• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.340-346
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• 2012

The relationships between environmental factors and the dynamics of the microcrustacean community, including planktonic or epiphytic cladocerans and copepods, were studied at Upo Wetlands from 2001 to 2010. Among 10 identified cladoceran taxon, epiphytic cladocerans (Alona, Camptocercus, Simocephalus, Diaphanosoma, Sida) and planktonic cladocerans (Bosmina, Ceriodaphnia, Daphnia, Moina, Scapholeberis) showed distinctive patterns in appearance throughout the year. Overall, epiphytic cladocerans were more abundant during the aquatic plant development season (May to Nov.), planktonic cladocerans were similarly distributed throughout the seasons, but showed a lower density than epiphytic cladocerans. The seasonal changes in copepods abundance showed a similar seasonal pattern when compared to epiphytic cladocerans. Planktonic cladocerans showed no significant relationship to rainfall and physico-chemical factors, while epiphytic cladocerans exhibited a distinct relationship with rainfall and water temperature (n=120, p<0.01), and a negative relationship with pH and conductivity (n=120, p<0.05). Among the epiphytic cladocerans, the Alona and Diaphanosoma showed a distinctive correlation with environmental factors, and their density was affected by rainfall and water temperature (n=120, p<0.01). Copepods had a positive relationship with rainfall (n=120, p<0.01) and water temperature (n=120, p<0.05). In conclusion, changes in rainfall and water temperature can affect the seasonal changes of microcrustacean community and abundance in Upo Wetlands.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.86-93
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• 2013

We monitored 32 wetlands in order to investigate the influence of aquatic plants on zooplankton density and diversity in the littoral zone in Gyeongsangnam-do from May to June in 2011. A total of 65 zooplankton species were identified in the study sites. Among them, the diversity of epiphytic zooplankton were higher (40 species) than planktonic zooplankton. Littoral zones of all wetlands were covered by various aquatic plants, and influenced the epiphytic zooplankton assemblages. Based on the data from $1{\times}1$ (m) quadrat sampling, epiphytic and planktonic rotifer density showed no significant relationships with macrophyte cover. However, the epiphytic cladocerans density significantly increased under high aquatic plant cover ($r^2=0.39$, p<0.05, n=32). Types of aquatic plants strongly influenced epiphytic zooplankton density. Upo and Jangcheok are locations which have well developed Phragmites communis and Ceratophyllum demersum communities in the littoral zone, and a higher density of epiphytic zooplankton was recorded on the surface of C. demersum. Especially, rotifers such as Lepadella, Monostyla and Testudinella showed obvious differences (One-way ANOVA, p<0.05 for all three species). This result suggests that epiphytic zooplankton have a substrate preference for larger surface areas, likely for adherence, on C. dimersum. In conclusion, the complex structure of the littoral plant community is expected to provide diverse refuge and microhabitats to epiphytic zooplankton.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.133-143
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• 2015

Freshwater macrophytes improve the structural heterogeneity of microhabitats in water, often providing an important habitat for zooplankton. Some studies have focused on the overall influence of macrophytes on zooplankton, but the effects of macrophyte in relation to different habitat characteristics of zooplankton (e.g., epiphytic and pelagic) have not been intensively studied. We hypothesized that different habitat structures (i.e., macrophyte habitat) would strongly affect zooplankton distribution. We investigated zooplankton density and diversity, macrophyte characteristics (dry weight and species number), and environmental parameters in 40 shallow wetlands in South Korea. Patterns in the data were analyzed using a self-organizing map (SOM), which extracts information through competitive and adaptive properties. A total of 20 variables (11 environmental parameters and 9 zooplankton groups) were patterned onto the SOM. Based on a U-matrix, 3 clusters were identified from the model. Zooplankton assemblages were positively related to macrophyte characteristics (i.e., dry weight and species number). In particular, epiphytic species (i.e., epiphytic rotifers and cladocerans) exhibited a clear relationship with macrophyte characteristics, while large biomass and greater numbers of macrophyte species supported high zooplankton assemblages. Consequently, habitat heterogeneity in the macrophyte bed was recognized as an important factor to determine zooplankton distribution, particularly in epiphytic species. The results indicate that macrophytes are critical for heterogeneity in lentic freshwater ecosystems, and the inclusion of diverse plant species in wetland construction or restoration schemes is expected to generate ecologically healthy food webs.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.332-342
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• 2013

We collected zooplankton from May to October, 2011, with the aim of understanding the zooplankton community distribution and food web interaction between the open water and littoral (aquatic plants) zones in two small reservoirs with different land covers (Sobudang, Myeongdong). Small-sized reservoirs are more abundant in South Korea, and a total of 51 and 65 species of zooplankton were identified at the two small reservoir (Sobudang and Myeongdong), where zooplankton densities were more abundant in the littoral zone than in the open water zone. Cladocerans and copepods densities were also higher in the littoral zone, in contrast, rotifers showed higher densities in the open water zone (t-test, P/0.05). Epiphytic zooplankton dominated at the littoral zone (Lecane, Monostyla, Alona and Chydorus) because aquatic plants provided refuge spaces for attachment. Some rotifers (e.g. Brachionus, Keratella and Polyarthra) were more abundant in the open water zone because of their small size, which might help them to go unnoticed by predators. In two-way ANOVA, rotifers related to two reservoirs or habitat space (littoral zone and open water zone), but cladocerans and copepods showed a statistically significant relationship on only two reservoirs. The results of stable isotope analysis showed that zooplankton in the littoral zone tended to depend on organic matter attached to aquatic plants as a food source, which indicates the avoidance of competition of zooplankton with other macro-invertebrates (e.g. Damselfly larva, Cybister brevis and Neocardina denticulate). As a result, zooplankton community distribution is determined by not only habitat space (aquatic plant zone and open water zone) but also by food source (phytoplankton).