• ALGAE
• /
• 제17권2호
• /
• pp.71-74
• /
• 2002

Zostera geojeensis, a new species from Geojedo Island located on the south coast of Korea, is described and compared with othe rrelated species of Zostera. It is very similar to Z. caespitosa Miki in having congested internodes of rhizomes but differes from that by having obtuse or cuspidate and transparent leaf margins at apices.

• ALGAE
• /
• 제20권4호
• /
• pp.379-388
• /
• 2005

Seagrass bed is an important component in coastal and estuarine ecosystems, providing food and shelter to a wide variety of fauna. Recently, seagrass coverage has declined significantly due to anthropogenic influences such as reclamation, dredging, and eutrophication and consequently, necessity of seagrass habitat restoration is rising. Transplantation experiments with Zostera marina using TERFS, staple method, and shell method have been conducted at Dadae Bay, Kosung Bay and Jindong Bay on the south coast of Korea to select an optimal transplanting method for restoration of Z. marina habitat. Three experimental sites located at the vicinity of natural Z. marina beds with an average water depth of about 4m. Z. marina plants, which were collected from donor bed in Koje Bay were also transplanted at 7 different time from October 2003 to July 2004 to find appropriate transplanting time. Density of Z. marina was monitored monthly at both transplanted areas and natural beds. Transplantation using the staple method showed the highest survival rate of transplant. Shell method was also an effective transplanting method at muddy areas in Kosung Bay and Jindong Bay, but not suitable at sandy areas in Dadae Bay. These results suggest that sediment composition of transplanting areas should be considered for the selection of the optimal transplanting method. Z. marina transplanted during fall usually showed the highest survival rate, while most Z. marina plants transplanted in summer died due to high lethal temperature during this period.

• Ocean and Polar Research
• /
• 제35권4호
• /
• pp.441-452
• /
• 2013

The fish species composition of seagrass bed in Chuuk Lagoon, Micronesia, was investigated every month from August 2009 to July 2011, using a seine net for fish caught. A total of 32 fish species belonging to 18 families under 6 orders were identified during the study period. Of these fish, Atherinomrus lacunosus, and Strongylura incise were the major dominant species representing 85.0% in total number of individuals. The number of species and individuals were high from August to December 2009, 2010. The biomass was highest in September 2010 and the diversity index was higher in September 2009, April, August 2010 and July 2011. The 14 dominant species could be divided into 2 groups of 3 individuals based on appearance patterns; (1) resident species and temporal species (9 species, e.g. Atherinomrus lacunosus), juvenile and adults living in seagrass beds and juveniles living only in seagrass beds; (2) temporal species (2 species, e.g. Hemiramphus lutkei), juveniles living only in seagrass beds; (3) temporal species (3 individuals, e.g. Caranx sexfasiatus). For some species, the appearance patterns were affected by water temperature. However, the relationships between sea currents, salinity, tide, and structure of fish assemblage remain unclear. Further studies that regularly monitor sea grass habitats are necessary to clearly understand the correlation between environmental factors and sea grass habitat use patterns in fish assemblages.

• Ocean and Polar Research
• /
• 제35권4호
• /
• pp.395-405
• /
• 2013

The aim of this study is to suggest an optimal survey method for coastal habitat monitoring around Weno Island in Chuuk Atoll, Federated States of Micronesia (FSM). This study was carried out to compare and analyze differences between in situ survey (PHOTS) and high spatial satellite imagery (Worldview-2) with regard to the coastal habitat distribution patterns of Weno Island. The in situ field data showed the following coverage of habitat types: sand 42.4%, seagrass 26.1%, algae 14.9%, rubble 8.9%, hard coral 3.5%, soft coral 2.6%, dead coral 1.5%, others 0.1%. The satellite imagery showed the following coverage of habitat types: sand 26.5%, seagrass 23.3%, sand + seagrass 12.3%, coral 18.1%, rubble 19.0%, rock 0.8% (Accuracy 65.2%). According to the visual interpretation of the habitat map by in situ survey, seagrass, sand, coral and rubble distribution were misaligned compared with the satellite imagery. While, the satellite imagery appear to be a plausible results to identify habitat types, it could not classify habitat types under one pixel in images, which in turn overestimated coral and rubble coverage, underestimated algae and sand. The differences appear to arise primarily because of habitat classification scheme, sampling scale and remote sensing reflectance. The implication of these results is that satellite imagery analysis needs to incorporate in situ survey data to accurately identify habitat. We suggest that satellite imagery must correspond with in situ survey in habitat classification and sampling scale. Subsequently habitat sub-segmentation based on the in situ survey data should be applied to satellite imagery.

• 한국해양학회지
• /
• 제21권1호
• /
• pp.25-33
• /
• 1986

미국 Texas 남쪽 해안에 위치한 Redfish Bay의 해초생태계에 우점종으로 나 타나는 4어종인 darter goby(Gobionellus bolesoma), pinfish(Lagodon rhomboides), code goby(Gobiosoma robustum), 그리고 Gulf pipefish(Syngnathus scovelli)에 대 한 성장에 따른 먹이 선택의 변화를 정량적으로 연구하였다. 가장 우점종인 darter goby는 비교적 다양한 먹이를 먹는 잡식성 어류로 amphipods, copepods, polychaetes, filamentous algae, diatoms 그리고 detritus등이 주된 먹이였다. 이 종 은 성장에 따른 먹이 선택의 변화가 크지 않았다. 반면에 pinfish, code goby 및 Gulf pipeifish는 성장함에 따라 먹이 종류가 크게 달라졌다. pinfish의 경우, 4단계 의 먹이 선택의 변화를 보이는데, 초기에는 육식성으로 주로 copepods를 섭식하였 으나, 조금 성장하면 주된 먹이가 amphipods로 바뀌며, 조금 더 성장하면 잡식성으 로 변해 filamentous algae, diatoms, amphipods 그리고 aolychaetes등의 다양한 먹 이를 먹으며, 그후 더욱 성장하면 seagrass와 seagrass위에 붙어있는 algae 그리고 그들의 debris를 주로 먹는 초식성으로 먹이 습성이 바뀌었다. code goby 와 Gulf popefish 는 비교적 적은 종류의 동물성 먹이에만 의존하는 육식성 어류들이었다.또한 두조은 비슷한 성장에 딸느 먹이 선택의 변화를 보이는데,초기에는 주로 copepods 를 섭이하였으나 성장함에 따라 점진적으로 보다 큰 amphipods로 먹이 선택이 바뀌었다.

• ALGAE
• /
• 제23권3호
• /
• pp.241-250
• /
• 2008

Since seagrasses in the coastal and estuarine ecosystems achieve high levels of production, they require high inorganic carbon and nutrient incorporation. Thus, seagrasses may play a significant role in carbon and nutrient cycling in the coastal and estuarine ecosystems. To examine growth dynamics of Zostera marina L. environmental factors such as underwater irradiance, water temperature, and salinity, and biological parameters such as shoot density, biomass, shoot morphology, and leaf productivity were measured in two bay systems (Jindong Bay and Gamak Bay) on the southern coast of Korea. While underwater irradiance did not show distinct seasonal trend, water temperature at both sites exhibited clear seasonal trend throughout the experimental period. Shoot density increased dramatically during winter due to the increased seedlings through germination of seeds in Jindong Bay and due to the increased lateral shoots in Gamak Bay. Eelgrass biomass increased during winter and decreased during summer. Maximum biomass in Jindong Bay and Gamak Bay was 250.2 and 232.3 g dry weight m–a2, respectively. Carbon incorporation into the eelgrass leaf tissues was estimated from productivity and leaf tissues carbon content. The calculated annual carbon incorporations at the Jindong Bay and Gamak Bay sites were 163 and 295 g C m–`2 y–`1, respectively. This high carbon incorporation into seagrass tissues suggests that seagrass habitats play an important role as a carbon absorber in the coastal and estuarine ecosystems.

• 한국환경농학회지
• /
• 제41권1호
• /
• pp.50-54
• /
• 2022

BACKGROUND: Phyllospadix japonica Makino is a perennial plant belonging to the family Zosteraceae. This species is native to the eastern coast of the Korean Peninsula, and it is found attached to rocks on the seashore. As with all seagrass species, P. japonica is also known to play a major role in protecting the marine environment, and studies on its physiological activities suggestive of its antioxidant, antibacterial and anti-inflammatory potentials have been reported. In this study, purification and structural analysis were performed to identify the polyphenol substances derived from P. japonica. METHODS AND RESULTS: An polyphenol substance MP-1 was purified from the 70% aqueous methanol extract of P. japonica using Diaion® HP-20 column chromatography, ODS column chromatography, and medium-pressure liquid chromatography (MPLC). The purified MP-1 was identified as rosmarinic acid having a molecular weight of 360 and a molecular formula of C18H16O8 through electrospray ionization (ESI)-mass and nuclear magnetic resonance (NMR) spectroscopic analysis. CONCLUSION(S): This study highlights the processes used for the identification of the polyphenol substance derived from P. japonica. Rosmarinic acid, the polyphenol derived from P. japonica identified by this study, is a kind of bioactive substance mainly present in plants. These findings provide an important starting point and are valuable for future studies on bioactive substances in seagrass.

• ALGAE
• /
• 제20권2호
• /
• pp.157-166
• /
• 2005

Uptake kinetics of Cd and Zn by leaves and rhizome of the seagrass Zostera marina were examined in controlled laboratory radiotracer experiments. Subsequently, acute toxicity of Cd, Cu and TBT on photosynthetic quantum yield (ΔF/Fm’ of Z. marina were determined, and the differential sensitivities of rapid light curve (RLC) to those harmful substances were also compared. All measurements on photosynthetic activity were determined by chlorophyll a fluorescence method using pulse amplitude modulation (PAM). Metal uptake by Z. marina was saturated with increasing exposure time in leaves and rhizomes. Uptake of Zn by Z. marina was faster than that of Cd. Metal uptake rates in Z. marina decreased with the increase of dissolved metal concentrations and also with the increase of biomass. The adverse effect of TBT on effective quantum yield was stronger than other pollutants. Average acute toxicity on the RLC of the seagrass exposed to TBT and two heavy metals (Cd and Cu) was going to decrease as follows: TBT > Cd > Cu. Our preliminary results in this study suggested that Z. marina potentially can be used as a biomonitor of harmful substances contamination in coastal waters.

• 한국어류학회지
• /
• 제13권4호
• /
• pp.223-229
• /
• 2001

오스트레일리아의 Queensland에 위치한 Cockle Bay의 해초지에서 채집된 Sillago maculata의 식성을 조사하였다. S. maculata (0.5~9.5 cm SL)의 주요 먹이생물은 단각류에 속하는 옆새우류, 게류 및 요각류였으며, 그 외 갯지렁이류, 새우류, 어류, 등각류, 쿠마류 등이 소량씩 위내용물 중에서 발견되었다. S. maculata은 성장함에 따라 먹이생물의 조성이 점차 변하였다. 체장이 작은 개체는 요각류, 게의 유생, 옆새우류를 주로 먹었으나, 체장이 증가하면서 요각류 및 게 유생의 비율은 점차 낮아진 반면, 갯지렁이류 및 어류가 차지하는 비율은 증가하였다. 한편 옆새우류는 조사된 모든 크기에서 가장 선호하는 먹이생물이었다.

• 대한원격탐사학회지
• /
• 제36권2_1호
• /
• pp.199-215
• /
• 2020

잘피는 연안해역에 서식하는 해양수생관속식물로 해양생태계의 중요한 역할을 하고 있어, 주기적인 잘피 서식지의 모니터링이 이루어지고 있다. 최근 효율적인 잘피 서식지의 모니터링을 위해 고해상도의 영상 획득이 가능한 드론의 활용도가 높아지고 있다. 그리고 의미론적 분할에 있어 합성곱 신경망 기반의 딥러닝이 뛰어난 성능을 보임에 따라, 원격탐사 분야에 이를 적용한 연구가 활발하게 이루어지고 있다. 그러나 다양한 딥러닝 모델, 영상, 그리고 하이퍼파라미터에 의해 의미론적 분할의 정확도가 다르게 나타나고, 영상의 정규화와 타일과 배치 크기에서도 정형화되어 있지 않은 상태이다. 이에 따라 본 연구에서는 우수한 성능을 보여주는 딥러닝 모델을 이용하여 드론의 광학 영상에서 잘피 서식지를 분할하였다. 그리고 학습 자료의 정규화 및 타일의 크기를 중점으로 결과를 비교 및 분석하였다. 먼저 정규화와 타일, 배치 크기에 따른 결과 비교를 위해 흑백 영상을 만들고 흑백 영상을 Z-score 정규화 및 Min-Max 정규화 방법으로 변환한 영상을 사용하였다. 그리고 타일 크기를 특정 간격으로 증가시키면서 배치 크기는 메모리 크기를 최대한 사용할 수 있도록 하였다. 그 결과, Z-score 정규화가 적용된 영상이 다른 영상보다 IoU가 0.26 ~ 0.4 정도 높게 나타났다. 또한, 타일과 배치 크기에 따라 최대 0.09까지 차이가 나타나는 것을 확인하였다. 딥러닝을 이용한 의미론적 분할에 있어 정규화, 타일의 배치 크기의 변화에 따른 결과가 다르게 나타났다. 그러므로 실험을 통해 이들 요소에 대한 적합한 결정 과정이 있어야 함을 알 수 있었다.