The freshwater artisanal fishery of Patos Lagoon.

In this study data relative to the fishery in the freshwater area of the Patos Lagoon are analysed, and the dynamics, fishing gears used and catches evaluated. The results reveal the existence of two fishery strategies: forbidden mesh size gillnets (FMG; <35 mm; square measure) and allowed mesh size gillnets (AMG; ≥35 mm; square measure). In total, 31 species were caught (AMG = 27 and FMG = 24), but selectivity due to mesh size was significant (P < 0·001). The FMG may be very harmful since it captures individuals of most species below size at first maturity, including the target species, the armoured catfish Loricariichthys anus (61% of the total catch). In addition, this gear is used throughout the year, including the closed season (CS; November to January), when the target species is reproducing. Target species for the AMG are larger in size, comprising mainly the mullet Mugil liza, the marine catfish Genidens barbus and the whitemouth croaker Micropogonias furnieri. AMS gillnets were not used during the CS. The use of FMG reveals the need for effective fishery law enforcement and the need for additional studies to assess the status of populations of the exploited species.

Modeling fish biological responses to contaminants and natural variability in estuaries.

Understanding the factors that influence biological responses to contaminants has long been a major goal in marine environmental research. Seven estuarine sites along the Portuguese coast were sampled over a year, and different biological responses of Pomatoschistus microps and Atherina presbyter were determined: superoxide dismutase, catalase, ethoxyresorufin O-deethylase, glutathione S-transferase, metallothioneins, lipid peroxidation, RNA:DNA ratio and condition factor K. Generalized linear models (GLM) were developed for each biological variable per species in relation to sediment chemical characterization (metals and polycyclic aromatic hydrocarbons concentration) and environmental conditions (month, site, water temperature, salinity, depth and mud percentage in the sediment). GLM varied in explanatory power and in the set of predictor variables included in the models. Environmental factors were frequently selected as predictor variables. Individual metals concentration and sediment quality guidelines (integrating all metals) were the major contaminants explaining biological variability. Accordingly, models for metallothioneins and lipid peroxidation had highest explanatory power. Species-specific responses and dataset size were the basis of observed differences between GLM for the two species.

Influence of temperature in thermal and oxidative stress responses in estuarine fish.

The influence of increasing temperatures in thermal and oxidative stress responses were studied in the muscle of several estuarine fish species (Diplodus vulgaris, Diplodus sargus, Dicentrarchus labrax, Gobius niger and Liza ramada). Selected fish were collected in July at the Tagus estuary (24±0.9°C; salinity of 30±4‰; pH=8). Fish were subjected to a temperature increase of 1°C.h(-1) until they reached their Critical Thermal Maximum (CTMax), starting at 24°C (control temperature). Muscle samples were collected during the trial and results showed that oxidative stress biomarkers are highly sensitive to temperature. Results from stress oxidative enzymes show alterations with increasing temperature in all tested species. Catalase (CAT; EC 1.11.1.6) activity significantly increased in L. ramada, D. labrax and decreased in D. vulgaris. Glutathione S-transferase (GST; EC 2.5.1.18) activity increased in L. ramada, D. sargus, D. vulgaris, and D. labrax. In G. niger it showed a cycle of increase-decrease. Lipid peroxidation (LPO) increased in L. ramada, D. sargus and D. labrax. With respect to correlation analysis (Pearson; Spearman r), the results showed that oxidation products and antioxidant defenses were correlated in L. ramada (LPO-CAT and LPO-GST, D. sargus (LPO-CAT), and D. labrax (LPO-CAT). Oxidative biomarkers were correlated with thermal stress biomarker (Hsp70) in L. ramada (CAT-Hsp70), D. vulgaris (LPO-Hsp70), D. labrax (GST-Hsp70) and G. niger (LPO-Hsp70). In conclusion, oxidative stress does occur with increasing temperatures and there seems to be a relation between thermal stress response and oxidative stress response. The results suggest that oxidative stress biomarkers should be applied with caution, particularly in field multi-species/multi-environment studies.

Thermal tolerance of the crab Pachygrapsus marmoratus: intraspecific differences at a physiological (CTMax) and molecular level (Hsp70).

Temperature is one of the most important variables influencing organisms, especially in the intertidal zone. This work aimed to test physiological and molecular intraspecific differences in thermal tolerance of the crab Pachygrapsus marmoratus (Fabricius, 1787). The comparisons made focused on sex, size, and habitat (estuary and coast) differences. The physiological parameter was upper thermal limit, tested via the critical thermal maximum (CTMax) and the molecular parameter was total heat shock protein 70 (Hsp70 and Hsp70 plus Hsc70) production, quantified via an enzyme-linked imunosorbent assay. Results showed that CTMax values and Hsp70 production are higher in females probably due to different microhabitat use and potentially due to different hormonal regulation in males and females. Among females, non-reproducing ones showed a higher CTMax value, but no differences were found in Hsp70, even though reproducing females showed higher variability in Hsp70 amounts. As reproduction takes up a lot of energy, its allocation for other activities, including stress responses, is lower. Juveniles also showed higher CTMax and Hsp70 expression because they occur in greater shore heights and ageing leads to alterations in protein synthesis. Comparing estuarine and coastal crabs, no differences were found in CTMax but coastal crabs produce more Hsp70 than estuarine crabs because they occur in drier and hotter areas than estuarine ones, which occur in moister environments. This work shows the importance of addressing intraspecific differences in the stress response at different organizational levels. This study shows that these differences are key factors in stress research, climate research, and environmental monitoring.

Diet and niche overlap of southern populations of brill Scophthalmus rhombus and turbot Scophthalmus maximus.

The diets of adult brill Scophthalmus rhombus and turbot Scophthalmus maximus from the Portuguese coast relied mostly on fishes. There was a higher diversity of food items compared to their northern counterparts, and several of the identified prey are the first records of these species, including a brown alga, echinoderms, nematodes, oligochaetes, gastropods, bivalves and various fish species. The diet of the two species was significantly different and niche overlap was low.

Short-term variability of multiple biomarker response in fish from estuaries: Influence of environmental dynamics.

Short-term variability in biomarker responses and the effects of temperature and salinity variation were explored in three fish species (Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps) occurring in the Tejo estuary. Short-term variability in biomarkers was observed in all species although no pattern was discerned over time (days to weeks). Antioxidant enzymes activity (superoxide dismutase (SOD) and catalase (CAT)) showed low temporal variability, indicating some constancy or baseline level in antioxidant responses. Only CAT activity in S. senegalensis was correlated with temperature, suggesting that exposure to contaminants triggered antioxidant acclimation. Higher short-term variability was observed in xenobiotic biotransformation enzymes activity (phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST)). Yet a significant correlation between EROD and GST in D. labrax and S. senegalensis suggests a concomitant response to contaminants. Moreover the lack of correlation between xenobiotic biotransformation enzymes and abiotic variables on concordant time scales, suggest a high specificity of these biomarkers to chemical exposure, rather than high variability due to environmental dynamics.

Multi-biomarker responses to estuarine habitat contamination in three fish species: Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps.

Several biomarker responses were determined in three fish species, Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps, from two estuaries of the Portuguese coast, Ria de Aveiro and Tejo. Both estuaries have significant anthropogenic influences from multiple sources (industrial, agricultural and shipping activities), which was evident from sediment chemical characterization concerning metal (copper, zinc, nickel, lead and chromium) and polycyclic aromatic hydrocarbon (PAH) concentrations. Spatial variability in fish responses was observed across species for most biomarkers of exposure [the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), and metallothionein concentrations (MT)] and effect biomarkers [lipid peroxidation (LPO), RNA to DNA ratio (R:D), protein and lipid content]. In general, the interspecific differences in biomarker responses were greater than the spatial differences, due to differences in the behavior and habitat use of the species. Nevertheless, similarities were also observed considering both chemical load and biomarker responses. In highly polluted sites fish showed in general a significant antioxidant enzyme induction, associated with decreased R:D values, while fish from the least impacted site had little enzyme induction and better condition indices (high R:D and low LPO values). EROD activity was also higher for all species in the Tejo than Ria de Aveiro estuary, despite the generally higher total PAH measured in Ria de Aveiro, most likely due to a higher proportion of 4 and 6-ring PAHs, considered more toxic than low molecular weight PAHs, in the Tejo. In conclusion, this multi-biomarker approach considering multiple species provided improved understanding of the diverse responses and effects of exposure to contaminants and the effective risk it poses for different fish species.

Host-parasite relationships in flatfish (Pleuronectiformes)--the relative importance of host biology, ecology and phylogeny.

The extent to which host biology, ecology and phylogeny determine the diversity of macroparasite assemblages has been investigated in recent years in several taxa, including fish. However, consensus has not been reached probably as a result of data being collected from different sources, different temporal scales or host and parasite biogeography and phylogeny having greater influence than expected. The present study evaluates the relative importance of 27 biological, ecological and phylogenetic characteristics of 14 flatfish species on the diversity of their ecto- and endoparasite assemblages, comprising a total of 53 taxa. Redundancy analyses were applied to the mean abundance of each parasite taxa infecting each host and to the richness, taxonomic distinctness and variance in taxonomic distinctness calculated for each assemblage within each host. Only a few host characteristics contributed significantly to the observed patterns: host distribution was more important in determining the type and mean abundance of ectoparasites present in an assemblage, whereas diversity of these assemblages were mainly related to the host's maximum size. Endoparasite mean abundance and diversity were mostly influenced by the number of food items ingested and by the presence of Crustacea and Polychaeta in the diet. However, the sympatric occurrence of related hosts also played an important role in the diversity values found in macroparasite assemblages. Results showed that a host characteristic has different importance according to the host-parasite relationship being examined, suggesting an important role for host-parasite co-evolution on the diversity of extant macroparasite assemblages.

Aggregation patterns of macroendoparasites in phylogenetically related fish hosts.

SUMMARY: Macroparasites are generally aggregated within their hosts with infection and aggregation levels resulting from a continuous arms race between maintaining high mating probability and host mortality low for which host and environmentally related factors contribute to some extent. Here, infection and aggregation patterns of the macroendoparasites infecting the flatfish Citharus linguatula, Arnoglossus laterna, Lepidorhombus boscii, Scophthalmus rhombus and Platichthys flesus in 3 areas along the Portuguese coast were analysed. Of the 21 macroendoparasite species found only 1 infected all hosts and most were host or area exclusive. For each host-parasite system, values of the indices varied between areas and macroendoparasites were not always aggregated; in fact, some macroendoparasites were generally uniformly distributed, which can be related to specific density-dependent regulation mechanisms. No general pattern was found for infection or aggregation levels of the 3 species infecting more than 2 hosts along the Portuguese coast, i.e. Lecithochirium rufoviride, Nybelinia lingualis and Anisakis simplex s.l., suggesting that regulation mechanisms are not species specific but are locally determined, with host ecology playing a significant role.

Impact of discards of beam trawl fishing on the nematode community from the Tagus estuary (Portugal).

The impact of dead discards, originating from beam trawl fishing on the nematode community from the Tagus estuary was investigated in terms of vertical distribution of the dominant nematode groups. Sediment cores were collected from a mud-flat from the Tagus estuary. Crangoncrangon (Linnaeus, 1758) carcasses were added to the surface of the cores, simulating the settling of dead discards on the sediment. The vertical distribution of the dominant nematode groups was determined up to 4cm deep at four different moments in time post deposition (0, 2, 4 and 6h) and compared to control cores. The C.crangon addition to the sediment led to the formation of black spots and therefore oxygen depleted areas at the sediment surface. The Chromadora/Ptycholaimellus group, normally dominant at the surface layer, migrated downwards due to their high sensibility to toxic conditions. Sabatieria presented the opposite trend and became the dominant group at the surface layer. Since Sabatieria is tolerant to oxygen stressed conditions and high sulphide concentrations, we suggest that it migrated opportunistically towards an unoccupied niche. Daptonema, Metachromadora and Terschellingia did not show any vertical migration, reflecting their tolerance to anoxic and high sulphidic conditions. Our study showed that an accumulation of dead discards at the sediment surface might therefore alter the nematode community vertical distribution. This effect is apparently closely related to toxic conditions in the sediment, induced by the deposition of C.crangon at the sediment surface. These alterations might be temporal and reflect an adaptation of the nematode community to dynamic intertidal environments.

Assessing estuarine environmental quality using fish-based indices: performance evaluation under climatic instability.

The seasonal variation of five selected multimetric indices for the determination of the Ecological Quality Status (EQS) of transitional waters was evaluated, as well as the indices' responses to an extreme drought event that occurred in 2005. The database used regards the Mondego River estuary, which was sampled from June 2003 to August 2006 on a monthly basis. Among the selected indices (EBI-Deegan et al. [Deegan, L., Finn, J.T., Ayvazlan, S.G., Ryder-Kieffer, C.A., Buonaccoesi, J., 1997. Development and validation of an Estuarine Biotic Integrity Index. Estuaries 30(3), 601-617], EDI-Borja et al. [Borja, A., Franco, J., Valencia, V., Bald, J., Muxika, I., Belzunce, M.J., Solaun, O., 2004. Implementation of the European Water Framework Directive from the Basque Country (northern Spain): a methodological approach. Marine Pollution Bulletin 48(3-4), 209-218], EFCI-Harrison and Whitfield [Harrison, T.D., Whitfield, A.K., 2004. A multi-metric fish index to assess the environmental condition of estuaries. Journal of Fish Biology 65, 683-710], EBI-Breine et al. [Breine, J.J., Maes, J., Quataert, P., Van den Bergh, E., Simoens, I., Van Thuyne, G., Belpaire, C., 2007. A fish-based assessment tool for the ecological quality of the brackish Scheldt estuary in Flanders (Belgium). Hydrobiologia 575, 141-159] and TFCI - Coates et al. [Coates, S., Waugh, A., Anwar, A., Robson, M., 2007. Efficacy of a multi-metric fish index as an analysis tool for the transitional fish component of the Water Framework Directive. Marine Pollution Bulletin 55, 225-240]), the EBI by Breine et al. (2007) was the only that evidenced clear interannual and seasonal variations. The EQS by the several indices ranged from "Low" to "High", depending on the index considered, evidencing the high level of mismatch between indices. The results are discussed in the scope of the EU Water Framework Directive, regarding monitoring strategies, application of indices and EQS assessment.

Cryptic species of Didymobothrium rudolphii (Cestoda: Spathebothriidea) from the sand sole, Solea lascaris, off the Portuguese coast, with an analysis of their molecules, morphology, ultrastructure and phylogeny.

Didymobothrium rudolphii (Cestoda: Spathebothriidea) was collected seasonally from the sand sole, Solea lascaris, off the northern, central and southern areas of the Portuguese coast. Morphological and molecular analyses were conducted in order to examine the possible existence of cryptic species and to facilitate the circumscription of their morphological boundaries. Data were compared between D. rudolphii specimens from each of the 3 geographical areas and 4 seasons, and principal components analysis of 18 morphological characters was used to detect differences. Two distinct genotypes were present with sequence divergences of 1.9% and 2.1% in the large subunit (lsrDNA) and second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA), respectively. The less common 'central' genotype was present only off the central area from summer to winter, whereas the 'common' genotype was present throughout the year off the northern and southern areas, but only during spring in the central area. No sequence variation was found within each genotype. The presence of 2 distinct genetic entities was supported by morphological analyses, which showed the 'central' genotype specimens to be more slender and elongate, although morphometric ranges overlapped considerably for most characters. Molecular phylogenetic analysis of 4 of the 5 known genera of the Spathebothriidea showed Spathebothrium to be the earliest branching lineage and the 2 genotypes of Didymobothrium formed a sister group to Cyathocephalus. The concordance of genetic differences with variation in host diet according to season and locality could account for sympatric speciation occurring in the central region of the Portuguese coast.

Molecular identification of Anisakis species from Pleuronectiformes off the Portuguese coast.

Anisakid nematodes belonging to the Anisakis simplex complex are highly prevalent in several fish species off the coast of Portugal and are an important zoonotic problem in the Iberian Peninsula. Two reproductively isolated sibling species of the Anisakis simplex complex were identified from Pleuronectiformes inhabiting the Portuguese coast using restriction fragment length polymorphism (RFLP). Recombinant genotypes corresponding to presumptive Anisakis simplex sensu stricto and Anisakis pegreffii hybrids were also detected by this technique, as well as the species Anisakis typica. Although 25 species of Pleuronectiformes were investigated, Anisakis spp. larvae were only found in seven: Arnoglossus imperialis, Arnoglossus laterna, Lepidorhombus boscii, Citharus linguatula, Platichthys flesus, Dicologlossa cuneata and Solea senegalensis. The occurrence of hybrids in relatively sedentary fishes such as the Pleuronectiformes suggests that the Portuguese coast may constitute an area of hybridization and, therefore, is of particular interest for the study of the process of hybridization and speciation for these anisakids.

First record of Progrillotia dasyatidis Beveridge Neifar and Euzet, 2004 (Cestoda: Trypanorhyncha) plerocerci from Teleost fishes off the Portuguese coast, with a description of the surface morphology.

Plerocerci of Progrillotia dasyatidis Beveridge et al. (2004), family Progrillotiidae Palm (2004), are reported from several teleost fishes off the Portuguese coast, giving a first insight into the life cycle biology of these unique trypanorhynchs. The first description and assignment of the plerocercus to P. dasyatidis is based on morphological features, such as scolex and bothria morphology and tentacular hook arrangement, and is expanded to incorporate the surface morphology, examined by scanning electron microscopy, constituting the first ultrastructural study for a species within this family. Comparisons with other species of the genus Progrillotia are made, based on the scolex and bothria morphology and tentacular hook arrangement, in order to give an overview into the variability within this genus, whereas comparisons with adults from the same species evidence the variability within the same species. The systematic approaches of Campbell and Beveridge (1994) and Palm (1997, 2004) are discussed and emphasis is placed on the utility of microtriches and the characteristic life cycle within the genus as systematic characters.