsequent starvation

The distribution of n-3 highly unsaturated fatty acids (HUFA) over the major neutral and polar lipid classes was determined for two predominant types of live food used in the larviculture of marine fish and shrimp, i.e. freshly hatched and HUFA-enriched Artemia, and compared with data reported in the literature for wild copepods, representing the natural diet of these larvae. Lipid class composition and their content of n-3 HUFA, particularly eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), were assessed in freshly hatched, HUFA-enriched and subsequently starved Artemia franciscana. The n-3 HUFA enrichment was based on feeding Artemia a lipid emulsion in which either fatty acid ethyl esters (EE, diluted with olive oil) or triacylglycerol (TAG) provided a level of 30% n-3 HUFA. Enrichment of Artemia with either type of the lipid emulsions resulted in an increase of total lipid content from 20.0 to 28.2–28.7% of dry matter mainly due to the accumulation of neutral lipid, primarily TAG (from 82 to 158 mg g⁻¹ dry wt in freshly hatched and 24-h enriched Artemia). Enriched brine shrimp utilized up to 27–30% of their TAG content during 72 h of starvation at 12 °C. The absolute tissue concentrations of polar lipids remained constant at 71 to 79 mg g⁻¹ dry wt throughout the enrichment and subsequent starvation. The level of n-3 HUFA increased drastically during enrichment from 6.3% of total fatty acids (8.2 mg g⁻¹ dry wt) in freshly hatched nauplii to between 20.4 and 21.8% (40.4 to 43.2 mg g⁻¹ dry wt) in 24-h enriched Artemia and was not significantly affected by the source of n-3 HUFA. During starvation, 18:0, 20:4n-6 and 20:5n-3 were retained, whereas 18:4n-3, 22:5n-3 and 22:6n-3 were specifically catabolized. The major polar lipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), of freshly hatched Artemia showed very low levels of DHA (<0.1% of total fatty acids) and carried about 45% of the total EPA present. Enrichment with either of the emulsions resulted in an increase of the neutral lipid fraction which concentrated >64% of the EPA and >91% of the total DHA present. This is in sharp contrast with the high levels of n-3 HUFA, in particular DHA, in the polar lipid fraction reported for wild copepods. The contrasting distribution of DHA in the neutral and polar lipid fractions of enriched brine shrimp compared to the natural diet may influence the efficacy of this essential fatty acid for marine fish larvae in aquaculture systems. Received: 10 June 1997 / Accepted: 8 August 1997     

Effect of sexual maturation on the tissue biochemical composition of<Emphasis Type="Italic"> Octopus vulgaris</Emphasis> and<Emphasis Type="Italic"> O</Emphasis>.<Emphasis Type="Italic"> defilippi</Emphasis> (Mollusca: Cephalopoda)

Changes in the protein, lipid, glycogen, cholesterol and energy contents, total amino acid and fatty acid profiles of Octopus vulgaris and O. defilippi tissues (gonad, digestive gland and muscle) during sexual maturation (spermatogenesis and oogenesis) were investigated. Both species showed an increase of amino acids and protein content in the gonad throughout sexual maturation (namely in oogenesis), but allocation of these nitrogen compounds from the digestive gland and muscle was not evident. The major essential amino acids in the three tissues were leucine, lysine and arginine. The major non-essential amino acids were glutamic acid, aspartic acid and alanine. With respect to carbon compounds, a significant increasing trend (P<0.05) in the lipid and fatty acid contents in the three tissues was observed, and, consequently, there was also little evidence of accumulated lipid storage reserves being used for egg production. It seems that for egg production both Octopus species use energy directly from food, rather than from stored products. This direct acquisition model contrasts with the previous model for Octopus vulgaris proposed by ODor and Wells (1978: J Exp Biol 77:15–31). Most of saturated fatty acid content of the three tissues was presented as 16:0 and 18:0, monounsaturated fatty acid content as 18:1 and 20:1 and polyunsaturated fatty acid content as arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3). Though cholesterol is an important precursor of steroid hormones, this sterol content exhibited variations that do not seem to be related with the maturation process. Moreover, significant differences (P<0.05) were obtained between genders, suggesting that perhaps there is a greater physiological demand for cholesterol during spermatogenesis than oogenesis. If the component sterols of octopus are of a dietary origin, considerable variation in the cholesterol content between species might be expected on the basis of the sterol composition of their prey. The glycogen reserves increased significantly in the gonad and decreased significantly (P<0.05) in the digestive gland and muscle of O. vulgaris (these trends were not evident in O. defilippi). Glycogen may play an important role in the maturation process and embryogenesis of these organisms, because carbohydrates are precursors of metabolic intermediates in the production of energy. It was evident that sexual maturation had a significant effect upon the gonad energy content, but the non-significant energy variation (P>0.05) in the digestive gland and muscle revealed no evidence that storage reserves are transferred from tissue to tissue. The biochemical composition of digestive gland and muscle may not be influenced by sexual maturation, but rather by other biotic factors, such as feeding activity, food availability, spawning and brooding.Communicated by S.A. Poulet, Roscoff     

Maternal allocation of lipid classes and fatty acids with seasonal egg production in Atlantic cod (Gadus morhua) of wild origin

A suite of characteristics is often used to assess egg quality as these properties potentially play important roles in progeny survival and growth. Our objective was to assess egg characteristics including lipid biocomposition of an iteroparous, batch-spawning teleost of wild origin. Maternal allocation to egg number was generally dome-shaped (5 of 8 females) and egg size declined over the breeding season for eight breeding pairs of wild Atlantic cod (Gadus morhua) (n = 43 batches). Egg lipid composition ranged considerably among females and between egg batches within females (e.g., phospholipids 40–86 %; polar 47–87 % and neutral lipids 15–52 % of total lipids; polyunsaturated fatty acids 16–50 % of total fatty acids). Principal component analyses revealed significant inter-relationships among maternal traits, batch sequence and fecundity, and egg size and composition. Seasonal trends with regard to lipid deposition were variable; three females showed consistent declines in lipid parameters (μg egg⁻¹) with both batch number and egg diameter, one female showed consistent increase and the four remaining females showed no trend. The three females that exhibited seasonal declines in egg lipid content were characterized as having high fertilization success (>75 %). Our findings highlight the variability in lipid allocation to eggs of batch spawners of wild origin and characterize the composition of endogenous reserves available during embryogenesis and yolk sac larval stages.     

Organic and calorific content of the body tissues of deep-sea elasipodid holothurians in the northeast Atlantic Ocean

Data are presented on the biochemical analysis of protein, lipid, carbohydrate and ash for the ovary, testis, gut and body wall of six species of elasipodid holothurians at a variety of stations in the Porcupine Seabight and Abyssal Plain (northeast Atlantic Ocean). Samples were collected between 1980 and 1982. The species investigated were Benthogone rosea, Laetmogone violacea, Oneirophanta mutabilis, Deima validum, Benthodytes sordida and Psychropotes longicauda. Lipid was the dominant soluble constituent of the ovary and protein was dominant in the testis. Tissue calorific content was determined from the biochemical data and by microbomb calorimetry. The ovaries had higher calorific values than the other body tissues when determined by both methods. Comparison of the two methods suggests that the calorific values for testis, gut and body wall are significantly different, and this may be a function of the calcium-carbonate content of these tissues. Total-body calorific value varied from 24.26 J mg^-1 ash-free dry weight (AFDW) (5 799 cal g^-1 AFDW) to 25.43 J mg^-1 AFDW (6 078 cal g^-1 AFDW). Total holothurian-body calorific biomass at depths of 1 010, 2 000 and 4 000 m is 0.49, 3.69, and 0.25 kJ m^-2 (118, 882, 59.4 cal m^-2), respectively. Holothurians form a significant store of energy in the deep sea.     

Amino and fatty acid dynamics of<Emphasis Type="Italic"> Lysmata seticaudata</Emphasis> (Decapoda: Hippolytidae) embryos during early and late reproductive season

The present study investigates amino and fatty acid dynamics of embryos of different-sized simultaneous hermaphrodite shrimp (SH) (Lysmata seticaudata) during early (ERS) and late reproductive seasons (LRS). A significant relative decrease in total amino acids and essential amino acids (EAA) was recorded (P<0.05) during the development of embryos produced by shrimp collected during ERS and LRS. The content of non-essential amino acids (NEAA) showed a smaller variation, without a marked decrease. During the last embryonic stage, the major EAAs of embryos were, in decreasing magnitude, lysine and arginine, while the major NEAAs were glutamic acid and valine. A substantial decrease in lipid content (P<0.05) was observed, and the quantitatively more important fatty acids were the saturates 16:0 and 18:0, the monounsaturates 18:1n-9 and 18:1n-7 and the polyunsaturates 20:4n-6 (arachidonic acid, ARA), 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic acid, DHA). Monounsaturates were used at a higher rate, and embryos produced by SH shrimp displayed similar consumption rates of saturated and polyunsaturated fatty acids. Considering individual fatty acids, no clear utilization pattern between different-sized SH shrimp in ERS and LRS was recorded. The inexistence of consistent differences between amino and fatty acid utilization during embryogenesis among different-sized SH shrimp in ERS and LRS emphasizes the variability affecting offspring in decapod crustaceans.Communicated by S.A. Poulet, Roscoff     

Biochemical composition,energy content and chemical antifeedant and antifoulant defenses of the colonial Antarctic ascidian<Emphasis Type="Italic"> Distaplia cylindrica</Emphasis>

The colonial ascidian Distaplia cylindrica occurs both as scattered individual colonies or in gardens of colonies in fine-grained soft substrata below 20 m depths off Anvers Island along the Antarctic Peninsula. Individual colonies, shaped as tall rod-like cylinders and anchored in the sediments by a bulbous base, may measure up to 7 m in height. D. cylindrica represent a considerable source of materials and energy for prospective predators, as well as potential surface area for fouling organisms. Nonetheless, qualitative in situ observations provided no evidence of predation by sympatric predators such as abundant sea stars, nor obvious biofouling of colony surfaces. Mean energy content of whole-colony tissue of D. cylindrica was relatively high for an ascidian (14.7 kJ g^–1 dry wt), with most of this energy attributable to protein (12.7 kJ g^–1 dry wt). The sympatric omnivorous sea star Odontaster validus consistently rejected pieces of D. cylindrica colonies in laboratory feeding assays, while readily ingesting similarly sized alginate food pellets. Feeding deterrence was determined to be attributable to defensive chemistry, as colonies of D. cylindrica are nutritionally attractive and lack physical protection (conspicuous skeletal elements or a tough outer tunic), and O. validus display significant feeding-deterrent responses to alginate food pellets containing tissue-level concentrations of organic extracts. In addition, high acidity measured on outer colony surfaces (pH 1.5) as well as homogenized whole-colony tissues (pH 2.5) are indicative of surface sequestration of inorganic acids. Agar food pellets prepared at tissue levels of acidity resulted in significant feeding deterrence in sea stars. Thus, both inorganic acids and secondary metabolites contribute to chemical feeding defenses. D. cylindrica also possesses potent antifoulant secondary metabolites. Tissue-level concentrations of hydrophilic and lipophilic extracts caused significant mortality in a sympatric pennate diatom. Chemical feeding deterrents and antifoulants are likely to contribute to the abundance of D. cylindrica and, in turn, play a role in regulating energy transfer and community structure in benthic marine environments surrounding Antarctica.Communicated by P.W. Sammarco, Chauvin     

Group size and foraging efficiency in yellow baboons

Summary I studied the foraging behaviour of adults in three different-sized groups of yellow baboons (Papio cynocephalus) at Amboseli National Park in Kenya to assess the relationship between group size and foraging efficiency in this species. Study groups ranged in size from 8 to 44 members; within each group, I collected feeding data for the dominant adult male, the highest ranking pregnant female, and the highest ranking female with a young infant. There were no significant differences between groups during the study in either the mean estimated energy value of the food ingested per day for each individual (385±27 kJ kg^-1 day^-1) or in the estimated energy expended to obtain that food (114±3 kJ kg^-1 day^-1). Mean foraging efficiency ratios, which reflect net energy gain per unit of foraging time, also did not vary as a function of the size of the group in which the baboons were living. There was substantial variation between days in the efficiency ratios of all animals; this was the result of large differences in energy intake rather than in the energy expended during foraging itself. The members of the smallest group spent on the average only one-half as much time feeding each day as did individuals in the two larger groups. However, they obtained almost as much energy while foraging, primarily because their rate of food intake while actually eating tended to be higher than the rate in the other groups. The baboons in the small group were observed closer to trees that they could climb to escape ground predators, and they also were more likely to sit in locations elevated above the ground while resting. Such differences would be expected if the members of the small group were less able to detect approaching predators than individuals that lived in the larger groups. The results of this study suggest that predator detection or avoidance, rather than increased foraging efficiency, may be the primary benefit of living in larger groups in this population.     

Changes in biochemical and fatty acid composition of the razor clam <Emphasis Type="Italic">Solen marginatus</Emphasis> (Solenidae: Bivalvia) during larval development

Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported in this species.     

Rate of heat dissipation by gametes and larval stages of Mytilus edulis

Heat dissipation of sperm, eggs and various stages of the planktonic larvae of the mussel Mytilus edulis L. was recorded directly at 15°C. The absolute heat dissipation increased steadily over all stages examined. The massspecific heat dissipation also increased during early embryogenesis from the fertilized egg to the D-larval stage. Starting from the early veliconcha stage, however, the mass-specific rate of heat dissipation declined from about 90 m W g^-1 with increasing body size with a weight exponent of-0.35. A comparison with literature data revealed a consistently higher metabolic activity than previously estimated by indirect calorimetry for gametes and larvae.     

Fatty-acid composition of ovulated eggs from wild and cultured turbot (Scophthalmus maximus) in relation to yolk and oil globule lipids

The fatty-acid composition of lipids from ovulated eggs of wild and cultured turbot was investigated in order to estimate the nutritional requirements during embryonic and early larval development. Lipid comprised 13.8±0.5% (n=5) and 13.2±0.7% (n=7) of the egg dry weight in wild and cultured turbot, respectively. Polyunsaturated fatty acids (PUFA) of the (n-3) series accounted for 39% of total fatty acids in total lipid of both wild and cultured fish. The predominant (n-3) FUFA was docosahexaenoic acid (22:6 n-3), which also was the most abundant fatty acid in turbot eggs and comprised 24 and 23% of the total egg fatty acids in wild and cultured fish, respectively. Phospholipids, triacylglycerols and cholesterol-wax esters of turbot eggs all exhibited a specific fatty-acid profile distinctly different from that of total lipid. The general pattern of the fatty-acid distribution in lipids of eggs from wild and cultured turbot was similar, but the relative amount of 18:2(n-6) was considerably higher and 20:1(n-9) slightly higher in cultured fish. These differences were extended to all lipid classes and probably reflect the dietary intake of certain vegetable and marine fish oils. Calculations based on light microscopical studies showed that 55 to 60% of the total lipids in cultured turbot eggs are confined to the oil globule. The size of the oil globule remained constant during embryogenesis, and a reduction in size occurred first after hatching and mainly after yolk depletion. This implies that the total amount of lipids utilised during the embryonic development is considerably less than the total lipids present in ovulated turbot eggs. Comparison of the fatty-acid composition of total lipids from eggs and vitellogenin of wild turbot reveals that egg lipids contained a lower level of saturated and a higher level of monounsaturated fatty acids. Eggs also contained wax esters, which were not detected in vitellogenin, suggesting that vitellogenin is not the only source of lipids for turbot eggs.     

Fecundity,brood loss and egg development through embryogenesis of <Emphasis Type="Italic">Armases cinereum</Emphasis> (Decapoda: Grapsidae)

The present work is a comprehensive study of reproduction and embryonic development of Armases cinereum. Ovigerous A. cinereum (Bosc, 1802) females from Sebastian Inlet, Florida (9.88–19.4 mm CW) lay 2,000–12,000 eggs per brood, depending on their CW (mm): fecundity = 24.662 CW^1.9432. A. cinereum displayed significant brood loss through development (ca. 500 eggs per brood) independently from their CW (no senescence). However, since smaller females lay fewer eggs than larger ones, the percentage of eggs lost during embryonic development is greater in smaller females. The number of eggs carried on a later stage of development (potential fertility = 5.5593 CW^2.4417) is a more accurate estimate of the reproductive output and subsequent recruitment. Egg volume increased during development (64%, 0.025–0.041 mm³ or 0.36–0.43 mm of diameter, N = 270) and was strongly correlated with egg water content increase (19.21%, r = 0.89). Lipids, particularly fatty acids, seem to be the major energy source for embryonic development, decreasing 56.31 and 37.08% (respectively) during embryonic development; both are negatively correlated with egg volume (r = −0.90). The utilization of fatty acids through the different developmental stages of A. cinereum is presented. The most consumed fatty acids are the monounsatured (43.33 μg mg⁻¹ dw), followed by the saturated (29.91 μg mg⁻¹ dw) and polyunsaturated (24.03 μg mg⁻¹). Palmitic (16:0) and linoleic (18:2n-6) acids are preferentially consumed (19.5 and 17.9 μg mg⁻¹ dw, respectively). The high proportion of essential polyunsaturated fatty acids of C₁₈ and C₂₀ reflects the consumption of primary producers such as mangrove leaves. EPA/DHA ratio (2.85–3.84) and low DHA content indicated that this species appears in a medium-low level of the trophic chain. The low ratio of 18:1n-7/18:1n-9 and high percentage of 18:1n-9 (marker of carnivory) may be a sign of the consumption of juvenile invertebrates. The high percentage of odd-numbered FA indicated the occurrence of detritivores/scavenger behaviours. The fatty acid composition of the eggs reflects adult feeding ecology (omnivorous) and habitat.     

Biochemical composition of the deep-sea red crab Chaceon quinquedens (Geryonidae): organic reserves of developing embryos and adults

Deep-sea red crabs Chaceon quinquedens (Smith) were collected in traps at depths of 860 and 1043 m in the northern Gulf of Mexico. Ovigerous crabs were maintained in the laboratory and the developing embryos were sampled every 2 wk until hatching. Proximate analysis (lipid, protein, carbohydrate, and ash) of embryos was performed to determine patterns and rates of organic reserve utilization during embryogenesis. Midgut gland, gonads, and clutch (as appropriate) of adult crabs (males, non-ovigerous females and ovigerous females) were analyzed for the same components as the embryos. Red crab embryos exhibited different patterns of yolk deposition and subsequent depletion of yolk components during embryogenesis. There was a range of lipid to protein (L:P) ratios among the different clutches examined, indicating plasticity in the relative proportions of lipid and protein yolk. The energy used for embryogenesis was estimated by converting the amounts of lipid, protein and carbohydrate in the embryos to their caloric equivalents; final values, taken from 9 mo-old embryos whose siblings were hatching as zoeae, were subtracted from the initial values of sibling embryos sampled at the time of collection (2 to 3 mo old). The amount of energy consumed during embryogenesis in the laboratory was relatively constant (0.12 to 0.13 cal egg^-1). There was considerable variability among the concentrations of organic reserves in the midgut gland of adult crabs and in the ovaries of females. Variations in midgut gland L:P ratios and ovaries were related to the reproductive status of the females, but there were no trends related to depth of capture.     

Annual biomass and production of the oceanic copepod community off Discovery Bay,Jamaica

Monthly samples were collected in oceanic waters off Discovery Bay, Jamaica, in 60- and 200-m vertical hauls, using 200- and 64-m mesh plankton nets, from June 1989 to July 1991. Length-weight regressions were derived for twelve genera of copepods (R²=0.79 to 0.97). For eight occasions spanning the study period, biomass estimates generated from these length-weight regressions differed by only 3% from direct weight determinations. The mean ash content of copepods was 7.1%, and the energy density was 20.8 kJ g^-1 ash-free dry weight (AFDW). Mean annual biomass of the total copepod community in the upper 60 m was 1.83 mg AFDW m^-3 (range 1.14 to 2.89 mg AFDW m^-3), and for the 200-m water column was 0.96 mg AFDW m^-3 (range 0.12 to 1.99 mg AFDW m^-3). Estimates of generation times for five common taxa ranged from 16.1 to 33.4 d. None of the taxa investigated displayed isochronal development; in general, stage duration increased in later copepodite stages. Weight increments showed a significant decrease in later copepodite stages, but with strong reversal of the trend from stage 5 to adult female in most species. Daily specific growth rates also declined in later copepodite stages, and ranged from 1.49 d^-1 in stage 1–2 Paracalanus/Clausocalanus spp. to 0.04 in stage 5-female of Oithona plumifera. Progressive food limitation of somatic copepodite growth and egg production is postulated. Naupliar production was 50.4 to 59.5% of copepodite production, and egg production was 35.1 to 27.7% of copepodite production in the 60-and 200-m water columns, respectively. Total annual copepod production, including copepodites, nauplii, eggs and exuviae, was 160 kJ m^-2 yr^-1 for the upper 60 m and 304 kJ m^-2 yr^-1 for the upper 200 m. Secondary production of the copepod community in oceanic waters off Discovery Bay approaches 50% of the corresponding value in tropical neritic waters.     

Growth and content of energy reserves in juvenile sea scallops,Placopecten magellanicus,as a function of swimming frequency and water temperature in the laboratory

The effects of swimming frequency and water temperature on shell growth, tissue mass, and stored energy reserves of juvenile sea scallops, Placopecten magellanicus Gmelin, were examined in a factorial laboratory experiment spanning six weeks in July and August 1992. Individually tagged scallops of similar initial size (22.5±0.1 mm shell height, n=240) were induced to swim to exhaustion at three different swimming frequencies (every day, twice a week, or not at all) in two different water temperature regimes (4 to 7 or 7 to 13°C). The scallops were fed an ad libitum mixture of cultured microalgae. At the end of the experiment, cumulative increase in shell height, dry weight of soft tissues, condition index of dry adductor muscle (adductor muscle dry weight/soft tissue dry weight x 100) and total carbohydrate content of dry adductor muscle were measured for each scallop. Scallops at the higher temperature had significantly greater shell heights, and were in better metabolic condition as evidenced by significantly higher condition indices and muscle carbohydrate contents. The dry soft tissue weights did not differ significantly from their low temperature counterparts. Swimming frequency had no significant effect on shell height, dry tissue weight, or carbohydrate content, but condition index of the adductor muscle increased significantly with swimming frequency. These results show that not only was there no cumulative cost of swimming in terms of shell growth, total soft tissue weight, or carbohydrate content in young scallops, but that condition of adductor muscle tissue was higher in scallops that swam.     

Role of biochemical energy reserves in the metamorphosis and early juvenile development of the oyster Ostrea chilensis

Metamorphosis in the Chilean oyster Ostrea chilensis was complete 36 h after release of the larvae, when 100% of the individuals showed edge growth of the dissoconch. The size of the larval shell did not change during metamorphosis, although the total dry weight of the larva decreased considerably. During this period, when the gill ciliature was undeveloped and the oyster therefore unable to feed, energy demands were met by biochemical reserves retained from the larval phase. Proteins contributed the largest quantity of energy to the metamorphosing oyster, 69.3% of the total expended, whereas lipids supplied 24.3% and carbohydrates only 6.4%. The process of metamorphosis consumed 64.5% of the energy reserves held by the pediveliger at the time of release. When metamorphosis was complete, growth began and tissue reserves were replenished, protein and carbohydrate accumulating rapidly early in the juvenile stage. Received: 26 December 1997 / Accepted: 8 July 1998     

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.