Research Outputs
Habitat type drives the distribution of non-indigenous species in fouling communities regardless of associated maritime traffic
Biological invasions and changes in land and sea use are among the five major causes of global biodiversity decline. Shipping and ocean sprawl (multiplication of artificial structures at the expense of natural habitats) are considered as the major forces responsible for marine invasions and biotic homogenization. And yet, there is little evidence of their interplay at multiple spatial scales. Here, we aimed to examine this interaction and the extent to which the type of artificial habitat alters the distribution of native and non‐indigenous biodiversity. Location: Southeast Pacific—Central Chilean coastline.
Presence of the tunicate Asterocarpa humilis on ship hulls and aquaculture facilities in the coast of the Biobio Region, south central Chile
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.
Critical swimming speed at different temperatures for small-bodied freshwater native riverine fish species
This study evaluated the efect of fsh total length (LT) and three water temperatures (10, 15 and 20 °C) on the critical swimming speed (Ucrit) of the species Percilia irwini (2.9–6.3 cm LT), Cheirodon galusdae (3.4–5.5 cm LT), and Trichomycterus areolatus (4.0–6.3 cm LT). An Ucrit estimation model was constructed for each species as a function of temperature and size. The results showed mean Ucrit for P. irwini of 44.56, 53.83 and 63.2 cm s−1 at 10, 15 and 20 °C, respectively: 55.34, 61.74 and 70.05 cm s−1 for C. galusdae and 56.18, 63.01 and 71.09 cm s−1 for T. areolatus. Critical velocity depended on the interaction between species, body length and water. The swimming performance increased signifcantly with rising temperature in all three species. The velocity also increased with greater fsh total length. After controlling for fsh total length, velocity also increased with higher temperature in the three species. This research is relevant to small fsh species that require conservation measures.
Settlement experiment of spat using three different collectors in two contrasting coastal sites from Chile (SE Pacific Ocean)
Most of the marine bivalve production comes from aquaculture and only 11% comes from the wild fishery. For example, mussel aquaculture still strongly relies on spat - the recently settled juveniles. Gaps of information on the recruitment and settlement of spat are important drawbacks for the development of mussel aquaculture in several geographic regions. We here study these processes using three collectors (Anchovy mesh, Rope and Raschel mesh) throughout one year in two coastal sites of Central Chile (Coliumo and Punta Lobería) at three depths (2, 4 and 6 m). Five spat species were settled in the collectors, i.e. Aulacomya atra, Choromytilus chorus, Mytilus chilensis, Mytilus galloprovincialis and Semimytilus algosus. Recruitment was consistently higher during summer and autumn at both sites. Different seasonal recruitment patterns were observed regarding the spat species. Spat collection of the former mytilid species occurs from spring to autumn with the exception of M. galloprovincialis in Coliumo and M. chilensis in Punta Lobería. M. galloprovincialis is settled mostly in autumn and summer, and M. chilensis during winter. There were also differences when considering the collector type, mostly due to A. atra and S. algosus which peaked in nylon rope. Spat collection of the commercial species M. chilensis should be preferentially carried out in nylon rope during autumn in Coliumo and summer and autumn in Punta Lobería. During summer and autumn, also S. algosus will be settled. These results will enable the implementation of management measures to promote mytilid culture on the coastal zone of the Biobío region.
Cultivo en suspensión de Mytella guyanensis (Bivalvia:Mytilidae) en Isla Chira, Costa Rica: implicaciones ambientales y biológicas
La maricultura artesanal surge en las últimas décadas como una actividad productiva para el desarrollo socioeconómico de las islas del Golfo de Nicoya en Costa Rica. Determinar las condiciones ambientales y biológicas para impulsar el cultivo de Mytella guyanensis representa un gran insumo para el manejo y la comercialización de estos bivalvos de forma sostenible. Se evaluó el crecimiento, la mortalidad y su relación con los parámetros ambientales en un medio de cultivo en suspensión en Isla Chira. Durante 6 meses (octubre 2018-marzo 2019), se registraron los principales parámetros ambientales del medio de cultivo, se realizaron biometrías a 300 individuos de la población cultivada y, además, se estimó la tasa de mortalidad mediante el procesamiento de 60 canastas de mejillón. En términos generales, a) los parámetros físico-químicos monitoreados presentaron condiciones aptas para el cultivo de estos organismos, b) se registró una tasa de mortalidad del mejillón mensual promedio de 13 %±4,5; y c) M. guyanensis alcanzó un tamaño apto para su comercialización y consumo (≥40 mm de longitud) a partir del cuarto mes de cultivo. El crecimiento de M. guyanensis mediante el sistema de producción en canastas suspendidas, tiende a suceder con mayor rapidez con respecto a su crecimiento en bancos naturales. El futuro de la Maricultura, dependerá en gran medida del seguimiento de los parámetros físico-químicos, de la caracterización de rangos óptimos para las especies cultivadas, como también, de la identificación de nuevos sitios aptos para cultivar.