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.     

Studies on the causes of mortality of the estuarine bivalve Macoma balthica under conditions of (near) anoxia

Survival of the bivalve Macoma balthica in (near) anoxic seawater was studied in a static system and a flow-through system and compared with emersed exposure to air and N₂. In the static system, a decrease in pH and exponential accumulation of sulphide in the incubation medium were observed, indicating excessive growth of (sulphate-reducing) bacteria. These changes in the chemical environment were prevented by the use of a flow-through system. However, this treatment hardly affected survival time. Median mortality times were 8.3 and 9.0 days for the static and flow-through incubation, respectively. Addition of the antibiotic chloramphenicol strongly increased survival time in both systems with corresponding values of 17.9 and 23.0 days. A similar value was obtained for survival in air (LT₅₀= 21.7 days). In a second experiment (1 year later), we obtained much lower values for anoxic survival in a static system, although laboratory conditions, season and temperature were similar. The pH values were adjusted to 6.5, 7.2 and 8.2 by buffering the media (25 mM Tris-HCl), and the corresponding LT₅₀ values were 5.5, 5.7 and 4.7 days, respectively. In the presence of chloramphenicol the values were 10.8, 10.9 and 9.5 days, respectively. These values show that a slightly acidic medium increased survival time. Exposure to an atmosphere of N₂ resulted in a survival time close to that in anoxic seawater without chloramphenicol (LT₅₀= 6.4 days). Overall the results indicate that proliferation of anaerobic bacteria associated with the bivalves was the main cause of death. Since chloramphenicol also displayed a strong positive effect in the flow-through system, which prevented the accumulation of released waste products and a decrease of pH, bacterial damage must have been by injury of the tissues of the clams and not by the release of noxious compounds to the medium. Bacterial outbreaks are a part of every anoxic event (eutrophication), and therefore, in their habitats, direct bacterial infection may also be the cause of clam mortality. It is concluded that laboratory studies on anoxic tolerance, or impact of sulphide, may produce artefacts when no precautions are taken to suppress bacterial proliferation. Received: 4 July 2000 / Accepted: 6 December 2000     

Growth and population structure in the infaunal bivalve Yoldia eightsi in relation to iceberg activity at Signy Island,Antarctica

Growth rates in the infaunal nuculanid bivalve mollusc Yoldia eightsi (Couthouy) were assessed for field populations in Factory Cove, Signy Island, Antarctica, between. February and April 1992. Daily increments in length (maximum shell dimension) ranged from 2.3 m d^-1 for a 30 mm individual to 5.1 m d^-1 for a 10 mm specimen. These growth rates were converted to annual increments, based on a growing season for the Signy population of around 5 mo, and ages for the largest individuals in the population (35 mm in length), were calculated to be 65 yr. Specimens of 43 mm in length have been found near this site and, if their growth rates are similar to this population, their ages would be in the order of 120 yr. Size distributions from two sites in the same Y. eightsi bed 300 m apart showed significant differences. At the more exposed site the distribution was dominated by small juveniles, with 86% of the population 10 mm in length, while 13% were >20 mm in length. At the less exposed site the values were 27% <10 mm and 56% >20 mm. Icebergs have often been seen grounded on the Y. eightsi bed in this study, especially on the exposed outer portion. This factor, in association with inhibition of larval settlement by high densities of large individuals, is proposed as an explanation of the observed population distributions and the absence of very large specimens in the Factory Cove population.     

Influence of an artificial reef on the surrounding infaunal community

Artificial reefs have been constructed throughout the world, but their effects on adjacent soft-bottom communities are largely unknown. In December 1986, we investigated the influence of Pendleton Artificial Reef (PAR) in Southern California on the abundance of infauna in the surrounding sand bottom. PAR was constructed in 1980 of quarry rock placed in eight piles, or modules. The artificial reef altered the grain-size distribution of sediments around the reef; sediments close to the modules were coarser than those 10 or 20 m away from the modules. Densities of one of the two most common species, the polychaetePrionospio pygmaeus, were lower near the reef, perhaps due to foraging by reef-associated predators or because the habitat near the reef was less suitable. We found no evidence that foraging by reef-associated fishes caused a widespread reduction in infaunal densities near the reef, and in fact the other most common taxon,Spiophanes spp., had higher densities near the reef. The most conspicuous effect of the artificial reef concerned the tube-dwelling wormDiopatra ornata, which only occurred in close association with the modules. In addition, total infaunal density and the densities of decapods, echinoderms and sipunculids were higher withinD. ornata beds than outside the beds. These results indicate that the densities of some species were enhanced, and others depressed, around the reef, but that the overall effect of the artificial reef on the surrounding infauna was limited to a small area near the modules.     

Some influences of temperature on the rearing of the grunion Leuresthes tenuis,an atherine fish

Grunion Leuresthes tenuis (Ayres), an atherine fish, were reared, from artificially fertilized eggs to 160 days posthatching, at temperatures from 18.0° to 25.4° C. The rearing was carried out in five 60 l rectangular containers and two hard moulded plastic pools holding 60 and 450 l. The growth rate was highly correlated with temperature at least up to metamorphosis. Thereafter, the effect of temperature on growth, within lethal limits, appeared to be lost or at least masked by other factors. At low densities, after metamorphosis, growth was proportional to the population density. Size and shape of the rearing containers also influenced the growth rate.     

Energy relations of the bivalve Mercenaria mercenaria on an intertidal mudflat

Measurements of the filtration rate and oxygen consumption of the bivalve Mercenaria mercenaria (L.) have been made using flowing water systems, and then combined with growth and survivorship data to construct an energy budget for a tidal-flat population in Southampton Water. Estimated consumption (1292 kcal m^-2 year^-1) is mainly deposited as faeces and pseudofaeces (759 kcal) or excreted (160 kcal); 29% (374 kcal) is assimilated, of which 241 kcal are used for respiration, 72 kcal for flesh production and 61 kcal for gamete production. M. mercenaria contributes significantly to other trophic groups in Southampton Water; predators remove an estimated 55 kcal m^-2 year^-1, and 829 kcal pass to the scavenger/decomposer chain.     

硫化物胁迫对日本沼虾呼吸代谢和能量代谢酶的影响

研究了硫化物暴露后日本沼虾细胞色素氧化酶(CCO)、琥珀酸脱氢酶(SDH)、延胡索酸还原酶(FRD)和乳酸脱氢酶(LDH)4种呼吸代谢酶及能量代谢酶-精氨酸激酶(AK)活性的变化规律.将日本沼虾暴露于0.6 mg·L~(-1)、2mg·L~(-1)的2个硫化物质量浓度组和不含硫化物的对照组水体中,暴露后0、2、12、24、48 h和解除暴露后48 h取肝胰腺和肌肉组织进行酶活性分析.结果显示:肝胰腺和肌肉组织SDH和CCO活性随硫化物质量浓度升高或暴露时间延长而显著降低(P<0.05).FRD、LDH和AK活性随硫化物质量浓度升高或暴露时间延长而显著升高(P<0.05).解除硫化物暴露后48 h,各质量浓度组酶活性与对照组无显著差异.上述酶活性还存在组织差异,肝胰腺呼吸代谢酶活性高于肌肉中相应酶活性,而AK活性与此相反.结果表明,硫化物胁迫导致日本沼虾有氧呼吸代谢减弱,无氧呼吸代谢增强,并动用其能量贮存物质磷酸精氨酸,产生更多ATP以适应外界不良环境.     

Relationship between depth, sediment, latitude, and the structure of benthic infaunal assemblages on the mainland shelf of southern California

A regional benthic survey was conducted in 1994, and the data were used to assess the relationship among three habitat factors (depth, sediment grain size, and latitude) and the distribution of benthic infaunal assemblages on the southern California coastal shelf. Benthic samples were collected with a 0.1 m² Van Veen grab from 251 sites on the continental shelf (10–200 m deep) from Point Conception, California, to the United States–Mexico international border. The relationship between habitat and assemblages was investigated by conducting a Q-mode cluster analysis to define groups of stations with similar species composition and then examining whether differences were present in physical habitat attributes among those groups of stations. Analysis of data from 175 uncontaminated sites yielded four habitat-related benthic infaunal assemblages along the southern California coastal shelf: a shallow-water assemblage from 10–32 m, a mid-depth assemblage between 32 and 115 m, and two deep-water (115–200 m) assemblages, one in fine and one in coarse sediments. These empirically defined points in the depth and sediment grain size gradients can be used to define reference habitats for the development of biocriteria. Benthic abundance and diversity were greatest in the mid-depth assemblage, conforming to predictions for benthic assemblages in regions of upwelling. Within the 500 km of coastline examined, latitude was not an important factor in defining assemblages. Received: 3 December 1999 / Accepted: 9 October 2000     

Toxicokinetics,metabolism, and microsomal studies of chlorpropham in rats

A study on the toxicokinetic behavior, metabolism of chlorpropham, and its effect on cytochrome P₄₅₀ from liver microsomes was carried out in albino rats after a single and consecutive oral administration at 500?mg?kg^?1 body weight for 10 and 20 days. Chlorpropham was detected in the blood at 0.08?h (11.43?±?1.72?µg?mL^?1) reaching a maximum concentration at 2?h (30.90?±?2.55?µg?mL^?1) and a minimum at 48?h (1.95?±?0.20?µg?mL^?1) after a single oral administration of 500?mg?kg^?1. The absorption rate constant (K _a) was 0.66?±?0.48?h^?1. The Vd _area (18.01?±?2.78?L?kg^?1) and t _1/2 β (12.23?±?1.96?h) values suggested a wide distribution and long persistence of the compound in the body, respectively. The higher Cl_R (0.82?±?0.00?L?kg^?1?h^?1) compared to Cl_H (0.18?±?0.02?L?kg^?1?h^?1) value indicated that a major portion of chlorpropham was excreted through the urine (30%) compared to the faeces (2.81%). Chlorpropham residue was detected in all tissues of rat at 0.25?h while its metabolite, meta-chloroaniline was detected in liver, kidney, heart, lung, and spleen tissue at 0.25?h. Meta-chloroaniline was not detected in skeletal muscle, brain, fat, and stomach tissue at any time of the observation period. Maximum concentrations of chlorpropham and meta-chloroaniline were detected at 2?h (except in the spleen), and minimum concentrations of chlorpropham at 24 (heart, lung, spleen, skeletal muscle, and stomach) and 48?h (liver, kidney, brain, and fat tissue) respectively; and meta-chloroaniline at 24?h (except heart and spleen). The tissue half-life of chlorpropham in rat varied from 3.80 to 11.60?h. Repeated oral administration of chlorpropham at 500?mg?kg^?1 for 10 and 20 days caused an induction of the liver microsomal pellet of rat.     

Comparative studies on the metabolism of shallow-water and deep-sea marine fishes. III. Apparatus for studies of tissue preparations under high hydrostatic pressures

Design information is given for hydrostatic-pressure apparatus permitting either intermittent or continuous monitoring of the rates of nonoptically observable biochemical and physiological processes in the fluids supporting surviving preparations of living tissues or tissue fractions. Semi-micro scale experiments can be carried out over the full range of temperatures and hydrostatic pressures occurring in the oceans of the world. Samples are obtained at 1 atm pressure, whatever the experimental pressure. The apparatus is simple to use, safe, reliable, and readily portable for work on shipboard. Specially designed components described in detail are: magnetically stirred pressure vessels, sampling valves, and magnetic stirrer drive.     

Accumulation of cadmium by larvae and adults of an Hawaiian bivalve,Isognomon californicum,during chronic exposure

Larvae and adults of an Hawaiian bivalve, Isognomon californicum, were exposed to sublethal, environmentally realistic concentrations of cadmium (2 and 20 ppb) for 28 d, and the accumulation of cadmium was evaluated. The concentrations of cadmium were expressed in terms of total cadmium (tissue and shell concentrations combined) and tissue cadmium. The accumulation rates of larvae were one to two orders of magnitude greater than adult rates. This study suggests that the faster uptake rates of larvae may explain why larvae are more sensitive than adults. Furthermore, the magnitude of differences between larval and adult accumulation rates may be related to metabolic rate. When larvae and adults were exposed to cadmium for only 14 d, followed by a 14 d depuration period, a substantial loss of cadmium was observed during the depuration period. Possible accumulation mechanisms and their similarity between larvae and adults are discussed.     

Effects of starvation,and light and dark on the energy metabolism of symbiotic and aposymbiotic sea anemones,Anthopleura elegantissima

Rates of oxygen and carbon-dioxide exhange were measured in symbiotic and aposymbiotic specimens of the sea anemone Anthopleura elegantissima while fed and starved under light or dark conditions. Respiratory quotients indicated that fed anemones switched from a carbohydrate to a fat catabolism when starved, with the exception that symbiotic individuals starved in the light showed a pronounced carbohydrate catabolism for over 1 month. The source of the carbohydrate was probably photosynthate translocated by the dinoflagellate Symbiodinium (=Gymnodinium) microadriaticum (Freudenthal) living in the anemones' tissues. The starved symbiotic anemones maintained in the light had lipid levels not significantly different from fed controls and 44 to 61% higher than starved aposymbiotic anemones after 1 month. Thus, the quality and quantity of the metabolic flux from the symbionts to the sea anemone were sufficient to conserve the host's lipid reserves.     

Metabolic responses of the prawns Palaemon elegans and P. serratus (Crustacea: Decapoda) to acute hypoxia and anoxia

Using prawns, Palaemon elegans (Rathke) from intertidal pools on the Isle of Cumbrae, Scotland, and P. serratus (Pennant) from the subtidal at Plymouth, England, some metabolic responses to hypoxia and anoxia have been studied. P. elegans was found to have a greater tolerance of severe hypoxia than P. serratus. Tolerance of totally anoxic conditions, however, was limited to only 4 h in P. elegans and to approximately 1 h in P. serratus. exposure to moderate hypoxia (30 torr) resulted in little change in the concentration of L-lactate in the blood or in the tissues of either P. elegans or P. serratus. When exposed to extreme hypoxia (10 or 5 torr for P. elegans), however, there was a progressive increase in the concentration of L-lactate in the blood and in the tissues of both species. After normoxic conditions had been restored, the concentration of L-lactate in the blood and in the tissues returned to normal resting levels more rapidly in P. elegans than in P. serratus. Under hypoxic conditions, both P. elegans and P. serratus showed an increase in the concentration of blood glucose and a slight reduction in the glycogen content of the tissues. The concentrations of blood glucose and of tissue glycogen returned to normal levels within 6 h of the prawns being returned to normoxic conditions. The results of an in situ study in April and August 1986 to examine the metabolic responses of P. elegans to the hypoxic conditions normally experienced in high-shore rock pools are also presented. The ecological significance of the differing abilities of these species to survive hypoxic exposure is discussed.     

Comparative studies on the metabolism of shallow-water and deep-sea marine fishes. II. Red-muscle metabolism in shallow-water fishes

Maximal rates of oxygen consumption in vitro have been measured under standardized conditions at three test temperatures (5°, 15°, 25°C) on minced preparations of red muscle from 10 species of shallow-water marine teleost fishes. These fishes came from three different geographic areas, two with cool average water temperatures (near 15°C: coastal southern California, Galápagos Islands) and one with warm average water temperatures (near 25°C: Hawaiian Islands). The group is made up of post-juvenile or adult epipelagic fishes, which are moderately or very active in terms of their locomotor activities. A large part of the range of phylogenetic diversity among the teleosts is represented, as is the body weight range from a few grams to several kilograms. The purpose of the work is to provide part of a set of tissue-metabolism data on shallow-water fishes for future comparison with similar results from deep-sea species. Of 8 complete curves for oxygen uptake rate versus temperature (R-T curves), 6 are normal in shape (Q₁₀1.5), 1 is normal but with a low Q₁₀, and 1 is partly flat, partly normal. The differences between the species in terms of both absolute positions and slopes of the R-T curves are not related in any consistent way to any of the three testable variables: phylogenetic position, long-term adaptation temperature, and body size. The red muscles of a variety of adult epipelagic fishes, at ecologically realistic temperatures, are shown to be exceptions to the general rule that tissues of ectothermous lower vertebrates have lower metabolic rates than comparable tissues of non-torpid endothermous higher vertebrates. This circumstance probably is a major factor in the great capacities for sustained high-speed swimming shown by most epipelagic fishes. Other physiological and ecological implications of the results are discussed.     

Comparative studies on the metabolism of shallow-water and deep-sea marine fishes. I. White-muscle metabolism in shallow-water fishes

Maximal rates of oxygen consumption in vitro have been measured under standardized conditions at three test temperatures (5°, 15°, and 25°C) on minced preparations of white muscle from 39 species of shallow-water marine teleost fishes. These fishes came from four different geographic areas, two with cool average water-temperatures (near 15°C: coastal southern California, Galápagos Islands) and two with warm average water-temperatures (near 25°C: Hawaiian Islands; Bermuda). The group includes species covering much of the range of variation to be found among the teleosts with respect to five additional variables: phylogenetic position, type of environment, body weight, activity level, and growth stage. The purpose of the work is to provide part of a base line of tissue-metabolism data on shallow-water fishes for comparison with similar results from deep-sea species. Major conclusions from statistical analyses of the results are: four groups of shapes of oxygen-uptake rate versus temperature curves exist: normal, flat, dipped and peaked. Over 50% of curves are normal. Intra-group differences, contributing significantly to the total variance of the results at given test temperatures, are: cool versus warm average environmental temperatures primarily for epipelagic species; epipelagic versus non-epipelagic environments; very active species versus all others; juvenile stages versus adults. In each case, the subgroup first mentioned shows higher muscle oxygen-uptake rates than the other subgroup. Variables not contributing significantly to the total variance are phylogenetic position and body weight. Physiological and ecological implications of these results are discussed.     

Salinity and substratum effects on condition index of the bivalve Rangia cuneata

The condition index (CI) of the clam Rangia cuneata was measured monthly at 8 stations in 2 substrate types and 3 salinity regimes in the James River estuary, Virginia, USA. CI was higher in clams from sand bottoms than from mud, and decreased in both substrata in fresher water. Values were lowest in early spring and at a maximum in early autumn, with a pronounced autumn peak in the sand substratum. This pattern coincided with the annual salinity cycle. A field experiment showed that some factor associated with the water overlying a sand or mud substratum, rather than the nature of the substratum itself, was important in determining CI. The hypothesis is presented that this factor may be the higher suspended solids concentrations measured immediately over mud bottoms.Virginia Institute of Marine Science Contribution No. 782.     

Free amino acids and energy metabolism in eggs and larvae of seabass, Lates calcarifer

Contents of free amino acids (FAA), protein and ammonium ions together with rates of ammonia excretion and oxygen consumption were measured in order to study the role of FAA as an energy substrate in developing eggs and larvae of seabass (Lates calcarifer) maintained in seawater (30 ppt) at 28 °C without feeding. Initially eggs contained 25.3 nmol ind⁻¹ of FAA of which 21.5 nmol was rapidly utilised by the developing eggs and larvae during the period up to 40 h post spawning (PS) when nearly all the yolk had been resorbed. During the same period, a net increase in protein content of 1.7 μg ind⁻¹ was observed, indicating that the major part of the amino acids lost from the free pool had been polymerised into body proteins. Assuming that the balance of the FAA after protein synthesis was used entirely for energy metabolism, FAA appeared to be an important energy substrate during the embryonic stages (2 to 16 h PS); after hatching, the contribution of FAA to energy metabolism was less significant. From 50 h PS until the end of the study period at 100 h PS, amino acids derived from somatic protein were used for energy metabolism. For the overall period from just after spawning up to 100 h PS, the data indicate that ca. 14% of the total aerobic energy metabolism was derived from amino acid catabolism. Received: 26 September 1997 / Accepted: 1 April 1998     

Contrasting pattern of mitochondrial population diversity between an estuarine bivalve, the Kumamoto oyster Crassostrea sikamea, and the closely related Pacific oyster C. gigas

The Kumamoto oyster (Crassostrea sikamea) shows a spatially restricted distribution, favoring estuarine tideland environment. On the other hand, the Pacific oyster (C. gigas) has a broader range of habitat. The present study compared the mitochondrial population structure between the two closely related species. For accurate species identification of oysters sampled from Japanese and East Asian continental coasts, we performed sequencing analysis of the mitochondrial DNA (mtDNA) and PCR-RFLP assay of the first internal transcribed spacer of nuclear rRNA genes. Then, we estimated the extent of population differentiation within each of C. sikamea and C. gigas based on the mtDNA data. Few haplotypes were shared among the sites of sampling in C. sikamea, which contrasted with an extensive haplotype sharing among C. gigas samples. We discuss the mechanisms of elevated population differentiation observed in C. sikamea in light of the ecology and the ancient ocean geography around the present-day habitats.     

Effects of salinity stress on neurotransmission, energy metabolism, and anti-oxidant biomarkers of Carcinus maenas from two estuaries of the NW Iberian Peninsula

This study investigated the effects of salinity on biomarkers of oxidative stress, energy metabolism, and neurotransmission of Carcinus maenas from an estuary low impacted by pollution and from an estuary under chemical stress in the NW Iberian Peninsula. Crabs were collected in the field and, following an acclimation period, they were exposed for 7 days to five salinity levels ranging from 4 to 45 psu. At the end of the exposure period, stress biomarkers were determined in samples of muscle and digestive gland. The biomarkers assessed in the muscle were the activities of the enzymes cholinesterases (ChE), of which acetylcholinesterase is involved in neurotransmission, and lactate dehydrogenase (LDH) and isocitrate dehydrogenase (IDH) that are involved in energy metabolism. The biomarkers assessed in the digestive gland were (1) the activities of the enzymes glutathione S-transferases (GST), glutathione reductase (GR), and glutathione peroxidase (GPx), involved in phase II biotransformation and the anti-oxidant defence system; (2) the levels of total glutathiones (TG), also belonging to the anti-oxidant system; and (3) the levels of lipid peroxidation as a measure of oxidative damage. The results showed a significant influence of salinity on neurotransmission, energy metabolism, anti-oxidant status, and oxidative damage of C. maenas. For some biomarkers, this influence was dependent on whether the crabs were collected at the low-polluted estuary or at the contaminated estuary. In particular, crabs collected at the low-polluted estuary showed altered neurotransmission and anti-oxidant defences (GR). Crabs collected at the impacted estuary showed alterations in neurotransmission, energy metabolism (IDH and LDH), biotransformation, and anti-oxidant defences (GST, GR, GPx, and TG), as well as in oxidative damage, indicating that salinity change superimposes higher stress on these organisms. For ChE, IDH, and TG, altered responses were induced by both hypo- and hypersalinity.