Large-scale prediction of seagrass distribution: the case of Cymodocea nodosa (Mediterranean-Atlantic)

Understanding the factors that affect seagrass meadows encompassing their entire range of distribution is challenging yet important for their conservation. We model the environmental niche of Cymodocea nodosa using a combination of environmental variables and landscape metrics to examine factors defining its distribution and find suitable habitats for the species. The most relevant environmental variables defining the distribution of C. nodosa were sea surface temperature (SST) and salinity. We found suitable habitats at SST from 5.8 ºC to 26.4 ºC and salinity ranging from 17.5 to 39.3. Optimal values of mean winter wave height ranged between 1.2 m and 1.5 m, while waves higher than 2.5 m seemed to limit the presence of the species. The influence of nutrients and pH, despite having weight on the models, was not so clear in terms of ranges that confine the distribution of the species. Landscape metrics able to capture variation in the coastline enhanced significantly the accuracy of the models, despite the limitations caused by the scale of the study. By contrasting predictive approaches, we defined the variables affecting the distributional areas that seem unsuitable for C. nodosa as well as those suitable habitats not occupied by the species. These findings are encouraging for its use in future studies on climate-related marine range shifts and meadow restoration projects of these fragile ecosystems.

Integrated multi-scale architecture of the cortex with application to computer vision

Tese de dout., Engenharia Electrónica e de Computadores, Faculdade de Ciência e Tecnologia, Universidade do Algarve, 2007

Dispersal, sex ad clonality in the marine environment: population genetic structure of the seagrass Cymodocea nodosa on Mediterranean and Atlantic coasts

Dissertação de dout. em Ecologia, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2005

Population structure of the black seabream Spondyliosoma cantharus along the south-west Portuguese coast inferred from otolith chemistry

The chemistry of black seabream Spondyliosoma cantharus otoliths from three main fishery grounds (Olhao, Sagres and Sesimbra) located along c. 400 km of the Portuguese south and west coasts was examined. Element:Ca ratios were determined in whole otoliths and otolith cores of young adult specimens of 23 years of age. Using the data from whole otoliths, it was possible to discriminate among S. cantharus from the three fishing grounds with an average accuracy of 91%. Differences among fishing grounds were significant for all element:Ca ratios, and otoliths from Sagres had significantly higher levels of all ratios compared to the other fishing grounds. In contrast, the chemical composition of the otolith core, representative of the larval stage, showed limited variation among the fishing grounds, with an average discrimination accuracy of only 44%, although the Mg:Ca ratio of the otolith cores was also significantly higher for the Sagres samples. The data suggest that larval stages experienced a homogenous environment consistent with an offshore oceanic spawning. Juveniles appeared to display local residency on the inshore fishing grounds, areas probably characterized by greater environmental heterogeneity. Spondyliosoma cantharus population structure is consistent with distinct local population units that share a spawning ground providing recruits to different coastal fishery areas.