Elemental and spectral chemometric analyses of Octopus vulgaris beaks as reliable markers of capture location.

The high demand and economic relevance of cephalopods make them prone to food fraud, including related to harvest location. Therefore, there is a growing need to develop tools to unequivocally confirm their capture location. Cephalopod beaks are nonedible, making this material ideal for traceability studies as it can also be removed without a loss of commodity economic value.

Elemental Fingerprinting of Wild and Farmed Fish Muscle to Authenticate and Validate Production Method.

In the context of expanding fish production and complex distribution chains, traceability, provenance and food safety tools are becoming increasingly important. Here, we compare the elemental fingerprints of gilthead seabream () muscle from wild and different aquaculture productions (semi-intensive earth ponds and intensive sea cages from two locations) to confirm their origin and evaluate the concentrations of elements with regulatory thresholds (Cu, Hg, Pb and Zn). Using a chemometric approach based on multi-elemental signatures, the sample origin was determined with an overall accuracy of 90%.

Harnessing the Full Power of Chemometric-Based Analysis of Total Reflection X-ray Fluorescence Spectral Data to Boost the Identification of Seafood Provenance and Fishing Areas.

Provenance and traceability are crucial aspects of seafood safety, supporting managers and regulators, and allowing consumers to have clear information about the origin of the seafood products they consume. In the present study, we developed an innovative spectral approach based on total reflection X-ray fluorescence (TXRF) spectroscopy to identify the provenance of seafood and present a case study for five economically relevant marine species harvested in different areas of the Atlantic Portuguese coast: three bony fish-, , and ; one elasmobranch-; one cephalopod-. Applying a first-order Savitzky-Golay transformation to the TXRF spectra reduced the potential matrix physical effects on the light scattering of the X-ray beam while maintaining the spectral differences inherent to the chemical composition of the samples.

Assessing spatio-temporal changes in marine communities along the Portuguese continental shelf and upper slope based on 25 years of bottom trawl surveys.

The Portuguese continental coast is influenced by several oceanographic processes and is located near the confluence of three biogeographic realms (from the North Atlantic, South Atlantic and Mediterranean). Given these features, the topography of the Portuguese coast, possible variations in fishing effort and reported increasing sea surface temperature in the last decades, we hypothesized that changes in marine communities in space and time occurred since 1990. In this study, research survey data collected yearly along the Portuguese continental slope (20-500 m deep) from 1990 to 2016 were analysed with the objective of identifying spatio-temporal changes.

Extrinsic and intrinsic factors shape the ability of using otolith chemistry to characterize estuarine environmental histories.

Reconstructing habitat use and environmental histories of fish via otolith chemistry relies on linking otolith chemical composition to the surrounding environment, as well as disentangling the consequences of ontogenetic or physiological effects that may mask environmental signals. We used multiple linear and linear mixed models to analyse the importance of environmental (temperature, salinity, water chemistry) and individual based (fish size) factors on otolith chemical composition and incorporation (Li, Mg, Mn, Sr, and Ba) of juvenile Dicentrarchus labrax, over their time within an estuarine nursery area. Multi model inference highlighted the importance of ontogeny, as well as the influence of temperature and salinity on otolith chemistry and elemental incorporation, with results indicating that intrinsic effects may potentially outweigh environmental effects.

Reconciling differences in natural tags to infer demographic and genetic connectivity in marine fish populations.

Processes regulating population connectivity are complex, ranging from extrinsic environmental factors to intrinsic individual based features, and are a major force shaping the persistence of fish species and population responses to harvesting and environmental change. Here we developed an integrated assessment of demographic and genetic connectivity of European flounder Platichthys flesus in the northeast Atlantic (from the Norwegian to the Portuguese coast) and Baltic Sea. Specifically, we used a Bayesian infinite mixture model to infer the most likely number of natal sources of individuals based on otolith near core chemical composition.

Short-term variability of fish condition and growth in estuarine and shallow coastal areas.

Short-term variability in condition factor: relative condition factor Kn; biochemical condition: RNA:DNA and protein content; and instantaneous growth rates were determined in estuarine and coastal fish. Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps were sampled in the Tejo estuary, while Trachurus trachurus was sampled in an adjacent shallow coastal area. Variation of condition indices was more frequent at the week scale (sampling periods with fortnight intervals) than at the daily scale (consecutive days in each sampling period) in all species.

Current limitations of global conservation to protect higher vulnerability and lower resilience fish species.

Estuaries are threatened by intense and continuously increasing human activities. Here we estimated the sensitivity of fish assemblages in a set of estuaries distributed worldwide (based on species vulnerability and resilience), and the exposure to cumulative stressors and coverage by protected areas in and around those estuaries (from marine, estuarine and freshwater ecosystems, due to their connectivity). Vulnerability and resilience of estuarine fish assemblages were not evenly distributed globally and were driven by environmental features.

Contrasting patterns of energy metabolism in northern vs southern peripheral European flounder populations exposed to temperature rising and hypoxia.

A two months common garden experiment was carried out to explore the potential differences of energy metabolism in northern core (France, 50°N and 47°N) vs southern peripheral (Portugal, 41°N) populations of European flounder Platichthys flesus, submitted to cold condition (CC: water temperature = 10 °C) and to warm and hypoxic condition (WHC: water temperature = 22 °C, and moderate hypoxia with O saturation = 40% during the last 6 days). Convergent growth rates (in length) were observed in the different populations and conditions, when the southern peripheral population of Portugal did not grow under cold conditions. A general reduction in liver lipid storage was observed in all populations subjected to WHC when compared to CC, whereas muscle lipid storage was unaffected.

Global patterns and predictors of fish species richness in estuaries.

1. Knowledge of global patterns of biodiversity and regulating variables is indispensable to develop predictive models. 2.

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: a stable isotope approach.

Stable carbon and nitrogen isotopes (δ¹³C, δ¹⁵N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among producers and consumers were identified. Stable isotope analysis was performed in different producers, primary consumers (main prey items for fish) and fish species (Solea solea, Solea senegalensis, Pomatoschistus microps, Dicentrarchus labrax, Liza ramada, Diplodus vulgaris and Atherina presbyter) of two areas in each estuary, in July and October 2009.

Selecting statistical models and variable combinations for optimal classification using otolith microchemistry.

Reliable assessment of fish origin is of critical importance for exploited species, since nursery areas must be identified and protected to maintain recruitment to the adult stock. During the last two decades, otolith chemical signatures (or "fingerprints") have been increasingly used as tools to discriminate between coastal habitats. However, correct assessment of fish origin from otolith fingerprints depends on various environmental and methodological parameters, including the choice of the statistical method used to assign fish to unknown origin.