Identification of novel molecular determinants of tissue mineralization in fish

Tese de doutoramento, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015

Long-term changes in fish communities of the Ria Formosa coastal lagoon (southern Portugal) based on two studies made 20 years apart

Fish communities of the Ria Formosa coastal lagoon (south Portugal) were sampled on a monthly basis with a beach seine at 4 sites, during two different time periods: 1980-1986 and 2001-2002. Community indices, species ranking and multivariate analysis were used in order to identify changes in the fish community between the two time periods. A total of 153,511 fish representing 57 taxa were recorded. Although species composition was very similar for both sampling periods, multivariate analysis performed on annual species abundance in number and weight revealed differences in fish community structure between the two periods. Structural changes in fish community were related mostly to a sharp decrease in the abundance of Mugilidae from 1980-1986 to 2001-2002. These changes were probably associated to a decrease in organic matter contents and nutrients concentrations due to improvements in sewage treatment and better water circulation inside the lagoon. The changes in fish community structure are more evident in the inner areas of the lagoon than near the inlet. The association between changes in sewage patterns and changes in the ichthyofaunal community structure reinforces the importance of fish communities as a biological indicator of human induced changes in marine systems. (c) 2007 Elsevier Ltd. All rights reserved.

Short-term hooking mortality of three marine fish species (Sparidae) caught by recreational angling in the south Portugal

Short-term hooking mortality was evaluated for three sparid species [Diplodus vulgaris (Geoffroy Saint-Hilaire), Spar-us aurata L. and Spondyliosoma cantharus (L.)] in the Algarve, south Portugal. Fishes were caught from the shore during October 2009 at a fish farm reservoir (Ria Formosa), using three different hook sizes. The relationships between hooking mortality and seven independent variables were analyzed using logistic regression models. In all,384 fishes representing the three target species were caught during the angling sessions. The most caught species was S. cantharus (n = 181; 100% undersized), followed by S. aurata (n = 137; 89% undersized) and D. vulgaris (n = 66; 97% undersized). Mortalities ranged between 0% for D. vulgaris and 12% for S. aurata (S. cantharus, 3%). For S. aurora, anatomical hooking location was the main predictor of mortality, with 63% of the fishes that died being deeply hooked. Our results support the current mandatory practices of releasing undersized fish for the studied species, given the low post-release mortality rates observed. (C) 2010 Elsevier B.V. All rights reserved.

Environmental influence on commercial fishery landings of small pelagic fish in Portugal

Small pelagic fishes are particularly abundant in areas with high environmental variability (zones of coastal upwelling and areas of tidal mixing and river discharge), and because of this, their abundance suffers large inter-annual and inter-decadal fluctuations. In Portugal, the most important species in terms of landings are European sardine, Atlantic horse mackerel and Atlantic chub mackerel. Small pelagic fish landings account for 62.8 % of the total fish biomass and represent 32.7 % of the economical value of all catches. We have investigated trends in landings of these small pelagic fishes and detected the effects of environmental factors in this fishery. In order to explain the variability of landings of small pelagic fishes, we have used official landings (1965-2012) for trawling and purse seine fisheries and applied generalized linear models, using the North Atlantic Oscillation index (NAO) (annual and winter NAO index), sea surface temperature (SST), wind data (strength and North-South and East-West wind components) and rainfall, as explanatory variables. Regression analysis was used to describe the relationship between landings and SST. The models explained between 50.16 and 51.07 % of the variability of the LPUE, with the most important factors being winter NAO index, SST and wind strength. The LPUE of European sardine and Atlantic horse mackerel was negatively correlated with SST, and LPUE of Atlantic chub mackerel was positively correlated with SST. The use of landings of three important species of small pelagic fishes allowed the detection of variations in landings associated with changes in sea water temperature and NAO index.

Bycatch of crustacean and fish bottom trawl fisheries from southern Portugal (Algarve)

As part of two research projects for analysing bycatch and discards, we quantified catch composition, catch rates, bycatch and discard,, in two important commercial bottom trawl fisheries (crustacean and fish trawls) off the Southern coast of Portugal (Algarve). Stratified sampling by onboard observers took place from February 1999 to March 2001 and data were collected from 165 tows during 52 fishing trips. Commercial tat-get species included crustaceans: blue and red shrimp (Aristeus antennatus), deep-water rose shrimp (Parapenaeus longirostris), Norway lobster (Nepharops norvegicus); and fishes: scabreams (Diplodus spl). and Pagellus Spp.), horse Mackerels (Trachurus spp.) and European hake (Merluccius merluccius). The trawl fisheries are characterised by considerable amounts of bycatch: 59.5% and 80.4% of the overall total catch for crustacean and fish trawlers respectively. A total of 255 species were identified, which belonged to 15 classes of organisms ( 137 vertebrates, 112 invertebrates and algae). Crustacean trawlers had higher bycatch biodiversity. Bony fish (45.6% and 37.8%) followed by crustaceans (14.6% and 11.5%) were the dominant bycatch components of both crustacean and fish trawlers respectively. The influence of a number of factors (e.g. depth, fishing gear, tow duration and season) on bycatch and discards is discussed.

Early reserve effects linked to small home ranges of a commercial fish, Diplodus sargus, Sparidae

Studies that combine both the ecological responses of marine species and protection measures with movement patterns and habitat use are of major importance in order to better understand the performance of marine protected areas (MPA) and how species respond to their implementation. However, few studies have assessed MPA performance by relating local individual movement patterns and the observed reserve effects. In this study, we combined acoustic telemetry with abundance estimates to study the early effects of a recently established small coastal MPA on the local populations of white seabream. The results show that even small, recently established coastal MPAs can increase the abundance and biomass of commercial fish species, provided that target species have small home ranges and exhibit high site fidelity.

Robustness of the Estuarine Fish Assessment Index (EFAI) regarding water body definition criteria

According to the Water Framework Directive (WFD) transitional waters should be differentiated according to type and, in some cases, divided into different water bodies. This raises a dilemma in trying to define parts of a continuum. In the sequence of WFD several indices have been proposed including the Estuarine Fish Assessment Index, which can be applied taking an estuary as a whole (EFAI - without water bodies division) or divided in water bodies (EFAI(WB)). The purpose of this work is to analyze the robustness of the Estuarine Fish Assessment Index, based on three different ways of dividing Portuguese estuaries into water bodies according to different criteria (criterion 1 - distance to the estuary mouth, criterion 2 - salinity and criterion 3 - morphology, salinity and human dimension as pressure and state). In this study we evaluated at which degree these three criteria could influence the ecological quality ratio (EQR) results, when the index was applied to water body level (EFAI(WB)). Also, for each estuary, the EQR(WB) results for each criterion of EFAI(WB) were combined and weighted according to the water bodies areas (EFAI overall weighted - EFAI(Ow)). Finally, it was compared if the results obtained for each criterion with the EFAI(OW) were similar to the results of the index application taking the estuary as a whole (EFAI without water bodies division). No significant differences were found in both cases, which indicated that this index is a robust method regarding the division of the estuaries in different water bodies, which is an important element of a fish-based multimetric tool for assessing estuarine ecological quality. However, in some cases, different ecological quality statuses were achieved when applying the EFAI(Ow) or the EFAI. This work addressed several aspects regarding the possible division of water bodies at the WFD context. (C) 2012 Elsevier Ltd. All rights reserved.

Seasonal, tidal and diurnal changes in fish assemblages in the Ria Formosa lagoon (Portugal)

Fish fauna were collected in two different subtidal shallow sites, seagrass and sand, using a small beam trawl in the Ria Formosa lagoon (South Portugal). Samples were taken at low and high tides, during day and night, and in each season. Fish assemblages associated with each site were significantly different, with seagrass site supporting greater fish abundance and higher number of species than sand. These site-related differences in fish assemblages were stronger than any other factor studied. Both sites showed seasonal variations in their fish assemblages, mainly because of recruitment of marine juvenile migrants during spring and summer. No significant tidal or diel changes were observed in the fish assemblages of either site, but there was a significant site-tide interaction, with higher fish abundance in seagrass at low tide. In sand, tide effect was evident only for certain species, with resident species more abundant at high tide and marine species more abundant at low tide. Within the Ria Formosa coastal lagoon, ichthyofaunal composition and structure is mainly influenced by site followed by season. (c) 2005 Elsevier Ltd. All rights reserved.