Hematopoietic neoplasia inMya arenaria: Prevalence and indices of physiological condition

A field survey of hematopoietic neoplasia (Hn) in the soft shell clamMya arenaria (L.) was undertaken using an immunoperoxidase diagnostic technique. Monthly collections ofM. arenaria were made at two sites: Little Buttermilk Bay and New Bedford Harbor, both in Buzzards Bay, Massachusetts, USA, from May 1986 to October 1987. Clams were diagnosed for leukemia and analyzed for soft-tissue dry weight, condition index, and carbon and nitrogen content of the soft tissue. Prevalence of leukemia inM. arenaria exhibited a seasonal fluctuation with a maximum prevalence in fall (September to October) and a minimum prevalence in early summer (March to July). A second maximum peak in late winter (January to March) was observed at one site. Leukemia primarily affected clams that were 3 to 4 yr post-settlement. Lower prevalence levels were observed in both younger and older clams. LeukemicM. arenaria with advanced stages of the disease, were in poorer physiological condition based on dry weight of the soft tissue, condition index, and carbon content of the tissue. Nitrogen metabolism appeared to be unimpaired. Significant differences were observed between the two sites with respect to prevalence of Hn and the physiological condition of clams. Differences in disease prevalence between the two sites may be the result of unknown environmental factors that facilitate initiation of the disease or, that compromise the defense mechanisms of the clams.     

Correlations between physiological responses of four aquatic plant species and river water quality

The Jiushanwai channel is located in the Lucheng district of Wenzhou City, China. Four aquatic plant species (Canna indica, Cyperus alternifolius, Myriophyllum verticillatum, and Lythrum salicaria) were planted on floating-beds constructed in a north-south layout along this channel. Five sites were sampled during spring, summer and autumn. The physiological characteristics (content of chlorophyll and soluble protein, activity of peroxidase and catalase) of the plants and the corresponding water quality were determined and correlations between these indices were analysed. The physiological indices of the plants and water quality changed regularly at the five sampling sites. Myriophyllum verticillatum was the most sensitive species to water quality changes, whereas Lythrum salicaria was least sensitive. Of the physiological indices examined, soluble protein content was most sensitive to water quality changes. The physiological indices of M. verticillatum are deemed to be most suitable to indicate river water quality.     

Morphological variation of Mytilus edulis and Mytilus trossulus in eastern Newfoundland

Allopatric populations of Mytilus species show distinct shell morphology which may be due to genetic and/or environmental effects. Sympatric populations of Mytilus species show similar shell morphology which may be due to hybridization eroding morphological differences and/or the influence of common environmental conditions. The present study examined shell morphology and shell shape from 16 sites in eastern Newfoundland where M. edulis L. and M. trossulus Gould coexist in common environments with limited hybridization. Shell morphology was based on measurements of eight characters, and shell shape was quantified by elliptic Fourier analysis of shell outlines. Significant differences were observed between species for both shell morphology and shell shape across 16 sites sampled. The relatively small differences in morphology and shape between the species were probably due to exposure to common environments rather than hybridization. Shell shape for M. edulis was more eccentric compared to M. trossulus which was more elongated. Shell shape analysis of a range of size classes at one site showed a change from an eccentric to an elongated shape going from the smaller to the larger size classes. Both species showed a similar trend, with the larger M. edulis more eccentric and the larger M. trossulus more elongated. Received: 17 July 1998 / Accepted: 6 January 1999     

Recovery of benthic communities at Macquarie Island (sub-Antarctic) following a small oil spill

Intertidal communities at Macquarie Island (sub-Antarctic) were re-evaluated seven years after a small oil spill resulting from the grounding of the “Nella Dan”, and six years after the first assessment of biological impact. Sampling was conducted to evaluate community structure in three zones of the exposed rocky shore (upper red, kelp, and lower red) and in samples of Durvillaea antarctica holdfasts. There were no significant differences between the community structure in oiled and control locations in any of the three shore zones, but holdfast macrofaunal communities at oiled sites still showed evidence of impact. Holdfast community-structure in samples from heavily oiled sites showed moderate levels of recovery, with increased abundances of species which were considered sensitive to the oiling in the first post-impact studies and decreased abundances of opportunistic polychaete and oligochaete worms. In contrast, samples collected from the moderately oiled location at Secluded Bay showed little evidence of recovery. Holdfasts at this site were filled with sediment containing traces of diesel oil, and the macrofaunal community was dominated by opportunistic worms. This study clearly indicates that even small incidents of anthropogenic perturbation can have long-lasting consequences for marine communities at Macquarie Island. Received: 23 July 1997 / Accepted: 5 February 1998     

Adaptations of wild populations of the estuarine fish Fundulus heteroclitus to persistent environmental contaminants

Many aquatic species, including the estuarine fish Fundulus heteroclitus (mummichogs), adapt to local environmental conditions. We conducted studies to evaluate whether highly exposed populations of mummichogs adapt to toxic environmental contaminants. These fish populations are indigenous to an urban estuary contaminated with persistent and bioaccumulative contaminants (dioxin-like compounds, or DLCs) that are particularly toxic to the early development of fish. We conducted laboratory challenge experiments to compare mummichog embryos and larvae from reference sites and this highly contaminated site [New Bedford Harbor (NBH), Massachusetts, USA] for their sensitivity to DLCs. While there was variation in DLC-responsiveness within each group, fish from NBH were profoundly less sensitive to DLCs than reference fish. Specifically, concentrations of DLCs similar to those measured in NBH-collected mummichog eggs were lethal to reference embryos. Further, DLC-responsiveness was inherited and independent of maternal contaminant contributions. These findings are consistent with the conclusion that DLC contamination in NBH has contributed to the selection of fish that are resistant to the short-term toxic effects of these environmental-contaminant exposures. This adaptation may be a critical mechanism by which fish populations persist in this highly contaminated site. Further evaluation of this ecosystem may provide important information concerning the direct and indirect consequences of this “unnatural” selection. Received: 12 July 1998 / Accepted: 16 January 1999     

Annual cycles of phytoplankton community-structure and bloom dynamics in the Neuse River Estuary, North Carolina

The spatiotemporal distributions of major phytoplankton taxa were quantified to estimate the relative contribution of different microalgal groups to biomass and bloom dynamics in the eutrophic Neuse River Estuary, North Carolina, USA. Biweekly water samples and ambient physical and chemical data were examined at sites along a salinity gradient from January 1994 through December 1996. Chemosystematic photopigments (chlorophylls and carotenoids) were identified and quantified using high-performance liquid chromatography (HPLC). A recently-developed factor-analysis procedure (CHEMTAX) was used to partition the algal group-specific chlorophyll a (chl a) concentrations based on photopigment concentrations. Results were spatially and temporally integrated to determine the ecosystem-level dynamics of phytoplankton community-constituents. Seasonal patterns of phytoplankton community-composition changes were observed over the 3 yr. Dinoflagellates reached maximum abundance in the late winter to early spring (January to March), followed by a spring diatom bloom (May to July). Cyanobacteria were more prevalent during summer months and made a large contribution to phytoplankton biomass, possibly in response to nutrient-enriched freshwater discharge. Cryptomonad blooms were not associated with a particular season, and varied from year to year. Chlorophyte abundance was low, but occasional blooms occurred during spring and summer. Over the 3 yr period, the total contribution of each algal group, in terms of chl a, was evenly balanced, with each contributing nearly 20% of the total chl a. Cryptomonad, chlorophyte, and cyanobacterial dynamics did not exhibit regular seasonal bloom patterns. High dissolved inorganic-nitrogen loading during the summer months promoted major blooms of cryptomonads, chlorophytes, and cyanobacteria. Received: 12 September 1997 / Accepted: 12 December 1997     

No apparent genetic basis to demographic differences in scarid fishes across continental shelf of the Great Barrier Reef

 Two species of parrot fish, Scarus frenatus and Chlorurus sordidus, are known to exhibit demographic and life-history differences across the continental shelf of the northern Great Barrier Reef (GBR). DNA sequences from the mitochondrial (mt) control region were analysed to determine whether there were genetic differences between the populations from the mid- and outer-shelf reefs. Analysis of molecular variance (AMOVA) indicated high levels of gene exchange for both species at a local scale between reefs on mid- and outer continental shelf positions (20 km apart) and at a broader scale along the length of the GBR province (>1000 km apart). There was no evidence to suggest that local differences in scarid life-history characteristics on the northern GBR have a genetic basis. Rather it appears more likely that phenotypically plastic responses to prevailing social and environmental conditions explain differences in the life-history characteristics of both taxa. However, analysis of genetic variation and historical demography revealed striking differences between the two species. S. frenatus haplotypes differed from one another at relatively few nucleotide sites (mean = 3.30), and the pairwise mismatch distribution suggested this species has undergone a population expansion within the limit of the resolution of the marker. C. sordidus haplotypes, however, differed from one another at a number of sites (mean = 7.67). Mismatch distribution analysis suggested that the population size of this species has remained at equilibrium over time. These patterns could also reflect differences in the metapopulation sizes or generation times between taxa. Some of the implications for fisheries management are discussed. Received: 28 January 2000 / Accepted: 9 July 2000     

Larval paternity and male reproductive success of a broadcast-spawning gorgonian, Plexaura kuna

Male reproductive success of the broadcast-spawning gorgonian, Plexaura kuna Lasker, Kim and Coffroth, 1996, was measured in June 1994 and June and July 1995 at two sites in the San Blas Islands, Panamá in order to determine the environmental and biotic factors affecting individual reproductive success. Developing embryos were collected in the field during natural spawning events, and paternity determined using randomly amplified polymorphic DNA markers. Analyses of F₁ progeny from defined laboratory matings established that the markers were inherited in Mendelian fashion, and allowed the determination of the zygosities of the markers. P. kuna is clonal, but male reproductive success was not strictly proportional to clone size. Proximity to females appeared to have a greater effect on male reproductive success than clone size, and on both reefs the most successful male clone was the one closest to the spawning female clone. Current direction and transport of gametes by eddies explained variation in paternity assignments between nights. Clonal propagation allows clones to grow and spread toward each other, and may enhance male reproductive success. Received: 1 April 1997 / Accepted: 11 February 1998     

Biomonitoring of polychlorinated byphenyls contamination in the supralittoral environment using the sandhopper Talitrus saltator (Montagu)

We evaluated the use of Talitrus saltator as biomonitor of polychlorinated byphenyls (PCBs) contamination of the supralittoral zone of Mediterranean sandy shores, an area not yet investigated about the presence of these pollutants. Twenty of 22 PCB congeners analysed were detected and quantified in sand and sandhoppers' samples collected in 6 different sites along the Tyrrhenian coast of Central Italy. Among the congeners analysed, PCB 153 and PCB 138 were the most abundant both in amphipods and sand samples and, regarding the congener pattern analysis, hexa-, hepta- and penta-PCBs were the most abundant congeners in sandhoppers. Though hydrophobic compounds, such as PCBs, bind strongly to sand and sediments, PCB concentrations were higher in T. saltator than in the sand revealing a good ability of this species to accumulate this class of contaminants. The concentration of each PCB congener recorded in tissues of sandhoppers showed significant differences among sampling sites revealing a good ability of these species to accumulate PCBs at different concentrations depending on the contamination levels of the sampling site. Therefore, our results suggest the possible utilisation of T. saltator as a biomonitor of PCB contamination of the supralittoral zone of Mediterranean sandy shores.     

Plasticity of social organization in a forest ant species

We manipulated availability of food and nesting sites in one population of the forest ant Myrmica punctiventris. The manipulations produced significant changes in relatedness structure, reproductive allocation, and response to hierarchical selection. Food availability appeared to have a consistently stronger influence on these aspects of social organization than did availability of nesting sites. We interpret our experimental results in light of observed differences between populations, and discuss implications for kin selection dynamics. Received: 30 July 1998 / Accepted after revision: 31 October 1998     

Comparison of the osmoregulatory capabilities of two portunid crabs,Callinectes sapidus and C. similis

An investigation of the osmoregulatory capabilities of two portunid crabs, Callinectes sapidus and C. similis, was conducted to determine if their differences in distributional patterns were reflected in their capacity to adjust physiologically to changes in salinity. After acclimation to 5, 20 and 35 S, measurements of hemolymph and muscle concentrations of Na⁺, Cl^- and K⁺ and muscle-free amino acids indicated that C. sapidus is a better osmoregulator at low salinity than C. similis, while both species osmoregulate equally well at high salinity. This difference in osmoregulatory capacity corresponds well with their distribution in coastal-plain estuaries.This research was supported under agreement (49-7)-5 between the National Marine Fisheries Service and the Energy Research and Development Administration.Communicated by M.R. Tripp, Newark     

Deep-sea caging of the mussel Mytilus galloprovincialis: Potential application in ecotoxicological studies

We experimented with caging the Mediterranean mussel (Mytilus galloprovincialis) at various depths for 69 d to measure basic physiological parameters, histological response and bio-accumulation of contaminants in a deep-sea contaminated area. In preliminary experiments, we demonstrated, under artificial pressure conditions, the ability of mussels Mytilus galloprovincialis to tolerate rapid immersion (at a speed of up to 120 m min^?1). In situ experiments were performed using submerged lines enabling mussels to be maintained at depths ranging of 40–1550 m with survival rates ranging from 80 to 38%, respectively. No significant differences in condition indexes were observed between treated and control specimens. However, histological observations demonstrated a clear reduction in thickness of the digestive epithelium with increasing depth exposure. By determining the contaminants in caged mussels, we found the following values for chromium accumulation: 27.4 μg g^?1 dry weight at 580 m depth and 9.8 μg g^?1 dry weight at 1550 m. Selected stations were located downstream of an industrial effluent at 420 m. The biological and environmental consequences of deep-sea contamination demonstrate the suitability of caged mussels for monitoring contaminant accumulation.     

Evaluation of chlorophyll fluorescence, in vivo spectrophotometric pigment absorption and ion leakage as biomarkers of UV-B exposure in marine macroalgae

The photosynthetic fluorescence ratio F_v:F_m, in vivo absorption spectra and ion leakage were evaluated as biomarkers of ambient and elevated UV-B (280 to 320 nm) exposure of the intertidal alga Enteromorpha intestinalis (Chlorophyta) and the sublittoral alga Palmaria palmata (Rhodophyta). Measurements of thallus growth were also used to assess adverse biological effects. Ambient and elevated UV-B significantly inhibited photosynthesis in both species. It was shown that the F_v:F_m ratio is a sensitive, non-specific general biomarker of UV-B exposure in both species. Moreover, the in vivo absorption of what was tentatively identified as chlorophylls a and b as well as phycoerythrin and/or carotenoids, phycoerythrobilin and phycocyanin decreased in a dose-response dependent manner and was associated with a decrease in growth rate in P. palmata. The intertidal alga E. intestinalis showed a greater degree of tolerance to UV-B exposure. These results indicate that changes in the F_v:F_m ratio together with reductions in in vivo pigment absorption could provide an early quantitative warning of the detrimental effects of UV-B in marine macroalgae. Received: 16 May 1997 / Accepted: 16 July 1997     

Spatial variation in population dynamics in a colonial ascidian (Botryllus schlosseri)

Recent interest in the dynamics of marine invertebrate populations has focused largely on taxa with an open population structure. However, in many colonial taxa with limited larval dispersal, settlers may be locally derived. Consequently, dynamics may vary among sites that are separated by relatively short distances. This study explored spatial variation in temporal dynamics of colonial ascidians (Botryllus schlosseri Pallas) inhabiting five sites distributed along a ≈ 17-km temperature and phytoplankton gradient in the Damariscotta River estuary, Maine, USA. Settlement and population densities and sexual reproductive status were assayed throughout the summer seasons of 1996 and 1997. Sexual reproduction and larval settlement commenced earlier in the summer in up-river populations, which subsequently underwent a seasonal population explosion that was much smalier in down-river populations. Two peaks in settlement density up-river (in early July and early September) suggest that colonies there may have completed two sexual generations, in contrast to a single generation at down-river sites. Similar spatial variation is expected among populations of other taxa with limited larval dispersal when they are distributed across environmental gradients. Published online: 18 September 2002     

Use of the digestive gland of the oyster Crassostrea rhizophorae (Guilding, 1828) as a bioindicator of Zn,Cd and Cu contamination in estuarine sediments (south-east Brazil)

This study demonstrates the accumulation of Zn, Cd and Cu in the digestive gland of the oyster Crassostrea rhizophorae in response to the contamination of sediments and discusses the potential use of this specific organ in monitoring metal contamination in tropical areas. Sediment and oyster samples were collected from coastal Rio de Janeiro sites with different levels of human impact: Sepetiba Bay, Guanabara Bay and the Paraty coast. Metal concentrations were measured using inductively coupled plasma optical emission spectrometry (ICP OES). Significant statistical differences (p<0.001; p<0.05) were observed for Zn and Cd concentrations in the digestive gland; the highest Zn concentrations were found at Sepetiba, followed by Guanabara and Paraty. The highest digestive gland Cd concentrations were found at Paraty, followed by Sepetiba and Guanabara. These concentrations were proportional to those found in the sediments. There was no significant difference (p>0.05) in Cu among the sampling sites. The highest digestive-gland Cu concentration was also found at Sepetiba, followed by Guanabara. The biosediment accumulation factor indicated a gradient of sediment contamination for Zn and Cd. The digestive gland of C. rhizophorae can be a potential indicator of trace metal contamination in sediments from tropical estuarine environments.     

浑河流域野生鲫鱼卵黄蛋白原基因表达

为揭示浑河流域水环境内分泌干扰物对水生态的潜在风险,利用兼并引物扩增获得鲫鱼卵黄蛋白原(Vtg)和核糖体蛋白L-7(RPL-7)基因部分碱基序列(分别为825和450bp),建立以RPL-7为内参基因、定量鲫鱼Vtg基因表达的实时定量逆转录聚合酶链反应(qRT-PCR)方法,并将该方法用于定量浑河野生鲫鱼肝组织Vtg基因表达分析。结果显示:与上游对照点(S1)相比,7月下游各点(S4～S8)雄鱼、S4和S6点雌鱼肝组织的VtgmRNA表达水平皆显著升高(P<0.05);11月在雄鱼中未检出VtgmRNA的有效表达,雌鱼也仅在S2和S3点的表达水平升高(P<0.05)。研究表明,浑河流域野生鲫鱼尤其是在7月明显受到了环境雌激素类物质的影响。另外,qRT-PCR方法能够灵敏检测出鲫鱼Vtg基因表达的时空差异。     

RNA:DNA ratios of the hydrothermal-vent vestimentiferans Ridgeia piscesae and R. phaeophiale indicate variations in growth rates over small spatial scales

The ratio of RNA to DNA (RNA:DNA) was used to assess the relative growth rates of the hydrothermal vent vestimentiferans Ridgeia piscesae Jones and R. phaeophiale Jones. This biochemical indicator of growth is especially valuable when actual growth rates are difficult to measure. Tubeworms were collected from five hydrothermally active sites along the Juan de Fuca Ridge, in the Northeast Pacific Ocean in the summers of 1984 and 1986. We found significant variation in RNA:DNA among Ridgeia spp. from the five sites which was not due to size of the tubeworms or to a species-specific difference. Instead, differences in RNA:DNA were related to site of collection. Mean RNA:DNAs of 2.1 and 3.9 for R. piscesae from two sites were significantly different from each other, but not from that of tubeworms from a third site (mean=2.9). Similarly, mean RNA:DNAs of 2.3 and 4.5 for R. phaeophiale from two sites were significantly different. These patterns in RNA:DNA may reflect differences in growth rates arising from variation in environmental factors over spatial scales as small as 2 m.     

Differences in life-cycle traits of<Emphasis Type="Italic"> Calanus finmarchicus</Emphasis> originating from 60°N and 69°N,when reared in mesocosms at 69°N

Two different Calanus finmarchicus (Gunnerus) cohorts originating from 60°N (Bergen) and 69°N (Tromsø) were investigated in equal environmental conditions to study their different physiological responses to the same environment. A two-plus-two-bag mesocosm study was carried out between March and July 1998, in Håkøybotn, Tromsø, in order to determine development and mortality rates of the two parallel cohorts of C. finmarchicus. For practical reasons, the cohort from Bergen was incubated 10 days earlier than the Tromsø cohort. Consequently, they were exposed to elevated food conditions as compared to the Tromsø cohort. A high initial mortality among the Bergen cohort could clearly be ascribed, by genetic discrimination, to "contamination" with C. helgolandicus. After this initial mass mortality, the mortality was constantly 0.03-0.04 day^у. In cohorts starting from naupliar stage I, there was no significant difference in development or growth, the median development time (NI-CIV) differing by only 7 days (~6%). The difference in development time can be explained to a large extent (~4 days) by temperature differences. This is substantiated with model simulations using a physiological model developed for C. finmarchicus. There was a time lag in incubation between the two cohorts, resulting in elevated temperature during incubation of the Tromsø cohort. A fraction of both cohorts differentiated sexually at stage CV, with males differentiating before females. Females from both cohorts produced eggs, but specific egg production differed significantly (P>0.001, t-test). This was supported by elevated RNA:DNA ratio in females from the Bergen cohort. Both cohorts demonstrated quite similar development and physiological growth rates and, consequently, are considered to belong to the same genetic population inhabiting the Norwegian Shelf. The study demonstrates that C. finmarchicus is capable of adaptation to changes in environment and, thereby, demonstrates a significant physiological plasticity.     

Phenotypic flexibility in response to environmental salinity in the euryhaline crab Neohelice granulata from the mudflat and the saltmarsh of a SW coastal lagoon

This study constitutes a first attempt to investigate intraspecific differences in osmoregulatory capacity and digestive and metabolic responses at the biochemical level in relation to hyper- and hypo-regulation in a single species of estuarine crab inhabiting contrasting habitats within a same intertidal area. We compared hemolymph osmolality, key digestive enzymes, glycemia and energy reserves in Neohelice granulata (Dana in Proc Acad Nat Sci Philadelphia 5:247–254, 1851) from the mudflat and saltmarsh of Mar Chiquita coastal lagoon (37°32′/37°45′S-57°19′/57°26′W) under a wide range of salinities (6–60 psu). Individuals from both sites exhibited high and similar osmoregulatory capacity, but while in individuals from mudflat low and high salinities affected lipase activity in hepatopancreas and triglycerides in muscle, in crabs from saltmarsh, high salinities affected glycogen in anterior gills. Low salinity differentially affected free glucose in anterior gills. The results suggest the occurrence of intraspecific distinct digestive and metabolic adjustments in relation to osmoregulatory responses and habitat.