Research Outputs
Responses of the mussel Perumytilus purpuratus (Bivalvia, Mytilidae) to hydrodynamic conditions and the presence of predators
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.
Aggressive interactions between the invasive anemone Anemonia alicemartinae and the native anemone Phymactis papillosa
The distribution range expansion of species mediated by natural or anthropic mechanisms is one of the main causes of changes in biodiversity patterns. Anemonia alicemartinae is a cryptogenic species found along the coasts of the Southeast Pacific Ocean. This species has expanded its range by >1900 km along the Chilean coast throughout the last 50 yr. A. alicemartinae cohabits with the native anemone Phymactis papillosa in the low intertidal zone, and given the limited mobility of both species, limited space could encourage aggressive behavior between them. P. papillosa shows different color phenotypes, and, as in other anemone species, color is associated with its level of aggressiveness. Here, we evaluated the aggressive behavior of A. alicemartinae on 2 color morphotypes of P. papillosa. Also, intraspecific agonistic interactions were considered in individuals of A. alicemartinae from 2 localities. Four experiments were conducted: (1) individual vs. individual, (2) individual vs. group forming a frontal line, (3) individual vs. group surrounding the individual and (4) group vs. group. Results showed A. alicemartinae to be a weak competitor against P. papillosa. The cryptogenic species lost more contests with green P. papillosa than with the red phenotype. Few aggressive interactions between conspecifics of A. alicemartinae were found. Results suggest that the expansion success of A. alicemartinae could be explained by alternative strategies, such as escape behavior, asexual reproduction and high dispersal potential.
Post-settlement movement as response to interspecific competition between the bioengineer mussels Semimytilus algosus and Perumytilus purpuratus
Post-settlement movement has been reported mainly in marine species with low or reduced adult mobility, where distribution varies in accordance with ontogeny, thus avoiding or reducing environmental stress or biological interactions. Mussels show high dispersal at the larval stage, and settlement is a highly complex process in which larvae must choose an appropriate site to attach. Although adults are mainly sedentary, it has been shown that they move on a local scale during the benthic phase in response to physical and biological factors. Semimytilus algosus and Perumytilus purpuratus are two bioengineer mussel species cohabiting most of the Chilean rocky shores. While S. algosus occurs in the low intertidal zone, P. purpuratus dominates the mid and mid-high zones. Field and laboratory experiments have shown that S. algosus is a weak competitor with respect to P. purpuratus, and post-settlers present high mobility to relocate in the intertidal. Under this scenario, we evaluated the dispersal behavior of juveniles and adults of S. algosus as a potential response to competition with P. purpuratus. We also measured the attachment strength of S. algosus in the presence of its competitor, as a measure of its escape response ability. Our results showed that the presence of P. purpuratus increased the movement activity of juveniles and adults of S. algosus and decreased their attachment strength. Field experiments carried out with marked individuals in a Chilean rocky shore, showed that S. algosus exhibits higher local dispersion in the zone where P. purpuratus is present. Mussels' high dispersal ability throughout the whole benthic phase may not only serve to reach the optimal physiological position in the intertidal, but also to reduce competition interaction.