Growth ofArgopecten purpuratus(Mollusca: Bivalvia) on a natural bank in Northern Chile: sclerochronological record and environmental controls

Abstract

Daily striae on the shell of the scallop, Argopecten purpuratus, were used to investigate its growth in a protected population within La Rinconada Bay, near Antofagasta (2nd Region, Northern Chile), and to determine how environmental forcings control shell growth. This sclerochronological approach was useful to describe daily shell growth a posteriori. Mean shell growth rates were calculated daily between February and October 1999 from shells of six specimens harvested on 15 October 1999. A multiple regression analysis performed on shell growth and environmental data shows that a temperature increase stimulates shell growth whereas particulate organic carbon concentration might be stressful above 2.5 mg L −1. The lunar cycle might also have an effect on growth, most potent around New Moons, by synchronizing an endogenous oscillator. The age at commercial size (90 mm) was only 10-11 months in La Rinconada Marine Reserve and the von Bertalanffy growth parameters were K = 2.24 y −1 and H ∞ = 117 mm. Differences in shell growth performances between this study and previous ones dealing with A. purpuratus growth may be explained by the different methods used for shell growth modelling, higher growth rate on the seabed compared to suspended cultures, and particular environmental forcings (e.g. El Niño Southern Oscillation-ENSO events). Growth performance seems better during La Niña than during El Niño events, probably because of the large temperature increase (above the highest temperatures recorded in "normal" conditions) and the decline in coastal upwelling (which affects food availability) during El Niño. La Rinconada Marine Reserve appears as a very favourable site for A. purpuratus growth, probably because of the active upwelling zone off Antofagasta. These new insights on A. purpuratus shell growth confirm the importance of La Rinconada Marine Reserve as an area supporting repopulation of endangered wild stocks and scallop aquaculture in Chile.

Simulation model of the scallop (Argopecten purpuratus) farming in northern Chile: some applications in the decision making process

“…To improve performance in the model, it is necessary to have more research related to growth performance of scallop farming in Chile, this matter becomes crucial given that different locations, times, environmental conditions (temperature, oxygen, food availability and ENSO) and farming densities can have significant impacts on scallop growth (Navarro & González, 1998Tarazona et al, 2007). In Chile, there are only a few growth studies conducted (Thébault et al, 2008), and further research should be done under different times of the year and under different environmental conditions (Thébault et al, 2008;Uribe & Blanco, 2001) throughout the farming process (Hawkins et al, 2002). Mortality was also a key factor determining the performance of the model, where variations in the mortality had different effects for both cases (growth conditions).…”

“…This poses a major challenge for research, especially because mortalities will vary between geographical locations and environmental conditions (Navarro & González, 1998;Tarazona et al, 2007). As the information on both growth and mortality is scarce for Chile (Thébault et al, 2008;Uribe & Blanco, 2001), modifications in the model could be done in order to obtain results that can incorporate uncertainty and environmental variability at some extent. A risk analysis of the outcomes from this modification can provide a better insight for the implications of environmental variability in the economic feasibility of scallop farming.…”

Comparacion del crecimiento de Argopecten purpuratus entre cohortes obtenidas de captacion de larvas en ambiente natural y de hatchery

“…La información de edad-longitud fue procesada utilizando la ecuación de crecimiento de von Bertalanffy (Hilborn & Walters, 1991) ECVB, la cual es un buen descriptor del crecimiento en esta especie y ha sido ampliamente utilizada para describir el crecimiento de A. purpuratus (Wolff, 1987;Wolff & Garrido, 1991;Mendo & Jurado, 1993;Thébault et al, 2008). Esta ecuación establece que la longitud a cualquier edad (L t ) depende sólo de la edad (t), de la longitud máxima promedio (L ∞ ), del coeficiente de Brody (K) y de la edad teórica a la cual la longitud fue cero (t 0 ) (…”

Relaciones funcionales entre la temperatura del agua de mar y el coeficiente de Brody en cultivos suspendidos de Argopecten purpuratus

“…Numerosos autores sugieren que en Perú la velocidad de crecimiento es mayor que la reportada para las poblaciones chilenas (Wolff, 1987;Wolff & Garrido, 1991;Avendaño & Cantillánez, 2005;Tarazona et al, 2007;Cisneros et al, 2008;Thébault et al, 2008), debido a las mayores temperaturas observadas en Perú. Recientemente, Pérez et al (2012) mostraron evidencia que no necesariamente una mayor temperatura produce un crecimiento más rápido.…”