Secondary production of a mudflat amphipod, Monocorophium acherusicum (Amphipoda, Corophiidae) inhabiting seagrass (Zostera marina L.) beds in southern Korea

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Population dynamics and production of Pontogeneia rostrata (Crustacea: Amphipoda) in a sandy shore

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Seasonal Variation and Feeding Habits of Amphipods Inhabiting Zostera marina Beds in Gwangyang Bay, Korea

On the basis of monthly samples, we investigated the seasonal variation and feeding habits of amphipods inhabiting Zostera marina beds in Gwangyang Bay. Dominant species (>1% of the total number of amphipods) consist of 5 gammarids (Gammaropsis japonicus, Jassa slatteryi, Pontogenia rostrata, Atylus collingi and Ceinina japonica) and 1 caprellid (Caprella tsugarensis). Mean densities of amphipods varied from the highest of 63,148 ind. m-2 in May to the lowest of 1,247 ind. m-2 in September. G. japonicus and J. slatteryi dominated in summer whereas C. japonica in autumn and winter. C. japonica was found to be a carnivorous feeder consuming mainly harpacticoid copepods and unidentified crustaceans, whereas G. japonicus, J. slatteryi, and C. tsugarensis consumed both phytoplankton and detritus. Seasonal densities of amphipods were significantly related with the shoot standing crop of the eelgrass and its epiphyte. Also densities of amphipods displayed significant difference in related with the shoot density of the eelgrass among sampling stations. These results suggest that the biological interactions between the eelgrass and amphipods as well as between the carnivorous and the herbivorous amphipods may be important in the seasonal variation of amphipods inhabiting Zostera marina beds.22Nkc

Intraspecific Zonation of the Benthic Amphipod Pontogeneia rostrata in Relation to Diel and Tidal Cycles

돌산도 모래해안 쇄파대에서 1993년 1월 소조와 대조 때 1조석주기 동안 채집한 저서성 단각류 시료를 가지고, 주야와 조석주기에 따른 Pontogeneia rostrata의 종내 대상분포를 조사했다. P. rostrata의 밀도는 대조보다는 소조때 높았다. 개체군을 성체 암·수컷과 미성체로 나누어 보면. 미성체와 수컷의 밀도가 각각 소조와 대조때 가장 높았다. 체장빈도 자료에 따르면. 겨울철에 미성체의 사망이 큰 것 같다. 야간 표층에서 소조때는 미성체 그리고 대조때는 성체 암·수컷이 유의하게 많았다. 이것은 미성체와 성체의 수직이동 양상이 조석에 따라 다르게 나타난 것으로 여겨진다. 대조 밀물때 평균해수면 (MSL) 위에 나타난 P. rostrata의 90% 이상이 성체였다. MSL 위에서 암컷/수컷의 비율이 감소했고, 암컷의 체장은 변동이 없었지만 수컷의 체장은 증가했다. 이것은 몸이 큰 수컷의 활발한 이동습성을 가리킨다. 이런 행동은 큰 수컷의 분포역 확장으로 이어지고, 교미와 섭식경쟁에 있어 큰 수컷에게 유리할 것으로 여겨진다. 성체가 대조 야간에 MSL 위 100㎝에서 채집되기도 하지만, 나머지 기간에 P. rostrata개체군은 대부분 MSL 아래에 머물렀다. 분포중심은 MSL아래 50㎝에서 200㎝ 사이였다. Using a sledge net, the benthic amphipods were taken over one cycle of the neap and spring tides in January 1993 at the sandy shore surf zone of Dolsando, southern Korea. From these samples, we investigated the diel and tidal effects en the intraspecific zonation of Pontogeneia rostrata. The density of P. rostrata was higher during neap tide than spring. Of three categories (adult males and females and juvenile), juveniles and males attained to its highest density during neap and spring tides, respectively. Length-significant that juveniles were significantly more abundant during neap tide than spring, whereas both adult males and females were more abundant during spring tide than neap. This suggests that the vertical migration patterns of juveniles and adults vary with the type of tides. During flood of spring tide, more than 90% of population collected at the area abode the mean sea bevel (MSL) were adults. With a decrease of female/male ratio, size of males increased there but that of female did not change, indicating an active migration of large males. This behavior can provide an extension of distribution area for large males, and also give a competitive advantage to large male against small one for mate and feeding. Although adult P. rostrata was collected at 100 ㎝ above MSL at night during spring tide, a major portion of population as usually present on the shore below MSL The renter of zonation was restricted from 50 ㎝ to 250 ㎝ below MSL22Nothe

Three new species of deep-sea genus Collettea Lang, 1973 (Tanaidacea, Tanaidamorpha, Colletteidae) in the eastern central Pacific

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Effect of water masses in spatio-temporal variation of oncaeids and corycaeids (Copepoda, Cyclopoida) in northern East China Sea during spring

We investigated a spatio-temporal distribution and species composition of small planktonic cyclopoid copepods, oncaeids and corycaeids, in relation to hydrographic characteristics in the northeastern East China Sea during spring (April) of 2004, 2008, 2010, and 2011. Results of the present study suggest that the distribution and composition of oncaeid species and corycaeid species except for D. affinis are influenced by intrusion of Tsushima Warm Water in the northeastern East China Sea, as well as closely related to the continuous variation of surface water temperature front around Jeju Island.1

Life history and reproduction of Jassa slatteryi (Amphipoda, Ischyroceridae) inhabiting seagrass (Zostera marina L.) beds in southern Korea

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Population ecology and trophic diversity in amphipods within a temperate eelgrass ecossytem

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Two new species of the deep-sea Neotanais Beddard, 1886 (Crustacea, Tanaidacea) from the North East Pacific

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Molecular phylogeny and divergence times of the superfamily Centropagoidea (Calanoida: Copepoda)

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