• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.452-460
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• 2017

Rice fields are important stopover sites for the conservation of shorebirds during long-distance migration. These fields serve as food sources providing energy for the next leg of the journey. Shorebirds are able to change their preferred food source at stopover sites. However, the type and distribution of food resources remain unknown for the shorebirds in the Republic of Korea. Therefore, we studied the type and distribution pattern of food resource (macroinvertebrates, remaining rice, and other seeds) for shorebirds in the rice fields. We have identified potential and actual food sources for shorebirds in the rice fields. The potential food sources were collected by using a core-sampling method and the actual food source was ascertained by observational analysis. As a result, a total 19 species of benthic macroinvertebrates in 15 families were recorded as potential food sources. A total of 9 families in 9 orders of benthic macroinvertebrates known to be actual food sources were also recorded during the study period, including loaches, and a tuber of sea club rush. Also, the distribution of the food source depended on soil conditions generated by cultivation such as plowing, harrowing, and the use of pesticides. In the present study, we identified the type and distribution of food sources for shorebirds. This information can be used as essential primary baseline data for conservation of shorebirds using the rice fields of the Republic of Korea.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.368-375
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• 2022

Gut contents analysis is essential to predict the impact of organisms on food source changes due to variations of the habitat environment. Previous studies of gut content analysis have been conducted using traditional methods, such as visual observation. However, these studies are limited in analyzing food sources because of the digestive process in gut organ. DNA metabarcoding analysis is a useful method to analyze food sources by supplementing these limitations. We sampled marine fish of Pennahia argentata, Larimichthys polyactis, Crangon affinis, Loligo beka and Sepia officinalis from Gwangyang Bay and Yeosu fisheries market for analyzing gut contents by applying DNA metabarcoding analysis. 18S rRNA v9 primer was used for analyzing food source by DNA metabarcoding. Network and two-way clustering analyses characterized the relationship between organisms and food sources. As a result of comparing metabarcoding of gut contents for P. argentata between sampled from Gwangyang Bay and the fisheries market, fish and Copepoda were analyzed as common food sources. In addition, Decapoda and Copepoda were analyzed as common food sources for L. polyactis and C. affinis, respectively. Copepoda was analyzed as the primary food source for L. beka and S. officinalis. These study results demonstrated that gut contents analysis using DNA metabarcoding reflects diverse and detailed information of biological food sources in the aquatic environment. In addition, it will be possible to provide biological information in the gut to identify key food sources by applying it to the research on the food web in the ecosystem.

• Korean Journal of Ecology and Environment
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• v.54 no.2
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• pp.130-141
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• 2021

By reviewing previous literature, we analyzed the food sources of 20 out of 29 endangered fish species from freshwater ecosystems in South Korea. A total of 19 studies reported that food sources of 20 endangered fish species included 20 phyla, 31 classes, 58 orders, 116 families, and 154 genera. Arthropod, insecta, diptera, and chironomidae were the most fed animal food sources according to different resolution of taxa index on phylum, class, order and family. Similarity, bacillariophyta, bacillariophyceae, naviculales, and cymbellaceae were the most fed abundant plant sources. A larger number of fish species were reliant on animal food sources than plant food sources. 18 of the endangered fish preyed on arthropods, whereas only 6 species consumed bacillariophyta. To characterize the feeding groups of the 20 fish species, a hierarchical clustering analysis and non-metric multidimensional scaling analysis were conducted. The fish species were divided into two groups: 1) insectivores and 2) planktivores. A network analysis, which associated the link between endangered fishes and food sources, also revealed the same two groups. The highest hub score of food sources was for macroinvertebrates, including diptera (0.47), ephemeroptera (0.42), and trichoptera (0.38), based on the network analysis. Niche breadth was used to calculate the diversity of the food sources. Phoxinus phoxinus (0.57) showed thehighest food source diversity among the fish species, whereas Iksookimia pacifica (0.01) showed the lowest. This study will be utilized for the conservation and restoration of the endangered fish species.

• Korean Journal of Ecology and Environment
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• v.53 no.4
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• pp.311-323
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• 2020

We analyzed food sources of 45 fish species in 28 genera of 12 families based on literature data in freshwater ecosystems of South Korea. The food sources of 45 fish species included in a total of 26 phyla, 42 classes, 94 orders, 189 families and 294 genera. Among them, animal food sources were 16 phyla, 24 classes, 54 orders, 126 families and 212 genera, whereas plant food sources were relatively small with 10 phyla, 18 classes, 42 orders, 63 families and 82 genera. The animal food sources were classified into Arthropod, Insecta, Diptera and Chironomidae according to taxa. Meanwhile, Bacillariophyta, Bacillariophyceae, Cymbellales and Cymbellaceae were the most abundant among the plant sources. Self-Organized Map (SOM) and network analysis were conducted the food sources were classified into taxonomic groups and the feeding types of fish : 45 fish species were divided into five groups, characterizing 1) fishvores, 2) invertebratevores, planktivores including 3) zooplankton and 4) phytoplankton, and 5) omnivores. The network analysis presented link association between fishes and food sources. Macroinvertebrate including diptera and ephemeroptera were revealed as hub food sources based on network analysis. This literature study would expect that the application model with the food source of fish could be utilized for the evaluation of the food network or chain in freshwater ecosystems.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.604-614
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• 2022

This study analyzed habitat status of barn swallows within 800 m and changes in potential food resource occurrence for 63 nests (Seocheon 23, Sejong 40) where barn swallows breeding was confirmed in Seocheon and Sejong in 2019 and 2020. As a result of checking habitat compositions of barn swallows in the study area, Sejong showed more varieties of habitat types than Seocheon, showing a larger number of dominant groups. Such large number of dominant groups was found to be an advantageous habitat factor for producing flying insects as potential food resources for barn swallows. As for the production of potential food resources, Seocheon had the highest production in dwelling and stream and Sejong had the highest production in the stream. The production of potential food resources differed in production season by habitat type. This study analyzed compositions of the habitat around the breeding site of swallows. It provides basic data necessary for protecting barn swallow habitats by comparing the production timing and production volume of potential food resources occurring in the habitat.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.80-88
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• 2016

In order to reconstruct a benthic foodweb structure and assess the role of benthic microalgaes as a diet source for benthos, we analyzed the carbon and nitrogen stable isotopes of diverse benthos (bivalves, crustaceans, gastropods and fishes) and potential diets (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass, and macroalgaes) in the intertidal mudflat surrounding Yeongheung Island. The ${\delta}^{13}C$ values of the diets indicated wide ranges (- 26.5‰ to - 8.4‰) while benthos showed a small range of ${\delta}^{13}C$ values (-12.1‰ to - 17.8‰), although they were in the same range. Except for green algaes among the macroalgaes as well as sedimentary organic matter, ${\delta}^{15}N$ values of the diet candidates ($5.7{\pm}1.0$‰) were lighter in comparison to those of the benthos ($11.8{\pm}1.9$‰). Based on the ${\delta}^{13}C$ and ${\delta}^{15}N$ data, the benthos were classified into 3 groups, indicating a different diet and trophic position. But benthic microalgae is the most important diet source for all three benthos groups based on their stable isotope ratios, suggesting benthic microalgae should be a main diet to the intertidal ecosystem. Hence this study highlights that the biomass of benthic microalgae as biological resource should be evaluated for the management of the intertidal ecosystem of Yeongheung Island.

• Korean Journal of Ecology and Environment
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• v.54 no.3
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• pp.257-264
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• 2021

In this study, we analyzed the food components in the release product that sampled Sinonovacula constricta from the foreshore littoral at Byeongnyang-myeon, Suncheon Bay. We used microscopy and next-generation sequencing (NGS) to evaluate the applicability of morphological and molecular methods to analyze release products. The higher species diversity observed in the NGS method is due to the different levels of species identification, as microscopy displays morphological and anatomical levels of plankton species identification in S. constrita. Moreover, NGS can identify the level of species in the organic matter by using the 18s_V9 primer.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.97-102
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• 2012

The purpose of this study is to clarify the origin and the variation of essential fatty acid (FA) and food sources of Stenopsyche marmorata at downstream region of Dam. As a result, the water particulate organic matter (POM) is mainly derived from diatom, green algae and bacteria. Moreover, the main food sources of S. marmorata mainly used diatom, green algae and bacteria. ${\omega}3$ essential FA of S. marmorata was higher than ${\omega}6$, and showed about 7 for essential FA ratio.

• Korean Journal of Environment and Ecology
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• v.32 no.1
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• pp.55-65
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• 2018

This study was conducted to clarify diet items and predatory behavior of American bullfrog (Lithobates catesbeianus) according to the sex, maturity and season from April to September 2014 at Gahang wetland of Changnyeong-gun, Gyeongsangnamdo province, Korea. We examined the stomach contents of L. catesbeianus using a gastrectomy technique and identified the contents to a genus or species. The examination showed that large and heavy individual of L. catesbeianus fed on larger amounts of food. However, there were no statistically significant differences in predation amount according to the sex and maturity of L. catesbeianus. The main diet item of during the study period was mostly Insecta (average population rate of 65.5%), followed by Crustacea (13.5%) and Gastropoda (7.9%). The most preferred diet item of L. catesbeianus was Muljarus japonicus. Surprisingly, L. catesbeianus also foraged Parus major, Apodemus agrarius, and Crocidura lasiura. Ths findings showed that L. catesbeianus directly disturbed the wetland ecosystem. We expect the results will be the important reference data for checking the impact of L. catesbeianus, which is designated as invasive species by the Ministry of Environment, on wetland ecosystem.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.368-373
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• 2015

Faecal analysis was carried out to identify the diet composition of Eptesicus serotinus after collecting the faeces from 25 female bats. Five bats were captured at a bridge where a colony of E. serotinous was found in Andong city, Gyeongbuk, every month from May to September 2014. A total of 100 faeces were collected and the parts of insects obtained from the faeces were examined using a high-resolution microscope (50 ${\times}$ binocular microscope) and then the orders of the insects were identified by the characteristics of the parts of the insect (mouthpart, leg, wing, antenna, elytra, etc.). According to the results of the faecal analysis, 4 orders: Coleoptera, Hymenoptera, Diptera and Hemiptera were used as food resource of E. serotinus. Coleoptera was found in May, July, August, and September. Interestingly, only Coleoptera were found in May and July. Hemiptera, Diptera, and Hymenoptera were found to be used as food resources in September, June, and August.