Dr. Brante-Ramírez, Antonio

Molluscan veliger larvae and some annelid larvae capture particulate food between a preoral prototrochal band of long cilia that create a current for both swimming and feeding and a postoral metatrochal band of shorter cilia that beat toward the prototroch. Larvae encountering satiating or noxious particles must somehow swim without capturing particles or else reject large numbers of captured particles. Because high rates of particle capture are inferred to depend on the beat of both ciliary bands, arrest of the metatroch could be one way to swim while reducing captures. Larvae in eight families of annelids arrest metatrochal cilia frequently during prototrochal beat, often over a large part of the metatrochal band and with the arrested cilia aligned near the beginning of the effective stroke. In contrast, metatrochs of veligers of gastropods and bivalves rarely arrested while the prototroch beat, and those arrests were more localized and variable in position. This difference in metatrochal arrest was unexpected under hypotheses of either a single origin of this feeding mechanism or multiple origins within each phylum. Although different in metatrochal arrests, larvae of both phyla can separate swimming from feeding while both prototroch and metatroch beat. One hypothesis explaining low rates of capture per encounter, without metatrochal arrest, is a change in adhesion of prototrochal cilia with algae. In a few observations, part of the velar edge was retained within the veliger's shell so that exposed prototrochal cilia contributed to swimming while the adjacent metatroch and food groove were sequestered.

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.

Earthquake/tsunamis can have profound impacts on species and their genetic patterns. It is expected that the magnitude of this impact might depend on the species and the time since the disturbance occurs, nevertheless these assumptions remain mostly unexplored. Here we studied the genetic responses of the crustacean species Emerita analoga, Excirolana hirsuticauda, and Orchestoidea tuberculata to the 27F mega-earthquake/tsunami that occurred in Chile in February 2010. mtDNA sequence analyses revealed a lower haplotype diversity for E. analoga and E. hirsuticauda in impacted areas one month after the 27F, and the opposite for O. tuberculata. Three years after the 27F we observed a recovery in the genetic diversity of E. analoga and E. hirsuticauda and decrease in the genetic diversity in O. tuberculata in 2/3 of sampled areas. Emerita analoga displayed decrease of genetic diferentiation and increase in gene fow explained by long-range population expansion. The other two species revealed slight increase in the number of genetic groups, little change in gene fow and no signal of population expansion associated to adult survival, rapid colonization, and capacity to burrow in the sand. Our results reveal that species response to a same disturbance event could be extremely diverse and depending on life-history traits and the magnitude of the efect.

The geographical expansion of invasive species depends mainly on its dispersal potential, and the abiotic and biotic factors affecting it. Knowing the invasive dynamic of non-native species, as well as its behavior at different natural or anthropogenic scenarios, is fundamental for planning conservation management policies and control plans. The invasive sea anemone Anemonia alicemartinae in habits from the north (18 S) to the south-central (36 S) coast of Chile and its distribution range has expanded by approximately 1,928 km in the last 50 years. Previous works have proposed that human-mediated southward transport associated with regional-scale maritime activities could explain its rapid spread. To evaluate this hypothesis, we used ecological niche models (ENM) to evaluate the potential colonization of the southernmost area of South America. Additionally, we conducted a post hoc analysis to evaluate the relationship between the prediction of the ENM and human activity measured as the number of landings of ships in ports. The models were built based on presence records of A. alicemartinae, and oceanographic variables. Results showed that sea surface salinity and annual sea surface temperature (variance) are the best predictor variables to explain the distribution of A. alicemartinae. There was a positive and significant relationship between the geographical distribution of the sea anemone predicted by the ENM and the number of landings, as a proxy of anthropogenic activity. The most susceptible areas to invasion were those that showed the highest variability in both oceanographic predictors. These areas included the Biobío region, Chiloé´s inland sea, Aysén, and Chacabuco regions, which together comprise two biogeographical provinces. These results sustain the proposed hypothesis and, overall, the results suggest that along with the characteristics of the life history of A. alicemartinae, oceanographic conditions and How to cite this article Pinochet J, Rivera R, Neill PE, Brante A, Hernández CE. 2019. Spread of the non-native anemone Anemonia alicemartinae Häussermann & Försterra, 2001 along the Humboldt-current large marine ecosystem: an ecological niche model approach. maritime transport as vector contribute to the southern range expansion of this invasive cryptogenic species in the Humboldt-current large marine ecosystem.

In marine invertebrates, the modes of development at early stages are related to the type and capacity of larval feeding to achieve growth. Therefore, studying the factors that determine larval feeding strategies can help to understand the diversity of life histories and evolution of marine invertebrates. The polychaete Boccardia wellingtonensis is a poecilogonous species that encapsulates and incubates its offspring. This species produces two types of larvae: (1) larvae that do not feed within the capsule and hatch as planktotrophic larvae (indirect development), and (2) adelphophagic larvae that feed on nurse eggs and other larvae inside the capsule to hatch as advanced larvae or juveniles (direct development). Otherwise, the larval types are indistinguishable at the same stage of development. The non-apparent morphological differences between both types of larvae suggest that other factors are influencing their feeding behavior. This work studied the potential role of the activity of 19 digestive enzymes on the different feeding capacities of planktotrophic and adelphophagic larvae of B. wellingtonensis. Also, differences in larval feeding structures and the larval capacity to feed from intracapsular fluid were evaluated by electron and fluorescence microscopy. Results showed that both types of larvae present similar feeding structures and had the capacity to ingest intracapsular fluid protein. Adelphophagic larvae showed overall the highest activities of digestive enzymes. Significant differences between larval types were observed in nine enzymes related to the use of internal and external nutritional sources. Given that larval feeding is closely related to larval development in species with encapsulation, this work supports that the study of the digestive enzymatic machinery of larvae may contribute to understanding the evolution of developmental modes.

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.

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.

Growing coastal urbanization together with the intensification of maritime traffic are major processes explaining the increasing rate of biological introductions in marine environments. To investigate the link between international maritime traffic and the establishment of non-indigenous species (NIS) in coastal areas, biofouling communities in three international and three nearby local ports along 100 km of coastline in south-central Chile were compared using settlement panels and rapid assessment surveys. A larger number of NIS was observed in international ports, as expected in these ‘invasion hubs’. However, despite a few environmental differences between international and local ports, the two port categories did not display significant differences regarding NIS establishment and contribution to community structure over the studied period (1.5 years). In international ports, the free space could be a limiting factor for NIS establishment. The results also suggest that local ports should be considered in NIS surveillance programs in Chile.

The slipper limpet Crepipatella dilatata, native to Chile and Argentina, was introduced in Spain in 2005. The species was thought to inhabit the region of Rias Bajas, yet recently, putative C. dilatata populations have been documented on the coast of north-central Spain and in the Ebro Delta of the Spanish Mediterranean. Here we undertook a multidisciplinary approach to study the invasion biology of this species. Specifically, two geographically distant populations, one being a successfully established population from O Grove and the other a declining population from Gijon, were studied over the course of four years. Analyses of morphological and developmental traits as well as genetic information confirmed the presence of C. dilatata in these sites. The results revealed polymorphism in anatomical traits and shell shape. Shell shape polymorphism was unevenly distributed among sites and among sexes. Males were monomorphic, while females were polymorphic. Of the female morphotypes encountered, one was absent in the declining population from Gijón. Size at first female maturation and female size were greater in the declining population than in the established population. Reproductive success varied seasonally but not spatially among populations. In the established population, gregariousness was significantly greater; the size when sex changes was found to be plastic and socially controlled. The sex ratio of the declining population was female biased while in the established population the sex ratio changed during the study period from being balanced to being female biased. This change in sex ratio was probably due to higher male mortality. Molecular analyses pointed to the localities of Corral Bay in southern Chile and Puerto Madryn in southern Argentina as potential population sources. The intercontinental import of fresh mussels cultivated in Chilean farms is a likely source of this mussel in Spain. Comparison with available data of native populations of C. dilatata strongly indicate that ecophenotypic plasticity, socially controlled sex change, high gregariousness, increased nurse egg supply to viable larvae during the encapsulated developmental period, later maturation and larger female sizes altogether enhance establishment success of this non-indigenous species. Human-mediated factors like the intraregional mussel trade and transplantation are also likely secondary dispersal mechanisms favouring the spread of this organism.

Studying the mating system of obligate aquatic organisms that inhabit river ecosystems is important for understanding its evolution as well as the role of biological and environmental factors in modulating population dynamics and species distributional patterns. Here, we studied the reproductive strategy of the Chilean endemic freshwater snail, Chilina dombeiana,in the BiobõÂo River, one of the largest rivers in Chile. This species has a low potential for dispersal given the absence of a free-swimming larval stage (benthic larval development)and given that adults have a low capacity for mobility. We hypothesized that: 1. Females would mate with different males (polyandry resulting in intrabrood multiple paternity, 2. Individuals from closer sites would be more related than individuals from distant sites, and 3. Male parental contributions would be unevenly distributed within broods. Individuals from three different sites were sampled along the river: upper, mid, and river mouth. In the laboratory, hatching juveniles from a total of 15 broods were collected for paternity analyses. We used microsatellite markers and the programs GERUD and COLONY to determine whether multiple paternity exists and to estimate the contribution of different males to the brood. We found that multiple paternity was very common at all of the sites analyzed with as many as 8 males fertilizing a single female and a mean of 4.2 fathers per brood estimated by COLONY. Sire contribution was skewed to particular males in several broods. In addition, overall relatedness among broods for the three sites ranged from 0.17 to 0.45 with evidence of many half-siblings. Relatedness differed among the three sites. Particularly in upstream sites or in anthropogenically disturbed populations, the high levels of multiple paternity observed in C. dombeiana may be an efficient strategy to avoid inbreeding and prevent the loss of genetic diversity within populations.