The annual reproductive cycle of two species, Upogebia major (de Haan 1841) and Austinogebia wuhsienweni (Yu 1931), of the female mud shrimp from the west coast of Korea was investigated using histology. The collected samples were divided into adult and juvenile groups to understand the mature period of age class based on the carapace length (CL). Juvenile Upogebia (CL<25 mm) were mostly inactive gonad with early (62%-100%) and late (10%-38%) development stages during the year, whereas the adult shrimp showed a seasonal pattern of gonad maturation (CL≥25 mm). The early and late developmental stages of oocytes were observed in adult Upogebia from November to March and mature eggs appeared from April to October. In adult Ausitnogebia (CL≥15 mm), fully grown oocytes were consistently observed during the study period, in which the ripe stage was found between January and June. On the other hand, most juvenile Austinogebia (CL<15 mm) maintained an immature state in the gonad. Both species of the mud shrimp reproduced from ovigerous females in the adult population and their egg-bearing period was distinguished from January to April for U. major and from July to September for A. wuhsienweni.

In this paper, a water-based green polymer mud is synthesized by simple compounding method. Effects of different kinds of tackifiers, their molecular weight on the viscosity of polymer mud and the effects of different fluid loss additives on mud fluid loss are studied. The results show that when polystyrene and anionic polyacrylamide with molecular weight of 8 ~ 10 million are used as the main thickening ingredient, polymer mud with high viscosity and high stability can be obtained. When the prepared polymer mud is formulated as NPAM: PEO: Hydroxypropyl cellulose(HPC) :Water = 42:10:10:100000 (unit: kg), the viscosity can reach 20.6 s, the filtration loss in 7.5 min is 24 mL, and the sand content is only 0.1%. Compared with traditional bentonite mud, the green environment-friendly polymer mud has the advantages of small amount of waste, low environmental pollution, and low pulping cost, and can meet the construction needs for most topography and geomorphology drilling engineering

Although mud shrimp (Upogebia Major) provides benefits on the tidal flat ecosystem, it is causing the mass mortality of Manila clam (Tapes philippinarum) and large economic loss to the aquaculture farmer due to spreading in the entire coastal clam farm area of the West Sea of Korea. In this study, a mud shrimp blocking box for cultivating clam was tested to prevent the mud shrimp from invading the habitat of the clam. To determine the effect of the blocking box, the growth characteristics of the clams under various culture conditions were investigated. The shell length, total weight, condition index, the presence of mud shrimp in the box, and the soil decay in the box were examined according to whether the clams were raised in the box or in natural state, whether the box is covered with a net or not and the gap size of the box. As a result, no significant differences in shell length, total weight, and condition index were found between the clam grown in the box and the natural state (P>0.05) without any evidence of invading of mud shrimp to the box. In addition, the soil inside the box was in good condition, not decayed. Therefore, using the mud shrimp blocking box, mud shrimp can be prevented from propagating to the habitat of the clam, thereby contributing to the normal production of the clam and thus to restoring the clam farming.

A commercial CFD code is used to caculate the 3-D viscous flow field within the centrifugal pump impeller. Design conditions are changed by pump inlet diameter(203.2㎜) and pump outlet diameter(152.4㎜). Numerical calculation was performed by changing flow rate from 7 to 12m 3 /min. Working fluids are clean water and muddy water. The viscosity of muddy water is measured by the unsteady capillary of the viscometer. The pump performance is predicted well through the computer simulation. The results are summarized as follows: the pump characteristics of the total pressure, efficiency and shaft power with high viscosity fluids by muddy water was different from those clean water. When the viscosity of the applied fluid increased, the total pressure, and efficiency more decreased than those of clean water. The decreasing gradients of the total pressure and the efficiency were larger than water due to the increased disk friction losses at the duty operation point. The shaft power of clean water and muddy water increased. This study shows that the calculated results agree well with the analysis results of design condition.

본 연구에서는 쏙류의 고밀도 서식 때문에 2008년 이후 피해가 급격히 증가하고 있는 한국 서해안 갯벌의 패류양식장에서 착저 초기에 쏙과 가시이마쏙의 초기 성장, 서식 깊이, 상대성장 특성을 구명하여 물리적 제거 또는 포획에 관한 기초적 생태자료를 확보하고자 하였다. 5월 초순에 갯벌에 착저한 어린 쏙은 8월 이후에 두흉갑장이 10 mm 이상으로 성장하였고, 갯벌에 착저 후 1년 경과 시 두 흉갑장 (CL)과 전장 (TL)이 각각 14.21 mm, 42.28 mm까지 성장하였으며, 주 성장 시기는 4~10월이었다. 당년산 어린 쏙의 서식 깊이는 성장과 더불어 착저 후 약 6개월 경과 시까지 빠르게 증가하였다 (7월 5 cm, 9월 12.5 cm, 11월 28 cm). 어미 쏙 (평균 두흉갑장 28.50 mm)의 연중 서식 깊이는 10~93 cm이었다. 쏙의 두흉갑장 (CL)-전장 (TL), 두흉갑장-습전중량 (TWW) 간 상대성장을 분석한 결과, 두흉갑장 26~35 mm 크기에서는 쏙의 습중량이 천수만 입구의 주교 갯벌에 비해 천수만 내측의 사호리 갯벌에서 1.2~4 g 더 무거운 것으로 예측되었다. 본 연구에서 밝혀진 당년산 어린 쏙의 착저 후 초기 성장과 서식 깊이의 증가 특성으로 볼 때, 어린 쏙이 바지락 양식장 등에 정착하여 피해를 주는 것을 줄이기 위해서는 5~6월경에 쏙의 착저 여부를 주의해서 관찰해야 하며, 다량의 쏙 서식이 확인되면 갯벌 속에 30 cm 보다 얕게 굴을 파고 서식하는 8월부터 12월 사이에 어린 쏙을 제거하기 위한 다양한 노력을 기울일 필요가 있을 것으로 판단된다. 또한 보령지역 어미 쏙의 시기별 평균 서식 깊이 면에서 볼 때 1차 제거 적기는 쏙들이 표층에 가장 가까워지는 3월부터 5월 초순, 2차 적기는 10월 중순부터 12월 초순으로 판단된다. 쏙은 갯벌양식장에서 공간점유와 먹이 경쟁 등 인간의 경제활동에는 부정적인 영향을 주지만, engineering species로서 갯벌에 수많은 구멍을 깊게 뚫어줌으로써 다양한 생태계적 순기능도 수행하고 있으므로 친환경적이며 합리적인 대응 방안을 지속적으로 모색할 필요성이 있을 것으로 판단된다.

흑산 니질대에서 채취한 코어 퇴적물 HMB-103으로부터 규조를 분석하여 3개의 규조 군집대를 설정하였고, 산 출된 한랭수종과 온난수종, 염분도에 의해서 고환경을 해석하였다. 규조는 총 41속 76종이 감정되었으며 규조 개체수 농도는 0.1-15.4×104 g−1 의 범위에 해당된다. 연구 결과, 약 45,000 yr B.P.경까지의 규조 군집대 I에서는 한랭수종의 산 출이 많은 것으로 보아 한국연안류의 영향을 주로 받았으며, 14,000부터 11,646 yr B.P경까지의 규조 군집대 II는 규조 의 산출이 거의 없는 추운 시기(Younger Dryas)로 생각된다. 그러나, 11,646 yr B.P부터 홀로세까지의 규조 군집대 III 시기에는 해수면이 상승하면서 황해 난류의 영향을 더 많이 받았다.

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 δ13C values of the diets indicated wide ranges (- 26.5‰ to - 8.4‰) while benthos showed a small range of δ13C 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, δ15N values of the diet candidates (5.7±1.0‰) were lighter in comparison to those of the benthos (11.8±1.9‰). Based on the δ13C and δ15N 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.

PFOS (perfluorooctane sulfonate) is one of the perflourinated organic compound, which persist as a residual compound in the coastal environments. Intertidal mud crab Macrophthalmus japonicus mainly inhabits in coastal and bay ecosystems in Indo-Pacific region including Korea and reflects to environmental changes. In the present study, M. japonicus were exposed to different concentrations of PFOS and various ecotoxicological end-points such as survival rate, elimination of appendages, changes of the crust and internal organ color changes were investigated. Interestingly, the PFOS exposure showed concentration-dependent decrease of survival rate. High PFOS exposure (30 μg L-1) showed a low survival rate of 24% at 168 hours. Further, in comparison with the controls, the rate of elimination of appendages was also considerably increased in a time dependent manner upon PFOS exposure. Notably, with progression of time, an increased exposure to PFOS, test species showed whitening effect in a concentration-dependent manner, whereas the crab crust color was unchanged in the control. In addition, change in internal organs color and their visibility (clarity) observed in PFOS exposed crabs compared to control. Taken together, we suggest, eco-toxicology end-points of M. japonicus exposed to PFOS gave important biological information which could be useful to identify toxic contamination in the marine benthic environments.

대부분 니질 퇴적물로 구성된 황해 남동부 흑산니질대 퇴적물의 기원지를 밝히기 위해 퇴적물 시료에 대해 주성분 원소와 희토류 원소(REE)를 분석하였다. 표층 퇴적물 시료는 흑산니질대 내 51지점에서 피스톤식과 박스형 시료 채취기로 획득하였다. 흑산니질대의 표층퇴적물은 니 퇴적물이 우세하게 나타나며, 평균입도는 5-6φ이다. 공간적으로 북쪽지역은 실트함량이 높고, 남쪽지역으로 갈수록 점토함량이 증가한다. 흥미롭게도 주성분 원소와 희토류 원소 함량 특성은 퇴적물 기원 해석에 있어 다른 결과를 가져왔다. Fe/Al과 Mg/Al 함량 비, Al2O3와 MgO 함량 비, Al2O3와 K2O를 각각 도시한 결과, 흑산니질대 퇴적물은 한국 기원의 퇴적물이 우세한 것으로 나타났다. 하지만 희토류 원소의 특성은 중국 기원의 퇴적물이 우세함을 반영한다. 이러한 기원 불일치는 각 원소의 함량 조절요인이 다르기 때문이다. 주성분 원소는 입도와 높은 상관관계를 고려할 때 입도에 따라 그 함량이 영향을 받는 것으로 해석된다. 반면에 희토류 원소는 입도와는 상관관계가 낮으며, 중광물 함량에 의해 조절되는 것으로 사료된다. 이와 같이, 각기 다른 추적자에 따른 기원의 불일치를 해결하기 위해 추가적인 연구가 필요하다.

호남권 해안은 대한민국의 전체해안선 중에서도 갯벌의 면적이 가장 크며, 세계적으로 인정받는 청정 갯벌지역을 보유하고 있다. 본 연구에서는 갯벌을 대상으로 하고 있는 관광 자원과 활용 방법을 알아보고자 한다