TRENDS IN PORTUGUESE COASTAL FISHERIES LANDINGS: THE ROLE OF HYDROLOGICAL PARAMETERS, OCEANOGRAPHIC FEATURES AND FISHERIES VARIABLES

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Habitat-specific benthic metabolism in a Mediterranean-type intermittent stream

Publication . Sroczynska, Katarzyna; Claro, Marilia; Range, Pedro; Wasiak, Katarzyna; Wojtal-Frankiewicz, Adrianna; Ben-Hamadou, Radhouan; Leitão, Francisco; Chícharo, Luís

A modified flow-through chamber method was used to measure gross primary production (GPP), net primary production (NPP), community respiration (CR) and associated environmental variables in an intermittent Mediterranean-type stream in Southern Portugal. Three common types of in stream habitats were targeted: cobble (C), cobble covered with filamentous algae (C+A) and leaf litter (LL). NPP, GPP and CR differed significantly among all three habitats. GPP increased with chlorophyll a and, less strongly, with photosynthetic active radiation and, therefore, was highest in C+A habitat. The highest CR was in LL and its variation was best determined by ash-free dry mass (AFDM) of plant litter. Higher respiration in LL was related to heterotrophic activity and, to a lesser extent, to autotrophic respiration associated with periphyton. We observed a decrease of production efficiency of primary producers with AFDM in C+A and C habitats. Our results demonstrate that each habitat type should be considered as a discrete metabolic entity and that particular sets of environmental factors are responsible for habitat specific metabolic responses. Scaling up measurements from discrete habitat patches to the entire reach or stream should not be done by extrapolating the results of a single habitat type and will require quantification of habitat coverage, at the appropriate scale.

2016Journal article

Open Access

The Influence of environmental factors and fishing pressure on catch rates of diplodus vulgaris

Publication . Baptista, Vânia; Campos, Carlos J. A.; Leitão, Francisco

The variability of coastal marine resources has been linked to environmental variability but the impacts of artisanal nearshore fishing activity and environmental factors interact in different ways. Time series, Min/Max Autocorrelation Factor, Generalised Least Squares and Dynamic Factor Analyses models were applied to examine the role of environmental factors (SST, NAO Index, Upwelling Index, Wind Magnitude, Easterly Wind Component, Northerly Wind Component, Coastal River Discharges) and fisheries effort on commercial catch rates of Diplodus vulgaris in the Northwest, Southwest and South Portuguese coast. Environmental factors were found to affect short-term variations of catch rates with a time lag of 2 years, according to the regions and seasons. In the Northwest, autumn wind magnitude and summer river discharges were positively correlated with D. vulgaris catch rates. In the Southwest, D. vulgaris catch rates were negatively associated with variations in winter sea surface temperature. In the South, catch rates were positively associated with yearly westerly wind component and yearly, winter and autumn river discharges whilst negatively associated with the North Atlantic Oscillation (NAO) Index. These results indicate that both large-scale climatic patterns and local hydrological factors can have an influential role in determining the abundance of D. vulgaris stocks. Fishery assessment should therefore incorporate information on ecosystem and environmental effects to help managers to make informed decisions on how to best regulate coastal fisheries.

2016-07Journal article

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Independent effects of habitat and stream typology on macroinvertebrate communities in Mediterranean-type intermittent streams

Publication . Sroczyńska, Katarzyna; Leitao, F.; Maximo, I; Range, P.; Furtado, A.; Claro, M.; Chicharo, Luis

Macroinvertebrate-based water quality assessment in temporary streams is an important yet still understudied issue. Investigating different aspects of macroinvertebrate distribution in these streams is therefore highly necessary for the successful implementation of bio-assessment programs. We investigated the variability in macroinvertebrate communities (number of families, abundance, taxonomic richness) and water quality index among six different habitat types (boulder, cobble, gravel, sand, macrophytes, particulate organic matter) and four stream typologies (medium-large southern rivers; southern mountainous rivers; small southern rivers; calcareous rivers). Samples were collected at 32 intermittent and 4 permanent sites in Mediterranean-type streams. The structure of benthic communities showed differences among both habitats and typologies, but there was no interaction among these two factors, indicating that the effect of stream typology does not depend on the habitats that are present in the given stream type. Overall community structure was similar among mineral substrates and macrophytes, which was also reflected in low number of taxa with significant indicator values suggesting the prevalence of generalist tactic and low selectivity in terms of habitat partitioning at these temporary streams. Much higher number of indicator taxa was found for different stream typologies providing evidence that stream types are better predictor for taxa occurrences than a habitat unit at this scale. Southern mountainous streams hosted the highest number of families with significant Indicator Values suggesting that this typology is important for many families with less generalistic set of traits. This typology must be carefully addressed in monitoring programs for water quality assessment even at such fine scale. Further, we reported significant effects of Habitat and Typology for water quality index. Differences were particularly between gravel and organic or depositional habitats (macrophytes/sand/particulate organic matter). For the typology differences were observed between calcareous and non-calcareous stream types.

2019Journal article

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