Alexandra Chícharo
University of the Algarve
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Featured researches published by Alexandra Chícharo.
Ices Journal of Marine Science | 2003
Miguel B. Gaspar; Francisco Leitão; Miguel N. Santos; Luís Chícharo; M. D. Dias; Alexandra Chícharo; C. C. Monteiro
The white clam Spisula solida is harvested along the entire coast of Portugal using mechanical dredges. In this study, the total direct mortality of the macrobenthic community caused by three types of clam dredges (north dredge—ND, traditional dredge—TD, and the metallic grid dredge—GD) used in the S. solida fishery was determined and compared. The relationship between mortality and catching efficiency for each type of dredge was also assessed. Our results showed significant differences for total direct mortality between the ND and both the GD and TD dredges. This difference was largely attributed to the mortality of animals that died in the dredge track as a direct result of the physical damage inflicted by the dredge passing. It was also found that the damage to uncaught individuals is directly related to gear efficiency. The lower catching efficiency of the ND (64%) led to a higher proportion of damaged individuals being left in the dredge path, when compared with the more efficient GD (98%) and TD (90%) dredges. Short and long-term implications of the impact of dredging on the composition of benthic communities are discussed. From fisheries management and ecological points of view, there are obvious advantages to introduce into the bivalve dredge fisheries more efficient and selective dredges in order to reduce the number of damaged individuals and by-catch, and consequently decreasing the impact on the macrobenthic communities.
Journal of the Marine Biological Association of the United Kingdom | 2002
Luís Chícharo; Alexandra Chícharo; Miguel B. Gaspar; Filipe Alves; J. Regala
Macro and meiobenthic communities of two fishing areas (Vilamoura and Lagos) in the western part of south Portugal (Algarve coast) were analysed. Both locations had been under severe dredge-fishing impact until four years previously. Vilamoura has since continued to be dredged, while fishing activity in Lagos was stopped in 1995 as a response to overfishing. For each location, three replicate areas were analysed at depths of 7–9 m. In each of these areas, 18 quadrats for macrofauna and 12 cores for meiofauna were randomly sampled by SCUBA divers during September 1999. The Shannon–Weiner diversity index was higher for meiofauna in the fished area, whereas macrofauna diversity was higher in the recently non-fished area. Bray–Curtis dissimilarity between the two areas was 87·82%. Major differences were found between Ampeliscidea, Amphiura mediterranea , Spisula solida , Haustoriidae, Nemertinea and Diogenes pugilator populations at the two sites. There was higher abundance but lower biomass of potential macrofaunal scavengers in the fished area, and carnivore biomass was also higher in this area. Deposit-feeders dominated meiofauna abundance in both study areas. The community structure of the continuously fished area was dominated by small, opportunistic, short-lived species while the community structure of the recently non-fished area was dominated by more fragile and long-living sessile organisms.
Hydrobiologia | 2001
Miguel B. Gaspar; M. D. Dias; A. Campos; Carlos C. Monteiro; Miguel N. Santos; Alexandra Chícharo; Luís Chícharo
To evaluate a possible introduction of a new dredge in the fishery of Callista chione (Linnaeus, 1758), IPIMAR has conducted a study with the objective of comparing the efficiency of two dredges (traditional dredge and the new dredge design) and evaluating their impact on the benthic community. The experiments were carried out during March 1999 on the Southwest coast of Portugal, from a site off Troia. Three different tow durations of 5, 10 and 20 min were investigated. A total of 24 hauls were accomplished, 4 for each tow duration and dredge. The experiments were conducted by attaching a cover bag with a 20 mm mesh to the gear. After each haul, the catches in the bag and in the cover were sorted separately. All individuals retained were attributed scores on a scale of 1–4 in which 1 equates to good and 4 equates to dead. The results obtained showed that catches from the traditional dredge (TD) are composed of a great fraction of juveniles of C. chione, while in the new dredge (NDD) catches are composed, almost entirely, by individuals with a superior size to the minimum legal length (50 mm). This result indicates that the mesh of the bag of the TD used in the exploitation of this resource is not adequate. For the 3 different tow durations, the mean fishing yield obtained for the NDD was always superior to the TD, due to its greater efficiency in capture. The proportion of by-catch is significantly higher when the TD is used. For all 3 tow duration, the TD caused mortalities on the target species and on the macrobenthic community in the same order of magnitude as the NDD. Since the fishery of C. chione is managed by daily quotas per boat, when using the NDD the impact on the macrobenthic community is reduced by about 50% due to its greater efficiency of capture. Another advantage in the usage of the NDD relatively to the TD, is to allow the smallest individuals (independently of the species) to escape rapidly through the metallic bars on the grid, increasing their probability of survival.
Progress in Oceanography | 2007
A. Miguel P. Santos; Alexandra Chícharo; Antonina dos Santos; Teresa Moita; Paulo B. Oliveira; Álvaro Peliz; Pedro Ré
Estuarine Coastal and Shelf Science | 2006
Ana Margarida Faria; Pedro Morais; Alexandra Chícharo
Ecohydrology and Hydrobiology | 2001
Luís Chícharo; Alexandra Chícharo; Eduardo Esteves; José P. Andrade; Pedro Morais
Estuarine Coastal and Shelf Science | 2007
Rita Alexandra Borges; Radhouan Ben-Hamadou; Alexandra Chícharo; Pedro Ré; Emanuel João Gonçalves
Ices Journal of Marine Science | 2002
Miguel B. Gaspar; Francisco Leitão; Miguel N. Santos; Manuel Sobral; Luís Chícharo; Alexandra Chícharo; Carlos C. Monteiro
Journal of the Marine Biological Association of the United Kingdom | 2003
Miguel B. Gaspar; Miguel N. Santos; Francisco Leitão; Luís Chícharo; Alexandra Chícharo; C. C. Monteiro
Scientia Marina | 2011
Ana Margarida Faria; T. Muha; E. Morote; Alexandra Chícharo