Monitoring of the freshwater amphidromous populations of the 'Ohe'o Gulch Stream system and Pua'alu'u Stream, Haleakala National Park

Hodges, Marc H.

Monitoring of the freshwater amphidromous populations of the 'Ohe'o Gulch Stream system and Pua'alu'u Stream, Haleakala National Park

Files

093.pdf (1.76 MB)

Date

1994-12

Authors

Hodges, Marc H.

Publisher

Cooperative National Park Resources Studies Unit, University of Hawaii at Manoa, Department of Botany

Abstract

Conservation and management of Hawai'i's native freshwater-amphidromous fishes, crustaceans, and gastropods is hindered by a lack of biological information. A one year project was begun at 'Ohe'o Gulch, Haleakala National Park in November, 1992 to develop population survey methodologies for application at 'Ohe'o and other streams, to establish a baseline of population information at 'Ohe'o, and to gather population data which could be compared to populations elsewhere. Direct observation quadrat methods were used to survey the populations of 'o'opu (Lentipes concolor, Sicyopterous stimpsoni, and Awaous guamensis), 'opae kuahiwi (Atya bisulcata), and hihiwai (Neritina granosa). Trapping was used to survey the alien prawn Macrobrachiurn lar. During the project the 'o'opu and 'opae populations were surveyed twice each. Hihiwai and M. lar were surveyed three and four times each respectively. Habitat quality appeared poor overall, but good in some upper segments of the stream system. The method developed for 'o'opu provided consistent results between observers and through time. Methods for the other species also provided good results. In the cases of 'o'opu and 'opae, numerical resampling of survey data demonstrated that statistical power to detect temporal changes in overall density is likely to be enhanced by using fewer quadrats per station and a greater number of stations in subsequent surveys. The overall size frequencies and the within stream distribution of average sizes of 'o'opu, 'opae, and M. lar were fairly stable. The within-stream species distribution of 'o'opu conformed to expectations and was also stable. In comparison with other streams in pristine areas of Hawai'i, 'o'opu and 'opae abundance was generally low. However, 'o'opu 'alamo'o were locally abundant and individual 'alamo'o were very large in some areas. Hihiwai were almost non-existent and appear to have declined in abundance since a prior survey two decades ago. M. lar were abundant and exhibited symptoms of 'black-spotted' disease. Other demographic characteristics of these species were analyzed. The causes of the observed low native faunal abundance in 'Ohe'o are unknown. Limited surveys were also carried out in next-door Pua'alu'u Stream. Within-stream species distribution differed between lower 'Ohe'o and the lower reach of Pua'alu'u. Such difference may be attributed to differing hydrology and geomorphology. Population monitoring in 'Ohe'o should continue and include monitoring of reproduction and recruitment via larval trapping at the terminus. Such monitoring might be conducted in conjunction with an M. lar control program.

Description

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Keywords

Animal populations -- Hawaii -- Maui., Freshwater animals -- Hawaii -- Maui., Haleakala National Park (Hawaii), Stream animals -- Hawaii -- Maui.

Citation

Hodges MH. 1994. Monitoring of the freshwater amphidromous populations of the 'Ohe'o Gulch Stream system and Pua'alu'u Stream, Haleakala National Park. Honolulu (HI): Cooperative National Park Resources Studies Unit, University of Hawaii at Manoa, Department of Botany. PCSU Technical Report, 93.

URI

http://hdl.handle.net/10125/7255

Collections

The PCSU and HPI-CESU Technical Reports 1974 - current

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