Distribuição de Patella candei gomesii d’Orbigny 1839 em diferentes tipologias de habitats naturais em S. Miguel, Açores

Tese de mestrado. Biologia (Ciências do Mar). Universidade de Lisboa, Faculdade de Ciências, 2013O intertidal é das áreas mais exploradas dos oceanos devido à sua fácil acessibilidade, diversidade ambiental, riqueza de organismos e facilidade de os observar. As condições ambientais variam de tal forma que os organismos intertidais possuem adaptações específicas para poderem viver nesse ambiente. Nos Açores, o intertidal é constituído por escarpas altas e ingremes, com praias de escoada, blocos e areia. De origem basáltica, é substrato para musgos algais, algas frondosas e crostosas e invertebrados como cracas, litorinas e lapas. P. candei gomesii é uma subespécie que só existe nos Açores e encontra-se no intertidal e no subtidal pouco profundo. Esta lapa é sujeita a uma exploração elevada podendo levar a extinção e consequentemente à dominância algal no intertidal açoriano. O objectivo do presente estudo é avaliar se existem diferenças na distribuição e no tamanho da lapa Patella candei em diferentes habitats naturais da zona intertidal (blocos e escoada lávica) da ilha de São Miguel. Procedeu-se à realização de quantificações e de medições dos organismos associados aos substratos, assim como à recolha de fotografias, posteriormente analisadas em laboratório, para a obtenção de percentagens de cobertura. Os resultados revelaram que a comunidade de ambos os habitats é dominada por musgo algal e rocha nua integrando formas crostosas, litorinas e cracas em menor abundância, com contribuições diferentes e que variam ao longo do tempo. A abundância e tamanho de P. candei variaram com o habitat, estando a menor abundância e os organismos de maior tamanho no habitat escoada.The intertidal is one of the most explored areas due to its easy access, environmental diversity and to the easily observed organisms’ richness. The environmental conditions vary a lot, therefore the organisms need specific adaptations to be able to live in such harsh conditions. The Azorean intertidal consists of high and steep cliffs with rocky platforms, cobble, boulder and few sand beaches. The basaltic substrate is covered by algal turf, canopy-forming and encrusting algae and invertebrates like barnacles, littorids and limpets. P. candei gomesii is an endemic Azorean limpet that can be found on subtidal and mid shore locations. The intense exploitation of this limpet can lead to its extinction and as a result in an algal dominance of the Azorean intertidal. The main aim of this study is to evaluate the differences in distribution and size of the limpet Patella candei in different natural habitats (boulders and rocky platforms) of the S. Miguel Island intertidal. Quantifications and measurements of organisms associated to the substrates were made, as well as the collection of photography’s, analyzed posteriorly in the laboratory, to obtain the cover percentage. In both habitats the community is mostly represented by the algal turf and bare rock with a lower abundance and isolated contributions of encrusting algae, littorids and barnacles that varied along the time. P. candei size and abundance varies with habitat, with the lower abundance and largest lengths rccorded on the rocky platforms locations

Demonstration of a transnational cooperation for harmonized chlorophyll a monitoring in the North East Atlantic Ocean

Comunicación presentada al EUROGOOS 2023, Galway, Ireland 3-5 October 2023The concentration of chlorophyll a (Chla), a proxy for phytoplankton biomass, is used as indicator for several criteria of three Marine Strategy Framework Directive (MSFD) descriptors (D1C6, the biodiversity of pelagic habitats; D4, food webs; and D5, eutrophication). Satellite Earth observation utilises algorithms that link the satellite observations of waterleaving radiance and the in-water Chla. Among the main sources of variability around this regression to define algorithms are the uncertainties in the in situ measurements due to the lack of consistency in the approaches employed in monitoring programs and research cruises. For example, global analyses based on measurements of Chla by high-performance liquid chromatography (HPLC), considered the reference technique for Chla, are usually derived from studies of independent investigators, so methodological differences between laboratories can introduce significant uncertainties. In addition, since HPLC is a relatively expensive and expertise-demanding technique, Chla concentration have been customarily determined in long-term oceanographic time-series programs by alternative techniques, such as spectrofluorometry (e.g., in RADIALES (Spain)) and fluorometry (e.g., in Plymouth Station L4, Western Channel Observatory (UK)). However, the agreement in the results obtained with these techniques has only been compared in a few ancient studies. The cooperation among Member States required by the MSFD for methodological harmonization has triggered a transnational collaboration involving some partners of the Interreg Atlantic Area project iFADO (Innovation in the framework of the Atlantic deep ocean) for a joint monitorization of Chla in the North East Atlantic Ocean (NEA) region. In situ data have been obtained in 21 research cruises and sampling sites, from coastal to offshore environments, by using standardized sampling and analytical methods. We will report on the results obtained from this operational demonstration and how this collaborative transnational initiative allowed us: i) to intercalibrate the methods currently used for the analysis of discrete samples (HPLC, spectrofluorometry, fluorometry) and assess them in terms of accuracy, costs and effectiveness; ii) to calibrate continuous measurements obtained with optical sensors and remote sensing results with HPLC data; iv) to extend in situ observations temporally and spatially through remote sensing for MSFD assessments; iii) to contribute to the integration of data of different accuracy, spatial scale and resolution in databases and to their dissemination in data hubs according to FAIR principles. This work will provide detailed guidelines for in situ sampling, analysis, and data quality control for Chla monitoring and will contribute harmonized data for the next MSFD assessment cycles for the target descriptors

Assessing phytoplankton community composition in the Atlantic Ocean from in situ and satellite observations

The Atlantic Meridional Transect (AMT) program (www.amt-uk.org) provides the perfect opportunity to observe the phytoplankton community size structure over a long latitudinal transect 50oN to 50oS, thereby covering the most important latitude-related basin-scale environmental gradients of the Atlantic Ocean. This work presents cell abundance data of phytoplankton taxa recently collected during cruises AMT28 and 29 (in 2018 and 2019, respectively) using flow cytometer and microscope observations, as well as the pigment composition of the community, to assess the abundance and spatial distribution of taxonomic groups across the Atlantic. The community size structure showed a clear consistency between cruises at large spatial scale, with a dominance of picoplanktonic Cyanobacteria in oceanic gyres, an increase in all groups in the equatorial upwelling region, and high biomass of microplankton size class at higher latitudes. Phytoplankton carbon biomass for oceanographic provinces, ranged from median values of 10 to 47 mg Carbon m-3, for the oligotrophic gyres, and South Atlantic (45°S-50oS), respectively. Satellite images of total chlorophyll a (as a proxy for phytoplankton biomass) as well as the relative contribution of the three phytoplankton size classes were produced for both cruises, and despite the small number of matchups, statistically agreed well with in situ size classes estimated as carbon biomass, constituting the first attempt in the literature to match satellite size classes with in situ data derived from cell abundance. The comparison of community structure between recent cruises (2019, 2018, 2015) and earlier ones (1995-1998) indicates a decrease in the number of diatom-bloom forming species, and an increase in Dinoflagellates, whereas nitrogen-fixing Trichodesmium abundance in tropical Atlantic remains constant. Within the recent period, a relative increase in the median values of picoplankton fraction was seen in SATL region, counterbalanced by a decrease in both nano- and microplankton fractions. Additionally, this study includes a database of species identified by microscopy, which had been interrupted for 20 years, providing a basis for long-term series of phytoplankton species

Response of coccolithophore communities to oceanographic and atmospheric processes across the North- and Equatorial Atlantic

Changes in coccolithophore productivity in response to climate-driven ocean warming are likely to have cascading biogeochemical effects that feed back to the changing climate. This paper investigates the role (and interplay) of large-scale oceanographic and atmospheric processes across the North- and Equatorial Atlantic, including Saharan dust deposition, on the distribution of coccolithophore communities. The study is based on biological and hydrological data collected across the photic zone of the ocean, and aerosol data collected from the lower atmosphere, across 50°N–1°S during the Atlantic Meridional Transect in boreal Autumn of 2018 (AMT28), in synergy with Earth Observations. Results confirm existing understanding of the distribution of coccolithophore communities which are related to major meridional hydrological gradients across the North Atlantic. Dynamic, oxygenated and microphytoplankton-enriched waters at higher-latitudes were characterized by less diverse coccolithophore populations, dominated by placolith-bearing r-selected coccolithophores. In contrast, the heavily stratified and picoplankton-enriched waters of the subtropical gyre revealed more diverse populations, dominated by umbelliform coccolithophores and holococcolithophores at the surface, and by floriform taxa in the lower photic zone. Mean concentrations of 14.4×103 cells/L present in the North Atlantic Tropical Gyre Province (30–12°N), only slightly lower compared to 17.7×103 cells/L produced in the North Atlantic Drift province (50–40°N), provide a snapshot perspective on the importance of coccolithophore production in heavily stratified gyre conditions. Higher concentrations of 19’-Hexanoyloxyfucoxanthin (HexFuco) in regions of enhanced production of r-selected placolith-bearing species suggest that this pigment should not be generalized as a proxy for the entire coccolithophore community. Enhanced abundances of fast-blooming Emiliania huxleyi and Gephyrocapsa oceanica, and of cyanobacteria (including both picoplankton and N2-fixing Trichodesmium spp.) at the surface of the region of more persistent Saharan dust deposition (at ~12-10°N) appeared to result from dust-born nutrient input. Underneath this stratified surface layer, enhanced productivity in the deep chlorophyll maximum (DCM) appeared decoupled from that on the surface, fueled by geostrophic eastward shoaling of the nutricline across the tropical North Atlantic. As this was the region of highest macronutrient concentrations measured along and below the nutricline, our data suggest that the NE tropical Atlantic may act as a permanent dust-born nutrient depocenter as previously hypothesized

A compilation of global bio-optical in situ data for ocean colour satellite applications – version three

A global in situ data set for validation of ocean colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, starting in 1997, now extends to 2021, which is important for the validation of the most recent satellite optical sensors such as Sentinel 3B OLCI and NOAA-20 VIIRS. The data set comprises in situ observations of the following variables: spectral remote-sensing reflectance, concentration of chlorophyll-a, spectral inherent optical properties, spectral diffuse attenuation coefficient, and total suspended matter. Data were obtained from multi-project archives acquired via open internet services or from individual projects acquired directly from data providers. Methodologies were implemented for homogenization, quality control, and merging of all data. Minimal changes were made on the original data, other than conversion to a standard format, elimination of some points, after quality control and averaging of observations that were close in time and space. The result is a merged table available in text format. Overall, the size of the data set grew with 148 432 rows, with each row representing a unique station in space and time (cf. 136 250 rows in previous version; Valente et al., 2019). Observations of remote-sensing reflectance increased to 68 641 (cf. 59 781 in previous version; Valente et al., 2019). There was also a near tenfold increase in chlorophyll data since 2016. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented and it is also possible to analyse each set of data separately. The compiled data are available at https://doi.org/10.1594/PANGAEA.941318 (Valente et al., 2022)

Response of coccolithophore communities to oceanographic and atmospheric processes across the North- and Equatorial Atlantic

Changes in coccolithophore productivity in response to climate-driven ocean warming are likely to have cascading biogeochemical effects that feed back to the changing climate. This paper investigates the role (and interplay) of large-scale oceanographic and atmospheric processes across the North- and Equatorial Atlantic, including Saharan dust deposition, on the distribution of coccolithophore communities. The study is based on biological and hydrological data collected across the photic zone of the ocean, and aerosol data collected from the lower atmosphere, across 50°N–1°S during the Atlantic Meridional Transect in boreal Autumn of 2018 (AMT28), in synergy with Earth Observations. Results confirm existing understanding of the distribution of coccolithophore communities which are related to major meridional hydrological gradients across the North Atlantic. Dynamic, oxygenated and microphytoplankton-enriched waters at higher-latitudes were characterized by less diverse coccolithophore populations, dominated by placolith-bearing r-selected coccolithophores. In contrast, the heavily stratified and picoplankton-enriched waters of the subtropical gyre revealed more diverse populations, dominated by umbelliform coccolithophores and holococcolithophores at the surface, and by floriform taxa in the lower photic zone. Mean concentrations of 14.4×103 cells/L present in the North Atlantic Tropical Gyre Province (30–12°N), only slightly lower compared to 17.7×103 cells/L produced in the North Atlantic Drift province (50–40°N), provide a snapshot perspective on the importance of coccolithophore production in heavily stratified gyre conditions. Higher concentrations of 19’-Hexanoyloxyfucoxanthin (HexFuco) in regions of enhanced production of r-selected placolith-bearing species suggest that this pigment should not be generalized as a proxy for the entire coccolithophore community. Enhanced abundances of fast-blooming Emiliania huxleyi and Gephyrocapsa oceanica, and of cyanobacteria (including both picoplankton and N2-fixing Trichodesmium spp.) at the surface of the region of more persistent Saharan dust deposition (at ~12-10°N) appeared to result from dust-born nutrient input. Underneath this stratified surface layer, enhanced productivity in the deep chlorophyll maximum (DCM) appeared decoupled from that on the surface, fueled by geostrophic eastward shoaling of the nutricline across the tropical North Atlantic. As this was the region of highest macronutrient concentrations measured along and below the nutricline, our data suggest that the NE tropical Atlantic may act as a permanent dust-born nutrient depocenter as previously hypothesized

Phytoplankton pigment concentrations and phytoplankton groups measured on water samples collected from various expeditions in the Atlantic Ocean from 71°S to 84°N

This data set composes a large amount of quality controlled in situ measurements of major pigments based on HPLC collected from various expeditions across the Atlantic Ocean spanning from 71°S to 84°N, including ten expeditions with RV Polarstern from the North Atlantic to the Arctic Fram Strait: PS74, PSS76, PS78, PS80, PS85, PS93 (https://doi.org/10.1594/PANGAEA.894875), PS99 (https://doi.org/10.1594/PANGAEA.894875), PS106 (https://doi.org/10.1594/PANGAEA.899284), PS107 (https://doi.org/10.1594/PANGAEA.894875), PS121 (https://doi.org/10.1594/PANGAEA.941011), and four expeditions (two with RV Polarstern and two Atlantic Meridional Transect expeditions with RRS James Clark Ross and RRS Discovery) in the trans-Atlantic Ocean: PS113 (https://doi.org/10.1594/PANGAEA.913536), PS120, AMT28 and AMT29. Chlorophyll a concentration (Chl-a) of six phytoplankton functions groups (PFTs) derived from these pigments have been also included. This published data set has contributed to validate satellite PFT products available on the EU funded Copernicus Marine Service (CMEMS, https://marine.copernicus.eu/), which are derived from multi-sensor ocean colour reflectance data and sea surface temperature using an empirical orthogonal function based approach (Xi et al. 2020; 2021). Description on in situ PFT Chl-a determination from pigment data: PFT Chl-a in this data set were derived using an updated diagnostic pigment analysis (DPA) method (Soppa et al., 2014; Losa et al., 2017) with retuned coefficients by Alvarado et al (2021), that was originally developed by Vidussi et al. (2001), adapted in Uitz et al. (2006) and further refined by Hirata et al. (2011) and Brewin et al. (2015). The values of retuned DPA weighting coefficients for PFT Chl-a determination are: 1.56 for fucoxanthin, 1.53 for peridinin, 0.89 for 19'-hexanoyloxyfucoxanthin, 0.44 for 19'-hexanoyloxyfucoxanthin, 1.94 for alloxanthin, 2.63 for total chlorophyll b, and 0.99 for zeaxanthin. The coefficient retuning was based on an updated global HPLC pigment data base for the open ocean (water depth >200 m), which was compiled based on the previously published data sets spanning from 1988 to 2012 described in Losa et al. (2017), with updates in Xi et al. (2021) and Álvarez et al. (2022), by adding other newly available HPLC pigment data collected between 2012 and 2018 on SeaBASS (https://seabass.gsfc.nasa.gov/), PANGAEA, British Oceanographic Data Centre (BODC, https://www.bodc.ac.uk/), and Australian Open Access to Ocean Data (AODN, https://portal.aodn.org.au/) (as of February 2020)