Palaemon Serratus Research Articles

Toxicity of Organic Compounds to Marine Invertebrate Embryos and Larvae: A Comparison Between the Sea Urchin Embryogenesis Bioassay and Alternative Test Species

This study investigated the toxic effects of the insecticides lindane and chlorpyrifos, the herbicide diuron, the organometallic antifoulant tributyltin (TBT), and the surfactant sodium dodecyl sulfate (SDS) on the early life stages of Paracentrotus lividus (Echinodermata, Euechinoidea), Ciona intestinalis (Chordata, Ascidiacea), Maja squinado and Palaemon serratus (Arthropoda, Crustacea) in laboratory acute toxicity tests. The assays studied embryogenesis success from fertilized egg to normal larvae in P. lividus (48 h incubation at 20 degrees C) and C. intestinalis (24 h incubation at 20 degrees C), and larval mortality at 24 and 48 h in M. squinado and P. serratus. For P. lividus, the median effective concentrations (EC50) reducing percentages of normal larvae by 50% were: 350 microg l(-1) for chlorpyrifos, 5500 microg l(-1) for diuron, 4277 microg l(-1) for SDS, and 0.309 microg l(-1) for TBT. For C. intestinalis, the EC50 values affecting embryogenesis success were 5666 microg l(-1) for chlorpyrifos, 24,397 microg (l-1) for diuron, 4412 microg l(-1) for lindane, 5145 microg I(-1) for SDS, and 7.1 microg l(-1) for TBT. The median lethal concentrations (LC50) for M. squinado larval survival were 0.84 microg l(-1) (24 h) and 0.79 microg l(-1) (48 h) for chlorpyrifos, 2.23 microg(l(-1) (24 h) and 2.18 microg l(-1) (48 h) for lindane, and 687 microg l(-1) (48 h) for SDS. For P. serratus the LC50 values obtained were 0.35 microg l(-1) (24 h) and 0.22 microg l(-1) (48 h) for chlorpyrifos, 3011 microg l(-1) (24 h) and 3044 microg l(-1) (48 h) for diuron, 5.20 microg l(-1) (24 h) and 5.59 microg l(-1) (48 h) for lindane, and 22.30 microg l(-1) (24 h) and 17.52 microg l(-1) (48 h) for TBT. Decapod larvae, as expected, were markedly more sensitive to the insecticides than sea urchins and ascidians, and SDS was the least toxic compound tested for these organisms. Lowest observed effect concentrations (LOEC) of TBT for sea urchin and ascidian embryos, chlorpyrifos and lindane for crustacean larvae, and SDS, were similar to those found in many coastal areas indicating that there would be a risk to invertebrate embryos and larvae from exposure in the field to these pollutants.

The hearing abilities of the prawn Palaemon serratus

The mechanism of sound reception and the hearing abilities of the prawn ( Palaemon serratus) have been studied using a combination of anatomical, electron microscopic and electrophysiological approaches, revealing that P. serratus is responsive to sounds ranging in frequency from 100 to 3000 Hz. It is the first time that the Auditory Brainstem Response (ABR) recording technique has been used on invertebrates, and the acquisition of hearing ability data from the present study adds valuable information to the inclusion of an entire sub-phylum of animals when assessing the potential impact of anthropogenic underwater sounds on marine organisms. Auditory evoked potentials were acquired from P. serratus, using two subcutaneous electrodes positioned in the carapace close to the supraesophageal ganglion and the statocyst (a small gravistatic organ located below the eyestalk on the peduncle of the bilateral antennules). The morphology of the statocyst receptors and the otic nerve pathways to the brain have also been studied, and reveal that P. serratus possesses an array of sensory hairs projecting from the floor of the statocyst into a mass of sand granules embedded in a gelatinous substance. It is the purpose of this work to show that the statocyst is responsive to sounds propagated through water from an air mounted transducer. The fundamental measure of the hearing ability of any organism possessing the appropriate receptor mechanism is its audiogram, which presents the lowest level of sound that the species can hear as a function of frequency. The statocyst of P. serratus is shown here to be sensitive to the motion of water particles displaced by low-frequency sounds ranging from 100 Hz up to 3000 Hz, with a hearing acuity similar to that of a generalist fish. Also, recorded neural waveforms were found to be similar in both amplitude and shape to those acquired from fish and higher vertebrates, when stimulated with low-frequency sound, and complete ablation of the electrophysiological response was achieved by removal of the statocyst.

FOOD AND FEEDING HABITS OF BAY AD FISH BAGRUS BAJAD (FORSSKAL, 1775) IN El-NOZHA HYDRODROME, ALEXANDRIA, EGYPT

In order to elucidate the food and feeding habits of Bagrus bajed fish, stomach contents of 188 specimens with total body length ranging from 22 to 71cm were examined. Samples were collected monthly during the period from July 2000 to December 2001 from the commercial catch of El-Nozha Hydrodrome. The results of relative gut index indicated that B. bajed is carnivore. The range of its food material is wide, including cichiid species (Oreochromis niloticus, Oreochromis aureus, Sarotherodon galilaeus and Tilapia zillii), mullets ( Mugil cephalus and Liza ramada ), Clarias garlepinus, fish eggs, amphipods (Corophium volutator), shrimps ( Leander serratus) , aquatic insects (chironomid larvae and Coleoptera), vegetable matter and detritus. The maximum feeding intensity was in spring, while the lowest was in winter. Seasonal variation in the diet composition of B bajed revealed that fish prey was the main food item eaten throughout the year except in spring, where it represents the second important food item- after crustaceans. Variation in food species with fish length revealed an increase in the percentage of fish prey in the diet of this species. The diversity in diet of B. bajed, revealed low values in spring increasing in autumn and winter to reach the maximum in summer. Selectivity coefficient for fish prey group of B. bajed showed that cichiid species were negatively selected (-0.08), while the positively selected fishes were Clarias gariepinus (+0^57) and mullets (+ 0.29).

Lipid dynamics during the embryonic development of Plesionika martia martia (Decapoda; Pandalidae), Palaemon serratus and P. elegans (Decapoda; Palaemonidae): relation to metabolic consumption

The present study examines the changes in volume and lipid biochemistry during the embryonic development of 3 temperate caridean species —Plesionika martia martia, Palaemon serra- tus and P. elegans —with similar reproductive strategies but occupying different ecological niches. Egg volume, water content and lipid embryonic metabolism are analysed and discussed in relation to early life history and environmental conditions. An increase in egg volume and water content during embryogenesis was noted in all species, although it was larger in P. serratus. P. serratus also had the largest eggs, followed by P. elegans and P. martia martia. The quantitatively most important fatty acids (FA) in the eggs are the saturates (SFA) 14:0, 16:0 and 18:0, the monounsaturates (MUFA) 16:1(n-7), 18:1(n-9) and 18:1(n-7), and the polyunsaturates (PUFA) 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3) (eicosapentaenoic acid, EPA) and 22:6(n-3) (docosahexaenoic acid, DHA). Looking at the predominant FA, there appears to be a higher similarity between P. martia martia and P. serratus. The eggs of these species present similar levels of SFA, highly unsaturated (HUFA) and (n-3) FA but P. martia martia eggs have an extremely elevated MUFA and a low PUFA content. P. elegans has high levels of SFA, PUFA, HUFA and (n-3) FA. P. serratus and particularly P. martia martia eggs are characterised by a higher DHA:EPA ratio than P. elegans. The similarity between the FA profile of P. martia martia and P. serratus eggs may suggest that these 2 species are exposed to more comparable environmental condi- tions than P. elegans. As for the utilisation of FA classes during embryonic development, all species showed the same trend—MUFA were found to be the major energetic fuel during embryonic devel- opment while SFA and HUFA seemed to be conserved. A steady decrease in total lipids, particularly tri- (TAG) and diacylglycerol (DAG), and FA contents was noted in the 3 species. The utilisation of these lipid classes during the incubation period was comparatively low in P. martia martia and P. ele- gans in relation to P. serratus eggs. This may suggest a higher dependence of the newly hatched larvae of P. martia martia and P. elegans on their lipid reserves and has been interpreted as an adaptation to the early life history of these species, during which there might be a reduced availability of food.

FATTY ACID PROFILE OF PALAEMON SERRATUS (PALAEMONIDAE) EGGS AND LARVAE DURING EMBRYONIC AND LARVAL DEVELOPMENT USING DIFFERENT LIVE DIETS

Palaemon serratus (Pennant, 1777) is a shrimp with a high market value. It can be extensively produced in salt marshes with good survival rates, and it takes a reasonable period (8–10 months) to attain marketable size. For these reasons, it seems to have a good aquaculture potential. However, little is known about the nutritional requirements of this species, especially at the larval stages, and this may impose constraints to its successful rearing. This paper describes the changes occurring in the fatty acid profile of four developmental stages of Palaemon serratus eggs, newly hatched Zoea I larvae, and Zoea I starved for 24 and 48 hours, with the purpose of assessing larval fatty acid requirements. We also studied the effects of eight diets composed of microalgae (Chlorella sp. and Isochrysis galbana), rotifer (Brachionus plicatilis) and non-enriched or enriched brine shrimp (Artemia franciscana) nauplii on the fatty acid profiles of P. serratus postlarvae. Analysis of the P. serratus eggs revealed a high PUFA and HUFA content, which confirms their nutritional importance. The best results, in terms of postlarval fatty acid profile, were achieved with a diet of Artemia nauplii enriched with Protein Selco®, followed by a diet of B. plicatilis, Artemia nauplii, and Isochrysis galbana. The results from the present study are compared with survival and growth data from a previous study, and it is concluded that Protein Selco® appears to be the best Artemia enrichment product for the larval rearing of P. serratus.

Effects of environmental parameters on the oxygen consumption of four marine invertebrates: a comparative factorial study

The oxygen consumption curves of two decapod crustaceans (Palaemon serratus, Penaeus monodon) and two prosobranch molluscs (Trunculariopsis trunculus, Nassarius mutabilis) have been detected in the entire pO2 interval from 0 to 160 mmHg, under different conditions of temperature and salinity. From the experimental curves, physiological parameters such as the initial oxygen consumption velocity, the Q 10 values and the oxygen independence indices have been measured. The latter parameters have been obtained using normalised plots which allow their better evaluation. The effects of temperature, salinity and oxygen partial pressure on the oxygen-consumption features have been studied using a factorial experimental plan which allows measurement of the effects of each experimental variable as well as the effects of synergistic interactions between different variables.

Comparative feeding behaviour of Penaeus kerathurus (Forskål, 1775) (Crustacea, Penaeidae) and Palaemon Serratus (Pennant, 1777) (Crustacea, Palaemonidae) during larval development

Aspects of larval feeding of two autochthonous species of shrimp, Penaeus kerathurus (Forskål, 1775) and Palaemon serratus (Pennant, 1777), were studied. For P. kerathurus, feeding rates on Chlorella sp. and Isochrysis galbana Parke were determined at 3 different concentrations, during the protozoeal stage, and on Artemia franciscana Kellog at 4 different densities, during the mysis stage. The selectivity between Brachionus plicatilis Müller and Artemia franciscana nauplii was tested experimentally and the Ivlev selectivity index was calculated at the mysis stage. For Palaemon serratus Zoea III, V and VII, feeding rates on newly hatched A. franciscana nauplii, on metanauplii enriched during 24 hours in Protein Selco– and on starved metanauplii were determined. The Ivlev selectivity index was also calculated. The results revealed that Penaeus kerathurus and Palaemon serratus larvae have a negative selectivity for B. plicatilis. It is also suggested that the optimal density of A. franciscana for the mysis stage of P. kerathurus is around 10 nauplii mL–1. Finally, it was shown that the use of enrichment products leading to a very high lipid content of the prey may reduce their consumption rate.

Voltage dependence of the [Ca2+]ioscillations system, in the Mg2+-stimulated oocyte of the prawn Palaemon serratus

By voltage-clamp technique and simultaneous [Ca2+]imeasurements, we studied the modifications, induced by changes in membrane voltage, in the pattern of the [Ca2+]ioscillation period, displayed by the Mg2+-stimulated oocyte of the prawn Palaemon serratus. When the Mg2+-stimulated oocytes were voltage clamped at 0mV, they developed a [Ca2+]isignal with a more pronounced oscillatory pattern than that obtained on unclamped oocytes. Indeed, they displayed a first peak followed by a series of sharp [Ca2+]itransients and a prominent [Ca2+]ioscillatory plateau. By contrast, oocytes voltage clamped at − 60mV showed a first peak followed by a stable high [Ca2+]ilevel forming a long continuous plateau devoid of oscillations. By using caged InsP3, we established that the ER InsP3receptor is not voltage sensitive. Paradoxically, we showed the voltage sensitivity of the Mg2+receptor–signal transduction system which is more reactive to Mg2+ions at − 60mV than at 0mV. Using different calmodulin inhibitors of the PM CA pump such as trifluoperazin (100μM), W-7 (50μM) and calmidazolium (50μM), we suppressed the [Ca2+]ioscillatory pattern in oocytes voltage clamped at 0mV. From these results we propose that this special voltage-dependent oscillatory system could be regulated by a significant involvement of the electrogenic PM CA pump.

Fatty Acid Profile of Palaemon Serratus (Palaemonidae) Eggs and Larvae During Embryonic and Larval Development Using Different Live Diets

Abstract Palaemon serratus (Pennant, 1777) is a shrimp with a high market value. It can be extensively produced in salt marshes with good survival rates, and it takes a reasonable period (8–10 months) to attain marketable size. For these reasons, it seems to have a good aquaculture potential. However, little is known about the nutritional requirements of this species, especially at the larval stages, and this may impose constraints to its successful rearing. This paper describes the changes occurring in the fatty acid profile of four developmental stages of Palaemon serratus eggs, newly hatched Zoea I larvae, and Zoea I starved for 24 and 48 hours, with the purpose of assessing larval fatty acid requirements. We also studied the effects of eight diets composed of microalgae (Chlorella sp. and Isochrysis galbana), rotifer (Brachionus plicatilis) and non-enriched or enriched brine shrimp (Artemia franciscana) nauplii on the fatty acid profiles of P. serratus postlarvae. Analysis of the P. serratus eggs reve...

Ultrastructure of the microsporidian Inodosporus octospora (Thelohaniidae), a parasite of the shrimp Palaemon serratus (Crustacea, Decapoda).

A parasite of the muscle of the shrimp Palaemon serratus has been examined by light and electron microscopy. Development occurs among myofibrils and induces ultrastructural alterations of the muscle fibers causing white discoloration. This microsporidian is characterized by uninucleate, later diplokaryotic and di-diplokaryotic meronts. The mother cell develops by rosette-like budding into 8 uninucleate sporoblasts, each containing 3 tape-like filaments attached to the wall that is enclosed in a persistent sporophorous vacuole. Each sporoblast gives rise to a uninucleate spore that possesses 3 elongated tape-like filaments attached to the spore wall, like spore tails. The morphological characters of the spores, redescribed in the present study, suggested that the spores belonged to Inodosporous octospora. The possibility that in the future members of Inodosporus sp. may be considered a new parasite group is discussed.

Mercury chloride induces changes in the Mg 2+-stimulated membrane currents in oocytes of the prawn Palaemon serratus

In the prawn Palaemon serratus, seawater Mg 2+ ions trigger oocyte activation events in the absence of spermatozoon. The effect of mercury chloride on the conductance of unactivated prawn oocytes and the functioning of K + Ca and Na + Ca channels sequentially involved in the electrical response of prawn oocytes stimulated with external Mg 2+ was examined. In unactivated oocytes, 20 μM Hg 2+ induced a significant increase in membrane conductance after 15 min of incubation. Moreover, micromolar amounts of Hg 2+ ions (1–20 μM) affected, in both a dose- and voltage-dependent manner, the functioning of Ca 2+-dependent K + channels implicated in the first phase of the Mg 2+-induced electrical response of prawn oocytes. Treatment of oocytes with 5 and 10 μM Hg 2+ ions significantly diminished the maximal value of this initial Mg 2+-triggered outward K + current, while 20 μM Hg 2+ completely inhibited this response after 20 min of incubation. Maximal treatments of 10 and 20 μM Hg 2+ greatly increased the inward current involved in the second phase of the Mg 2+-induced electrical response of prawn oocytes, consequently inducing an increase in membrane conductance. This final increase in conductance elicited by Hg 2+ ions reflects a change in the selectivity of Ca 2+-dependent Na + channels.

Modelling estuarine Crustacea population fluctuations in response to physico-chemical trends

Regular samples (generally every 2 wk) of 6 estuarine crustacean species, Carcinus maenas, Liocarcinus holsatus, Crangon crangon, Palaemon longirostris, Palaemon serratus and Gammarus spp. (mainly G. zaddachi ), were taken over a 12 yr period from the cooling water intake screens of West Thurrock power station on the Thames estuary, UK. Additionally, comparative data sets for abiotic variables (freshwater flow, salinity, temperature, dissolved oxygen, pH, suspended solids, total nitrogen) were collected for the same time period. The comprehensive nature of the time series, and accompanying suite of variables, allowed the construction of statistical models for the trends in population abundance of the 6 species using multiple linear regression techniques. Statistically significant models were constructed for C. maenas, C. crangon and Gammarus spp., accurately predicting annual, and longer term, fluctuations in abundance. All models had strong seasonal components, although for C. maenas temperature was the only physico-chemical variable with significant explanatory power. The importance of temperature as a controlling variable for the species was reinforced by the inclusion of an instrumental variable to simulate a threshold temperature for foraging activity. The optimal value was found to be 8°C. C. crangon was found to be positively correlated with dissolved oxygen, but showed a slight decline in abundance over the time period. There was no significant relationship with either salinity or temperature, variables previously suggested as being important. Gammarus spp. abundance had 2 significant explanatory variables (temperature and salinity) but also demonstrated a large decrease in population size with time. L. holsatus and P. serratus are summer-occurring species, so were recorded too infrequently to adequately capture seasonal dynamics. Despite the long time series, no significant model was possible for P longirostris abundance (non-normal residuals), which has been suggested previously as having a strong relationship with salinity. The results of the study provide the first significant multiple linear regression models that accurately predict estuarine crustacean abundance. Whilst these models are useful for helping to understand variability in the Thames, it will be interesting to determine whether populations in other estuaries demonstrate relationships with similar suites of physico-chemical parameters.

The Effect of the Stimulation Regime on Palaemon serratus Tail Muscle Energy Metabolism

The evolution of phosphometabolites was determined in the abdominal muscle of a crustacean Palaemon serratus during intermittent electrical stimulation at 1, 2 and 4 Hz and during natural escape behavior. The changes in AMP, IMP, phosphomonoesters, adenylate energy charge and ATP/ADP ratio were not affected by the frequency of electrical stimulation. On the contrary, changes in ATP, ADP and sum of adenylates depended on the stimulation protocol: degradation of ATP and accumulation of ADP were not significantly different after electrical stimulation at 2 and 4 Hz as compared to manual stimulation, but differed from the 1 Hz stimulation protocol values. The sum of adenylates decreased similarly after 2 and 4 Hz stimulation and manual protocols. The different exercise protocols did not produce any changes in AMP and IMP accumulation, ATP/ADP ratio and A.E.C. After manual stimulation, the phosphomonoester and phosphoarginine concentrations were similar to the variations observed in the all electrical stimulation protocols, while the Pi levels were similar to the variations observed in the 4 Hz stimulation protocol only. The NMR index decrease was significantly higher after the manual and 4 Hz stimulation protocols.

Ecology of Sepiola Atlantica (Mollusca: Cephalopoda) in the Shallow Sublittoral Zone

The ecology of the sepiolid Sepiola atlantica in Firemore Bay, Loch Ewe, on the west coast of Scotland was investigated by beam trawling surveys. Low densities of this species were present in the shallow sublittoral zone of the sandy bay. A size range of 4–21 mm dorsal mantle length (DML) was obtained, with no significant differences detected between the mean sizes of males and females. Males reached gonadal maturity slightly earlier and at a slightly smaller size than females. Sepiola atlantica was present in the bay in each of the months in which sampling took place suggesting a resident population, the structure of which varied considerably. Juveniles were found over a prolonged period of the year but peak recruitment (animals of 4–10 mm DML) was in May and July. Animals <4 mm DML were not caught and no egg masses were found in the trawls. In aquarium conditions, S. atlantica fed on live crustaceans such as mysids, Crangon crangon and Palaemon serratus, although Corophium volutator, an estuarine crustacean not normally found in the marine sandy bay, was the most accepted food.

Short term cadmium intoxication of the shrimp Palaemon serratus: Effect on adenylate metabolism

1. 1. Shrimps were exposed for 96 hr to various concentrations of cadmium under laboratory conditions. The LC 50 was around 4 ppm Cd in water, which corresponded to 0.180 μg/g wet weight of cadmium in tail muscles. 2. 2. The effect of various concentrations of cadmium on adenylates was analyzed in tail muscles: At subletal cadmium concentrations, no variation of ATP, ADP and of the adenylate sum occurred, while the AMP concentration began to decrease from 0.06 ppm. At the LC 50, the ATP, ADP and AMP concentrations dropped acutely, the ATP/ADP ratio increased acutely. The apparent equilibrium constant of the adenylate kinase reaction increased significantly from 2 ppm Cd, indicating an impairment in energetic metabolism. Cadmium intoxication did not influence the value of the adenylate energy charge.

Locomotor Activity Patterns and Feeding Habits in the Prawn Palaemon Serratus (Pennant, 1777) (Decapoda, Palaemonidae) in the Alfacs Bay, Ebro Delta, Spain

AbstractDiel activity rhythms of the prawn Palaemon serratus from Alfacs Bay, Ebro Delta, Spain, were studied under laboratory conditions by time-lapse video recording. The activity pattern showed endogenous rhythmicity of a circadian period with maximum activity at night. The feeding habits of P. serratus were studied using the frequency-of-occurrence method and the points method. The food of this species mainly consists of molluscs and crustaceans, and the remains of gastropods, amphipods, isopods, bivalves, mysids, copepods, and decapods were identified. The remaining items consisted of cnidarians, polychaetes, ophiuroids, plant material, sand, and unidentified organic debris. Results indicate that P. serratus is a predator of benthic invertebrates rather than a scavenger or detritus feeder. Diet composition changes with the size of the prawn.

Amylase polymorphism in crustacea decapoda: electrophoretic and immunological studies

Alpha-amylase polymorphism was studied in 40 species of crustaceans belonging to four infraorders of Decapoda. Specific activities of alpha-amylases from hepatopancreas extracts of the same species were also measured. Very low specific activities were measured for Carcinus, Munida, Nephrops and Palinurus, whilst high activities were measured for shrimps and crabs. Amylases from one species of each of the four infraorders of Decapoda were purified by affinity chromatography. Very few differences in the specific activities of the pure enzymes were detected. The amylase content of crude extracts ranges between 0.1% of total protein, from the hepatopancreas in Carcinus maenas and Eupagurus bernhardus, to 1% Penaeus vannamei and Procambarus clarkii. The apparent molecular weight, determined by denaturating electrophoresis, was 55 kDa for Eupagurus and Procambarus amylases but only about 30 kDa for Carcinus and Penaeus amylases. Using immunodiffusion, rocket immunoelectrophoresis and enzyme inhibition with antibodies against Palaemon serratus α-amylase, we have shown that all the Decapod α-amylases are immunologically related but that they are different from those of Copepods, Bacillus or pig pancreatic amylases. The use of these data for phylogenetic analysis is discussed.

Use of ESR spectroscopy for the detection of irradiated Crustacea

AbstractFrozen whole tail sections of pink shrimp (Pandalus montagui), tiger prawn (Penaeus monodon), king prawn (Penaeus plebejus) and Mediterranean crevette (Palaemon serratus) were defrosted overnight and either irradiated the following day with doses of 1, 3 and 5 kGy or left unirradiated. Following irradiation the samples were stored for 0, 7,14 or 21 days at 1°C after which the cuticle was removed, freeze‐dried and ground prior to derivation of the electron spin resonance (ESR) spectra. The shape of the ESR signals derived from the irradiated cuticle of the four species were not identical. Subtraction of an average control spectrum from each species from that induced in the corresponding irradiated samples resulted in the isolation of a number of free radical peaks, the heights of which were measured and the sum of the values used as a measure of signal intensity. Both the irradiation dose and length of storage had a highly significant effect on signal intensity. The signal derived from the cuticle of the Mediterranean crevette was the most stable. The isolated radiation‐induced signals from all four species given 3 and 5 kGy were detectable in samples stored at 1°C for at last 14 days.

Seasonality of caridean decapod and mysid distribution and movements within the Severn Estuary and Bristol Channel

Mysids and caridean decapods are a significant proportion of the biomass within the Bristol Channel and Severn Estuary and key members of the marine food web in this estuarine system. Annual patterns of abundance at Hinkley Point Power Station of the mysids Praunus flexuosus, Schistomysis spiritus, Noemysis integer, Mesopodopsis slabberi and Gastrosaccus spinifer and of the carideans Pasiphaea sivado, Palaemon serratus, Pandalus montagui, Crangon crangon and C. allmani are examined. Using population age structures and sex ratios, the patterns of seasonal migration and recruitment are discussed.

Seasonality of caridean decapod and mysid distribution and movements within the Severn Estuary and Bristol Channel

Mysids and caridean decapods are a significant proportion of the biomass within the Bristol Channel and Severn Estuary and key members of the marine food web in this estuarine system. Annual patterns of abundance at Hinkley Point Power Station of the mysids Praunus flexuosus, Schistomysis spiritus, Noemysis integer, Mesopodopsis slabberi and Gastrosaccus spinifer and of the carideans Pasiphaea sivado, Palaemon serratus, Pandalus montagui, Crangon crangon and C. allmani are examined. Using population age structures and sex ratios, the patterns of seasonal migration and recruitment are discussed.