Distribution of Epilithic Diatoms in Estuaries of the Korean Peninsula in Relation to Environmental Variables

Abstract

This study explores the relationships between environmental factors and the distribution of epilithic diatoms in 161 estuaries of three coastal areas on the Korean peninsula. We investigated epilithic diatoms, water quality, and land use in the vicinities of the estuaries during the months of May 2012, 2013 and 2014, because Korea is relatively free from the influences of rainfall at that time of year. We recorded 327 diatom taxa from the study sites, and the assemblage was dominated by members of the Naviculaceae. Bacillariaceae accounted for the largest proportion of diatoms, and Nitzschia inconspicua (18%) and N. frustulum (9.6%) were the most dominant species. A cluster analysis based on epilithic diatom abundance suggested that the epilithic diatom communities of Korean estuaries can be classified into four large groups (G) according to geography, as follows: Ia-the East Sea watershed, Ib-the eastern watershed of the South Sea, IIa-the West Sea watershed, and IIb-the western watershed of the South Sea. The former two groups, Ia and Ib, showed higher proportions of forest land cover and use, higher species occurrence, lower salinity, lower turbidity, and lower concentrations of nutrients than the latter two groups, while the latter groups, IIa and IIb, had higher proportions of agricultural land cover and use, higher electrical conductivity, higher turbidity, higher concentrations of nutrients, and lower species occurrence. The environmental factors underlying the distribution of epilithic diatoms, representative of each region, are as follows: dissolved oxygen and forest land cover and use for Reimeria sinuate and Rhoicosphenia abbreviate of the East Sea (ES), salinity and turbidity for Tabularia fasciculate of the West Sea (WS), and biochemical oxygen demand (BOD) and nutrients for Cyclotella meneghiniana of the WS. On the other hand, the most influential environmental factors affecting the occurrence of indicator species showing the highest indicator values (>60%) of each group were electrical conductivity for Navicula saprophila and Reimeria sinuate of Ia, and turbidity for Encyonema minutum of IIa. Collectively, the distribution of epilithic diatom communities inhabiting Korean estuaries are determined by geographical factors and water quality, which are in turn influenced by land cover and use, and which differ from east to west.

Benthic Diatom Communities in Korean Estuaries: Species Appearances in Relation to Environmental Variables

“…During the study period, 566 taxa of epilithic diatoms were identified in 512 sites. These results determined a higher number of taxa than the 327 taxa found in 161 sites between 2012 and 2014 in a previous study [31], which appears to be the result of the present study having more survey sites than previous studies. With respect to dominant species, the Nitzschia genus appeared in over 38% of estuaries in the Korean Peninsula.…”

“…In Korea, aquatic ecosystem health assessments have been conducted every year since 2008, using epilithic diatoms for most of the rivers throughout the country [26]. However, there is very little information with respect to employing epilithic diatoms as indicator organisms for estuaries, as studies in Europe and Korea are very limited [27,28,29,30,31]. The majority of studies related to estuaries have concentrated on red-tide or eutrophication phenomena, which are caused by marine aquaculture or nutrients introduced into rivers, while other studies have focused mainly on ecological research of biological communities, such as phytoplankton, vegetation structure, fish, and benthic animals, including water quality [32,33,34,35].…”

Plankton and benthos similarity indices as indicators of the impact of mangrove plantation on the environmental quality of silvofishery ponds

“…and Navicula sp. These plankton species are considered to be indicators of good levels of dissolved oxygen concentration (Kim et al 2015). These types of dominant plankton species suggest that the water in the ponds is enriched with nutrients and has good water circulation.…”

Assessment of River-Sea Interaction in the Danube Nearshore Area (Ukraine) by Bioindicators and Statistical Mapping

“…Colleagues from Ukraine, working within the framework of the development of a national marine strategy, are actively introducing a morphological and functional approach to assess the state of the environment using indices of the specific surface area of macrophytes and microalgae [24][25][26]. Integrated indices and comparative statistics, using various structural indicators of marine and estuarine ecosystems, is widespread [27,28].…”

“…However, applying these approaches to assessing the state of marine ecosystems has not yet received widespread use due to the limited number of indicator species [20,21,32]. The combined approach of studying the species composition of algae and statistics in the coastal area has good examples of its application [28]. We believe it rational to apply this complex of methods for the Danube nearshore area-a dynamically changing ecosystem, using phytoplankton's structural indicators and the content of nutrients.…”