Past – Page 2 – Hawaii Sea Grant

09 Mar: The role of sponges in nitrogen cycling in Kāneʻohe Bay, Oʻahu

PI: Brian Popp
This study focused on quantifying respiration, pumping rates, and chemical reactions of an invasive sponge, Mycale grandis, to understand the species’ impacts on nitrogen cycling in the coastal environment of Kāne‘ohe Bay, whether adding or subtracting usable nitrogen from the system. Researchers found that the M. grandis sponge can pump 83 times its own volume of water per day, giving its associated microbial communities abundant opportunity to perform nitrification, converting ammonia to forms of nitrogen oxides unusable to algae. The rapid nitrogen transformations with the high pumping rates of these sponges means this invasive species may play a significant role in nitrogen concentrations in the bay.

By Rachel Lentz Coastal and Climate Science COE project Past Research Project Sustainable Coastal Tourism

09 Mar: Source tracking coastal groundwater and runoff contamination with microbial genomics and dissolved organic fluorometry

PI: Craig Nelson
This project focused on using new techniques of microbial genomics and fluorescent characterization of organic matter to track sources of groundwater contamination in several important Hawaiian watersheds, in order to provide tools to protect streams, groundwater, and coastal ecosystems. The high density of cesspools in Hawaiʻi is a potentially significant source of contamination to streams and coral reefs, but it is currently prohibitive to identify contamination sources. For this project, hundreds of water samples from Oʻahu, Maui, and Hawaiʻi have been collected and are being characterized to develop microbial source tracking and better testing techniques.

By Rachel Lentz Coastal and Climate Science COE project Past Research Project

09 Mar: Do seawalls lower property values?

PI: John Lynham
This work examined the economic consequences of a strategy commonly used in years past of building sea walls to protect property threatened by increased coastal erosion. Based on a technique previously used successfully by the authors in San Diego, CA, the researchers examined property sales on Oʻahu for the last 30 years and combined this with locations of seawalls built over those years. They found that while properties with coastal armoring maintain their value, there is evidence that neighboring properties show a decrease in value with time.

By Rachel Lentz Coastal and Climate Science COE project Past Research Project Sustainable Coastal Tourism

09 Mar: Rapid Response: Application of a qPCR-based test for Enterococci as a rapid beach management tool in Hawaiʻi

PI: Marek Kirs
The goal of this project was to design a rapid, simple, molecular-based water quality test that authorities can easily apply on Hawaiian beaches to increase hazard resilience of coastal communities. Standard coastal water quality testing techniques require 24-48 hours of culturing Enterococci bacteria, which often gives falsely high readings in Hawaiʻi from environmental sources. This newly developed method uses a specifically human-sewage-borne pathogen, Bacteroides, detected by rapid molecular tests, and is proving to give efficient and accurate detection of contamination to provide more timely notice and better protect public health.

By Rachel Lentz Coastal and Climate Science COE project Past Research Project

08 Mar: Mitigating climate change impacts: What drives thermal resiliency in Hawaiʻi’s coral reefs?

PI: Ruth Gates
This study aimed to understand the biology and physiology of corals, their symbiotic algae, and microbial communities that underpin different responses to bleaching events, why some coral colonies survive bleaching and others do not. Thermal resilience was tested in four coral species important to Hawaiʻi, examining the role of morphology, tissue thickness, and behavior of bacterial communities in bleaching recovery. Results showed that after two weeks at high heat, rice coral (Montipora capitate) was most resistant to bleaching, although all four species returned to normal after four weeks of recovery time. Most susceptible to bleaching was the lace coral (Pocillopora acuta), which has the thinnest tissues.

By Rachel Lentz Coastal and Climate Science COE project Past Research Project Water Resource Sustainability

08 Mar: The role of surface and groundwater inputs in driving water quality in Kāneʻohe Bay, Oʻahu

PI: Henrietta Dulai
The goal of this project was to identify submarine groundwater discharge locations and quantify groundwater and its derived nutrient flow into Kāneʻohe Bay, particularly as it varies with wet and dry seasonal cycles. The researchers found that most freshwater in nearby coral reefs derives from streams during the wet season, but during the dry season, input from groundwater increases 150%. These results have led to maps with quantification of groundwater discharge, and measurements of nutrient fluxes have identified several watershed hotspots of wastewater contamination.

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