Determining Watershed Management Efficacy in West Maui: Belt transect surveys of coral demography (adult and juvenile corals) from 2014 to 2015

The focus of the Wahikuli-Honokowai Watershed Management Plan is the land use practices and alterations affected in the agricultural and urban districts that have upset the natural drainage patterns and ecohydrologic balance and services the watersheds provide. As the approach to reducing the effects of land-based sources of pollution, the Wahikuli-Honokowai Watershed Management Plan identifies nine priority projects to reduce, capture, and remediate the impacts of non-point source pollutants through the implementation of management practices in priority areas. The Watershed Management Plan also includes recommendations for strategic, long-term trend monitoring of the health of the coral reef ecosystem, which provides information that can be correlated to the implementation of solutions to reduce land-based non-point source pollutants.

Kahekili Beach Park reef and the coastal areas to the north are considered high priority. Corals in this region have been severely impacted by land-based pollutants, causing coral dieback and reducing coral cover. To fill in the gap, a baseline assessment for coral demographic metrics (described here) along with benthic cover has been conducted at the mouths of the Mahinahina, Honokowai, and Wahikuli, Kahana, Honokeana, Honokohua, and Honolua stream drainages in West Maui, Hawaii, to track and evaluate the efficacy of implemented management practices. The installation of permanent survey transects will provide long-term time series to quantify changes in the reef benthic community. Sediment flux, and turbidity data are also collected at the Mahinahina, Honokowai, and Wahikuli, dranages (described separately).

The data described here were collected via belt transect surveys of coral demography (adult and juvenile corals) by the NOAA Coral Reef Ecosystem Program (CREP) according to protocols established by the NOAA National Coral Reef Monitoring Program (NCRMP). In 2014 data were collected at the Mahinahina, Honokowai, and Wahikuli watersheds; in 2015 data were collected at the Kahana, Honokeana, Honokohua, and Honolua watersheds. These data include:
1) an assessment of coral colony density and size-class distribution for the selected monitoring sites;
2) an assessment of coral recruitment at the monitoring sites; and
3) an evaluation of coral colony mortality and evidence of sediment stress.

Data is available for surveys conducted in 2014 and 2015. These data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive, accession #0137092.

Additionally, line-point intercept and photoquadrat surveys of the benthos were conducted (described separately), and turbidity sensors, sediment traps, and sediment pods were deployed by project partners to provide information on sediment loads, sediment accumulation rates, and sediment composition. As watershed management projects are implemented, changes in sediment and nutrient loading and the resulting impacts on the reefs can be monitored over time.