• ALGAE
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• v.31 no.1
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• pp.17-31
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• 2016

To explore the feeding ecology of the newly described heterotrophic dinoflagellate Aduncodinium glandula in the family Pfiesteriaceae, its feeding behavior and prey species were investigated. Additionally, the growth and ingestion rates of A. glandula on the mixotrophic dinoflagellates Heterocapsa triquetra and Akashiwo sanguinea, its optimal and suboptimal prey, respectively were measured. A. glandula fed on prey through a peduncle after anchoring to the prey using a tow filament. A. glandula ate all algal prey and perch blood cells tested and had the most diverse prey species in the family Pfiesteriaceae. Unlike for other pfiesteriacean species, H. triquetra and A. sanguinea support the positive growth of A. glandula. However, the cryptophytes Rhodomonas salina and Teleaulax sp. and the phototrophic dinoflagellate Amphidinium carterae did not support the positive growth of A. glandula. Thus, A. glandula may have a unique kind of prey and its optimal prey differs from that of the other pfiesteriacean dinoflagellates. With increasing mean prey concentration, the growth rates of A. glandula on H. triquetra and A. sanguinea increased rapidly and then slowed or became saturated. The maximum growth rates when feeding on H. triquetra and A. sanguinea were 1.004 and 0.567 d⁻¹, respectively. Further, the maximum ingestion rates of A. glandula on H. triquetra and A. sanguinea were 0.75 and 1.38 ng C predator⁻¹ d⁻¹, respectively. There is no other pfiesteriacean species having H. triquetra and A. sanguinea as optimal and suboptimal prey. Thus, A. glandula may be abundant during blooms dominated by these species not preferred by the other pfiesteriacean dinoflagellates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.165-179
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• 2006

Food habits of the gavelin goby Acanthogobius hasta and the fine spot goby Chaeturichtys stigmatias populations were investigated in the Jangbong tidal flat near Incheon, Korea. Samples were taken monthly from November 1999 to January 2001. The gut contents of 248 gavelin gobies and 139 fine spot gobies were analyzed. The diet of the gavelin goby was dominated by the gammaridean amphipod Chitinomandibulum emargicoxa, the crabs Macrophthalmus japonicus and Ilyoplax pingi, the shrimp Exopalaemon carinicauda, the bivalve Raetellops pulchella and the macro-algae Porphyra tenera. On the other hand, the fine spot goby mainly feed on the shrimps Crangon affinis, Latreutes mucronatus, E. carinicauda and Alpheus japonicus, the gammaridean amphipods C. emargicoxa and Synchelidium miraculum, and the bivalve R. pulchella. A comparison between frequencies of occurrence and abundance of food items in the gut showed that crustaceans (gammaridean amphipods, crabs and shrimps) and bivalves were important foods for the two gobies. However, the main components of the gut contents were different between two species, though this was probably due to differences in spatial distribution patterns of gobies and their prey items. In conclusion, both the gavelin goby and the fine spot goby, despite being the related species and co-inhabiting the similar part of the tidal flat, had quite distinct food habits and low dietary overlap (Schoener's index: 0.4). These indicated that the two gobies are or were partitioning resources in space and time for maximum uitilization of available food.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.746-753
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• 2013

The aim of this study was to evaluate artificial fish shelter, which was known to increase prey survival and expand habitat space to improve species diversity and fish communities in a freshwater ecosystem. The experiment was performed at an outdoor test-bed for three months from 2011 by comparing the responses to adjustments in the volume of the artificial patch (juvenile fish shelter, JFS) in the control and experimental groups. Analysis of the environmental conditions over two periods (Period1 ~ 2) showed minor differences in the physichemical characteristics of water quality, phytoplankton, and zooplankton biomass, thus, allowing comparative analysis of feeding ecology. However, high water temperature conditions in Period1 ($25.6{\pm}2.0^{\circ}C$), affected the predation activity of the piscivorous fishes, Coreoperca herzi (C. herzi, size $89{\pm}4mm$). Survival rates of the prey fishes, Rhynchocypris oxycephalus (R. oxycephalus, size $29{\pm}1mm$), improved as the patch volume increased and were higher than those of the control group by 35.9 ~ 46.7%. Analysis showed that JFS reduced the chances of predator-prey encounter, and thereby minimized prey vulnerability.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.24-31
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• 2014

This study was conducted to clarify the seasonal and elevational pattern of herbivore's feeding pattern in a temperate deciduous forest. We investigated the herbivore's feeding activity for three years (2011~2013) at three survey sites in Mt. Jirisan National Park (Piagol, Siamjae, Nogodan). We selected target tree species based on the dominance across the sites (Quercus, Acer, Rhododendron and Carpinus) and scored herbivore's feeding activity every one or two weeks from April to June using leaf damage index. We found that the herbivory started early at the low elevation site (Piagol, ${\approx}300m$), and the highest feeding activity occurred at the mid elevation site (Siamjae, ${\approx}900m$). At the highest elevation site (Nogodan, ${\approx}1300m$), the herbivory started late, but the total feeding activity accumulated quickly. Compared to the breeding time of Varied tit, an insectivore bird, it was overlapped with the feeding activity period of herbivores, suggesting close interaction among plants, insects and birds in this deciduous forest. We suggested a need of long-term monitoring of this tri-trophic interaction since duration of herbivore activity can be changed followed by climate change.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.127-134
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• 2017

This study was conducted to identify the reproductive behavior of the barn swallow. The study was carried out in Gwangju, Korea during the 2013 breeding season. In the morning, the nest-building frequency was 14.2~31.0 trips/h (10.2~19.8 trips/h by male and 4.0~11.4 trips/h by female). The nest-building activity took 7.6~15.9 min/h (4.8~8.1 min/h by male and 2.8~8.0 min/h by female). The nest-building time by female ($40.0{\pm}27.9sec/trip$) was about 1.5 times longer than the nest-building time by male ($26.1{\pm}15.5sec/trip$). Only the female incubated the eggs. The Incubation time was $50.6{\pm}17.5min/h$ (84%) at 6h, 24.5 min/h (40.8%) at 7h and 15.6 min/h (26.0%) thereafter. During daytime, the female incubation time showed a highly significant difference (p<0.001), and the incubation time at 6h was higher than that at other times. There was a significantly negative correlation between female incubation time and the mean air temperature(p<0.05). The frequency of feeding was $385.2{\pm}66.9trips/nest$ in the daytime ($219.2{\pm}37.1trips/nest$ by male and $166.0{\pm}30.8trips/nest$ by female). The frequency of feeding per hour was $32.1{\pm}12.3trips/h$ ($18.3{\pm}7.8trips/h$ by male and $14.3{\pm}4.5trips/h$ by female). The frequency of feeding per hour showed a significant difference in the range of 10h(p<0.05) and 15h(p<0.01) by sex. The time of feeding by female ($40.9{\pm}83.3sec/trip$) was longer than the time of feeding by male ($12.3{\pm}31.0sec/trip$). The juvenile defecation frequency was $45.6{\pm}8.4times/nest$ per day and showed a positive correlation with feeding frequency (p<0.05). The results of this study will be helpful in understanding the reproductive behaviors of the swallow adapted to the environment in Korea.

• The Korean Journal of Ecology
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• v.27 no.6 s.122
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• pp.383-390
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• 2004

This study was conducted in three sites, Si-Hwa Lake, Dongman and Seoman island and Janguyeop island, from march, 1999 to september, 2002. The behaviors of pre-breeding season, territorial behaviors, reproductive ecology, foraging sites and behaviors, and the competition of reproduction and foods between intraspecific or interspecific of Eurasian Oystercatcher (Haematopus ostralegus) were observed in each studying sites. The breeding of Eurasian Oystercatcher started on the middle of April in Si-Hwa Lake and on the middle of May in Dongman and Seoman island and Janguyeop island. For intension of pair bond on pre-breeding season, Eurasian Oystercatcher foraged with pair and behaved male-female chasing flight behavior. The pair foraged with male and female before copulation. If other pairs and individuals approached in feeding site of pair, this pair attacked them with piping calling and intruder chasing flight. If continuos serial behaviors were not observed, the discrimination of male-female chasing flight and intruder chasing flight was difficult. Territorial behaviors classified four types; butterfly flight, calling behavior, chasing behavior, fight behavior. The important foraging sites in Si-Hwa Lake are the land place in Daeboo island, tidal flat of Bangameori, tidal flat a front of a stationary net for catching fishes and tidal flat a front of a view station for bird watching. Eurasian Oystercatcher foraged at tidal flat on low water of the tide and foraged at feeding sites near island on flood tide in Dongman and Seoman island. Eurasian Oystercater in Janguyeop island usually foraged feeding sites near island, because water level was not different between low water of the tide and flood tide. Eurasian Oystercatcher competed on foods of intraspecific and interspecific. They chased for taking foods by force in feeding sites and drove out intruders in feeding sites. The foods interspecific competition happened with Black-tailed Gull (Larus crassirostris). Eurasian Oystercatcher was robbed of foods and attacked by Black-tailed Gull. The individual of food competition with Black-tailed Gull was low foods intake rate comparison with other feeding sites and this individual flied out other feeding sites.

• Journal of Ecology and Environment
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• v.29 no.5
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• pp.415-424
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• 2006

The main objective of this study is to find out the fauna of macroinvertebrate and composition of functional feeding groups about the aquatic insects to microhabitat from the Geum River, Korea. This study is based on investigations of the main channel of Geum River, Korea which is upstream of Daecheong Dam, and carried out in the spring and autumn of 2004. Collections from all the sites were 39,532 individuals, 130 species, 54 families, 16 orders, 7 classes, and 4 phyla of macroinvertebrates. Aquatic insects were composed of 90.76% (118 species) and 98.88% (39,088 individuals) of all the identified species. Among the microhabitats, the riffles were collected 26,293 individuals and 92 species, and the runs were collected 12,329 individuals and 89 species. Finally, the pools were collected 494 individuals and 41 species. In this survey, the proportions of functional feeding groups of aquatic insects were as follows (percent of identified): predators 37.65%, gathering-collectors 23.53%, scrapers 16.47%, filtering-collectors 11.76%, shredders 9.41% and plant-piercers 1.18%. Also, the functional feeding groups were sorted according to microhabitat, in the riffles 30.65% were predators and 29.03% were gathering-collectors; in the run 30.3% were predators, and 28.79% were gathering-collectors; while in the pools 36.67% were predators, and 30.0% were gathering-collectors. In all microhabitats, gathering collectors and predators were predominant, because most of the survey sites are in the midstream. Also, the scrapers were shown more frequently in the riffle (17.74%) and run (18.18 %) than pool (13.13%), the filtering-collectors were shown more frequently in the riffle (14.52%) and the run (12.12%) than the pool (6.67%), and the plant-piercers (3.33%) were found only in pools. But the shredders weren't a difference in the run (10.61%), the pool (10.0%) and the riffle (8.06%), because of the characteristic. Microhabitats (riffle and run) are much alike in composition ratio of functional feeding groups and pool was very lower out of composition ratio in microhabitats. But riffle is very important than run, because most of individual occur in streams. Besides, pool was diverse to composition ratios, considering the number of individuals.

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.197-206
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• 2009

Benthic macroinvertebrate communities were collected from six different sites in the Dobong Stream in Seoul, Korea to investigate spatial and temporal changes in benthic macroinvertebrate communities in response to natural disturbances such as floods and droughts. We collected samples monthly or semimonthly with a Surber net ($30cm{\times}30cm$), and measured environmental factors, including stream temperature, discharge, width, conductivity, dissolved oxygen and pH at each sampling site. Benthic macro invertebrates were strongly affected by floods as well as droughts. In addition, benthic macroinvertebrate communities displayed different responses to the onset of the rainy season in summer 2006 and 2007, apparently due to differences in the intensity and amount of precipitation. Chironomids were particularly sensitive to heavy rain. Floods and droughts also affected the proportions of functional feeding groups during the survey period: the proportion of scrapers was high right after heavy rains, while the proportion of predators tended to increase in intermittent-type streams as the riffle zone decreased. Finally, although species richness and abundance were strongly influenced by heavy rain, they recovered to background levels for within one month, and varied consistently among stream types, indicating habitat stability.

• The Korean Journal of Ecology
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• v.23 no.2
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• pp.181-185
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• 2000

This study was carried out to see whether Gastrophysa viridula (Degeer) (Coleoptera : Chrysomelidae) could be used as a biological control agent for Rumex obtusifolius L., with human manipulation of the beetle population. The study was consisted of three experimental sets : Wet-Dry experiment (the wet weight Vs dry weight relationship of Rumex obtusifolius L.), Greenhouse feeding experiment, and Field experiment. There was a significant correlation between the total wet and dry weight of Rumex obtusifolius as follows : Total dry weight : -0.23542+ (0.17514${\times}$Total wet weight) ($R^2$=0.9317, p=0.047, T=16.927 (dF=21)). In the Greenhouse feeding experiment, the result was very promising. The relationship between the density unit of the beetles and the growth of the plant is given below (20 day) : Plant growth =105.8+(-34.4${\times}$Density unit) ($R^2$=0.76, p=0.13). A repeated introduction of the beetle population into the field vegetation of R. obtusifolius from April to October is suggested to see the beetle's grazing ability on the plant. This study shows that the potential grazing power of the beetle on Rumex obtusifolius was enough to defoliate the plants, but it was able to recover from its root reserves. The practical question remains as to whether repeated additions (by man) of the beetles to Rumex obtusifolius could eliminate them.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.337-342
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• 2016

Sea cucumbers have been an important part of human diets throughout history; demand is increasing every year, making the species a target for coastal resource development. New harvesting technologies have been developed in response to demand, including nursery production and insemination aquaculture, but such methods produce relatively few individuals and productivity per unit area is very small. For example, captures are prohibited during July and August due to the breeding season, and sea cucumbers aestivate during the hot season and hibernate during the cold season, all factors that limit natural-environment production in Korea. Problems with slow growth of sea cucumbers have been encountered in previous rearing experiments. To assess the importance of feeding ecology on sea cucumber growth, we conducted pond-bottom and lantern-net culture experiments. Results showed that sea cucumbers in bottom cultures grew from 3.06 to 102.59 g, but those in lantern cultures only grew from 25.60 to 28.03 g.