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The Atlantic blue crab Callinectes sapidus Rathbun, 1896 is native in the western Atlantic, however it is a non-indigenous species across Europe since 1900, among other world regions. In this paper, we report the first occurrences of this species in the Ria Formosa lagoon and in the Guadiana estuary (SW-Iberian Peninsula, Europe) which occurred in 2016 and July 2017, respectively. We hypothesize that the introduction of this species into these ecosystems might be due to the expansion of the Guadalquivir estuary population through natural processes (larval advection, active movement), or due to unintended introduction events after being transported aboard fishing boats, or, less likely, through ballast water. Changes in Guadiana's river flow after the construction of the Alqueva dam might also explain the presence of another non-indigenous species in the Guadiana estuary. The hypotheses presented, regarding the introduction of the Atlantic blue crab into these ecosystems and of its co-occurrence with other decapod species, are framed in a broader context to serve as a future research framework. The use of the Atlantic blue crab as a new fishing resource is also proposed, namely if it is to be used exclusively by local communities and if no deleterious impacts upon other fisheries and the ecosystem occur from this new fishery. Agência financiadora / Número do projeto Delta Stewardship Council Delta Science Program 1167 Foundation for Science and Technology (FCT, Portugal) UID/Multi/04326/2013 European Regional Development Fund (COMPETE program-Operational Competitiveness Programme) FCT IF/00661/2014/CP1234 SFRH/BD/104209/2014 SFRH/BPD/108949/2015 Berkeley Research Impact Initiative (BRII) - UC Berkeley Library 16-01-04-FMP-0005 info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/publishedVersion

Temperate marine fish larvae use a series of environmental cues (e.g., olfactory, hearing, visual) to mediate the selection of nursery habitats. However, habitat selection may vary according to individuals' physiological condition. Therefore, this study aimed to determine the ability of gilthead seabream (Sparus aurata L., 1758) larvae to utilize natural odor cues to locate nursery habitats along ontogeny and to examine how it varies with individual's physiological condition. The hypothesis being tested is that S. aurata larvae prefer coastal rocky reefs as nursery areas, but they might use coastal lagoons as nursery grounds—ecosystems known for their productivity—if under starvation conditions, as a compensatory mechanism to avoid slow growth or even death. A choice-chamber experiment was used to investigate the behavioral responses of satiated and starved laboratory-reared S. aurata larvae, along ontogeny (pre-flexion, flexion, post-flexion), to water collected in a coastal artificial rocky reef and a coastal lagoon. The physiological condition of S. aurata larvae was determined by analyzing several biochemical condition indices. Complementarily, a new set of four preference indexes were developed—Choice-Chamber Preference Indexes—and discussed to provide a clear measure of the behavioral changes of a species along ontogeny by balancing all the behavioral choices made during the experimental trials, including the unresponsive behavior. A developmental threshold was identified at 24 days post-hatching, before which insufficient swimming capability disabled responsive behavior. Beyond this threshold, post-flexion larvae preferred rocky coastal water over lagoon water, even if under starvation conditions or poor physiological condition, despite the fact that the unresponsive behavior was largely predominant. S. aurata larvae displayed a cautionary behavioral strategy, so the compensatory mechanisms to ensure metapopulation stability and resilience have to rely on their feeding plasticity and on being a batch-spawning species (i.e., diversified bet-hedging strategy) to compensate the lack of apparent behavioral plasticity. info:eu-repo/semantics/publishedVersion

Climate change and the overall increase of seawater temperature are causing a poleward shift in species distribution, which includes a phenomenon described as the tropicalization of temperate regions. This work aims to report the first records of four species off the southwestern Iberian Peninsula, namely, the oceanic puffer Lagocephalus lagocephalus (Linnaeus, 1758), the Madeira rockfish Scorpaena maderensis Valenciennes, 1833, the ornate wrasse Thalassoma pavo (Linnaeus, 1758), and the bearded fireworm Hermodice carunculata (Pallas, 1766). These last three species, along with other occurrences of aquatic fauna and flora along the Portuguese coast, reveal an ongoing process of poleward expansion of several species, which urgently necessitates a comprehensive survey along the entire Iberian Peninsula. The putative origins of these subtropical and tropical species off continental Portugal are discussed, as well as the potential public health problems that two of the four reported species may cause. Agência financiadora Fundação para a Ciencia e a Tecnologia (FCT) SFRH/BD/140556/2018 SFRH/BD/104209/2014 Delta Stewardship Council 1167 Delta Science Program 1167 Fundação para a Ciencia e a Tecnologia (FCT) UID/Multi/04326/2013 European Regional Development Fund (COMPETE Program, Operational Competitiveness Program) info:eu-repo/semantics/publishedVersion