• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.515-524
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• 2019

The purpose of this study is to investigate the effects of artificial disturbance by analyzing and comparing the survey data of the Yeongju dam located in Yeongju-si, Gyeongbuk before and after impoundment. We surveyed four sites between the downstream of sediment control to the downstream of Yeongju Dam four times between April and October 2018. The macroinvertebrate data before the survey were gathered from the literature. The total number of benthic macroinvertebrates we observed was $35,037ind./m^2$, including 77 species, 48 families, 14 orders, 7 classes, and 3 phyla. The result of the community analysis showed that the dominant index increased from 0.44(${\pm}0.11$) before impoundment to 0.62(${\pm}0.16$) after impoundment. The diversity index increased from 2.26(${\pm}0.30$) to 1.75(${\pm}0.45$), the evenness index from 0.75(${\pm}0.10$) to 0.66(${\pm}0.14$), and the richness index from 3.11(${\pm}0.98$) to 2.25(${\pm}0.81$). The most dominant species changed from Hydropsychidae spp. to Chironomidae sp. The result of the Principal Components Analysis (PCA) based on Axis 1 showed that the sites of 2014 and Hydropsychidae spp. had a negative value, while the sites of 2018 and Chironomidae sp. had a positive value. In all study sites, the dominance increased while the diversity decreased. The community change was the largest in St. 2. The results of the functional group analysis showed that the scrapers increased while gathering-collectors increased among the functional feeding group and that the clingers decreased while borrows increased among the habitat oriented group. The Benthic Macroinvertebrate Streambed Index (BMSI) decreased from an average of 57.1(${\pm}8.0$, C class) to an average of 30.0(${\pm}12.1$, C class). St. 3 and St. 4, in particular, showed a high reduction rate.

• Korean Journal of Ichthyology
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• v.3 no.1
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• pp.1-10
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• 1991

Spawning behavior and development of eggs and larvae of Mugilogobius abei were observed in the laboratory at Pusan, Korea. The adult male of Mugilogobius abei was observed making nest-like spawning-bed to lay eggs and showing territorial and courtship behaviors. The eggs were transparent and spherical in shape, measuring 0.40~0.50 mm in diameter. They have a bundle of adhesive filaments at their basal end and a cluster of small oil globules. The eggs became ellipsoid shape after the insemination and measured about 0.93~0.96 mm on the long axis. Hatching began about 110 hours after fertilization at water temperature of $24.5{\sim}25.5^{\circ}C$. The newly hatched larvae were 2.04~2.10 mm in total length, with 24~25(8~9+16) myomeres. Many melanophore and guanophore are distributed on eye cups, gas bladder, optic vesicle and the caudal region. Four days after hatching the yolk and oil-globule were completely absorbed and the larvae attained a total length 2.20~2.35 mm. The larvae swam actively in the aquarium and start to practice feeding on the rotifer. Twelve days after hatching, the larvae averaged 3.20 mm in TL and the caudal notochord flex at $45^{\circ}$. Rudimental second dorsal, anal, caudal and ventral fins are also formed. The larvae attained 10.40~10.80 mm in TL, 35 days after hatching, are found to start the bottom-life after having completely formed first dorsal and ventral fins. The larvae reached the juvenile stage at 50~60 days after hatching and attained 15.37~20.25 mm in TL. At this period all scales appeared on the body.