Erik JohnsonTCBES Masters program

University of Hawaii at Hilo

Surface water metabolism potential of groundwater-fed near shore waters on the leeward coast

of the Island of Hawaii

Groundwater discharge

• Major source of freshwater to Leeward Hawaii

• Groundwater introduces nutrients– Nitrogen and phosphorus

• Nutrients stimulate productivity– algal blooms

Surface Water Metabolism (MET)

• MET= gross primary production (GPP) -respiration (RESP)

• GPP > RESP – Autotrophic– CO2 sink

• GPP < RESP– Heterotrophic– CO2 source

Hypotheses

• pMET higher within groundwater plumes– Groundwater introduces nutrients

• pMET higher in wet seasons– Higher nutrient concentrations

Study sites

• Kiholo Bay– Undeveloped

• Kaloko-Honokohau– Developed

• Well documented groundwater inputs

Sample collection• 6 stations

– 3 in-plume, 3 out-plume– Monthly for 1 year

Salinity at Kaloko-Honokohau

Kaloko-Honokohau, Feb 12, 2011

Kaloko-Honokohau, Feb 2011

GPP RESP pMET-5

-2.5

0

2.5

5

7.5

10

In plume

Out plume

mm

ol O

2 m

-3 d

-1

Mahalo!Acknowledgments:

Tracy WiegnerJason Adolf

Matthew ChurchJudy Walker

Rebecca MostEPSCOR III

NSFPRISM