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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The reproductive activity and the physiological state of the calanoid copepods Calanus helgolandicus and Calanoides carinatus were investigated off the coast of NW Spain during autumn to evaluate the effect of short food resources on both populations. Phytoplankton biomass was low, and neither phytoplankton size distribution nor composition was suitable to support high reproductive rates. Accordingly, egg production rates (EPR) were much lower than maximum rates for both species, pointing to food limitation. The reproductive index (RI), which represents the proportion of females with mature gonads, was <50% at each of the three zones into which the sampling area was divided (coast, shelf and ocean). Potential recruitment rates were very low except at some nearshore stations, where the highest concentrations of chlorophyll-a (Chl-a), diatoms, dinoflagellates and large cells were found. EPR of C. helgolandicus and C. carinatus were correlated with phytoplankton biomass and unaffected by temperature. Phytoplankton carbon ingestion explained ca. 50% of the variability in EPR for both species. At most of the stations, herbivory was insufficient to cover the carbon requirements for reproduction and respiration, so females probably fed on heterotrophic prey to meet their demands. However, given the low fecundity observed, this omnivorous diet did not seem to be optimum for reproduction, and a severe food limitation is thus suggested. Furthermore, the high C/N values measured point to a notable lipid storage, but given the low EPR found, lipid reserves were probably invested into female maintenance rather than into gonad maturation. C. helgolandicus and C. carinatus populations did not mirror phytoplankton biomass distribution, but they correlated well when considering only copepodites V (CV). The CV could be preparing for the overwintering, storing lipid reserves to ensure a successful diapause, and they could also be advected by the poleward current detected during the study. Females showed a diel feeding rhythm, with highest ingestion rates during night. From our results, it follows that C. helgolandicus and C. carinatus females did not perform diel vertical migrations. We suggest that this behaviour is likely due to the food-limiting conditions, which make it more advantageous to remain at the surface during daytime. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Previous studies have demonstrated that macroalgae from Brittany (France) contain products with antifouling activity against marine bacteria, fungi, diatoms, seaweeds and mussels. Little is known regarding the ecological function of these compounds and insufficient attention has been paid to evaluating the possible temporal variation in antifouling activity. Studies of chemical defenses in both terrestrial and marine organisms suggest that organisms vary widely in the production of chemical defenses associated with physical (temperature, light) and biological (e.g. grazing pressure) factors, season and geographical location. The present study aimed to investigate the antifouling activity of crude extracts of monthly collections of the brown alga, Bifurcaria bifurcata, against two marine bacteria, Cobetia marina and Pseudoalteromonas haloplanktis, and cypris larvae of the barnacle, Balanus amphitrite. The toxicity of the extracts was determined with a B. amphitrite nauplius assay. The antimicrobial activity of the extracts was found to be subject to seasonal variation, with the highest level of activity recorded from samples collected between April and September. Results of the anti-settlement experiments showed that the extracts of B. bifurcata (when tested from 0 to 100 @mg/ml) can be divided into three groups on the basis of their minimum inhibitory concentrations (MICs): (1) extracts from plants collected from September to March reduced settlement at nontoxic concentrations (50-100 @mg/ml); (2) extracts from plants collected from April to July (which were the most active extracts) reduced settlement significantly when tested at >5 @mg/ml, but were toxic at 100 @mg/ml; (3) the extract prepared from plants harvested in August was inhibitory at >25 @mg/ml, but was toxic at 100 @mg/ml. Toxicity tests on nauplii showed that LC"5"0 values of samples from the September to March collections were >100 @mg/ml, demonstrating that they were nontoxic to nauplii. In contrast, samples obtained from the April to August collections were toxic to nauplii; the most toxic ones being from algae collected in May (LC"5"0=55.6 @mg/ml) and in June (LC"5"0=38.3 @mg/ml). The antifouling activity of extracts thus reached a peak in summer corresponding to maximal values for water temperature, light intensity and fouling pressure. It remains to be investigated whether this activity has an ecological role in the alga. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Previous studies conducted on the continental shelf in the Southeast Bay of Biscay influenced by Gironde waters (one of the two largest rivers on the French Atlantic coast) showed the occurrence of late winter phytoplankton blooms and phosphorus limitation of algal growth thereafter. In this context, the importance of dissolved organic phosphorus (DOP) for both algae and bacteria was investigated in 1998 and 1999 in terms of stocks and fluxes. Within the mixed layer, although phosphate decreased until exhaustion from winter to spring, DOP remained high and phosphate monoesters made up between 11 to 65% of this pool. Total alkaline phosphatase activity (APA, V"m"a"x) rose gradually from winter (2-8 nM h^-^1) to late spring (100-400 nM h^-^1), which was mainly due to an increase in specific phytoplankton (from 0.02 to 3.0 nmol @mgC^-^1 h^-^1) and bacterial APA (from 0.04 to 4.0 nmol @mgC^-^1 h^-^1), a strategy to compensate for the lack of phosphate. At each season, both communities had equal competitive abilities to exploit DOP but, taking into account biomass, the phytoplankton community activity always dominated (57-63% of total APA) that of bacterial community (9-11%). The dissolved APA represented a significant contribution. In situ regulation of phytoplanktonic APA by phosphate (induction or inversely repression of enzyme synthesis) was confirmed by simultaneously conducted phosphate-enrichment bioassays. Such changes recorded at a time scale of a few days could partly explain the seasonal response of phytoplankton communities to phosphate depletion. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The mole crab Emerita talpoida migrates with the tide in the swash zone of sand beaches. A circatidal rhythm in vertical swimming underlies movement, in which mature male crabs show peak swimming activity 1-2 h after the time of high tides at the collection site. In addition, there is a secondary rhythm in activity amplitude, in which crabs are maximally active following low amplitude high tides and minimally active following high amplitude high tides. The present study determined the phase response relationship for entrainment of the circatidal rhythm with mechanical agitation and whether the cycle in activity related to tidal amplitude could be entrained by a cycle in the duration of mechanical agitation at the times of consecutive high tides. After entrainment with mechanical agitation on an orbital shaker, activity of individual crabs was monitored in constant conditions with a video system and quantified as the number of ascents from the sand each 0.5 h. Mechanical agitation at the times of high tide, mid-ebb and low tide reset the timing of the circatidal rhythm according to the timing relationship to high tide. However, mechanical agitation during flood tide had no entrainment effect. In addition, a cycle in duration of mechanical agitation entrained the rhythm in activity amplitude associated with tidal amplitude. Both rhythms and entrainment effectiveness over the tidal cycle may function to reduce the likelihood of stranding above the swash zone. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Changes in in situ xanthophyll activity were compared in symbiotic dinoflagellates within the reef-building corals, Montastraea faveolata, Montastraea annularis, and Acropora cervicornis over a daily light cycle from morning until dusk on a shallow (4 m) patch reef. Examination of algae collected from the tops and sides of M. faveolata and M. annularis revealed typical inter-conversion of diadinoxanthin and diatoxanthin, with the greatest abundance of diatoxanthin noted by the mid-morning to afternoon, correlating to daily reduction in the effective quantum yield of photosystem II (@DF/F"m') for the respective colony location. A. cervicornis had the highest proportion of diatoxanthin relative to the total xanthophyll pool, yet it also displayed the least amount of total daily xanthophyll cycling which did not correlate well with patterns of change in @DF/F"m'. For intraspecific comparisons, no significant difference in daily xanthophyll activity was noted between the different locations in each coral species, while differences in @DF/F"m' were detected. In some cases temporal trends in nonphotochemical quenching (NPQ) of chlorophyll fluorescence did not match patterns in xanthophyll activity when peak xanthophyll cycling tended to lag behind the immediate light intensity measured in the mid-morning at some colony locations. Genetic characterization of symbionts using polymerase chain reaction-denaturing gradient electrophoresis of the rDNA internal transcribed spacer 2 region (ITS2) revealed that M. faveolata and M. annularis hosted the type B1 symbiont at all locations, while the type A3 symbiont was noted throughout A. cervicornis. Results indicate that while xanthophyll cycling appears to be largely a ubiquitous phenomenon in symbiotic dinoflagellates, the degree of cycling can be quite different between coral species at the same depth and that other biochemical pathways for daily photoprotection may predominate some host-symbiont combinations. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Salt marsh communities are known for well-defined species zonation patterns. Lower limits of plant growth are thought to be set by an ability to tolerate anoxic sediments, but the physiological differences between species have not previously been examined. To investigate responses to anoxic sediments, several estuarine species were grown in greenhouse experiments to compare how respiratory processes were affected by flooding. Metabolic characteristics related to respiration and anoxia tolerance were studied in the emergent estuarine species Spartina alterniflora, S. anglica, S. densiflora, S. foliosa, S. alternifloraxS. foliosa hybrids, S. patens, and Distichlis spicata and compared to the inland species maize (Zea mays). All species showed a strong ability to respire anaerobically, indicating flooding tolerance. High intertidal marsh species had significantly higher root aerobic respiration enzyme activities compared to low intertidal species that may suggest lower aerobic demand in low marsh species. Some higher marsh species showed an apparent high sensitivity to sulfide that may be related to high cytochrome c oxidase activities. In contrast, the low marsh species S. alterniflora and S. anglica had lower aerobic respiration enzyme activities and a lower sensitivity to sulfide. Thus differences in aerobic demand and sulfide sensitivity may influence estuarine species zonation. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Maximum nitrate reductase (NR) activity was measured in two intertidal morphotypes of Zostera noltii (Hornem.) in Ria Formosa tidal lagoon, southern Portugal. The two morphotypes develop in the upper and lower limits of the intertidal meadows. The NR activity was measured using an in vivo method, without cell disruption. NR activity was 30-40 fold higher in leaves than in roots, which indicates that nitrate reduction is essentially made through the aerial part of the plant. The effects of assay temperature (5 ^oC steps, from 5 to 45 ^oC), pH (7, 8 and 9) and elevation (upper and lower intertidal) on leaf NR activity were tested in a factorial design (n=5). Both elevation and assay temperature had a significant effect on NR activity, but not pH. NR activity was always higher in the upper intertidal plants, at all temperatures. Activity peaks for upper and lower plants were, respectively, 6.12 @mmol NO"2^- g^-^1 DW 0.5 h^-^1 at 25 ^oC, and 3.30 @mmol NO"2^- g^-^1 DW 0.5h^-^1 at 35 ^oC. Further investigation on environmental factors concerning the intertidal environment must be developed, as they are probably responsible for the significant differences found between the values of NR activity in the upper and lower morphotype. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Root glutamine synthetase (GS; EC 6.3.1.2) activity was measured daily (0 to 4 days) for eelgrass (Zostera marina L.) plants held under continuous darkness rooted in sediments, continuous darkness without sediments, continuous light without sediments, and control light/dark cycle (Control L/D). Roots experiencing prolonged aerobiosis exhibited lower activity in vitro than controls, whereas roots experiencing prolonged anoxia exhibited increased activity. Plants held in darkness without sediments had activity intermediate between controls and anoxic roots. One-hour pretreatment of root extracts with ATP slightly reduced in vitro glutamine synthetase activity, whereas pretreatment with ADP and AMP increased activity ~50%. While glutamine synthetase activity increased with higher adenylate energy charge (AEC) in the reaction mixture, pretreatment of enzyme extracts at high adenylate energy charges decreased subsequent activity relative to pretreatment at lower energy charges. One-hour pretreatment with l-alanine (Ala) had little effect on enzyme activity. Pretreatment with l-glutamine (Gln), l-glutamate (Glu), and @c-amino butyric acid (GABA) increased activity ~75%. Incubation of excised roots under anoxic conditions for 24 h nearly doubled enzyme activity. However, addition of cycloheximide to anoxic root incubations lessened or prevented the increase in activity. It appears that enhanced glutamine synthetase activity following periods of root anoxia results from interactions with metabolites that fluctuate between aerobic and anoxic conditions, particularly adenylates, and from de novo synthesis of glutamine synthetase or some other protein synthesis-dependent process. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The occurrence, characteristics and response to environmental salinity of alkaline phosphatase (AP) activity were studied in chela muscle of the euryhaline crab Chasmagnathus granulatus from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). Chela muscle exhibited a levamisole-insensitive and a levamisole-sensitive AP activities with distinct characteristics. Levamisole-insensitive activity appeared to be maximal at pH 7.7, whereas levamisole-sensitive AP activity was similar with the range of pH 7.4 to 8.0. Both activities at pH 7.7 exhibited a Michaelis-Menten kinetics (K"m=0.789 and 1.416 mM, respectively). I"5"0 for levamisole-sensitive AP activity was about 12 mM. Levamisole-insensitive and levamisole-sensitive AP activities were differentially affected by temperature. Levamisole-sensitive AP activity was quite sensitive to temperature, exhibiting a peak at 37 ^oC but being low at 5 to 30 ^oC and 45 to 60 ^oC. Both activities were inhibited by Cu^2^+. At 1.0 mM Cu^2^+, levamisole-insensitive AP activity was inhibited about 82% whereas levamisole-sensitive AP activity was almost completely inhibited. Levamisole-insensitive AP activity appeared to be sensitive to environmental salinity. In crabs acclimated to low salinity (10%%) this activity was lower than in 35%% salinity. The response to environmental salinity suggests that levamisole-insensitive AP activity could be a component of muscle regulatory mechanisms at the biochemical level secondary to hyperregulation of C. granulatus. The possible physiological roles and functional relationship of AP activity with Na^+/K^+ ATPase in muscle are discussed.are discussed. ... Read more

Product Description
This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The occurrence, characteristics and response to environmental salinity and dopamine of alkaline phosphatase (AP) activity were studied in chela muscle of the euryhaline crab Cyrtograpsus angulatus from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). Chela muscle exhibited a high AP activity with a Michaelis-Menten kinetic (K"m=1.21 mM). AP activity was strongly inhibited by EDTA (I"5"0=2.26 mM). AP activity appeared to be sensitive to environmental salinity. In crabs acclimated to low salinity (10%%) AP activity was lower than in 35%% salinity. Upon an abrupt change to reduced salinity a short-term decrease of AP activity occurred, concomitant with the transition to hyperregulation. Furthermore, AP activity appeared to be under hormonal control since it was inhibited ''in vivo'' by 10^-^4 M dopamine. The response to both environmental salinity and dopamine suggests that AP activity could be a component of muscle regulatory mechanisms at the biochemical level secondary to hyperregulation of C. angulatus. The possible functional relationship of AP activity with Na^+/K^+ ATPase in muscle is discussed. ... Read more

Product Description
This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Arylsulfatase from Artemia salina exists in at least two forms (AS I and AS II). The paper presents characterization of the AS II form of the arylsulfatase. The enzyme was able to hydrolyze p-nitrocatechol sulfate (pNCS) as well as ascorbate sulfate. It exhibited maximum activity at temperature of 50 ^oC and was stable for 2 h at 4-10 ^oC. Optimum pH shifted from 6.2 at 4 mM pNCS (substrate) to 4.8 at 20 mM pNCS. The enzyme displayed linear kinetics. AS II arylsulfatase exists in two molecular forms (349 and 460 kDa) composed of identical subunits with molecular mass of 53 kDa. Sulfite and phosphate ions were the most potent inhibitors of the enzyme. Cyanide proved to be a weak inhibitor. Sulfate and low concentrations of silver ions had no effect on the enzyme activity. Based on the above results, modifications in the assay for determination of enzyme activity are proposed. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In oligotrophic waters the light spectrum is mostly blue, and therefore the physiological and biochemical responses to blue light occurring in the coral tissue and in the symbiotic algae are important. Examination of the wavelength dependence of two free radical scavenger enzyme activity revealed an increase in activity in the blue light range (440-480 nm) compared to the red (640-680 nm) in the full visible light (400-700 nm) range. These data show for the first time the relationship between the action spectra of photosynthesis and the activity of two main antioxidant enzymes in the symbiotic coral Favia favus. It was found that in the animal (host) the enzyme response to the spectral distribution of light was higher than that of the zooxanthellae, probably due to accumulation of free radicals within the host tissue. Furthermore, we found that the activity of these enzymes is affected in nature by the length of the day and night, and in the laboratory, by the duration of the illumination. Changes in the pigment concentrations were also observed in response to growth under the blue region and the whole PAR spectrum, while fluorescence measurements with the fast repetition rate fluorometer (FRRF) showed a decrease in the sigma cross section and a decrease in the quantum yield also in the blue part of the spectrum. These changes of scavenger enzymes activity, pigment concentration and fluorescence yield at different light spectra are vital in acclimatization and survival of corals in shallow water environments with high light radiation. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Inorganic phosphorus (P"i) is important in the regulation of many carbon and nitrogen metabolic processes of plants. In this study, we examined alterations of phosphomonoesterase activity (PA; both alkaline and acid) in a submersed marine angiosperm, Zostera marina, grown in P"i non-limiting conditions under elevated temperature and/or nitrate enrichment. Control plants (ambient water-column NO"3^- <2.5 @mM, with weekly mean water temperatures between 26.5-27.0 ^oC based on a 20-yr data set in a local embayment) were compared to treated plants that were exposed to increased water-column nitrate (8 @mM NO"3^- above ambient, pulsed daily at 0900 h), and/or increased temperature (ca. 3 ^oC above weekly means) over eight weeks in late summer-fall. Under both nitrate regimes, increased temperature resulted in periodic increased leaf and root-rhizome tissue carbon content, and increased acid and alkaline PA activities (AcPAs and AlPAs, respectively). There was a positive correlation between AlPA and AcPA activities and sucrose synthase activities in belowground structures, and a negative correlation between AlPA activities and sucrose concentrations. There were also periodic changes in PA partitioning between carbon source and sink tissues. In high-temperature and high-nitrate treatments, AcPAs significantly increased in leaves relative to activities in root-rhizome tissues (up to 12-fold higher in aboveground than belowground tissues in as little as 3 weeks after initiation of treatments). These responses were not observed in control plants, which maintained comparable AcPA activities in above- and belowground tissues. In addition, AlPA activity was significantly higher in leaf than in root-rhizome tissues of plants in high-temperature (weeks 3 and 6) and high temperature combined with high nitrate treatments (week 8), relative to AlPA activities in control plants. The observed changes in PAs were not related to P"i growth limitation, and may allow Z. marina to alter its carbon metabolism during periods of increased carbon demand/mobilization. This response would make it possible for Z. marina to meet short-term P requirements to maximize carbon production/allocation. Such a mechanism could help to explain the variability in PA activities that has been observed for many plant species during periods when environmental P"i exceeds requirements for optimal growth. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Caulerpa racemosa (Forsskal) is a green marine alga which spreads from tropical to warm-water regions. Due to having invasive capacity C. racemosa var. cylindracea is a well-known biological pollution in Mediterranean Sea. One of the most important secondary metabolites of C. racemosa is Caulerpenyne (CPN). In the present study, antiproliferative and apoptotic effects of C. racemosa var. cylindracea extract and purified CPN on two well-known neuroblastoma cell lines, SHSY5Y and Kelly, are investigated. The antiproliferative and, additionally, newly attributed apoptotic effects of both C. racemosa var. cylindracea extract and purified CPN on SHSY5Y and Kelly cell lines have been shown in the present study. IC"5"0 values are 0.59+/-0.06; 1.06+/-0.23 g wet alga/methanol and 5.64+/-0.09; 6.02+/-0.09 @mM CPN for C. racemosa var. cylindracea extract and purified CPN on SHSY5Y and Kelly cell lines, respectively. Percentages of apoptotic cells of SHSY5Y and Kelly in 0, 0.1 and 1 @mM CPN conditions were 1.00+/-0.71, 3.00+/-0.71 and 49.40+/-3.78, 39.60+/-6.19 and 78.00+/-2.74, 69.40+/-3.78, respectively. In conclusion, the present study shows the antiproliferative effect of C. racemosa var. cylindracea extract and newly attributed apoptotic effects of C. racemosa var. cylindracea this extract. Compared to other alkylating anticancer drugs, CPN and also C. racemosa var. cylindracea extract might be considered as an alternative native source of antitumor drugs. Inasmuch as both C. racemosa extract and CPN have shown both antiproliferative and apoptotic effects on SHSY5Y and Kelly cell lines, the CPN and CPN derivatives might be considered as multifunctional agents in cell metabolism. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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In vitro antimicrobial screening of nine marine sponges (Porifera) and two seaweeds, collected from south east coast of India, against selected clinical isolates of bacteria and fungi was conducted in this study. Methanolic extracts of all the marine organisms demonstrated activity against one or more of microbes tested. Sigmadocia carnosa was the most active exhibiting a broad spectrum antimicrobial activity against each of the microbe tested with the exception of Fusarium species. Contrary to this, the genus Echinogorgia did not show any detectable bactericidal activity but, Echninogorgia reticulata was weakly fungicidal against Rhodotorula species and E. compecta against Fusarium and Nocardia species. Considerable antibacterial activity was exhibited by Haliclona cribricutis and Chrotella australiensis against Klebsiella species and Vibrio cholerae, respectively. Petrocia testudinaria showed equally good activity against the bacterium V. chlorae and the fungus Cryptococcus neoformans. The sponges Callyspongia fibrosa, Ircinia species and the seaweed Stoecheospermum margilatum are totally inactive against fungi. The extracts showing good antimicrobial activity are undergoing further analysis to identify the active constituents. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The short-term osmoregulatory capacity of sea bass (Dicentrarchus labrax) larvae and juveniles at consecutive developmental stages was evaluated by an analysis of drinking rates and whole-body and branchial Na^+/K^+ ATPase activity. The effect of acute salinity stress on those parameters was assessed from hatching to the juvenile stage. Drinking rate normalised to body weight (DR"b"w) decreased throughout postembryonic development. DR"b"w was not affected by salinity in yolk sac larvae. However, significant differences were observed in older larvae and in juveniles submitted to hypo- and hyperosmotic challenges. Post yolk sac larvae and juveniles always drink, but at a lower rate in hypoosmotic media compared to hyperosmotic media. A correlation was established between DR"b"w and blood osmolality during the postembryonic development of the sea bass. Na^+/K^+ ATPase specific and total activity in whole larval homogenates decreased from hatching to the 5-mm yolk sac larva stage and increased in 10-mm stage larvae. The enzyme specific activity in the gills, from post yolk sac larvae to juveniles, decreased whereas the total activity increased during the same period. Developing sea bass have a better capacity to cope with hypoosmotic than hyperosmotic media. ... Read more

Customer Reviews (1)

Return to Return to the River
This review is based on the 1965 hardcover edition of Haig-Brown's RTTR originally published in 1941.It's an interesting little book about salmon migration from the point of view of the fish.Lots of terrific pencil/charcoal illustrations.The author gives the salmon an identity without Disney-fying the poor creature.(Written today, the author and subsequent movie producer probably would have turned the fish into a talking cartoon.)Also, don't let yourself be put off by a few multi-syllabic scientific insect names.And the bits of human dialog might seem awkward and dated (the author is better at thinking like a fish!).But it's not a tough read.Frankly, a motivated junior high school student could probably handle it.Read this book if:

· You enjoy Portland, the Columbia River and the Pacific Northwest.You'll get a kick out of recognizing familiar places and rivers and scenery.

· You are into salmon behavior or fishing or environmental causes.However, I suspect there are lots of more up-to-date, sophisticated treatments of these subjects.

· Your dad had a copy of the book on his bookshelf the entire time you were growing up and, years later, you "borrowed" it from your mom and have hung onto it along with other bits and pieces that remind you of dear ol' dad and you finally cracked it open one day when looking for something to read.

OK, maybe that last reason only applies to me...unless the spine of this book was filed on the shelf behind your dad's recliner next to a copy of Goren's Bridge Complete(the things you remember!) and formed part of the backdrop for many curfew-and-car-keys negotiations.

A fun read for lots of reasons.
... Read more

Product Description
A 20-page book about life in the ocean, with four fold-down scenes showing a coral reef, the Antarctic ocean, the continental shelf and the 'dark depths'. There are four pop-up models: great white shark, killer whale, sperm whale and giant squid - which are kept in a re-sealable pack at the back of the book. The book also contains press-out figures to go with each scene. ... Read more