• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.855-861
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• 2011

Short-term effects of current velocity and turbid water on the benthic diatom community and water quality were examined in artificial channel ($20{\times}200{\times}10cm$) with two different experiments. The first and second experiments were consisted of different current velocities such as 1 L/min., and 1, 3, and 6 L/min., respectively. The concentration of turbid water is prepared with loess and fixed at 10 and 20 times of the turbidity of control inflow (10 NTU, LTW), respectively. At experiment 1 (EXP-1), introduction of turbid water increased dissolved oxygen, electric conductivity, pH and turbidity, but there were no differences between low- (100 NTU, MTW) and high-turbid water (200 NTU, HTW). However, experiment 2 (EXP-2) did not change any environmental parameters except dissolved total and inorganic nitrogen like EXP-1. MTW in EXP-1 strongly stimulated the growth of benthic diatom, while both MTW (150 NTU) and HTW (300 NTU) in EXP-2 did not increase or decrease the diatom abundance. Over the study, the dominant species was four, Aulacoseira ambigua, Cyclotella stelligera, Aulacoseira granulata and Achnanthes minutissima. In EXP-1, two highest species in abundance, A. ambigua and A. granulata were highly grown in MTW, while Achnanthes minutissima high in HTW adversely. These results indicate that the introduction of turbid water can play an important role in the shift of water quality and benthic diatom community in stream ecosystem, especially inflow of soil water in low current velocity.

• ALGAE
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• v.35 no.4
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• pp.361-373
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• 2020

The community dynamics of benthic diatoms in the hypersaline environment are investigated to advance our understanding how salinity impacts marine life. Diatoms were sampled in the two salterns encompassing salt Ponds, ditches, and seawater reservoirs (n = 11), along the salinity gradient (max = 324 psu), and nearby tidal flats (n = 2). The floral assemblages and distributions across sites and stations showed great variations, with a total of 169 identified taxa. First, not surprisingly, higher diversity of benthic diatoms was found at natural tidal flats than salterns. The saltern diatoms generally showed salinity dependent distributions with distinct spatial changes in species composition and dominant taxa. Biota-environment and principal component analysis confirmed that salinity, mud content, and total nitrogen were key factors influencing the overall benthic community structure. Some dominant species, e.g., Nitzschia scalpelliformis and Achnanthes sp. 1, showed salinity tolerance / preference. The number of diatom species at salinity of >100 psu reduced over half and no diatoms were found at maximum salinity of 324 psu. The highest salinity for the observed live diatoms was 205 psu, however, a simple regression indicated a theoretical salinity threshold of ~300 psu on the survival. Finally, the indicator species were identified along the salinity gradient in salterns as well as natural tidal flats. Overall, high species numbers, varying taxa, and euryhaline distributions of saltern diatoms collectively reflected a dynamic saltern ecosystem. The present study would provide backgrounds for biodiversity monitoring of ecologically important microalgal producers in some unique hypersaline environment, and elsewhere.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.879-885
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• 2009

The present study was carried out to develop biological criteria for water quality assessment using benthic diatoms. Selecting of the indicator diatoms, three parameters were considered: broad distribution (180 taxa occurred over 3% at upper level), species abundance (158 taxa occurred over $1.5{\times}10^5cells/cm^2$), and sensitivity (184 taxa occurred more than once as 1st and 2nd dominant species). Overall, total 208 taxa were selected, including 38 varieties, 170 species, 34 genera, 9 families, 3 orders, and 1 phylum. The most dominant taxonomic group (family) was Naviculaceae (52%), followed by Diatomaceae (15%), Nitzschiaceae (12%) and Achnantaceae (11%). COD and TP were proposed as new water quality standards (draft) to improve the existing BOD standard and to manage and control efficiently non-biodegradable organic pollutants. With this regard, we used TP standard (draft) in developing biological water quality criteria for diatoms. TP standards (draft) proposed as Ia = 0.02 mg/L or less, Ib = 0.05 mg/L or less, II = 0.1 mg/L or less, III = 0.2 mg/L or less, IV = 0.4 mg/L or less, V = 0.6 mg/L or less and VI = above 0.6 mg/L. Biological assessment system (4 class system) was developed and proposed for diatom using modified Tropic Diatom Index (TDI). Biological assessment of TDI appear B grade (Good).

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.129-138
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• 2012

We investigated an ecological impact of drought simulated by discharge depletion on the water quality and benthic diatom community in the indoor experimental channel. As artificial substrates slide-glass was installed in acrylic channel for 16 days. Channels were supplied continuously with eutrophic lake water with a discharge rate of 6 L $min^{-1}$ in duplication during the colonized period. And then during the discharge depletion period, three discharge rates were provided: NDF (No depletion of flow rate (Control): 6 L $min^{-1}$), LDF (Low depletion of flow rate: 3 L $min^{-1}$) and HDF (High depletion of flow rate: 1 L $min^{-1}$). Environmental factors in the water, such as suspended solid, Chl-$a$ and nutrients concentration, were measured with periphytic algae including AFDM (ash free dry matter), Chl-$a$ concentration and cell density at 1-day intervals. Light intensity increased significantly with discharge depletion (F=229.5, p= 0.000). $NH_4$-N concentration was highest at HDF. Suspended solid in outflowing water decreased at HDF (88%), LDF (97%) and NDF (99%), compared to inflowing water (100 %). Chl-$a$ in substrates increased more than two times at LDF and HDF than NDF (F= 8.399, p=0.001). Also AFDM and benthic diatom density increased significantly at LDF and HDF than NDF (F=9.390, p=0.001; F=6.088, p=0.007). In all experimental groups, $Aulacoseira$ $ambigua$, $Achnanthes$ $minutissima$ and $Aulacoseira$ $granulata$ were dominant species accounting for greater than 10% of benthic diatom density. The most dominant species, $A.$ $ambigua$ was highest at LDF, followed by HDF and NDF (F=8.551, p=0.001). In conclusion, the effect of drought simulated by discharge depletion in an artificial stream ecosystem caused significant changes on water quality and benthic diatom biomass. This result provides a useful data to understand the effect of draught on stream ecosystem in situ.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.110-122
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• 2012

This study examined the benthic diatom community distribution, land cover/use and water quality in relation to stream shape complexity (SSC) in the Seom River watershed. SSC showed a significant relation to the riparian land cover/use pattern and also water quality variables of the studied streams. Streams with high stream shape complexity (HSC) appeared to have a high proportion of forest and farmland, while streams having a low stream shape complexity (LSC) appeared to have high proportion of city. Streams with lower SSC showed higher nutrients concentration in the stream waters. Benthic diatom species composition and dominant species appeared to be similar regardless of SSC differences among the studied streams, while the variation of diatom density was manifested with SSC. The relative abundance of dominant benthic diatoms varied with SSC. Saprophilic diatoms were dominant in the streams of LSC, while saproxenic diatoms were dominant in the streams of HSC. During the evaluation of biological water quality using the benthic diatom indices, Trophic Diatom Index (TDI) and Diatom Assemblage Index to organic water pollution (DAIpo), the streams of LSC generally showed poorer water quality than those of MSC (Middle stream shape complexity) and HSC. In particular, BOD, TP, and $PO_4$-P showed significant relationships with DAIpo. In conclusion, shape complexity of streams in the Seom River watershed showed a close relation with benthic diatom distribution. This relation seemed to primarily be resulted from the effect of proximate factors, such as water quality, which might be affected by the land use types determining the degree of SSC.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.249-260
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• 1998

To understand the attachment of micro algae and their subsequent growths on artificial surfaces immersed in seawater, the relationship between attachment of diatoms on the immersed artificial substrates and species pool in the surrounding water was investigated. We used acryl slides for the study of diatom attachment and examined the surrounding water samples collected in Incheon Harbour from July 1995 to February 1997. Variations of species composition and abundances by exposure time in seawater were investigated during the early phase of biofilm formation on various substrates, e.g. glass, acryl, titanium, copper and antifouling paint-treated slides. Immigration rates of diatoms to acryl slides during spring and winter were significantly correlated with the abundance of benthic diatoms in surrounding water ($r^2$=0.78, p<0.01, n=42), suggesting that immigration rates were affected by variations of benthic diatom abundances in surrounding water. Immigration coefficient of monoraphid diatoms was 5 times higher than that of biraphid diatoms, but relative abundance of monoraphid diatoms was 3 times lower than that of biraphid diatoms on acryl slides in spring. In winter, immigration coefficient and relative abundance of centric diatoms were higher compared to other raphe forms. These results suggest that the attachment of diatoms seems to be caused by the abundance and immigration coefficients of benthic diatoms in surrounding water. Pennate diatoms predominantly attached to all artificial surfaces throughout all experimental periods. Interestingly, centric diatoms predominantly attached to all artificial surfaces in winter. Hantzschia virgata, Licmophora abbreviata and Melosira nummuloides appeared dominantly on antifouling paint-treated slides, probably being tolerant of the antifouling paint. During incubations, the abundance of attached diatoms increased exponentially on glass, titanium and acryl slides with exposure time. The maximum abundance was highest on glass slide, followed by acryl, titanium, copper and antifouling paint-treated slides. The growth rates of attached diatom community on all artificial surfaces were higher at temperature of $24-25^{\circ}C$ than that of $2-3^{\circ}C$. The growth rate of attached diatoms on glass slide was generally higher compared to other slides during the study period. Dominant morphotypes of observed species with exposure time in seawater were prostrate form Amphora coffeaeformis, fan shape Synedra tabulata, stalk type Licmophora paradoxa and chain type M. nummuloides. A micro-succession in the attached microalgal community was observed. The composition of dominant species seems to be the result of species-specific response to gradually limited space with development of microalgal film.

• 한국해양학회지
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• v.22 no.4
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• pp.257-270
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• 1987

Fouling communities developing in Jinhae Harbor and Masan Bay were studied by slide and panel immersion test during the period from Dec., 1982 to Nov., 1983. The total viable count of bacteria was estimated more than 1.7${\times}$ 10$\^$4/CFU/$\textrm{cm}^2$ after 15 days of immersion and 46 taxa of benthic diatoms were classified in micro-community. Progressional change of fouling communities was clearly shown and dominant diatom species are Licmophora flavellata, Navicula grevillei, and Nitzschia closterium Major macrofouling organisms are Mytilus edulis, Balanus amphitrite amphitrite, Hydroides ezoensis, and Celleporina sp. Wet weight production of macrofouling organisms exceeds 500g/100cm$\^$2/ after 5months of immersion. Regional defferences in community development are clearly shown in two study areas, and mainly due to the disparities of physicochemical stability and nutritional status of ambient water. Seasonality of larvae and the growth rate are the important factors in fouling community development. Overall process of community development is as follow : bacteria and diatoms-multicellular algae-barnacle, mussels and polychaete-sponge, anemone and ascidian.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.60-75
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• 2022

The Bayesian algorithm model is a model algorithm that calculates probabilities based on input data and is mainly used for complex disasters, water quality management, the ecological structure between living things or living-non-living factors. In this study, we analyzed the main factors affected Korean Estuary Trophic Diatom Index (KETDI) change based on the Bayesian network analysis using the diatom community and physicochemical factors in the domestic estuarine aquatic ecosystem. For Bayesian analysis, estuarine diatom habitat data and estuarine aquatic diatom health (2008~2019) data were used. Data were classified into habitat, physical, chemical, and biological factors. Each data was input to the Bayesian network model (GeNIE model) and performed estuary aquatic network analysis along with the nationwide and each coast. From 2008 to 2019, a total of 625 taxa of diatoms were identified, consisting of 2 orders, 5 suborders, 18 families, 141 genera, 595 species, 29 varieties, and 1 species. Nitzschia inconspicua had the highest cumulative cell density, followed by Nitzschia palea, Pseudostaurosira elliptica and Achnanthidium minutissimum. As a result of analyzing the ecological network of diatom health assessment in the estuary ecosystem using the Bayesian network model, the biological factor was the most sensitive factor influencing the health assessment score was. In contrast, the habitat and physicochemical factors had relatively low sensitivity. The most sensitive taxa of diatoms to the assessment of estuarine aquatic health were Nitzschia inconspicua, N. fonticola, Achnanthes convergens, and Pseudostaurosira elliptica. In addition, the ratio of industrial area and cattle shed near the habitat was sensitively linked to the health assessment. The major taxa sensitive to diatom health evaluation differed according to coast. Bayesian network analysis was useful to identify major variables including diatom taxa affecting aquatic health even in complex ecological structures such as estuary ecosystems. In addition, it is possible to identify the restoration target accurately when restoring the consequently damaged estuary aquatic ecosystem.

• 한국해양학회지
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• v.21 no.3
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• pp.156-170
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• 1986

The phytoplankton ecology of estuarine waters was investigated in the Kyeonggi Bay from May 1981 to September 1982 on monthly basis. In this study area, a total of 228 phytoplankton species was identified. Among these taxa, the most dominant species are diatoms in this area. Tychopelagic plankton occupies 40.4% of total species. The percentage of tychopelagic plankton density ranged from 10.2% in September to 92.7% in March of monthly standing crops. From late autumn to early spring, the percentage values are more than 72%. They play an important role from late autumn to early spring in this estuarine plandton community. These tychopelagic planktons are induced from benthic diatoms. Because the bottom shear stresses generated by the tides and winds are stronger than the adhesive and tractive force of benthic diatoms, most of benthic diatoms must be resuspended into tychopelagic suspensions during autumn and winter. Paralia sulcata is the most important tychopelagic plankton as an indicator species of water mixing in the eastern coastal area of Yellow Sea. This species seems to have even broader tolerance to the environmental stress than Skeletonema costalum, and tends to fill the gaps in winter, when the phytoplandton is relatively unsuccessful. Skeletonema costatum and Chaetoceros debilis are dominant in other seasons. Typical blooms of phytoplankton occur in spring and early autumn, The first bloom is started by Skeletonema costatum in early May, second peak is formed by various diatom population in September.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.84-98
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• 2022

Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.