Effects of filter-feeding bivalves on the distribution of water quality and nutrient cycling in a eutrophic coastal lagoon

Citation
Y. Nakamura et F. Kerciku, Effects of filter-feeding bivalves on the distribution of water quality and nutrient cycling in a eutrophic coastal lagoon, J MAR SYST, 26(2), 2000, pp. 209-221
Citations number
20
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
JOURNAL OF MARINE SYSTEMS
ISSN journal
09247963 → ACNP
Volume
26
Issue
2
Year of publication
2000
Pages
209 - 221
Database
ISI
SICI code
0924-7963(200010)26:2<209:EOFBOT>2.0.ZU;2-X
Abstract
The horizontal variation of water quality was investigated through field su rveys in a cross-section of Lake Shinji, the littoral region of which is de nsely populated by the filter-feeding bivalve, Corbicula japonica. The dist ributions of chlorophyll a (chl. a) and nutrients (NH4-N and PO4-P) in the lake are greatly affected by the filtration and excretion rates of C. japon ica. Minimum values for chi. a and maximum values for nutrients were both f ound to occur in the littoral region during summer. Chi. a concentration pe aked about 1 km from the shoreline, indicating that the presence of the biv alve not only reduces the biomass of phytoplankton in the near shore region through filtration, but also stimulates primary production further offshor e by supplying nutrients through excretion. Calculated results of a mathema tical model reproduced well the observed horizontal distributions of chi. a and nutrients, indicating that the interaction between the filter-feeding bivalve and phytoplankton populations dominates material cycling and water quality distribution in the lake. Water mass exchange between littoral and pelagic water enables the nutrient exchange between the bivalves in the ben thic zone and the phytoplankton in the pelagic zone, thereby forming a bent hic-pelagic zone coupling. Other related findings were that seasonal patter ns of water quality variations in the north-south cross-section were affect ed by metabolic rates of C. japonica, and that differences in concentration s between pelagic and littoral regions are largest when water temperature i s optimal for bivalve activity. (C) 2000 Elsevier Science B.V. All rights r eserved.