Dr. Brante-Ramírez, Antonio

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.

The intertidal mussel Perumytilus purpuratus exhibits phenotypic plasticity in response to predation threats, with these responses influenced by the mussels' perception of predation risk. These adaptations, however, are constrained by energy costs and interactions with environmental factors that may trigger synergistic effects or trade-offs among different fitness traits. In particular, this study focuses on the anti-predatory responses of P. purpuratus against the sea star Meyenaster gelatinosus, examining how the presence of the predator and water flow strength influence these responses. The research was conducted through laboratory experiments, comparing mussels from two distinct localities with varying predation risks posed by M. gelatinosus: Punta Hualpén, where the predator is naturally present, and Coliumo, where it is absent. The anti-predatory responses were assessed by measuring attachment strength, byssus production, and adductor muscle mass in the presence of predator cues. Additionally, potential costs associated with these responses were estimated using the gonadosomatic index as a measure of reproductive investment. The findings indicate that the anti-predatory responses of P. purpuratus are contingent on the mussel's origin, with adhesion strength and byssus production negatively impacting reproductive investment. Moreover, the study highlights the intricate interplay of multiple factors, as evidenced by the complex adaptive mechanisms observed in P. purpuratus. The interaction between predator presence and water flow strength and their combined effects on various traits underscores the need for comprehensive multifactorial experiments to understand these adaptive processes. In conclusion, this study provided valuable insights into the nuanced and site-specific nature of anti-predatory responses in P. purpuratus. The research emphasizes the importance of considering multiple factors and conducting comprehensive experiments to unravel the intricacies of adaptive mechanisms in prey species.

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 mussels Perumytilus purpuratus and Semimytilus algosus are two dominant species of intertidal rocky shores of central Chile. These species have marked differences in their distribution patterns with P. purpuratus dominating the mid-intertidal zone and S. algosus dominating the lower intertidal zone usually in habitats influenced by sand. Although it has been suggested that differences in tolerance to environmental conditions, such as air exposure and presence of sand, can explain the distribution of these species, there are currently no experimental studies to support such hypotheses. Here, we evaluated the growth and survival rate in the field of both mussel species at four different tidal heights: 25, 75, 135, and 175 cm above the zero tide. In addition, filtration rates were estimated for both species in the presence and absence of sand in laboratory conditions. The results showed that shell and wet weight growth rates of P. purpuratus were highest in mid- and medium-high tidal heights, whereas the growth rate of S. algosus was highest in the medium-low level. Similar pattern was observed for survival percentage. Furthermore, small S. algosus individuals cultivated with sand in suspension had significantly higher filtration rates than P. purpuratus. In large individuals, no differences were observed between the two species nor between treatments (presence and absence of sand). These results indicate that the differences in the distribution patterns of P. purpuratus and S. algosus in the intertidal can be explained by differences in physiological tolerances to both air exposure and to the presence of sand.

Non-native ascidians are important members of the fouling community associated with artificial substrata and man-made structures. Being efficient fouling species, they are easily spread by human-mediated transports (e.g., with aquaculture trade and maritime transports). This is exemplified by the ascidian Asterocarpa humilis which displays a wide distribution in the Southern Hemisphere and has been recently reported in the Northern Hemisphere (NW Europe). In continental Chile, its first report dates back from 2000 for the locality of Antofagasta (23_x000E_S). Although there was no evidence about the vectors of introduction and spread, nor the source, some authors suggested maritime transport by ship hulls and aquaculture devices as putative introduction pathways and vectors. In the present study, we report for the first time the presence of A. humilis on the hull of an international ship in a commercial port in Concepción bay (36_x000E_S), south central Chile. We also found one individual associated to a seashell farm, 70 km far from Concepción bay. Further individuals were subsequently identified within Concepción bay: one juvenile settled upon international harbor pilings and a dozen individuals along aquaculture seashell longlines. For the first specimens sampled, species identification was ascertained using both morphological criteria and molecular barcoding, using the mitochondrial gene cytochrome c oxidase subunit I (COI) and a nuclear gene (ribosomal RNA 18S). The nuclear 18S gene and the mitochondrial gene COI clearly assigned the specimens to A. humilis, confirming our morphological identification. Two haplotypes were obtained with COI corresponding to haplotypes previously obtained with European and Northern Chilean specimens. The present study thus reports for the first time the presence of A. humilis in the Araucanian ecoregion, documenting the apparent expansion of this non-native tunicate in Chile over 2,000 km, spanning over three ecoregions. In addition we reveal the potential implication of the international maritime transport as a vector of spread of this species along the Eastern Pacific coast, and the putative role of aquaculture facilities in promoting local establishments of non-native tunicates.