Mechanics and energetics of swimming in the small copepodAcanthocyclops robustus (Cyclopoida)

High-speed films of swimmingAcanthocyclops robustus were used to test a crustacean swimming-model based on numerical analysis of thrust production. Predicted body velocities and jump distances were usually within 75% of those observed. Most of the thrust which propels.A. robustus is produced by movements of the 2nd, 3rd, and 4th thoracic swimming legs, with only small contributions from the first thoracic swimming legs. A model analyzed without the first antennae suggested that the antennae do not produce significant thrust. The leg and antennal movements could be described with trigonometric equations (cosine curves), but were best described by polynomial fits of position vs time data from the films. Patterns of swimming velocity varied among four episodes that were modeled, and followed differences in swimming-leg motions. Model results for the small (cephalothorax length = 0.6 mm) cyclopoidA. robustus and those which have been reported for the large calanoid copepodPleuromamma xiphias and other swimmers indicate that mechanical efficiency (30%) does not scale with body size, whereas jump distance (one body length), proportion of thrust generated by hydrodynamic added mass (70%), and net cost of transport,C _p (40 to 109 cal g^–1 km^–1) do.Please address all correspondence and requests for reprints to G. Gust at the University of South Florida, St. Petersburg     

Patterns of organic osmolytes in two marine bivalves, Macoma balthica, and Mytilus spp., along their European distribution

Patterns of nine intracellular free amino acids (FAA), which are utilized as organic osmolytes for salinity-induced cell volume regulation in marine osmoconformers, were compared in five Macoma balthica populations and seven Mytilus spp. populations along their European distribution. Three types of FAA patterns were classified within both taxa: a northern Baltic type, a southern Baltic type and an Atlantic/Mediterranean type which mainly differ regarding the share of alanine and taurine. Differences are discussed in relation to habitat salinity and population genetics. Along a salinity gradient, the total size of the intracellular FAA pool did not differ between sympatric M. balthica and Mytilus spp., and was significantly correlated with habitat osmolality in a range from 70 to 600 mmol kg⁻¹ H₂O (oligohaline to mesohaline) in both bivalves. In M. balthica, this correlation was mainly based on significant correlations of alanine (15–100 mmol kg⁻¹ DW), glycine (30–100 mmol kg⁻¹ DW) and taurine (0–70 mmol kg⁻¹ DW) with habitat osmolality. In Mytilus spp., only glycine (25–100 mmol kg⁻¹ DW) and taurine (4–180 mmol kg⁻¹ DW) were significantly correlated with habitat osmolality. The concentration of alanine was three times lower in Mytilus spp. than in M. balthica and did not correlate with habitat osmolality. Within a habitat osmolality range from 600 to 1,100 mmol kg⁻¹ H₂O (mesohaline to marine) the concentration of FAA remained constant in both taxa. It is suggested that under marine conditions additional organic osmolytes must become more important for cell volume regulation in Macoma and Mytilus.     

Primary production of Posidonia oceanica in the Mediterranean Basin

Primary production of the marine phanerogam Posidonia oceanica (Linnaeus) Delile was measured by lepidochronological analyses at 22 sites in the Mediterranean Sea (Corsica, France, Italy, Sardinia and Turkey), between 1983 and 1992, to determine spatial and temporal variations. Leaf production (blade and sheath) ranged from 310 to 1 540 mg dry wt shoot^–1 yr^–1, depending on site and depth. Rhizome production ranged from 24 to 120 mg dry wt shoot^–1 yr^–1 (6% of average leaf production). At some sites the results obtained by lepidochronological analysis were consistent with earlier results obtained by classic methods (e.g. leaf-marking). While primary production per shoot (mg dry wt shoot^–1 yr^–1) displayed no significant differences between sites, primary production of the P. oceanica meadow (g dry wt m^–2 yr^–1) decreased with increasing depth at all sites studied. This decrease correlated with reduced density of the meadow (number of shoots per m²) with increasing depth. Past primary production was also extrapolated at three sites at the island of Ischia (Italy) for a period of 5 yr in order to determine interannual variations over a period of several years. While major variations were recorded for the surface stations (5 and 10 m depth), production remained stable at the deepest station (20 m depth). Given the large geographical scale of the study (location, depth range), it would appear that while P. oceanica production remains considerable, the values recorded in the literature on the basis of classical analyses (surface stations) represent maxima, and cannot be generalised for meadows as a whole.     

Cationic dye adsorption onto natural and synthetic zeolites in the presence of Cs+ and Sr2+ ions

Adsorption of diazine dye safranine O (SO) in the presence of Cs⁺ and Sr²⁺ ions was investigated onto natural and synthetic zeolites in order to predict competition of cationic organic species with their radionuclides, which are the main fission products released into the environment. Adsorption of SO was measured up to the 40th day and the surface-diffusion coefficients (D_s) were estimated by applying Nernst–Planck approximation based on a homogeneous-surface-diffusion model. The values of D_s were 10 times higher on natural zeolite than those of synthesized zeolite from fly ash (FA) under hydrothermal conditions. Similarly, distribution coefficients (K_D) were considerably higher on the clinoptilolite-type natural zeolite. The zeolitized product of FA is mainly composed of analcime and sodalite. SO adsorption on natural zeolite was not influenced by Cs⁺ and Sr²⁺ ions, but it decreased at high concentrations on synthetic zeolite. The higher influence of the Sr²⁺ ions on SO⁺ adsorption showed that they compete with each other for the same adsorption sites. These results suggested that natural zeolite cannot be used for remediation of wastewater polluted with Cs and Sr radionuclides in the presence of organic cations, whilst FA zeolite has a potential for Sr removal.     

Growth and longevity in the crustose red algaPetrocelis middendorffii

Petrocelis middendorffii is a non-calcareous encrusting red alga growing on rocks in the middle and upper intertidal zone. We have photographically followed the fate of 43 individual plants for periods up to 88 months at Waadah Island, near Neah Bay, Washington (USA). Growth is slow, with surface area increasing about 4% year^-1 for those individuals growing. Other plants were observed to decrease in total surface coverage, fragment, and eventually disappear. Plants on neighboring but not contiguous sample sites are not in synchrony, with some subpopulations increasing their total space coverage while others diminished theirs. Age estimates, based on a variety of growth interpretations, suggest that an average sized individual (123 cm²) will be from 25 to 87 years old. Recruitment and mortality rates appear low. The ecological traits ofP. middendorffii may be similar to those of other crustose heteromorphic benthic algae.     

Risk assessment of heavy metal contamination in shrimp farming in Mai Po Nature Reserve, Hong Kong

An ecological survey was carried out to determine the sediment concentrations of nutrients and heavy metals and bioaccumulation of heavy metals in fish and shrimp including tilapia (Oreochromis mossambicus×O. nilotica), grey mullet (Mugil cephalus), gei wai shrimp (Metapenaeus ensis) and caridean shrimp (Macrobrachium nipponensis) in the traditional tidal shrimp ponds (gei wais) of Mai Po Nature Reserve, Hong Kong. The sediments collected from the landward sites contained higher nutrient contents, as well as zinc (Zn), chromium (Cr), copper (Cu), nickel (Ni) and cadmium (Cd) than those collected from the seaward sites, but vice versa for lead (Pb) and mercury (Hg). However, the concentrations of all metals were exceptionally high in the two sites located outside the reserve, suggesting that waters from Deep Bay might be the possible source of metal contamination affecting the reserve. All metals studied seemed to accumulate in the viscera of fish. Body size was the determining factor for the accumulation of heavy metals in caridean shrimp and gei wai shrimp but not fish. Concentrations of the metals studied in tissues of grey mullet and gei wai shrimp were found to be safe for human consumption. Concentrations of Cr in tilapia whole body (0.68–1.10 mg kg⁻¹ wet weight) were close to or over the guideline value of 1 mg kg⁻¹ set by the Food Adulteration (Metallic Contamination) Regulations of Hong Kong. Tilapia flesh and small caridean shrimp collected from gei wais were contaminated by Cr and Pb but still fit for human consumption. Caution is required if large caridean shrimp is to be consumed in large amounts continuously because the concentration of Pb exceeded the maximum permitted concentration (6 mg kg⁻¹). The rather high Cr concentrations in tilapia whole body should not be overlooked as the fish will serve as a food source for migratory birds visiting the site.     

Residues of fluoroquinolones in marine aquaculture environment of the Pearl River Delta, South China

Concentrations and distributions of selected fluoroquinolones (norfloxacin, ciprofloxacin and enrofloxacin) in water, sediments and nine kinds of fish species collected from 6 sites in two marine aquaculture regions of the Pearl River Delta, China, were analyzed by using high-performance liquid chromatography with fluorescence detector (HPLC). The results showed that the concentrations of ciprofloxacin and enrofloxacin were below the limits of quantification (LOQ) in all water samples except for norfloxacin. Norfloxacin and ciprofloxacin concentrations ranged from 1.88 to 11.20 ng g⁻¹ dry wt, 0.76–2.42 ng g⁻¹ dry wt in sediments collected from the Dapeng’ao region (sites 1–3) and ranged from 2.31 to 4.75 ng g⁻¹ dry wt, 1.26–1.76 ng g⁻¹ dry wt in sediments collected from the Hailing Island region (sites 4–6), respectively. However, no enrofloxacin was found in all sediment samples. The three fluoroquinolones (FQs) were detected in all fish samples, and the concentrations were higher in liver tissues than those in muscle tissues. The levels of norfloxacin were higher than ciprofloxacin and enrofloxacin in both liver and muscle tissues. Among the nine marine fish species, Siganus fuscescens from Hailing Island had a significantly high level of norfloxacin in liver tissue (254.58 ng g⁻¹ wet wt), followed by Sparus macrocephalus (133.15 ng g⁻¹ wet wt) from Dapeng’ao, and the lowest value was Lutianus argentimaculatus (5.18 ng g⁻¹ wet wt) from Hailing Island. The obtained results of FQs in present study do not represent a risk to the human health in Guangdong coastal area, based on the maximum residue limits (MRLs) established by Chinese Government and the acceptable daily intake (ADI) recommended by the Food and Agriculture Organization and World Health Organization (FAO/WHO).     

Trace Metals in Fish and Crustaceans - Identifying Heavier Polluted Areas in the Ghanaian Continental Shelf

Abstract

The concentrations of four trace metals, namely copper, lead, cadmium and manganese, were determined in six fish species and three crustaceans collected from five sites spanning over 70% of the Ghanaian coastline.

Copper and lead were determined in Barracuda (Spraena spraena), the Ribbon fish (Trichiurus lepturus), the Sardine (Sardinella spp), the Sole (Cynoflossus senegalensis), the Sea Bream (Pagrus coupei) and the Soldier fish (Cynapastas marmuratus). Cadmium and manganese were analyzed in the Blue Crab (Callinectes sepidus), the Spiny lobster (Panilirus regius) and the edible shrimp (Crago septempinosus). Sampling sites included Takoradi, Elmina, Cape Coast, Accra and Tema.

Lead and copper in the fishes ranged 0.25-0.94 μgg^?1 fresh weight and 0.40-2.54 μgg^?1 dry weight (FW) respectively whilst cadmium and manganese in the crustaceans ranged 0.05-0.083 μgg^?1 FW and 0.554-1.404 μgg^?1 FW respectively.

The Barracuda accumulated the greatest amount of metals whilst the sardine accumulated the least. with the crustaceans, there was a significant difference between the amounts of the metals accumulated. the blue crab accumulated the greatest and the edible shrimp the least.

The analysis showed that: (i) there was a positive correlation between the metals bioconcentrated and the extent of pollution of the marine waters and (ii) along the Ghanaian Continental Shelf, the extent of pollution was of the increasing order as: Elmina = Cape Coast < Takoradi < Accra < Tema. Pollution of the marine waters could be minimized by control of flow of pollutants from land based activities.     

Polymorphism of mannose phosphate isomerase in North Sea and Baltic Sea populations of the amphipods Gammarus zaddachi and G. salinus

Genetic variation at the mannosephosphate isomerase (MPI) locus was examined in the euryhaline sibling species Gammarus zaddachi Sexton and G. salinus Spooner. Both crustacean amphipods share identical enzyme mobilities, following electrophoresis on vertical starch gels. The MPI locus turned out to be highly polymorphic; it is encoded by 6 alleles in G. zaddachi and 7 alleles in G. salinus. Geographic variation of allelic diversity was studied in samples from 9 G. zaddachi and 10 G. salinus populations, primarily obtained from Baltic Sea and North Sea sites. Patterns of inter- and intraspecific heterogeneity are described. Differences in allelic composition exist between Baltic and North Sea samples of G. salinus. In G. zaddachi, levels of polymorphism are higher in North Sea populations than in those from Baltic Sea areas. The significance of these findings is discussed in the light of previous biochemical genetic investigations on the population structure of the two amphipods considered.     

Patterns of mtDNA diversity in North Atlantic populations of the mussel Mytilus edulis

Patterns of (female) mitochondrial DNA diversity were investigated in the blue mussel Mytilus edulis. Mytilus edulis is a ubiquitous member of contemporary North Atlantic hard-substrate communities and well represented in studies of this region. Mytilus edulis was surveyed in North America and Europe, as well as mid-Atlantic sites in Greenland, Iceland, and the Faroe Islands. Mitochondrial DNA sequences revealed considerable population structure but no monophyly of haplotypes between any major regions. Coalescent analyses suggest that migration across the Atlantic Ocean has prominently been from North American source populations and that Greenland was colonized recently and exclusively from North America. In North America, there was support for two regional groups along the North American coastline. Surprisingly, we also found evidence of recombination between some Mytilus edulis and Mytilus galloprovincialis female mtDNA sequences, particularly in northern Europe. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. An erratum to this article can be found at     

The density and size distribution of Diadema antillarum in Dominica (Lesser Antilles): 2001–2004

Diadema antillarum populations at many Caribbean locations have failed to recover from a wide-spread mortality event during the early 1980s. Quantitative assessments of Diadema in Dominica have only recently begun and can now be put into a regional context. Diadema and benthic algae were monitored in 4-month intervals at six 100 m² sites, spread over a distance of 38 km, along the west coast of Dominica. Diadema density surveys began in July 2001, while algal cover was monitored as of November 2001. Mean densities of individual sites ranged from 0.81 m⁻² (SD=1.02) to 2.98 m⁻² (SD=1.33), and overall means increased from 1.50 m⁻² (SD=0.12) in 2001, to 2.00 m⁻² (SD=0.05) in 2004. The weak negative relationship observed between the Diadema density and macroalgal cover (R ²=0.25, P=0.0030), indicates that Diadema play a limited role in controlling macroalgal species. In contrast, the abundance of turf algae was positively related to low Diadema densities, yet this relationship becomes negative beyond a critical point between 2.0 and 3.0 Diadema per m² (R ²=0.25, P=0.0075). As of November 2001 size measurements of 100 randomly sampled urchins at each site were included in the surveys, resulting in overall mean test size diameters ranging between 5.54 cm (SD=1.55) and 6.00 cm (SD=0.96). The mean test size diameter per site ranged from 4.54 cm (SD=1.91) at Tarou Point in November 2003 to 6.77 cm (SD=0.83) at Salisbury November 2001. Across all sites except Tarou Point, the most commonly occurring Diadema sizes throughout this study were within 1 cm, in the range between 4.5 and 7.5 cm. It is unclear how this Dominica scenario fits into the context of the pathogen-induced mass mortality events of the 1980s because neither qualitative nor quantitative records exist for that time in Dominica. The recent increase in Diadema density may be a symptom of recovery from Hurricane Lenny. Given the indiscriminant local pressure (affecting herbivorous fishes as well as fish predators of Diadema) Diadema’s role as grazer of algal turfs is highlighted. On a regional scale, its stable population of reproductive size classes may serve as source of larvae for nearby downstream islands.     

Polycyclic aromatic hydrocarbons in household dust near diesel transport routes

A river-dredging project has been undertaken in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main roads. Ten stations along major thoroughfares were selected as the exposure sites for testing, while a small village located about 9 km from a main traffic route was selected as the control site. Levels of household dust loading at the exposure sites (60.3 mg/m²) were significantly higher than those at the control site (38.2 mg/m²). The loading (μg/m²) of t-PAHs (total polycyclic aromatic hydrocarbons) in the household dust at the exposure sites was significantly higher (P < 0.05) than was the case at the control site. The diagnostic ratios of PAHs showed that diesel emissions were the dominant source of PAHs at the exposure sites. The lack of a significant correlation between the concentrations of Fe and t-PAHs suggested that the t-PAHs in household dust might come from diverse sources. However, a significant correlation (P = 0.003) between the concentrations of Mo and t-PAHs implied that the most of the t-PAHs in the household dust might have resulted from diesel emissions. The lifetime cancer risks of BaP_eq from household dust exposure were markedly higher than those resulting from inhalation exposure.     

Trends in sediment metal concentrations in the River Avoca, South-East Ireland

Variation in sediment metal concentrations in the River Avoca, which is severely polluted by acid mine drainage (AMD) discharged from the abandoned sulphur and copper mines in Avoca, is reported. A survey of surface and subsurface sediments was repeated after seven years during exceptionally low flow conditions in 2001. The present study found that the reference (up-stream) site used in the original 1994 study was itself impacted by AMD, showing sediment metal enrichment by AMD to be greater than originally thought. The new reference site contained elevated Pb (570 µg g^–1) in the subsurface sediment due to abandoned Pb-Zn mines 25 km further upstream. Concentrations of Cu (43 µg g^–1), Zn (349 µg g^–1) and Fe (4.0%) were normal for uncontaminated rivers. All the downstream sites showed sediment metal enrichment arising from the AMD (Cu and Zn p < 0.001; Fe p < 0.01). Subsurface concentrations of metals immediately below the mixing zone were Cu 904 µg g–1 (sd 335), Zn 723 µg g–1 (sd 93), Fe 6.3% (sd 1.5) and Pb 463 µg g^–1 (sd 279). Monthly variation in metal concentrations at sites was not significantly different (p > 0.05). Although surface sediment metal concentrations were more variable, they followed similar trends to subsurface sediment. There were no significant differences in the subsurface sediment concentrations for either Cu or Zn over the period 1994 and 2001 immediately below the mines, although at the lowest site Zn had decreased by 35% over the period (p < 0.01). However there was a significant (p < 0.01) decrease over the period in the Fe concentration at all the impacted sites. This corresponds to a reduction in Fe concentration in the AMD and indicates that some remediation has occurred in the river since 1994.     

Settlement, recruitment and potential predators and competitors of juvenile echinoderms in the rocky subtidal zone

Recruitment patterns of marine invertebrates are affected both by settlement and early post-settlement events. This study examined the settlement and recruitment patterns of echinoderms at three sites in the rocky subtidal zone of Bocabec Cove, Bay of Fundy, Canada using artificial turf collectors and quadrats on the natural substrate. Potential predators were quantified at two of the sites along transects and in 1-m² quadrats. Both potential predators and competitors were quantified in 0.0625-m² quadrats. Settlement varied across sites (1.5–3 km apart) and two years of sampling (2004, 2005). The site of most potential settlement differed for the three groups of echinoderms: sea urchins (Strongylocentrotus droebachiensis), sea stars (Asterias spp.) and sea cucumber (Psolus fabricii). Settlement densities on the artificial turf collectors tended to be greater than the densities of settlers on the natural substrate. On the natural substrate, the only significant difference between densities of juveniles over time was that newly settled sea stars were found in July and were not found the following October. Large lobsters and carnivorous worms were potential predators with densities that varied between sites. Potential competitors that differed in abundance between sites were herbivorous gastropods and conspecifics for sea urchins; and carnivorous worms for sea stars. This study suggests that patterns of recruitment are either set up by patterns of settlement or by events during the first few weeks/months on the benthic substrate for these echinoderms.     

Trophic relationships among invertebrates at the Kairei hydrothermal vent field (Central Indian Ridge)

Exploration of hydrothermal vent systems in locations remote from well-studied sites allows ecologists to determine the degree of site-specific variation in trophic relationships among communities. A preliminary outline of the trophic structure of the Kairei hydrothermal vent community on the Central Indian Ridge (25°19.23′S; 70°02.42′E) is provided here, based on analysis of collections from an April 2001 expedition. Invertebrate biomass at Kairei is dominated by organic carbon with a δ¹³C isotopic value of about –13‰, due to the abundance of primary consumers (shrimp: Rimicaris aff. exoculata) and secondary consumers (anemones: Marianactis n. sp.) with this isotopic composition. Filamentous thiotrophic episymbionts on shrimp have been interpreted to be the major diet items of the shrimp and hence are the dominant primary producers within the community. Free-living autotrophic microorganisms are implicated as the dietary base for other invertebrate species. Four trophic groups are identified within the Kairei invertebrates based on carbon- and nitrogen-isotope ratios, but these groups do not always define discrete trophic levels. Ontogenetic shifts in diet are documented for R. aff. exoculata and brachyuran crabs (Austinograea n. sp.). Diets of symbiont-bearing mussels (Bathymodiolus aff. brevior) and two species of gastropods are isotopically constant throughout the range of sizes analyzed. There is a consistent but unexplained pattern of increasing nitrogen isotopic composition with increasing carbon isotopic composition in vent communities from geographically disjunct oceanic regions. Given the assumptions associated with interpretations of isotopic data, there remains a missing pool of carbon (presumably unsampled bacterial biomass) that contributes to the maintenance of the ¹³C- and ¹⁵N-enriched primary consumers in these ecosystems.     

Assessment of the impacts of municipal solid waste dumps on soils and plants

The study aimed at evaluating the impacts of open municipal solid wastes dumps on soil and vegetation near the main roads linking major cities in Nigeria. We hypothesised that the metals from the wastes exerted substantial impacts at the dump sites which affect the soil and plants. Data were analysed from five dump sites and five control sites. The result revealed that the effects of the heavy metals (HM) were significant and higher at the dump sites where their concentrations were far above the EU, and Canadian environmental quality permissible limits for agricultural soils and vegetation. In contrast with dump sites, a significant relationship (R²?=?0.70; p??Cr?>?Pb at both dump sites and control sites. Further study on the effects of more HM on soil and plant is recommended in the area. Recycling and bio-phytoremediation processes should also be introduced.     

Spatial variations in the N2O emissions and denitrification potential of riparian buffer strips in a contaminated urban river

Spatial variations in the N₂O emissions and denitrification potential of riparian buffer strips (RBS) in a polluted river were examined. The river received large pollutant inputs from urban runoff and wastewater discharge, resulting in impaired water quality in the river and downstream reservoir. The potential for nitrogen removal by RBS was evaluated by measuring in situ N₂O emission fluxes in static closed chambers and sediment denitrification potentials with acetylene inhibition techniques. The results showed that N₂O emission fluxes decreased from the upstream (16.39 μg/(m²·h)) to downstream (0.30 μg/(m²·h)) sites and from the water body to upland sites. The trend in decreasing N₂O emission fluxes in the downstream direction was mainly associated with sediment/soil textures (clay loam→sandy soil) and sediment/soil water contents and was also related to the vegetation along the RBS and nutrients in the sediments/soils. The correlation coefficient was highest (r=0.769) between the N₂O emission flux and sediment/soil water content. Sediment/soil denitrification potentials under N-amended and ambient conditions were higher (highest 32.86 mg/(kg·h)) for the upstream sites, which were consistent with in situ N₂O flux rates.     

Allozyme and mitochondrial DNA variation in yellowfin tuna (Thunnus albacares) from the Pacific Ocean

Samples of yellowfin tuna (Thunnus albacares) collected in 1991 and 1992 from the western, central and eastern regions of the Pacific Ocean were examined for genetic variability. Four polymorphic allozyme loci (ADA ^*, FH ^*, GPI-S ^* and GPI-F ^*) were examined in all samples and a fifth polymorphism (GDA ^*) was examined in western and central samples only. Samples were also screened for mitochondrial DNA variation following restriction analysis by two enzymes (BcII and EcoRI) detecting polymorphic cut sites. Eighteen mtDNA haplotypes were revealed, with an overall nucleon diversity of 0.678. A subset of individuals screened for eight restriction enzymes had an overall nucleon diversity of 0.724 and a mean nucleotide diversity per sample of 0.359%. No significant spatial heterogeneity was detected for alleles at the ADA ^*, FH ^*, GPI-S ^* and GDA ^* loci nor for the mtDNA haplotypes. Significant heterogeneity was detected for GPI-F ^*. At this locus, the two eastern samples (southern California and northern Mexico) were not significantly different from each other but were significantly different (P<0.001) from the five western/central samples (Philippines, Coral Sea, Kiribati, Hawaii-91 and Hawaii-92). GPI-F ^* 100 was the most common allele in western and central regions, GPI-F ^* 75 the most common in eastern samples.     

Effects of environmental hypercapnia on hemato-immunological parameters,carbonic anhydrase,and Na+, K+-ATPase enzyme activities in rainbow trout (Oncorhynchus mykiss) tissues

In this study, the effects of environmental hypercapnia on hemato-immunological parameters and the activities of respiratory enzymes such as carbonic anhydrase (CA) and Na⁺, K⁺-ATPase were investigated in rainbow trout (Oncorhynchus mykiss) tissues (gill, liver and kidney). Batches of 12 fish were exposed to 4.5 mg L^?1 (control) and 14 mg L^?1 CO₂. No mortalities occurred during the 14 days of the experimental period. Red blood cell (RBC), hemoglobin (Hb), and hematocrit (Ht) levels, and innate immune parameters such as nitro blue tetrazolium (NBT), lysozyme, and myeloperoxidase activities, and the melano-macrophage frequency were negatively affected by elevated CO₂ levels. Patterns of change in CA activity differed among the gill, liver, and kidney. Compared with the activities of CA in the control group, the CA enzyme was significantly stimulated at day 7 in the gill tissue, whereas it was stimulated at day 14 of the experiment in the liver tissue of fish exposed to 14 mg L^?1 CO₂ (P < 0.05). In contrast to the pattern of CA enzyme activities, the Na⁺, K⁺-ATPase enzymes were stimulated significantly in the liver after day 7 but inhibited in the kidney and gill (P < 0.05). These results suggest that a subchronic exposure to hypercapnia of rainbow trout tissues may lead to adaptive changes in the respiratory enzymes and negatively affects hemato-immunological parameters.     

Variability of stable isotopes and maximum linear extension in reef-coral skeletons at Kaneohe Bay, Hawaii

Stable-isotope and growth records of coral skeletons are often used to reconstruct tropical paleoclimate, yet few surveys have systematically examined the natural variability in coral skeletal ¹³C, ¹⁸O and maximum linear skeletal extension (MLSE) across depth. Here, interspecific, intraspecific, and geographical variations in coral skeletal ¹³C, ¹⁸O, and MLSE were examined in the corals Porites compressa, P. lobata, and Montipora verrucosa grown at 1.7, 5.0, and 8.3 m depth from August 1996 to March 1997 at The Point Reef and Patch Reef #41 field sites in Kaneohe Bay, Hawaii. Coral skeletal ¹³C values significantly decreased with depth and differed between species, but did not vary between field sites. ¹⁸O values were not significantly different across depth within a species, but did differ among species and field sites. High-resolution analysis of the intra-annual variation in skeletal ¹³C and ¹⁸O in P. compressa at 2.0 m depth confirms that these isotopes reflect changes in solar irradiance and temperature, respectively. Changes in MLSE across depth were consistent within, but highly variable among, species. Peak MLSE occurred at 1.7, 5.0, and 8.3 m for P. lobata, P. compressa, and M. verrucosa, respectively. Such interspecific variation in MLSE patterns may be attributable to one or more of the following: increases in zooplankton in the diet, changes in metabolic processes, or changes in growth form with depth. Overall, these results imply that natural inter- and intraspecific variability in coral skeletal ¹³C, ¹⁸O, and MLSE should be considered when interpreting and comparing coral-based tropical paleoclimate data from various coral species, depths, and field sites. Received: 6 October 1998 / Accepted: 8 July 1999