[Show abstract][Hide abstract] ABSTRACT: The present study deals with the effect of trace metals on the endangered limpet Cymbula nigra. The Bay of Algeciras (Strait of Gibraltar) was used as the study site. Important industrial activity takes place in the area, including frequent oil spills. However, it is home to important populations of C. nigra. The objective of this work was to determine if these animals were being affected at a subcellular level by the pollutants present in their environment and to analyze the trace metal concentrations in the animal’s soft tissues. To determine the effects of water quality on the antioxidant activity and concentrations through field experimentation, a total of six sites were selected in Algeciras Bay, three located in the inner areas (environmentally degraded sites with higher levels of pollutants) and three in the outermost areas of the Bay. Stress associated to reactive oxygen species formation was assessed on digestive glands and gills as the enzymatic antioxidant activity of catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) and as the concentrations of lipid-soluble (α-tocopherol and β-carotene) and the water-soluble antioxidants (reduced and oxidized glutathione (GSH and GSSG)). Gills and digestive glands of those animals located in the inner areas of Algeciras Bay showed higher CAT activity values than those located in the outer areas. As a general pattern, we observed higher antioxidant activities and concentrations in digestive glands that in gills, suggesting the possibility that pollutants are mainly being incorporated by limpets through the food. As a general rule, larger animals showed greater concentrations of these compounds. Iron, zinc, and manganese, in this order, were present in the tissues at the highest concentrations. Chromium and manganese were found in significantly higher concentrations in those animals collected from the inner areas of the Bay. Through the present study, we provide the first data regarding the antioxidant defense levels and metal accumulation capacity of this species, and we reinforce the idea that this endangered species may be, in fact, relatively tolerant to degraded environments.
Water Air and Soil Pollution 02/2013; 224:1458. · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study establishes the reproductive cycle, batch fecundity and oocyte diameter of a diadromic population of the puyen, Galaxias maculatus, in the Río Ovando, Tierra del Fuego, (54°S), at the southernmost limit of its distribution. Given the short ‘favourable season’ in relation to other populations of the species (in terms of temperature, photoperiod and food availability), the study also explores the trade-offs between feeding and oocyte production and between phases of growth and reproduction. The reproductive cycle was analyzed by the monthly evolution of the proportion of gonadal maturity stages (determined from microscopic examination of the gonads). Oocytes were measured using a micrometric ocular scale and classified by diameter and morphological characteristics; absolute fecundity was established as the total number of hydrated oocytes per ovary. The studied population exhibits a repetitive spawning strategy, given the coexistence of post-ovullatory follicles and hydrated oocytes in histological sections and the presence in ripe ovaries of an intermediate cohort of yolked oocytes ready for hydration. Individual fecundity is lower (1422 ± 422 oocytes/ovary) than in other puyen populations, but the egg production increases through individual repetitive spawnings during the protracted spawning period (from October to February). Females attain larger sizes than those of other South American populations (the largest female reaching 115 mm total length), maximizing its potential fecundity. The present paper contributes to the knowledge of the variability of reproductive traits of G. maculatus in relation to diadromic populations, given that the bulk of information in South America refers to landlocked populations.
[Show abstract][Hide abstract] ABSTRACT: The aim of this work was to study comparatively the oxidative metabolism in gills and liver of a silverside, Odontesthes nigricans, in their natural environment, the Beagle Channel. Oxidative damage to lipids was evaluated by assessing TBARS and lipid radical content, in gills and liver. Gills showed a significantly higher degree of damage than liver. The content of alpha-tocopherol, beta-carotene and catalase activity showed significantly higher values in the liver than in the gills. The ascorbyl radical (A(*)) content showed no significant differences between gills and liver. The ascorbate (AH(-)) content was 12+/-2 and 159+/-28 nmol/mg FW in gills and liver, respectively. Oxidative metabolism at the hydrophilic level was assessed as the ratio A(*)/AH(-). The ratio A(*)/AH(-) was significantly different between organs, (6+/-2)10(-5) and (5+/-2)10(-6), for the gills and the liver, respectively. Both, lipid radical content/alpha-tocopherol content and lipid radical content/beta-carotene content ratios were significantly higher in gills as compared to the values recorded for the liver, suggesting an increased situation of oxidative stress condition in the lipid phase of the gills. Taken as a whole, the O. nigricans liver exhibited a better control of oxidative damage than the gills, allowing minimization of intracellular damage when exposed to environmental stressing conditions.
Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology 09/2009; 154(4):406-11. · 1.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principal-components analysis (PCA) of the ED of the different organs/tissues indicated that PC(1) and PC(2) accounted for 87% of the variability. Separation along PC(1) corresponded to differences in muscle and liver energy densities whereas separation along PC(2) corresponded to differences in the ED of the gonads. Differences between species were significant except for P. sima. Inclusion of the gonadosomatic index (GSI) as an explanatory variable enabled us to establish the existence of energy transfer from muscle and liver to the gonads in ripe P. tessellata females. Total ED values varied between 4.21 and 6.26 kJ g(-1), the pelagic Odontesthes sp. being the species with the highest ED. A significant relationship between ED and muscle dry weight (DW(M)) was found for all the species except P. tessellata. These data are the first direct estimates of ED of fishes from the Beagle Channel.
Fish Physiology and Biochemistry 04/2009; 35(1):181-8. · 1.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A population of Galaxias maculatus, a native species in southern South America, living under cold-temperate conditions (0°C water temperature with an ice layer
covering the stream during the coldest days) and 7h of light in winter undergoes high energetic demands in the population
studied. We analyzed the energy density of gonads, liver, fat and muscle, through calorimetry for the first time in this species.
Energy density of fat and liver were extremely high (34.77–56.52 and 29.54–40.77kJ/g respectively). While perivisceral fat
reserves were likely used for overwintering, liver and muscle reserves were used for reproduction. High energy densities were
also found in gonads (27.76kJ/g in ovaries and 25.84kJ/g in testes). High investment in gonads of males suggests the presence
of sperm competition. The temporal variation of the energy content of gonads, liver, fat and muscle indicates that the allocation
of energy occurs by the internal transference of energy between organs and tissues.