Kona IEA Science Symposium Highlights Status and Trends in Kona's Marine Ecosystem

The Symposium on Kona's Marine Ecosystem: Status and Trends was held September 4 - 5 in Kailua-Kona. The event featured 44 presentations covering topics ranging from satellite tools, observational and GIS products, distributions and spatial patterns of marine mammals, mesophotic reefs, aquaculture, and spatial and temporal patterns in coral and nearshore fish communities. There were also presentations on community-based efforts to quantify local fishing effort and assess fish spawning with a view to producing educational tools to promote best-fishing practices. Over 180 individuals participated and represented a broad spectrum of federal and state agencies, non-governmental organizations and the local community.

Wave power (kW/m) at three sites located north to south along West Hawaiʻi: Puako (black line), Kailua-Kona (magenta line) and 
        Milolii (green line). Horizontal bars are the corresponding upper climatological limits of wave power for each geographic area. Wave 
        forcing increases towards the southern end of West Hawaiʻi, as evidenced in both the higher upper climatological limits and 
        greater magnitude of peak wave events in that region.
Wave power (kW/m) at three sites located north to south along West Hawaiʻi: Puako (black line), Kailua-Kona (magenta line) and Milolii (green line). Horizontal bars are the corresponding upper climatological limits of wave power for each geographic area. Wave forcing increases towards the southern end of West Hawaiʻi, as evidenced in both the higher upper climatological limits and greater magnitude of peak wave events in that region.

Some major research findings presented in the symposium include:

1: Large spatial differences in climatological wave forcing are apparent along West Hawaiʻi, with more than a doubling in upper climatological limits observed from Puako to Milolii (see figure). Wave forcing is an important driver of coral reef benthic community structure and can serve as an indicator for understanding temporal changes in reef ecosystems along West Hawaiʻi.

2: Since 1978, the total abundance of reef-associated fish has declined by 52% (range of 43 - 61% across all habitats) in the South Kohala region. Similar changes in the benthic community have also been documented, including a 28% decline (21 - 35%) in overall coral cover.

3: Sedimentation severely limits coral recruitment and is potentially a major driver of coral community changes observed along the Kohala coastline. Sediments in the water column near Pelekane Bay were driven by both re-suspension of sediments by waves and wind and new input generated by precipitation and subsequent land runoff. The largest sedimentation event over a 12-month time period was associated with the 2011 Tohoku Tsunami in Japan, which increased suspended sediment 7 fold compared to all other events observed during the study period.

4: Simulations of larval retention across the main Hawaiian Islands show that West Hawaiʻi potentially retains approximately 80% of larval propagules, nearly twice the proportion of any other location.