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- Seagrass ecophysiological performance under ocean warming and acidificationPublication . Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana Rita; Rosa, Inês; F. Grilo, Tiago; Caçador, Isabel; Calado, Ricardo; Rosa, RuiSeagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.
- 3D chemoecology and chemotaxonomy of corals using fatty acid biomarkers: Latitude, longitude and depthPublication . Figueiredo, Cátia; Baptista, Miguel; Rosa, Inês; Lopes, Ana Rita; Dionísio, Gisela; Rocha, Rui J.M.; Cruz, Igor C.S.; Kikuchi, Ruy K.P.; Simões, Nuno; Leal, Miguel Costa; Tojeira, Inês; Bandarra, Narcisa; Calado, Ricardo; Rosa, RuiWith the objective of uncovering differences in the fatty acid (FA) composition of hexa- and octocorals from different climatic zones (equatorial, subtropical and tropical) and distinct habitats (e.g. rock and coral reefs; intertidal to deep-sea environments), the FA composition of 36 hexa- and octocoral species (132 specimens) was analysed (including the first characterization of organisms from the order Zoantharia and deep-sea gorgonians). PCA was applied in a FA matrix of the ten major PUFAs to detect differences among coral groups. Fatty acid profile analysis confirmed that C24 polyunsaturated FAs are suitable chemotaxonomic biomarkers to separate hexa- and octocorals. The polyunsaturated FA 22:6n-3 was identified as a useful biomarker to distinguish between zoantharians and scleractinians. Also, we discuss the role of food availability (type of phytoplankton assemblage) in relation to autotrophic carbon significance and in the establishment of FA profiles of octocorals from the West and East coasts of the Atlantic Ocean. Furthermore, we show that the occurrence of high levels of primary productivity hinder the use of FA profiles to distinguish between zooxanthellate and azooxanthellate octocorals. Finally, we present and discuss the particular traits of the FA profile of deep-sea gorgonians while comparing it with that of shallow species.
- “Gone with the wind”: Fatty acid biomarkers and chemotaxonomy of stranded pleustonic hydrozoans (Velella velella and Physalia physalis)Publication . Lopes, Ana Rita; Baptista, Miguel; Rosa, Inês; Dionísio, Gisela; Gomes-Pereira, José; Paula, José Ricardo; Figueiredo, Cátia; Bandarra, Narcisa; Calado, Ricardo; Rosa, RuiMarine pleustonic species such as the hydrozoans Velella velella and Physalia physalis, are known to drift in the world's oceans driven by winds, currents and tides. Here we present the first chemotaxonomic characterization, based on the fatty acid (FA) profile, of these two charismatic oceanic species that thrive in the interface layer between air and the water column in adult stages. Moreover, we compared their FA profiles with those from other representative cnidarian orders (Rhizostomeae, Anthomedusae, Siphonophorae, Alcyonacea, Scleractinia, Helioporacea and Pennatulacea). Velella velella and P. physalis mainly differed in the presence of symbiotic dinoflagellates markers (18:3n-6, 18:4n-3 and 20:5n-3 polyunsaturated FAs), present in higher percentage in the former, and bacterial markers (odd-numbered, branched and 18:1n-7 FAs), which were more representative in the latter. When comparing these species' FA profiles with the ones of other cnidarians orders, the presence/absence of endosymbionts and of specific FAs (tetracosapentaenoic and tetracosahexaenoic acids) as well as the latitudinal habitats were the main drivers for the distinction between groups.
- Nudibranchs out of water: long-term temporal variations in the abundance of two Dendrodoris species under emersionPublication . Cyrne, Ricardo; Rosa, Inês; Faleiro, Filipa; Dionísio, Gisela; Baptista, Miguel; Couto, Ana; Pola, Marta; Rosa, RuiThe sudden appearance and disappearance of nudibranchs in intertidal areas have puzzled researchers all over the world, giving rise to a great diversity of theories to explain it. Here we conducted a five-year survey to evaluate seasonal changes in the abundance of Dendrodoris herytra and D. grandiflora in the Sado estuary (Portugal) and to explore a possible relationship with environmental factors such as temperature, salinity, turbidity and dissolved oxygen. Moreover, we report, for the first time, the capacity of Dendrodoris nudibranchs to tolerate emersion (unhidden and completely exposed to sun exposure) during low tides. Our results showed that both species consistently started to appear emerged in March, reaching a peak abundance between April and May, and completely disappearing in July. In both species, this temporal trend was significantly associated with water temperature, turbidity, and dissolved oxygen, but not with salinity. We argue that the sudden appearance and disappearance of these nudibranchs in intertidal areas may result from a seasonal horizontal movement of adult nudibranchs from subtidal areas to mate in intertidal areas during spring, when phytoplankton production is enhanced and planktotrophic larvae may benefit from greater food availability.