• ALGAE
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• v.33 no.2
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• pp.167-180
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• 2018

Benthic diatoms are ubiquitous in tidal flats and play major roles in maintaining coastal ecosystems. Spatio-temporal variations in diatom diversity have not been well-studied, mainly because of difficulties in morphological identification and the lack of appropriate genetic tools. To overcome these problems, we used the gene encoding the ribulose bisphosphate carboxylase large-subunit (rbcL) as a molecular marker, and sequenced these genes with the aid of the MiSeq platform. In this manner, we explored the genetic diversity of benthic diatoms in tidal flats of Guenso Bay on the west coast of Korea; differences in the spatial distributions of benthic diatoms were evident. The diatom communities were dominated by Nitzschia, Navicula, and Amphora; their relative distributions were affected by the sand proportion, grain size, and air exposure time. Our results suggest that meta-barcoding of the rbcL gene and next-generation sequencing can be used to explore the diversity of benthic diatoms.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.347-370
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• 2013

A study on the presence of benthic dinoflagellates in the intertidal zone along the coasts of Jeju Island, Korea was conducted during 2011 and 2012. Identification and taxonomic observations were made of the benthic dinoflagellate samples using light and epifluorescence microscopy. Thirty-seven dinoflagellate taxa belong to five orders, nine families, 18 genera and 30 species, which are new records for Korean waters, were detected in this study. The detailed nomenclature, references, distribution, and illustrations are presented here. The commonly occurring genera were Amphidinium, Coolia, Ostreopsis, Prorocentrum, and Thecadinium. Among the recorded species, 26 were found only in sand sediment, seven in macroalgal samples, and four were found in both sand and macroalgal samples. Of the 37 species, nine were potentially toxic. These results suggest that diversified benthic dinoflagellates including several potentially toxic species occur in sand sediment and macroalgae in the intertidal zone along the coasts of Jeju Island. The morphological features of the identified species were more or less similar to observations made by previous studies in Korea and elsewhere. The presence of known toxic species may indicate a potential risk of toxicity in the marine ecosystem of Jeju Island. The present study can be helpful for further detailed taxonomic, toxicological, molecular phylogenetic studies and may help in the management and conservation of Jeju Island's marine ecosystem.

• Ocean and Polar Research
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• v.28 no.4
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• pp.369-383
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• 2006

The Saemangeum project is one of the biggest reclamation efforts in Korea and may cause coastal ecosystem change due to altered environments and habitat loss. Since February 2002, benthic environment and community structure in the Saemangeum studied area were studied to assess the influence of the project on macrofaunal community. The result of seasonal study from February, 2002 to August 2005 is reported here. Overall, changes of species numbers and dominant species of benthic animals in the periods before (1988) and after $(2002{\sim}2005)$ the Saemangeum dike construction were not evident both inside and outside the dike. However, local environmental and community change were noted The partial completion of Saemangeum dike $(4^{th}\;dike)$ in June 2003 altered water circulation and sediment deposition patterns both inside and outside the dike. Fine sediment was accumulated inside and outside the $4^{th}$ dike while coarse sediment dominated near the main channel (Sinsi gate). Benthic community resl)ended to the altered sediment type in these areas. Species number and diversity in both site was low compared to other sites. The dominant species in these areas were composed of the benthos that had not commonly occurred in the Saemangeum subtidal area.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.909-919
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• 2023

Benthic marine invertebrates, the invertebrates living on the bottom of the ocean, are an essential component of the marine ecosystem, but excessive reproduction of invertebrate grazers or pirate creatures can cause damage to the coastal fishery ecosystem. In this study, we compared and evaluated You Only Look Once Version 7 (YOLOv7), the most widely used deep learning model for real-time object detection, and detection tansformer (DETR), a transformer-based model, using underwater images for benthic marine invertebratesin the coasts of South Korea. YOLOv7 showed a mean average precision at 0.5 (mAP@0.5) of 0.899, and DETR showed an mAP@0.5 of 0.862, which implies that YOLOv7 is more appropriate for object detection of various sizes. This is because YOLOv7 generates the bounding boxes at multiple scales that can help detect small objects. Both models had a processing speed of more than 30 frames persecond (FPS),so it is expected that real-time object detection from the images provided by divers and underwater drones will be possible. The proposed method can be used to prevent and restore damage to coastal fisheries ecosystems, such as rescuing invertebrate grazers and creating sea forests to prevent ocean desertification.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.409-416
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• 2003

Marine populations are maintained through the processes of spawning, growth, recruitment, natural death and fishing in a marine ecosystem. Based upon each of these processes, a quantitative population dynamic model was developed to estimate damages in fishery production due to accidents in a fishing ground. This model was applied for the abalone culture grounds in Korean waters. Three components of damages were identified in the ecosystem of the abalone culture grounds, namely, physical damages in the substratum of the fishing ground, biological damages in the structure and function of the ecosystem, and damages in fishery production. Considering these three components the processes and durations of damages in fishery production were determined. Because the abalone population is composed of multiple year classes, damages influence all the year classes in the population, when they occur The model developed in this study is: $$y=(n_{\lambda}+1){\times}Y_E\;-\;\sum\limits^{n_\lambda-n_c}_{l=0}\;y_{n_c/i}$$ where, y is the expected damages in fishery production during the period of restoration of the damaged abalony population, $Y_E$ is the annual equilibrium yield, $n_{\lambda}$ is the maximum age in the population, $t_s$ is the year of damage occurrence, $n_c$ is the age at recruitment, and $\sum\limits^{n_\lambda-n_c}_{l=0}\;y\;_{n_c/i}$ is total expected lifetime catch of year classes which were recruited during the restoration period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.6
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• pp.694-703
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• 2012

To understand the characteristics of sedimentary and benthic environments in habitats of naturally-occurring intertidal benthic macroalgae, various geochemical parameters of sediment (grain size, ignition loss [IL], chemical oxygen demand [COD], and acid volatile sulfur [AVS]) and pore water (temperature, salinity, pH, and nutrients) were measured in the southern intertidal zone of Hampyeong Bay at two month intervals from April to October 2009. Ecological characteristics including the distribution and biomass of benthic macroalgae were also investigated. Benthic macroalgae were distributed below 4 to 5 m depth from mean sea level near the lower portion of the intertidal zone where air exposure time is relatively short. The distribution area and biomass of benthic macroalgae gradually decreased during the study period. The surface sediments in the benthic algal region were mainly composed of finer sediments, such as slightly gravelly mud and mud. The temperature, salinity, pH, and nutrient concentrations (except dissolved inorganic nitrogen) in pore water did not differ in regions with and without benthic macroalgae, whereas the mean grain size and the concentrations of IL, COD, and AVS in sediments were much higher in regions harboring benthic macroalgae. The correlation between mean grain size and IL in sediments displayed two distinct gradients and the slope was much steeper in regions harboring benthic macroalgae, indicating that the content of organic matter in benthic algal region is not solely dependent on mean grain size. Our results indicate that the benthic macroalgae in the southern intertidal zone of Hampyeong Bay play an important role in the accumulation of organic matter in sediment.

• Ocean and Polar Research
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• v.43 no.4
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• pp.245-253
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• 2021

Surirella atomus Hustedt 1955, surirelloid diatom, were obtained from Hampyeong Bay, Mu-an, in the west coast of Korea. We describe the first record of S. atomus in Korea and report its ultrastructure and molecular characteristics for the first time. For molecular analysis, rbcL gene and cob gene were sequenced. This species is very small in size, making it difficult to observe its morphological features under a light microscope. Even with a scanning electron microscope, it has no unique structure in the valve. It is morphologically very simple. This rare species was known as a marine benthic species. However, it appears to be widely distributed in marine, freshwater, and brackish environments according to the literature documenting this species. In terms of phylogeny, S. atomus has been tentatively linked to Petrodictyon gemma, but the phylogenetic placement of S. atomus seems to be still uncertain, in a manner that is similar to S. febigeri. However, morphological observations derived from this study suggest that this species belongs to the genus Surirella.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.129-139
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• 2008

Marine ecotoxicological standard method was applicated using marine rotifer and benthic copepod as primary consumer of marine ecosystem. Marine rotifer, Brachionus plicatilis and benthic copepod, Tigriopus japonicus were designated as standard test species with the endpoints of 24hr neonate mortality (24hr $LC_{50}$) and 48hr population growth (48hr $EC_{50}$) for rotifer, and 48hr nauplius mortality (48hr $LC_{50}$) for benthic copepod. Tests method was referred to those of ASTM (American Society for Testing and Materials) with the replacement of test species which are widely distributed in Korean waters. The two species showed a wide tolerance on salinity ($5{\sim}35\;psu$) and can be easily cultured in small space even they were not as sensitive as in the mortality test using the nauplius of marine invertebrates. However, these species revealed the significant "concentrationresponse relationship" tested with ocean disposal wastes, and reproducibility using cadmium as standard reference material between laboratories. Accordingly, these two species have good potential as test species for marine ecotoxicological test species. Also, we strongly recommend that at least one of these species be included in the test species of "battery test" in marine bioassay.

• 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.

• Journal of Species Research
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• v.9 no.4
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• pp.455-461
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• 2020

Marine benthic ciliates were collected from four rocky intertidal pools along the eastern and southern coasts of Korea from 2012-2013. Ciliate specimens were examined by observing living and stained cells. Four ciliate species were new to Korea based on morphological characteristics as follows. (1) Aspidisca polypoda (Dujardin, 1841): small bean-shaped (ca. 30 ㎛), eight conspicuous dorsal ridge, polystyla-arrangement of frontoventral cirri; (2) Epiclintes auricularis auricularis (Claparède & Lachmann, 1858): tripartite and auriform body (ca. 300 ㎛), 46 adoral membranelles, one or two frontal and 23 transverse cirri, 12 oblique fronto-midventral rows; 59 left and 71 right marginal cirri; (3) Pseudochilodonopsis marina Song, 1991: reniform body (ca. 50 ㎛), two obliquely positioned contractile vacuoles, seven left and five right kineties, five fragmented preoral kineties; (4) Dysteria semilunaris (Gourret and Roeser, 1888): oval-shaped (ca. 30 ㎛), two longitudinally positioned contractile vacuoles, conspicuous longitudinal grooves on both plates, four or five right kineties, one short row below frontoventral kineties.