2017 Maunalua Bay Case Study

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    Modeling Sediment Inputs to Maunalua Bay
    ( 2017-05-03) Antaky, Carmen ; Payne, Courtney ; Langston, Blaire ; Harrison, Tanya ; Martin, Brendan ; Oleson, Kirsten ; Crow, Susan
    Mālama Maunalua identified polluted runoff and sediment as the number one threat to Maunalua Bay. Sediment is one of the primary land-based threats to corals and other marine organisms because it decreases light availability, smothers coral and alters habitats. Rain runoff transports sediment through streams and into the bay. In Maunalua Bay, runoff is high due to increased human populations and stream channelization. This stream channelization causes water to move downstream at a faster than normal rate and increases the amount of sediment. We review some options for homeowners to mitigate the amount of sediment reaching the streams. To create effective management solutions for sediment pollution in the bay, we modeled the current sediment exports. We analyzed the contributions of each watershed and correlations with land use type. We found that most sediment is retained in the upper part of the watershed in forested areas, and that most outputs come from Waialaenui and Wailupe. We suggest that any stream restoration activities should focus on the Waialaenui and Wailupe as this will have the most drastic effect on sediment loads.
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    Economic Analysis of Maunalua Bay
    ( 2017-05-08) Andreyka, Natalie ; Arnott, Chelsea ; Tanigawa, Sara ; Yazzie, Aissa ; Oleson, Kirsten ; Crow, Susan
    The economic value generated by Maunalua Bay is not well understood, but greatly needed. This basic monetary value is essential in understanding how the bay supports the livelihoods of business owners and their employees in the community and across the island. To better assess this figure, we developed a survey specifically for recreational, commercial businesses who operate within Maunalua Bay. However, the majority of businesses declined to participate due to the survey approach, survey format, and/or existing tension with associated community conservation groups. The initial project goal to understand the economic value of Maunalua Bay to recreational, commercial operating businesses was not achieved due to an extremely low response rate. The data collected from completed surveys are not included in the report, as it is not a complete representation of the community we hoped to engage. Instead, we intend to better understand and improve how students connect with commercial operators in Maunalua Bay and inform future valuation efforts by offering these recommendations: 1. Understand the historic and current relationship between businesses and conservation community groups 2. Develop that relationship through one-on-one engagement and “talk story” sessions 3. Create a mutually beneficial economic assessment of Maunalua Bay 4. Use the assessment to better plan management strategies that utilize business relationships
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    Effects of Invasive Algae Removal Group
    ( 2017-05-08) Ching, Casey ; Char, Jared ; Nakama, Rylen ; Riley, Paul ; Watkins, Genelle ; Crow, Susan ; Oleson, Kirsten
    A sudden shift in stable states, from a native seagrass (Halophila hawaiiana) and native algae dominated habitat to one overrun by invasive algae, has taken place in Maunalua Bay. In addition to channelization of water bodies, and the resulting sedimentation due to runoff, mudweed and gorilla ogo invasions have been correlated with alterations to regional sediment catch and therefore, the ecology of the bay. The presence of mudweed results in increased sediment levels that smother native seagrass beds allowing mudweed to outcompete native seagrass and algae. The Huki Project in Maunalua Bay is a large-scale invasive algae removal operation targeting Mudweed (Avrainvillea amadelpha) that aims to clear the dominating algae from Maunalua Bay’s ecosystem. The presence of mudweed in Maunalua Bay undoubtedly influences the composition of local invertebrate assemblages. Invasive algae provides habitat for amphipods, molluscs, and polychaete worms, all of which are prey species for dominant macrofauna and forage-feeding, predatory fishes. Benthic-dwelling invertebrates provide a crucial prey base for predatory fishes, fulfilling a key role in marine food webs through the provision of nutrients to native and non-native fish species. Therefore, invertebrate assemblages are helpful indicators of the fish populations due to dependence of fish on a variety of factors provided by invasive algae such as prey availability and shelter during larval stages. As primary users of the resource, fishers’ perspectives and direct observations within Maunalua Bay include valuable knowledge of changes happening within the area. Incorporating human dimensions is an important factor within the scope of this project, not only with citizen science volunteers to yield scientific outcomes, but local community who regularly benefit from the resource. Ensuring the needs of the individuals directly connected to areas being restored is a major concern and fishermen were targeted in this project as citizens directly affected by the Huki Project. In order to understand changes to Maunalua Bay, measurements of fish population diversity, abundance, and biomass were taken across the Paiko area, literature of seagrass and invertebrate communities at Maunalua Bay were examined, fishermen were surveyed for perspectives, and historical data about the area was examined. Invertebrate communities have been found to shift post-removal of mudweed to communities commonly found among native algae. Fish biomass was very low, with average biomass at 0.57 g/m2 during daytime observations and 0.64 g/m2 during a single night observation. Uouoa (Neomyxus leuciscus) and kaku (Sphyraena barracuda) were observed nearshore outside of study plots. Fishermen were mostly targeting ‘o‘io and papio and 11% of fishermen caught fish while surveyed and 11% usually caught something regularly. Most fishermen (89%) thought that fish populations are decreasing.
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    Water Quality in Maunalua Bay
    ( 2017-05-03) Harmon, Kristen ; Lariosa, Kelly ; Markel, Amy ; Torigoe, Stacey ; Wehr, Nate ; Crow, Susan ; Oleson, Kirsten
    In 2002, the Hawaii State Department of Health declared Maunalua Bay an impaired water body, indicating that pollution levels do not meet state standards for public safety. Causes of declining water quality in the bay include: increased urban development, the use of pesticides for landscaping, and alterations of natural streams. These human-induced changes have resulted in increased levels of nutrients, chlorophyll, and turbidity in the bay, which decreases native seagrass and coral health and encourages invasive algal presence and sand accumulation. Despite knowledge of these issues, few efforts have been successful in limiting human impacts on water quality. Therefore, our group has taken steps to characterize water quality in Maunalua Bay, to test methods for water quality assessment, and develop recommendations for constructing a Quality Assurance Project Plan to allow for consistent monitoring of water quality in the bay and facilitate the release of information to stakeholders and community members.