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The green macroalga Caulerpa ashmeadii was recently found in the North-eastern Atlantic Ocean, on the southern coast of Porto Santo Island (Madeira archipelago). Caulerpa ashmeadii was detected in a subtidal soft-bottom forming scattered patches, mostly among the green calcareous macroalgae Halimeda incrassata and Penicillus capitatus, within a depth range of 18–26 m. Some isolated patches were also observed in bare sand. The species is currently distributed over an estimated area of approximately 0.22 km2. Caulerpa ashmeadii may represent a recent settler (Nov. 2020), although the hypothesis of the species being present elsewhere in Porto Santo prior to our discovery cannot be discarded. Alternatively, the presence of C. ashmeadii in Porto Santo may indicate the influence of climate change on the composition and structure of benthic communities in the Webbnesia region, which further stresses the importance of conducting more intensive biological and environmental monitoring programmes. Overall, this new record constitutes an exceptional eastern expansion of this marine species by more than 4200 km, comprising its first register in the Eastern Atlantic Ocean.

Global marine conservation remains fractured by an imbalance in research efforts and policy actions, limiting progression towards sustainability. Rhodolith beds represent a prime example, as they have ecological importance on a global scale, provide a wealth of ecosystem functions and services, including biodiversity provision and potential climate change mitigation, but remain disproportionately understudied, compared to other coastal ecosystems (tropical coral reefs, kelp forests, mangroves, seagrasses). Although rhodolith beds have gained some recognition, as important and sensitive habitats at national/regional levels during the last decade, there is still a notable lack of information and, consequently, specific conservation efforts. We argue that the lack of information about these habitats, and the significant ecosystem services they provide, is hindering the development of effective conservation measures and limiting wider marine conservation success. This is becoming a pressing issue, considering the multiple severe pressures and threats these habitats are exposed to (e.g., pollution, fishing activities, climate change), which may lead to an erosion of their ecological function and ecosystem services. By synthesizing the current knowledge, we provide arguments to highlight the importance and urgency of levelling-up research efforts focused on rhodolith beds, combating rhodolith bed degradation and avoiding the loss of associated biodiversity, thus ensuring the sustainability of future conservation programs.

[Abstract] Rhodolith seabeds are ‘ecosystem engineers’ composed of free-living calcareous red macroalgae, which create extensive marine habitats. This study addressed how depth influenced the structure (size and morphology) of rhodoliths and the abundance of associated floral and faunal epibionts across the Eastern Atlantic Ocean. Sampling was carried out at two sites within five regions (Brittany, Galicia, Madeira, Gran Canaria, and Principe Island), from temperate to tropical, covering a latitudinal gradient of 47°, in three depth strata (shallow, intermediate and deep), according to the rhodolith bathymetrical range in each region. Depth typically affected the rhodolith size at all regions; the largest nodules were found in the intermediate and deep strata, while rhodolith sphericity was larger at the shallow depth strata. Higher biomasses of attached macroalgae (epiphytes) were observed at depths where rhodoliths were larger. The abundance of epifauna was variable across regions and depth strata. In general, the occurrence, structure, and abundance of the associated biota across rhodolith habitats were affected by depth, with local variability (i.e., sites within regions) often displaying a more significant influence than the regional (large-scale) variation. Overall, this study showed that the rhodolith morphology and associated epibionts (flora and fauna) were mostly affected by depth, irrespective of latitude.

Aims The present study is the first attempt to grasp the scale and richness of marine biological invasions in Macaronesia. We pioneered a comprehensive non-native species (NNS), inventory in the region to determine their diversity patterns and native distribution origins. NNS were defined here as the result of both introductions and range expansions. We also used statistical modelling to examine relationships among NNS richness, anthropogenic activities, demographic and geographical variables across Macaronesia. Location Macaronesia. Methods A comprehensive literature search was conducted for marine NNS records in Macaronesia, registering the first record's location and year from 1884 to 2020. We used univariate and multivariate analyses to evaluate differences and similarities in community composition. By applying a Generalized Linear Model (GLM), we tested hypotheses regarding NNS richness as a function of anthropogenic activities, demographic and geographical variables. Results A total of 144 marine non-native species (NNS) were recorded for the whole of Macaronesia. The highest NNS richness was registered in the Canary Islands (76 NNS), followed by the Azores (66 NNS), Madeira (59 NNS) and finally Cabo Verde (18 NNS). Some differences amongst archipelagos were observed, such as the high number of non-native macroalgae in the Azores, fishes in the Canary Islands and tunicates in Cabo Verde. Overall, macroalgae, tunicates and bryozoans were the predominant taxonomic groups in the Macaronesian archipelagos. Madeira and Canary Islands were the archipelagos with more similarity in marine NNS, and Cabo Verde the most divergent. Finally, GLM suggested that non-native richness patterns across Macaronesia were dependent on the considered archipelago and strongly affected by (1) minimum distance to the mainland, (2) the total number of ports and marinas and (3) total marinas area (km2). Conclusions The model results and NNS listing in the present study will likely raise t

Increased pollution in the coastal areas may cause changes in the biodiversity of marine organisms depending upon their physiological capacity and resilience to thrive under stressing environmental conditions. The present research evaluates the heavy metals pollution degree of coastal waters using the macroalgae Ericaria selaginoides as bioindicator along the Atlantic coast of Morocco. Eight stations were chosen: two located near Eljadida city, three nearby Safi city and three around the city of Essaouira. Results showed that the heavy metal content in the thalli of E. selaginoides, in seawater and sediment varied seasonally. At the same time, it was negatively correlated with algal biodiversity onsite. However, the Chemical Oxygen Demand was significantly higher at the polluted station S5 than at other stations, while Dissolved Oxygen and Biological Oxygen Demand were lower. E. selaginoides accumulated metals in the following order Fe > Zn > Mn > Cu > Ni > Pb > Cr > Cd. In conclusion, E. selaginoides is overall more resilient to heavy metal pollution than other marine organisms in the Atlantic coast of Morocco, as indicated by substantially elevated concentrations of heavy metals in some sites. Our results support that E. selaginoides would be a suitable bioindicator for monitoring of heavy metals in polluted coastal areas.

Mapping and Assessment of Ecosystems and their Services (MAES) has been widely applied on the European Union (EU) mainland, whereas the EU Overseas entities still bear potential for implementation. This paper presents novel applications of the MAES procedure in the EU Outermost Regions and Overseas Countries and Territories ("EU Overseas"). Eight case studies from different geographical areas were analysed through a comparative assessment by applying an established framework following key steps in the MAES process, in order to stipulate lessons learned and recommendations for MAES in the EU Overseas. These key steps include the identification of policy questions, stakeholder networks and involvement, application of MAES methods, dissemination and communication and implementation. The case studies were conducted and analysed under the umbrella of the EU MOVE pilot project, including the Azores, the Canary Islands, Saint Martin, French Guiana, Martinique, Reunion Island and the Falkland Islands. Each case study represented different governance, policy and decision-making frameworks towards biodiversity and environmental protection. Case studies predominantly addressed the policy domains of Nature and Biodiversity Conservation and Marine and Maritime Policy. Ecosystem Services (ES) were assessed across a wide range of themes, biomes and scales, focusing on terrestrial, coastal and marine ecosystems. Results show that the implementation of the case studies was accompanied by extensive communication and dissemination activities. First success stories were visible, where the MAES exercise led to meaningful uptake of the ES concept to policies and decision-making. Yet, there is still work to be done - major bottlenecks were identified related to the MAES implementation centring around financial resources, training and technical expertise. Addressing these aspects can contribute to an enhanced implementation of MAES in the EU Overseas in the future.

This paper analyzes for the first time a two-loop sliding-mode control (SMC) of a high-order converter supplying a constant power load (CPL). The converter is a single-switch quadratic buck structure (QBC) interfacing a domestic 380 V DC bus to a CPL requiring a regulated voltage of 48 V DC. The converter is unstable in the absence of control and even after the insertion of an inner loop based on SMC of the input inductor current. The addition of an appropriate linear outer loop establishing the reference to the inner loop stabilizes the system and provides output voltage regulation. The regulated QBC shows a fast recovery of the output voltage with negligible overshoot in response to step-up changes of the output power or the input voltage. It is also shown that the implemented regulator for CPL supply can be used directly in the case of a constant current load (CCL) or a constant resistance load (CRL) resulting in similar performance to the CPL case. PSIM simulations and experimental results in a 400 W prototype are in good agreement with theoretical predictions.

© 2013 IEEE. A large-signal averaged model is obtained to analyze the startup response of a boost converter loaded with a constant power load (CPL) and a peak current mode control (CMC). An analytical methodology is developed for the stability analysis during both startup and steady state. The proposed model corresponds to two operating modes: 1) a reduced-order saturated model during startup mode and 2) an unsaturated full-order model taking place when the system reaches the vicinity of the steady state. The duration of the startup period is also determined using the same model. To verify the validity of the derived large-signal model and the theoretical results derived from it, numerical simulation results from this model are compared with those obtained from a detailed switched model and experimental measurements demonstrating that the model can faithfully predict both the large-signal dynamic response during startup as well as the steady-state regime of the system.

© 2013 IEEE. This article focuses on analyzing the fast-scale stability in a peak current-mode-controlled boost converter with a constant power load (CPL). Since with this kind of nonlinear loads the analytical expression of the discrete-time model is not available and the existing averaged models are inadequate in describing accurately the fast-scale dynamics of these converters, a piecewise linear switched model is established by approximating the CPL by a composite linear load. The model is first demonstrated to predict accurately the same bifurcation points predicted by the switched model using the nonlinear load. The bifurcation analysis using the Floquet theory and the resulting monodromy matrix and its eigenvalues loci clearly show the effect of system parameters on its stability. The fast-scale stability boundaries in terms of suitable parameters are obtained by using eigenvalues analysis. The effect of the proportional gain of the voltage controller is studied. Finally, experimental results are further given to verify the theoretical analysis and simulation results obtaining a good agreement.

© 2013 IEEE. This paper proposes a modular photovoltaic (PV) dc-Nanogrid (dc-NG) architecture for residential applications. The proposed architecture is based on the Loss-Free Resistor (LFR) concept. The dc distribution bus is supplied by PV panels, ac utility and a storage battery. The storage battery is connected to the main dc bus through a dc-dc bidirectional converter (BDC). This battery has also an important role to ensure uninterruptible power supply to the critical loads and controls the power flow in the dc-NG. A mathematical model of the system is first derived and a stability analysis is carried out showing that the stability is guaranteed under certain mild conditions. Numerical simulations of a case study for two PV panels corroborate the theoretical predictions which have been finally confirmed by experimental measurements.

© 2020 by the authors. This paper focuses on the control design of a differential boost inverter when used in single-stage grid-tied PV systems. The inverter performs both Maximum Power Point Tracking (MPPT) at the DC side and Power Factor Correction at the AC side. At first, the state-space time-domain averaged model of the inverter is derived and the small signal frequency domain model is obtained using a quasi-static approximation in which the inverter is treated as a DC-DC converter with a slowly varying output voltage. Then, the controllers are designed using a three-loop strategy in which the inverter inductor currents loop is used for suitable compensation, the DC Photovoltaic (PV) voltage loop is used for MPPT and the output grid current loop is used for Power Factor Correction (PFC) and active power control. The selection of the control parameters is based on a compromise among suitable system performances such as settling time of the input PV voltage, the sampling period of the MPPT, total harmonic distortion of the output grid current, power factor as well as suppression of subharmonic oscillation for all the range of the operating duty cycle. The resulting design ensures that the oscillations of the voltage, current and power at the DC side and the grid current at the AC side are effectively controlled. The validity of the proposed control design is verified by numerical simulations performed on the switched model of the system demonstrating its robustness and fast response under irradiance variations and MPPT perturbations despite the nonlinearity and complexity of the system.