• Korean Journal of Environmental Biology
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• v.42 no.2
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• pp.207-218
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• 2024

Food webs have received global attention as next-generation biomonitoring tools; however, it remains challenging because revealing trophic links between species is costly and laborious. Although a link-extrapolation method utilizing published trophic link data can address this difficulty, it has limitations when applied to construct food webs in domestic streams due to the lack of information on endemic species in global literature. Therefore, this study aimed to develop a link extrapolation-based food web model adapted to Korean stream ecosystems. We considered taxonomic similarity of predation and dominance of generalists in aquatic ecosystems, designing taxonomically higher-level matching methods: family matching for all fish (Family), endemic fish (Family-E), endemic fish playing the role of consumers (Family-EC), and resources (Family-ER). By adding the commonly used genus matching method (Genus) to these four matching methods, a total of five matching methods were used to construct 103 domestic food webs. Predictive power of both individual links and food web indices were evaluated by comparing constructed food webs with corresponding empirical food webs. Results showed that, in both evaluations, proposed methods tended to perform better than Genus in a data-poor environment. In particular, Family-E and Family-EC were the most effective matching methods. Our model addressed domestic data scarcity problems when using a link-extrapolation method. It offers opportunities to understand stream ecosystem food webs and may provide novel insights into biomonitoring.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.435-436
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• 2001

In sand beaches the benthic macrofauna feeding on primary food sources such as detritus and phytoplankton and being prey in turn for top predators such as fishes occupies a key position in the center of food chains. Amphipods are the most productive bentho-pelagic animals (Barnard, 1963) and are commonly consumed by fishes and larger crustaceans (Vetter, 1995). Consequently, amphipods play an important role in energy flow as a trophic link from primary producers to higher consumers(Chiaravalle et al., 1997).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.380-389
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• 2007

Stable carbon and nitrogen isotopes were analyzed in suspended particulate organic matter, macroalgae and macrobenthic invertebrates in order to determine the importance of primary organic matter sources in supporting food webs of rocky subtidal and intertidal macroalgal beds in the Korean coasts. Investigations were conducted at the inter tidal sites within Gwangyang bay, a semi-enclosed and eutrophicated bay, and the subtidal sites of the east coast, a relatively oligotrophic and open environment, in May and June 2005. Water-column suspension feeders showed more negative $\delta^{13}C$ values than those of the other feeding guilds, indicating trophic linkage with phytoplankton and thereby association with pelagic food chains. In contrast, animals of the other feeding guilds, including interface suspension feeders, herbivores, deposit feeders, omnivores and predators, displayed relatively less negative $\delta^{13}C$ values than those of the water-column suspension feeders and similar with that of macroalgae, indicating exclusive use of macroalgae-derived organic matter and association with benthic food chains. Most the macrobenthic species were considered to form strong trophic links with benthic food chains. In addition, the distribution of higher $\delta^{15}N$ values in macrobenthic consumers and macroalgae at the intertidal sites of Gwangyang Bay than those at the subtidal sites of the east coast suggests that anthropogenic nutrients may enhance the macroalgal production at the intertidal sites and in turn be incorporated into the particular littoral food web in Gwangyag Bay. These results confirm the dominant role of macroalgae in supporting rocky subtidal and intertidal food webs in the Korean coasts.

• The Korean Journal of Ecology
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• v.19 no.6
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• pp.543-562
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• 1996

Zooplankton community structure and the factors correlated with community differences were examined in sandusky Bay (SB) and the open water of Lake Erie (LE, U.S.A.). SB zooplankton communities differed from those in LE by having a greater rotifer density and species richness. Keratella spp., Brachionus spp., and Pompholyx complanata dominated SB rotifers; Brachionus and Pompholyx were rarely seen in LE. Of 19 rotifer species observed, nine species were found only at SB sites. Ordination of zooplankton species abundance by detrended correspondence analysis (DCA) showed an overlap between SB and LE sites, but indicated a portion of the space that was occupied by only SB communities. The seasonal trajectories of zooplankton dynamics in the ordination space at SB sites differed from that of LE. The zooplankton most important in forcing site separation along a DCA Axis I at SB sites were Brachionus angularis, Pompholyx complanata, Keratella valga, Keratella quadrata, Filinia terminalis (rotifers), and Eubosmina coregoni and Daphnia (cladocerans). These species had axis scores which were significantly correlated (p<0.01) with bacterial density and bacterial phosphorus, total phosphorus, and algal density. Very high baterial density and very abundant bacterivorous rotifers in SB suggest that the transport of bacterial carbon through rotifers may be a relatively important link to higher trophic leaels. We believe that this "microbial carbon flow" from the base of the food web may be important in determining the suitability of SB as a spawning site and nursery for larval and juvenile fish.nile fish.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.424-434
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• 2006

This study investigates bacteria-zooplankton grazing link and factors affecting their grazing relationship at trophically different two sites (Paldang Dam and Kyungan Stream) of Lake Paldang Ecosystem from April to December, 2005. Zooplankton were divided into two size groups; microzooplankton (MICZ) : 60-200 ${\mu}m$ and macrozooplankton (MACZ): >200 ${\mu}m$), and their grazing rates on bacteria were conducted for each size group separately. Bacterial abundance and seasonal change pattern were similar between two sites. MICZ, mostly rotifers (e.g., Brachionus, Keratella, Polyathra) were numerically dominant at both sites, while carbon biomass was highest in cladocerans. Zooplankton biomass was higher at the Kyungan Steam site compared to Paldang Dam site, and their high biomass during spring decreased as they were passing through the storm events in summer season at both sites. Zooplankton clearance rate (CR) was high in spring and autumn while low in summer at Paldang Dam site. However, zooplankton CR was high during the summer at Kyungan Stream site. Bacterial C-flux was high in spring and autumn when MACZ (esp. cladecerans) developed at a high biomass level at both sites. Overall, MACZ community CR and carbon flux (C-flux) were higher than those of MICZ, and the degree of difference between them was higher at Kyungan Stream site. Short hydraulic residence time and physical disturbance caused by summer storm event appeared to affect the zooplankton grazing on bacteria at both sites. The results of this study indicate that bacteria are potentially important carbon source of zooplankton, and that both biotic (e.g,, prey and predator taxa composition and abundance) and physical parameters appear to alter energy transfer in the planktonic food web of this river-reservoir hybrid system.

• Ocean and Polar Research
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• v.29 no.4
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• pp.401-410
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• 2007

In Korea the study of marine heterotrophic protists started in the late 1980s, and since the early 1990s many studies have been conducted in various marine environments. In this article, studies on the distribution and abundance of protists and the biotic interactions(bacteria-protists, phytoplankton-protists) conducted in Korean coastal waters are reviewed, and a field study is reported and discussed. The field study in Masan Bay was carried out from February 2004 to November 2005 at seven selected stations representative of the bay. During the study, the mean abundance of heterotrophic bacteria and the mean concentration of chlorophyll-a were $2.1{\times}10^6\;cells\;mL^{-1}$ and $9.8{\mu}g\;L^{-1}$, respectively. Heterotrophic protists consisted of heterotrophic dinoflagellates, heterotrophic nanoflagellates(excluding dinoflagellates) and ciliates, and their abundances were means of $7.9{\times}10^4\;cells\;L^{-1}$, $1.2[\times}10^3\;cells\;mL^{-1}$, and $4.0{\times}10^4\;cells\;L^{-1}$, respectively. Generally, the chlorophyll-a concentra+CZ14tions and the abundances of heterotrophic bacteria and protists were higher in the inner zone of the bay, where there are high concentrations of organic matters, than in the middle and outer zones. Using the grazing rates of heterotrophic nanoflagellates on bacteria previously reported in this area, it can be calculated that about 69% of bacterial producton was removed by HNF grazing activity. About 24% of initial chlorophyll-a concentration was removed by microzooplankton grazing activity. In conclusion, this study suggests that in Masan Bay heterotrophic protists control the growth of bacteria and phytoplankton, and heterotrophic protists represent an important link of bacterial & microalgal biomass to higher trophic levels.