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Fisheries bycatch is a critical threat to sea turtle populations worldwide, particularly because turtles are vulnerable to multiple gear types. The Canary Current is an intensely fished region, yet there has been no demographic assessment integrating bycatch and population management information of the globally significant Cabo Verde loggerhead turtle (Caretta caretta) population. Using Boa Vista island (Eastern Cabo Verde) subpopulation data from capture–recapture and nest monitoring (2013–2019), we evaluated population viability and estimated regional bycatch rates (2016–2020) in longline, trawl, purse‐seine, and artisanal fisheries. We further evaluated current nesting trends in the context of bycatch estimates, existing hatchery conservation measures, and environmental (net primary productivity) variability in turtle foraging grounds. We projected that current bycatch mortality rates would lead to the near extinction of the Boa Vista subpopulation. Bycatch reduction in longline fisheries and all fisheries combined would increase finite population growth rate by 1.76% and 1.95%, respectively. Hatchery conservation increased hatchling production and reduced extinction risk, but alone it could not achieve population growth. Short‐term increases in nest counts (2013–2021), putatively driven by temporary increases in net primary productivity, may be masking ongoing long‐term population declines. When fecundity was linked to net primary productivity, our hindcast models simultaneously predicted these opposing long‐term and short‐term trends. Consequently, our results showed conservation management must diversify from land‐based management. The masking effect we found has broad‐reaching implications for monitoring sea turtle populations worldwide, demonstrating the importance of directly estimating adult survival and that nest counts might inadequately reflect underlying population trends. [ABSTRACT FROM AUTHOR]

The Sahara desert is a major global source of dust that is mostly transported southwest over the ocean off West Africa. The presence of this dust impacts the remote sensing of ocean surface properties. These aerosols have absorbing properties that are poorly accounted for in the standard ocean color data processing algorithm. This can result in an overestimation of the atmospheric contribution to the ocean color signal and consequently an underestimation of the oceanic contribution. A two-step algorithm initially applied to the Sea-viewing Wide field-of-view Sensor (SeaWiFS) data was adapted to the Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) sensor in the Northwest African region. The Northwest African region is a very productive region, where pelagic resources are an important socio-economic sector. Improving atmospheric correction of ocean color products is, thus, of particular interest for this oceanic region. The two-step approach of classifying the top-of-atmosphere radiance spectra for a better estimate of aerosol type on the one hand, and using an optimization method to fit the parameters of these aerosols and chlorophyll-a concentration (Chla) on the other hand, allows for a better representation of the optical thickness, a correction of the marine reflectance spectrum, and an increase in the spatio-temporal coverage of the area. To the extent that the properties of the water color signal are improved by this data processing, the Chla estimates should also be improved by this approach. However, it is difficult to conclude on this point from the available in situ observations. [ABSTRACT FROM AUTHOR]

For the first time, four dedicated hydrographic cruises—one in each season—took place in 2015 around the Canary Islands to determine the seasonality of the flows at the eastern boundary of the North Atlantic Subtropical Gyre. The Canary Current (CC) is the eastern boundary current of the North Atlantic Subtropical Gyre and links the Azores Current with the North Equatorial Current. The 2015 estimations show that the CC has a seasonal behavior in its path and strength, flowing on its easternmost position in winter (3.4 ± 0.3 Sv), through the Canary Islands in spring (2.1 ± 0.7 Sv) and summer (2.0 ± 0.6 Sv) and on its westernmost position in fall (3.2 ± 0.4 Sv). At the Lanzarote Passage (LP), the dominant flow is southward except in fall, where a northward transport is observed at the surface (1.1 ± 0.3 Sv) and intermediate (1.3 ± 0.2 Sv) layers. Combining all the available transport estimations, a historical composite observational seasonal cycle is constructed which fits the 2015 seasonal cycle. Hence, a solid seasonal cycle is constructed supported by all the available observations in the area. The LP seasonal cycle and its seasonal amplitude match the seasonal cycle and amplitude of the Atlantic Meridional Overturning Circulation (AMOC) measured by the RAPID‐MOCHA data array. These results indicate that the seasonal cycle of the AMOC of the RAPID‐MOCHA data array is driven by the dynamics of the eastern boundary current system. Plain Language Summary: In this study, we explore for the first time the seasonal cycle of the main ocean currents existing at the eastern side of the North Atlantic Subtropical Gyre using data from four cruises that took place in each season in 2015. The Canary Current (CC) is the southward flow that connects the Azores Current with the North Equatorial Current. The 2015 estimations show that CC shifts westward from winter to fall. In addition, it also changes transport seasonally being the weakest in spring and summer, and the strongest in fall. The Lanzarote Passage (LP) is the geographical area between Lanzarote and Africa, it is considered to be the eastern end of the North Atlantic Subtropical Gyre. Through the LP the flow is mainly southward except in fall when the flow reverses. A composite seasonal cycle arises from combining all the available observations with the outputs of this study. The LP seasonal amplitude and cycle match the ones of the Atlantic Meridional Overturning Circulation (AMOC) measured by the RAPID‐MOCHA data array. These results indicate that this seasonal cycle of the AMOC is driven by the dynamics of the eastern boundary currents. Key Points: The Canary Current varies its path and strength seasonally, moving westward from winter to fall and being the strongest in fallAt the Lanzarote Passage (LP), the flow is southward throughout the year except in fall when it reverses at the surface and intermediate layersThe LP seasonal cycle and its amplitude correlate with the seasonal cycle of the Atlantic Meridional Overturning Circulation as measured by the RAPID‐MOCHA array [ABSTRACT FROM AUTHOR]

The exact number of cetacean species present in Mauritanian waters is unknown. A first overview was published only in 1980, the latest in 1998. Yet, published information remains modest compared to, e.g., neighboring Senegal (first review in 1947). The complex oceanography of Mauritanian waters permits a mixed assemblage of cetacean fauna, with the distribution of both cool temperate and (sub)tropical species. In this review, we use our own observations from strandings, bycatches and vessel-based surveys, as well as published and grey literature, to support an updated inventory of cetaceans of Mauritania. This checklist includes two new authenticated species records: Kogia sima (Owen) (Kogiidae) and Lagenodelphis hosei Fraser (Delphinidae). Stenella coeruleoalba (Meyen) (Delphinidae) is verifiably documented for the first time. Further, a first specimen record of Stenella longirostris (Gray) (Delphinidae) is described, as well as second specimen records of Mesoplodon europaeus (Gervais) (Ziphiidae), Steno bredanensis (G. Cuvier) (Delphinidae) and Megaptera novaeangliae (Borowski) (Balaenopteridae). Of 30 reported species, 27 (of six families) are fully supported, while three species lack (accessible) voucher material though probably (P) occur in Mauritania: Balaenopteridae: Megaptera novaeangliae, Balaenoptera musculus (Linnaeus), B. borealis Lesson, B. omurai Wada, Oishi and Yamada, B. acutorostrata Lacépède, B. physalus (Linnaeus) and B. brydei Olsen (P); Physeteridae: Physeter macrocephalus Linnaeus; Kogiidae: Kogia sima (Owen) and K. breviceps (de Blainville); Delphinidae: Sousa teuszii (Kükenthal), Tursiops truncatus (Montague), Delphinus delphis Linnaeus, Stenella frontalis (G. Cuvier), Stenella attenuata (Gray), Stenella coeruleoalba (Meyen), Stenella longirostris (Gray), Stenella clymene (Gray), Steno bredanensis (G. Cuvier), Peponocephala electra (Gray) (P), Lagenodelphis hosei (Fraser), Grampus griseus (G. Cuvier), Globicephala macrorhynchus Gray, Globicephala melas (Traill) (P), Orcinus orca (Linnaeus) and Pseudorca crassidens (Owen); Ziphiidae: Ziphius cavirostris G. Cuvier, Mesoplodon europaeus and Mesoplodon densirostris (de Blainville); Phocoenidae: Phocoena phocoena (Linnaeus). Finally, we report the first case for continental northwest Africa of tattoo skin disease in a stranded D. delphis. [ABSTRACT FROM AUTHOR]

Understanding seasonal and multiyear variability of primary producers’ populations in the Mauritanian coastal upwelling system along the northwestern African margin may help to predict future impact of climate change (e.g., nutrient availability, productivity, and phyto- and zooplankton dynamics). For this, continuous, long time-series are required. A major challenge in obtaining these time-series is the logistics associated with the uninterrupted, in-situ sampling over several years. Sediment traps represent a reliable alternative. In this study, we assess the variations of the diatom community in samples almost continuously collected between June 2003 and March 2020 with 17 sediment traps deployed at site CBeu (=Cape Blanc eutrophic), located at c. 20°N-18°45’W, offshore Mauritania in the Canary Current Eastern Boundary Upwelling Ecosystems (CC-EBUE). In addition to describing the multiyear dynamics of the total diatom flux and major shifts in the species-specific composition of the populations, our study addresses questions such as (i) how constant is the intrannual pattern of populations’ occurrence, (ii) what the amplitude of annual changes is, and (iii) how populations’ shifts relate to physical setting dynamics. Matching the occurrence of most intense seasonal upwelling, highest diatom flux maxima mainly occur in spring and summer between 2003 and 2020. The diverse diatom community (e.g., benthic, coastal upwelling, coastal planktonic, and open-ocean diatoms) closely follows the annual cycle of atmospheric and hydrologic conditions. Benthic diatoms dominate during spring and summer (e.g., upwelling season), while open-ocean diatoms contribute the most in fall and winter when the upper water column stratifies. As no persistent –either decreasing or increasing trend of diatom productivity over the 17 sampled years, our results are at odds with Bakun’s hypothesis of upwelling intensification. Anchoring temporal changes of diatoms in a wider environmental frame allows for insights into the complex dynamics of the Mauritanian upwelling ecosystem and the populations’ response to climate forcing. This helps in establishing the scientific basis for modeling future states of the CC-EBUE and/or comparable environments.

The Sahara desert is a major global source of dust that is mostly transported southwest over the ocean off West Africa. The presence of this dust impacts the remote sensing of ocean surface properties. These aerosols have absorbing properties that are poorly accounted for in the standard ocean color data processing algorithm. This can result in an overestimation of the atmospheric contribution to the ocean color signal and consequently an underestimation of the oceanic contribution. A two-step algorithm initially applied to the Sea-viewing Wide field-of-view Sensor (SeaWiFS) data was adapted to the Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) sensor in the Northwest African region. The Northwest African region is a very productive region, where pelagic resources are an important socio-economic sector. Improving atmospheric correction of ocean color products is, thus, of particular interest for this oceanic region. The two-step approach of classifying the top-of-atmosphere radiance spectra for a better estimate of aerosol type on the one hand, and using an optimization method to fit the parameters of these aerosols and chlorophyll-a concentration (Chla) on the other hand, allows for a better representation of the optical thickness, a correction of the marine reflectance spectrum, and an increase in the spatio-temporal coverage of the area. To the extent that the properties of the water color signal are improved by this data processing, the Chla estimates should also be improved by this approach. However, it is difficult to conclude on this point from the available in situ observations.

The Canary current upwelling is one of the major eastern boundary coastal upwelling systems in the world, bearing a high productive ecosystem and commercially important fisheries. The Canary current upwelling system (CCUS) has a large latitudinal extension, usually divided into upwelling zones with different characteristics. Eddies, filaments and other mesoscale processes are known to have an impact in the upwelling productivity, thus for a proper representation of the CCUS and high horizontal resolution are required. Here we assess the CCUS present climate in the atmosphere–ocean regionally coupled model. The regional coupled model presents a global oceanic component with increased horizontal resolution along the northwestern African coast, and its performance over the CCUS is assessed against relevant reanalysis data sets and compared with an ensemble of global climate models (GCMs) and an ensemble of atmosphere-only regional climate models (RCMs) in order to assess the role of the horizontal resolution. The coupled system reproduces the larger scale pattern of the CCUS and its latitudinal and seasonal variability over the coastal band, improving the GCMs outputs. Moreover, it shows a performance comparable to the ensemble of RCMs in representing the coastal wind stress and near-surface air temperature fields, showing the impact of the higher resolution and coupling for CCUS climate modelling. The model is able of properly reproducing mesoscale structures, being able to simulate the upwelling filaments events off Cape Ghir, which are not well represented in most of GCMs. Our results stress the ability of the regionally coupled model to reproduce the larger scale as well as mesoscale processes over the CCUS, opening the possibility to evaluate the climate change signal there with increased confidence. [ABSTRACT FROM AUTHOR]

A 50‐year‐long (1958–2008) historical simulation of a climate‐to‐fish ecosystem model for anchovy (Eugralis encrasicolus) and sardine (Sardina pilchardus) populations in the upwelling ecosystem off NW Africa is revisited and analyzed. Anchovy and sardine annual adult abundances were correlated at interannual and decadal time scales in the historical run. A three‐step analysis method applied unraveled the environmental and life stage‐specific drivers underlying the bottom‐up mechanisms responsible for the simulated variability in anchovy and sardine populations. Changes in anchovy adult abundance were primarily controlled by larval survival, prey availability, and local upwelling strength, whereas sardine adult abundance was controlled by age‐1 growth affecting age‐2 fecundity and egg production via prey availability. Despite different diet preferences, the common sensitivity of anchovy and sardine to prey availability had a synchronizing effect on the two populations, with both anchovy and sardine doing better during years of higher plankton biomass and colder ocean temperatures. Analysis of potential links with modes of climate variability showed that anchovy dynamics were more tightly connected to the AMO while sardine dynamics were correlated to the NAO. This difference stemmed from the vulnerability of the anchovy population to enhanced coastal upwelling causing increased larval drift mortality. Finally, based on an earlier, similar modeling study for the Californian anchovy and Pacific sardine, we argue that the relatively warmer habitat off NW Africa compared to the coastal region off central California is a key feature explaining synchronous populations in the Canary Current versus out‐of‐phase anchovy and sardine cycles in the California Current. [ABSTRACT FROM AUTHOR]

Hurricane Michael formed on October 7, 2018, in the Northwestern Caribbean Sea, and quickly traveled northward through the Gulf of Mexico, making landfall on the Florida panhandle as a devastating Category 5 hurricane only 3 days later. Before landfall, Michael underwent rapid intensification, despite unfavorable atmospheric conditions. Using observations, we characterized the key ocean features encountered by Michael along its track, which are known for favoring hurricane intensification: high sea surface temperatures, upper ocean heat content and low salinity barrier layer conditions. Ocean observations were consistent with suppressed hurricane‐induced upper ocean cooling, which could only be observed by underwater gliders, and showed that Hurricane Michael constantly experienced sea surface temperatures above 28°C. We carried out ocean Observing System Experiments, which demonstrate that the combined assimilation of in situ and satellite ocean observations into a numerical ocean model led to the most realistic representation of the ocean conditions. They also suggest that, when using the Cooper‐Haines (1996) method to assimilate altimetry observations, assimilating temperature observations is necessary to constrain the model upper ocean vertical structure. We also performed coupled hurricane‐ocean simulations to assess the impact of ocean initial conditions on forecasting Michael. These simulations demonstrate that the ocean conditions, in particular the high sea surface temperatures north of 24°N, played a crucial role in the intensification of Michael. Coupled simulations initialized with the most realistic ocean conditions, constrained by field and satellite observations, show a ∼56% error reduction in wind intensity prior to landfall compared to simulations initialized without data assimilation. Plain Language Summary: Hurricane Michael formed on October 7, 2018, in the Northwestern Caribbean Sea, and quickly traveled northward through the Gulf of Mexico, making landfall on the Florida panhandle as a Category 5 hurricane only 3 days later. Michael intensified during most of its lifetime, despite undergoing unfavorable atmospheric conditions. We characterized the key ocean features under Hurricane Michael, which are known for favoring hurricane intensification: High sea surface temperatures and high heat content in the Loop Current and associated eddies, and in brackish surface waters from the Mississippi River plume that prevent mixing with colder waters below, as observed by ocean gliders. We then performed numerical experiments that demonstrate that the integration of satellite and in situ observations into the ocean model led to achieving the most realistic representation of the ocean. Last, we performed coupled hurricane‐ocean simulations that showed that the upper ocean conditions, especially the high sea surface temperatures in the northeastern Gulf, were essential to the intensification of Michael. These sensitivity experiments showed the importance of ocean observations to improve real‐time analyses of ocean conditions, and thus to improve operational models that provide guidance to hurricane forecasters, allowing them to better warn the public. Key Points: Observations reveal ocean features that favored the intensification of Michael: high temperature, high heat content, and barrier layerHurricane‐ocean simulations show that the ocean conditions supported hurricane intensification despite unfavorable atmospheric conditionsThe assimilation of satellite and in situ ocean observations led to 56% error reduction in wind intensity forecast prior to Michael landfall [ABSTRACT FROM AUTHOR]

In this study, we make use of historical wind direction observations to assemble an instrumental upwelling index (DUI) at the southern end of the Canary Current Upwelling System. The DUI covers the period between 1825 and 2014 and, unlike other upwelling indices, it does not rely neither in wind speed nor in reanalyzed data. In this sense, the DUI can be regarded as an instrumental index. Additionally, it avoids the suspected bias toward increasing wind speed of historical wind observations documented in previous research. Our results indicate that the frequency of the alongshore winds at the west coast of Africa between 10°N and 20°N measured by the DUI is significantly related with the wind stress and therefore the upwelling intensity in this region. The DUI presents a significant variability both at interannual and decadal timescales. We have not found any significant trend for the 20th century. However, when the entire length of the series is considered, a large shift toward more frequent alongshore winds is evidenced as a result of several decade‐long fluctuations which took place between the late 19th century and the beginning of the 20th century. This fact would imply that a significant change in the upwelling intensity at the southern end of the Canary Current Upwelling System should have occurred at the turn of the 20th century. Plain Language Summary: Along the coasts of Northwestern Africa, friction of the predominant winds results in an upward motion of sea water from intermediate depths toward the ocean surface. This phenomenon is known as "coastal upwelling" and it has a huge economic and social relevance. Cold upwelled water is rich in nutrients and yields very productive marine ecosystems. Therefore, knowing the changes of the upwelling intensity is of great importance. Unfortunately, prior to the 1950s, the scarcity of wind observations along these coasts difficulties the estimation of the coastal upwelling intensity, making the climatic history of this system uncertain. Since the late 18th century, a lot of ships have circumnavigated the African continent. Most of them took observations of wind direction that have come to the present day in form of records preserved in the ships' logbooks. In this study, we make use of these historical observations to calculate the intensity of the coastal upwelling. We have found that coastal upwelling in Northwest Africa is highly variable at decadal scale and we provide a strong evidence of a large change in the upwelling intensity that occurred around 1900. Key Points: Historical wind observations can be used to calculate the upwelling intensity at the Senegal‐Mauritanian coasts since the mid‐19th centuryWinds over the Senegal‐Mauritania coast may have experienced a shift around the year 1900 [ABSTRACT FROM AUTHOR]

For migratory seabirds, staging and wintering areas may be important targets for conservation. Declines of Roseate Tern Sterna dougallii populations have led to conservation initiatives at breeding sites on both sides of the North Atlantic. However, these could be compromised by environmental conditions in non‐breeding areas. The migratory ecology of Roseate Terns is poorly known and we used light‐level biologgers (geolocators) to identify the migratory routes, staging and wintering areas of Roseate Terns from two European colonies. Most birds wintered off the Ghanaian coast in the Gulf of Guinea, but some wintered further west off Sierra Leone and Liberia, or changed locations during the winter. In these areas, cold‐water upwellings of the Guinea Current Large Marine Ecosystem (GCLME) may provide vital foraging resources. Geolocations in combination with temperature measurements and satellite sea‐surface temperature data show that cold‐water upwellings of the Canary Current Large Marine Ecosystem (CCLME) were important areas for migratory staging, particularly on the return migration which was slower than the outward journey. These results emphasize the importance of productive cold‐water upwellings in the migratory ecology of Roseate Terns. The GCLME and CCLME are under threat from over‐exploitation, pollution and climate change; effective conservation of these environments will be important to secure the long‐term future of these and other seabirds. [ABSTRACT FROM AUTHOR]

Eastern Boundary Upwelling Ecosystems (EBUEs) are associated with high biological productivity, high fish catch and they highly contribute to marine carbon sequestration. Whether coastal upwelling has intensified or weakened under climate change in the past decades is controversially discussed and different approaches (e.g., time-series of chlorophyll, wind, sea surface temperature, modeling experiments) have been considered. We present a record of almost two decades of particle fluxes (1991–2009) from ca. 600 to 3100 m water depth in the Canary Basin at site ESTOC (European Station for Time series in the Ocean Canary Islands; ca. 29°N, 15°30.W, ca. 3600 m water depth), located in the offshore transition zone of the northern Canary Current-EBUE. We compare these flux records with those measured at a mesotrophic sediment trap site further south off Cape Blanc (Mauritania, ca. 21°N). The deep ocean fluxes at ESTOC in ca. 3 km recorded the evolution of the coastal Cape Ghir filament (30–32°N, 10–12°W) due to lateral advection of particles, whereas the upper water column sediment traps in ca. 1 km reflected the oligotrophic conditions in the overlying waters of ESTOC. We observed an increased emphasis in spring-time fluxes since 2005, associated with a change in particle composition, while satellite chlorophyll biomass did not show this pattern. Due to its northern location in the CC-EBUEs, spring biogenic fluxes at ESTOC provide a better relationship to the forcing of the North Atlantic Oscillation than those recorded further south off Cape Blanc. Off Cape Blanc, deep fluxes showed the best overlap with the deep ESTOC fluxes during the spring season before 2005. On the long-term, both chlorophyll and particle fluxes showed an increasing trend at ESTOC which was not observed further south at the mesotrophic Cape Blanc site. This might indicate that, depending on their location along the NW African margin, coastal upwelling systems react differently to global change.

Upwelling in eastern boundary current regions is crucial to bringing nutrient‐rich water to the photic zone and supporting the associated ecosystems. This upwelling is a result of the wind‐driven ocean circulation and is therefore susceptible to changes in the atmospheric circulation. We use the Community Earth System Model and observational data to explore the response of upwelling in the California Current and Canary Current systems to shifts in the Northern Hemisphere subtropical high‐pressure systems. We find that shifts in the North Pacific subtropical high explain a substantial fraction of both the short‐term variability and projected trend in upwelling in the California Current system during boreal summer. By contrast, the Canary Current system is less affected by shifts of the North Atlantic subtropical high, mostly because the strongest wind anomalies associated with shifts of this high‐pressure system occur too far north. We also find little impact from the Northern Hemisphere Hadley cell. Key Points: North Pacific subtropical high shifts explain much of the modeled trend in California Current system upwelling during boreal summerShifts of the North Atlantic subtropical high have only modest impacts on the Canary Current systemBoth eastern boundary current systems are relatively insensitive to changes in the Northern Hemisphere Hadley cell [ABSTRACT FROM AUTHOR]

Four hydrographic cruises carried out between ~26.5 and 31°N in the eastern North Atlantic Subtropical Gyre in fall (2016 and 2017) and spring (2017 and 2018) are used to identify water masses and infer oceanic circulation. Geostrophic velocities are initially adjusted by referencing them to data from a Lower Acoustic Doppler Current Profiler (LADCP) and later to velocities estimated with an inverse box model. The distribution of the intermediate water masses (700 to 1,400 m depth) varies seasonally. Antarctic Intermediate Water (AAIW) comprises the largest contributor to the seasonal cycle in the intermediate water masses. Circulation of the Canary Current (CC) differs in fall and spring. In fall, the CC flows southward through the western islands and recirculates south of the archipelago, subsequently flowing northward through the passage between the eastern islands and Africa. North of Lanzarote, the recirculated CC intensified as it is joined by a southeasterly branch of the CC north of Lanzarote. In spring, the net transport of the CC is southward. High interannual variability in mass transport is evident in both spring and fall as a result of the position of the current, with its easternmost (westernmost) position found in spring (fall) 2018 (2016). At intermediate levels, highly variable northward/southward transport is apparent in fall over the African slope, with the Intermediate Poleward Under Current (IPUC) only present in 2017. Plain Language Summary: The Canary Current is part of the eastern boundary of the North Atlantic Subtropical Gyre as well as the upwelling system off NorthWest Africa. Its location plays a major role in the Atlantic Meridional Overturning Circulation, which controls the global climate. Therefore, we have studied the Canary Current. Its circulation pattern and its seasonal and interannual variability have been inferred using data from four hydrographic cruises (two carried out in fall and two in spring) around the region of the Canary Islands. From these cruises we have computed the mass transport of the current and identified the water masses present on it. The results show a high seasonal variation in the intermediate water masses (those on the depth range from ~700 to 1,400 m depth). The mass transport of the current also shows a seasonal variability at surface levels (<700 m depth) and at intermediate levels. The current flows southward through the islands and the passage between the islands and Africa in spring, but in fall, the CC reverses south of Fuerteventura and flows northward through the passage between the archipelago and Africa. Interannually, the mass transport also presents differences, being higher in fall 2017 and spring 2018. Key Points: High seasonal and interannual variabilities of the Canary Current transport over the African slopeInterannual variability of the Intermediate Poleward UnderCurrentHigh interannual variability in the seasonal cycle of the Atlantic Meridional overturning Circulation in the eastern boundary [ABSTRACT FROM AUTHOR]

Long‐term data characterizing the oceans' biological carbon pump are essential for understanding impacts of climate variability on marine ecosystems. The "Bakun upwelling intensification hypothesis" suggests intensified coastal upwelling due to a greater land‐sea temperature gradient influenced by global warming. We present long time series of bathypelagic (approximately 1,200–3,600 m) particle fluxes from a coastal (CBeu: 2003–2016) and an offshore (CBmeso: 1988–2016) sediment trap setting located in the Canary Current upwelling. Organic carbon (Corg) and biogenic opal (BSi, diatoms) fluxes were twofold to threefold higher at the coastal upwelling site compared to the offshore site, respectively, and showed higher seasonality with flux maxima in spring. A relationship between winter and spring BSi fluxes to the North Atlantic Oscillation index was best expressed at the offshore site CBmeso. Lithogenic (dust) fluxes regularly peaked in winter when frequent low‐altitude dust storms and deposition occurred, decreasing offshore by about threefold. We obtained a high temporal match of short‐term peaks of BSi and dust fluxes in winter to spring at the inner site CBeu. We found synchronous flux variations at both sites and an anomalous year 2005, characterized by high BSi and Corg fluxes under a low North Atlantic Oscillation. Corg and BSi fluxes revealed a decreasing trend from 2006 to 2016 at the coastal site CBeu, pointing to coastal upwelling relaxation during the last two decades. The permanent offshore upwelling zone of the deflected Canary Current represented by the flux record of CBmeso showed no signs of increasing upwelling as well which contradicts the Bakun hypothesis. Key Points: Organic carbon fluxes decreased at the coastal upwelling site CBeu (2003‐2016). Both study sites show no signs of increasing upwellingWe found a high temporal accordance of short‐term peaks of biogenic silica and dust fluxes in winter to spring at the inner site CBeuThe year 2005 is exceptional with a decoupling of coastal upwelling forced by NAO and particle fluxes [ABSTRACT FROM AUTHOR]

Abstract In recent years, due to the increasing concerns about their negative impact on wildlife and possible toxicity to living organisms (including humans), microplastics have become the subject of intense investigations. In the ocean, microplastics can be easily ingested by numerous marine organisms because of their small size (<5 mm). The Northwest African upwelling system is an important fishery area, and the present study is the first one in the region to reveal the presence of microplastic particles in the digestive tract of Atlantic chub mackerel (Scomber colias). From the 120 examined fish gastrointestinal tracts, 78.3% contained some type of microplastics, 74.2% contained fibres, 17.5% plastic fragments, and 16.7% paint. More studies are needed on fish, but S. colias is a candidate for being a good indicator of microplastic contamination in the region. Highlights • Ingestion of microplastics by fish around the Canary Islands was documented for the first time. • Microplastics were found in the digestive tract of 78.4% of the sampled fish. • Fibres comprised 74.2% of the microplastics found. • We hypothesize that high fibres incidence may be related to untreated wastewater discharges. • Scomber colias could be a good indicator of microplastic contamination in the region. [ABSTRACT FROM AUTHOR]

Highlights • Zooplankton vertical distribution, migrant biomass, and respiratory flux were studied. • Migrant biomass was estimated by sampling during day and night in 0–900 m depth. • The electron transfer system enzymatic activity was measured as a proxy for respiration. • Migrant biomass and the respiratory flux showed the strongest correlation. • Active flux estimated suggests a significant transport to the mesopelagic zone. [ABSTRACT FROM AUTHOR]

Abstract Brittle stars constitute a common and highly diverse component of epibenthic communities, and they can form dense aggregations on the seabed of all oceans worldwide. Nevertheless, there is limited information on the diversity and distribution of these echinoderms in Northwest Africa. Between 2004 and 2012, 10 multidisciplinary Spanish and Norwegian surveys were conducted off Northwest Africa—between the Strait of Gibraltar and Sierra Leone border—from a depth of 19 to 1888 m. During these surveys, we sampled 1298 stations, and about one million individuals and 124 kg of brittle stars were collected from 502 stations. Forty-two species belonging to eight ophiuroid families considered as suspension feeders were collected from 296 stations and represented 93.4% of the total abundance and 75% of the total ophiuroid-specific richness. Ophiacanthidae was the richest and most abundant family, with 15 species and estimated densities up to almost 4 × 105 by 0.1 square kilometre. The other families found abundantly were Amphiuridae, Ophiotrichidae and Ophiactidae, represented by six, five and four species each, respectively. Ophiotrichidae, Ophiacanthidae and Gorgonocephalidae presented the largest biomass among the suspension-feeder families (35.5%, 33.8% and 28.2%, respectively), and Ophiotrichidae is a well-represented family along the Northwest African coast. The most remarkable concentrations and highest diversity values were detected on the upper slope (depth, 400–600 m) off Western Sahara. Between 24°N and 22°N, we collected huge concentrations of Ophiacantha abyssicola and up to six species per station. This area has permanent and intense upwelling conditions and is out of the minimum oxygen zone. We also noted significant densities and richness at Cape Ghir and Cape Blanc, where important filaments of nutrient-rich waters occur, and at Guinea-Bissau, which is affected by nutrient river inputs. The multivariate analysis clearly separated the brittle stars into two main assemblages, across latitudinal and bathymetrical gradients: northern latitude (Morocco and Northern Sahara) from the area south of 24°N and from the continental shelf–upper slope to the deep slope. Highlights • Northwest Africa constitutes one of the most highly productive areas worldwide. • Suspension-feeding ophiuroids showed an absolute dominance in this region. • Ophiacanthidae family exhibited remarkable concentrations on the Western Sahara slope. • Environmental factors related to water masses seem to drive the distribution pattern. [ABSTRACT FROM AUTHOR]

Eastern boundary upwelling provides the conditions for high marine productivity in the Canary Current System off NW-Africa. Despite its considerable importance to fisheries, knowledge on this marine ecosystem is only limited. Here, parasites were used as indicators to gain insight into the host ecology and food web of two pelagic fish species, the commercially important species Trichiurus lepturus Linnaeus, 1758, and Nealotus tripes Johnson, 1865. Fish specimens of T. lepturus (n = 104) and N. tripes (n = 91), sampled from the Canary Current System off the Senegalese coast and Cape Verde Islands, were examined, collecting data on their biometrics, diet and parasitisation. In this study, the first parasitological data on N. tripes are presented. T. lepturus mainly preyed on small pelagic Crustacea and the diet of N. tripes was dominated by small mesopelagic Teleostei. Both host species were infested by mostly generalist parasites. The parasite fauna of T. lepturus consisted of at least nine different species belonging to six taxonomic groups, with a less diverse fauna of ectoparasites and cestodes in comparison to studies in other coastal ecosystems (Brazil Current and Kuriosho Current). The zoonotic nematode Anisakis pegreffii occurred in 23% of the samples and could pose a risk regarding food safety. The parasite fauna of N. tripes was composed of at least thirteen species from seven different taxonomic groups. Its most common parasites were digenean ovigerous metacercariae, larval cestodes and a monogenean species (Diclidophoridae). The observed patterns of parasitisation in both host species indicate their trophic relationships and are typical for mesopredators from the subtropical epi- and mesopelagic. The parasite fauna, containing few dominant species with a high abundance, represents the typical species composition of an eastern boundary upwelling ecosystem.

Abstract: Life history theory states that individual fitness in one stage of life is conditioned by what occurred in previous stages. In migratory species, reproductive effort during breeding has often been found to influence body condition, molt schedule, self‐provisioning and migration of individuals in subsequent seasons (i.e., carryover effects of breeding). However, there is a current uncertainty in understanding how long‐distance migrants trade off among such energy‐demanding activities (i.e., breeding, molting and migrating). To provide evidence to the field, we experimentally reduced the parental effort of a long‐lived Procellariform, the Cory's shearwater (Calonectris borealis), by inducing failure at the incubation stage. Treatment and control birds were tracked during their subsequent migration by means of light‐level and immersion loggers and sampled for six specific feathers (molted at different periods along the migratory cycle) upon the recovery of the loggers 1 yr later. Feathers were used to perform stable isotope analysis (SIA) and determine corticosterone levels (CORT). By these means, we evaluated the effect of breeding effort on migratory strategy, at‐sea activity patterns, molt patterns, and levels of stress experienced by birds along the non‐breeding period. We did not detect any difference between birds in the induced failure group and successful breeders in terms of spatio‐temporal distribution: all birds shared common foraging areas throughout the study period and the timing of major phenological events did not differ. Failed birds significantly advanced their molt, as revealed by SIA and flying activity patterns. The stress levels of failed birds, inferred through CORT concentrations in feathers, were found to be consistently lower than in successful breeders, through the end of the breeding to the non‐breeding period. Thus, we provide robust evidence that the costs of reproduction can be physiologically mediated from the breeding to the non‐breeding period through molting schedules and CORT levels. However, we failed to detect clear effects on migratory behavior or subsequent breeding success, suggesting that costs of breeding in long‐lived species may be rapidly buffered during the post‐breeding period, as would be expected from life history theory. [ABSTRACT FROM AUTHOR]

Eastern boundary upwelling provides the conditions for high marine productivity in the Canary Current System off NW-Africa. Despite its considerable importance to fisheries, knowledge on this marine ecosystem is only limited. Here, parasites were used as indicators to gain insight into the host ecology and food web of two pelagic fish species, the commercially important species Trichiurus lepturus Linnaeus, 1758, and Nealotus tripes Johnson, 1865. Fish specimens of T. lepturus (n D 104) and N. tripes (n D 91), sampled from the Canary Current System off the Senegalese coast and Cape Verde Islands, were examined, collecting data on their biometrics, diet and parasitisation. In this study, the first parasitological data on N. tripes are presented. T. lepturus mainly preyed on small pelagic Crustacea and the diet of N. tripes was dominated by small mesopelagic Teleostei. Both host species were infested by mostly generalist parasites. The parasite fauna of T. lepturus consisted of at least nine different species belonging to six taxonomic groups, with a less diverse fauna of ectoparasites and cestodes in comparison to studies in other coastal ecosystems (Brazil Current and Kuriosho Current). The zoonotic nematode Anisakis pegreffii occurred in 23% of the samples and could pose a risk regarding food safety. The parasite fauna of N. tripes was composed of at least thirteen species from seven different taxonomic groups. Its most common parasites were digenean ovigerous metacercariae, larval cestodes and a monogenean species (Diclidophoridae). The observed patterns of parasitisation in both host species indicate their trophic relationships and are typical for mesopredators from the subtropical epi- and mesopelagic. The parasite fauna, containing few dominant species with a high abundance, represents the typical species composition of an eastern boundary upwelling ecosystem. [ABSTRACT FROM AUTHOR]

Cetaceans of Morocco have been poorly studied to date, and only sporadic information comes from scientific cruises for this group. In an attempt to learn more on the occurrence, distribution and relative abundances of cetaceans in Morocco, a stranding database was reconstructed from various sources (stranding reports from state agencies and newspaper clippings). This inventory documented 205 cases of stranding between 1980 and 2009. Most of the strandings and most confirmed cases of interactions with human activity (fishing, for dolphins; collisions, for whales) were reported in the Strait of Gibraltar and adjacent areas from the Atlantic and the Mediterranean. Sixteen species were identified from the stranding database, of which seven species were the most abundant. These were striped dolphins, common dolphins, bottlenose dolphins, fin whales, sei whales, sperm whales and long-finned pilot whales. The fin and sei whales were present throughout the year and stranding of common and striped dolphins were minimal between September and December. The fin, sei and sperm whales seem to be present in Moroccan waters at birth and at different stages of their life cycle. Establishing an observation network of sufficient and sustainable density in Morocco is the most likely way to collect robust data for the calculation of credible population indicators for cetaceans. Monitoring will certainly improve through better collaboration among Moroccan institutions and a greater awareness in Moroccan civil society of environmental issues. [ABSTRACT FROM AUTHOR]

Climatology-based storage rate of anthropogenic CO 2 (C ant , referred to year 2000) in the North-East Atlantic (53 ± 9 kmol s −1 , 0.020 ± 0.003 Pg-C yr −1 ) is described on annual mean terms. C ant advection (32 ± 14 kmol s −1 ) occurs mostly in the upper 1800 m and contributes to 60% of the C ant storage rate. The Azores and Portugal Currents act as ‘C ant streams’ importing 389 ± 90 kmol s −1 , most of which recirculates southwards with the Canary Current (−214 ± 34 kmol s −1 ). The Azores Counter Current (−79 ± 36 kmol s −1 ) and the northward-flowing Mediterranean Water advective branch (−31 ± 12 kmol s −1 ) comprise secondary C ant export routes. By means of C ant transport decomposition, we find horizontal circulation to represent 11% of the C ant storage rate, while overturning circulation is the main driver (48% of the C ant storage rate). Within the domain of this study, overturning circulation is a key mechanism by which C ant in the upper layer (0–500 dbar) is drawdown (74 ± 14 kmol s −1 ) to intermediate levels (500–2000 dbar), and entrained (37 ± 7 kmol s −1 ) into the Mediterranean Outflow Water to form Mediterranean Water. This newly formed water mass partly exports C ant to the North Atlantic at a rate of −39 ± 9 kmol s −1 and partly contributes to the C ant storage in the North-East Atlantic (with up to 0.015 ± 0.006 Pg-C yr −1 ). Closing the C ant budget, 40% of the C ant storage in the North-East Atlantic is attributable to anthropogenic CO 2 uptake from the atmosphere (21 ± 10 kmol s −1 ). [ABSTRACT FROM AUTHOR]

Several studies in upwelling regions have suggested that mesoscale structures, such as eddies and filaments, contribute substantially to the long-range transport of the organic carbon from the nearshore region of production to the offshore region of remineralization. Yet this has not been demonstrated in a quantitative manner for the entire Canary Upwelling System (CanUS). Here, we fill this gap using the Regional Oceanic Modeling System (ROMS) coupled to a Nutrient, Phytoplankton, Zooplankton, and Detritus (NPZD) ecosystem model. We run climatological simulations on an Atlantic telescopic grid with an eddy-resolving resolution in the CanUS. Using both a Reynolds flux decomposition and structure-identification algorithms, we quantify and characterize the organic carbon fluxes driven by filaments and eddies within the upper 100 m and put them in relationship to the total offshore transport. Our analyses reveal that both coastal filaments and eddies enhance the offshore flux of organic carbon, but that their contribution is very different. Upwelling filaments, with their high speeds and high organic carbon concentrations, transport this carbon offshore in a very intense, but coastally-confined, manner, contributing nearly 80 % to the total flux at 100 km offshore distance. The filament contribution tapers off quickly to near zero values at 1000 km distance, leading to a strong offshore flux divergence that is the main lateral source of organic carbon in the first 500 km offshore. Some of this divergence is also due to the filaments inducing a substantial vertical subduction of the organic carbon below 100 m. Owing to the temporal persistence and spatial recurrence of filaments, the filament transport largely constitutes a time-mean flux and only to a limited degree represents a turbulent flux. At distances beyond 500 km from the coast, eddies dominate the mesoscale offshore transport. Although their contribution represents only 20 % of the total offshore flux and of its divergence, eddies, especially cyclones, transport organic carbon offshore to distances as great as 2000 km from the coast. The eddy transport largely represents a turbulent flux, but striations in this transport highlight the existence of typical formation spots and recurrent offshore propagation pathways. While they propagate slowly, eddies are an important organic carbon reservoir for the open waters, since they contain on average a third of the offshore organic carbon, two third of which is found in cyclones. Our analysis confirms the importance of mesoscale processes for the offshore organic carbon transport and the fueling of the heterotrophic activity in the eastern subtropical North Atlantic, and highlights the need to consider the mesoscale flux in order to fully account for the three-dimensionality of the marine biological pump. [ABSTRACT FROM AUTHOR]

Hydrographic measurements together with Ship mounted Acoustic Doppler Current Profilers and Lowered Acoustic Doppler Current Profilers (LADCP) obtained in October 2014 are used to describe water masses, geostrophic circulation and mass transport of the Canary Current System, as the Eastern Boundary of the North Atlantic Subtropical Gyre. Geostrophic velocities are adjusted to velocities from LADCP data to estimate an initial velocity at the reference layer. The adjustment results in a northward circulation at the thermocline layers over the African slope from an initial convergent flow. Final reference velocities and consequently absolute circulation are estimated from an inverse box model applied to an ocean divided into 13 neutral density layers. This allows us to evaluate mass fluxes consistent with the thermal wind equation and mass conservation. Ekman transport is estimated from the wind data derived from the Weather Research and Forecasting model. Ekman transport is added to the first layer and adjusted with the inverse model. The Canary Current located west of Lanzarote Island transports to the south a mass of − 1.5 ± 0.7 Sv (1 Sv = 10 6 m 3 s − 1 ≈ 10 9 kg s − 1 ) of North Atlantic Central Water at the surface and thermocline layers (~ 0–700 m). In fall 2014, hydrographic data shows that the Canary Current in the thermocline (below at about 80 m depth to ~ 700 m) recirculates to the north over the African slope and flows through the Lanzarote Passage. At intermediate layers (~ 700–1400 m), the Intermediate Poleward Undercurrent transports northward a relatively fresh Antarctic Intermediate Water in the range of 0.8 ± 0.4 Sv through the Lanzarote Passage and west of Lanzarote Island beneath the recirculation of the Canary Current. [ABSTRACT FROM AUTHOR]

A compilation of measurements of net community production (NCP) in the upper waters of the eastern subtropical North Atlantic had suggested net heterotrophic conditions, purportedly supported by the lateral export of organic carbon from the adjacent, highly productive Canary Upwelling System (CanUS). Here, we quantify and assess this lateral export using the Regional Ocean Modeling System (ROMS) coupled to a nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model. We employ a new Atlantic telescopic grid with a strong refinement towards the northwestern African shelf to combine an eddy-resolving resolution in the CanUS with a full Atlantic basin perspective. Our climatologically forced simulation reveals an intense offshore flux of organic carbon that transports about 19 TgC yr-1 away from the nearshore 100 km over the whole CanUS, amounting to more than a third of the NCP in this region. The offshore transport extends beyond 1500 km into the subtropical North Atlantic, adding organic carbon along the way to the upper 100m at rates of between 8 and 34% of the alongshore average NCP as a function of offshore distance. Although the divergence of this lateral export of organic carbon enhances local respiration, the upper 100m layer in our model remains net autotrophic in the entire eastern subtropical North Atlantic. However, the vertical export of this organic carbon and its subsequent remineralization at depth makes the vertically integrated NCP strongly negative throughout this region, with the exception of a narrow band along the northwestern African shelf. The magnitude and efficiency of the lateral export varies substantially between the different subregions. In particular, the central coast near Cape Blanc is particularly efficient in collecting organic carbon on the shelf and subsequently transporting it offshore. In this central subregion, the offshore transport adds as much organic carbon as nearly 60% of the local NCP to the upper 100 m, giving rise to a sharp peak of offshore respiration that extends to the middle of the gyre. Our modeled offshore transport of organic carbon is likely a lower-bound estimate due to our lack of full consideration of the contribution of dissolved organic carbon and that of particulate organic carbon stemming from the resuspension of sediments. But even in the absence of these contributions, our results emphasize the fundamental role of the lateral redistribution of the organic carbon for the maintenance of the heterotrophic activity in the open sea. [ABSTRACT FROM AUTHOR]

The regional ocean circulation within the Canary Upwelling System between 31°N and 35°N is studied using numerical tools. Seasonal mean and near-instantaneous velocity fields from a previously-generated climatological Regional Ocean Modelling System (ROMS) solution of the Canary Basin are used to force a series of offline Lagrangian particle-tracking experiments. The primary objective is to identify the pathways through which water parcels arrive at the upwelling region north of Cape Ghir. Examining year-long pathways, the Azores Current contributes over 80% of particles annually, of which a large proportion arrive directly from offshore (from the northwest), while others travel along the shelf and slope from the Gulf of Cadiz. The remaining ~20% originate within the Gulf of Cadiz or come from the south, although the southern contribution is only significant in autumn and winter. When season-long pathways are considered, the alongshore contributions become increasingly important: northern contributions reach 40% in spring and summer, while southern values exceed 35% in winter. This study also shows that coastal upwelling changes both spatially and temporally. Upwelling becomes intensified near Cape Beddouza, with most upwelling occurring within ~40 km from shore although significant values may reach as far as 120 km offshore north of Cape Beddouza; at these locations the offshore integrated upwelling reaches as much as 4 times the offshore Ekman transport. In the Cape Beddouza area (32°N to 33°N), upwelling is negligible in February but intensifies in autumn, reaching as much as 3 times the offshore Ekman transport.

Seasonal and interannual variability of the Canary Current on its passage through the Canary archipelago and between 20-35°N and 10-20°N are studied with long series of historical tide gauge, sea surface temperature and hydrographic data. The variability of winds is more seasonal in the north of the area, where they are weak and perpendicular to the coast in winter, than in the south, where winds are roughly parallel to shore all year though strongest in summer. Temperature and salinity data maps show a curved structure indicative of the subtropical gyre, which varies seasonally from North to South and from the open ocean to the coast. Dynamic height analyses show this seasonal variation of the gyre to depths of 200 m and indicate the existence of a meander-like diversion around the Canary Islands. The sea level in the Canary Islands also indicates a strong seasonal variation of the north Atlantic subtropical gyre. The southward geostrophic surface flow, derived from sea surface slope, was strongest during spring and summer at the eastern islands while it was strongest in winter at the outermost islands. The spatially averaged flow between the innermost and outermost islands shows the strongest southward flow in winter. Interannual variation of the flow between these islands, investigated during two periods, 1950-1956 and 1960-1973, reveals a mainly southward flow, although several show a northward tendency. The maximum equatorward velocity of the current in both periods is around 5 cm s-1, indicating a weak current.

The flow pattern of the North Atlantic Subtropical Gyre (NASG) is simulated using a highly idealised one-layer quasi-geostrophic wind-driven model. The novel feature of the model is the specification of the eastern boundary conditions. This is an upwelling favourable region with a quasi-permanent southward flowing coastal jet, which is fed by the eastern branch of the Canary Current. The corresponding boundary conditions are non-zero normal flux and constant potential vorticity, the latter being consistent with the generation of anticyclonic vorticity by the coastal jet. We examine the sensitivity of the model to the eastern boundary conditions and compare the results with recent observations for the region.

Little is known about the effect of ocean fronts on pollutants dynamics, particularly organic pollutants. Since fronts are associated with convergent currents and productive fishing grounds, any possible convergence of pollutants at fronts would raise concerns. The focus here is on relatively persistent organic pollutants, POPs, as non-persistent organic pollutants are rarely found in the open ocean. Results from recent cruises in the Atlantic Ocean are examined for POP distributions across ocean fronts in (i) the Canary Current; (ii) the Gulf Stream; and (iii) the Amazon and Rio de la Plata Plumes. Few studies achieved a spatial resolution of 10–20 km, while most had 100–300 km between adjacent stations. The majority of the well-resolved studies measured perfluorinated compounds (PFCs), which seem particularly well suited for frontal resolution. In the NE Atlantic, concentrations of PFCs sharply decreased between SW Europe and NW Africa upon crossing the Canary Current Front at 24–27°N. In the Western Atlantic, the PFC concentrations sharply increased upon entering the Amazon River Plume and Rio de la Plata Plume. In the NW Atlantic, concentrations of several pollutants such as polycyclic aromatic hydrocarbons are very high in Rhode Island Sound, decreasing to below detection limit in the open ocean. The more persistent and already phased-out polychlorinated biphenyls (PCBs) displayed elevated concentrations in the Gulf Stream and Rhode Island Sound, thereby highlighting the importance of ocean fronts, along-front currents, and cross-frontal transport for the dispersal of PCBs. [ABSTRACT FROM AUTHOR]

Abstract: A new methodology to derive an SST-based upwelling index was based on a rigorous spatial analysis of satellite SST fields and their variability, by referring to previous works, from Wooster et al. (1976) to Santos et al. (2011). The data was precautiously processed by considering data quality aspects (including cloud cover) and the best way to derive accurate coastal SST and its offshore reference. The relevance of the developed index was evaluated by comparing its spatial and seasonal consistency against two wind-based indices as well as with the previous SST-based indices, largely superseding these later ones in term of overall quality and spatio-temporal dynamic. Our index adequately describes the spatio-temporal variability of the coastal upwelling intensity in the Canary Current upwelling system and has the advantage of describing complementary aspects of the coastal dynamics of the region that were not covered by Ekman-based indices. The proposed methodology is generic and can be easily applicable to various coastal upwelling systems, especially the four major eastern boundary upwelling ecosystems. [Copyright &y& Elsevier]

The spatial distribution of fish larvae was studied in the Canaries- African Coastal Transition Zone, outside the strong upwelling season. An onshore-offshore transition in the larval fish community structure was observed, from a coastal assemblage dominated by small pelagics (sardine, anchovy, mackerel), bounded by the upwelling front, to an offshore assemblage dominated by mesopelagic species (mainly Myctophidae, Phosichthydae, Gonostomatidae). Distribution of the neritic larvae was deeply influenced by the intense mesoscale activity found in the area, both horizontally (larvae were advected offshore but were always retained within the upwelling area) and vertically (larvae were deepened in the vicinity of two anticyclonic eddies). A combined effect of the upwelling front and a cyclonic-anticyclonic eddy dipole is likely the successful retention mechanism for these larvae. These results support the current belief that retention may be higher than previously thought in upwelling areas. Oceanic larvae were also collected in higher abundances near the front and an anticyclonic eddy. Neritic and oceanic larvae frequently showed a differentiated position in the water column, although they sometimes coexisted. Finally, larval connectivity between Islands within the Canary archipelago is suggested. The present study thus contributes to the understanding of the complex dispersal and retention processes in the Canaries- African Coastal Transition Zone. However, results also highlight the poor knowledge of this region compared with the other three main Eastern Boundary Upwelling Systems in terms of ichthyoplankton dynamics. The importance of routine monitoring programs of commercial and non-commercial species in the area is emphasized. [ABSTRACT FROM AUTHOR]

Highlights: [•] The methodology can be applied to any tidal coastal zone. [•] The entire study area is vulnerable to micro-plastic pollution. [•] On Lanzarote, the pollution reached a maximum of 109g of plastic in 1l of sediment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Time–space variability in upwelling conditions influenced the structure of plankton in an area of permanent upwelling. [•] Microplanktonic diatoms and auto/mixotrophic dinoflagellates made the highest contributions to photoautotrophic C-biomass. [•] Nanoplankton usually made the largest contributions to total Chl-a. [•] Mean H:A biomass ratios were <1 after the inclusion of mixotrophy but >1 without it. [•] Lower nutrients in upwelled waters is possibly linked to the presence of mixed assemblages of auto- and mixotrophs. [Copyright &y& Elsevier]

The Canary Current has experienced a progressive warming and a decrease in productivity over the last decades. In order to study the effect of stratification in these waters, we conducted a weekly sampling at one station (28°04′N 15°21′E) located ∼3nmi offshore in the 100m isobath, at the edge of the island shelf of Gran Canaria Island (Canary Islands). The sampling was performed over two and a half years, from January 2005 to June 2007, covering the most productive season in subtropical waters, the so-called late winter bloom, three times. The variables measured were temperature, chlorophyll a (Chl a), heterotrophic and autotrophic prokaryotes, pico-, nano-, micro- and mesozooplankton biomass. During 2005, the mixing of the water column started in January, while in 2007 the mixing period was delayed one month. Between years, temperature showed an increase of 0.5°C, and Chl a decreased to half of the initial concentration (from ∼0.50 to ∼0.25mg Chl a m−3). Autotrophic picoplankton and heterotrophic prokaryotes decreased between 2005 and 2007. However, neither nanoflagellates nor microplankton showed this decrease. The mesozooplankton biomass outburst lasted for three months in 2005, two in 2006, and only one month in 2007. Contrary to previously hypothesized size relationships, we did not observe an increase in the contribution of autotrophic picoplankton to total phytoplankton during periods of higher stability of the water column, but the opposite. We explain this surprising finding by possible top-down effects and by the success of motile morphotypes of algae (i.e., small dinoflagellates) under stable, nutrient-limited, conditions. Overall, the results suggest that small inter-annual differences in temperature, resulting in a tendency towards more stratified waters, give rise to important changes in the structure of the pelagic ecosystem in subtropical waters through a combination of bottom-up and top-down effects. [ABSTRACT FROM AUTHOR]

Aim Apical pelagic species forage in predictable habitats, and their movements should signal biologically and ecologically significant areas of the marine ecosystem. Several countries are now engaged in identifying these areas based on animal tracking, but this is often limited to a few individuals from one breeding population, which may result in biased portrayals of the key marine habitats. To help identify such foraging areas, we compiled tracking data of a marine top predator from the main breeding colonies in the Central Macaronesia. Location North-east Atlantic Ocean. Methods Over seven years, we tracked the foraging movements of Cory's shearwaters ( Calonectris borealis) from several populations during the chick-rearing period using global positioning system and platform terminal transmitter devices. Results We obtained foraging trips from 174 shearwaters breeding on six important colonies representative of the range occupied in the Macaronesian Archipelagos of Madeira, Salvages and Canaries. Our results show that birds orient and move rapidly towards the closest neritic waters over the African continental shelf. Birds from different colonies show substantial spatial segregation in their foraging grounds but consistently overlap in some specific foraging areas along the Canary Current characterized by high productivity. By weighting the use of foraging grounds according to the size of each study population, we inferred the overall exploitation of such areas. Main conclusions Our meta-population approach provides a more comprehensive picture of space use from both perspectives: the studied species and the Canary Current system. Foraging grounds consistently used by several populations may not be adequately identified by tracking a single population, and therefore, multiple population tracking studies are needed to properly delineate key conservation areas and inform conservation planning in the marine ecosystem. Finally, we highlight the long-term stability and sustainability of identified foraging areas and propose that countries with geographical jurisdictions over the Canary Current area should work towards multilateral agreements to set management plans for this key marine ecosystem. [ABSTRACT FROM AUTHOR]