Report on the acoustic target strength measurement of major Jellyfishes around coastal water, Korea

최근 전 세계에 걸쳐 해파리 대발생 현상은 북서태평양 인접 해양에서도 나타나고 있으며, 2000년 이후 우리나라 연안 해역뿐만 아니라 일본, 중국 등에 대량의 해파리가 유입되어 생태계에 직접적으로 영향을 주고 있어 해양과 관련된 산업 전반에 직․간접적으로 큰 피해를 발생시키고 있다. 본 연구에서는 최근 우리나라 연안에 대량 유입되거나 혹은 향후에 유입 가능성이 있은 해파리의 음향 탐지를 위한 핵심 자료로 활용될 음향 반사강도(acoustic target strength, TS) 측정 상황 및 예비 결과를 보고하고자 한다.해파리 음향 TS 측정은 최근 우리나라 연안에 유입되는 해파리 가운데 피해를 유발하는 보름달물해파리(A. aurita), 노무라입깃해파리(N. numurai), 유령해파리(C. nozakii), 커튼 원양해파리(D. quinquecirrha)를 대상으로 38, 120, 200, 420 kHz의 송수파기(BioSonics)를 이용하였다. 물성이 해수와 유사하여 보름달물해파리의 TS가 낮을 것으로 예측되었으나 살아있는 조건에서의 TS는 120, 200, 420 kHz에서 전체적으로 -72 ～ -63 dB 범위 내에 있어 음향탐지의 가능성이 있었으나, 38 kHz에서는 매우 낮게 나타나 유의성이 없었다. 대형 개체에 속하는 노무라입깃해파리의 TS는 보름달물해파리에 비해 상대적으로 단단한 물성과 공생하는 작은 새우 등에 의해 매우 높은 값을 가지고 있었다. 주파수 특성은 38 kHz에서 가장 강하게 나타나 평균 TS는 -40 dB까지 증가하고, 고주파로 갈수록 TS 값이 약해지는 특성을 가지고 있었다. 유령 해파리의 TS는 전체적으로 -49 ～ -54 dB의 범위 내에 존재하는 것으로 나타났으며, 평균 음향 반사강도는 38 kHz의 경우 -49 dB, 120, 200 kHz는 -53 dB, 420 kHz는 -54 dB로 상대적으로 낮은 주파수 대역에서 강하게 나타나 공생하는 샛돔 치어에 의한 영향을 받는 것으로 나타났다. 우리나라 연안에 분포하는 대표적인 해파리에 대한 음향 특성 실험 상황 및 음향 특성을 간략히 기술하였다. 이러한 자료는 향후 해파리 음향 탐지를 위한 다양한 자료로 활용 가능하며, 지속적인 음향 자료 구축이 뒤따라야 할 것이다.2

Bottom sand waves influence on low-frequency propagation in shallow water environment

For understanding characteristics of acoustic propagation in shallow water environment, reliable geoacoustic data such as bottom composition, topography, and sediment layer are necessary in theoretical and practical approach. As the full data acquisition, however, is limited in the field, it has applied to simplify the geological structures in most cases [1]. The simplification of the environment variable is limited on the analysis of the acoustic propagation and theoretical verification of the measured data in shallow water.The study area was Yellow Sea that it has a well-developed shallow continental shelf and especially strong tide. The seabed due to the strong tide has been formed various bed-form (ripple, sand wave and sand dune) along direction and strength of the tide [2]. Unlike water-sediment interface with flat bottom, the sand wave and sand dune have a strong influence on acoustic propagation, reflection and scattering.In this paper, we present the effects of low-frequency sound waves caused by sand wave zone with the acoustic transmission loss data measured in shallow waters.ta acquisition, however, is limited in the field, it has applied to simplify the geological structures in most cases [1]. The simplification of the environment variable is limited on the analysis of the acoustic propagation and theoretical verification of the measured data in shallow water.The study area was Yellow Sea that it has a well-developed shallow continental shelf and especially strong tide. The seabed due to the strong tide has been formed various bed-form (ripple, sand wave and sand dune) along direction and strength of the tide [2]. Unlike water-sediment interface with flat bottom, the sand wave and sand dune have a strong influence on acoustic propagation, reflection and scattering.In this paper, we present the effects of low-frequency sound waves caused by sand wave zone with the acoustic transmission loss data measured in shallow waters.1

In situ side-aspect target strength of Japanese anchovy (Engraulis japonicus) in northwestern Pacific Ocean

Acoustic side-aspect target strength (TS) of living Japanese anchovy (Engraulis japonicus) was measured at 120 kHz during in situ experiments. The data were collected by lowering and horizontally projecting the split-beam transducer into the anchovy school. For analysis and interpretation of the side-aspect TS data, acoustic theoretical model, based on the fish morphology, and dorsal-aspect TS data were used. Total length of the anchovy ranged from 6.6 to 12.8 cm (mean length 9.3 cm). The side-aspect TS distributed between -40 and -55 dB, has an obvious length dependency. The mean side-aspect TS of the anchovy was -47.8 dB, and the TS was about 2 dB higher than mean TS generated from dorsal-aspect measurements. With reference to maximum TS, the results of the side-aspect TS were distributed within the range of the theoretical and dorsal-aspect TS. Apparently these tendency indicates that side-aspect TS measured from the study is useful data. These in situ measurements of side-aspect TS can be applied to improve acoustic detection and estimates of the anchovy, and is necessary to measure with a various frequency and length for making enhance data.22Nkc

Influence of Wind- and Ship-generated Sound on Ocean Ambient Noise in Shallow Water

In this study, we measured the effects of ambient noise generated by wind and ship traffic on the ocean sounscape, with a focus on low-frequency bands (<1 kHz). The speed and direction of the wind were measured from a weather buoy operated by the Korea Institute of Ocean Science and Technology (KIOST). The hydrophone near the weather buoy was moored for one month to measure ambient noise. The measured ambient noise was analyzed using wind data from the weather buoy and automatic identification system (AIS) data, i.e., navigation information, of sailing vessels in the vicinity of the study area. From the analysis results, we confirmed that the measured ANL at 1 kHz increased as ships approached the hydrophone and fluctuated according to the speed and direction of the wind.ted by the Korea Institute of Ocean Science and Technology (KIOST). The hydrophone near the weather buoy was moored for one month to measure ambient noise. The measured ambient noise was analyzed using wind data from the weather buoy and automatic identification system (AIS) data, i.e., navigation information, of sailing vessels in the vicinity of the study area. From the analysis results, we confirmed that the measured ANL at 1 kHz increased as ships approached the hydrophone and fluctuated according to the speed and direction of the wind.1

Changes in Planktonic Communities and Environmental Factors between Open Versus Closed Artificial Marine Microcosms

To understand differences of environmental factors and planktonic communities in closed (CS) versus open (OS) enclosed experimental systems, we performed a study on a 100-L indoor-type artificial marine microcosm. For environmental factors, including water temperature, dissolved inorganic phosphorus, and dissolved silica, there were no significant differences between CS and OS; however, salinity was higher in CS than that of OS due to the evaporation effect. The concentration of dissolved oxygen and dissolved inorganic nitrogen was lower in CS than in OS. The abundance of phytoplankton was lower in CS than in OS. However, abundance of autotrophic nanoflagellates and heterotrophic bacteria varied inversely with that of phytoplankton abundances. In particular, the abundance of heterotrophic nanoflagellates and ciliates increased with bacterial growth after a time lag. Therefore, environmental factors and planktonic communities in CS gradually changed over time and characterized a different artificial ecosystem than in OS. 본 연구는 외부 해수가 계속적으로 유입되는 개방형 인공생태계와 해수의 유입이 없는 폐쇄형 인공생태계에서 미소생태계의 변화를 파악하고자 실험실 내에서 100 L 크기의 인공해양소형생태계 연구를 수행하였다. 수온은 폐쇄형 및 개방형 인공생태계에서 큰 차이가 없었다. 염분은 폐쇄형 생태계에서 수체의 증발에 따라 증가를 보였고 용존산소 및 용존무기질소 농도는 폐쇄형에서 감소하는 반면, 개방형에서는 초기농도와 큰 차이를 보이지 않았다. 용존무기인 및 용존규소는 두 시스템에서 차이가 없었다. 식물플랑크톤은 폐쇄형에서 감소를 하였던 반면, 개방형에서는 증가 양상을 보였으나 Autotrophic nanoflagellates는 식물플랑크톤 개체수의 변동과 반대되는 양상을 보였다. 타가영양세균은 폐쇄형에서 증가하는 양상을 보였고, 이와 함께 heterotrophic nanoflagellates 및 섬모충이 시간차를 두어 증가하는 양상을 보였다. 그러나, 개방형 인공생태계에서는 특이한 변화를 나타내지 않았다. 결론적으로, 폐쇄형 인공생태계와 개방형 인공생태계에서 미소생물상 및 환경요인들의 변화의 연구는 향후 연구자들이 인공생태계 연구에 있어서 기초자료로 활용할 수 있을 것으로 기대하며, 신뢰성 있는 인공생태계 연구를 수행할 수 있을 것으로 판단된다.33Nkciothe

APPARATUS AND METHOD FOR DETECTING MARINE RED TIDE

본 발명은 적조 탐지 신호를 디지털 센서 개념으로 구성하여 신호 전달 거리 증가에 따른 노이즈의 영향 을 줄이고 적조 생물의 주광성을 고려하여 적조 감지 센서의 수직 위치를 조절할 수 있는 해상의 적조 탐 지 시스템 및 그 방법에 관한 것이다. 본 발명의 해상의 적조 탐지 시스템은 해상의 적조를 탐지하여 이 에 상응하는 디지털 탐지 신호를 출력하도록 구성된 디지털 적조 탐지 센서, 및 상기 디지털 적조 탐지 센 서로부터 출력되는 디지털 탐지 신호를 확인하여 이 디지털 탐지 신호가 기설정된 레벨 이상이 되었을 때 적조 정보를 해상 기지국으로 전달하도록 구성된 적조 탐지 제어 장치를 포함한다

Integrated Operational Modeling of the Harmful Algal Blooms(HABs) Using R

Harmful algal blooms(HABs) are critical issues on the coastal ocean. Government agencies and ocean scientists are struggling to reduce the damage of coastal aquaculture by HABs. As a part of the effort, ocean scientists are conducting researches on how to cope with HABs and how to predict it before HABs occur. In this study, a model to predict the route and range of HABs was constructed to prevent damage caused by HABs. As with most ecological models, the major parts of the HABs model including physical, chemical, and biological factors are fundamental, but technical processes for efficient operation of the model are also important. The open source language, R, has a great advantage in performing comprehensivemodeling research because a wide range of libraries which are wellverified can be available. Whole modeling processes including data acquisition using API(Application Programming Interface) from government, localized physical model data input, rasterizing and computing spatial data and visualization of prediction results were integrated into the R and implemented with satisfaction. The integrated R code calculates the 72-hour forecast results everyday through the batch process.1

Preliminary observation along a hydrographic section in the Weddell Seaduring the 1996 field season (in English)

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Seasonal variation of the Sound scattering Layer (SSL) around Yellow Sea Bottom Cold Water (YABCW) in Korea region, 2011-2012

The Yellow Sea Bottom Cold Water (YSBCW), defined as having a salinity of 32.0&#8211;33.0 psu and a temperature < 10°C, has a major influence on the oceanic environment of the Yellow Sea and is one of the main water masses in this sea in summer. The presence of the YSBCW has important effects on zooplankton, nekton, and other biological organisms in the Yellow Sea. For understanding the sound scattering layer (SSL) in the YSBCW region, this study presents results obtained from acoustic measurements taken in the YSBCW region in Korea region, in spring and summer of 2011 and 2012. For each survey, 13&#8211;27 hours of 200 kHz acoustic data were continuously collected at a stationary station. The acoustic volume scattering strength data (Sv) were analyzed with temperature profile data. In spring 2011/2012, the SSL migrated from surface layer at night to near the bottom at day time, due to the entire water column was well mixed with cool water. Then the descending and ascending speeds of the SSL were 0.7 m min-1 and 0.6 m min-1, respectively. In summer seasons, the SSL migrated from below thermocline at night to near the bottom at day time, due to the water column was divided in to two layer along strong thermocline. The SSL started to descend at a speed of 1.3 m min-1. Very high speed in summer 2011 was due to changes of the water column after typhoon (called Muifa). In addition to water temperature, suspended materials may be some influence on vertical migration of the SSL. It is concluded that the SSL patterns at the YSBCW site may be greatly influenced by water column changes during spring and summer season.1

The effect on the propagation in shallow water with a mega-ripple

It is well known that acoustic propagation in shallow water is greatly influenced by an interaction of reflection, transmission, and scattering with the boundary condition. Especially, acoustic propagation of low frequency is depended on the structures of seabed and sub-botttom layer. In this study, acoustic propagations for low-frequency in shallow water were measured from field experiments under the condition of mega-ripple. The study area formed various mega-ripple caused by strong tidal current. Precisely bathymetry and sub-bottom structure were obtained from multi-beam and sparker system. In the experiments, acoustic source and receiver for propagation measurement were single bulb system and multiple self recording hydrophone system, respectively. From the measurement, we described characteristics of acoustic transmission for low frequency around the mega ripple regions.n the structures of seabed and sub-botttom layer. In this study, acoustic propagations for low-frequency in shallow water were measured from field experiments under the condition of mega-ripple. The study area formed various mega-ripple caused by strong tidal current. Precisely bathymetry and sub-bottom structure were obtained from multi-beam and sparker system. In the experiments, acoustic source and receiver for propagation measurement were single bulb system and multiple self recording hydrophone system, respectively. From the measurement, we described characteristics of acoustic transmission for low frequency around the mega ripple regions.1