Husbandry Protocols for Juvenile Loggerhead Sea Turtles (Caretta caretta) Based on Stress Response to Stocking Density and Dry-Dock Time.

When necessary, sea turtles are held captive for veterinarian care and research purposes. Protocols and basic guidelines have been described for husbandry of sea turtles with veterinarian needs but not considering physiological indicators of animal welfare. Because all sea turtle are imperiled species, monitoring their welfare is important. The aim of this study was to standardize husbandry protocols for loggerhead (Caretta caretta) juveniles held under seminatural conditions, based on circulating concentration of plasma corticosterone (Cort) and behavior. Two experiments were performed to analyze physiological and behavioral responses of the animals facing changes in stocking density and different dry-docking times. Cort analyses suggested that the number of animals per tank can be modified occasionally, without affecting their health and welfare. However, dry-docking time should be < 30 min, as indicated by the significant elevation of circulating Cort at ≥ 30 min, rising from 1.51- ng/ml to 5.28-ng/ml. Protocols tested did not affect behavioral responses, except for the breaths per move, which increased while Cort increased, despite differences exhibited by experimental animals in behavioral responses according to daily times (morning vs afternoon) and the sex of the animals.

Population Genomics Reveals the Underlying Structure of the Small Pelagic European Sardine and Suggests Low Connectivity within Macaronesia.

The European sardine (Sardina pilchardus, Walbaum 1792) is indisputably a commercially important species. Previous studies using uneven sampling or a limited number of makers have presented sometimes conflicting evidence of the genetic structure of S. pilchardus populations. Here, we show that whole genome data from 108 individuals from 16 sampling areas across 5000 km of the species' distribution range (from the Eastern Mediterranean to the archipelago of Azores) support at least three genetic clusters. One includes individuals from Azores and Madeira, with evidence of substructure separating these two archipelagos in the Atlantic. Another cluster broadly corresponds to the center of the distribution, including the sampling sites around Iberia, separated by the Almeria-Oran front from the third cluster that includes all of the Mediterranean samples, except those from the Alboran Sea. Individuals from the Canary Islands appear to belong to the Mediterranean cluster. This suggests at least two important geographical barriers to gene flow, even though these do not seem complete, with many individuals from around Iberia and the Mediterranean showing some patterns compatible with admixture with other genetic clusters. Genomic regions corresponding to the top outliers of genetic differentiation are located in areas of low recombination indicative that genetic architecture also has a role in shaping population structure. These regions include genes related to otolith formation, a calcium carbonate structure in the inner ear previously used to distinguish S. pilchardus populations. Our results provide a baseline for further characterization of physical and genetic barriers that divide European sardine populations, and information for transnational stock management of this highly exploited species towards sustainable fisheries.

Higher daily temperature range at depth is linked with higher thermotolerance in antipatharians from the canary islands.

Sensitivity to ocean warming is generally expected to be lower in populations from more heterogeneous thermal environments, owing to greater phenotypic plasticity and/or genotype selection. While resilience of benthic populations from thermally fluctuating environments has been investigated at a variety of spatial scales, this has received limited attention across depths and has remained unresolved for Antipatharian corals, key habitat-forming species across a wide bathymetric range in all of the world oceans. In this study, we aimed at addressing the thermal sensitivity of Antipatharian corals across depths characterized by different levels of temperature fluctuations. We used an acute ramping experimental approach to compare the thermal sensitivity of colonies of (1) the branched Antipatharian Antipathella wollastoni (Gray, 1857) from two distinct depths (25 and 40 m) in Gran Canaria (Canary Islands, Spain); and of (2) unbranched mesophotic (80 m) Stichopathes species, from Lanzarote (Canary Islands, Spain; S. gracilis (Gray, 1857)), and Stichopathes sp. clade C from Mo'orea, French Polynesia. Results showed that the daily temperature range in Gran Canaria was larger at mesophotic depths (3.9 °C vs. 2.8 °C at 40 and 25 m, respectively) and this coincided with lower thermal sensitivity in mesophotic colonies of A. wollastoni. Second, S. gracilis from Lanzarote showed a lower thermal sensitivity than the previously studied Stichopathes sp. clade C from Mo'orea (French Polynesia) inhabiting a less variable habitat. These results are in line with the climate variability hypothesis, which states that populations under more variable thermal conditions have a lower sensitivity to warming than those from more stable environments, as they have adapted/acclimated to these higher levels of temperature fluctuations.

Levelling-up rhodolith-bed science to address global-scale conservation challenges.

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.

Black coral forests enhance taxonomic and functional distinctiveness of mesophotic fishes in an oceanic island: implications for biodiversity conservation.

The degradation of shallow ecosystems has called for efforts to understand the biodiversity and functioning of Mesophotic Ecosystems. However, most empirical studies have been restricted to tropical regions and have majorly focused on taxonomic entities (i.e., species), neglecting important dimensions of biodiversity that influence community assembly and ecosystem functioning. Here, using a subtropical oceanic island in the eastern Atlantic Ocean (Lanzarote, Canary Islands), we investigated variation in (a) alpha and (b) beta functional (i.e., trait) diversity across a depth gradient (0-70 m), as a function of the presence of black coral forests (BCFs, order Antipatharian) in the mesophotic strata, a vulnerable but often overlooked 'ecosystem engineer' in regional biodiversity. Despite occupying a similar volume of the functional space (i.e., functional richness) than shallow (< 30 m) reefs, mesophotic fish assemblages inhabiting BCFs differed in their functional structure when accounting for species abundances, with lower evenness and divergence. Similarly, although mesophotic BCFs shared, on average, 90% of the functional entities with shallow reefs, the identity of common and dominant taxonomic and functional entities shifted. Our results suggest BCFs promoted the specialization of reef fishes, likely linked to convergence towards optimal traits to maximize the use of resources and space. Regional biodiversity planning should thus focus on developing specific management and conservation strategies for preserving the unique biodiversity and functionality of mesophotic BCFs.

Drivers of variation in seagrass-associated amphipods across biogeographical areas.

Amphipods are one of the dominant epifaunal groups in seagrass meadows. However, our understanding of the biogeographical patterns in the distribution of these small crustaceans is limited. In this study, we investigated such patterns and the potential drivers in twelve Cymodocea nodosa meadows within four distinctive biogeographical areas across 2000 Km and 13° of latitude in two ocean basins (Mediterranean Sea and Atlantic Ocean). We found that species abundances in the assemblage of seagrass-associated amphipods differed among areas following a pattern largely explained by seagrass leaf area and epiphyte biomass, while the variation pattern in species presence/absence was determined by seagrass density and epiphyte biomass. Seagrass leaf area was also the most important determinant of greater amphipod total density and species richness, while amphipod density also increased with algal cover. Overall, our results evidenced that biogeographical patterns of variation in amphipod assemblages are mainly influenced by components of the habitat structure, which covary with environmental conditions, finding that structurally more complex meadows harboring higher abundance and richness of amphipods associated.

Mapping and assessing seagrass meadows changes and blue carbon under past, current, and future scenarios.

Seagrasses store large amounts of blue carbon and mitigate climate change, but they have suffered strong regressions worldwide in recent decades. Blue carbon assessments may support their conservation. However, existing blue carbon maps are still scarce and focused on certain seagrass species, such as the iconic genus Posidonia, and intertidal and very shallow seagrasses (<10 m depth), while deep-water and opportunistic seagrasses have remained understudied. This study filled this gap by mapping and assessing blue carbon storage and sequestration by the seagrass Cymodocea nodosa in the Canarian archipelago using the local carbon storage capacity and high spatial resolution (20 m/pixel) seagrass distribution maps for the years 2000 and 2018. Particularly, we mapped and assessed the past, current and future capacity of C. nodosa to store blue carbon, according to four plausible future scenarios, and valued the economic implications of these scenarios. Our results showed that C. nodosa has suffered ca. 50 % area loss in the last two decades, and, if the current degradation rate continues, our estimations demonstrate that it could completely disappear in 2036 ("Collapse scenario"). The impact of these losses in 2050 would reach 1.43 MT of CO2 equivalent emitted with a cost of 126.3 million € (0.32 % of the current Canary GDP). If, however, this degradation is slow down, between 0.11 and 0.57 MT of CO2 equivalent would be emitted until 2050 ("Intermediate" and "Business-as-usual" scenarios, respectively), which corresponds to a social cost of 3.63 and 44.81 million €, respectively. If the current seagrass extension is maintained ("No Net Loss"), 0.75 MT of CO2 equivalent would be sequestered from now to 2050, which corresponds to a social cost saving of 73.59 million €. The reproducibility of our methodology across coastal ecosystems underpinned by marine vegetation provides a key tool for decision-making and conservation of these habitats.

Habitat configurations shape the trophic and energetic dynamics of reef fishes in a tropical-temperate transition zone: implications under a warming future.

Understanding the extent to which species' traits mediate patterns of community assembly is key to predict the effect of natural and anthropogenic disturbances on ecosystem functioning. Here, we apply a trait-based community assembly framework to understand how four different habitat configurations (kelp forests, Sargassum spp. beds, hard corals, and turfs) shape the trophic and energetic dynamics of reef fish assemblages in a tropical-temperate transition zone. Specifically, we tested (i) the degree of trait divergence and convergence in each habitat, (ii) which traits explained variation in species' abundances, and (iii) differences in standing biomass (kg ha-1), secondary productivity (kg ha-1 day-1) and turnover (% day-1). Fish assemblages in coral and kelp habitats displayed greater evidence of trait convergence, while turf and Sargassum spp. habitats displayed a higher degree of trait divergence, a pattern that was mostly driven by traits related to resource use and thermal affinity. This filtering effect had an imprint on the trophic and energetic dynamics of reef fishes, with turf habitats supporting higher fish biomass and productivity. However, these gains were strongly dependent on trophic guild, with herbivores/detritivores disproportionately contributing to among-habitat differences. Despite these perceived overall gains, turnover was decoupled for fishes that act as conduit of energy to higher trophic levels (i.e. microinvertivores), with coral habitats displaying higher rates of fish biomass replenishment than turf despite their lower productivity. This has important implications for biodiversity conservation and fisheries management, questioning the long-term sustainability of ecological processes and fisheries yields in increasingly altered marine habitats.

Playing hide and seek: Distribution with depth of potentially harmful epibenthic dinoflagellates of Southern El Hierro Island, Canary Islands (NE Atlantic).

The study of epibenthic assemblages of harmful dinoflagellates (BHABs) is commonly conducted in shallow infralittoral zones (0 - 5 m) and are seldom investigated at deeper waters. In this study, the distribution with depth of five BHAB genera (Gambierdiscus, Ostreopsis, Prorocentrum, Coolia and Amphidinium) was investigated in the south of El Hierro island (Canary Islands, Spain). Sampling involved the use of a standardized artificial substrate deployed at three depth levels (5, 10 and 20 m) that were visited at three different times throughout one year. The influence of three depth-correlated abiotic parameters, i.e. light, water motion and water temperature, on the vertical and seasonal distribution of the BHAB assemblage was also assessed. Two vertical distribution patterns were observed consistently through time: cell abundances of Ostreopsis and Coolia decreased from 5 to 20 m while those of Gambierdiscus, Prorocentrum and Amphidinium showed the reverse pattern, although significant differences were only observed between 5 and 10 - 20 m depth. In April, two members of the latter group, Gambierdiscus and Amphidinium, were even absent at 5 m depth. The recorded environmental parameters explained a high percentage of the observed distribution. In particular, model selection statistical approaches indicated that water motion was the most significant parameter. An analysis of Gambierdiscus at species level revealed the co-occurrence of four species in the study area: G. australes, G. belizeanus, G. caribaeus and G. excentricus. The species G. excentricus, reported here for the first time in El Hierro, showed a more restricted vertical and seasonal distribution than the other species, which may explain not being detected in previous studies in the area. The results obtained in this study highlight the importance of considering a wider depth range and different seasons of the year when investigating the ecology of BHABs and assessing their risk and impacts on human health and the environment. Only then, efficient monitoring programs will be implemented in the Canary Islands and globally in areas affected by these events.

Distribution and population structure of the smooth-hound shark, Mustelus mustelus (Linnaeus, 1758), across an oceanic archipelago: Combining several data sources to promote conservation.

Sharks play a key role in the structure and functioning of marine ecosystems. More ecological information is essential to implement responsible management and conservation actions on this fauna, particularly at a regional level for threatened species. Mustelus mustelus is widely found in the eastern Atlantic Ocean and catalogued as "Vulnerable" by the IUCN European assessment. In this study, data on the distribution and population structure of this species across the islands of the Canarian archipelago, located along an east to west gradient in the north-eastern Atlantic, were collected by taking advantage of "Local Ecological Knowledge," in terms of sightings in coastal waters and long-term imprints on the local gastronomic heritage, and decadal fisheries landings. Both sources of quantitative data (sightings and fisheries landings) demonstrated that adults of M. mustelus has a significantly larger presence in the eastern and central, than in the western islands of the archipelago. This is also reflected on local gastronomic legacies, with a larger number of recipes in the eastern and central islands. Adult smooth-hound sharks were significantly more observed in sandy and sandy-rocky bottoms, with individuals seen throughout the entire year, whereas juveniles aggregate on very shallow waters in spring and summer. Such aggregations require a special management strategy, as they play a key role in critical life stages; these sites should be protected from human perturbations. We also suggest a temporal fishing ban between April and October, when individuals tend to concentrate on nearshore waters. Because of the large differences in presence of this shark among the Canary Islands, management of the species should be adapted to the specific peculiarities of each island, rather than adopting a management policy at the entire archipelago-scale. Overall, this study sets the basis for further investigation to promote conservation of this vulnerable shark in the study region.

Persistent thermally driven shift in the functional trait structure of herbivorous fishes: Evidence of top-down control on the rebound potential of temperate seaweed forests?

Extreme climatic events can reshape the functional structure of ecological communities, potentially altering ecological interactions and ecosystem functioning. While these shifts have been widely documented, evidence of their persistence and potential flow-on effects on ecosystem structure following relaxation of extreme events remains limited. Here, we investigate changes in the functional trait structure - encompassing dimensions of resource use, thermal affinity, and body size - of herbivorous fishes in a temperate reef system that experienced an extreme marine heatwave (MHW) and subsequent return to cool conditions. We quantify how changes in the trait structure modified the nature and intensity of herbivory-related functions (macroalgae, turf, and sediment removal), and explored the potential flow-on effects on the recovery dynamics of macroalgal foundation species. The trait structure of the herbivorous fish assemblage shifted as a result of the MHW, from dominance of cool-water browsing species to increased evenness in the distribution of abundance among temperate and tropical guilds supporting novel herbivory roles (i.e. scraping, cropping, and sediment sucking). Despite the abundance of tropical herbivorous fishes and intensity of herbivory-related functions declined following a period of cooling after the MHW, the underlying trait structure displayed limited recovery. Concomitantly, algal assemblages displayed a lack of recovery of the formerly dominant foundational species, the kelp Ecklonia radiata, transitioning to an alternative state dominated by turf and Sargassum spp. Our study demonstrates a legacy effect of an extreme MHW and exemplified the value of monitoring phenotypic (trait mediated) changes in the nature of core ecosystem processes to predict and adapt to the future configurations of changing reef ecosystems.

Leveraging the blue economy to transform marine forest restoration.

The UN Decade of Ecosystem Restoration is a response to the urgent need to substantially accelerate and upscale ecological restoration to secure Earth's sustainable future. Globally, restoration commitments have focused overwhelmingly on terrestrial forests. In contrast, despite a strong value proposition, efforts to restore seaweed forests lag far behind other major ecosystems and continue to be dominated by small-scale, short-term academic experiments. However, seaweed forest restoration can match the scale of damage and threat if moved from academia into the hands of community groups, industry, and restoration practitioners. Connecting two rapidly growing sectors in the Blue Economy-seaweed cultivation and the restoration industry-can transform marine forest restoration into a commercial-scale enterprise that can make a significant contribution to global restoration efforts.

Differences in the occurrence and abundance of batoids across an oceanic archipelago using complementary data sources: Implications for conservation.

Batoids, distributed from shallow to abyssal depths, are considerably vulnerable to anthropogenic threats. Data deficiencies on the distribution patterns of batoids, however, challenge their effective management and conservation. In this study, we took advantage of the particular geological and geomorphological configuration of the Canary Islands, across an east-to-west gradient in the eastern Atlantic Ocean, to assess whether patterns in the occurrence and abundance of batoids varied between groups of islands (western, central, and eastern). Data were collected from shallow (<40 m, via underwater visual counts and by a local community science program) and deep waters (60-700 m, via ROV deployments). Eleven species of batoids, assessed by the IUCN Red List of Threatened Species, were registered, including three "Critically Endangered" (Aetomylaeus bovinus, Dipturus batis, and Myliobatis aquila), three "Endangered" (Gymnura altavela, Mobula mobular, and Rostroraja alba), two "Vulnerable" (Dasyatis pastinaca and Raja maderenseis), and two "Data Deficient" (Taeniurops grabata and Torpedo marmorata). Also, a "Least Concern" species (Bathytoshia lata) was observed. Overall, batoids were ~1 to 2 orders of magnitude more abundant in the central and eastern islands, relative to the western islands. This pattern was consistent among the three sources of data and for both shallow and deep waters. This study, therefore, shows differences in the abundance of batoids across an oceanic archipelago, likely related to varying insular shelf area, availability of habitats, and proximity to the nearby continental (African) mass. Large variation in population abundances among islands suggests that "whole" archipelago management strategies are unlikely to provide adequate conservation. Instead, management plans should be adjusted individually per island and complemented with focused research to fill data gaps on the spatial use and movements of these iconic species.

Assessment of captive rearing conditions on loggerhead hatchlings: Effect of handling frequency and stocking density.

Frequently, stranded sea turtles require rehabilitation under controlled conditions. Currently, few publications have described the conditions under which rehabilitation is to take place, particularly with respect to the hatchling life stage. To address this paucity of data, we conducted some experiments to assist rehabilitating facilities assess their handling of hatchlings. While in captivity, hatchlings are routinely handled, for example, for data collection and cleaning. Standardization of handling and housing protocols is necessary to define the most adequate rearing conditions to maintain hatchling welfare. Accordingly, the aim of this study was to assess plasma circulating corticosterone (Cort) concentration and growth, as a biomarker for the stress of hatchling loggerhead sea turtles (Caretta caretta) under controlled conditions. We performed two experiments to analyze handling frequency and stocking density. In both, Cort was measured and correlated with variations in animal weight and length. In handling experiments, Cort exhibited no significant increase when hatchlings were handled once a week, whereas Cort was significantly elevated when hatchlings were handled once every 2 weeks, suggesting that hatchlings have the ability to acclimate to frequent handling. However, hatchlings exhibited similar growth and mortality, regardless of handling regime. In stocking density experiments, hatchling isolation induced a significant elevation of Cort, in comparison with hatchlings placed with conspecifics at increasing densities. Growth increased in singly housed hatchlings, while mortality increased in tanks with three or more hatchlings. The results obtained suggest that Cort, growth, and mortality should be measured to assess hatchling welfare when kept under controlled conditions.

Partitioning resilience of a marine foundation species into resistance and recovery trajectories.

The resilience of an ecological unit encompasses resistance during adverse conditions and the capacity to recover. We adopted a 'resistance-recovery' framework to experimentally partition the resilience of a foundation species (the seagrass Cymodocea nodosa). The shoot abundances of nine seagrass meadows were followed before, during and after simulated light reduction conditions. We determined the significance of ecological, environmental and genetic drivers on seagrass resistance (% of shoots retained during the light deprivation treatments) and recovery (duration from the end of the perturbed state back to initial conditions). To identify whether seagrass recovery was linearly related to prior resistance, we then established the connection between trajectories of resistance and recovery. Finally, we assessed whether recovery patterns were affected by biological drivers (production of sexual products-seeds-and asexual propagation) at the meadow-scale. Resistance to shading significantly increased with the genetic diversity of the meadow and seagrass recovery was conditioned by initial resistance during shading. A threshold in resistance (here, at a ca. 70% of shoot abundances retained during the light deprivation treatments) denoted a critical point that considerably delays seagrass recovery if overpassed. Seed densities, but not rhizome elongation rates, were higher in meadows that exhibited large resistance and quick recovery, which correlated positively with meadow genetic diversity. Our results highlight the critical role of resistance to a disturbance for persistence of a marine foundation species. Estimation of critical trade-offs between seagrass resistance and recovery is a promising field of research to better manage impacts on seagrass meadows.

Driving factors of biogeographical variation in seagrass herbivory.

Despite the crucial role of herbivory in shaping community assembly, our understanding on biogeographical patterns of herbivory on seagrasses is limited compared to that on terrestrial plants. In particular, the drivers of such patterns remain largely unexplored. Here, we used a comparative-experimental approach in Cymodocea nodosa meadows, across all possible climate types within the seagrass distribution, 2000 km and 13° of latitude in two ocean basins, to investigate biogeographical variation in seagrass herbivory intensity and their drivers during July 2014. Particularly, the density and richness of herbivores and their food resources, seagrass size, carbon and nitrogen content, as well as latitude, sea surface temperature, salinity, chlorophyll, and sediment grain size, were tested as potential drivers. We found that shallow meadows can be subjected to intense herbivory, with variation in herbivory largely explained by fish density, seagrass size, and annual sea temperature range. The herbivorous fish density was the most important determinant of such variation, with the dominant seagrass consumer, the fish Sarpa salpa, absent at meadows from regions with low herbivory. In temperate regions where herbivorous fish are present, annual temperature ranges drive an intense summer herbivory, which is likely mediated not only by increased herbivore metabolic demands at higher temperatures, but also by higher fish densities. Invertebrate grazing (mainly by sea urchins, isopods, amphipods, and/or gastropods) was the dominant leaf herbivory in some temperate meadows, with grazing variation mainly influenced by seagrass shoot size. At the subtropical region (under reduced annual temperature range), lower shoot densities and seagrass nitrogen contents contributed to explain the almost null herbivory. We evidenced the combined influence of drivers acting at geographic (region) and local (meadow) scales, the understanding of which is critical for a clear prediction of variation in seagrass herbivory intensity across biogeographical regions.

Seagrass Cymodocea nodosa across biogeographical regions and times: Differences in abundance, meadow structure and sexual reproduction.

Seagrasses are key habitat-forming species of coastal areas. While previous research has demonstrated considerable small-scale variation in seagrass abundance and structure, studies teasing apart local from large-scale variation are scarce. We determined how different biogeographic scenarios, under varying environmental and genetic variation, explained variation in the abundance and structure (morphology and biomass allocation), epiphytes and sexual reproduction intensity of the seagrass Cymodocea nodosa. Regional and local-scale variation, including their temporal variability, contributed to differentially explain variation in seagrass attributes. Structural, in particular morphological, attributes of the seagrass leaf canopy, most evidenced regional seasonal variation. Allocation to belowground tissues was, however, mainly driven by local-scale variation. High seed densities were observed in meadows of large genetic diversity, indicative of sexual success, which likely resulted from the different evolutionary histories undergone by the seagrass at each region. Our results highlight that phenotypic plasticity to local and regional environments need to be considered to better manage and preserve seagrass meadows.

Benthic dinoflagellates: Testing the reliability of the artificial substrate method in the Macaronesian region.

The suitability of the 'artificial substrate' method, i.e. standardized surfaces of fiberglass screens, for the quantification of four benthic harmful algal bloom (BHAB) dinoflagellates (Gambierdiscus, Ostreopsis, Prorocentrum and Coolia) was tested relative to estimates from natural macroalgal substrates. Sampling took place in a variety of intertidal and subtidal coastal habitats under different water motion conditions, at depths from 1 to 7 m, in two archipelagos of the Macaronesia region: The Canary Islands and Cape Verde. An immersion time of 24 h was sufficient to adequately estimate dinoflagellate abundances. Seven replicates were established as the ideal replication level, considering both reproducibility and sampling effort. In most cases, cell abundances of the four dinoflagellate genera showed lower variability on artificial substrates than on macroalgae, leading to more reliable estimates of abundances. The ratio of mean cell abundances on artificial substrates to mean cell abundances on macroalgae highly varied among sampling sites for each genus. This was especially true for Ostreopsis and Coolia. Thus, given the potentially harmful nature of benthic dinoflagellates, the transformation of abundances expressed as cells g-1 of macroalgae to abundances expressed as cells cm-2 is risky, and it should not be attempted in monitoring and management programs of harmful microalgae. In summary, results of this study support the use of artificial substrates in monitoring programs of BHAB dinoflagellates, while the risks of using macroalgae are stressed.

Historical photographs of captures of recreational fishers indicate overexploitation of nearshore resources at an oceanic island.

In this study, we used a historical collection of photographs taken by recreational fishers from 1940 to 2014, at the island of Gran Canaria, to show both a significant decrease in the mean total length of Epinephelus marginatus and a concurrent change in the composition of captures. Before 1980, the mean total length of fish caught and photographed was c. 100 cm, while after 2009 this was typically < 40 cm. Before 1980, the predominant captured species was E. marginatus (an apex predator), but currently the majority of catches are of omnivorous species, in particular the parrotfish, Sparisoma cretense and seabreams Diplodus spp. Overall, integration of these results indicates a qualitative and quantitative variation in captures of recreational fishers, probably as a sign of change in ecological balances and the overfished status of many target species.

Genetic diversity and kelp forest vulnerability to climatic stress.

Genetic diversity confers adaptive capacity to populations under changing conditions but its role in mediating impacts of climate change remains unresolved for most ecosystems. This lack of knowledge is particularly acute for foundation species, where impacts may cascade throughout entire ecosystems. We combined population genetics with eco-physiological and ecological field experiments to explore relationships among latitudinal patterns in genetic diversity, physiology and resilience of a kelp ecosystem to climate stress. A subsequent 'natural experiment' illustrated the possible influence of latitudinal patterns of genetic diversity on ecosystem vulnerability to an extreme climatic perturbation (marine heatwave). There were strong relationships between physiological versatility, ecological resilience and genetic diversity of kelp forests across latitudes, and genetic diversity consistently outperformed other explanatory variables in contributing to the response of kelp forests to the marine heatwave. Population performance and vulnerability to a severe climatic event were thus strongly related to latitudinal patterns in genetic diversity, with the heatwave extirpating forests with low genetic diversity. Where foundation species control ecological structure and function, impacts of climatic stress can cascade through the ecosystem and, consequently, genetic diversity could contribute to ecosystem vulnerability to climate change.