Dr. Brante-Ramírez, Antonio

Athyonidium chilensis is a sea cucumber species that inhabits both the intertidal and subtidal zones of the southeast coast of the Pacific Ocean. This species is considered a commercially valuable fishery resource in Peru and Chile, which is exported to Asian countries for human consumption as a dried product. Despite its commercial importance, the spatial distribution of the genetic variability in A. chilensis along its geographic range remains unstudied. This information is crucial to define population stocks and to establish science-based management and conservation plans. Hence, our study aimed to assess the genetic structure and diversity of A. chilensis using DNA from adult specimens from six natural banks located between 18 °S and 42 °S. We analyzed 364 sequences from two genes (241 COI sequences and 123 ATPS-b sequences), which not only revealed high genetic diversity among A. chilensis populations from Chile but potentially also the presence of a second, cryptic species. Additionally, significant genetic distances were found among locations, with genetic flow decreasing with increasing spatial distance, suggesting different population stocks along the southeast coast of the Pacific Ocean. We provide crucial, baseline information to move forward with management plans for the preservation of genetic diversity for the species and the fishery to persist.

In coastal Antarctic environments, glacial meltwater changes the nutrients and physicochemical parameters in the water column. Consequently, top-down cascading effects are triggered throughout the food web, which can affect the bioenergetic condition of benthic invertebrates and their coupling processes between energy levels and flows throughout the marine food web. In this study, two benthic polychaetes (Maldane sarsi antarctica and Notomastus latericeus), exposed to the impact of glacial melting over a broad time scale, were used to evaluate the effect of glacial meltwater on their bioenergetic condition through the integrated analysis of: i) their biochemical composition; ii) fatty acid profiles and iii) total energy contents. The findings indicate that glacial meltwater has a direct effect on the bioenergetic condition of polychaetes. In areas where glacial meltwater has a significant impact, N. latericeus showed higher levels of proteins and glucose, but lower levels of lipids. On the other hand, M. sarsi antarctica exhibited decreased protein content with increasing glacial meltwater impact. M. sarsi antarctica presented varying levels of lipids across different sites, with the highest concentrations observed in areas with moderate impact. Both species showed a reduction in fatty acids with increasing glacial meltwater impact. Additionally, M. sarsi antarctica individuals from highly impacted areas had lower energy levels than those from less impacted areas, while N. latericeus had higher energy levels in the most impacted site. This information enables the development of a framework for assessing the impact of climate change using glacial meltwater and the integrated bioenergetics of key benthic polychaeta as a proxy. Therefore, identifying how glacial meltwater affects their bioenergetic condition helps us understand how climate change could affect trophic interactions, structure, and energy flows in the Antarctic marine food web.

In pursuit of a more sustainable construction material with the potential to improve bioreceptivity in marine environments, this study investigates the feasibility of incorporating three industrial residues—steel sludge (“Conox”), mytilid mussel shells, and wheat straw fibers—as partial substitutes for cement and sand. The research focuses on evaluating the physical and mechanical properties of mortar and concrete mixtures containing these residues, both individually and in combination. Additionally, it assesses the metal leaching potential of concrete incorporating Conox sludges into the environment. The results show that mixture containing 10% Conox sludges as a sand substitute exhibit the highest mechanical strength but also increased porosity, water absorption, and chloride ion diffusion. The addition of mussel shells and straw fibers generally reduced mechanical properties and increased porosity in mortars, though a 20% mussel shell substitution maintained mechanical strength and chloride ion diffusion in the concrete. The combination of mussel shells with Conox sludges allowed the concrete to retain its mechanical properties, although it also increased porosity and chloride ion penetration, which may limit its use where impermeability is key. However, this increased porosity could benefit coastal erosion control structures like breakwaters and revetments, and sea walls. Moreover, metal leaching from concrete incorporating Conox sludges remained within established safety limits. Despite these challenges, the materials show promise for non-structural applications or projects where sustainability is prioritized. Our research lays the foundation and opens new possibilities for future investigations that innovate in the combination of industrial wastes, aiming to create more sustainable construction materials with a reduced impact on biodiversity.

Sea cucumbers are important sources of human food and pharmacological compounds. However, few studies have evaluated the potential differences between the sexes or organs in a particular species to explore new commercial opportunities. In this study, the proximate composition and amino acid profile of the body wall, the saponin content in the organs of Athyonidium chilensis males and females, and their cytotoxicity against colon cancer cells were evaluated. There were no significant differences in the proximate composition and amino acid profile of the body wall between the sexes. Protein content differed significantly between organs and sexes, fluctuating between 36.29 % and 72.98 % (dry weight). Saponin content was significantly higher in the gonads and lower in the longitudinal musculature. Cell viability was significantly lower (9.50 ± 2.23 %) with the digestive system saponin extract than with 40 % (94.75 ± 2.65 %). This work demonstrates the great potential of A. chilensis as a food and source of saponins with pharmacological importance.

The estuarine crab Hemigrapsus crenulatus has a wide distribution range along the coast of the South Pacific Ocean (from 20 °S to 53 S°). This decapod is abundant in these coastal and estuarine habitats and plays a key ecological role as prey of the snook fish (Eleginops maclovinus) and kelp gull (Larus dominicanus). Its diet consists of detritus, dead fish, and crustaceans, and the macroalgae Ulva sp. In response to contrasting environmental conditions and anthropogenic impacts along the Chilean coast, H. crenulatus may present intraspecific variations in its reproductive traits and changes in the elemental composition of its embryos, directly affecting its biological fitness. Along the Chilean coast, female individuals were collected during late spring 2019 and early summer 2020 (from November 2019 to February 2020) in six areas of Chile (north: Tongoy (30°S); south-central: Lenga (36°S), Tubul (37°S); south austral: Calbuco (41°S), Castro (42°S), Quellón (43°S). The environmental conditions (i.e. sea surface temperature, precipitation and chlorophyll α) present during each sampling event were also recorded. We evaluated the reproductive parameters of females (fecundity, reproductive output (RO)) as well as their body size (carapace width and dry weight), volume, water content, dry weight, elemental composition (carbon, hydrogen, nitrogen: CHN), and finally the energy content of their embryos. Our results indicated that the environmental conditions of the sea water temperature, precipitation (proxy of water salinity) and chlorophyll α (proxy of food availability) have direct effects on the reproductive parameters of females and the characteristics of their embryos. We observed a low fecundity and high RO in Calbuco and Quellón, where precipitation was high (i.e. diluted salinity) and temperatures and productivity was low. For embryo traits, the highest values of volume and water content were observed in female crabs from the estuarine areas (i.e. Tongoy, Lenga, Tubul), values much higher than those found in the internal sea of Chile (i.e. Calbuco, Castro, Quellón). For the elemental composition, we observed high nitrogen levels and a low C:N proportion in embryos from female crabs from Lenga (a nitrogen enriched area). Fluctuating environmental variables among localities proved to modulate intraspecific variations in females and embryos of H. crenulatus, revealing different reproductive strategies, particularly in the quality and energy investment per embryo, which subsequently influenced successful embryogenesis and larval survival.

Established non-native sea anemone populations can affect the native community through multiple mechanisms, including predation and competition. The conservation of invaded communities is therefore of great concern, and spatially explicit information is essential for the prevention or early detection of introductions. Here, we used ecological niche modeling to (1) predict areas with invasion risk of 3 successful widespread invasive sea anemone species (Diadumene lineata, Exaiptasia diaphana, and Nematostella vectensis); (2) determine the invasion stage of current non-native occurrences; and (3) test the climatic match hypothesis of invasion success by assessing their environmental niche dynamics. Our results bring new insights to the invasion process of sea anemones, which is relevant considering the scarcity of monitoring efforts, the issues associated with their detection, and the potential ecological effects they generate on invaded communities. First, we provide potential distributions that could help to detect non-native populations early on. Second, we confirm a strong pattern of successful establishment. Finally, we demonstrate that the invasion success of these species has mainly occurred in areas with environmental conditions similar to those from their respective native ranges (i.e. climatic match, niche conservatism).

Among anthropogenic habitats built in the marine environment, floating and non-floating structures can be colonized by distinct assemblages. However, there is little knowledge whether these differences are also reflected in the functional structure. This study compared the functional diversity of sessile and mobile invertebrate assemblages that settle over three months on floating vs. non-floating artificial habitats, in two Chilean ports. Using morphological, trophic, behavioral, and life history traits, we found differences between mobile and sessile as-semblages regarding the effect of the type of habitat on the functional diversity. Compared to sessile assemblages, a greater functional similarity was observed for mobile assemblages, which suggests that their dispersal capacity enables them to balance the reduced connectivity between settlement structures. No traits, prevailing or selected in one or the other habitat type, was however clearly identified; a result warranting for further studies focusing on more advanced stages of community development.

Inbreeding depression strongly affects the biological fitness of organisms throughout their life cycle. These negative effects are more pronounced in species with low dispersal potentials, where mating among relatives is more likely. However, in some species, an outbreeding depression could be expressed when local adaptive and genetic beneficial interactions are disrupted when mating occurs between individuals from different localities. The amphipod Orchestoidea tuberculata inhabits the upper level of sandy beaches. This species has direct development and adults are poor swimmers, resulting in low dispersal potential. We herein evaluated potential inbreeding and outbreeding depression responses in O. tuberculata estimated in fecundity, egg size, and mate choice. Artificial families were used with individuals from different sites within a single beach and from distinct beaches. Results showed that the highest fecundity (66.7%) and the largest egg size (50.1 mm3) were recorded in females that mated with males from the same site, rather than males from other sites and beaches. We also observed potential recognition mechanisms that clearly favored inbreeding (81.8% of males chose females from the same site). These results suggest a potential outbreeding depression in O. tuberculata. Additional studies are needed to elucidate underlying adaptive mechanisms favoring inbreeding in this species.

Many Caribbean nations lack information on the ecology and biology of marine species, which are essential for food security and livelihoods in the region. This study aimed to advance the knowledge of two commercially important fish species, lane snapper (Lutjanus synagris) and white grunt (Haemulon plumierii), using cost-efficient techniques. Specifically, geometric morphometrics was used to assess the presence of ecomorphological groups (characterized by body shape variation associated with local environmental variables) in the Honduran Caribbean continental platform. Photographs of 104 lane snapper and 99 white grunt adult individuals were taken and digitalized with 12 landmarks. Subsequently body shape patterns were related to environmental variables using Distance-based linear models and Partial Least Squares. Results enabled the identification of ecomorphological groups or fish stocks in the study region associated with the environmental conditions of each site. Distance to river mouth and Chlorophyll a, both indicators of land-based stressors, appeared as the primary driving force of body shape differentiation in the species. These results are key for the development of informed reef fisheries management policies in the Caribbean region.

Of the suite of species interactions involved in biotic resistance to species invasions, predation can have complex outcomes according to the theoretical and empirical framework of community ecology. In this study, we aimed to determine the likelihood of consumptive biotic resistance within fouling communities in four ports of central Chile. Notably, we examined the influence of micro- (> 1–2 mm, < 1–2 cm) and macro- (> 1–2 cm) predators, with a particular focus on their effects on non-indigenous species (NIS). Experimental and observational approaches were combined. An exclusion experiment was carried out over 4 months to examine predator effect on the early establishment of new assemblages on settlement panels. Later successional stages upon panels were examined over a total of 26 months and supported by rapid assessment surveys in the surrounding habitats. Community structure was significantly influenced by the exclusion treatments. Macropredators reduced the fouling biomass and abundance, although conflicting patterns emerged from the exclusion of both categories of predators. Altogether, predators reduced the abundance of most NIS and cryptogenic species, some of them being only observed when the two categories of predators were excluded—a pattern generally sustained over the long-term dynamics in community development. Our results show an effective consumptive biotic resistance, furthermore possibly dependent on predator size. Further work is however needed to determine the influence of the functional diversity of natural enemies on the efficiency of biotic resistance and its interplay with other biotic interactions (competition or mutualism). A comprehensive understanding of these processes should in turn help defining management strategies in a context of habitat modification and species loss.