The Dongsha Management Station of the Marine National Park Headquarters (hereinafter referred to as the Headquarters), in collaboration with Professor Shih Hsi-te of the Department of Life Sciences at National Chung Hsing University, conducted a week-long survey of crab fauna on Dongsha Island. A total of 19 crab and hermit crab species were recorded for the first time in Dongsha, adding significant new findings to the biodiversity of the terrestrial and intertidal zones of Dongsha Atoll National Park.
　　The Headquarters noted that previous surveys in Dongsha Atoll National Park had focused primarily on coral reef marine environments. Only 16 species of crabs in 7 families had been recorded from terrestrial and intertidal areas. However, within just one week of investigation, this survey documented 34 crustacean species across 12 families, including species such as the fiddler crab Uca jocelynae (family Ocypodidae) and the land hermit crab Coenobita rugosus (family Coenobitidae). Among these, 19 species from 11 families—including Ocypodidae, Eriphiidae, and Coenobitidae—were new records for Dongsha, demonstrating the remarkably high crab biodiversity within Dongsha Atoll National Park.
　　To further explore crab diversity in Dongsha’s terrestrial and intertidal zones, staff from the Dongsha Management Station and Professor Shih’s research team conducted comprehensive surveys from September 1 to 8 across various habitats, including sandy beaches, intertidal zones, the island lagoon, terrestrial environments, and coastal forests. The findings will support conservation planning for crab species within the park. The lagoon area of Dongsha Island was found to be particularly rich in crabs, especially fiddler crabs, which feed on organic detritus. The organic-rich shores of the lagoon provide essential habitat for these species. Additionally, the mud crab Scylla serrata (commonly known as the red mud crab) is rarely observed in the surrounding offshore waters but is concentrated within the lagoon area, indicating that the lagoon serves as its primary habitat.
    　The survey also unexpectedly revealed that driftwood deposited on sandy beaches serves as an important habitat for crabs. Many newly recorded species were found exclusively beneath driftwood, including species from genera such as Metopograpsus and Perisesarma. These pieces of driftwood, carried across the ocean and stranded on beaches, have become vital microhabitats. Maintaining habitat diversity along coastlines is therefore crucial for biodiversity conservation.
    　The Headquarters stated that since the establishment of Dongsha Atoll National Park in 2007, efforts have extended beyond coral reef ecosystem surveys to include resource investigations of various organisms. However, given the park’s vast area and rich biodiversity, continued research and monitoring remain necessary. The 19 newly recorded crab species documented in this survey not only open a new chapter in crab diversity research for Dongsha Atoll National Park but also enhance understanding of crab resources and biodiversity, providing valuable direction for future conservation efforts within the park.   Written by: Contract Researcher Huang Shih-pin.

Figure 1: Fiddler crab active along the lagoon shore of Dongsha Island	Figure 2: Driftwood on Dongsha beaches provides excellent habitat for many crab species
Figure 3: Short paddle crab found only in the lagoon area of Dongsha	Figure 4: The brightly colored fiddler crab is the most dominant fiddler crab species in Dongsha