Get access

Population structure, growth and production of a recent brachiopod from the Chilean fjord region

Authors

  • Sebastian Baumgarten,

    1. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
    2. Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
    Search for more papers by this author
  • Jürgen Laudien,

    Corresponding author
    1. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
    • Correspondence

      Jürgen Laudien, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.

      E-mail: juergen.laudien@awi.de

    Search for more papers by this author
  • Carin Jantzen,

    1. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
    Search for more papers by this author
  • Verena Häussermann,

    1. Pontificia Universidad Católica de Valparaíso, Facultad de Recursos Naturales, Escuela de Ciencias del Mar, Valparaíso, Chile
    2. Huinay Scientific Field Station, Huinay, Chile
    Search for more papers by this author
  • Günter Försterra

    1. Pontificia Universidad Católica de Valparaíso, Facultad de Recursos Naturales, Escuela de Ciencias del Mar, Valparaíso, Chile
    2. Huinay Scientific Field Station, Huinay, Chile
    Search for more papers by this author

Abstract

Magellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind m−2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co-occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (L) of 71.53 mm and a Brody growth constant (K) of 0.336 year−1. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8–5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM ind−1 year−1 at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM year−1 m−2 (1–57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (inline image-ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).

Get access to the full text of this article

Ancillary