Microphytobenthos seasonality determines growth and reproduction in intertidal bivalves

Abstract

The annual cycles of phytoplanktonic and microphytobenthic biomasses as food sources for intertidal bivalves were investigated in a temperate estuarine muddy sandflat of Kwangyang Bay (Korea) from January to December 2002. Seasonal patterns in growth and reproductive activity of a suspension-feeder Laternula marilina and a deposit-feeder Moerella rutila were examined in order to assess their relationship with the annual cycles of pelagic and benthic microalgae, and were combined with analyses of δ 13 C and δ 15 N of bivalve tissues and their potential food resources. Biomasses of phytoplankton and microphytobenthos peaked in late spring-summer, and demonstrated a unimodal pattern of seasonal variation. Photosynthetic pigment composition showed a predominance of diatom marker pigment, fucoxanthin, in the water and the sediments throughout the year. Similar patterns of annual cycles in pelagic and benthic microalgal biomasses and similarities in taxonomic composition indicated that resuspended microphytobenthos is an important contributor to the bay's phytoplankton component. This was supported by the δ 13 C values of suspended particulate organic matter (POM) and physical characteristics of the bay. Synchrony in growth and reproductive activity was observed for both bivalves: their shell and tissue growth and gonadal development were achieved together during late spring and summer when chlorophyll a (chl a) concentrations were highest. This temporal coupling of macrofaunal and microalgal processes indicated that the activities of intertidal bivalves might depend largely on microphytobenthos seasonality. The isotopic signatures of the bivalve tissues demonstrated their dependence on organic matter of microphytobenthic source irrespective of season, despite a comparable contribution of phytoplankton to the diet of the suspension-feeding bivalve. These results highlight the importance of seasonal development of microphytobenthos as an available food source during the critical period of gamete production and growth for both suspension-and deposit-feeding bivalves.

Dissolved inorganic nitrogen uptake by intertidal microphytobenthos: nutrient concentrations, light availability and migration

“…The pigments were extracted with 5 ml of acetone (90%) for 24 h at -20°C. The subsequent HPLC analysis method is described in Kang et al (2006). MPB cell counts were carried out using an inverted micrcoscope (LEICA); total cell numbers were counted on 150 grids on a grid counting chamber (5250 grids, 500 μl sample).…”

Spatial dietary variations in Laternula marilina (Bivalva) and Hediste spp. (Polychaeta) along environmental gradients in two brackish lagoons

“…Tsuchiya & Kurihara 1979, Tenore 1983, see review Lopez & Levinton 1987). However, recent stable isotopic studies have emphasized the trophic importance of locally produced microalgae for benthic detritivores in estuarine and coastal habitats (Sullivan & Moncreiff 1990, Page & Lastra 2003, Yokoyama et al 2005, Kang et al 2006. Only a few studies have shown a significant dietary contribution from terrestrial plant detritus (e.g.…”

“…complex (H. atoka, H. diadroma, and H. japonica) and the bivalve Laternula marilina are commonly found in Asian brackish waters , Sato & Nakashima 2003, Kanaya 2005, Kang et al 2006. Hediste spp.…”

“…are surface-deposit feeders that ingest sediment organic matter (SOM) at the sediment surface, with little selectivity (Tsuchiya & Kurihara 1980, Kikuchi & Wada 1996. L. marilina is an infaunal suspension feeder that ingests particulate organic matter (POM) in the water column using a siphon (Tsuchiya & Kurihara 1980, Kang et al 2006. These species often dominate the estuarine macrozoobenthic community (Kurihara et al 2000, Kanaya 2005, Kang et al 2007) and thus may play significant roles in the local food webs.…”

Shellfish Aquaculture from Space: Potential of Sentinel2 to Monitor Tide-Driven Changes in Turbidity, Chlorophyll Concentration and Oyster Physiological Response at the Scale of an Oyster Farm

“…Although MPB main ecological functions are carried out when it is organized in the form of biofilms, benthic microalgae can also be resuspended into the water column together with other sedimentary particles throughout the tidal cycle (Koh et al, 2006;Ubertini et al, 2012). This can result in significant enrichment of nearshore waters with a high concentration of chlorophyll a (chl a) that becomes available food for suspension feeders such as the Pacific oyster Crassostrea gigas and other commercially and ecologically important bivalves (Kang et al, 2006;Choy et al, 2009). In coastal zones, despite the high contribution of tidal flats to primary production (Underwood and Kromkamp, 1999), the spatial distribution and temporal dynamic of chl a concentration in intertidal waters has been little studied using ocean color remote sensing so far.…”