Premium
The production‐to‐respiration ratio and its implication in Lake Biwa, Japan
Author(s) -
Urabe Jotaro,
Yoshida Takehito,
Gurung Tek Bahadur,
Sekino Tatsuki,
Tsugeki Narumi,
Nozaki Kentaro,
Maruo Masahiro,
Nakayama Eiichioro,
Nakanishi Masami
Publication year - 2005
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/s11284-005-0052-y
Subject(s) - plankton , primary production , bacterioplankton , environmental science , total organic carbon , heterotroph , benthic zone , carbon cycle , carbon sink , respiration , biomass (ecology) , carbon dioxide , environmental chemistry , mineralization (soil science) , ecology , sink (geography) , carbon fibers , oceanography , ecosystem , phytoplankton , chemistry , biology , geology , nutrient , soil science , botany , geography , genetics , soil water , cartography , bacteria , materials science , composite number , composite material
Production‐to‐respiration (P:R) ratio was estimated at an offshore site of Lake Biwa in order to examine whether the plankton and benthic community is subsidized with allochthonous organic carbon, and to clarify the role of this lake as potential source or sink of carbon dioxide. The respiration rate of protozoan and metazoan plankton was calculated from their biomass and empirical equations of oxygen consumption rates, and that of bacterioplankton was derived from their production rate and growth efficiency. In addition, the carbon mineralization rate in the lake sediments was estimated from the accumulation rate of organic carbon, which was determined using a 210 Pb dating technique. On an annual basis, the sum of respiration rates of heterotrophic plankton was comparable to net primary production rate measured by the 13 C method. However, when the mineralization rate in the lake sediments was included, the areal P:R ratio was 0.89, suggesting that Lake Biwa is net heterotrophic at the offshore site with the community being subsidized with allochthonous organic carbon. Such a view was supported by the surface water pCO 2 that was on average higher than that of the atmosphere. However, the estimate of net CO 2 release rate was close to that of carbon burial rate in the sediments. The result suggests that the role of Lake Biwa in relation to atmospheric carbon is almost null at the offshore site, although the community is supported partially by organic carbon released from the surrounding areas.