Seasonal changes in tissue weight and biochemical composition for the bivalve Donax trunculus L. on the Algerian coast

Seasonal changes in the body weight and composition of the bivalve Donax trunculus L. from Azur Plage near Algiers, Algeria, were studied during the period September 1971-June 1974. Percentage dry tissue weight was minimal in October–December and rose to reach a peak in spring or summer, the rise corresponding with rapid maturation of the gonads. Decrease in tissue weight in the autumn also coincided with a rapid decline maturity of the gonads between August and October. Lipid content increased with sexual maturity, while carbohydrate content was greatest in the autumn and declined to a seasonal minimum in April–May. The changes are compared with those for D. trunculus in other Mediterranean populations, and for D. vittatus (da Costa) elsewhere in Europe.     

Variation of the physiological energetics of the bivalve Spisula subtruncata (da Costa, 1778) within an annual cycle

Spisula subtruncata is an infaunal filter-feeding bivalve, which lives in shallow sandy bottoms (2-20 m depth) from Norway to the Atlantic coasts of Morocco, including the Mediterranean Sea. Considering that fisheries of this species have become an important economic resource in some European countries (e.g. The Netherlands), it is of great interest to know the seasonal variation in its physiological energetics. For this purpose, individuals of S. subtruncata were collected and maintained under ambient temperature and seawater conditions of Dutch coastal waters. Physiological processes related to the acquisition and utilisation of energy (e.g. clearance rate [CR], absorption and oxygen uptake) were measured under ambient conditions of the period March 1999 to February 2000. Mean annual clearance and respiration rates (RR) were 0.99 l h⁻¹ and 0.23 ml O₂ h⁻¹ for a standard individual of 250 mg. Values for both clearance and respiration rate were high during spring and summer and low during autumn and winter. Stepwise multiple regression analyses indicated a significant relationship of the clearance rate with temperature and particulate organic matter (POM), whereas respiration rate was significantly related to temperature, absorption rate (AR) of the animals and their reproductive condition. Absorption efficiency (AE) of the food was significantly related to food quality. Scope for growth (SFG) of S. subtruncata, as well as flesh weight of the animals, was high in summer and low in winter.     

Structure of seasonal migrations of the littoral hermit crab Clibanarius vittatus (Bosc)

A seasonal migration in the hermit crab Clibanarius vittatus (Bosc) is described and its structure examined for size-related or sexual differences that might lead to differential mortalities. The largest crabs, which were nearly all males, began to leave the shore in early summer, but the smaller females stayed until late autumn. The smaller crabs also returned to the shore at least one month in advance of the large crabs in the spring. No size-related or sexual differences were found in the abilities of the crabs to regulate their volumes when moved from 34.5%. to 10.5%. salinity which is the observed salinity range in their usual habitat.     

Population study of Astarte sulcata, da Costa, 1778, (Mollusca,Bivalvia) from two Norwegian fjords based on the fatty acid composition of the adductor muscle

Multivariate analyses of fatty acid composition of Astarte sulcata, collected in Northwest Norway in October 2005, showed significant differences between geographically close populations. This biochemical heterogeneity may have been caused by high genetic drift due to the direct development of the species. The results indicate that deep basins may provide an alternative bathymetric guide for spreading of offspring rather than being carried on currents crossing such basins. Thus, the combination of biology and topography might have led to the observed pattern that populations from opposite sides of a fjord are biochemically more distant than populations along the same side of a fjord/basin.     

Respiratory and osmoregulatory responses of the hermit crab, Clibanarius vittatus (Bosc), to salinity changes

Intertidal hermit crabs were stepwise acclimated to 10, 20, and 30‰ salinity (S) and 21 ± 1 °C. Hemolymph osmolality, sodium, chloride, and magnesium were isosmotic (isoionic) to ambient sea water at 30‰ and hyperosmotic (hyperionic) at 20 and 10‰ S, while hemolymph potassium was significantly hyperionic in all acclimation salinities. Total body water did not differ significantly at any acclimation salinity. Oxygen uptake rates were higher in summer-than winter-adapted crabs. No salinity effect on oxygen consumption occurred in winter-adapted individuals. Summer-adapted, 30‰ acclimated crabs had a significantly lower oxygen consumption rate than those acclimated 10 and 20‰ S. Crabs exposed to 30 10 30‰ and 10 30 10‰ semidiurnal (12 h) and diurnal (24.8 h) fluctuating salinity regimes showed variable osmoregulatory and respiratory responses. Hemolymph osmolality followed the osmolality of the fluctuating ambient sea water in all cases, but was regulated hyperosmotically. Hemolymph sodium, chloride, and magnesium concentrations were similar to hemolymph osmolality changes. Sodium levels fluctuated the least. Hemolymph potassium was regulated hyperionically during all fluctuation patters, but corresponded to sea water potassium only under diurnal conditions. The osmoregulatory ability of Clibanarius vittatus (Bosc) resembles that reported for several euryhaline brachyuran species. The time course of normalized oxygen consumption rate changed inversely with salinity under semidiurnal and diurnal 10 30 10‰ S fluctuations. Patterns of 30 10 30‰ S cycles had no effect on oxygen consumption rate time course changes. The average hourly oxygen consumption rates during both semidiurnal fluctuations were significantly lower than respective control rates, but no statistical difference was observed under diurnal conditions.     

Leaf essential oil composition of 10 species of Ocotea (Lauraceae) from Monteverde,Costa Rica

The leaf essential oils of 10 species of Ocotea (Lauraceae) from Monteverde, Costa Rica (Ocotea floribunda, Ocotea holdridgeana, Ocotea meziana, Ocotea sinuata, Ocotea tonduzii, Ocotea valeriana, Ocotea veraguensis, Ocotea whitei, and two undescribed species, Ocotea new species “los llanos”, and Ocotea new species “small leaf”) have been obtained by hydrodistillation and analyzed by GC–MS in order to discern the differences and similarities between the volatile chemical compositions of these species. The principal common constituents of the 10 species of Ocotea were α-pinene, β-pinene, β-caryophyllene, and germacrene-D.     

Polymorphism and selective predation in Donax faba Gmelin (Bivalvia: Tellinacea)

Donax faba Gmelin is abundant in the upper intertidal zone on wave-beaten sandy beaches throughout East Africa. It maintains a feeding position within the wash zone by migrating up and down the beach with the tide. The species is highly polymorphic for shell colour; 14 morphs are present in the population studied. During migration, D. faba is preyed upon by a crab Ocypode ceratophthalmus (Pallas) and a wading bird, Crocethia alba (Pallas). Predation by the crab is shown to be non-random with respect to morph. The commonest morph, which has a disruptive colouration, is more heavily predated when the population density is low and a non-cryptic, rarer morph when density is high. Selection is therefore stabilizing (or directional) at high density and apostatic at low density. The polymorphism is shown to be stable over the period of the investigation (one year).     

Studies on wound healing,and an estimation of the rate of regeneration,of the siphon of Scrobicularia plana (da Costa)

Wound closure of the siphon of Scrobicularia plana (da Costa), after amputation of the tip, is complete within 48 h. Once the lesion has been plugged by connective tissue new epithelial tissue begins to grow and is fully formed 96 h after wounding. As the epithelial cells are being formed, regeneration of the siphon commences at a rate of ≈ 6 mg per wk. When expressed in terms of percentage weight increase of the total siphon weight (20%) this rate is comparable with that calculated for other bivalves. The siphon continues to grow until the original size is attained. When small amounts of siphon are removed (15% of total siphon), regeneration is of little energetic cost, even when animals are starved. When greater amounts are, however, removed from unfed animals (e.g. 50% of the total siphon) regeneration takes place at the expense of the body condition, the animal using 0.6 kJ of body energy to replace 0.2 kJ of siphon.     

Distribution and population dynamics of the limpet Patella aspera (Lamarck) in Bantry Bay

The population ecology of Patella aspera (Lamarck) was studied as part of an oil pollution baseline study. Contrary to earlier reports, P. aspera appears to be a protandrous hermaphrodite. Maturation of the gonads began in May-June and spawning took place in October. Variations in density, standing crop, and mean size were related to exposure to wave action and tidal level. The low shore in extreme exposure may be designated as the centre of P. aspera's range; abundance is high but biomass and mean size are reduced. Higher on the shore, and in reduced exposure to wave action, P. aspera attains a greater mean size and biomass, but is eventually replaced by P. vulgata L. Two main factors are adduced as being critical to competition between the two species. In terms of tidal level, P. aspera is less tolerant of desiccation than P. vulgata, while in terms of the exposure-shelter gradient, P. aspera appears to have a much less variable growth rate. P. aspera may be defined, therefore, as a non-migratory, low shore, specialist species, highly adapted to a specific set of environmental conditions, but lacking the ability to adapt to others.     

Studies in the bivalve, Tellina tenuis Da Costa. IV. Further experiments in enriched sea water

Tellina tennis Da Costa was kept for four months in four large outdoor tanks containing sand and sea water. There was a 10 % daily exchange of sea water, pumped directly from the sea. Three tanks received daily addition of nutrients in the form of sodium nitrate and sodium dihydrogen phosphate, giving enrichment of approximately 3, 10, and 30 times natural sea-water levels of nitrate in the different tanks. Phosphate, nitrate, chlorophyll, and organic carbon in the water were measured regularly, the nitrate by Autoanalyser. Water temperature and solar radiation were recorded. Zooplankton samples were taken daily and Tellina were sampled monthly for length, weight, and biochemical analysis of tissues.Phosphate was always present in excess. The lowest level of nitrogen enrichment resulted in almost complete utilisation of nitrate, with a significant increase of organic carbon and chlorophyll above control levels. Zooplankton occurred in the greatest numbers in this tank, and Tellina showed the best survival, growth, and condition. In the tanks with the higher levels of enrichment, excess nutrients led to growth of macrophytic algae on the surface and sides of tank. This had an adverse effect on the phytoplankton production: zooplankton numbers were lower, as was growth of Tellina.     

The biochemical composition of krill, Euphausia superba Dana,from South Georgia

Krill, Euphausia superba Dana, sampled from waters around South Georgia in 1978 contained 10–11% protein, 2–6% lipid, 0.3–0.6% carbohydrate, 2% chitin, and 3–4% mineral ash (all mean values, % fresh weight).Lipid content varied greatly with sexual maturity: males contained 2–4% lipid, immature animals 4% (both increasing to 5–6% later in the season) and mature females 5–6% (although some contained as much as 9%). Gravid females lost ≈60% of their lipid at spawning, and a biochemical estimate of fecundity gave values in the range 7000 to 15 000.The major lipid classes were phospholipid, triacylglyceropl, and free sterol, and there was 1–2% wax ester. The mean pigment content was 21.5 μg/g fresh weight. Triacylglycerol fatty acids were low in polyenoic acids and contained up to 4% phytanic acid; compositions were variable and showed the probable influence of dietary input. Phospholipids were rich in polyenoic acids, especially 20 : 5ω3 and 22 : 6ω3, and usually had 18 : 1ω7 > 18 : 1ω9. Ovarian triacylglycerol contained almost no polyenoic acids, but ovarian phospholipid was fairly unsaturated.These results are discussed in relation to the Antarctic environment, and compared with the results of previous work on caridean decapods.     

Phenolic composition and its seasonal variation in Calluna vulgaris

Major phenolic compounds in the shoots of Calluna vulgaris were chlorogenic acid, the 3-O-glucoside, 3-O-galactoside and 3-O-arabinosid     

Seasonal changes in flesh weight and biochemical composition of mussels (Mytilus edulis L.) in the Conwy Estuary,North Wales

Sublittoral Mytilus edulis L. from natural mussel beds of the Conwy Estuary fishery exhibited an annual cycle of dry flesh weight, biochemical composition, and caloric value during 1971–1974.Mean percentage values of the main components of dry flesh, with seasonal extremes in parentheses, were: protein 58.7 (46.4–73.1), carbohydrates 22.5 (4.1–36.7), lipids 7.0 (3.9–9.6), and ash 11.8 (8.8–17.2). The mean caloric values of dry flesh were 5.57 kcal/g ash-free and 4.92 kcal/g ashinclusive.Individual dry flesh weight was highest in summer and autumn, when protein and carbohydrate were maximal, and decreased through the winter to a post-spawning minimum in spring. Weight loss in winter resulted from rapid utilization of carbohydrate (glycogen) reserves and a depletion of both protein and lipid content. It is considered likely that mussels were then stressed by food shortage at the time when metabolic demands, due to gametogenesis, were highest.During the six main fishing months, October to March, the average weight of dry flesh fell by 30–50 % and caloric content by 35–45 %. The likelihood of similar losses in cultivated mussel stocks is indicated and the need for comparable information in fishery management is emphasized. The extent to which predators compensate for these seasonal changes in prey quality also requires examination.     

Larval release behaviors of the striped hermit crab, Clibanarius vittatus (Bosc): Temporal pattern in hatching

Ovigerous hermit crabs, Clibanarius vittatus (Bosc), were examined in the laboratory to (1) determine if the time of larval release is a synchronous event, (2) determine the influence of a damaged gastropod shell during the egg hatching process, and (3) describe larval release behaviors. Ovigerous hermit crabs from natural light:dark (LD) and tidal cycles were moved to constant conditions 2-3 days prior to the predicted time of larval release. Larval release was synchronous, occurring near the time of expected sunset. Females with early-stage embryos placed under constant conditions displayed a free-running circadian rhythm, suggesting that the rhythm is under endogenous control. Hermit crabs with early-stage embryos that were placed under a shifted LD cycle (advanced 12 h relative to the ambient photoperiod) before being placed under constant conditions advanced their larval release rhythm by 12 h, indicating the rhythm can be entrained by the LD cycle. Hermit crabs with an intact shell released larvae in bursts at sunset over several consecutive nights (period = 24.2 h). In contrast, hermit crabs with damaged shells released larvae at different times over the course of a single day. Ovigerous females with intact shells exhibit several stereotypical hatching behaviors. The female stands on her walking legs and thrusts her abdomen, moving the shell in an oscillating motion. This movement may assist in breaking the outer membrane of the egg case. The female generates a water current inside the shell with her scaphognathite and mouthparts, which transports the newly hatched larvae out of the shell. Females in damaged shells did not display these behaviors; instead, larval release was a prolonged event with little movement of the female, and often the newly hatched larvae were not viable. These results indicate that an intact shell plays an important role in the hatching process for this hermit crab.     

Feeding behavior and differential absorption of biochemical components by the infaunal bivalve Mulinia edulis and the epibenthic Mytilus chilensis in response to changes in food regimes

We measured changes in the feeding rate and food absorption efficiency of two suspension feeding bivalves, cross-trasplanted between habitats with special emphasis on their capacity for differential absorption of biochemical components from their food supply. Mulinia edulis were moved from the intertidal zone to the subtidal zone, and Mytilus chilensis from the subtidal to the intertidal zone for a period of 7 days, and then compared with animal that had not been transplanted. Experimentally prepared diets similar to those available in the two different environments were offered to the bivalves, and their rates of feeding and differential uptake of biochemical components were determined and statistically compared. The two species did not achieve complete acclimation of their feeding behaviour during the transplant period since the highest ingestion rates for biochemical components occurred under dietary conditions that reflected their habitats of origin. Absorption efficiency showed greater acclimation than the other physiological parameters measured, indicating the capacity of these species to modulate their enzymatic-digestive activity depending on food composition. We conclude that both Mytilus and Mulinia have a certain degree of physiological plasticity in their feeding behaviour and assimilatory balance of biochemical components, being greater in Mytilus. When both species encounter ambient food conditions characteristic of their normal habitats, they show maximum values of food absorption, while under conditions where their typical diets are exchanged (Mytilus in intertidal and Mulinia in subtidal), the energy absorbed declines in each, but in ways very different between the two species. Thus, Mytilus exposed to high concentrations of low quality seston reduced the energy absorbed by 31.7% compared to its normal habitat, while Mulinia exposed to low concentrations of high-quality food reduced their energy absorption by 64%.     

Bacterial Communities from Shoreline Environments (Costa da Morte,Northwestern Spain) Affected by the Prestige Oil Spill

The bacterial communities in two different shoreline matrices, rocks and sand, from the Costa da Morte, northwestern Spain, were investigated 12 months after being affected by the Prestige oil spill. Culture-based and culture-independent approaches were used to compare the bacterial diversity present in these environments with that at a nonoiled site. A long-term effect of fuel on the microbial communities in the oiled sand and rock was suggested by the higher proportion of alkane and polyaromatic hydrocarbon (PAH) degraders and the differences in denaturing gradient gel electrophoresis patterns compared with those of the reference site. Members of the classes Alphaproteobacteria and Actinobacteria were the prevailing groups of bacteria detected in both matrices, although the sand bacterial community exhibited higher species richness than the rock bacterial community did. Culture-dependent and -independent approaches suggested that the genus Rhodococcus could play a key role in the in situ degradation of the alkane fraction of the Prestige fuel together with other members of the suborder Corynebacterineae. Moreover, other members of this suborder, such as Mycobacterium spp., together with Sphingomonadaceae bacteria (mainly Lutibacterium anuloederans), were related as well to the degradation of the aromatic fraction of the Prestige fuel. The multiapproach methodology applied in the present study allowed us to assess the complexity of autochthonous microbial communities related to the degradation of heavy fuel from the Prestige and to isolate some of their components for a further physiological study. Since several Corynebacterineae members related to the degradation of alkanes and PAHs were frequently detected in this and other supralittoral environments affected by the Prestige oil spill along the northwestern Spanish coast, the addition of mycolic acids to bioremediation amendments is proposed to favor the presence of these degraders in long-term fuel pollution-affected areas with similar characteristics.Since the Polycommander accident, many other oil spills, such as the Urquiola (1976), Andros Patria (1978), and Aegean Sea (1992) spills, have occurred on the Galician coast (northwestern Spain), where intense maritime traffic takes place. On 13 November 2002, the oil tanker Prestige sprang a leak off Cape Finisterre (Galicia, northwestern Spain) and 6 days later its oil tank broke up and sank 240 km west of Galicia. The spill of 60,000 tons of heavy fuel oil polluted 500 miles of the Spanish coast, reaching the French coast. The Costa da Morte, northwestern Spain, was the most affected area (2). The oil residue released by the Prestige was devoid of the more labile fractions (boiling point, <300°C), with high levels of aromatic hydrocarbons (∼50%), as well as resins and asphaltenes (∼30%) (6).Information about the autochthonous microbial populations at maritime oil-polluted sites is scarce (23). The studies carried out after the Nakhodka spilled oil with a chemical composition similar to that of the Prestige fuel, gathered information on the marine microbial populations that adapted to heavy fuel oil. Different molecular approaches, mainly involving 16S rRNA gene analyses such as PCR-denaturing gradient gel electrophoresis (DGGE) (31), clone libraries, and specific oligonucleotide probes (43), were used to describe the bacterial communities established in different environments and at different time intervals after the oil spill.Most of the previous studies were focused either on the isolation of a few culturable degrading strains or just on detecting the 16S rRNA gene sequences of all of the bacteria present in polluted samples without gathering information on their physiology. As a consequence, more efforts should be made to understand community structures in situ and to isolate the key oil-degrading species present, with the aim to further investigate their requirements (23, 58) that could be used in the development of new bioremediation.In the present report, we describe a microbiological analysis of a cobblestone beach on the Costa da Morte, northwestern Spain, affected by the Prestige heavy fuel oil spill 12 months after the last fuel stranding. The microbial community was examined thoroughly by a triple-approach method based on different cultivation strategies and culture-independent methods such as DGGE and the screening of 16S rRNA gene clone libraries.     

Three new species of Prosorhynchoides (Digenea: Bucephalidae) from Tylosurus gavialoides (Belonidae) in Moreton Bay,Queensland, Australia

We surveyed 30 individuals of Tylosurus gavialoides (Castelnau) (Belonidae) collected from Moreton Bay, Queensland, Australia, and describe three new species of Prosorhynchoides Dollfus, 1929 from them. The new species are morphologically distinct from existing Prosorhynchoides spp. and 28S and ITS-2 ribosomal DNA data further supports our morphological findings. We also conduct the first mitochondrial DNA analysis of species of Prosorhynchoides. The new species from T. gavialoides form a strongly supported clade on the basis of the two ribosomal markers, further supporting the emerging hypothesis that bucephaline clades are strongly associated with host groups. We have not observed any of the new species reported here in over 3500 surveyed individuals of other piscivorous fish in Australia, suggesting that these species are host-specific at least to belonids, if not to only T. gavialoides. Our findings support previous reports that suggest that belonids are exceptional hosts for bucephalids. We predict that further sampling of the numerous other belonid species present in Australian waters, for which nothing is known of the bucephalid fauna, will uncover further bucephalid richness.     

Seasonal changes in the chemical composition of red deer (Cervus elaphus) semen

During reproductive quiescence, apart from a rapid decrease in total protein content, there was a 2–3 fold decrease in the activity of certain enzymes (glutamic-oxaloacetic transaminase (GOT), alkaline phosphatase, acrosin inhibitors) in the seminal plasma of red deer stags. The activity of the enzymes of the spermatozoa, hyaluronidase and acrosin, increased in the seminal plasma, probably due either to ageing of the spermatozoa, accumulated in the epididymis, or to changes in the permeability of cell membranes.These phenomena were accompanied by an increased concentration of albumins originating in blood, and by a noticeable disappearance of globulin fractions. This would point to a change in the permeability of the tissue barriers in the deer stag reproductive system, and to a decreased rate of protein synthesis in particular sections of this system, especially in the epididymis, during reproductive quiescence.     

Respiration and nitrogen excretion of Polinices alderi (Forbes) and Polinices catena (da Costa) (Gastropoda : Naticidae)

Measurements were made of oxygen consumption and NH₃-N excretion, at different temperatures, for two species of gastropod molluscs, Polinices alderi (Forbes) and P. catena (da Costa), preying on bivalve molluscs. Previous observations, for P. alderi, that the rate of oxygen consumption is influenced by diet were confirmed. The effect of temperature on the rates of respiration and excretion was compared for the two species. Oxygen consumption was temperature dependent, with Q₁₀ values of ≈2, in the temperature range 10–20°C, for both species. NH₃-N excretion was relatively insensitive to temperature over the same range. The ratio of oxygen consumed to nitrogen excreted (O:N ratio) was relatively independent of size for both species, but was influenced by diet.