Fish assemblages of shallow intertidal habitats of the Ria Formosa lagoon (South Portugal): influence of habitat and season

Fish assemblages in seagrass and unvegetated habitats located in shallow intertidal creeks within the saltmarsh area of the Ria Formosa coastal lagoon were sampled with a Riley push net at 3 sites on a monthly basis over a 1 yr period. The objective was to test if both habitats support similar fish assemblages in terms of abundance, diversity, assemblage structure, and size distribution, and to investigate how site and season affect the assemblages. Fish assemblages associated with these habitats were significantly different in terms of diversity, abundance, and assemblage structure. Seagrass supported a larger number of species and greater diversity, while unvegetated habitat supported greater fish numbers but only of a few species. The habitats were dominated by different groups of resident species that were responsible for major differences in fish assemblage structure between habitats. Pomatoschistus microps and young-of-the-year (YOY) Atherina presbyter dominated the unvegetated habitat, while seagrass was dominated by a diverse group of species, in particular syngnathids and small labrids, revealing different habitat preferences. Site and season were determinant factors conditioning the role of habitat in structuring fish assemblages. Distance between habitats, site elevation, and the amount of marsh drained affected fish assemblages in both habitats. Seasonal fluctuations in the presence and abundance of YOY from marine migrant and resident species were responsible for comparable changes in fish assemblage structure in both habitats. Both habitats provide a distinctive nursery area for different species, while common species reveal ontogenic distributional changes between habitats, where smaller fish appear first in unvegetated creeks.

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.

Trophic food web and ecosystem attributes of a water reservoir of the Ria Formosa (south Portugal)

Using a top-down modelling approach, a balanced trophic food web model of a water reservoir of the Ria Formosa lagoonal system was constructed. Few adjustments of input data were necessary to run the model since most of the parameters were estimated at the study site and the characteristics of the water reservoir allowed a high degree of control and precision in terms of sampling and data collection. Trophic levels of the 14 compartments included in the model varied between 1.0 for primary producers and detritus to 3.4 for carnivorous fish and the 14 groups were aggregated in a food chain with six trophic levels. The water reservoir has a detritus based food chain, with the majority of the biomass concentrated in the first two levels, the producers level and the herbivore/detritivore level (97.6%). The transfer efficiencies were low, and decreased with increasing level number, varying between 6.0 and 0.2%. The degree of "ecosystem maturity" was difficult to establish, but several parameters indicate that it could be high. The water reservoir studied, which has similar environmental and ecological characteristics as the Ria Formosa lagoon. is near its carrying capacity. (C) 2004, Elsevier B.V. All rights reserved.

First record of the Mediterranean parrotfish, Sparisoma cretense in Ria Formosa (south Portugal)

Several juvenile specimens of Sparisoma cretense, a previously unrecorded species, were caught using beach seining in Ria Formosa.The hypothesis that these occurrences are related with climatic changes is discussed.

Age and growth, mortality and reproduction of the striped sea bream, Lithognathus mormyrus Linnaeus 1758, from the south coast of Portugal (Algarve)

The striped sea bream, Lithognathus mormyrus, used for this population dynamics study were obtained from longline catches and market sampling in the Algarve (south Portugal). The macroscopic analysis of the gonads and the gonad somatic index showed that the south Portuguese population of L. mormyrus spawns mainly between late spring and summer (June to August). The length at first maturity was similar for males and females and the value for both sexes combined was estimated to be 16.08 cm, corresponding to an age between 1 and 2 years. Fish age classes (0 to 13) were determined by reading growth rings on whole otoliths. Age determination was validated by marginal increment analysis. The estimated parameters of the von Bertalanffy growth equation were L infinity = 35.30 cm, K = 0.264 and t(0) = -0.809. Mortality rates were calculated for fish captured with longlines, and the estimated parameters were M = 0.356, Z = 0.622 and F = 0.266. From an Algarve fishery management perspective, these results suggest the need for an increase in the minimum landing size (from 15 to 17 cm), which should be beneficial for the sustainability and conservation of this species. The results also showed that fishing with longlines off the Algarve coast may allow for a sustainable use of the resource.

Reproductive aspects of the undulate ray, Raja undulata, from the south coast of Portugal

The maturity of the undulate ray, Raja undulata, one of the most important by-catch elasmobranch species captured in south Portugal, was studied for the first time. Females ranged in total length (TL) from 19.4 to 88.2 cm and males from 23.0 to 83.2 cm. The gonadosomatic index for females was higher during the winter, meaning that this species reproduces during this season. Females matured at significantly larger sizes and older ages than males, with 50% of the females mature at 76.2 cm TL at an age of 8.98 years while 50% maturity for males was achieved at 73.6 cm TL and 7.66 years. Females were mature at 86.3% of the maximum observed size and 69.1% of the maximum observed age while males matured at 88.5% of the maximum observed size and 63.8% of the maximum observed age, making this a very late maturing species, with important consequences in terms of fisheries management and conservation. (c) 2006 Elsevier B.V. All rights reserved.

First record of Anachis aliceae (Mollusca: Gastropoda: Columbellidae) in the Algarve, south coast of Portugal

The marine gastropod Anachis aliceae (Pallary, 1900) is reported with certainty for the first time from the Algarve, south coast of Portugal from species-rich rocky priority biotope. Several live specimens of this species belonging to the Columbellidae family were collected and identified from by-catch samples, recovered from octopus traps set at depths between 50 and 70 m off Ponta da Piedade. Taxonomic validation of the newly recorded species is based on the comparison to other related species within the genus.

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.

Reduction of elasmobranch by-catch in the hake semipelagic near-bottom longline fishery in the Algarve (Southern Portugal)

Elasmobranch fish, particularly deep-sea sharks, are the most important component of the by-catch of the hake semipelagic near-bottom 'pedra-e-bola' longline fishery in the Algarve (South Portugal) and most of these fish are discarded. The effects of the removal of the lower hooks were evaluated, in terms of target and by-catch reductions, by quantifying the catches of each hook relative to the distance from the bottom. The analysis showed that most European hake (Merluccius merluccius), the target species of this fishery, were caught in the middle range of the hooks, with very few individuals caught near the bottom, whereas for sharks the situation was the opposite, with most hooked near the bottom. The removal of the lower three pairs of hooks would result in a small reduction in the catch of the target species, but a much more significant reduction in elasmobranch by-catch. In the specific case of the blackmouth catshark (Galeus melastomus), discard mortality would be further minimized due to the fact that the lower hooks capture significantly smaller animals that are always discarded compared with hooks that are more distant from the bottom.

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.

First record of Calcinus tubularis on the southern coast of Portugal (Crustacea: Decapoda: Anomura: Diogenidae)

Twenty-five specimens of the hermit crab Calcinus tubularis were observed during SCUBA dives for fauna and flora assessment in the shallow rocky reefs of the southern coast of Portugal between 2003 and 2008. Of the specimens observed, only one specimen used a tube gallery, while the others occupied unidentified gastropod shells with strong bio-cover. Calcinus tubularis is here recorded from the mainland Portuguese coast for the first time. This is the first record of the species in European coastal waters outside the Mediterranean Sea (excluding the Atlantic Islands) and extends the known geographical distribution of the species further north in the north-eastern Atlantic.

Spatial and depth-associated distribution patterns of shallow gorgonians in the Algarve coast (Portugal, NE Atlantic)

The ecological role of gorgonians for marine rocky bottoms is worldwide recognized, but the information on the distribution patterns of NE Atlantic temperate species is insufficient, considering current global, regional and local threats. To overcome the lack of information on the spatial distribution patterns of gorgonians in south Portugal, in 2009/2010, the occurrence and abundance of gorgonian species in rocky bottoms were quantified over more than 25 km of coast (37.1N/8.6W) down to 30 m depth. Eunicella labiata, Eunicella gazella, Eunicella verrucosa and Leptogorgia sarmentosa were abundant and frequent in the studied area, while Leptogorgia lusitanica was less abundant. All species evidenced a similar depth pattern, that is abundance significantly increased with depth below 15 m. At shallower waters (up to 15 m), the distribution of gorgonians may be constrained by abiotic factors and competition with algae. Indeed, the abundance of gorgonians was negatively correlated with the percentage cover of algae along the depth gradient, but gorgonians and sponges coexist. Competition among gorgonian species also seems to be low in this area because of the similarity in the abundance pattern observed for the most abundant species and also their high association. In NE Atlantic shallow temperate rocky bottoms, the distribution of gorgonians seems to be influenced by environmental factors and biological interactions, namely competition (algae) and coexistence (sponges and other gorgonians).

Tecnologia e funcionalidade das peças esquiroladas do Paleolítico Superior de Vale Boi, Vila do Bispo

Dissertação de Mestrado, Arqueologia, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2016

Genetic diversity across geographical scales in marine coastal ecosystems: Holothuria arguinensis a model species

Coastal lagoons are considered one of the most productive areas of our planet harboring a large variety of habitats. Their transitional character, between terrestrial and marine environments, creates a very particular ecosystem with important variations of its environmental conditions. The organisms that are able to survive on these ecosystems frequently experience strong selective pressures and constrictions to gene flowwith marine populations, which could contribute to genetic divergence among populations inhabiting coastal lagoon and marine environments. Therefore, the main aims of this study are to asses the genetic diversity and population structure of Holothuria arguinensis across geographical ranges, to test the hypothesis of coastal lagoons as hotspots of genetic diversity in the Ria Formosa lagoon, and to determine the role of exporting standing genetic variation from the lagoon to open sea and their implications to recent geographical expansion events. To reach these objectives, we investigate the genetic structure of H. arguinensis using two mitochondrial DNA markers (COI and 16S) at different spatial scales: i) small, inside Ria Formosa coastal lagoon, South Portugal; 2) large, including most of the geographical distribution of this species (South and Western Portuguese coast and Canary islands); these results will allow us to compare the genetic diversity of lagoonal and marine populations of H. arguinensis. On this framework, its recent geographical expansion events, recorded by Rodrigues (2012) and González-Wangüemert and Borrero-Pérez (2012), will be analyzed considering the potential contribution from lagoonal genetic pool. Non-significant genetic structure and high haplotypic diversity were found inside the Ria Formosa coastal lagoon. Both genes were unable to detect significant genetic differentiation among lagoonal and marine localities, suggesting a high rate of gene flow. The results supported our hypotheses that coastal lagoons are not only acting as hotspots of genetic diversity, but also contributing for the genetic variability of the species, working as a source of new haplotypes and enhancing adaptation to the high variable conditions. Different genetic patterns of colonization were found on H. arguinensis, but they must be studied more deeply.

Ecotourism snorkelling routes at Marinha Beach (Algarve)

Coastal ecotourism is one of the fastest growing leisure industries in the world and snorkelling is emerging as an important beach-based activity. Snorkelling has the potential to enhance biodiversity conservation when developed within environmental education framework. The aim of this study was to implement and evaluate snorkelling routes, in the Algarve (South Portugal), as a sustainable ecotourism offer. To achieve these objectives, three snorkelling routes were established at the pristine Marinha beach. After the diving experience, a face-to-face questionnaire survey was conducted to collect information about individuals' opinions regarding the underwater routes, their social demographic characteristics, ecological appreciation, opinions about beach facilities and trip expenditures. The survey was undertaken during the summer months of 2008 and 2009, and 202 people were interviewed. Data was analysed using univariate and multivariate statistic methods. Most respondents perceived the existence of routes to be good for the preservation of the local biodiversity and reported this experience as "good" or "excellent". The only difference in perceptions was observed by visitor snorkelling in groups of more than two people. Interviewers consider that emergency support and sanitary facilities are the most important beach support infrastructures. Overall, these routes seem to be an effective tool for developing ecological awareness in tourists, as they enhance the preservation and the understanding of the marine coastal environment.