Alejandro Pérez-Matus

In terrestrial environments, nest site selection by birds and mammals is often related to the physical attributes of surrounding vegetation. Similarly, some elasmobranchs use different habitats, including kelps, as oviposition sites. However, habitat features that drive oviposition site selection remain poorly understood. We examined the relationship between kelp morphology (holdfast diameter, number of stripes, and total length) and kelp forest configuration (density, size structure, predator density) with egg presence to identify the factors influencing oviposition choice in the redspotted catshark (Schroederichthys chilensis). We conducted surveys over a latitudinal gradient (19° S to 39° S), encompassing much of the overlap between the kelp, Lessonia trabeculata and S. chilensis in Chile. Eggs were exclusively attached between the upper stipe and basal fronds of Lessonia trabeculata in all sites. At the individual scale, S. chilensis selected larger kelps within a patch, independent of the general population size structure. The number of eggs and clutches was positively associated with stipe length and holdfast diameter. Across all sites, egg-bearing kelps were consistently clustered at a similar depth in the kelp forest rather than being randomly distributed. At the site scale, egg number had a negative correlation with their main predator abundance, Taliepus dentatus, and juvenile kelp density. These results suggest that S. chilensis shows low plasticity in substrate use, as evidenced by non-random, consistent oviposition in kelp morphology along a latitudinal gradient. Our results underscore the need to incorporate kelp size thresholds and the protection of egg-bearing aggregations into harvesting regulations, as overexploitation of L. trabeculata directly threatens the reproductive viability of S. chilensis.

Body size is a key functional trait linking individual physiology to ecological interactions and community structure. Size spectra provide a trait‐based framework to quantify how community size structure responds to environmental gradients, yet their large‐scale drivers remain poorly understood. We tested whether temperature and productivity differentially shape reef fish size structure, examining how sea surface temperature (SST) and chlorophyll‐ a (Chl‐ a ) influence size spectra and total biomass across a broad latitudinal gradient. Reef fish communities were consistently dominated by small‐bodied individuals, but cooler continental systems supported a higher proportion of medium to large fishes. Species richness declined with latitude, indicating strong biogeographic filtering across regions. Size‐spectrum exponents significantly differed among regions, reflecting shifts in the relative contribution of small versus large individuals. In contrast, variations in SST and Chl‐ a had no detectable effect on total biomass. Synthesis . The broad latitudinal patterns in these fish assemblages are governed primarily by shifts in community composition and size spectra, with SST exerting reduced effects, whereas total biomass shows limited variation across environmental gradients. This stresses the importance of conserving size structure—especially larger individuals—alongside biomass and supports management approaches that incorporate spatial ecoregional heterogeneity to safeguard size spectra at large geographic scales.

Physical disturbances, especially those that reduce or remove foundation species, have complex effects on ecosystem functioning. Evaluating resilience to predict these impacts requires long‐term research over large temporal and spatial scales. This study investigates the recovery of the subtidal kelp ( Lessonia trabeculata ) to simulated kelp harvesting in areas under different fisheries management regimes (Territorial Use Rights for Fisheries (TURF) vs. Open Access (OA) sites) along the Northern–Central Chilean coast. The managed TURF sites demonstrated significantly faster recovery of adult kelp densities following harvesting, while OA sites exhibited consistently lower kelp densities and delayed recovery. However, the generality of this pattern varied across regions. Morphological traits such as holdfast diameter were larger at TURF sites, where kelp exhibited larger size. Delayed size recovery was evidenced at OA sites. Herbivore densities were higher in OA than in TURF sites, potentially contributing to differences in kelp density, size and recovery. These patterns highlight the interaction between herbivory and management efficacy. Synthesis and applications . Our findings highlight the critical role of local fisheries management in enhancing kelp recovery after harvesting. The faster recovery of kelp at most TURF sites demonstrates how spatially explicit management can buffer ecological impacts of herbivore density and promote kelp recovery. To improve outcomes, managers should prioritize the implementation and enforcement of management plans in the TURF to promote herbivore control measures and invest in long‐term monitoring programmes to support adaptive strategies that sustain kelp forest ecosystems and the valuable services they provide to coastal communities.

Conservation of marine biodiversity requires an understanding of the habitats needed to support and replenish species of interest. It also requires knowledge about the abundance and diversity of multispecies assemblages. Variation in the distribution and composition of kelp forests, one of the most productive marine coastal habitats globally, can have major influences on reef fishes—a group of ecologically and socioeconomically important species. In the face of widespread and escalating loss of kelp forests, quantification of these effects is urgently needed to assess and project cascading impacts on biodiversity. Here, we evaluate relationships between kelp forests and associated reef fish populations using a global meta‐analysis of experimental kelp removals and comparative surveys of kelp and adjacent non‐kelp habitats. These analyses show that kelp forests increase the abundance of reef fishes, though the significance of this effect varied depending on the structural complexity of kelp forests. In experimental studies, kelp forests have a significant positive effect on fish species richness, revealing that kelp act as true foundation species by supporting the diversity of associated multispecies assemblages. Importantly, regardless of kelp forest morphology and type of study (observational or experimental studies), kelp forests enhance the recruitment of early life history stages suggesting they are nursery habitats for many reef fish taxa. Lastly, kelp forests differentially affected species with different functional traits; small body size fishes from low trophic levels (e.g., herbivore and detritivores, micropredators, and mesopredators) and large body size fish from higher trophic level (e.g., piscivores, general carnivores) were both facilitated by kelp forests. Taken together, these results indicate that the loss of kelp forest, particularly those with more complex morphology, can reduce total abundance and diversity of fish, with possible cascading consequences for coastal ecosystem function.

Flight initiation distance (FID), the distance at which an organism begins to flee from an approaching threat, is a major component of antipredator escape behavior and a potential indicator of threat perception in fishes. In this study, we analyzed the FID of three important rocky‐reef fish species targeted by spearfishers, which are of commercial and recreational importance. We tested predictions that FID to a diver threat increases with the following factors: (1) fish body size, (2) less restricted access regimes, and (3) increased historical fishing pressure. We studied three size ranges of three rocky‐reef fish species, in three different access regimes (i.e., open access, territorial user rights for fishery areas, no‐take marine protected areas), and in two regions (northern and central region with different levels of fishing pressure depending on the species). We conducted an ANOVA to analyze pairwise interactions. We used the mean square criterion to select the models that best explained the variation of our response variable. Our findings indicate that FID can be distinctly elucidated by factors such as individual size, species, access regimes, and regions. Additionally, our models show that interactions involving regions and either species or size further contribute to explain FID variability. FID was higher in larger fishes and those of higher commercial value, outside marine reserves and in the region with the highest historical fishing pressures (based on landings data). This study supports the predictions that increased FID is associated with the threat posed by spearfishing activities. Furthermore, our findings indicate that spearfishing may already be altering the behavior of rocky‐reef fishes on the north‐central coast of Chile.

Kelp forests support species-rich food webs that predator-prey interactions may sustain. Here, we analyze prey availability and stomach contents of the predatory fish Prolatilus jugularis in an unexplored subtidal kelp forest of Lessonia trabeculata in south-central Chile. In the kelp forest, 42 invertebrate taxa and 1016 individuals were observed. In the diet of P. jugularis, 21 taxa and 130 individuals were identified. Crustacea, particularly amphipods, were the dominant and more frequent taxa in the kelp forest and stomach contents. Annelida and Mollusca were also present in the kelp forest and diets but were less abundant. We did not find a statistically significant correlation between kelp forest and stomach-content prey abundances and frequencies. Also, dominance structure significantly differed between kelps and stomach contents. Our results indicate that P. jugularis could feed in other habitats outside the survey area. Seven predatory fish were sampled in the kelp forest. Pinguipes chilensis was the dominant fish, with 65% of the total fish biomass, followed by P. jugularis with 20%.

Temperate mesophotic reef ecosystems (TMREs) are among the least known marine habitats. Information on their diversity and ecology is geographically and temporally scarce, especially in highly productive large upwelling ecosystems. Lack of information remains an obstacle to understanding the importance of TMREs as habitats, biodiversity reservoirs and their connections with better‐studied shallow reefs. Here, we use environmental DNA (eDNA) from water samples to characterize the community composition of TMREs on the central Chilean coast, generating the first baseline for monitoring the biodiversity of these habitats. We analyzed samples from two depths (30 and 60 m) over four seasons (spring, summer, autumn, and winter) and at two locations approximately 16 km apart. We used a panel of three metabarcodes, two that target all eukaryotes (18S rRNA and mitochondrial COI) and one specifically targeting fishes (16S rRNA). All panels combined encompassed eDNA assigned to 42 phyla, 90 classes, 237 orders, and 402 families. The highest family richness was found for the phyla Arthropoda, Bacillariophyta, and Chordata. Overall, family richness was similar between depths but decreased during summer, a pattern consistent at both locations. Our results indicate that the structure (composition) of the mesophotic communities varied predominantly with seasons. We analyzed further the better‐resolved fish assemblage and compared eDNA with other visual methods at the same locations and depths. We recovered eDNA from 19 genera of fish, six of these have also been observed on towed underwater videos, while 13 were unique to eDNA. We discuss the potential drivers of seasonal differences in community composition and richness. Our results suggest that eDNA can provide valuable insights for monitoring TMRE communities but highlight the necessity of completing reference DNA databases available for this region.

The largely unexplored diversity in temperate mesophotic ecosystems (TME, ~30–150 m depth) has attracted much attention over the past years. However, the number of studies and knowledge of TME diversity and ecology remains limited and geographically restricted. The absence of information on how assemblages vary across environmental gradients and with depth for most regions also limits our capacity to delimit conservation areas and devise management plans effectively. This study focuses on TME from central Chile and describes the depth distribution of reef fishes and benthic invertebrates and algae for the first time. Through the analysis of towed underwater video surveys between 4.7–95.5 m in multiple sites, we show that total reef fish density and richness decrease with depth but increase with local topographic complexity. The depth-related density varies among fish species and trophic groups, and it reverses in the case of Sebastes oculatus, which increases in density with depth. Sponges and gorgonians dominate benthic assemblages below 20 m depth, and brachiopods and anemones increase below 40 and 60 m, respectively. Some of these species form animal forests which, to some extent, replace the shallow-water kelp forests as structural habitat providers. Nevertheless, the reef fish and benthic community do not show a clear structure with depth or across studied sites. We highlight the urgency to intensify and expand the quantitative characterization of these communities, through this and other methodologies, to better define ecological patterns and advance towards conservation plans for TME, including the Souteastern Pacific region.

Marine forests is a term commonly used for coastal marine habitats formed by dense stands of brown macroalgae, typically consisting of kelp and fucoids. These habitats are highly productive, offer habitat to numerous marine organisms, and support a range of invaluable ecosystem services. Despite their importance, marine forests are declining in many regions around the world as a result of interacting global, regional, and local‐scale stressors. Consequently, interest in restoration as a tool to mitigate these declines and reinstate marine forests is growing. Recent reviews have provided insights into marine forest restoration; however, for the most part, a synthesis of restoration success is lacking. A meta‐analysis and quantitative review of published marine forest restoration efforts was conducted to examine: (i) how restoration affects the abundance and morphology of marine forest species; and (ii) trends in marine forest restoration success. The meta‐analysis of 25 studies revealed that restoration positively influences the abundance and morphology of marine forest species. The quantitative review of 63 studies demonstrated that taxa and restoration technique were important factors influencing restoration success, and revealed a bias towards the monitoring and reporting of abundance and morphological response variables. The review also highlighted a lack of monitoring and/or reporting of environmental variables at restoration sites, and limited comparative research across environmental contexts and restored species. It is shown that successful marine forest restoration is possible at experimental scales, but that better monitoring and reporting of restoration efforts, alongside increased project durations, could improve our understanding of restoration success at the ecosystem level. Considerations for future marine forest restoration efforts are also provided. It is hoped that the review will advance marine forest restoration efforts, allowing the preservation of these valuable ecosystems and their associated services.