하천 생태학의 발전과 우리나라 하천 연구의 현황

주기재,김현우,하경,Joo, Gea-Jae,Kim, Hyun-Woo,Ha, Kyong 한국생태학회 1997 Journal of Ecology and Environment Vol.20 No.1

The development of stream ecology, especially the progress of that field in North America, has been briefly reviewed, and stream studies in Korea were analyzed through literature survey. During the last two decades, theoretical advances in stream ecology and understanding of the structure and function of stream ecosystem were made from the studies mainly in North America. Early studies (1960-1970) focused on determination of the environmental factors controlling the distribution and abundance of organisms dwelling in streams. Introduction of conceptual development, such as the functional feeding concept, river continuum concept, and nutrient spiraling was notable in the late 70's and the 80's. For last 20 years, experimentation approaches to apply ecological principles were very fruitful in the understanding of community structure. Even though studies on the stream ecosystem is Korea have a long history, most of works were concentrated on limited subjects: water quality, abundance and distribution of aquatic insects and fishes. Basic ecological attributes of stream organi는 and test of ecological principles have rarely been a subject of research topics. We must concentrate our effort to enhance our understanding of stream and river ecosystem through qualitative, experimental and interdisciplinary approaches.

동물플랑크톤 배양여과액에 의한 Microcystis aeruginosa의 성장, 형태 및 microcystin 생성량의 변화

하경 ( Kyong Ha ),장민호 ( Min Ho Jang ),정종문 ( Jong Mun Jung ),주기재 ( Gea Jae Joo ) 한국하천호수학회 2003 생태와 환경 Vol.36 No.1

Growth, colony formation and microcystin production of `low-toxic` Microcysits aeruginosa Ku¨tzing were examined in relation to the `info-chemicals` released by zooplankton. Algae were cultured in a medium with or without filtered water taken from cultures of Daphnia magna Straus(300 ind./L) or Moina macrocopa Straus (500 ind./L). The growth of M. aeruginosa, based on cell number, was also significantly different from populations cultured in the media with and without filtered zooplankton water from the exponential growth phase. In the 6-days experiment, the growth pattern of M. aeruginosa cultured with ZCMF was clearly different to control without ZCMF. Mean number of cells/particle and particle bio-volume of M. aeruginosa increased significantly from the day 2 for the Daphnia-CMF or Moina-CMF treatments. Microcystin production was promoted showing from 18.7 to 44 ㎍/g-dry cell in the zooplankton treatments relative to the controls. At peaked level on day 4, the highest level of up to 70.5±16.8㎍/g-dry cell was observed in the D. magna treatment. This study suggested that `info-chemicals` from zooplankton might induce the increase of algal growth rates, colony formation and microcystin production, these seem to be advantageous to the alga and thus as a grazing defense mechanism.

부산·경상남도의 상류하천의 물리·화학적 특성과 부착조류 생체량의 분포

하경,박성배,김현우,김진수,주기재 ( Kyong Ha,Sung Bae Park,Hyun Woo Kim,Jin Soo Kim,Gea Jae Joo ) 한국하천호수학회 1997 생태와 환경 Vol.30 No.4

Physicochemical characteristics and chlorophyll-a distribution of the epilithon at the 12 sites of 6 headwater streams in Pusan and Kyongsangnam-do province studied bimonthly from April 1994 to March 1995. Even though all study sites shawed softwater nature, the basic limnological parameters showed wide ranges of variation (alkalinity. 6∼16 mgCaCO_3/l; conductivity, 30∼76μS/cm: pH, 6.4∼7.3: TN, 0.5∼2.1 mg/l; TP. 64∼312㎍/l, n=12). Generally, low chlorophyll-a (4.8±1. 1 mg/m^2) was observed from 1st and 2nd order streams, whereas higher chlorophyll-a (22. 1 ±11.5 mg/m^2) was observed from larger streams. The chlorophyll-a in the summer (7.4±5.1 mg/m^2) was lower than that of the winter (14.2±14.5 mg/m^2) due to precipitation and riparian vegetation. Larger streams with high light input tended to have higher chlorophyll-a.

Growth and Morphological Changes in Scenedesmus dimorphus Induced by Substances Released from Grazers, Daphnia magna and Moina macrocopa

Ha, Kyong,Jang, Min-Ho,Joo, Gea-Jae,Noriko Takamura 한국육수학회 2001 생태와 환경 Vol.34 No.4

상위포식자에 의해 유도되는 Scenedesmus dimorphus (Tu¨rpin) Ku¨tzing의 군체형성에 관한 실험을 수행하였다. 동물플랑크톤 Daphnia magna (300 ind./L)와 Moina macrocopa (500 ind./L) 배양한후 0.1㎛(millipore)로 여과하여 얻어낸 용액 (ZFW)을 S. dimorphus가 108(10^5 cells/ml까지 자란 처리군에 첨가하여, ZFW를 넣지않은 대조군과 비교하였다. 대조군에 비해 두 동물플랑크톤 처리군에서 S. dimorphus의 군체형성의 유도가 뚜렷이 관찰되었다. 이 현상은 M. macrocopa 보다는 D. magna처리군에서 뚜렷하게 관찰되었으며, 첨가해준 ZWF의 양이 증가할수록 particle당 세포수도 비례적으로 증가하는 것으로 나타났다. ZFWCJFLRNS에서 1군체당 세포수(cell/colony)와 평균체적(mean particle biovolume)은 24∼72시간 사이에 급격히 증가하는 것으로 관찰되었다. S. dimorphus의 군체형성현상은 동물플랑크톤 D. magna와 M. macrocopa의 분비물에서 유도되는 화학물질의 영향으로 보이며, 이와 같은 형태변화현상은 동물플랑크톤의 포식에 대한 방어기작으로 작용하게 될 것으로 사료된다. Grazer-induced colony formation was examined using a green alga Scenedesmus dimorphus (Tu¨rpin) Ku¨tzing. Algae were cultured in a medium with or without filtered water taken from cultures of Daphnia magna Straus (300 ind./L) or Moina macrocopa Straus (500 ind./L). The exposure to zooplankton filtered water(ZFW) promoted colony formation in S. dimorphus, with the magnitude of this response being directly proportional to the relative volume of ZFW that was added to the culture medium. The number of cells/colony and mean particle biovolume of S. dimorphus increased between 24 and 72 hours after exposure to ZFW, most likely due to the influence of chemicals released from D. magna or M. macrocopa, and possibly as a defense mechanism against zooplankton grazing.

pH , 영양염류 농도 및 빛이 Microcystis bloom 의 초기단계에 미치는 영향

하경,장민호,정광석,박재림,주기재 한국환경과학회 2002 한국환경과학회지 Vol.11 No.7

In order to determine the factors causing Microcystis spp. bloom in the lower Nakdong River (Mulgum), we prepared wide ranges of pH, nutrient(N, P) concentration and the light through an enclosure experiment for 10 days (pH gradient: 6.5, 7.5, 8.5, 9.5; gradient of N, P: 1/2DW+1/2River Water (RW), RW only; four different levels of nutrient addition/day; light: 100, 85, 60, 30, 15% of full sun light). From three days, the difference of Microcystis density in each enclosures was observed. The high density of Microcystis was maintained in the treatments over pH 9.5 and 85% of full sun light. However, in all nutrient treatments, relatively lower cell density than that of pH and light treatments was observed. These results suggested that pH and light input may play more important roles than nutrients in the early development of Microcystis bloom in the eutrophic lower Nakdong River.

상류하천에서의 인공저층을 이용한 부착조류의 생체량 측정을 위한 노출기간 평가

김현우,하경,주기재 한국환경과학회 1998 한국환경과학회지 Vol.7 No.1

During the spring and fall of 1994 and winter of 1995, the exposure time of periphyton biomass on the artificial substrata at 10 headwater streams in the southeastern Korea was evaluated in 7-14 day interval. In the streams with low periphyton biomass (chl a: 2-4 ㎎/㎡) in natural rocks, biomass of artificial substrata (unglazed the: 3.7 × 9.5 × 2 ㎝) exceeded that of the natural rocks after 28 days, while sites with high biomass (chl. a: 20-60 ㎎/㎡) in natural rocks showed slower biomass accumulation after 40 days. Due to the high light input and temperature in a partially shaded mountain stream, development of periphyton biomass in spring occurred faster than that of winter. In general, development of periphyton biomass placed on artificial substrata took 4-5 weeks in spring and at least 6 weeks in winter to reach the natural level.

낙동강 중 , 하류에서 식물플랑크톤과 세균의 계절적 동태

박재림,하경,손연주,주기재 한국환경과학회 2001 한국환경과학회지 Vol.10 No.4

Investigations were carried out to observe the seasonal succession of phytoplankton, and viable counts of bacteria from the mid to lower reaches of Nakdong River. An intensive monitoring was conducted from May to December 1999 biweekly at 6 sites in a main channel and 3 tributaries. Although there are several sites with high nutrient loading from the basin, all of study sites showed mesotrophic states owing to high discharge(June∼September). Relatively low algal biomass and CFUs(mean of chl. a, 12.3±11.5 ㎍/ℓ, CFUs : 1.8×10 exp (7)) were observed during the rainy season. The diatom population was dominant(over 85% of total community) year-long with peaks (Stephanodiscus hantzschii) in the fall and winter. Dominance of blue-green algal groups during the summer was not observed in the summer. Microorganisms peaked in the summer and fall (June∼September), affected mainly by the inputs of phytoplankton and nutrients. Biomass of phytoplankton and CFU counts were higher in the Kumho River than the other tributaries and main channel.