Standardized methods for effectively and rapidly monitoring changes in the biodiversity of marine ecosystems are critical to assess status and trends in ways that are comparable between locations and over time. In intertidal and subtidal habitats, estimates of fractional cover and abundance of organisms are typically obtained with traditional quadrat-based methods, and collection of photoquadrat imagery is a standard practice. However, visual analysis of quadrats, either in the field or from photographs, can be very time-consuming. Cutting-edge machine learning tools are now being used to annotate species records from photoquadrat imagery automatically, significantly reducing processing time of image collections. However, it is not always clear whether information is lost, and if so to what degree, using automated approaches. In this study, we compared results from visual quadrats versus automated photoquadrat assessments of macroalgae and sessile organisms on rocky shores across the American continent, from Patagonia (Argentina), Galapagos Islands (Ecuador), Gorgona Island (Colombian Pacific), and the northeast coast of the United States (Gulf of Maine) using the automated software CoralNet. Photoquadrat imagery was collected at the same time as visual surveys following a protocol implemented across the Americas by the Marine Biodiversity Observation Network (MBON) Pole to Pole of the Americas program. Our results show that photoquadrat machine learning annotations can estimate percent cover levels of intertidal benthic cover categories and functional groups (algae, bare substrate, and invertebrate cover) nearly identical to those from visual quadrat analysis. We found no statistical differences of cover estimations of dominant groups in photoquadrat images annotated by humans and those processed in CoralNet (binomial generalized linear mixed model or GLMM). Differences between these analyses were not significant, resulting in a Bray-Curtis average distance of 0.13 (sd 0.11) for the full label set, and 0.12 (sd 0.14) for functional groups. This is the first time that CoralNet automated annotation software has been used to monitor “Invertebrate Abundance and Distribution” and “Macroalgal Canopy Cover and Composition” Essential Ocean Variables (EOVs) in intertidal habitats. We recommend its use for rapid, continuous surveys over expanded geographical scales and monitoring of intertidal areas globally.

Underwater sampling needs to strike a balance between time-efficient and standardized data that allow comparison with different areas and times. The roving diver survey involves divers meandering and actively searching for species and has been useful for producing fish species lists but has seldom been implemented for benthic taxa. In this study, we used this non-destructive technique to register species associated with kelp forests at the sub-Antarctic Bécasses Island (Beagle Channel, Argentina), detecting numerous species while providing the first multi-taxa inventory for the area, including macroalgae, invertebrates, and fish, with supporting photographs of each observation hosted on the citizen science platform iNaturalist. This research established a timely and cost-effective methodology for surveys with scuba diving in cold waters, promoting the obtention of new records, data sharing, and transparency of the taxonomic curation. Overall, 160 taxa were found, including 41 not reported previously for this area and three records of southernmost distribution. Other studies in nearby areas with extensive sampling efforts arrived at similar richness estimations. Our findings reveal that the roving diver survey using photographs is a good approach for creating inventories of marine species, which will serve for a better understanding of underwater biodiversity and future long-term monitoring to assess the health of kelp environments.

The Marine Biodiversity Observation Network Pole to Pole of the Americas (MBON Pole to Pole) conducted two workshops on 27-31 March 2023 and 22-26 January 2024 in the Argentinian Patagonia aiming to enhance capacity for long-term monitoring of rocky intertidal communities in Argentina and Chile by applying novel and easy-to-use methods for biodiversity observing. In these workshops, participants received training on the collection and processing of benthic photo-quadrat imagery and their analysis using open-source artificial intelligence applications. Workshop participants included park rangers, undergraduate and graduate students and scientists. These training activities covered theoretical concepts of rocky shore ecology and field exercises. The workshops promoted collaboration and knowledge exchange between users of biodiversity data and ecologists resulting in the development of a standardised biodiversity monitoring protocol for rocky intertidal communities available in the Ocean Best Practices System of the Intergovernmental Oceanographic Commission of UNESCO. Participants learned to identify dominant species and functional groups (e.g. macro-algal taxa, molluscs, barnacles) commonly present in these habitats and their zonation patterns along elevation gradients, capture high-quality benthic photographs using quadrat frames and cameras provided by the MBON Pole to Pole and compute percentage cover estimates of observed taxonomic groups using open-source automated classifiers. Emerging recommendations underscored the importance of actively involving park rangers in survey efforts and facilitating communication with decision-makers managing Marine Protected Areas. These activities were endorsed by the UN Decade as contributions to the Marine Life 2030 programme towards increasing capacity in the implementation of coordinated, standardised and sustained biodiversity observing efforts in the Americas.

Temperate rocky reefs in Atlantic Patagonia are productive areas that support a high diversity of invertebrates, algae, and fishes. Complex surface structures on rocky reefs offer a range of microhabitats, which in turn, lead to a broad variety of co-existing species. Despite their ecological importance and the ecosystem services they provide, Patagonian rocky reef habitats have received limited attention. Until now studies have not discerned nor consequently described the assemblages found on each of the different surface orientations, namely horizontal, vertical, overhang and cavefloor. During this study we developed a protocol for sampling different surface orientations on subtidal rocky reefs using georeferenced high-resolution photoquadrats. We described and compared the epibenthic assemblage of surface orientations on 7 rocky reefs within 1–25 m depth in a northern Patagonia gulf. A total of 70 taxa were identified (12 macroalgae, 44 invertebrates, 10 tunicates, and 4 fishes), which doubles the number of species previously reported for the area. Each surface orientation presented a different assemblage structure while species richness was higher on vertical surfaces. The overhang surfaces had the most distinct assemblage conformed by cnidarians, tunicates, sponges and the absence of algae. The average overall species richness increased with depth due to the increase of sponge and tunicate species. Our results highlight the need of including several surface orientations in rocky reef biodiversity monitoring. This study offers a protocol for large-scale programs aimed at monitoring changes in biodiversity, which is broadly accessible and will provide accurate information. With robust yet simple, non-destructive and relatively low-cost practices this protocol can adequately assess changes in marine habitats, which provide important ecosystem services.

An unexpected predator‐prey interaction is reported between two successful invasive species in Patagonia, the European green crab Carcinus maenas (Linnaeus, 1758) and the potentially neurotoxic grey side‐gilled sea slug Pleurobranchaea maculata (Quoy & Gaimard, 1832). On two different occasions, a total of four crabs were observed preying upon the sea slugs in the field. The establishment of a novel predator‐prey interaction between these species can imply significant effects on their potential spread and invasive success along the South Western Atlantic, as well as it provides a noteworthy contribution towards the knowledge of the currently underexplored question related to what eats the sea slugs.