TY - JOUR AU - Choi, Jong-Yun AU - Jeong, Kwang-Seuk AU - La, Geung-Hwan AU - Joo, Gea-Jae PY - 2014/10/08 Y2 - 2024/03/28 TI - Spatio-temporal distribution of Diaphanosoma brachyurum (Cladocera: Sididae) in freshwater reservoir ecosystems: importance of maximum water depth and macrophyte beds for avoidance of fish predation JF - Journal of Limnology JA - J Limnol VL - 74 IS - 2 SE - Notes DO - 10.4081/jlimnol.2014.1053 UR - https://www.jlimnol.it/jlimnol/article/view/jlimnol.2014.1053 SP - AB - In empirical studies, Cladocera is commonly utilized as a primary food source for predators such as fish, thus, predator avoidance are important strategies to sustain their population in freshwater ecosystems. In this study, we tested the hypothesis that water depth is an important factor in determining the spatial distribution of <em>Diaphanosoma</em> <em>brachyurum</em> LiƩvin, 1848 in response to fish predation. Quarterly monitoring was implemented at three water layers (<em>i.e.</em>, water surface and middle and bottom layers) in 21 reservoirs located in the southeastern part of South Korea. <em>D. brachyurum</em> individuals were frequently observed at the study sites and exhibited different spatial patterns of distribution in accordance with the maximum depth of the reservoirs. In the reservoirs with a maximum depth of more than 6 m, high densities of <em>D. brachyurum</em> were observed in the bottom layers; however, in the shallower reservoirs (maximum depth &lt;6 m), <em>D. brachyurum</em> were concentrated in the surface layer. Moreover, during additional surveys, we observed a trend in which <em>D. brachyurum</em> densities increased as the maximum depth or macrophyte biomass increased. Gut contents analysis revealed that predatory fishes in each reservoir frequently consumed <em>D. brachyurum</em>; however, the consumption rate abruptly decreased in reservoirs where the maximum depth was more than 11 m or in the shallow reservoirs supporting a macrophyte bed. Interestingly, the reservoirs more than 11-m depth supported high densities of <em>D. brachyurum </em>in the bottom layer and in the surface macrophyte bed. Based on these results, reservoirs with a maximum depth of more than 11 m or those with a macrophyte bed may provide a refuge for <em>D. brachyurum</em> to avoid fish predation. Compared with other cladoceran species, <em>D. brachyurum</em> readily exploits various types of refugia (in this study, the deep layer or surface macrophyte bed), which may help explain why this species is abundant in various types of reservoirs. ER -