Influence of environmental variability on population traits of small pelagic fish in the Canary Islands (NW Africa, Spain)

Small pelagic fish (SPF) present relatively short life cycles, with fast growth, high mobility and plankton-base feeding. Therefore, they are highly sensitive to fluctuations in environmental conditions, including those related to Climate Change, and fishing. On the one hand, reproductive traits have been recently described for all these species in the Canary archipelago, which show a clear decreasing pattern of their sizes at first maturity during the last years (Jurado-Ruzafa et al., 2021). On the other hand, a regional increase in the sea water temperature has been observed in NW African waters during last decades (Vélez-Belchí et al., 2015). Foreseeing potential variations in the life history traits of SPF is critical for effective management measures in the current Global Warming scenario.FEM

Characterization of microzooplankton communities in a polluted coastal area integrating high-throughput sequencing and microscopy

The Mediterranean Sea is subjected to strong anthropogenic pressures that may be causing important ecosystem changes, particularly in coastal areas under high anthropogenic pressure. We characterized the composition of the microzooplankton community in a coastal area in the N Alboran Sea (SW Mediterranean) highly impacted by urban wastewater pollution. Two offshore outfalls release urban wastewater to the sea at a 40 m bottom depth, from a nearby town. We applied an integrative taxonomic approach, combining metabarcoding of the mitochondrial COI and the 18S rRNA genes with morphological microscopic identification of organisms, collected with a CalVET net (50 µm mesh). Hydrology was notably affected near the bottom at the vicinity of the submarine emissaries exit, presenting increased temperature and turbidity, and decreased salinity due to the urban freshwater discharge. Nutrient concentrations exceeded the Water Framework Directive limits; however, chlorophyll a concentrations were not very high, due to strong water column stratification. Microzooplankton communities (50-200 µm) were dominated by dinoflagellates (50-80% relative abundance), followed by copepods (copepodites and nauplii), eggs and cysts. We found significant differences in communities’ composition between the coastal shallow area and the offshore waters, driven by pollution and stratification.Consejería de Economía, Innovación y Ciencia de la Junta de Andalucía; Unión Europea, Fondo Europeo de Desarrollo Regional (P20_00743

Contribution of marine zooplankton time series to the United Nations Decade of Ocean Science for Sustainable Development

Zooplankton play a central role in marine trophic webs, influencing both biogeochemistry and productivity of the oceans. Changes in their communities are important indicators of overall ecosystem health and global change impacts. With increasing exploitation and pressures on the marine environment, there is a growing need for high-resolution monitoring of marine zooplankton to provide detailed information about seasonal to decadal changes at local, regional, and global scales. This crucial knowledge is gathered mainly through long-term time series, which are key to characterizing and forecasting changes in marine zooplankton assemblages. In this Introduction, and through the articles included in this Themed Article Set, we bring together new insights, issuing from data time series, into zooplankton population dynamics.We also take up the application of such time series to the understanding of global change impacts on marine ecosystems and in providing advice on sustainable management of marine ecosystem resources and services. We highlight the importance of maintaining and supporting long-term marine zooplankton time series as key contributors to the development and advancement of the United Nations’ Decade of Ocean Science for Sustainable Development Goal 13-Climate action and Goal 14-Life below water.2,27

Resilience dynamics and productivity-driven shifts in the marine communities of the Western Mediterranean Sea

Ecological resilience has become a conceptual cornerstone bridging ecological processes to conservation needs. Global change is increasingly associated with local changes in environmental conditions that can cause abrupt ecosystem reorganizations attending to system-specific resilience fluctuations with time (i.e. resilience dynamics). Here we assess resilience dynamics associated with climate-driven ecosystems transitions, expressed as changes in the relevant contribution of species with different life-history strategies, in two benthopelagic systems. We analysed data from 1994 to 2019 coming from a scientific bottom trawl survey in two environmentally contrasting ecosystems in the Western Mediterranean Sea—Northern Spain and Alboran Sea. Benthopelagic species were categorized according to their life-history strategies (opportunistic, periodic and equilibrium), ecosystem functions and habitats. We implemented an Integrated Resilience Assessment (IRA) to elucidate the response mechanism of the studied ecosystems to several candidate environmental stressors and quantify the ecosystems’ resilience. We demonstrate that both ecosystems responded discontinuously to changes in chlorophyll-a concentration more than any other stressor. The response in Northern Spain indicated a more overarching regime shift than in the Alboran Sea. Opportunistic fish were unfavoured in both ecosystems in the recent periods, while invertebrate species of short life cycle were generally favoured, particularly benthic species in the Alboran Sea. The study illustrates that the resilience dynamics of the two ecosystems were mostly associated with fluctuating productivity, but subtle and long-term effects from sea warming and fishing reduction were also discernible. Such dynamics are typical of systems with wide environmental gradient such as the Northern Spain, as well as systems with highly hydrodynamic and of biogeographical complexity such as the Alboran Sea. We stress that management should become more adaptive by utilizing the knowledge on the systems’ productivity thresholds and underlying shifts to help anticipate both short-term/less predictable events and long-term/expected effects of climate change.2,27

Novel Methodologies for Providing In Situ Data to HAB Early Warning Systems in the European Atlantic Area: The PRIMROSE Experience

Harmful algal blooms (HABs) cause harm to human health or hinder sustainable use of the marine environment in Blue Economy sectors. HABs are temporally and spatially variable and hence their mitigation is closely linked to effective early warning. The European Union (EU) Interreg Atlantic Area project “PRIMROSE”, Predicting Risk and Impact of Harmful Events on the Aquaculture Sector, was focused on the joint development of HAB early warning systems in different regions along the European Atlantic Area. Advancement of the existing HAB forecasting systems requires development of forecasting tools, improvements in data flow and processing, but also additional data inputs to assess the distribution of HAB species, especially in areas away from national monitoring stations, usually located near aquaculture sites. In this contribution, we review different novel technologies for acquiring HAB data and report on the experience gained in several novel local data collection exercises performed during the project. Demonstrations include the deployment of autonomous imaging flow cytometry (IFC) sensors near two aquaculture areas: a mooring in the Daoulas estuary in the Bay of Brest and pumping from a bay in the Shetland Islands to an inland IFC; and several drone deployments, both of Unmanned Aerial Vehicles (UAV) and of Autonomous Surface vehicles (ASVs). Additionally, we have reviewed sampling approaches potentially relevant for HAB early warning including protocols for opportunistic water sampling by coastguard agencies. Experiences in the determination of marine biotoxins in non-traditional vectors and how they could complement standard routine HAB monitoring are also considered

Where, when and why: modelling the distribution and habitat of deep-diving cetaceans incorporating variables depicting the deep oceanic layers

The use of Species Distribution Models (SDMs) has increased considerably in recent decades, notably for conservation purposes. SDMs are used particularly to characterise and predict marine top predator distributions thanks to the use of surface dynamic environmental variables (easily accessible and available at various spatial and temporal scales) as proxies for prey distribution. For oceanic species that spend most of their time in depth waters like deep-diving cetaceans (here beaked whales and sperm whales), the use of surface variables may limit the ability to correctly infer their habitats through SDMs. We combine, static variables that characterise the topography of the bottom water and dynamic variables integrated over different depth classes that characterise the water column into Generalised Additive Models to model the distribution of deep-diving cetaceans in the Bay of Biscay and to identify which variables are the most important for each species. We obtained relationships with the environment that allow predicting the highest densities of beaked whales and sperm whales near the continental slope, near canyons and seamounts and in the abyssal plain of the Bay of Biscay. We also identified different responses between beaked whales, for which surface, subsurface and static variables were selected as the most important variables, and sperm whales. For the latter only surface and depth variables were selected, which could suggest differences in foraging strategies and in the prey targeted between these species. The continuous development of ocean models and the availability of depth variables, allows as we have shown, the improvement of the tools available for the planning of human activities, especially for species that would be closely linked to processes taking place in deep waters, such as top predators

DIVERSIMAR Project: marine citizen science in the North and Northwest Iberian coast

Marine citizen science can play an important role in understanding the ocean responses to global change and other pressures to marine systems. Citizen science projects guide public participation combining research with environmental education and science divulgation [1, 4]. The DIVERSIMAR project (https://diversimar.cesga.es/) aims to register biodiversity data of the North and Northwest Iberian coast and is a way for science and society to interact and collaborate [3]. A system to integrate both the available scientific information (on distribution, biology and ecology of marine species) and the new information provided by volunteers has been designed. In a first step, volunteers contact directly the scientists providing photos, videos and any other information about their findings. Technological innovations such as smartphone devices equipped with cameras become a powerful tool for data collection because the images have associated metadata such as date and position [2]. In a second step, these records are verified, validated and stored in the project GIS database that can be consulted in the DIVERSIMAR Map Viewer (https://diversimar.cesga.es/visor/index.php). Different stakeholders, from scientists to citizens, and from fishermen to marine environmental organisations, can get involved in this citizen project. The wide-ranging observations on coastal flora and fauna (such as the occurrence and regularity of jellyfish blooms, the sporadic report of species that have never been observed in a region before, the apparition of invasive species, the presence of kelp forests or the sighting of protected species) allow to increase the temporal and spatial data acquisition and play an important role in monitoring the coastline and the intertidal zones. The information gathered by mapping habitats and by determination of abundance and distribution of native and invasive species demonstrate the scientific value of citizen monitoring to help managers to develop management plans and conservation strategies such as EU Marine Strategy framework Directive.Fundación Biodiversida