Effects of dietary and water-borne oil exposure on larval pacific herring (Clupea harengus pallasi)

Pacific herring (Clupea harengus pallasi) larvae were exposed either directly to the water-soluble fraction (WSF) of crude oil or indirectly via oil-contaminated prey (OCP) (Artemia salina) for <- 28 days, to determine the relative effects of diet and water as routes of contamination. Larvae were affected rapidly by 0·9 ppm WSF, which caused high larval mortality, reduced swimming ability and rapid reductions in feeding rates. Larval length was significantly reduced by 0·7 ppm WSF in 7 days and by 0·3 ppm WSF within 14 days. The WSF exposure also caused similar reductions in larval weights. Highly contaminated prey (6 ppm prey exposure) caused significant mortality, but surviving larvae appeared robust. The OCP did not affect swimming, feeding, or growth. Exposure of larvae was not significantly extended by OCP, which rapidly depurated WSF in clean water (98% in 1 day). Therefore, OCP is probably not an important source of low molecular weight petroleum contamination to larval fish in the marine environment.     

Relationships between sediment contamination and toxicity in San Francisco Bay

Sediment contamination and toxicity were monitored at 14 sites in San Francisco Bay between 1991 and 1996. Sediment contamination patterns were different in the major reaches of the Bay, and at each site. Several contaminants were consistently above concentrations previously associated with toxicity at most sites. Bulk sediment bioassays using the amphipod Eohaustorius estuarius and sediment elutriate bioassays using larval bivalves (Mytilus spp., Crassostrea gigas) also indicated different patterns of sediment toxicity in space and time. Sediments were most toxic to the amphipods at Redwood Creek (90% of the tests), and were toxic in at least half the tests conducted at five other sites. Sediment elutriates severely reduced normal bivalve larval development at the San Joaquin and Sacramento Rivers in all samples, but toxicity occurred in less than a third of the tests in the Central and South Bays. Toxicity could not be statistically related to seasonal freshwater flow or rainfall in the Bay, but seasonal variation in contaminant concentrations and toxicity was observed. Amphipod toxicity was inversely and significantly related to the mean effects range-median quotient, suggesting that cumulative concentrations of several contaminants were related to toxicity. Further analysis identified suites of specific contaminants at each site that were variably related to amphipod toxicity at each site. Chlordanes, cadmium, and silver were significantly related to amphipod survival in the North Bay. Seasonal patterns in low, and high molecular weight polycyclic aromatic hydrocarbons (PAHs) were related to toxicity at Alameda, and metals and PAHs were related to toxicity at Castro Cove. Larval bivalve toxicity was associated with metals in bulk sediments, but elutriate chemistry was not measured, and relationships with toxicity could not be examined. Hypotheses about effective concentrations of several individual contaminants and mixtures of contaminants were posed.     

Behavioral effects in mummichog larvae (Fundulus heteroclitus) following embryonic exposure to methylmercury

Embryos of the mummichog, Fundulus heteroclitus, were exposed to concentrations of methylmercury (meHg) below those that can cause morphological abnormalities. After hatching, larvae were kept in clean water and tested periodically for ability to capture prey (Artemia salina) or for their swimming performance and predator avoidance. Embryonic exposure to 10 μg/liter meHg resulted in reduced prey capture ability by early larvae, measured as total Artemia caught in 1 and 5 min. However, older larvae recovered from the behavioral deficits, perhaps owing to a compensation for early CNS insult. Fish from a chronically polluted environment (Piles Creek (PC), a tributary of the Arthur Kill), previously shown to have high tolerance to the teratogenic effects of higher concentrations of meHg, proved to be less susceptible to these behavioral effects than fish from a relatively uncontaminated site (EH). Also, the PC control larvae captured prey far more effectively than the EH larvae, although they made more miscues. When tested for swimming performance after embryonic exposure to 10 μg/liter, EH larvae had increased performance when compared to controls. This effect was also transitory. The improved swimming performance did not correspond to improved ability to avoid predation by grass shrimp (Palaemonetes pugio). The increased swimming performance may correspond to greater total activity, making them more likely to attract the predator's attention and resulting in increased capture. Thus, negative, though temporary, effects were observed in both prey capture and predator avoidance after embryonic exposure to meHg.     

Sublethal effects of the water-soluble fraction of ekofisk crude oil on the early larval stages of cod (Gadus morhua L.)

Low levels of dissolved oil hydrocarbons are demonstrated to produce sublethal effects on the early cod larval stages. These effects are discussed in relation to larval survival through the first critical stages.Continuous exposure of cod eggs and larvae to 0·05 and 0·25 ppm of the water-soluble fraction (WSF) of Ekofisk crude oil for 14 days caused significant reduction in growth and change in neutral buoyancy. The larvae exposed to 0·25 ppm showed malformation in the foremost part of the head and jaw, which reduced their ability to capture prey organisms at first feeding.     

Detecting a field gradient of PAH exposure in decapod crustacea using a novel urinary biomarker

Norwegian coastal waters are subject to PAH contamination from electrochemical industries such as aluminium smelters. Evidence of PAH exposure has been established in fish and bivalves. The present study tests the applicability of a novel crustacean PAH exposure biomarker to a PAH contamination gradient in the field (Karmsund Strait, SW Norway). Fluorescence analysis of urine samples collected from crabs at each site revealed 1-OH pyrene "equivalent" levels (indicative of pyrogenic PAH contamination) decreased with increasing distance from a point source of pyrogenic PAH (a large aluminium works). The assay was shown to be suitable for the detection of PAH exposure in wild crustacean populations, for discriminating between contaminated and clean sites and is also sufficiently sensitive to detect gradients of PAH contamination. The method provides a rapid, inexpensive and non-destructive measure of biologically available PAH in crustaceans.     

Apparent lack of CYP1A response to high PCB body burdens in fish from a chronically contaminated PCB site

Chronic exposure to organic contaminants such as polychlorinated biphenyls (PCBs) can lead to the development of resistance to these chemicals, a condition associated with reduced response of CYP1A1, a pollutant-inducible biomarker. We measured CYP1A activity (ethoxyresorufin o-deethylase, EROD) and PCB concentrations in feral fish from the Town Branch/Mud River system (Logan County, KY), a stream historically contaminated with PCBs and partially remediated. As a first step in evaluating the possible development of resistant populations in this system, we measured CYP1A expression and PCB body burdens in resident fish from sites we previously characterized as containing biologically significant levels of CYP1A inducing compounds. Mean PCB concentrations in edible flesh ranged from 75.2 to 16.7 microg/g in fish collected from Town Branch remediated sites and were relatively low (1.23 microg/g) in Town Branch reference site fish. However, hepatic CYP1A activity was similar among individuals of most species collected from reference and contaminated/remediated sites. The absence of elevated CYP1A levels in resident fish species despite the presence of significant PCB body burdens may indicate these fish have developed reduced sensitivity to CYP1A induction, a condition associated with acquired resistance to toxicants.     

Embryonic exposure to environmentally relevant concentrations of PCB126 affect prey capture ability of Fundulus heteroclitus larvae

Early life stages from a marine fish species, Fundulus heteroclitus, were exposed to sublethal doses of 3,3',4,4',5 pentachlorobiphenyl (PCB126) to evaluate its effects on ecologically relevant responses: growth and behavior. A few hours after fertilisation, eggs were treated topically with PCB126 (2.5-50 pg egg?1). Four days post-hatching (dph), morphological changes (body length and malformations), spontaneous locomotor activity (active swimming speed, rate of travel, % inactivity), prey capture ability (Artemia franciscana nauplii) and whole body EROD activity were evaluated in larvae. Untreated larvae collected at 0.5, 1, 2, 3, 4 dph were also examined. PCB126 did not increase the mortality or malformation rates. Body length and spontaneous locomotor activity were altered only in larvae treated with the highest dose. Treatment with PCB126 caused a dose-responsive reduction in prey capture ability (rate of decline in the number of Artemia) and induction of EROD activity. The lowest observed effective dose for both of these responses was 5.0 pg PCB126 egg?1 or 5.0 TCDD-toxic equivalents pg g?1 egg, using a TCDD-toxic equivalent factor of 0.005 and an egg mass of 5 mg. Prey capture efficiency (number of Artemia captured per feeding strike) was reduced at ≥ 10.0 pg egg?1. In untreated developing larvae, prey capture ability and efficiency increased as post-hatching development progressed and EROD activity remained low. The pattern of behavioral responses observed in PCB126-exposed Fundulus larvae differed from that observed in less-developed larvae indicating that other mechanisms than retarded development were involved. Behavioral dysfunction was a more sensitive response to PCB126 than morphological alterations and it occurred at environmentally relevant concentrations.     

A description of chloride cell and kidney tubule alterations in the flatfish Solea senegalensis exposed to moderately contaminated sediments from the Sado estuary (Portugal)

The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level (TEL) and the Probable Effects Level (PEL). The Sediment Quality Guideline Quotient indices (SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic balance, contributing for the high mortality levels observed. The results suggest that sediment-bound organic contaminants such as PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls) may be very toxic to the analyzed organs, especially the kidney, even when present in low-risk concentrations.     

A description of chloride cell and kidney tubule alterations in the flatfish Solea senegalensis exposed to moderately contaminated sediments from the Sado estuary (Portugal)

The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level (TEL) and the Probable Effects Level (PEL). The Sediment Quality Guideline Quotient indices (SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic balance, contributing for the high mortality levels observed. The results suggest that sediment-bound organic contaminants such as PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls) may be very toxic to the analyzed organs, especially the kidney, even when present in low-risk concentrations.     

Elucidating cellular and behavioural effects of contaminant impact (polycyclic aromatic hydrocarbons,PAHs) in both laboratory-exposed and field-collected shore crabs,Carcinus maenas (Crustacea: Decapoda)

Monitoring effects of contaminants at lower levels of biological organisation (e.g. biochemical and cellular) allows for mechanistic evaluation of effects of contaminant exposure through laboratory exposures. However, higher level organism effects (e.g. physiological and behavioural) are deemed more ecologically-relevant. In the present study, cellular (cell viability and immune function), physiological (cardiac activity) and behavioural (foraging behaviour) responses were evaluated in field-collected shore crabs Carcinus maenas from three estuaries [a ‘relatively’ (polycyclic aromatic hydrocarbon) PAH-contaminated site (Plym Estuary) and two ‘comparatively clean’ field sites (Avon and Yealm Estuaries)] and compared with responses of crabs exposed in the laboratory to a model organic contaminant (PAH) pyrene (200 μg l⁻¹ for 28 days). The hypothesis that behavioural indicators may be more sensitive than other more traditional methods was tested. No significant impacts were observed at the cellular or physiological level in Plym-collected crabs (the ‘relatively’ contaminated site), but foraging behaviour was significantly altered (increased prey handling time) compared to individuals collected from the ‘relatively’ uncontaminated sites (Avon and Yealm). When given a cockle as a prey item, both Plym-collected and laboratory-exposed crabs took longer to handle and break into cockle shells. Therefore, ecologically-relevant behavioural observations may serve as valuableindicators of environmental quality.     

Lack of development of pollutant-resistance or genetic differentiation in darter gobies (Gobionellus boleosoma) inhabiting a produced-water discharge site

Physiological acclimation, genetic adaptation and genetic differentiation were examined in darter gobies (Gobionellus boleosoma) inhabiting a coastal marsh with a long history of PAH contamination. No acclimation was detected; a 2-week pre-exposure at the polluted site resulted in a decreased rather than an increased resistance in a subsequent laboratory exposure to polluted sediment. Similarly, fish collected from sites with elevated sediment PAH levels did not exhibit an increased resistance in bioassays with polluted sediment, confirming the lack of acclimation and indicating a lack of adaptation to the pollutants. No differences were detected in frequencies of allozyme genotypes when comparing gobies from the polluted area to those from a nearby control site, and overall levels of heterozygosity were similar in the two populations. While lack of UV-induced toxicity in the laboratory exposures could have played a role, at least four other factors may explain the apparent lack of adaptive responses and genetic differences. First, bioavailability of the contaminants to the darter goby could have been low, though other evidence contradicts this. Second, the contaminated marsh contains a large number of different chemicals and acclimation, adaptation and genetic differentiation are expected to be less likely when more contaminants are involved. Third, the hydrocarbon distribution at the contaminated marsh is very patchy, such that fish may avoid exposure to the highly-contaminated sediment. Fourth, gene flow may be sufficiently high in this mobile species to prevent local adaptation.     

Metal concentrations and metallothionein-like protein levels in deep-sea fishes captured near hydrothermal vents in the Mid-Atlantic Ridge off Azores

The knowledge of metal contamination in deep-sea fishes living in the surroundings of hydrothermal vents is very scarce, along with the detoxification mechanisms that allow them to live near one of the most metal contaminated marine environments. Six deep-sea fish species, although not vent endemic were collected near three Mid-Atlantic Ridge (MAR) hydrothermal vents (Menez Gwen, Lucky Strike and Rainbow) and the gills, muscle and liver were selected for this study due to their importance in metal metabolism and storage. The concentrations of seven metals (Ag, Cd, Cr, Cu, Fe, Mn, and Ni) and a metal-related biomarker (metallothionein-like proteins–MTL) were assessed. Major differences in metal accumulation among fish species are related to their feeding habits and vent site of their capture. The liver and gills are in general the most important tissues for metal accumulation compared to the muscle, but tissue partitioning is very dependent on the fish species considered. Compared to other deep-sea fishes, fish capture in the vicinity of hydrothermal vents accumulates higher amounts of metals in general. However, MTL levels are not considerably different from what is found in commercial coastal fishes, and is poorly correlated with metal concentrations in the tissues. Therefore, MTL may not constitute one major detoxification system for deep-sea species living in the vicinity of three important MAR vent sites.     

Vertical distribution and growth performance of Baltic cod larvae – Field evidence for starvation-induced recruitment regulation during the larval stage?

Besides variable egg survival, previous studies suggested that the larval stage may be the most critical phase in determining Baltic cod recruitment variability, and that larvae need to conduct an ontogenetic vertical migration from hatching depths (>50 m) to upper layers with increased food availability in order to initiate first feeding, improve their nutritional condition and growth, and avoid starvation. Recently, detailed information on the stage-resolved vertical distribution of main Baltic copepod species, including the preferred larval Baltic cod prey species Pseudocalanus acuspes, has become available. Therefore, the vertical distribution of Baltic cod larvae in August 2007 and their depth-dependent nutritional condition and growth were investigated. RNA–DNA based methods were used to estimate growth, including a novel approach to estimate growth performance by relating observed specific growth rates (SGR) of field caught larvae to temperature-dependent reference growth rates (G_ref) for fast-growing laboratory reared fish from the literature. This standardization to G_ref was found to have a great potential to improve investigations on the growth and ecology of larval fish. The need for early larvae to migrate to shallower layers was corroborated, while larger size classes were found at increasingly greater depths. This may reflect a continuation of the ontogenetic vertical migration in order to follow increasingly larger prey items at greater depths and to save energy in cooler waters below the thermocline. Larval growth generally declined with increasing depth, but the decline in growth became less pronounced in larger size classes. This indicates that larger larvae were better in coping with the ambient environment and the available prey field at greater depths. Generally, Baltic cod larvae grew poorly compared to larvae from other studies, which is discussed in relation to differences in predation and a possible food–temperature trade-off for larvae in the highly stratified Baltic Sea. Comparison with earlier results showed a higher frequency of starving larvae and lower frequencies of larger larvae after the first-feeding stage in 1994 and 1995. As this was a period of low Baltic cod recruitment despite favourable conditions for egg survival, it is concluded that larval starvation mortality has a high potential to contribute to recruitment variability in Baltic cod.     

The tropical brown alga Lobophora variegata as a bioindicator of mining contamination in the New Caledonia lagoon: a field transplantation study

Previous field and laboratory studies have identified the alga Lobophora variegata as a good candidate for biomonitoring metal contamination in the New Caledonia lagoon which is subjected to intensive and extensive metal inputs from land-based mining activities. The aim of this work was to further assess the bioindicative potential of this species by investigating, in the field, its bioaccumulation capacity for local key contaminants, i.e. Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn. Algae from clean and contaminated sites were cross-transplanted for a period of three months in order to determine the in situ uptake and depuration kinetics of the nine elements. Results indicate that algae transplanted to the contaminated site displayed a significant linear increase in concentration with time for Ag, As, Cd, Co, Cr, Cu, Mn and Ni. In contrast, algae transplanted to the clean site did not show major depuration of these elements, except for Co. Overall, L. variegata showed a rapid temporal response in metal uptake, especially for the elements intensively released into the coastal environment of New Caledonia (viz., Co, Cr, Mn and Ni). This species appears therefore as an excellent bioindicator species of metal contamination in this area. Our results also provide background information necessary for using L. variegata under in situ experimental conditions so as to provide better quantitative information on ambient metal contamination levels. The wide distribution of L. variegata in tropical areas further enhances its potential as a bioindicator species of metal contamination in other tropical coastal environments.     

Does historical exposure to hydrocarbon contamination alter the response of benthic communities to diesel contamination?

A microcosm experiment was used to compare the influence of diesel contamination on two benthic salt-marsh communities, one chronically exposed to petroleum hydrocarbons for decades (Louisiana [LA]) and the other relatively uncontaminated (Mississippi [MS]). Initial meiofaunal community composition of the two sites was similar. Higher organic content of MS sediments should have reduced bioavailability, and thus the toxicity of hydrocarbons relative to the LA site. Nevertheless, although responses to diesel contamination at the two sites were generally qualitatively similar, a species-specific and several community-response variables were influenced to a much greater degree in the MS community. In particular, the abundance of total nauplii, ostracods, and copepods were negatively impacted to a greater extent in MS than in LA, as was grazing by ostracods on benthic microalgae. Nematode:copepod ratios in contaminated sediments were much higher in MS than in LA sediments. Pseudostenhelia wellsi (a benthic copepod) nauplii suffered greater adverse effects of diesel in MS than in LA. We conclude that the MS community was more sensitive to diesel contamination than was the LA community. The differential sensitivity is presumably a manifestation of different tolerances to hydrocarbon contaminants, mediated by a higher proportion of more tolerant species and/or increased tolerance among individual species in LA. Although the MS site was more sensitive to diesel contamination, qualitative response of the LA and MS communities were similar, and comparable to previous studies of diesel contamination. The spatial and temporal consistency of diesel impacts on salt-marsh communities suggests that hydrocarbon contamination results in predictable community responses. Specifically, crustacean (e.g. copepods, ostracods, and nauplii) benthos are most sensitive to hydrocarbons. Reductions in abundance and grazing activity of crustaceans leads to enhanced algal biomass, reduced copepod diversity, and alters competitive interactions among meiofauna.     

The sea-surface microlayer of puget sound: Part I. Toxic effects on fish eggs and larvae

The sea surface is an important habitat for the developmental stages (eggs and larvae) of many fish and invertebrates; it is also a concentration point for anthropogenic contaminants entering the sea. Studies were conducted to determine the extent to which the sea surface of Puget Sound was toxic to the early life history stages of fish. Three urban bays with suspected contamination, a rural reference bay, and a Central Sound site were compared. Surface-dwelling eggs and organisms (zooneuston) were collected with a surface-skimming neuston net and their densities enumerated. Sand sole (Psettichthys melanostictus) embryos were exposed in the field and laboratory to the sea-surface microlayer. To develop a useful year-round approach to monitoring sea-surface toxicity, larval development of anchovies, kelp bass, and sea urchins was also evaluated as an indication of sea-surface microlayer toxicity.During the spawning season (February and March), urban boys in Puget Sound had lower concentrations of sand sole eggs and neustonic organisms on the sea surface than did the rural bayor Central Sound reference sites. Compared to the reference sites, laboratory exposure to surface microlayer samples collected from urban bay sites generally resulted in more chromsomal aberrations in developing sole embryos, reduced hatching success of sole larvae, and reduced growth in trout cell cultures. In situ hatching success of sole eggs was reduced by half or more in urban bays compared to reference sites.Toxicity was associated with visible surface slicks and, in urban bays, increased with increasing surface pressure (dynes cm⁻¹). Results to be reported separately (Part II) indicate that toxicity is strongly correlated with the presence of high concentrations of polycyclic aromatic hydrocarbons and metals in the sea-surface microlayer. The toxicity of SMIC samples was similar when evaluated by sole, anchovy, kelp bass, or sea urchin tests. A sea-surface monitoring program could use sea urchin embryos to evaluate site-specific sea-surface toxicity throughout the year.     

Endocrine disruption: thyroid dysfunction in mummichogs (Fundulus heteroclitus) from a polluted habitat.

Mummichogs (Fundulus heteroclitus) from Piles Creeks (PC), New Jersey (a polluted site), are sluggish and show poorer prey capture and predator avoidance than reference fish from Tuckerton (TK). The behavioral dysfunction of the PC fish may be associated with thyroid impairment due to endocrine disruption. In this study, we compared thyroid histology and thyroid hormones in the two populations and determined experimentally whether the polluted environment could alter thyroid hormone levels. PC fish had larger thyroid follicles, greater follicle cell heights, and contained higher plasma thyroxine (T4) levels than TK fish. However, there were no significant differences in either plasma or tissue triiodothyronine (T3). TK fish held in simulated PC environments had higher plasma T4 and lower plasma T3 than field-sampled fish. PC fish held in clean water had lower plasma T4 and T3 than field-sampled fish. In either case, there was no significant difference in tissue T3 content. The contaminants in PC alter thyroid structure and function, which may relate to the behavioral differences between fish from the polluted and reference sites.     

Genotoxicity in two bivalve species from a coastal lagoon in the south of Portugal

DNA damage was evaluated by comet assay in the haemolymph of two bivalve species Ruditapes decussatus and Mytilus galloprovincialis from the Ria Formosa lagoon (south Coast of Portugal). Clams and mussels were sampled from sites close to each other to determine interspecific responses to similar environmental conditions, considering also seasonal and gender differences. Coupled with genotoxic effect, another damage biomarker (lipid peroxidation) was analysed to verify if the conditions that instigate DNA damage can be related with injury to cell membranes. For both species, DNA damage was low, reflecting the low levels of genotoxic contaminants in the lagoon, and no interspecific differences were found. However, seasonal differences were established for both bivalve species, reflecting higher environmental stress in summer. Regarding gender susceptibility, only clams showed differences in percentage of Tail DNA, with females more sensitive to DNA damage than males. Additionally, results for clams point out that factors responsible for LPO may not be the same as those causing genotoxicity. This study demonstrated that DNA damage is a sensitive biomarker to discriminate spatial, temporal and gender differences, being an appropriate biomarker for genotoxicity evaluation even in places of low contamination, such as the Ria Formosa lagoon.     

Does the zooplankton prey availability limit the larval habitats of pike in the Baltic Sea?

The objectives of this study were to (1) investigate whether the availability of suitable zooplankton prey limits the distribution of the coastal larval areas of pike (Esox lucius) in two archipelago areas of the northern Baltic Sea and (2) compare the availability of zooplankton prey in spring between different types of coastal littoral habitat. According to the results, reed belt habitats formed by Phragmites australis constitute hot spots for zooplankton prey in the coastal ecosystem. During the spring, reed-covered shores of the inner archipelago maintained more than 10 times higher densities of copepods and cladocerans, the preferred prey for larval pike, compared to the other studied shores. Temperature conditions were also most favourable in the reed belt habitat. Thus, the reed belts of the inner and middle archipelago were shown to form the best habitat for larval pike in the coastal area of the northern Baltic Sea, and this was also the only habitat where pike larvae were found. Our results suggest that the poor survival and recruitment of pike in the outer archipelago, however, cannot exclusively be explained by sub-optimal feeding conditions of the larvae. There are also other important factors, presumably connected to the exposure to the open sea, that affect the distribution of the pike larvae. Our results, however, highlight the importance of sheltered coastal reed belt shores as reproduction habitat for spring-spawning fish in the northern Baltic Sea. Further, this study disproves the assumption that the seaweed bladder wrack (Fucus vesiculosus) forms a reproduction habitat for pike in the coastal area.     

Alteration of the biochemical properties of female gonads and vitellins in the clam Mya arenaria at contaminated sites in the Saguenay Fjord

Vitellins (Vn) are the major egg yolk proteins that constitute an important energy reserve for mollusc embryos. The purpose of the present study was to examine whether the relative levels of sugars, lipids, phosphates, and labile IIb metals and calcium normally associated with Vn would differ in clam populations living at contaminated sites. Softshell clams (Mya arenaria) were collected at three sites in the area of the Saguenay Fjord: a marina, a municipal sewer outfall zone, and a reference site. The condition factor (weight:length ratio), metallothionein-like proteins, cytochrome P450 1A1 activity and DNA damage were all determined in the clam's digestive gland. Levels of total sugars, lipids, alkali-labile phosphates, proteins, and labile zinc and calcium were determined in female gonad homogenates and in purified Vn. The results show that clam gonads at the contaminated site by a marina displayed a lower index of gonad activity than the reference site. In addition, the condition factor was significantly lower at the marina site as compared to the reference site, with a concomitant increase in DNA damage and metallothionein (MT) induction. In fact, the condition factor was significantly correlated with DNA damage (R = -0.413, P = 0.045) and MT levels (R = -0.622, P = 0.03). Homogenates of female gonads were found to contain higher levels of labile IIb metals and calcium, with lower lipid content at the marina site compared to the reference site, and much higher levels of alkali-labile phosphates (ALP) and calcium at the municipal outfall site. Vn from the marina site were significantly higher in labile IIb metals but lipid content appeared to be somewhat lower than at the reference site. Vn from the municipal site were found to be highly phosphorylated, with higher levels of lipids and calcium. These results suggest that the chemical composition of the gonads and Vn are altered in contaminated sites.