María Luisa González de Canales

Lindane toxicity on early life stages of gilthead seabream (Sparus aurata) with a note on its histopathological manifestations.

Eggs/embryos and larvae were exposed to nominal concentrations ranging from 0.1 to 10mg/L lindane. High percentage of mortality was observed in larvae exposed to 1mg/L (76.38%) and in embryos exposed to 10mg/L (81.98%) of lindane at 24h exposure. The acute toxicity expressed as LC(50) 48-h was 0.122mg/L for embryos and 0.318mg/L for larvae. Larvae alterations included weak swimming, incapacity to respond to external stimuli, uncoordinated movements, trembling, myoskeletal defects, opaque skin and exophthalmia. Mucous epithelium of the digestive tissue showed a severe alteration with hypertrophy and desquamation of mucous cells. A high cellular disorganization in the renal and hepatic tissue is observed. Results obtained showed the sensitivity of Sparus aurata early life stages to lindane and the presence of sublethal effects like histopathological alterations; therefore, the relevance of pesticides substances control in the aquatic environment.

Chronic bioassay in benthic fish for the assessment of the quality of sediments in different areas of the coast of Spain impacted by acute and chronic oil spills

More and more, the coastal regions of the world suffer from the contamination of petroleum hydrocarbon [principally polycyclic aromatic hydrocarbons (PAHs)]. This contamination can be acute, as it happened in the Coast of Galicia (NW, Spain) by the oil spill from a tanker, or chronic by the existence of high maritime traffic and a lot of industries as it is the case of the Bay of Algeciras (BA) (SW, Spain). It is of a great concern due to the toxicity, especially in sediments and ecosystem associated to it. The objective of this study is to assess, through chronic bioassay, sediment toxicity in samples collected in different littoral areas of Spain and to compare the damage caused in benthic fish, Solea senegalensis, according to that which suffers acute spill (Coast of Galicia) or chronic spill (the BA) by means of histopathology methods and enzymatic activities studies. Organisms were exposed to different sediments from Galician Coast and the BA during 42 days and every sample was analyzed by triplicate in glass aquaria. At the end of the bioassay, histopathological diseases were analyzed in the gills, target organ. Likewise, stress parameters as ethoxyresorufin‐O‐deethylase (EROD) and the glutathione S‐transferases (GSTs) activities were determined in the liver. Results showed a significant positive correlation between the biomarkers of exposure (EROD and GST), biomarkers of effect (histopathology), and PAHs concentrations in the sediments.

Evaluation of acute copper toxicity during early life stages of gilthead seabream, Sparus aurata.

In this study, the effects of exposure to copper (mortality and morphological alterations) on the early life stages of the gilthead seabream, Sparus aurata, were examined. Eggs/embryos and larvae were exposed to nominal concentrations of copper ranging from 0.0001 to 10 mg/L Cu (II) in the tests with eggs/embryos and 0.025 to 0.5 mg/L Cu (II) in the test with larvae. Duration of the assays was 48 hours for embryos and 96 hours for larvae. A high percentage of mortality was observed in embryos exposed to 0.1 mg/L (97.2%) and in larvae exposed to 0.5 mg/L (100%). The embryos proved the most sensitive to copper for the same duration of exposure. The acute toxicity expressed as LC50 48 hours was 0.054 (0.048–0.058) mg/L for embryos and 0.261 (0.182– 0.375) mg/L for larvae. Morphological alterations or abnormalities in embryos included irregular shapes of chorion, opacity and vitellus retraction/degeneration. In larvae we observed poor capacity to swim, trembling, myoskeletal defects, opacity and exophthalmia. Histopathological alterations are observed in S. aurata larvae. Mucous cells of the digestive tissue present a severe alteration with an increment of exudates. A great cellular disorganization in the renal tissue is observed. Results from this work indicate the high sensitivity of early life stages of Sparus aurata to copper (II) and the persistence of sublethal effects.

Toxicity of lindane (γ-hexachloroxiclohexane) in Sparus aurata, Crassostrea angulata and Scrobicularia plana

The purpose of the present study was to research the sublethal and/or lethal effects produced by the exposure of fish and shellfish to the γ isomer of lindane, γ-hexachlorocyclohexane (γ-HCH). The teleostean fish Sparus aurata and the shellfish Crassostrea angulata and Scrobicularia plana, were exposed to 16 μ g/L of lindane for 15 days. Samples of different fish (liver, kidney and gills) and shellfish (gills, gut, digestive gland and mantle) tissues were extracted and processed for histopathological observations. Although mortality was not detected during the bioassay, sublethal effects (histopathological alterations) were observed. Vacuolization in the liver cells and lamellar fusion in gills from exposed fish were observed. Disorganization of normal gill structure, epithelial desquamation with the disappearance of apical ciliature in intestine, and inflammatory response in mantle from exposed shellfish were also observed. Thus, it can be concluded that the lindane concentration employed in the present research did not produce lethal effects in the exposed organisms but it caused sublethal effects. Lindane has time-dependent multiple toxic effects in S. aurata, C. angulata and S. plana, which were more severe at the end of the experimental time. The toxicological implications arising from these results are subjects for further multiconcentration tests dealing with lethal responses (mortality) or with sublethal responses (cellular/molecular biomarkers) of the aforementioned species.

Reproductive cycle of Spisula solida (L.) (Mollusca: Bivalvia) on the southwest coast of Spain

The reproductive cycle of Spisula solida (L., 1758) was investigated for the first time in the southwest of Spain, using specimens collected from Punta Umbría (Huelva), between April 2001 and May 2002. A total of 2805 individuals of shell lengths ranging from 9.1 to 38.4 mm were analysed. The gonad development was determined by means of histological methods and variations of dry weight. Five gametogenic stages were identified (I-Immature, II-Maturing, III-Ripe, IV-Spawning, V-Post-spawning). The sex-ratio obtained was 5:4 (χ 2 = 6.12, df = 1, p > 0.01), males being more abundant than females. Two hermaphrodite individuals were recorded. Development of the gonad began in November and spawning occurred between December and June, with maximum peaks in April (82% males) and May (87% females). The period of sexual rest took place from July to October. Gametogenesis in this species is a response to low seawater temperatures, and spawning occurs with low temperatures that increase progressively.