• Title/Summary/Keyword: Mesocosm

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Application of Enclosed Experimental Ecosystem to the Study on Marine Ecosystem (해양생태계 연구를 위한 폐쇄생태계의 활용)

  • 김웅서
    • Korean Journal of Environmental Biology
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    • v.19 no.3
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    • pp.183-194
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    • 2001
  • As researchers can modify environmental factors to fit the purpose of an experiment in monitoring marine ecosystem using enclosed experimental ecosystems, which is a strong advantage of them, mid-sized enclosed experimental ecosystems (mesocosm) are widely used in the world in basic ecology such as trophodynamic study and applied ecology such as the toxicity test of various chemicals and monitoring of ecosystem changes against marine pollution. Application of the mesocosm in the field has a merit to get more reliable result than that from the experiment in the laboratory. However, the result from the mesocosm study in marine ecosystem is very limited in Korea. Mesocosms which had been used in the marine ecological studies in both foreign countries and Korea were summarized, and application of them to the future study in various research field was suggested in this review paper.

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A continuous-flow and on-site mesocosm for ocean acidification experiments on benthic organisms

  • Kim, Ju-Hyoung;Kang, Eun Ju;Kim, Keunyong;Kim, Kwang Young
    • ALGAE
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    • v.33 no.4
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    • pp.359-366
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    • 2018
  • Mesocosm experiments conducted for ecological purposes have become increasingly popular because they can provide a holistic understanding of the biological complexities associated with natural systems. This paper describes a new outdoor mesocosm designed for $CO_2$ perturbation experiments of benthos. Manipulated the carbonate chemistry in a continuous flow-through system can be parallelized with diurnal changes, while irradiance, temperature, and nutrients can vary according to the local environment. A target hydrogen ion activity (pH) of seawater was sufficiently stabilized and maintained within 4 h after dilution, which was initiated by the ratio of $CO_2$-saturated seawater to ambient seawater. Specifically, pH and $CO_2$ partial pressure ($pCO_2$) levels gradually varied from 8.05-7.28 and $375-2,691{\mu}atm$, respectively, over a range of dilution ratios. This mesocosm can successfully manipulate the pH and $pCO_2$ of seawater, and it demonstrates suitability for ocean acidification experiments on benthic communities.

Effects of Biological Control Agent Algicidal Bacterium on the Phytoplankton Community and Microcystin-LR Contents in a Mesocosm Experiment (살조세균 적용이 식물플랑크톤 군집과 조류독소 분포에 미치는 영향)

  • Jung, Seung-Won;Seo, Jong-Kun;Suh, Mi-Yeon;Han, Myung-Soo;Kim, Baik-Ho
    • Korean Journal of Ecology and Environment
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    • v.38 no.2 s.112
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    • pp.261-270
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    • 2005
  • Biological control agents (BCA; algicidal bacterium Xantobacter autotrophycus) plus casitone media, strongly changed physicochemical variables, standing crops of phytoplankton and microcystin-LR phytoplankton in 100-L mesocosm constructed in a small hexagonal pond (3.5 m ${\times}$ 5 m). No M. aeruginosa showed by 8 days, and 60% of total standing crops of phytoplanktons were decreased by the BCA treatment. BCA treatment also induced a strong decline of cellular extracted microcystin-LR (MCLR) and a remarkable increase of dissolved MCLR with the decrement in standing crops of cyanobacteria. In addition, BCA strongly increased all nutrients, but new outbreak of phytoplanktons hardly showed in the experimental mesocosm. The field application of BCA to controling the cyanobacterial bloom in large lakes and reservoirs is not relevant due to high concentration of nutrients and toxins. Thus, a further study is needed to diminish the adverse effects after BCA treatment for water quality preservation.

Evaluation of Fertilizer Additions to Stimulate Oil Biodegradation in Sand Seashore Mesocosms

  • CHOI, SUNG-CHAN;KAE KYOUNG KWON;JAE HAK SOHN;SANG-JIN KIM
    • Journal of Microbiology and Biotechnology
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    • v.12 no.3
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    • pp.431-436
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    • 2002
  • Effects of fertilizer additions for oil degradation were examined in sand seashore mesocosms. Within 37 days, up to $85\%$ removal was achieved by the addition of slow-release type fertilizer (SRF) with the initial degradation rate of 423.3 mg oil $(kg sand)^-1\;day^-1$. The removal was mostly of biological origin based on the changes of $C_17$ /pristane and $C_18$/phytane ratios from 2.60 to 0.81 and from 3.55 to 1.29, respectively. The addition of oleophilic fertilizer (Inipol EAP22) was less effective and resulted in the removal of $64\%$ of the added oil ($3\%$, v/v) with a lower initial degradation rate. Petroleum-degrading bacteria had achieved a value of $1{\times}10^8$ CFU $(g sand)^-1$ at Day 3 and this peak exactly coincided with the initial degradation in the SRF-treated mesocosm. In this mesocosm, surface tension values were decreased drastically during Days 3 and 8, suggesting that microbially-produced surface-active agents actively enhanced the oil degradation rate and cell proliferation. Although the Inipol-treated mesocosm appeared to show significantly enhanced oil degradation compared to that of the untreated control mesocosm, Inipol was found to be less effective than SRF in enhancing a true oil-degrader when compared under similar experimental conditions.

The effect of dead coral skeletons on the water quality and sessile mollusks in the closed system (폐쇄시스템 내에서 죽은 산호골격이 수질과 고착성 연체동물에 미치는 영향)

  • Lee, Nam Hyeon;Han, Kyung Nam
    • The Korean Journal of Malacology
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    • v.28 no.3
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    • pp.187-196
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    • 2012
  • Recently, for the purpose of constructing artificial ecosystem, the public aquarium and experimental mesocosm systems are receiving attention. To design and establish an aquarium and mesocosm system, there is need of several materials for simulating the environment, such as sediments, rocks, and plants. Expecially for sessile mollusks, there must be proper materials to which sessile invertebrates can adhere. Nowadays, many aquariums and mesocosm systems are using dead coral skeletons for sessile mollusks. This study was proceeded to have data on the effect of dead coral skeletons on water qualities with the experiment on the environmental factors. For this purpose, I made glass tank for experiment, chose two types of dead coral skeletons imported from the Indonesia and observed the change of water qualities and decomposition efficiency of TAN (total ammonia-nitrogen), nitrite ($NO_2{^-}$) and nitrate ($NO_3{^-}$). As a result, the lager the surface area was, the more TAN, nitrite and nitrate decomposition rate increased. In addition, coral skeletons covered with crustose algae and bacteria in the tank showed faster TAN, nitrite and nitrate removal rate and stabilization. Accordingly, this experiment suggested that dead coral skeletons could be used as a sub filter for the closed system as well as an adhering plate.

Species-specific responses of temperate macroalgae with different photosynthetic strategies to ocean acidification: a mesocosm study

  • Kim, Ju-Hyoung;Kang, Eun Ju;Edwards, Matthew S.;Lee, Kitack;Jeong, Hae Jin;Kim, Kwang Young
    • ALGAE
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    • v.31 no.3
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    • pp.243-256
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    • 2016
  • Concerns about how ocean acidification will impact marine organisms have steadily increased in recent years, but there is a lack of knowledge on the responses of macroalgae. Here, we adopt an outdoor continuous-flowing mesocosm system designed for ocean acidification experiment that allows high CO2 conditions to vary with natural fluctuations in the environment. Following the establishment of the mesocosm, five species of macroalgae that are common along the coast of Korea (namely Ulva pertusa, Codium fragile, Sargassum thunbergii, S. horneri, and Prionitis cornea) were exposed to three different CO2 concentrations: ambient (×1) and elevated CO2 (2× and 4× ambient), over two-week period, and their ecophysiological traits were measured. Results indicated that both photosynthesis and growth exhibited species-specific responses to the different CO2 concentrations. Most notably, photosynthesis and growth increased in S. thunbergii when exposed to elevated CO2 conditions but decreased in P. cornea. The preference for different inorganic carbon species (CO2 and HCO3), which were estimated by gross photosynthesis in the presence and absence of the external carbonic anhydrase (eCA) inhibitor acetazolamide, were also found to vary among species and CO2 treatments. Specifically, the two Sargassum species exhibited decreased eCA inhibition of photosynthesis with increased growth when exposed to high CO2 conditions. In contrast, growth of U. pertusa and C. fragile were not notably affected by increased CO2. Together, these results suggest that the five species of macroalgae may respond differently to changes in ocean acidity, with species-specific responses based on their differentiated photosynthetic acclimation. Understanding these physiological changes might allow us to better predict future changes in macroalgal communities in a more acidic ocean.

Water Quality Improvement with the Application of Filter-feeding Bivalve (Corbicula leana Prime) in a Eutrophic Lake (참재첩을 이용한 부영양호의 수질개선)

  • Kim, Ho-Sub;Park, Jung-Hwan;Kong, Dong-Soo;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
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    • v.37 no.3 s.108
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    • pp.332-343
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    • 2004
  • This study was conducted to test a possibility of water quality improvement using a filter-feeding bivalve (Corbicula leana). In mesocosm scale (width ${\times}$ length ${\times}$ depth: 3 m ${\times}$ 3 m ${\times}$ 0.5 m), we investigated the changes of dissolved nutrient and particulate matter including both abiotic and biotic seston. Short term (16 days) mesocosm experiment was conducted in two stages: the first stage for 8 days and consecutive 8 days of the second stage. Both treatment and control mesocosm were switched over by translocating mussels from the treatment mesocosm to the control, at 8th days since the start of the experiment. This design made it possible to compare mussel effect on the water quality change more clearly. The high mortality of mussel was observed in the treatment of the first stage, but it decreased rapidly and stabilized on the 8th day to less than< 4 ind $day^{-1}$. Chl. a concentration in the treatment mesocosm of the first and second stage decreased to 71 and 88% of initial concentration, respectively, and suspended solids decreased to 70 and 77%. At those times, average filtering rate were 0.46 and 0.61 mL AFDW $mg^{-1}$ $hr^{-1}$, respectively. Both $NH_3-N$ and dissolved total phosphorus (DTP) concentrations increased with the mussel mortality. $NH_3-N$ concentration was positively correlated with the mussel mortality, while DTP concentration showed negative correlation with it. After translocating mussel from the treatment to the control, $NH_3-N$ concentration significantly increased compared with that of initial control. Although DTP concentration also increased, there was no significant difference relative to that of initial control. These results suggest that application of this filter-feeding bivalve in a eutrophic reservoir could be a potential tool to improve water quality if mussels could acclimatize successfully in early stage of the introduction.

Variation of Water Qualities Due to Freshwater Introduction to Tidal Flat: A Mesocosm Study (메조코즘을 이용한 갯벌의 담수화과정 중 수질 변화)

  • Kim Yeong-Tae;Jeong Yong-Hoon;Chae Youn-Ju;Rhee Choong-Won;Kim Soh-Yong;Choi Kang-Won;Yang Jae-Sam
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.11 no.2
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    • pp.49-67
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    • 2006
  • A mesocosm, an artificial tidal flat ecosystem, was constructed outdoors to simulate in situ physical and biochemical environmental conditions of natural tidal flat as much as possible. During the experiment from February to August 2004, the study was focused on the biogeochemical variations of superficial water and porewater after introduction of freshwater into the mesocosm. The mesocosm has three experimental conditions; SW-M-T: maintaining the saline water of approximately 20 psu; FW-M-T: complete exchange of freshwater ul the mesocosm with continuous mixing of water column: FW-NM-T: complete exchange of saline water to freshwater in the mesocosm without mixing of water column. Mass extinction of benthic macrofauna appeared due to drastic decrease of porewater salinity from 20 psu to less than 10 psu between the 63th and 91st day of freshwater introduction in FW-M-T and FW-NM-T. Throughout the periods, 7/8 of bivalves and 2/3 of polychaete populations have been extinguished in the sediment. In FW-NM-T, as temperature rises, both evident decrease of DO in water column and active release of DIP from sediment were observed. ${NO_3}^-$ was removed from water column into sediment throughout the periods. Therefore extremely low ${NO_3}^-$ was found during late spring and summer. Whereas ${NH_4}^+$ exhibited only $1/2{\sim}1/8$ of ${NO_3}^-$ concentration. Unexpectedly even after mass extinction of benthic macrofauna, we were not able to find high ${NH_4}^+$. This mesocosm study suggests that when fresh water introduce to natural tidal flat, its sediment activity functions as a potential source of DIP, but a sink of ${NO_3}^-$.

A Field Application Feasibility of Biologically Derived Substances (Naphthoquinone Derivate: NQ 2-0) for the Mitigation of Harmful Cyanobacterial Blooms (유해 남조류 제어를 위한 생물유래 살조물질 Naphthoquinone 유도체 (NQ 2-0)의 현장 적용 가능성)

  • Joo, Jae-Hyoung;Park, Chong-Sung;Choi, Hye Jeong;Lee, Heon Woo;Han, Myung-Soo
    • Ecology and Resilient Infrastructure
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    • v.4 no.3
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    • pp.130-141
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    • 2017
  • We evaluated the field application feasibility that biologically derived substances (Naphthoquinone derivate: NQ 2-0) can be used for the eco-friendly mitigation of natural harmful cyanobacterial blooms in freshwater. We conducted a 30 ton scale mesocosm experiment to investigate the effects of NQ 2-0 on biotic and abiotic factors in water collected from Gi-heung reservoir. In the mesocosm experiments, the abundance of Microcystis sp. was continuously increased in the control. However, the Microcystis sp. cell density was sharply decreased on the $10^{th}$ day. In the treatment, NQ 2-0 showed the strong and selective algicidal activity toward the target cyanobacteria (Microcystis sp.). Accordingly, the algicidal activity of NQ 2-0 compound increased gradually until $10^{th}$, $15^{th}$ days and algal biomass was decreased to 99.4 and 100 %, respectively. NQ 2-0 compound was not only selective algicidal activity but also the growth of other phytoplankton and increased the Shannon-Wiener diversity index of phytoplankton. In the mesocosm experiments, the dynamics of biotic (bacteria, heterotrophic nanoflagellate, ciliates, zooplankton) and abiotic (water temperature, dissolved oxygen, pH, conductivity, nutrients) factors remained unaffected. These results suggest that NQ 2-0 could be a selective and ecologically safe algicide to mitigate harmful cyanobacterial blooms. In addition, it is believed that NQ 2-0 will play a major role in forming a healthy aquatic ecosystem by facilitating habitat and food supply of aquatic organisms.

Effects of Sediment and Cyanobacterium Microcystis aeruginosa on the Feeding Behavior of Omnivores Gold Fish Carassius auratus (잡식어 붕어의 섭식활동에 퇴적물 및 독성 남조 Microcystis aeruginosa의 영향)

  • Kim, Baik-Ho;Kim, Keun-Hee;Kim, Yong-Jae;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
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    • v.43 no.2
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    • pp.212-220
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    • 2010
  • Effects of sediment and toxic cyanobacterium Microcystis aeruginosa on feeding behaviors of an omnivorous fish, gold fish (Carassius auratus) were examined in laboratory and in situ mesocosm. Laboratory feeding experiments were performed in small aquaria (7 L) with cyanobacterial blooms (mainly M. aeruginosa) under the condition of sediments and no-sediments, and toxic (NIES-298) and non-toxic M. aeruginosa (NIES-101). In situ feeding experiments were conducted at the shore of eutrophic lake (Lake Ilgam, Seoul) in the mid-July, 2005. Results showed that fish introduction decreased the concentration of Chlorophyll-a (Chl-a) at higher rate in no sediment-containing aquaria. In contrast, there was a drastic increase of Chl-a in the sedimentcontaining aquaria. Fish effectively removed the M. aeruginosa cells without algal toxin (microcystin). Fish also selectively removed the large size Chl-a (>$50{\mu}m$), although all kinds of nutrients were increased after fish introduction, especially ammonia. Our results indicate that the strategic introduction of domestic omnivores Carassius auratus, to control cyanobacterial bloom in eutrophic lake will negatively play in the water quality improvement via a sediment disturbance and a density-dependent digestion.