On the assessment of time-shift variations from backscattered ultrasound for large temperature changes in biological phantoms

This work reports the assessment of time-shifts (TS) from backscattered ultrasound (BSU) signals when large temperature variations (up to 15 degrees C) were induced in a gel-based phantom. The results showed that during cooling temperature is linear with TS at a rate of approximately 74 ns/degrees C. However during a complete heating/cooling cycle, the relation is highly non-linear. This can be explained by the fact that during cooling the temperature distribution is more uniform. Another problem to report is that TS is very sensitive to external movements.

Long-term seasonal changes in the abundance of Dendrodoris nudibranchs: a five-year survey

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Changes in physical and chemical parameters of the traditional portuguese product água-mel during the production process

Changes in physical and chemical parameters (viscosity, total soluble solids and Hunter color parameters L*, a*, b*, chroma and hue angle) of água-mel were investigated throughout processing. Kinetic parameters for color change of heatprocessed água-mel were monitored. A zero-order kinetic model was applied to changes in L* and b*, while a* and C* were described using a first-order kinetic model. The heating process changed all three color parameters (L*, a*, b*), causing a shift toward the darker colors. Parameters L* decreased, while a*, b*, C* and hue angle (°h) increased during heating. Regarding changes in total soluble solids and in apparent viscosity, both fitted first-order kinetics. A direct relationship was found between the changes in these two parameters. The increase in both total soluble solids and viscosity affected a*, b* and C*. In addition, a flow diagram for the Portuguese água-mel production process has been established.

Successional dynamics in inland dune shrub communities drive changes in functional diversity

Communities can be defined as assemblages of species coexisting under particular environments. The relationship between environment and species are regulated by both environmental requirements –which ultimately determine the species capacity to establish and survive in a particular environment– and the ecological interactions occurring during assembly processes –which also determine community composition by conditioning species coexistence. In this context, plant functional traits are attributes that represent ecological strategies and determine how plants respond to environmental factors and interact with other species. Therefore, the analysis of how traits vary through the dynamics of communities, such as along successions, can give insights about how environmental requirements and species interactions may determine the composition and functional structure of these communities. The xerophytic shrub communities inhabiting inland sand dunes in SW Portugal are characterized by successional processes that are mainly driven by local (edaphic gradients and human disturbance) and regional (climate) processes. Therefore, they constitute an appropriate system for studying species interactions and environmentcommunity co-variations based on functional terms. Using these communities as a model, we evaluate the hypothesis that successional community changes in species composition of xerophytic shrub communities can result in concurrent changes in functional diversity

Physicochemical and microbiological changes in dried small-spotted catshark (Scyliorhynus canicula): developing an alternative shark-based salted-dried seafood product

A relatively high proportion of harvested seafood is still wasted due to spoilage, particularly in developing countries, or because they are by-catches or have little economic value, seemingly related to inherent problems linked to unattractive color, flavor, texture, small size, and high-fat content. Thus, many fish and seafood species are still underutilized.

Changes in movements of white seabream (Diplodus sargus) during the reproductive season

It has been hypothesized, based on anecdotal information and reports, that adult white seabream migrate and aggregate during spawning. Because most of the past telemetric studies on this ecologically and commercially important species were short in duration and did not cover the reproductive season, we set out to use longer-term passive acoustic telemetry to test this hypothesis. We found that white seabream expands its home range and increases the frequency of forays during the reproductive season, but found no obvious signs of spawning aggregations. Our results thus provide evidence for short-range behavioral shifts in fish space use related to reproductive activity, and support the notion that small MPAs may be effective in managing reef fish populations by effectively protecting their spawning biomass. (c) 2015 Elsevier Ltd. All rights reserved.

Long-term changes in fish communities of the Ria Formosa coastal lagoon (southern Portugal) based on two studies made 20 years apart

Fish communities of the Ria Formosa coastal lagoon (south Portugal) were sampled on a monthly basis with a beach seine at 4 sites, during two different time periods: 1980-1986 and 2001-2002. Community indices, species ranking and multivariate analysis were used in order to identify changes in the fish community between the two time periods. A total of 153,511 fish representing 57 taxa were recorded. Although species composition was very similar for both sampling periods, multivariate analysis performed on annual species abundance in number and weight revealed differences in fish community structure between the two periods. Structural changes in fish community were related mostly to a sharp decrease in the abundance of Mugilidae from 1980-1986 to 2001-2002. These changes were probably associated to a decrease in organic matter contents and nutrients concentrations due to improvements in sewage treatment and better water circulation inside the lagoon. The changes in fish community structure are more evident in the inner areas of the lagoon than near the inlet. The association between changes in sewage patterns and changes in the ichthyofaunal community structure reinforces the importance of fish communities as a biological indicator of human induced changes in marine systems. (c) 2007 Elsevier Ltd. All rights reserved.

Seasonal, tidal and diurnal changes in fish assemblages in the Ria Formosa lagoon (Portugal)

Fish fauna were collected in two different subtidal shallow sites, seagrass and sand, using a small beam trawl in the Ria Formosa lagoon (South Portugal). Samples were taken at low and high tides, during day and night, and in each season. Fish assemblages associated with each site were significantly different, with seagrass site supporting greater fish abundance and higher number of species than sand. These site-related differences in fish assemblages were stronger than any other factor studied. Both sites showed seasonal variations in their fish assemblages, mainly because of recruitment of marine juvenile migrants during spring and summer. No significant tidal or diel changes were observed in the fish assemblages of either site, but there was a significant site-tide interaction, with higher fish abundance in seagrass at low tide. In sand, tide effect was evident only for certain species, with resident species more abundant at high tide and marine species more abundant at low tide. Within the Ria Formosa coastal lagoon, ichthyofaunal composition and structure is mainly influenced by site followed by season. (c) 2005 Elsevier Ltd. All rights reserved.

A conservation trade-off? Interspecific differences in seahorse responses to experimental changes in fishing effort

1. A 2-year experimental seining programme and underwater visual censuses were undertaken to quantify the direct effects of active demersal fishing on the population structure and relative abundance of two sympatric seahorse species of conservation concern: the European long-snouted seahorse, Hippocampus guttulatus Cuvier 1829 and the short-snouted seahorse, Hippocampus hippocampus L. The influence of habitat preference on population-level responses to changes in habitat structure following a reduction in fishing effort was also investigated. 2. It was predicted that the benthic habitat would be more structurally complex after fishing ceased and that seahorse densities would increase in response to reduced fishing mortality. Furthermore, it was predicted that the magnitude of the increase in density would be greater for H. guttulatus than for H. hippocampus, because the former species prefers complex vegetated habitats while the latter species uses sparsely vegetated habitats. 3. As predicted, the amount of habitat cover increased significantly when seining ceased, primarily through increases in the abundance of drifting macroalgae and unattached invertebrates. Despite similarities in life histories, the two seahorse species responded differently in terms of magnitude and direction to reduced fishing effort: the abundance of H. guttulatus increased significantly while H. hippocampus decreased in abundance. 4. Results suggest that active demersal fishing may influence the magnitude and direction of the responses of benthic marine fishes to exploitation through its impacts on habitat structure. An increase in habitat cover appeared to favour higher densities of H. guttulatus when seining effort was reduced. By contrast, repeated seining, which maintained less complex habitats, appeared to favour greater abundances of H. hippocampus. 5. Given differences in habitat preference among benthic marine fishes subject to incidental capture in fisheries, simultaneous attempts to manage populations of sympatric species may require complementary strategies that support the persistence of diverse habitat types. Copyright (c) 2006 John Wiley & Sons, Ltd.