Bioaccumulation and toxic effects of copper on growth and oxygen consumption by the postlarvae of Penaeus indicus

The aim of this study was to assess the toxic impact of copper on postlarvae (PL) of the penaeid shrimp Penaeus indicus. Tolerance, growth, oxygen consumption and metal accumulation were investigated in these PL on exposure to copper. Tolerance studies were conducted for 96 h to assess the tolerance limits of P. indicus PL exposed to different concentrations of copper using static renewal bioassay tests. Using the Probit method, the regression equation was calculated as Y=0.4899+2.3562 X, with a correlation coefficient of 0.9707. The 96 h LC₅₀ was 0.8204 ppm. The effect of sublethal (one-fifth of 96 h LC₅₀) copper on PL for short- and long-term exposures revealed a significant (p<0.05) decrease in the rate of oxygen consumption, metabolic rate, mean length, wet and dry weight of the exposed PL over their respective controls which can be attributed to a gradual and time-dependent accumulation of the metal, as noticed in the exposed PL through accumulation studies. Overall, the data suggest that on chronic exposure even sublethal concentrations of copper can reduce the metabolic rate and growth in P. indicus PL. This is perhaps the first attempt to use the wild P. indicus PL as a bioindicator of copper toxicity.     

Interaction of temperature and salinity on oxygen consumption of the estuarine crab Panopeus herbstii

Marine Biology - The combined effects of temperature and salinity on the rate of oxygen consuption by the estuarine crab Panopeus herbstii Milne-Edwards (Crustacea: Decapoda: Xanthidae) were...     

Effect of salinity on hemolymph calcium concentration during the molt cycle of the prawn Penaeus monodon

Prawns (Penaeus monodon) were obtained from ponds in Iloilo, Philippines, in 1984 and 1985 and maintained in salinities from 8 to 44. Total hemolymph calcium was largely affected by molt stage and less so by salinity. A sharp, transient increase in hemolymph calcium occurred 3 to 6 h postmolt, followed by an equally rapid decrease from 6 h postmolt to intermolt. This biphasis response was limited to prawns in 8, 20 and 32S; in 44S, hemolymph calcium remained the same throughout the sampling period. Peak concentrations of total calcium were greater in low (8 and 20S) than in high salinities. Salinity had no effect on the duration of molt cycle nor on time of occurrence of molt. Almost half of molting incidents occurred between 18.01 and 0.00 hrs, and one-third between 0.01 and 06.00 hrs.     

Effect of salinity on oxygen consumption in postlarvae of the penaeid shrimps Penaeus monodon and P. stylirostris without and with acclimation

The effects of salinity on oxygen consumption was investigated in cultured Penaeus monodon Fabricius and P. stylirostris Stimpson postlarvae (32 and 35 d after metamorphosis, respectively). In both species, no difference appeared between non-acclimated and fully-acclimated individuals. The metabolic rate was unaffected by salinity variations, but P. stylirostris displayed a tendency (non-significant at P<0.05) to increase respiration at lower salinities. These observations are discussed in reference to the ecology of the young prawns.     

Influence of activity and salinity on the weight-dependent oxygen consumption of the rainbow trout Salmo gairdneri

Two types of secretory cell have been found in the cement glands of the cypris larva of Balanus balanoides (L.). Histochemical tests show the presence of proteins, phenols and the enzyme polyphenol oxidase in both the glands and secreted cement. It is proposed that cyprid cement is composed of tanned protein, all the components of which are derived from the cement glands.     

Influence of environmental salinity on oxygen consumption and ammonia excretion of the arctic under-ice amphipodOnisimus glacialis

Changes in salinity affect the metabolic rate of the sympagic amphipodOnisimus glacialis collected from the Barents Sea in 1986 and 1988. When transferred from 35 to 5 ppt S, oxygen consumption and ammonia excretion both increase three-fold during the first 5 h of exposure, and they remain high throughout the rest of the experimental period (26 h). During 24-h acclimation to various salinities (5 to 45 ppt), the amphipods exhibit a respiratory and excretory response to hyper- and hypoosmotic stress; however, a rather constant O:N atomic ratio (around 15) was obtained at the experimental salinities, indicating protein/lipids as metabolic substrate. Both rates of oxygen consumption and ammonia excretion increased with an increasing osmotic difference (0 to 650 mOsm) between the haemolymph and the environmental medium, indicating higher energy requirements for osmotic and ionic regulation at low salinities. In amphipods abruptly transferred from 35 to 5 ppt, a minor decrease of the haemolymph sodium concentrations together with an increased ammonia excretion output indicate a counter-ion regulation of NH ₄ ⁺ and Na⁺ during hyposmotic stress.     

Oocyte development in the kuruma prawn Penaeus japonicus

Female kuruma prawns (Penaeus japonicus Bate) with undeveloped, early developing, developing, nearly ripe and ripe ovaries, were collected from Ise Bay, Japan, in 1984. Oocyte development of the kuruma prawn was classified into ten stages according to morphological characters, namely: (1) synapsis stage, (2) chromatin nucleolus stage, (3) early perinucleolus stage, (4) late perinucleolus stage, (5) oil globule Stage I, (6) oil globule Stage II, (7) yolkless stage, (8) yolk granule stage, (9) prematuration stage, and (10) maturation stage. The synapsis stage is a multiplication stage. The chromatin nucleolus stage, early and late perinucleolus stages are previtellogenesis and primary growth stages. Oil globule Stage I is an initial stage of primary vitellogenesis and secondary growth. Follicle cells on the oil globule Stage I oocytes expand rapidly and reach maximum size during oogenesis. Yolk granule stage oocytes are in the initial stages of secondary vitellogenesis. Strongly acidophilic yolk granules accumulate within basophilic vesicles of the cytoplasm. The yolk granules are first concentrated in the inner part of the cytoplasm, then gradually spread to the periphery. Cortical crypts, which are separated from the oocyte cytoplasm by the cytoplasmic membrane, are situated outside of oocyte cytoplasm. Germinal vesicle breakdown (GVBD) is initiated in the late phase of prematuration and continues until the late phase of maturation immediately prior to spawning. At the beginning of the maturation stage, the oocytes are ovulated, after which the nuclei further shrink and migrate out-wards. After ovulation, meiotic division of the ovarian oocyte progressed up to the metaphase of primary maturation division. Finally, the meiotic metaphase is visible just beneath the cytoplasmic membrane in the mature oocyte. Though ovulation is synchronous within the same ovary, GVBD is not completely synchronous. Ovulated mature oocytes have many club-shaped cortical crypts in the peripheral part of the cytoplasm and contain extensive accumulations of yolk granules dispersed throughout the cytoplasm. The apical end of the club-shaped cortical crypts and cytoplasmic membrane are coated by the vitellin envelope in the mature oocyte.     

Statolith implantation in the banana prawn Penaeus merguiensis

Specimens of Penaeus merguiensis de Man were captured between February and May 1981 from intertidal creeks and beaches of Cleveland Bay, Townsville, Australia, using a 15 m seine net. The statocyst of P. merguiensis resembles that of other macrurans in that it is a dorsal invagination of the basal antennular segment lined with groups of sensory hairs. The statolith is composed of sand grains implanted by the prawn from the substratum which must be done after every moult. Implantation begins within 90 min of ecdysis and has 3 phases: sifting; digging and finally eye withdrawal which pushes the sand grains into the statocyst chamber.     

Comparative study of the effects of temperature,salinity and oxygen tension on the rates of oxygen consumption of nauplii of different strains of Artemia

The effects of temperature, salinity and oxygen tension on the rates of oxygen consumption of three different strains of Artemia nauplii have been studied. When acclimated to a salinity of 30, nauplii from each of the three strains were able to maintain approximately constant rates of oxygen consumption over a wide range of oxygen tension. The ability to maintain respiratory independence during hypoxia was reduced, however, with an increase in either temperature or salinity. Nauplii of two of the strains (parthenogenetic diploid and tetraploid) showed a progressive increase in the rate of oxygen consumption with increasing temperature up to 35°C. Nauplii of the bisexual strain appeared to be less tolerant of exposure to temperatures >30°C, since at higher temperatures their oxygen consumption declined slightly. The differences between the nauplii of the different strains in their physiological responses to changing environmental conditions appear to correlate well with their seasonal occurrence in the field.     

Responses of hemolymph osmolality and tissue water of Penaeus chinensis Osbeck juveniles subjected to sudden change in salinity

Hemolymph osmolality and tissue water of laboratory-reared Penaeus chinensis Osbeck juveniles (0.83 to 1.86 g) were investigated, after they had been transferred individually from 10, 20, 30 and 40 ppt to 10, 20, 30 and 40 ppt for 0.25, 0.5, 1, 2, 5 and 10 d, respectively. Hemolymph osmolality and tissue water of shrimp were stablilized within 5 d after they had been subjected to a sudden change in salinity from each salinity level. Hemolymph osmolality had a positively linear relationship with medium osmolality. Tissue water decreased with increased medium osmolality, and decreased with increased hemolymph osmolality. The mean (SD) isosmotic point was 703 (8) mOsm kg^–1 which is equivalent to 24.2 (1.0) ppt. P. chinensis juveniles exhibited hyperosmotic regulation in salinities below isosmotic value, and hypoosmotic regulation in those above. The shrimp originally adapted to high salinity levels (30 and 40 ppt) showed less fluctuation of tissue water than those adapted to low salinity levels (10 and 20 ppt) when they were subjected to a sudden change in salinity.     

Population structure of the black tiger prawn, Penaeus monodon, among western Indian Ocean and western Pacific populations

We examined the population structure of the black tiger prawn, Penaeus monodon Fabricius, 1798, in the Indo-West Pacific by analyzing the geographic distribution of elongation factor 1-alpha intron sequences from specimens collected during the winter and spring of 1997. Both the molecular phylogeny of alleles and F-statistics indicated very strong differentiation between populations from the western Indian Ocean and western Pacific. This pattern is concordant with other recent studies of marine species in this region, implying that the Indo-Australian Archipelago represents a biogeographic break between populations in the Indo-West Pacific. F _ST-values among populations in the western Indian Ocean also indicate structure within this region, whereas no structure was found among western Pacific populations. Nucleotide diversity was significantly lower in the western Indian Ocean populations than in the western Pacific, implying that the populations have regional differences in demographic history. Received: 16 November 1998 / Accepted: 26 May 1999     

Persistent locomotor rhythmicity in the prawns Penaeus indicus and P. monodon

The locomotory activity of adult Penaeus indicus Milne Edwards and P. monodon (Fabricius) collected from the Vellar estuary, South India, in 1983 was monitored continuously for a period of 40 d in the laboratory. Both species exhibited persistent circatidal and circadian rhythmicity, the former displayed peak activity during predicated times of high water in their original habitat. The latter exhibited peak activity during periods corresponding to in situ night-time, with almost no activity during the day, except at the time of high tide. The tidal and daily rhythms were evident for only 3 to 4 d and 5 to 6 d, respectively, under laboratory conditions. The amplitude of the rhythms displayed variations in each semilunar period, reflecting the synchrony and dissynchrony of the tidal and daily rhythms. Activity was correlated with phases of the moon, peaking at times of new and full moon, and showing a scattered pattern with smaller peaks during the first and third quarters.     

Carotenoids in the tiger prawn Penaeus esculentus during ovarian maturation

Female Penaeus esculentus Haswell were collected by 15 to 20 min duration trawls during 1990. Carotenoids were analysed in the digestive gland, abdominal muscle, the remainder of the body (hereafter called integument) and ovary of prawns in Stage 2 through Stage 4 (fully mature) of maturation. The only oxycarotenoids (xanthophylls) identified were astaxanthins or astaxanthin esters; occasionally low levels of -carotene were detected in the digestive gland. The concentrations of astaxanthin monoesters (AM) and diesters (AD) were highest, with only minor amounts of free astaxanthins (Ast), except in the maturing ovaries, where free astaxanthins predominated (up to 80% of the total carotenoid). Of the total carotenoid, 82 to 94% was in the integument, but at maturity the digestive gland contained 10.7±3.4% and the ovary 5.6±0.9% of the total carotenoid. Only the ovary increased in mass during maturation, reaching up to 5.2% of total prawn mass. During this period, digestive gland concentrations of AM, AD and Ast all increased (tota 20 to 120 g g^-1); levels in the muscle and integument varied little throughout maturation (total 0.4 and 100 g g^-1, respectively); ovary AM levels remained low throughout (1.5 to 1.2 g g^-1), AD increased from only 2 to 5 g g^-1, but Ast increased from 2 to 34 g g^-1. Apart from the ovary, AM concentrations were the most variable. In common with other decapod Crustacea, the maturing ovary of P. esculentus contained high levels of carotenoids, indicating that these may have an important role in early development. The natural diet of P. esculentus includes a variety of carotenoids, but except for a little -carotene, the digestive gland, where absorption occurs, contained astaxanthins, with only an occasional trace of -carotene. This suggests that the conversion of dietary carotenoids to astaxanthin occurs soon after ingestion.     

Setal development,moult-staging and ecdysis in the banana prawn Penaeus merguiensis

Specimens of juvenile Penaeus merguiensis de Man (1888) were captured by seine netting from the shores of Cleveland Bay, Townsville, Queensland Australia between February 1980 and November 1981. Accurate determination of moult cycle stage can be achieved rapidly by microsopical examination of setal development in an excised whole pleopod. Four major stages and 5 substages within premoult were clearly defined. The rate of setogenesis varies along the length of a pleopod, precluding the examination of only one specific location on the pleopod for accurate moult cycle staging. The process of ecdysis lasts for no more than 40 s.     

The combined effects of high salinity and temperature on the survival of young Limanda limanda

Young specimens of the most common inshore flatfish, the dab Limanda limanda (Linnaeus, 1758), in the area of a proposed concentrated brine discharge, off the Yorkshire coast (England) were subjected to high salinities over temperatures corresponding to an annual temperature range. The results of these experiments have been used in the design of a dilution and dispersion system to protect the inshore fisheries. Mortality was found to be size-dependent, smaller dabs being least resistant. Response-surface analyses were utilised, showing mortality in relation to immersion time. The effect of temperature slowly declines with increased immersion time, and salinity becomes increasingly the more dominant effect. A significant salinity-temperature interaction was observed, which reached its peak effect at 3 h immersion. A 3-dimensional response-surface model of the mortality contours, for salinity, temperature, and immersion time, was produced which may be used to set upper limits to the design of the effluent disposal system. It is concluded that, provided salinity does not rise above 55, it is unlikely that significant changes in the L. limanda populations will occur.     

Effects of pressure,temperature and oxygen on the oxygen consumption rate of the Midwater copepod Gaussia princeps

In this study we assessed the amount of lead accumulated in the body of a grazing mollusc by transfer from its algal food in laboratory experiments, and compared these results with the amounts found in naturally occurring molluscs and seaweed. Near La Jolla, California (USA), where the concentration of lead in seawater is probably less than 0.08 g l^-1, most of the naturally occurring Egregia laevigata contains less than 0.4 g Pb g^-1 wet weight. The total body masses, without shells, of juvenile Haliotis rufescens fed on this seaweed for 3 to 6 months showed similar concentrations. When, however, E. laevigata is placed for 1 to 6 days in seawater to which lead has been added (0.1 or 1.0 mg l^-1) both the seaweed and the abalone subsequently fed with it accumulate proportionally larger amounts of lead. After 6 months, young abalone fed on E. laevigata pretreated with 1.0 mg Pb l^-1 accumulated up to 21 g Pb g^-1 wet weight. This amount of lead had no apparent consequences on the growth or activity of the molluscs. Analyses of 6 different organs from adult abalone showed that the lead was selectively concentrated in the digestive gland. In the foot (muscle tissue), which is the part normally consumed by humans, only negligible amounts were found.     

Structure and function of the chelate pereiopods of the banana prawn Penaeus merguiensis

Penaeus merguiensis de Man systematically searches the substratum and removes small particles of food from it using the small chelae of the first three pairs of pereiopods. One or more chelae are used to transfer food particles to the mouth. The propus and dactylus of these limbs bear numerous setae arranged in discrete groups along the length of the segments. The tip of each seta is elaborately sculptured and has a large sub-terminal pore. It is probable that these are chemosensory organs responsible for discriminating edible from non-edible material. Proximal to almost every setal group is a much-branched seta (rarely two) which probably measures the depth to which the chela has been inserted into the substratum. At the articulation of the propus and carpus of the first pereiopod are three groups of differently sculptured setae, whose function is to clean the other chelate pereiopods. An elaborate system of pegs and a ridge on the apposable fringes of the chelae might be a mechano-receptive device with a particle size discriminating function. The ridges merge into opposable terminal denticulate pads whose function is to grasp food and other particles, which may be quite small (10 to 20 m upwards).     

Structure and function of the third maxillipeds of the banana prawn Penaeus merguiensis

The functions of the third maxilliped of Penaeus merguiensis de Man are described. It has a 6-segmented endopodite which is used in feeding, grooming and possible pheromone reception. In feeding, large pieces of food are gripped by the stout spines on inner borders of the ischia which hold them to the mouth so that particles can be torn off and ingested. All the distal segments have long setae used in grooming chelate pereiopods and the antennules. In mature males there is a tuft of about 300 slender setae at the end of the propus, but its function remains obscure.     

Variation in lipid classes during the molting cycle of the prawn Penaeus japonicus

The variation in the concentration and fatty acid composition of lipid classes during the molting cycle of the prawn Penaeus japonicus was investigated. The lipid concentration of the whole body reached a maximum at mid-premolt (Stage D₂) and then decreased to low level at late premolt (Stage D_3–4). The accumulation of lipids during the premolt period seemed to be attributable to the increase of both polar and neutral lipids. The increase of neutral lipids at Stage D₂ was derived from not only triglycerides but also free sterols and free fatty acids. Regarding the fatty acid composition of every lipid class, a marked variation occurred mainly at the intermolt (Stage C). In this stage, the polar lipids were rich in monoenoic acids such as 18:1 and poor in polyenoic acids such as 20:53 and 22:63. The triglycerides were rich in polyenoic acids at Stage C, but poor in monoenoic acids such as 16:1 and 18:1. The steryl esters contained large amounts of saturated acids such as 16:0 and 18:0 throughout the molting cycle, however the level of polyenoic acids increased at Stage C.     

Influence of food concentration,temperature and salinity on the larval development ofBalanus amphitrite

Influence of food concentration (0.5, 1 and 2 x 10⁵ cell ml^–1 ofSkeletonema costatum), temperature (20 and 30°C) and salinity (15, 25 and 35) on the larval development ofBalanus amphitrite (Cirripedia: Thoracica) was examined. The mortality rate at 20°C was lower than at 30°C in general. Increase in food concentration from 0.5 to 1 x 105 cells ml^–1 improved the survival rate, but this was not evident when food concentration was increased to 2 x 105 cells ml^–1. The results indicate that food availability and temperature jointly determine the energy allocation for metamorphic progress. It was observed that the influence of the tested variables varied with instar. At 20 °C the mean duration of the second instar exceeded 3 d and was much longer than other instar durations. The fourth, fifth and sixth instars and the total naupliar period showed that the effect of different salinities at given food concentrations was negligible at 20°C, while at 30°C there was a marked decrease in duration with increasing salinity.