Population dynamics of the venerid bivalve Tawera gayi (Hupe, 1854) in the Ushuaia Bay, Beagle Channel

Abstract

SummaryGrowth, productivity and potential for exploitation of the clam Tawera gayi from shallow waters (3-5 m) of Ushuaia Bay, Beagle Channel were investigated. Mean abundance and biomass in the study area were 1091 ± 737 ind. m )2 and 901.83 g SFWM m )2 (shell-free wet mass), respectively. Individual growth was described best by the von Bertalanffy growth model with the parameter values H ¥ ¼ 28.03 mm,Annual production of the population was estimated to be 120.45 g SFWM m )2 year )1, corresponding to a production-to-biomass ratio (P/B) of 0.134 year . The single negative exponential mortality model does not fit the population mortality pattern, but predation by gastropods (Xymenopsis muriciformis, Trophon geversianus, Natica sp.) appears to be the major cause of mortality. These highly mobile predators together with the comparatively slow growth and low turnover of T. gayi in Ushuaia Bay limit its potential for sustainable commercial exploitation.

Differences in shell morphology and internal growth pattern of the Patagonian scallop Zygochlamys patagonica in the four main beds across their SW Atlantic distribution range

“…Shell cuts revealed alternating broad opaque and narrow translucent growth bands (Figs. 2 and 3) such as observed for other bivalve species (Richardson, 2001;Lomovasky et al, 2002Lomovasky et al, , 2005a. In bivalves, the presence of translucent growth bands indicates period of very slow or even halted shell growth (Rhoads and Lutz, 1980;Richardson, 2001), which may be caused by low metabolic rates related to low environmental temperatures (Grizzle and Lutz, 1988;Jones et al, 1990), lack of food (Green, 1973;Beukema and Desprez, 1986;Beukema and Cadée, 1991), and/or by diversion of metabolic products into gamete production (Morton, 1978;Arneri et al, 1998;Lomovasky et al, 2002).…”

Non-linear curve adjustments widen biological interpretation of relative growth analyses of the clam Tivela mactroides (Bivalvia, Veneridae)

“…The power function (allometric equation) was the best model describing five of the eight morphometric relationships analyzed (mainly relationships involving the weight parameters such as shell weight, dry weight and ash-free dry weight). This function is commonly used in morphometric analyses of bivalves (e.g., Clasing et al, 1994 ; Urban & Campos, 1994 ; Gaspar, Santos & Vasconcelos, 2001 ; Lomovasky, Brey & Morriconi, 2005 ), but is normally considered the weakest adjustment for many morphometric relationships in some marine invertebrates ( Katsanevakis, 2007 ; Rabaoui et al, 2007 ; Garraffoni, Yokoyama & Amaral, 2010 ). A main drawback in the use of the power function is that it does not consider breakpoints (i.e., marked changes in the allometric growth) and may hide major indications of morphological variability among individuals of different sizes ( Rabaoui et al, 2007 ).…”

Acondicionamiento de reproductores y caracterización gonadal de Tawera gayi (Hupé, 1854) (Bivalva: Veneridae) bajo condiciones controladas de cultivo.

“…Esta especie habita en zonas frías y se distribuye por el Océano Pacífico, desde Valparaíso hasta el Canal Beagle y por el Océano Atlántico en la desembocadura del Río de la Plata, Argentina y en Nueva Zelanda. (Lomovasky et al 2003). En Chile se encuentra presente en las comunidades de fondos blandos entre los 54 y 27° S ( (Jeréz, 1999;Gordillo, 2006).…”