• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.319-322
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• 1983

Species-area and species-quadrat number curves were used to determine the minimum sampling size and the minimum quadrat number for weed data collection in transplanted rice. In both cases, characteristic curves that first increased abruptly and then leveled off as fewer species were added with increased sampling size or quadrat number were obtained. Using these techniques, it was determined that three quadrats each 0.3㎡ (0.5m ${\times}$0.6m) in area were needed to adequately represent the weed community when it was sampled at rice heading.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.313-324
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• 2010

With growing interest in biodiversity in rice paddies, efficient sampling methods for quantitative evaluation of aquatic macroinvertebrates are needed because of their important role in rice paddies' food webs. For this reason, we sought a proper sampling method through comparing data collected by using aquatic net, quadrat, and core in rice paddies located in Chuncheon-si, Kangwon-do, Hongseong-gun, and Chungcheongnam-do. Because the frame of the net was rectangular and had a flat bottom, the area, sampledwith the aquatic net, was calculated by multiplying the net width by the sweeping length, All samples were taken from the space between the rows of rice plants. Twenty four taxa of macro invertebrates were collected in Chuncheon and 28 taxa in Hongseong. In Chuncheon, the number of taxa was similar among three sampling methods (17-18 taxa), but the number of individuals was different (aquatic net, $1,317/m^2$; quadrat, $1,368/m^2$; core, $1,810/m^2$. In Hongseong, the number of taxa sampled by aquatic net was the highest (aquatic net, 25 taxa; quadrat, 21 taxa; core, 16 taxa), but the core was the highest in the number of individuals (aquatic net, $1,586/m^2$; quadrat, $2,595/m^2$; core, $3,704/m^2$. The efficiency of samplers differed among taxa. Most of aquatic insect taxa were more abundant in the aquatic net, while those living on or in the paddy substratum such as Oligochaeta and Chironomidae were collected more in the quadrat sampler. To collect quantitative data for aquatic insects as well as to produce inventory of rare taxa, we suggest, based on samplers used in this study, to take quantitative samples of 6 replications from each of the edge and inner zones of a rice paddy by using an aquatic net, and to take qualitative samples both from sides of levees and the inner zone of rice paddy by using an aquatic net.

• The Korean Journal of Malacology
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• v.30 no.1
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• pp.95-99
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• 2014

In the present study, we surveyed the molluscan fauna in a lagoon located near Seong-san harbor on the east coast of Jeju Island in July 2012. For the survey, a $25{\times}25cm$ quadrat was deployed over 3 randomly selected sites in the intertidal area of the lagoon. Sediment from the surface to a depth of 25 cm in the quadrat was removed and sieved using a 1 mm mesh sieve. All molluscan fauna retained on the sieve was identified to the species level. From the survey, 25 species of mollusca belonging to 2 orders and 16 families were identified. Species richness, in terms of total number of species, was found to be the highest at sampling site 1, where the substrate was composed of coarse sand and some rocks, while it was lowest at sampling site 3, composed of compact fine sand. Regardless of the type of substrate at the sampling sites, the mud-creeping snail Batillaria cumingii (Crosse, 1862) occurred at a high density, ranging from $324-468ind./m^2$. The luciniid bivalve Pillucina pisidium also occurred at a high density at sampling site 1, at $336ind./m^2$, while the density of this species was only $4ind./m^2$ at sampling site 3. The Manila clam Ruditapes philippinarum could be found at all 3 sampling sites with very low density ranging from $16-48ind./m^2$. The density and species richness of molluscs observed in this study was lower compared to the previously reported molluscan fauna in Jeju Island, suggesting that further investigation needs to be carried out to conserve the unique marine lagoon ecosystem in Jeju Island.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.278-291
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• 2024

This study performed three research methods (destructive, non-destructive, and panoramic image analysis) to determine the most useful for identifying seaweed habitat characteristics. Panoramic images are suitable for understanding the overall seaweed distribution. The composition of the main dominant seaweed species showed a significant difference between the destructive and non-destructive methods using Quadrat. The destructive method showed Rhodophyta dominance, whereas the non-destructive was showed Phaeophyta as dominant. Destructive methods are disadvantageous because they destroy natural communities in sea areas where bleaching is severe. Non-destructive methods are disadvantageous because of the difficulty in analyzing small species. Performing 10 surveys using a non-destructive method was found to explain up to 80% of the species identified by the destructive method. However, considering the difficulty of field investigation, repeating the investigation with non-destructive methods at least 6-7 times is necessary to ensure that more than 60% of the destructive methods can be interpreted. To understand the distribution of oceanic marine algae, performing both destructive and non-destructive surveys are necessary, as each has its own merits and demerits.

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.183-190
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• 2019

Background: In the Philippines, the practice of planting mangroves over seagrass has been a practice done to promote coastline protection from damages done by storms. Despite the added protection to the coastline, the addition of an artificial ecosystem gradually inflicts damage to the ecosystem already established. In this study, seagrass communities that had no history of mangrove planting were compared with those that had mangrove planting. The percent substrate cover of seagrass in the sampling areas was determined, and the macroinvertebrates present in the sampling areas were also observed. The study was conducted based on reports of mangrove planting activity that disrupted seagrass functions on Santa Fe, Bantayan Island, Cebu. Transect-quadrat method sampling was done to assess the chosen sites. Results: Six species of seagrass was found on the site without mangrove planting which was barangay Ocoy (Cymodocea sp., Thalassia sp., Halodule sp., Enhalus sp., Halophila sp., and Syringodium sp.) and had a higher percent cover, while only four were found on the site with mangrove planting (barangay Marikaban). It was also found that barangay Marikaban had a lesser Shannon-Wiener and Simpson's index compared to barangay Ocoy. Jaccard's index of similarity between the two sites was low. Conclusion: With the results of the assessment, we recommend proper monitoring of future mangrove planting activities and that these activities should not disrupt another ecosystem as all ecosystems are important.

• ALGAE
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• v.23 no.4
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• pp.289-294
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• 2008

To estimate seaweed biomass or standing crop, a nondestructive sampling can be beneficial because of not much destroying living plants and saving time in field works. We suggest a methodological procedure to estimate seaweed biomass per unit area in marine benthic habitats by using species-specific regression equations. Percent cover data are required from the field samplings for most species to convert them to weight data. However, for tall macroalgae such as kelps we need density data and their size (e.g., size class for subtidal kelps) of individuals. We propose that the field sampling should be done with 5 replicates of 50 cm x 50 cm quadrat at three zones of intertidals (upper, middle, lower) and three depth points (1, 5, 10 m) in subtidals. To obtain a reliable regression equation for a species, a substantial number of replicate is necessary from destructive samplings. The regression equation of a species can be further specified by different locality and different season, especially for the species with variable morphology temporally and spatially. Example estimation carried out in Onpyung, Jeju Island, Korea is provided to compare estimated values with real weight data.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.640-647
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• 2017

The need for an efficient sampling technique to collect aquatic organisms has risen with the increase of interest in rice paddy fields, which have been recognized as important ecosystems supporting biodiversity. In the present study, a submerged funnel trap used with the assistance of attracting agents (fish meal and chemical light) was designed as an easy, objective and quantitative tool for collecting aquatic organisms in the rice paddy fields. The preference for collecting aquatic organisms as a means for attracting agents was analyzed using a generalized linear mixed model. Also, based on the data of previous research, we compared the community composition of the aquatic macroinvertebrates, which were collected using the quadrat method, and newly designed submerged funnel traps, by analyzing non-metric multidimensional scaling. The results showed that the catching efficiency of 18 of the total 65 taxa was affected by the attracting agents. 12 taxa including Pomacea canaliculata, Hippeutis cantori, Austropeplea ollula, Erpobdella lineata, Ostracoda spp. Branchinella kugenumaensis, Hydaticus grammicus, Rhantus pulverosus, Chironomidae spp., Rana nigromaculata, Cobitidae spp. etc., favored fish meal and 6 taxa including Ischnura asiatica, Coenagrionidae spp. Sternolophus rufipes etc., were attracted by chemical light. The submerged funnel trap used as a measurement tool for biodiversity was less applicable than the quadrat method; however, it was more effective for the selective collection of specific taxa. We expect that this newly designed trap can be a simple and quantitative method for collecting aquatic organisms, and could be used for long term and extensive surveys in rice paddy fields in the future.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.99-106
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• 2018

Extensive monitoring of aquatic organisms in rice paddy fields has been difficult due to laborious sampling methods such as quadrat sampling using a hand net. This study aimed to analyze temporal and regional community compositions of aquatic organisms collected with a less time-consuming sampling method. This method involved using submerged funnel traps in rice paddy fields. Submerged funnel traps were useful for capturing taxa containing species that are indicative of environmental changes and highly mobile species that feed on waterbirds. Fifteen taxa including Ampullariidae, Cobitidae, Chironomidae, Hydrophilidae and Dytiscidae determined the community compositions. Among the major taxa, only Chironomidae resistant to environmental disturbances represented temporal variations of aquatic organism communities in rice paddy fields. Ampullariidae, Dytiscidae, and Hydrophilidae, which are prone to be affected by anthropogenic activities, differed among regions.

• ALGAE
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• v.23 no.4
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• pp.327-334
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• 2008

Seaweed biomass was estimated using a nondestructive sampling method in the rocky intertidal and subtidal zone in Daejin on the mid-east coast of Korea from August 2006 to April 2008. Seasonal sampling were done at the depth of 0, 1, 5, 10 m using 50 x 50 cm quadrat. A total of 95 species, including 11 chlorophytes, 26 phaeophytes, 57 rhodophytes and one sea grass were identified. Mean biomass was comprised of 1,292 g wet wt m$^{-2}$ and the biomass values varied seasonally from 904 g to 1,945 g. Dominant species in biomass were Sargassum spp. (S. horneri, S. yezoense), Corallina pilulifera, Phyllospadix japonica, Symphyocladia latiuscula, Hizikia fusiformis, Codium arabicum and Chondrus ocellatus at Daejin. The vertical distribution of algae were characterized by Corallina pilulifera, Symphyocladia latiuscula, Sargassum spp. (S. confusum, S. yezoense), Hizikia fusiformis and Grateloupia elliptica at intertidal zone, Sargassum spp. (S. fulvellum, S. horneri, S. yezoense), Phyllospadix japonica, Codium arabicum, Undaria pinnatifida and Corallina pilulifera at 1 m depth, Sargassum spp. (S. horneri, S. micracanthum, S. yezoense), Phyllospadix japonica, Grateloupia elliptica, Gelidium amansii and Codium arabicum at 5 m depth and Phyllospadix japonica, Codium arabicum, Sargassum spp. (S. horneri, S. micracanthum, S. yezoense) and Undaria pinnatifida at 10 m depth.

• ALGAE
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• v.23 no.4
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• pp.311-316
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• 2008

The seasonal variation of marine algal biomass and community were studied with nondestructive sampling and quadrat method during May 2006 to April 2008 in the intertidal and subtidal zone at Yokjido. As result, total 120 species, 13 Chlorophyta, 34 Phaeophyta, 71 Rhodophyta and 2 Spermatophyta were identified in this study. The major species which contributed significantly to the total biomass were Ulva pertusa, Undaria pinnatifida, Ecklonia stolonifera, Sargassum horneri, S. serratifolium, Gelidium amansii and Prionitis cornea. The mean biomass was 235.5 g wet wt m$^{-2}$ in intertidal, 1,038.9 g wet wt m$^{-2}$ in 1 m, 1,013.1 g wet wt m$^{-2}$ in 5 m, and 19.7 g wet wt m$^{-2}$ in 10 m depths of mean sea level. Seasonal biomass change in intertidal zone, the peak season was in spring, while the lowest was in autumn. The vertical distribution of marine vegetation was characterized by Ulva pertusa - Gelidium divaricatum - Gloiopeltis furcata - Sargassum thunbergii - Hizikia fusiformis at intertidal zone, and Caulerpa okamurae - Gelidium amansii - Chondrus ocellatus - Ecklonia stolonifera - Sargassum horneri - Gracilaria textorii at subtidal zone. These result indicates that the marine algal species and biomass of 1 m and 5 m depths in subtidal zone are greater than intertidal zone, and Ecklonia stolonifera and Sargassum spp. are the dominant species of Yokjido.