Dr. Brante-Ramirez, Antonio

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.

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.

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.

Poecilogony is a type of reproduction in which a species produces different types of larvae. Boccardia wellingtonensis, is a poecilogonous polychaete with females producing planktotrophic and adelphophagic larvae, in addition to nurse eggs, in the same capsule that differ in feeding behavior. It is still unclear why planktotrophs do not feed on nurse eggs during the intracapsular development and arrest its growth, while adelphophagic larvae consume nurse eggs and planktotrophic larvae inside the capsule, hatching as advance larvae or as juveniles. Here we characterized the expression of selected miRNAs from these two types of larvae and from adults in order to begin to understand the molecular mechanisms that regulate expression in this type of poecilogony. Results showed that adults and pre-hatching adelphophagic larvae have high levels of expression of miR-125, miR-87a and let-7, while adelphophages at early developmental stage had low levels of expression of miR-87b. Planktotrophic larvae showed low expression level of let-7. This work represents the first step in understanding the role of miRNAs in the development of different larval types in a poecilogonous species. We also propose to B. wellingtonensis as an interesting biological model to study the evolution of larval modes and reproductive strategies of marine invertebrates.

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.

In river ecosystems, spatial complexity as well as anthropogenic factors operating at different temporal and spatial scales are shaping demography, connectivity and population genetic structure of species inhabiting these habitats.Chilina dombeianais a freshwater gastropod with direct development (absence of a free larval phase) that inhabits the Biobio river basin in Chile (36 degrees S). No studies have yet evaluated the spatial patterns of the genetic diversity of this species and the potential factors that influence these patterns. Consequently, in this study, we analyzed the population genetics ofC.dombeianabased on 15 locations along the Biobio river. Eight microsatellite loci were genotyped. Also, at each sampling site, 40 environmental parameters were recorded to characterize them. Results showed thatC.dombeianahas low genetic variability with high population structure. In addition, we detected signs of historical decreases in effective population sizes, unidirectional gene flow (upstream to downstream) and contemporary demographic bottleneck. Spatial subdivisions in populations showed a pattern of isolation by distance. The redundancy analysis and variance partitioning showed that spatial components and dissolved oxygen could explain 28% of the interpopulation genetic variation, while the Random Forest analysis identified significant effects of dissolved oxygen, nitrite and total coliforms on the genetic variability of populations (22%). AlthoughC.dombeianais widely distributed in Chilean rivers, its low dispersal and specific habitat requirements make this species very sensitive to the severe increase in anthropogenic disturbances affecting river ecosystems in recent decades. Long-term monitoring of genetic population conditions and environmental parameters are needed to implement robust management and conservation policies.

The level of parental investment for larval nutrition may determine the life cycle in marine invertebrate species laying egg masses or capsules, where the food available for enclosed individuals would determine time and developmental stage of hatching. Most species show a unique type of larval development. However, few species are poecilogonous and combine more than one development type. Poecilogony, although scarcely studied, allows comparing different patterns of parental reproductive investment, without the phylogenetic effect of the species ancestral modes of development (phylogenetic inertia), to help to understand the factors determining life strategy evolution in marine invertebrates. The poecilogonous polychaete worm Boccardia wellingtonensis encapsulates and incubates its offspring, which then hatches as either planktotrophic larvae or benthic juveniles; while Boccardia chilensis shows a non‐poecilogonous reproductive type, producing only planktotrophic larvae. In this work, we estimated the bioenergetic and biochemical composition of brooding and non‐brooding females of B. wellingtonensis and B. chilensis to compare the costs of reproduction in these two species. Results showed that glucose, protein, lipid, and energy content were significantly higher in non‐brooding than in brooding females of B. wellingtonensis; but also contained significantly more glucose, protein, and lipid than females of B. chilensis (in absolute and relative dry weight values). The poecilogonous species showed higher energy content previous to laying offspring. Our results support the idea that the evolution of a certain reproductive and life history traits in marine invertebrates is related to adaptations in the female's reproductive investment.

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.

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).

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.