This study investigated the long-term dynamics of phytoplankton communities, key environmental factors, and indicator species in Mulgeum, a major downstream site of the Nakdong River, from 1993 to 2020. Monthly phytoplankton densities ranged from 189 to 52,757,982 cells mL-1, with diatoms dominating yearround (29.1~93.4%). Notably, cyanobacteria exhibited the highest growth rates, which could exacerbate algal blooms under long-term climate change. Using generalized additive models, five environmental factorsdissolved oxygen, transparency, total phosphorus, phosphate, and discharge-were found to significantly influence monthly variations in most taxa. Cyanobacteria were most sensitive to environmental changes, while chrysophytes showed minimal dependence on specific factors. Principal component analysis grouped environmental conditions into five clusters, with each cluster characterized by distinct conditions and indicator species. A total of 122 species were identified as indicators, with green algae contributing the most. Cluster 1, characterized by high transparency and low phosphorus, was dominated by Stephanodiscus hantzschii, a common species in eutrophic waters. Cluster 4, associated with high phosphorus, highlighted Cyclotella ocellata as a key indicator, emphasizing phosphorus as a crucial determinant for diatom structure. These findings underscore the critical role of hydrological and nutrient factors in shaping phytoplankton communities and provide insights into ecological responses to environmental changes in the Nakdong River system. The results can inform sustainable management strategies to mitigate eutrophication.

In this study, in order to develop an eco-friendly filtration method that considers the health and safety of the aquatic ecosystem by differentiating it from chemical methods (coagulants, oxidants, etc.), which are mainly used as methods for managing the removal of algae in the algal bloom stage, an effective separation membrane for algae removal was reviewed, an appropriate technology was proposed through field application, and the effect of algae removal was evaluated. The membrane used was applied in the field by constructing an optimal technology through auxiliary facilities with an immersion tubular membrane and a pressurized tubular membrane resistant to adhesive pollutants and algae. As a result, the strong characteristics of Fouling (blocking) by adhesive algae were confirmed, and the effect of removing algae and particulate matter in the immersion type tubular membrane was 99% chlorophyll-a (Chl-a), 99.2% suspended solid (SS), and 96.7% of pressurized tubular membranes, showing excellent effects in removing algae and particulate organic matter. In addition, as a result of field application to eutrophic reservoirs where high-density algae are distributed, it was confirmed that stable operation of algae was possible during the process of filtering, separation, and concentration.

This study developed an unmanned autonomous moving algae collection device (HAMA-bot) to remove high-density algae concentrated in the waterfront of urban agricultural reservoirs, and analyzed the effect of algae removal after field application to medium-sized urban reservoir. The algae reduction effect (Chl-a) of the study site in the reservoir by the HAMA-bot operation showed an average 18.5% higher in the treatment area compared to the control area before operation, while the average reduction of 24% in the treatment area after operation. In addition, the Chl-a removal rate, which directly analyzed the influent and effluent of HAMA-bot, showed a very high level with an average of 96.9% (94.7~99.2%). Currently, it is optimized for urban reservoirs and manufactured on a small scale, but it is a useful tool that can be applied on a large scale to large dams and rivers, and it is considered that the field applicability would be improved with the optimized scale.

해조류에는 항산화, 항염증에 효과적인 다양한 생리 활성 화합물이 풍부하게 함유되어 있으며, 장에 유익한 섬유질이 다량 포함되어 있다. 이러한 특징들로 인하여 해조류는 기능성 식품 제조뿐만 아니라, 약리학, 의학적 응용 분야 등 다양한 산업 분야에서 중요한 자원으로 인식되고 있으며, 특히 해조류 발효 기술은 이러한 산업들에 다양한 방법으로 활용될 수 있다. 해조류는 새로운 생리 활성 화합물의 중요한 공급원으로 인정받고 있지만, 육상 식물 바이오매스에 비해 발전이 부족한 상태이다. 해조류를 산업적으로 사용하기 위해 이용되는 해조류 화합물 추출 기술에는 세포벽 처리의 어려움으로 인해 수율이 낮거나 비용 효율성이 떨어지는 등의 문제가 있으나, 최근에는 유산균과 효모종의 미생물을 이용하여 새로운 해조류 발효 제품을 만들어내는 기술이 발전하고 있다. 이러한 해조류 발효 제품은 기능성 식품 및 건강기능식품 시장에서 중요한 역할을 할 수 있으며, 소비자들에게 더 매력적인 제품을 제공할 수 있다. 해조류 발효는 해양 자원의 부가가치를 높이는 중요한 방법 중 하나로, 이를 통해 폴리페놀 함량, 항산화 활성, 생리활성 화합물의 생체 이용률을 증가시키고, 해조류의 감칠맛을 개선하여 소비자들의 만족도를 높일 수 있다. 또한, 해조류 발효는 대량의 양식 바이오매스를 보존할 수 있는 지속 가능한 가공 방법이며, 독성 화학 물질을 생략하여 자연스러운 추출 방법을 제공할 수 있다. 해조류 발효 기술은 아직 많은 연구가 필요하지만, 해조류 산업의 확대와 함께 미래에 매우 중요한 역할을 할 것으로 전망된다.

기존에는 생산되는 키틴과 키토산의 대부분이 게, 새우등 갑각류 껍질에서 유래하였다. 하지만 어업에 의존하 는 기존 갑각류 비해 친환경적이며 품질 유지에 이점을 가지는 곤충으로부터 유래한 키틴이 최근 주목 받기 시작 하며 연구가 활발해지고 있다. 이에 키토산이 남조류의 응집을 통해 녹조 제거 효과를 가지며 기존에 녹조를 억제하기 위해 널리 사용되던 살조제들이 독성을 띠어 환경에 악영향을 미치는 문제를 해결할 수 있다는 연구를 참고하여 매미 탈피각으로부터 추출한 키토산을 녹조 방제에 활용해 보고자 하였다. 매미 탈피각으로부터 키토 산을 추출하고 대표적인 녹조 원인종인 Microcystis aeruginosa 배양 후 추출한 키토산을 처리하여 녹조의 응집 효과를 관찰하였다. 본 연구에서 새로운 키토산 추출 원으로서 매미 탈피각의 가능성을 제시하였으며 이를 녹조 방제에 활용함으로써 버려지는 자원인 매미 탈피각의 활용 방안을 제시하였다.

Marine macroalgae are important in coastal ecosystems and interact with marine microorganisms. In this study, we isolated fungi from seven types of marine macroalgae including Cladophora sp., Gloiopeltis furcate, Gracilariopsis chorda, Hydroclathrus clathratus, Prionitis crispata, Sargassum micracanthum, and Ulva lactuca collected in Korea. Morphological and phylogenetic analyses identified the isolates as four Aspergillus spp. (A. fumigatus, A. sydowii, A. tamarii, and A. terreus), three Penicillium spp. (P. crustosum, P. jejuense, and P. rubens), and Cladosporium tenuissimum. Among them, A. fumigatus TOPU2, A. tamarii SH-Sw5, and A. terreus GJ-Gf2 strains showed the activities of all enzymes examined (amylase, chitinase, lipase, and protease). Based on the enzymatic index (EI) values in solid media, A. terreus GJ-Gf2 and C. tenuissimum UL-Pr1 exhibited the highest amylase and lipase activities, respectively. Chitinolytic activity was only observed in A. terreus GJ-Gf2, A. tamarii SH-Sw5, and A. fumigatus TOP-U2. Penicillium crustosum ULCl2 and C. tenuissimum UL-Pr1 showed the highest protease activities. To the best of our knowledge, this is the first report of lipolytic and proteolytic activities in a marine-derived C. tenuissimum strain. Overall, the fungal strains isolated from the marine macroalgae in this study actively produced industrially important enzymes.

Freshwater and brackish blue-green algae were collected at 43 freshwater and brackish sites (including lakes, ponds, swamps, streams, and rivers and estuaries) throughout South Korea from March 2017 to October 2018, and were identified using light microscopy. A total 223 taxa in freshwater and 230 taxa in brackish waters in 2017 and 274 taxa in fresh and brackish waters in 2018 were identified and among them, 20 taxa were unreported taxa of blue-green algae in Korea; The new recorded taxa were Aphanocapsa marina, Calothrix fusca f. durabilis, Calothrix littoralis, Calothrix parva, Chamaesiphon minimus, Chroococcidiopsis cubana, Chroococcidiopsis fissurarum, Coelosphaerium aerugineum, Dolichospermum mendotae, Eucapsis alpine, Gomphosphaeria cordiformis, Gomphosphaeria natans, Merismopedia danubiana, Lynbya aestuarii var. gaditana, Tolypothrix tenuis, Pseudocapsa maritima, Pseudocapsa sphaerica, Pseudophormidium tenue, Trichodesmus sp. and Woronichinia elorantae.

국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.

The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO4) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO4. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO4 significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO4 is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.

Agar, a heterogeneous polymer of galactose, is the main component of the cell wall of marine red algae. It is well established as a safe, non-digestible carbohydrate in oriental countries. Neoagarooligosaccharides (NAOs) prepared by hydrolyzing agar by microbial β-agarase have been reported to show safety. However, their immunological effects have not been reported yet. Thus, the objective of this study was to investigate immune enhancing effects of neoagarooligosaccharides (NAOs) from marine red algae Gelidium elegans in mice by performing ex vivo experiments. Six-week-old mice were fed ad libitum. NAOs were orally administrated at three different concentrations (100, 500, and 2,500 mg/kg B.W./day) twice a week for four weeks. The group fed with NAOs at 2,500 mg/kg showed the highest proliferation of splenocytes and production levels of cytokines (IL-1β, IL-6, TNF-α) in the ex vivo experiment. In conclusion, NAOs can enhance immune function, increase proliferation of splenocytes, and increase cytokine production by activating macrophages in mice.

Prediction of the behavior of heavy metals over time is important to evaluate the heavy metal toxicity in algae species. Various modeling studies have been well established, but there is a need for an improved model for predicting the chronic effects of metals on algae species to combine the metal kinetics and biological response of algal cells. In this study, a kinetic dynamics model was developed to predict the copper behavior (5 μg L-1, 10 μg L-1, and 15 μg L-1) for two freshwater algae (Pseudokirchneriella subcapitata and Chlorella vulgaris) in the chronic exposure experiments (8 d and 21 d). In the experimental observations, the rapid change in copper mass between the solutions, extracellular and intracellular sites occurred within initial exposure periods, and then it was slower although the algal density changed with time. Our model showed a good agreement with the measured copper mass in each part for all tested conditions with an elapsed time (R 2 for P. subcapitata: 0.928, R 2 for C. vulgaris: 0.943). This study provides a novel kinetic dynamics model that is compromised between practical simplicity and realistic complexity, and it can be used to investigate the chronic effects of heavy metals on the algal population.

통영 LNG 기지에서 방류되는 냉배수가 진해만에 미치는 영향을 알아보고, 냉배수의 활용 방안 모색을 위해 총 4개의 냉배수 방류량에 대한 진해만의 환경변화를 1년간(2018년) 모의하였다. 실제 냉배수 방류량인 Case1(10 m3 sec-1)의 모의 결과, 모든 분기에서 냉배 수에 의한 진해만의 환경변화는 매우 미미하게 나타났다. 모의 방류량인 Case2(100 m3 sec-1)의 경우 방류구 반경 5 km 범위에서 1 ~ 3℃의 수온 감소를 보였으며, Case3(1000 m3 sec-1)에서는 방류구 반경 8 km 범위에서 최대 4 ~ 5℃의 수온이 감소하였고 진해만 전 해역에 걸쳐 냉 배수가 확산하는 결과를 보였다. 플랑크톤의 성장 속도는 최대 15% 감소하였으며(11월), 대형조류의 성장 속도는 행암만 부근에서 최대 6 % 증가하는 결과를 보였다. 상기 결과로부터 통영 LNG 기지에서 방류되는 냉배수에 의한 진해만의 환경변화는 미미한 것을 확인하였 다. 또한 Case3 결과로부터 국소지역의 ‘적조 방재’, ‘해조류 성장’을 목적으로 냉배수의 활용이 가능할 것으로 기대된다.

본 연구에서는 2020년 6월에서 9월까지 4개월 동안 우리나라 하천 중 금강 백제보에 주로 서식하는 말조개, 펄조개와 대칭이를 채집하여 서식처 특성을 살펴보았고, 이들의 여과율을 실내 실험을 통하여 측정하여 검량선을 산출하였다. 백제보에서 채집된 말조개, 펄조개, 대칭이는 24시간 동안 평균 154.84 μg L-1의 Chl-a를 제거하였으며, 이는 실내 수조 (2 L) 내의 식물플랑크톤 C. vulgaris (초기 Chl-a=168.34 μg L-1)를 약 24시간 만에 제거할 수 있는 것으로 나타났다. 따라서, 본 연구에서 사용한 말조개, 펄조개, 대칭이가 연평균 4 만 마리가 서식할 경우 (Lee et al., 2020), 6월 한달 동안 예상되는 Chl-a의 저감 효과는 10.55%으로 예측되고 7월의 경우 34.88%, 8월의 경우 20.14%, 9월의 경우 46.21%로 평균 27.94%의 저감 효과를 예상할 수 있다. 이러한 결과는 간접적으로 이매패류가 서식지에서 효과적으로 Chl-a를 제거 할 수 있을 가능성을 제시한다. 실제로 이매패류를 통하여 수생태계의 조류 제어능력을 평가하기 위해서는 이매패류뿐만 아니라 식물플랑크톤, 수생식물, 저서생물, 퇴적물, 유속 등의 작용들을 종합적으로 고려해야 하지만 본 연구에서는 이매패류의 여과율과 이에 따른 Chl-a에 저감율에 기반하여 수생 태계 조류 제어능력을 산정하였다. 본 연구 결과들은 차후 다양한 요인과 관점에서의 통합된 연구에 기초적인 정보를 제공할 것으로 사료된다.

The genus Petroderma never been reported from the coast of Korea. In this study, our collection from Chaeseokang is matched with P. maculiforme morphologically. Petroderma maculiforme is characterized by having small irregular light to dark brown crusts, a basal layer of irregularly shaped cells giving rise to erect parallel filaments which easily separate with pressure, single chromatophore per cell, small spherical to cylindrical unilocular sporangia in a terminal position, and plurilocular sporangia narrower than erect filaments or wider and shorter than erect filaments in a terminal position. In addition, Hineksia sordida was also collected from Korea. It is mostly epiphytic and characterized by uniseriate filamentous thalli forming loose tangled masses, sparse and spiral branching, some long lateral branches, rhizoids occurring throughout the plant, plurilocular and unilocular sporangia scattered on separate plants. Our molecular analyses based on the rbcL gene reveal that our samples of P. maculiforme and H. sordida are nested within the clades of Petroderma and Hincksia, respectively. Therefore P. maculiforme and H. sordida are reported as new records from Korea based on morphological and molecular analyses.

Papenfussiella densa was described as Papenfussiella kuromo f. densa from Japan by Inagaki in 1958. P. densa has been recognized as an endemic and independent species based on the molecular analyses of type material without detailed morphological observations. In this study, Papenfussiella densa is reported as a new record from Dok-do, South Korea, based on morphological and molecular analyses. Papenfussiella densa is mainly characterized as having narrow, branched, slimy, and tomentose thalli with branchlets, partially hollow in the medulla of the middle part. The molecular analyses of the chloroplast rbc L-rbc S DNA sequence of the Papenfussiella densa sample from Korea revealed that it matched that of P. densa from Japan and was nested in the clade of Papenfussiella. There was only a 0.02% gene sequence divergence between the Korean and Japanese samples. We report P. densa as a new record from Korea and add this species to the list of Korean macroalgal flora.