Browsing by Author "Chicharo, Luis"
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- Climate change vulnerability assessment of the main marine commercial fish and invertebrates of PortugalPublication . Bueno-Pardo, Juan; Nobre, Daniela; Monteiro, J. N.; Sousa, Pedro M.; Costa, Eudriano; Baptista, Vânia; Ovelheiro, Andreia; Vieira, Vasco; Chicharo, Luis; Gaspar, Miguel; Erzini, Karim; Kay, Susana; Queiroga, Henrique; Teodosio, Maria; Leitão, FranciscoThis is the first attempt to apply an expert-based ecological vulnerability assessment of the effects of climate change on the main marine resources of Portugal. The vulnerability, exposure, sensitivity, adaptive capacity, and expected directional effects of 74 species of fish and invertebrates of commercial interest is estimated based on criteria related to their life-history and level of conservation or exploitation. This analysis is performed separately for three regions of Portugal and two scenarios of climate change (RCP 4.5 and RCP 8.5). To do that, the fourth assessment report IPCC framework for vulnerability assessments was coupled to the outputs of a physical-biogeochemical model allowing to weight the exposure of the species by the expected variability of the environmental variables in the future. The highest vulnerabilities were found for some migratory and elasmobranch species, although overall vulnerability scores were low probably due to the high adaptive capacity of species from temperate ecosystems. Among regions, the highest average vulnerability was estimated for the species in the Central region while higher vulnerabilities were identified under climate change scenario RCP 8.5 in the three regions, due to higher expected climatic variability. This work establishes the basis for the assessment of the vulnerability of the human activities relying on marine resources in the context of climate change.
- Depth segregation phenomenon in Donax trunculus (Bivalvia : Donacidae) populations of the Algarve coast (southern Portugal)Publication . Gaspar, Miguel; Chicharo, Luis; Vasconcelos, P.; Garcia, A; Santos, A. R.; Monteiro, C. C.A study was undertaken to evaluate the existence of depth segregation between size classes of Donax trunculus populations that occur along the Algarve coast (southern Portugal). Five collecting areas were sampled in the Ria Formosa barrier islands, namely in the Culatra, Barreta and Armona Islands, between March and June 1998. The study was based on size frequency distribution analysis and shell biometric relationships, The size frequency distribution showed the predominance of smaller individuals (<25 mm) in the renewal area (0.5-1.0 m depth) and the prevalence of larger individuals (greater than or equal to25 mm) at greater depths (4.0-6.0 in depth). The biometric study revealed the existence of significant differences in the type of growth between size classes in relation to depth distribution and burrowing activity. On the basis of these results, some specific management measures were proposed for this important bivalve fishery, taking into account the distinct fishing strategies and operations (manual and boat-operated dredging) performed at different depths.
- Development of a metric of aquatic invertebrates for volunteers (MAIV): a simple and friendly biotic metric to assess ecological quality of streamsPublication . Pinto, Paulo; Oliveira Junior, José Max; Leitão, Francisco; Morais, Maria M.; Chicharo, Luis; Vaz, Paula; Delgado, Sofia M. A.; Voreadou, Catherina; Morales, Eduardo A.; Teodosio, MariaCitizen science activities, involving local people in volunteer-supported and sustainable monitoring programs, are common. In this context, the objective of the present work was to develop a simple Metric of Aquatic Invertebrates for Volunteers (MAIV), including a user-friendly tool that can be easily accessed by volunteers, and to evaluate the e ciency of a volunteer monitoring program following an audit procedure. To obtain MAIV values, macroinvertebrate communities were reduced to 18 surrogate taxa, which represented an acceptable compromise between simplicity, e ciency, and reproducibility of the data, compared to the regular Water Framework Directive monitoring. When compared to results obtained with the National Classification System of Portugal, MAIV accurately detected moderate, poor, and bad ecological status. Thus, MAIV can be used by volunteers as a complement to the o cial monitoring program, as well as a prospective early warning tool for local problems related to ecological quality. Volunteers were students supervised by their teachers. Results obtained by volunteers were compared to results obtained by experts on macroinvertebrate identification to measure the e ciency of the procedure, by counting gains and losses on sorting, and identification. Characteristics of groups of volunteers (age and school level) did not influence significantly the e ciency of the procedure, and generally results of volunteers and experts matched.
- Environmental factors affecting larval fish community in the salt marsh area of Guadiana estuary (Algarve, Portugal)Publication . Gonçalves, Renata; Correia, Ana Dulce; Atanasova, Natasa; Teodosio, Maria; Ben-Hamadou, Radhouan; Chicharo, LuisSalt marsh areas in the Guadiana estuary are important nursery sites for many fish species of commercial and recreational value. More effective protection measures should be adopted as the area is highly affected by anthropogenic and natural threats. Studying larval fish communities in these impacted nursery areas will be relevant to the management of local ecosystems and to larval fish ecology in general. Spatial and seasonal distribution and the effect of environmental factors on the larval fish community of this ecosystem were studied for one year (April 2010 to March 2011). Larvae were sampled monthly in parallel with phytoplankton and zooplankton. Hydrological data and physical parameters were monitored. A decision tree model was used to assess the influence of environmental factors on the larval fish community. A total of 130 larvae and 1171 eggs were caught. Diplodus sargus, Sardina pilchardus, and Pomatoschistus microps were the most abundant larval fish species. The peaks of fish larvae abundance occurred in March and April. The output of the model demonstrates that the abundance of larval fish is determined by the abundance of eggs, zooplanktonic food, and water flood and flow. This study shows the importance of the Guadiana salt marsh as an area for fish nursery and highlights the need for conservation of this area.
- Ervilia castanea (Mollusca, Bivalvia) populations adversely affected at CO2 seeps in the North AtlanticPublication . Martins, Marta; Carreiro-Silva, Marina; Martins, Gustavo M.; Barcelos e Ramos, Joana; Viveiros, Fátima; Couto, Ruben P.; Parra, Hugo; Monteiro, João; Gallo, Francesca; Silva, Catarina; Teodosio, MA; Guilini, Katja; Hall-Spencer, Jason M.; Leitão, Francisco; Chicharo, Luis; Range, PedroSites with naturally high CO2 conditions provide unique opportunities to forecast the vulnerability of coastal ecosystems to ocean acidification, by studying the biological responses and potential adaptations to this increased environmental variability. In this study, we investigated the bivalve Ervilia castanea in coastal sandy sediments at reference sites and at volcanic CO2 seeps off the Azores, where the pH of bottom waters ranged from average oceanic levels of 8.2, along gradients, down to 6.81, in carbonated seawater at the seeps. The bivalve population structure changed markedly at the seeps. Large individuals became less abundant as seawater CO2 levels rose and were completely absent from the most acidified sites. In contrast, small bivalves were most abundant at the CO2 seeps. We propose that larvae can settle and initially live in high abundances under elevated CO2 levels, but that high rates of post-settlement dispersal and/or mortality occur. Ervilia castanea were susceptible to elevated CO2 levels and these effects were consistently associated to lower food supplies. This raises concerns about the effects of ocean acidification on the brood stock of this species and other bivalve molluscs of similar life history traits.
- Fish communities and environmental variables during dry season in Pampanga estuary (Philippines)Publication . Abroguena, Jeff Bogart R.; Range, Pedro; Cruz, Wilfredo; Tentia-Lagumen, Mary Chris; Chicharo, LuisBaseline assessment of fish communities and selected environmental variables (salinity, water temperature, water transparency, current speed, total suspended solid, chlorophyll a) was conducted in Pampanga estuary (Philippines) during a specific dry season (April 2010). The aims were: (a) to examine the variations of fish diversity and community structure, in relation to neap and spring tides and estuary zones and; (b) to examine the influence of environmental variables on fish communities. Reconnaissance showed that salinity was measurable at 6.8 kilometers from the rivermouth, for the surface and mid-water layers, and at 15.9 kilometers for the bottom layers, indicating the occurrence of a salt wedge. Bottom salinity was used to establish the sampling stations, grouped into 3 zones (lower 1-3, middle 4-6, upper 7-9). Sampling of fish, using otter trawl, and measurement of environmental variables were done under four tidal conditions at each station (neap low and high tide; spring low and high tide). Neap tide showed low and homogenous horizontal salinity, higher temperature, slower current speed, high TSS and chlorophyll a, whereas, spring tide showed higher salinity, horizontal saline stratification, lower temperature, faster current speed, low TSS and chlorophyll a. A total of 330 fish were captured from 32 trawl samples, encompassing 20 families and 27 species. Number of species generally did not vary between neap (20) and spring tide (18), but showed a decreasing pattern from lower to the upper estuary. Only 36% of total species were shared between neap and spring tides. Fish abundance was significantly affected by neap and spring tide, and zonation, whereas fish biomass was solely affected by zonation. Arius manillensis was the most typifying species, suggesting high probability of encounter. Chlorophyll a, TSS, salinity and current speed have a significant influence on the variations of abundance, biomass and frequency of occurrence of particular fish species. (C) 2020 Elsevier B.V. All rights reserved.
- Impact of heavy metals of industrial plant wastewater on benthic communities of Bizerte Lagoon (Tunisia)Publication . Saidi, Ibtihel; Ben Said, Olfa; Ben Abdelmalek, Jamel; Jouili, Soufiane; Chicharo, Luis; Beyrem, HamoudaThe aim of this study was to assess the consequences of human impact on the characteristics of sediments heavy metal concentration, grain size and its influence on the structure of the microbial and meiofaunal community assemblages. A survey was carried out in July 2013 within six sites located in the Bizerte Lagoon (Tunisia), both downstream and upstream of industrial effluents. The highest total sediment metal concentrations were detected in stations located close to the industrial sewage discharge points. In these stations, the lowest densities of the total meiofauna (33 +/- 13 ind/10 cm(-2)) and conversely the highest densities of cultivable bacteria that are heavy metal resistant have been reported (16 +/- 80.34 CFU g(-1)). Univariate (ANOVA) and multivariate (MDS/CCA) analyses demonstrate high dissimilarity (0.06) in meiofaunal and bacterial community structures between downstream and upstream industrial sewages. Furthermore, canonical correspondence analysis CCA results indicated that heavy metal sediment contamination promoted bacteria that are resistant to heavy metals, while heterotrophic bacteria supported the development of meiofauna taxa. The results highlight the importance of bacteria/meiofauna interactions, as both meiofaunal and microbial communities give indications of the ecological impact of heavy metal contamination in sediment.
- Importância das plantas do sapal para reter os metais que chegam à Ria Formosa devido às atividades humanasPublication . Silva, Manuela; Duarte, D. N.; Chicharo, LuisOs sapais são ecossistemas costeiros, na transição entre a terra e o mar, que se caracterizam por ser colonizados por plantas vasculares superiores, herbáceas e arbustivas, que apresentam grande resistência à salinidade, e que por isso se designam de halófitas. Estas plantas desenvolveram ao longo do tempo estratégias de adaptação, que lhes permitem resistir a períodos de submersão, mais ou menos longos, consoante se localizam em baixo, médio ou alto sapal.
- Independent effects of habitat and stream typology on macroinvertebrate communities in Mediterranean-type intermittent streamsPublication . Sroczyńska, Katarzyna; Leitao, F.; Maximo, I; Range, P.; Furtado, A.; Claro, M.; Chicharo, LuisMacroinvertebrate-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.
- Indicator macroinvertebrate species in a temporary Mediterranean river: recognition of patterns in binary assemblage data with a Kohonen artificial neural networkPublication . Sroczyńska, Katarzyna; Claro, M.; Kruk, A.; Wojtal-Frankiewicz, A.; Range, P.; Chicharo, LuisCurrent classifications used in bioassessment programs, as defined by the Water Framework Directive (WFD), do not sufficiently capture the variability present in temporary Mediterranean streams. This may result in inaccurate evaluation of the water quality biological metrics and difficulties in setting reference conditions. The aim of the study was to examine if aquatic invertebrate data of increased taxonomical resolution but expressed on a binary abundance (frequent/rare) scale and referring to good bioindicator species only suffice to indicate clear gradients in water courses with high natural variability such as intermittent Mediterranean streams. Invertebrate samples were collected from 74 sites in the Quarteira River basin, located in southern Portugal. Their classification with the use of a Kohonen artificial neural network (i.e., self-organising map, SOM) resulted in five categories. The variables that drove this categorization were primarily altitude, temperature and conductivity, but also type of substrate, riparian cover and percentage of riffles present. According to the indicator species analysis (ISA), almost all the studied taxa were significantly associated with certain SOM categories except for the category that included sites with disrupted flow regime. The SOM and ISA allowed us to effectively recognize biotic and abiotic patterns. Combined application of both methods may thus greatly enhance the effectiveness and precision of biological surveillance and establish reference sites for specific channel units in streams with high natural variability such as intermittent Mediterranean streams. (C) 2016 Elsevier Ltd. All rights reserved.