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Zooplankton Dynamics in the Hyper‐Eutrophic Nakdong River System (Korea) Regulated by an Estuary Dam and Side Channels
Author(s) -
Kim Hyun Woo,
Joo Gea Jae,
Walz Norbert
Publication year - 2001
Publication title -
international review of hydrobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 1434-2944
DOI - 10.1002/1522-2632(200101)86:1<127::aid-iroh127>3.0.co;2-f
Subject(s) - zooplankton , estuary , tributary , plankton , biomass (ecology) , environmental science , phytoplankton , eutrophication , oceanography , abundance (ecology) , ecology , fishery , biology , geography , geology , nutrient , cartography
Zooplankton in the main channel of the Nakdong River and in three tributaries was sampled from June 1994 to September 1995. Planktonic rotifers ( Brachionus spp., Keratella spp., and Polyarthra spp.), cyclopoid nauplii and small cladocerans ( Bosmina longirostris ) were numerically dominant. There was considerable longitudinal variation of zooplankton biomass in the main channel as well as spatial heterogeneity among the major tributaries. In the middle region of the main channel, between river kilometer (RK) 170 and 150 above the estuary dam, total zooplankton abundance sharply increased from less than 100 ind. L —1 to more than 1,000 ind. L —1 . In a downstream direction toward the estuary dam, phytoplankton biomass increased while total zooplankton biomass decreased. However, as shown by the increasing transport of zooplankton biomass, zooplankton was diluted in the reach of the estuary dam. Advective effects from major tributaries appear to be the contributory factor for the higher zooplankton biomass in the middle region. Overall, rather the external factors (flushing, retention) than internal factors (e.g., phytoplankton) appear to be responsible for changes in zooplankton abundance toward the river mouth.