Alvar Carranza

We report live observations of Cirrothauma cf. murrayi, the unique ‘blind cirrate octopus’ at a depth of 3,122 m depth during a SuBastian dive aboard RV ‘Falkor (too)’ in the Economic Exclusive Zone of Uruguay. The observed specimen exhibited an elongated body shape, distinct from a compressed form, with a gelatinous and fragile structure. Notable features include reduced or degenerate eyes, lightly pigmented skin, a deep web with a secondary web, long conspicuous cirri, elongate stalks with minute suckers, and large, wide fins that exceed the width of the head. The oceanographic setting indicates the presence of a mixing layer between the North Atlantic Deep Water (NADW) and the Lower Circumpolar Deep Water (LCDW). This record enhances the limited knowledge of Cirroteuthidae distribution in this region, with previous records restricted to Brazil and the Southern Ocean (South Sandwich Islands), being the first one for the Argentine Basin.

Ecosystems and biodiversity around the globe face multiple threats, including climate change and invasive species. Non-native species are known for their resilience to disturbances and their ability to thrive more successfully than native species in urbanized or otherwise disturbed areas, and some of them can become invasive. It is a complex challenge to detect, manage, and control such species, which require coordinated efforts from society, government, and the academic community. In this study, the eMIAS (South American Invasive Mollusks Specialists) research group (27 experts from seven South American countries) aim to provide foundational knowledge for management of these species. We compiled and synthesized information on the mollusc species that are native to South America and that have been introduced to other regions of the world. A total of 29 species were detected, including 10 marine, 10 freshwater, and 9 terrestrial. For each species, the area of origin, date and place of introduction, and current distribution were determined. We could determine that (1) most of these introductions have occurred in connection with globalization processes, such as an increase in trade. (2) The potential source regions of those 29 species are also areas that received non-native species from elsewhere (e.g., Europe, Asia). (3) Regions where species introductions have taken place are subject to the impacts of climate change and/or urbanization.

Global awareness of introduced species as one of the primary drivers of biodiversity change—causing environmental impacts, and economic and social effects—emphasizes the need to enhance our understanding of these species. Developing a comprehensive database will enable policymakers to identify global bioinvasion patterns and strengthen their capacity to manage them effectively. Aquatic mollusks play a crucial role in the ecosystems they inhabit, influencing food webs and nutrient cycling, and habitat formation and modification. They are also the dominant group in aquaculture, contributing significantly to the economy while also causing economic losses through macrofouling and posing health risks. Despite their importance, information on the introduction, establishment, and dispersal of mollusk species in South America remains scarce and is often confined to the grey literature. With the aim of organizing, increasing, and strengthening the knowledge of non-native and transplanted mollusks in general and aquatic mollusks in particular, 29 specialists in the introduced mollusks of South America, from seven countries, have been working collaboratively since 2016. Each member contributes expertise, data, and bibliographic resources to build the status of the introduced mollusks in South America and provide critical information to prevent future introductions and transplants. In aquatic environments, 41 non-native mollusk species and 18 transplanted species have been identified. Among them, the bivalve Limnoperna fortunei stands out with the greatest economic effect, while the gastropods Lymnaeidae and Thiaridae represent significant health concerns. Although this research represents a major step forward, it also highlights challenges such as the scarcity of taxonomic studies and the limited investigation of vast areas in South America. The information compiled in this review serves as a resource for researchers, policymakers, and the general public when addressing mollusk bioinvasions in South America.

Scientific surveys employing remotely operated vehicles (ROVs) provide valuable imagery for identifying Vulnerable Marine Ecosystems (VMEs). However, there is presently no established framework for distinguishing VMEs from these images. While existing guidelines effectively address certain habitat types, such as scleractinian reefs, dense octocoral gardens, and chemosynthetic ecosystems, achieving consensus becomes more challenging for other habitats. Our investigation centered on two key localized rocky outcrops on the Uruguayan shelf, conducting ROV dives to explore these environments. This study aims to evaluate initial global consensus guidelines for VME identification from imagery and discuss the suitability of these criteria, and report the existence of Hard Bottom Soft Coral Gardens and Sponge associations in the inner Uruguayan shelf. Recognizing these habitats is of utmost importance for the Uruguayan government, which has expressed the intent to safeguard ecologically representative and well-connected systems crucial for marine biodiversity. Las investigaciones científicas que utilizan vehículos operados de forma remota (ROVs) proporcionan imágenes valiosas para identificar Ecosistemas Marinos Vulnerables (EMV). Sin embargo, actualmente no existe un marco establecido para distinguir los EMV a partir de estas imágenes. Si bien las directrices existentes abordan de manera efectiva ciertos tipos de hábitats, como arrecifes escleractinios, densos jardines de octocorales y ecosistemas quimiosintéticos, lograr consenso se vuelve más desafiante para otros hábitats. Nuestra investigación se centró en dos afloramientos rocosos localizados en la plataforma uruguaya, realizando inmersiones con ROV para explorar estos entornos. Este estudio tiene como objetivo evaluar las directrices iniciales de consenso global para la identificación de EMV a partir de imágenes, discutir la idoneidad de estos criterios e informar sobre la existencia de Jardines de Corales Blandos en Fondos Duros y asociaciones de Esponjas en la plataforma interna uruguaya. Reconocer estos hábitats es de suma importancia para el gobierno uruguayo, que ha expresado la intención de proteger sistemas ecológicamente representativos y bien conectados, fundamentales para la biodiversidad marina.

Assessing the extinction risk in marine invertebrates poses serious challenges to conservation biology, due to the magnitude of marine biodiversity, the inaccessibility of most of the marine realm, and the lack of appropriate data on population dynamics and ecology for most species. However, simple life history traits have a huge potential for preliminary screening criteria for assessing large numbers of species whose status is harsh or impossible to evaluate. Body size and trophic position could be strong predictors of extinction risk providing a general framework for the assessment of species vulnerability. We analyzed the Body Size-Trophic Position (BS-TP) relationship along 1,067 genera representing 4,256 nominal species of western Atlantic benthic gastropods. We found that a carnivore diet characterizes 67% of the genera and that, supporting theoretical predictions, the probability of being carnivores as a function of size showed a unimodal trend. For species with adult body sizes larger than 5 cm, a negative association between trophic position and body size was detected. This result points to an energetic restriction for the viability of large species, implying that organisms placed near the BS-TP boundary are extremely vulnerable to environmental changes. With this result, 109 genera from 42 families of carnivore gastropods and 33 genera from 19 families of herbivore gastropods that may be more vulnerable from the analyzed perspective were identified and ranked. Supporting these results, while the most vulnerable genera are not represented in global IUCN assessments, all our ‘top 10’ vulnerable families are being considered in National or Regional Red Lists. Prior to conducting regional or global conservation assessments for invertebrate taxa, screening methods should be strongly considered.

Climate change impacts on fishery resources have been widely reported worldwide. Nevertheless, a knowledge gap remains for the warm-temperate Southwest Atlantic Ocean—a global warming hotspot that sustains important industrial and small-scale fisheries. By combining a trait-based framework and long-term landing records, we assessed species’ sensitivity to climate change and potential changes in the distribution of important fishery resources (n = 28; i.e., bony fishes, chondrichthyans, crustaceans, and mollusks) in Southern Brazil, Uruguay, and the northern shelf of Argentina. Most species showed moderate or high sensitivity, with mollusks (e.g., sedentary bivalves and snails) being the group with the highest sensitivity, followed by chondrichthyans. Bony fishes showed low and moderate sensitivities, while crustacean sensitivities were species-specific. The stock and/or conservation status overall contributed the most to higher sensitivity. Between 1989 and 2019, species with low and moderate sensitivity dominated regional landings, regardless of the jurisdiction analyzed. A considerable fraction of these landings consisted of species scoring high or very high on an indicator for potential to change their current distribution. These results suggest that although the bulk of past landings were from relatively climate-resilient species, future catches and even entire benthic fisheries may be jeopardized because (1) some exploited species showed high or very high sensitivities and (2) the increase in the relative representation of landings in species whose distribution may change. This paper provides novel results and insights relevant for fisheries management from a region where the effects of climate change have been overlooked, and which lacks a coordinated governance system for climate-resilient fisheries.

Introduction: The Uruguayan Exclusive Economic Zone (U-EEZ) is still lacking a technically sound and institutionally agreed system for classifying marine benthic ecosystems. This fact, added to the growing anthropic pressure marine ecosystems face in the U-EEZ, increases the vulnerability of these ecosystems and their associated biodiversity. Despite this, there is valuable and abundant disaggregated environmental and biological information for benthic systems.Methods: In this work, we used ca. 4000 records of all major Phyla of benthic invertebrates to determine discrete benthic regions for the U-EEZ. We looked at the structuring forces of bathymetry, salinity, and water masses. First, we categorized the multivariate structure according to statistical significance to test a priori categories for univariate descriptors. Then, we mapped unique combinations of categories of structuring variables, which largely determine the structure and composition of benthic communities. Operationally, the variables to be analyzed were classified, and subsequently, group (cluster) and SIMPROF analyzes were performed.Results: The results suggest seven bathymetric categories, two of water masses and two of salinity, significantly structuring the benthic communities. The combination of these categories suggests nine discrete benthic marine regions for the U-EEZ, with heterogeneous structural characteristics. Our results provide an initial model of distinct benthic ecological complexes in U-EEZ.Discussion: However, caution should be exerted when using this model during decision-making. For example, implementing use restrictions of benthic areas should rely on further groundtruthing, including direct seafloor observations and collections. The latter is relevant since our system is based on the analysis of accumulated historical data that may or may not represent the current condition of habitats of interest.