War-in-the-Pacific National Historical Park Marine biological survey

Amesbury, Steven; Ginsburg, David; Rongo, Teina; Kirkendale, Lisa; Starmer, John

Only a limited amount of biological survey work had previously been done in the park's marine areas. This consisted largely of a single biological survey by University of Guam investigators within a portion of what is now the Agat unit in the mid-1970's. Park concern for impacts from local fishing activities, increasing recreational use, and increasing sedimentation and pollution from upland runoff within coastal developed areas made a baseline survey and documentation of reef conditions a high priority. In addition, fishery harvest data collected by the Guam government's Coastal Management Program has recently shown that fishing hours are steadily increasing while estimated total harvest is declining annually. The park has also been negotiating with the Government of Guam for complete NPS management authority over the submerged natural resources within the park units, and an understanding of the current condition and impacts to these resources is necessary for successful negotiation. To address these concerns, WRD has funded a study over the past two years to provide a baseline inventory and assessment of the marine resources within the two submerged units of the park. The study was completed this year. Underwater field survey work was contracted to Dr. Steve Amesbury of the University of Guam, Marine Laboratory. Dr. Amesbury's survey was designed to provide a qualitative and quantitative assessment of fish, coral, and marine plants throughout the marine habitats of the park. A less complete assessment of marine macroinvertebrates was also included. Four fish transects surveyed in 1974 were resurveyed using the same methods to determine whether any significant changes in the fish communities had occurred over the intervening years. In addition to Dr. Amesbury's work, digital orthophoto imagery in stereo paired, color infrared and panchromatic photography for WAPA's reef areas was obtained. The Pacific Island Support Office is processing this data into GIS layers for the park. The results of this study have provided a baseline documentation of diversity, abundance, and distribution of marine plants, coral and fish within the park marine units. In addition, up to 191 species of macroinvertebrates were documented to occur within the park marine waters (although many additional species are likely to be found with further macroinvertebrate studies). A comparison of the current study results to those of the 1974-77 surveys showed some differences in marine plant abundance and a slightly lower overall fish species diversity but higher fish abundance. Algal density within some areas of the reef appears to have changed, which may be due to nutrient inputs and water quality changes. However, on the whole, comparison of the 1974 and 1999 data for the Agat unit does not suggest there have been major changes in the fish, marine plant, or coral communities over the intervening years and that the park's marine resources remain in a relatively healthy condition.