Growth and seasonal energetics of the Antarctic bivalve Laternula elliptica from King George Island, Antarctica

Abstract

The Antarctic marine environment is characterized by extreme seasonality in primary production, and herbivores must cope with a prolonged winter period of food shortage. In this study, tissue mass and biochemical composition were determined for various tissues of the bivalve Laternula elliptica (King & Broderip) over a 2 yr period, and its storage and use of energy reserves were investigated with respect to seasonal changes in food level and water temperature. Total ash-free dry mass (AFDM) accumulated rapidly following phytoplankton blooms (with peak values immediately before and after spawning) and was depleted considerably during the spawning and winter periods. Most of the variation was in the muscle, gonads and digestive gland. Spawning peaked in January and February and caused considerable protein and lipid losses in the muscle, gonads and digestive gland. In winter (March to August), the muscle and digestive gland lost considerable mass, while gonad mass increased; this suggests that the muscle tissue and digestive gland serve as major energy depots for both maintenance metabolism and gonad development in winter. There were also marked year-to-year differences in the seasonal patterns of mass variation and reproduction. Overall, the relative and absolute tissue-mass values were positively correlated with chlorophyll concentration, and were not related to water temperature; thus, for the first time, this study clearly shows that food is an important factor governing growth and gonad maturation in this bivalve. It is also noteworthy that protein, constituting ~75% of AFDM, served as the major energy reserve throughout the study, closely following the AFDM variation. In particular, during the winter months, protein comprised >60% of AFDM loss, while lipids and glycogen served as minor (< 20% each) reserves. Protein loss was most substantial in the muscle tissue, which comprised half of the body tissue. Thus, protein use, with muscle tissues as a depot for protein reserves, may be a result of selective pressure on Antarctic marine herbivores undergoing a prolonged period of food shortage in winter.

The reproductive ecology of the Antarctic bivalve Aequiyoldia eightsii (Protobranchia: Sareptidae) follows neither Antarctic nor taxonomic patterns

“…This reproductive trait contrasts with observations of seasonal oogenic development reported in most shallow-water Antarctic marine invertebrates studied to date (e.g. Chiantore et al 2001;Ahn et al 2003;Tyler et al 2003;Grange et al 2004Grange et al , 2007Kang et al 2009;Grange et al 2011;Reed et al 2013a, b), and other closely related protobranch bivalves including the cold water Yoldia hyperborea (Jaramillo and Thompson 2008), where cohorts of oocytes distinguishable in their maturity stage dominate the gonad at different times of year. Continuous oogenesis is observed, however, in some deep-sea protobranch bivalves (Tyler et al 1992;Zardus 2002;Scheltema and Williams 2009;Reed et al 2014).…”

Variación estacional de la composición proximal del mejillón Tagelus peruvianus (Bivalvia: Solecurtidae) del Golfo de Nicoya, Puntarenas, Costa Rica

“…Similares observaciones han sido descritas para otros bivalvos como Ruditapes decussatus y Tapes philippinarum (Beninger & Lucas 1984), Mytella guyanensis (Cruz & Villalobos 1993), Glycymeris glycymeris (Galap et al 1997), Ruditapes philippinarum (Ojea et al 2005), Laternula elliptica (Ahn et al 2003) y Fulvia mutica (Liu et al 2008).…”

The impacts of climate change on Antarctic nearshore mega-epifaunal benthic assemblages in a glacial fjord on King George Island: Responses and implications

“…1.8 • C in February to a minimum of ca. −1.8 • C in August; salinity ranges from 32.6 to 34.3 psu (Ahn et al, 2003;KOPRI, 2012b). Marked summer-time blooms in primary production have been reported, wherein benthic diatoms dominate the water column biomass (Ahn et al, 1997;Kang et al, 2002).…”