台灣北部及東南部硬底質海岸潮間帶寄居蟹群集分析

Intertidal hermit crab assemblages on hard substrates along northern and southeastern coasts of Taiwan

硬底質海岸地形提供各種造礁生物生長，例如珊瑚、殼狀珊瑚藻與管蟲等，形成生物礁，進而提供多樣的海岸生物共棲。本研究於2016-2018年期間針對台灣北部及東南部硬底質海岸，包括西北海岸桃園觀音藻礁、北海岸及東北海岸的宜蘭岩石地形，以及台東沿岸珊瑚礁。設置88個11㎡樣框，進行21種寄居蟹群集型的多變量統計分析，參考樣區間及物種間之相關趨勢所繪分布序列圖，以及群團分析之相似性所繪樹形圖等，可將寄居蟹分成三個群集群，分別為庫卡寄居蟹群集型、綠色細螯寄居蟹群集型以及線斑真寄居蟹群集型。藉由這三個群集型，進一步識別出各寄居蟹群集型物種組成之代表性物種及族群量，以及描述棲地特性和列舉各型之共棲優勢種或特徵種。分析結果顯示北部海岸寄居蟹於退潮時段會群聚，西北海岸之庫卡寄居蟹群集型，沿著桃園的觀音大潭藻礁低潮線，庫卡寄居蟹平均1㎡樣區出現個體數達136.6隻，單一樣區個體數可有352隻的紀錄。北海岸之綠色細螯寄居蟹群集型，綠色細螯寄居蟹平均1㎡樣區出現個體數67.3隻，單一樣區個體數可有365隻的紀錄，物種多樣性指數以金山為最高為0.544，綠色細螯寄居蟹是少數跨台灣西北海岸到東南海岸都出現的種，只是北海岸的數量最多，本種在各樣區記錄隻數合計達2018隻。東北海岸及東海岸寄居蟹雖無明顯之優勢種，但可歸為線斑真寄居蟹群集型。此型單位面積的種類較多，但數量少，台東的基翬漁港，物種多樣性指數達0.764。

Hard substrates in coastal terrain can provide reefs to accommodate diverse coastal biocompatibility for a variety of organisms, such as reef-building corals, crustose coralline algae and tube worms. Intertidal hermit crab assemblages on hard substrates were investigated along northern and southeastern coasts of Taiwan from 2016 to 2018, including the Taoyuan algae reefs off the northwest coast, the north coast, the Yilan rocky substrate along the northeast coast and the coral reefs along the Taitung coast. The hermit crabs were sampled in 88 11㎡sampling plots. Twenty-one hermit crab species were found. According to the results of multivariate analysis, ordination of correlation trend between the species, similarity of the cluster analysis and classification of the hermit crab group, a total of three assemblage types were identified: Pagurus kulkarnii assemblage type, Clibanarius virescens assemblage type and Dardanus guttatus assemblage type. The species composition, habitat types and sympatric species of dominant species or characteristic species in habitat niche of each assemblage type were described. The survey found that the hermit crabs gathered at low tide during the low tide period along the north coast. Pagurus kulkarnii, a monodominant community off the northwest coast of Taiwan, showed a maximum of 352 individuals in a sampling plot, with an average number of 136.6 individuals appearing in the 1㎡ plots at low tide lines of Baosheng and Datan algal reefs in Guanyin, Taoyuan. The north coast was dominated by Clibanarius virescens. The average number of individuals in the 1㎡ plots was 67.3, and the maximum number of individuals in a single plot was 365. The species diversity index was 0.544 in Jinshan of the north coast. Clibanarius virescens is widely distributed across the northwest coast to the southeast coast of Taiwan. Its number is the highest in the north coast, and a total of 2,018 individuals were recorded in the plots. There were no obvious dominant species in the northeast and east coasts. There were many species of hermit crabs, but only in few numbers. The species diversity index was 0.764 in Kihaw Harbor, Taitung.