In metacommunity theory, which has primarily addressed horizontal processes, vertical connectivity has received little attention despite being a primary driver of biodiversity in spatially structured environments. This conceptual blind spot limits our understanding of community assembly in marine environments, where vertical processes are fundamental. Here, we used marine cave sessile communities as a model system to develop and test the first mechanistic framework to explicitly incorporate vertical connectivity, which we applied across hierarchical spatial scales. Based on a two-year dataset including nine marine caves in the Canary Islands, we partitioned community variance, examined spatial patterns of beta diversity, and analysed autocorrelation. Three-dimensional bathymetric analysis quantified connectivity to deep-water habitats, and mixed-effects models tested its influence on community diversity and thermal affinities. Cave-scale variance exceeded island-scale variance, a pattern consistent with a pronounced “cave individuality”. Species turnover drove beta diversity, and distance decay was weak — a pattern inconsistent with horizontal dispersal models. Bathymetric connectivity was a key predictor of diversity: caves more connected to deep-water habitats supported richer assemblages. These patterns reflect shifts in thermal structure, with well-connected caves exhibiting greater thermal diversity and stronger cold-water affinities. We propose the Environmental Patch Dynamics (EPD) framework, a mechanistic extension of metacommunity theory integrating species sorting and patch dynamics across four hierarchical stages. Vertical recruitment from depth-stratified external propagule pools, mediated by episodic upwelling, primarily structures these communities. By incorporating vertical connectivity and benthic–pelagic coupling, the EPD framework provides a transferable architecture for understanding community assembly in other vertically-structured ecosystems and reveals clear implications for their conservation under a warming ocean.

In the context of ocean warming, thermophilic organisms such as zoantharians are becoming increasingly widespread worldwide. Zoantharians exhibit high resistance to habitat degradation and environmental change, which has led to a growing research interest in this group. These organisms thrive in intertidal habitats of Tenerife (Canary Islands), an environment particularly vulnerable to metal contamination due to its proximity to the coast, where anthropogenic pressures are concentrated. Thus, this study aimed to evaluate metal concentrations in three intertidal zoantharian species (Palythoa aff. clavata, Zoanthus pulchellus and Isaurus tuberculatus) across different locations in Tenerife, representing the first ecotoxicological assessment in zoantharians. The three species showed high metal concentrations, demonstrating their capacity to bioaccumulate metals. Results indicated that Z. pulchellus and P. aff. clavata accumulated higher levels of most metals compared to I. tuberculatus, likely reflecting differences in feeding strategies and dependence on photosynthesis. Metal bioaccumulation levels of Z. pulchellus and P. aff. clavata, particularly in relation to Fe and Al, suggest their potential use as bioindicators of metal pollution in intertidal environments should be further investigated. Overall, these results enhance our understanding of metal exposure in intertidal habitats and support the inclusion of intertidal zoantharians as sentinels of coastal ecotoxicological monitoring studies.

Submarine volcanic eruptions are strong pulse disturbances that can cause abrupt mortality and long-lasting changes in marine communities. In October 2011, a submarine eruption off El Hierro (Canary Islands, Spain) generated a sulphurous plume that affected the Punta de La Restinga-Mar de Las Calmas Marine Reserve and surrounding coastal areas. Using a 25-year time series of fish community data, we assessed post-disturbance trajectories of commercial species across different protection levels within the impacted region. Resilience was analyzed as a sequential process, partitioned into resistance (initial biomass loss), recovery trajectory (temporal trend after the disturbance), and relative recovery compared with pre-eruption conditions. Because all sites were affected by the volcanic plume, our inference is restricted to comparative differences among protection categories rather than to the absolute effectiveness of protection. The no-take zone showed higher relative resistance and faster positive trajectories in total fish biomass than less-protected areas, indicating more favorable post-disturbance dynamics. However, eight years after the eruption, community structure had not fully returned to pre-eruption conditions in any protection level, reflecting contrasting recovery times among species with different life histories. Fast-growing species such as the parrotfish Sparisoma cretense recovered rapidly, whereas long-lived predators such as Epinephelus marginatus remained below their pre-disturbance biomass. Our results provide a long-term, community-level comparison of post-volcanic recovery within a marine reserve and highlight how protection status is associated with differences in recovery dynamics under a rare natural disturbance.

Ocean warming in subtropical waters of the Canary Islands is promoting the proliferation of thermophilic organisms, including zoantharians, which now dominate some shallow rocky reefs and induce community-level changes through their mat-forming growth. Advanced methodologies, such as photogrammetry, enable precise monitoring of spatiotemporal changes and population dynamics in sessile benthic species. In this study, a Palythoa caribaeorum-dominated area in Tenerife Island was surveyed biannually over 2 yr using structure-from-motion photogrammetry. Seasonal variations in benthic community coverages, P. caribaeorum growth rates, and zoantharian-algae interactions were assessed. Colony growth exhibited a strong correlation with seawater temperature, showing a significant coverage expansion during warm seasons (0.43 ± 0.33 cm2/month) and contraction during colder periods (− 0.36 ± 0.29 to − 0.49 ± 0.44 cm2/month). The 2nd year, which was 1.03 °C warmer on average, exhibited enhanced colony growth during the warm season, resulting in a 15.14

Marinas, as other maritime transport hubs, act as reservoirs for the introduction and secondary spread of non-indigenous bryozoans, which are key components of fouling communities. Although understanding habitat use patterns of these organisms could be very useful for implementing management strategies, the ecology of bryozoans in marinas has been greatly overlooked. To explore this issue, we sampled a total of 12 marinas on four islands of the Canarian archipelago (North-Eastern Atlantic). The occurrence of bryozoans (both total species and non-indigenous ones) was compared in contrasting zones within the marinas (i.e. interior and exterior) and types of floating artificial substrates (i.e. floating pontoons, buoys and ropes). We recorded a total of 23 bryozoan species, including 12 non-indigenous species. Both the type of substrate and the singularity of the marinas were the main factors driving the structure of bryozoan assemblages in marinas of the Canary Islands, while the sampled island had only a very subtle influence. Buoys showed the highest number of total and non-indigenous species of bryozoans, with some being registered only on this substrate. This finding supports buoys as a priority substrate in strategies for monitoring and detecting non-indigenous bryozoans in marinas.

Ocean warming is facilitating the proliferation of zoantharians worldwide due to their thermophilic affinities. However, other anthropogenic factors, such as declining water quality, have been appointed to favour the occurrence of zoantharians dominated areas and barrens. Subtropical and tropical intertidal habitats are especially vulnerable to zoantharians outbreaks due to the progressive increase in ocean temperature and because it is where most human pressure is concentrated. The aim of this study was to evaluate the abundance of intertidal zoantharians populations, related to habitat characteristics (rugosity and submerged substrate) and the presence of other benthic organisms, such as sessile invertebrates and macroalgae. Number and coverage of zoantharian colonies were recorded in transects (20 x 4m) along 25 intertidal rocky platforms of the Canarian Archipelago, and photographic techniques in quadrats were used to examine the relationships between the percentage of substrate cover of zoantharians, macroalgae and sessile invertebrates by means of correlations analyses. Results indicated that high levels of rugosity favour the abundance and coverage of Palythoa aff. clavata and Zoanthus pulchellus, and the proportion of submerged substrate was also important in determining Zoanthus coverages. The presence of extensive macroalgae communities was seen to reduce zoantharian coverages, being the only sessile organisms that were able to outcompete them for space in the Canary Islands. Thus, this study provided valuable information about patterns of abundances and coverages of intertidal zoantharians useful for future monitoring of intertidal populations of zoantharians in Canary Islands and their interaction with surrounding marine organisms.

This study presents a novel approach to high-resolution density distribution mapping of two key species of the 1170 “Reefs” habitat, Dendrophyllia cornigera and Phakellia ventilabrum, in the Bay of Biscay using deep learning models. The main objective of this study was to establish a pipeline based on deep learning models to extract species density data from raw images obtained by a remotely operated towed vehicle (ROTV). Different object detection models were evaluated and compared in various shelf zones at the head of submarine canyon systems using metrics such as precision, recall, and F1 score. The best-performing model, YOLOv8, was selected for generating density maps of the two species at a high spatial resolution. The study also generated synthetic images to augment the training data and assess the generalization capacity of the models. The proposed approach provides a cost-effective and non-invasive method for monitoring and assessing the status of these important reef-building species and their habitats. The results have important implications for the management and protection of the 1170 habitat in Spain and other marine ecosystems worldwide. These results highlight the potential of deep learning to improve efficiency and accuracy in monitoring vulnerable marine ecosystems, allowing informed decisions to be made that can have a positive impact on marine conservation.

The future of marine ecosystems is at risk due to climate change and other human impacts. Specifically, due to ocean warming, some tropical species are expanding their populations while populations of temperate species are in regression, making the establishment of conservation measures imperative to maintain local biodiversity. In this study we establish a baseline on the distribution and abundance of the temperate coral Balanophyllia regia from the Canary Islands. We found that the main environmental factors determining B. regia’s distribution and abundance were sea surface temperature and hydrodynamic conditions. Areas under large wave action and colder environments enhanced this warm-temperate species’ development. Since its metabolic performance depends exclusively on the surrounding environment, we also propose a methodology to potentially monitor climate change on coastal habitats through this azooxanthellate calcified coral. Results of a tagging experiment showed that a concentration of 20 mg/mL of calcein during 6 h might be enough to in situ label polyps of B. regia without compromising corallite survival. Long-term monitoring of population abundances and growth rates of B. regia through calcein tagging will allow us to identify alterations in local ecosystems early and focus future conservation investments on the most vulnerable areas with higher ecological and economic value.

Population outbreaks of zoantharians in shallow water reefs have been observed globally, including intertidal and subtidal sites in the Canary Islands. This study investigated how zoantharians might be integrating into the local trophic network. For that purpose, we assessed the feeding patterns of common species in zoantharian-dominated habitats, focusing on finding consumers of Zoanthus pulchellus and Palythoa caribaeorum. Through DNA-barcoding and metabarcoding, the gut contents of 11 predatory species were analysed, aiming to characterize their diets and explore local species feeding on zoantharians. Analyses of diet revealed a diverse range of food items and trophic positions of some of the most common and frequent marine species in the archipelago. Furthermore, based on previous observations on the different impacts of Z. pulchellus and P. caribaeorum on shallow benthic ecosystems of the Canary Islands, a preliminary approach to identify their potential influence on feeding patterns of associated species was made. Even though DNA-metabarcoding did not detect zoantharians in the gut contents of any studied species, Sanger sequencing with zoantharian-specific primers indicated their consumption by subject species may be limited to only the crab Platypodiella picta. In addition, by focusing on some of the most common species, this study enhances our understanding of the local trophic network and provides an insight into trophic dynamics in zoantharian-dominated habitats.

Early life stages of fish are insufficiently studied in most regions around the globe, and consequently, there is an important gap in knowledge on the life cycle of most teleosts. In the Canary Islands (Eastern Central Atlantic), most studies on ichthyoplankton communities are based on traditional net tows in open waters that provide information about early larval stages of pelagic species in the area, while nearshore benthic fish remain highly understudied. In this study, light traps were employed for the first time to assess post-larval stages of neritic fish in this archipelago. A two-year survey was carried out to collect nearshore fish larvae every 6 months at 11 localities from El Hierro, Tenerife and Lanzarote. A total of 3940 fish larvae classified into 13 orders, 28 families and 44 species were collected. These results provide a wide description of the composition of the inshore ichthyoplankton off the Canary Islands, across islands and seasons. Main environmental factors (SST, sea floor orography, oceanographic phenomena …) influencing the population dynamics of this community are discussed. Additionally, the ichthyoplankton assemblages were assessed from the intra-annual perspective, analyzing the species composition and abundances by months and seasons, and providing new insights into reproduction cycles of many common benthic fishes at shallow marine ecosystems of the islands. This study is important to further understand the life cycles of some of the most common fish species in the Canary Islands, unraveling main environmental factors that affect the success of their offspring that sustain populations.

In the context of ocean warming, thermophilic organisms such as zoantharians are expanding and altering shallow benthic habitats. Here, a four-month laboratory experiment was performed to examine the influence of three types of macroalgae morphotypes common in the Canary Islands (turf algae, Lobophora spp., and crustose coralline algae) on the growth of two zoantharian species, Palythoa caribaeorum and Zoanthus pulchellus. Additionally, the grazing effects of echinoids Diadema africanum and Paracentrotus lividus were assessed as facilitators of substrate colonization by means of controlling macroalgae cover. Colony and algal coverages were measured at the beginning, middle and end of the experiment, and increments were calculated. Results indicated a general decrease in zoantharian colony sizes in contact with different algal types in the absence of sea urchins. However, P. caribaeorum colonies showed significant growth in the presence of D. africanum, highlighting the ecological importance of sea urchins in zoantharian population proliferation and subsequent community modification. This study represents the first investigation into zoantharian-macroalgae interactions under controlled conditions.

Microplastic pollution has an extremely widespread distribution, to the extent that microplastics could be ingested by aquatic organisms, including species of commercial importance for fisheries and aquaculture. In this work, the anthropogenic particles content of the gastrointestinal tracts of 86 individuals of cultivated European sea bass (Dicentrarchus labrax, n = 45) and gilt-head sea bream (Sparus aurata, n = 41) from Tenerife (Canary Islands, Spain) was determined. Samples were bought at local markets and directly transported to the laboratory. After the dissection of the fishes and digestion of the gastrointestinal tracts in 10% KOH (w/v) at 60 °C for 24 h, the digests were filtered (50 µm stainless-steel mesh) and visualized under a stereomicroscope, finding that most of the items were colourless (47.7% for Dicentrarchus labrax and 60.9% for Sparus aurata) and blue (35.3% vs. 24.8%) microfibers, with an average length of 1957 ± 1699 µm and 1988 ± 1853 µm, respectively. Moreover, 15.3% of the microfibres were analysed by Fourier transform infrared spectroscopy, showing the prevalence of cellulosic fibres together with polyester, polyacrylonitrile, and poly(ether-urethane). This pattern (microplastics shapes, colours, sizes, and composition) clearly agrees with previous studies carried out in the Canary Islands region regarding the determination of microplastics in the marine environment.

Proliferations of zoantharians along tropical and subtropical regions are increasingly common and usually associated with anthropogenic impacts and ecosystem degradation. In the Canary Islands, we studied how the dominance in the substrate of Palythoa caribaeorum and Zoanthus pulchellus affected fish communities. For that purpose, we recorded the composition and biodiversity of fish assemblages associated to both zoantharian and macroalgae dominated habitats. In general terms, we found significant reductions of total fish abundance and richness at P. caribaeorum dominated habitats compared with macroalgae stands. However, in terms of trophic structure, there were significant changes within both zoantharian habitats depending on their coverages of the substrate. Herbivores and small invertebrate feeders, which are more adapted to forage in the macroalgae canopy, were less abundant in zoantharian habitats. This study demonstrates that the increasing dominance of zoantharians throughout the archipelago restructure the ecosystems and impact the native fish communities, that may offer a positive feedback for invasive tropical species to thrive.

In the current context of climate change, benthic cnidarians of the genus Palythoa have been suggested to be resistant owing to their intrinsic biological characteristics. In tropical regions, some species are currently proliferating in areas where environmental conditions are less suitable for other organisms, even replacing hard coral ecosystems. Considering their tropical affinities, phase-shifts towards Palythoa-dominated areas could become more frequent in future climate change scenarios, leading to changes in ecosystem organization. The aim of this study was to evaluate the effect of climate change stressors in two common Palythoa spp. with different habitat affinities within a subtropical region, and the effect upon their predator-prey interactions. The results of this experimental study demonstrated that colonies of P. aff. clavata and P. caribaeorum were significantly affected by exposure to temperature and pH conditions predicted for 2100 in the Canary Islands, during 62 days. Despite zoantharians' lack of carbonate in their body wall, Palythoa spp. were most affected in their growth rates by lowered pH, and colonies significantly decreased in weight and size. Although all colonies exhibited symptoms of bleaching at high temperature, a reduction in chlorophyll content was also observed at low pH. Predation by Platypodiella picta crabs decreased on P. aff. clavata exposed to acidic conditions, which may compensate for the lowered ecological performance of the species in these climate change conditions. In contrast, P. picta was able to actively feed on P. caribaeorum colonies regardless of the experimental conditions. Despite being suggested as winner species in a climate change scenario, our study demonstrated that low pH negatively impacted Palythoa spp. survival. If the species are not able to acclimatize to the new conditions, changes in their populations may be expected, although their magnitude could be ameliorated by means of a decrease in predation rates.

Modeling is a useful approach to learn about the capacity of the systems to recover after disturbances. In October 2011, a submarine volcanic eruption in The Punta Restinga-Mar de Las Calmas Marine Protected Area (RMC-MPA) caused catastrophic mass mortality. We modeled the recovery dynamics of the fully protected (no-take zone), partially protected (buffer zone), and unprotected (fished zone) areas to evaluate their resilience and their potential to restore fishing resources. Recovery varied with species and levels of protection. Benthic macroalgae and parrotfish populations recovered the fastest. Piscivore fishes, macroinvertebrate feeders, and macroinvertebrate detritivores required more extended recovery periods. The levels of protection played a significant role in recovery, with the no-take zone showing more resilience than the buffer and fished zones. Our results suggest that no-take zones are crucial in the recovery process after catastrophic events. Regular monitoring of benthic communities provided the necessary data to model these communities and to point to the regulation of the artisanal fleet activity in restricted fishing areas as a mechanism to further enhance the recovery of fishing stocks.

Diadema africanum is a recently described sea urchin from the Eastern Atlantic archipelagos, and adults play a major ecological role mediating the transition between two alternative ecosystem states: macroalgal beds and urchin barrens. The aim of this study was to describe for the first time the egg characteristics, fertilization and larval development. To determine basic life-history characteristics for this species, we reared larvae through to metamorphic competence under an energy shortage experiment and temperature-pH experiments to characterize the morphological plasticity of larval responses to actual and future oceanic conditions. D. africanum produces eggs that are larger both in diameter (82.7 mu m) and volume (0.30 nl) than the eggs of both Diadema antillarum (70.0 mu m, 0.18 nl) and Diadema mexicanum (68.0 mu m, 0.16 nl). Larval development is similar to other species within the Family Diadematidae, with a Echinofilutens transversus larval type morphology. The combined effects of the climate change-related environmental factors resulted in a reduction in fitness of D. africanum at the warmer limit of its thermal range when combined with low pH. Results suggest that the egg and larval life-history characteristics of D. africanum may have evolved to facilitate long-distance oceanic transport; however, near-future oceanic conditions may compromise larval survival.

Global warming is driving changes in the distribution patterns of many species, leading to a general tropicalization and meridionalization of biota. In this context, populations of some marine species are in regression while others are expanding their populations. Such is the case of benthic cnidarians belonging to the order Zoantharia and suborder Brachycnemina, whose populations are able to cause phase-shifts in coral reef ecosystems. Marine assemblages in the subtropical Canary Islands region consist of a combination of both temperate and tropical species, mainly due to the east-to-west seawater temperature gradient that naturally exists throughout the archipelago. This can reach a 2 degrees C difference (approximate to 23-25 degrees C east to west in summer months). These biogeographical features make the archipelago a unique location to research into biota reorganisation processes. The aim of this study was to establish a baseline of the distribution and abundance data of zoantharian Brachycnemina populations in the Canary Islands. To elucidate whether these species are potential bioindicators of ocean warming processes, patterns of species distribution and their relationships with the temperature gradient across the archipelago were also evaluated. Results demonstrated that intertidal and subtidal populations of Palythoa aff. clavata and P. caribaeorwn, respectively, followed distribution patterns related to the temperature ranges recorded in situ by data loggers. Extensive populations were found in the western islands where seawater temperatures are warmer than the eastern islands. Since biota reorganisation usually produces loss of ecosystem functions, it is essential to establish baseline datasets of climate change indicators and also effective monitoring programmes. These will allow early detection of phase-shifts before they lead to significant changes in ecosystem dynamics.

Estimating survival rate is a basic part of population studies. Generally it is assumed that populations being studied are both stable and stationary. This probably is seldom the case although as a long-term average populations may persist at a mean density. Estimating survival in short-term studies may fail to capture average rates. A long-term study of the purple sea urchin Strongylocentrotus purpuratus at Sunset Bay, OR, USA from 1964–2009 is used to demonstrate methods for estimating survival based on the coefficient of variation of size distributions, the fraction of new recruits in a population, means of size data coupled with estimates of growth, and a method that uses rates of flow through size categories. A short-term study of just a few years may by chance sample when an unusual recruitment event drives a population far from stationary structure and so distorts the estimate of mean survival. The best solution, as shown for S. purpuratus, is a long time series but in advance it cannot be determined how long this should be. If a study of three years shows no substantial change in population size structure it may be reasonable to accept estimates of survival.