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- Mudflat surface morphology as a structuring agent of algae and associated macroepifauna communities: a case study in the Ria FormosaPublication . Aníbal, J.; Rocha, C.; Sprung, MartinAlthough mudflats seem relatively planar, closer inspection reveals a succession of meso-topographical features, including consecutive convex and concave meso- and micro-topographical features. The objective of this study was to determine the influence of meso-scale surface sediment morphology on the dynamics of the macroalgae Ulvales (Chlorophyta) and associated macroepifauna in the Ria Formosa tidal lagoon (southern coast of Portugal). Four sites in the Ria Formosa were sampled monthly. Two were located on convex sections (mounds) of the mudflat and the other two on concave sections (depressions). Macroalgae and related macroepifauna were sampled at each station. Biomass was quantified by determination of the ash-free dry weight (AFDW). Data were analysed using the software package ‘PRIMER’ (Plymouth Routines In Multivariate Ecological Research). Results show a clear distinction between convex and concave areas. In convex sections, Enteromorpha dominated, to the point of being the only algal species present during part of the year. Conversely, biomass and dynamics of Enteromorpha and Ulva were almost the same in concave sections. The associated macroepifauna was also different in protruding or depressed sections of the mudflat. In the convex areas, the macroepifauna population showed less diversity and was dominated by the snail Hydrobia ulvae. In concave areas, the species diversity was larger, but dominated in terms of biomass by the amphipod Melita palmata and the gastropod Nassarius pfeifferi. Results of the study indicate that the benthic communities associated with concave or convex features were different. No relevant differences in texture and sediment physico-chemical characteristics were found between convex and concave sections. The inference is that the morphological nature of the bottom in tidal mudflats can act as a structuring agent of benthic communities.
- Los gitanos portugueses; marginalidad histórica e segregación contemporáneaPublication . Marques, João FilipeLa primera referencia histórica de la presencia de gitano sen Portugal es, curiosamente, una obra de teatro del siglo XVI: la Farsa das Ciganas de Gil Vicente.
- Weighted Sobolev theorem with variable exponent for spatial and spherical potential operators, IIPublication . Samko, S.; Shargorodsky, E.; Vakulov, B.In [S.G. Samko, B.G. Vakulov, Weighted Sobolev theorem with variable exponent for spatial and spherical potential operators, J. Math. Anal. Appl. 310 (2005) 229-246], Sobolev-type p((.)) -> q((.))-theorems were proved for the Riesz potential operator I-alpha in the weighted Lebesgue generalized spaces L-p(.)(R-n, p) with the variable exponent p(x) and a two-parameter power weight fixed to an arbitrary finite point x(0) and to infinity, under an additional condition relating the weight exponents at x(0) and at infinity. We show in this note that those theorems are valid without this additional condition. Similar theorems for a spherical analogue of the Riesz potential operator in the corresponding weighted spaces L-p(.) (S-n, p) on the unit sphere S-n in Rn+1 are also improved in the same way. (c) 2006 Elsevier Inc. All rights reserved.
- Feeding behavior of Liriomyza huidobrensis (Blanchard) and L. trifolii (Burgess) on bean leavesPublication . Ameixa, Olga; Almeida, Lynette; Gonçalves, Albertina; Neto, LuísThe adult feeding behavior of Liriomyza huidobrensis and L. trifolii was studied in beans of the variety “Catarino.” The insects were placed on a bean leaf and its behavior observed and recorded on DVD for a period of 30 min. An ethogram was constructed based on the different behavior parameters that were identified. The time that each species used in each behavior parameter was registered and compared between the two species. When placed in the arena the two species behaved in a similarmanner, although some differences were observed. The adaptation of the leafminers species to the “Catarino” bean variety under these experimental conditions and the possibility to use some behavioral parameters as indicators of the preference of these insects in relation to the host plant are discussed.