Geology topics

Research about Maui

Source-linked reports with geographic coverage including Maui.

At least 19 recordsLinked to original sources

USGS2025

Ten more years of the golden pheasant (Chrysolophus pictus) on Maui, Hawaiian Islands

Since the introduction of the Golden Pheasant ( Chrysolophus pictus ) to Haleakalā volcano, Maui, three decades ago, subsequent reports have hinted at an expansion of this nascent population. We draw from a variety of data sources to learn about this pheasant's present status on Maui. First, forest bird surveys conducted every five years revealed that the frequency of Golden Pheasant detections has greatly increased, and the bird has both maintained its former distribution and expanded eastward into Haleakalā National Park (NP). Second, reports to eBird from The Nature Conservancy's Waikamoi Preserve, where Golden Pheasants first appeared on Maui, demonstrate that the frequency of observations has increased and is strongly seasonal, predominantly in the spring. Third, autonomous recording units monitoring endangered forest birds recorded pheasants too, adding new locations. Finally, trail cameras set to monitor mammals picked up pheasants as well, showing males of two color morphs: original “wild-type” and “dark-throated.” Trail cameras also documented a small juvenile at Waikamoi Preserve and both females and males in Haleakalā NP. By “connecting the dots” of mapped occurrences, we traced the pheasant's progression through a narrow band of subalpine cloud forest with open understory, extending from Waikamoi Preserve eastward to upper Kīpahulu Valley, a distance of 14 km. In summary, this body of evidence supports the claim that the Golden Pheasant has established a self-sustaining population on Maui, and we propose that the species' success there may be attributed to the minimal influence of predators and the absence of competing gallinaceous birds in its preferred habitat.

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USGS2024

Identifying Pareto-efficient eradication strategies for invasive populations

Invasive species are a major cause of biodiversity loss and are notoriously expensive and challenging to manage. We developed a decision-analytic framework for evaluating invasive species removal strategies, given objectives of maximizing eradication probability and minimizing costs. The framework uses an existing estimation model for spatially referenced removal data—one of the most accessible types of invasive species data—to obtain estimates of population growth rate, movement probability, and detection probability. We use these estimates in simulations to identify Pareto-efficient strategies—strategies where increases in eradication probability cannot be obtained without increases in cost—from a set of proposed strategies. We applied the framework post hoc to a successful eradication of veiled chameleons ( Chamaeleo calyptratus ) and identified the potential for substantial improvements in efficiency. Our approach provides managers and policymakers with tools to identify cost-effective strategies for a range of invasive species using only prior knowledge or data from initial physical removals.

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USGS2024

Imogolite and allophane formed in saprolite of basalt on Maui, Hawaii

Inorganic gel and allophane collected from basaltic saprolite on Maul, Hawaii, and studied by Patterson in I964 were reexamined. The main constituent of the gel is imogolite, and gibbsite and allophane are the minor constituents. Electron and X-ray diffraction patterns, DTA curve, and an infrared spectrum of the gel are characteristic of imogolite. The allophane is virtually noncrystalline to X-rays but contains a small amount of imogolite in relatively short threads. High-resolution electron micrographs indicate differences in structural organization between allophane and imogolite and suggest crystallization of imogolite from allophane. The occurrence of imogolite as a weathering product has been reported in many localities from pyroclastic materials but not from massive rocks. Probably the exceptionally high rainfall, excellent subsurface permeability of the weathered material, and the low pH and high organic content of the leaching solution provide favorable conditions for formation of imogolite from basalt on Maul.

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USGS2022

Pharmaceuticals and personal care products in passive samplers at seven coastal sites off West Maui, Hawaiʻi:

Passive membrane samplers—semipermeable membrane devices and polar organic chemical integrative samplers—were deployed for 22 continuous days at 7 sites along the West Maui, Hawaiʻi, coastline in February and March 2017 to assess organic contaminants at shallow coral reef ecosystems from diverse upstream inputs. The distribution of organic compounds observed at these coastal sites showed considerable variability; high concentrations of microbially sourced organic compounds observed at all sites, with pentadecane as the predominant normal alkane, showed the relative importance of marine and microbial organic matter to the coastal carbon pool. Pharmaceuticals and personal care products, as well as flame retardants, were also detected at all sites. Of the seven sites sampled, the Kahekili Beach Park site had the highest number of unique contaminants and the Honokōwai Stream site had the highest concentrations of compounds. Two individual compounds, a flame retardant and a fragrance, were ubiquitous across the studied West Maui reefs, including at the least-developed site. A direct correlation to upstream land-use practices or legacy agricultural inputs was not readily observed since polychlorinated biphenyls, pesticides, herbicides, or insecticides were not detected. Results provide a snapshot of relative contaminant abundances as well as inputs to select nearshore environments along the West Maui coastline captured during the 2017 wet season, which was drier than expected. These data can be useful for understanding the range of stressors potentially affecting nearshore ecosystems, such as groundwater inputs and watershed runoff.

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USGS2022

Long-term groundwater availability in the Waihe‘e, ‘Īao, and Waikapū aquifer systems, Maui, Hawai‘i

Groundwater levels have declined since the 1940s in the Wailuku area of central Maui, Hawai‘i, on the eastern flank of West Maui volcano, mainly in response to increased groundwater withdrawals. Available data since the 1980s also indicate a thinning of the freshwater lens and an increase in chloride concentrations of pumped water from production wells. These trends, combined with projected increases in demand for groundwater in central Maui, have led to concerns over groundwater availability and have highlighted a need to improve general understanding of the hydrologic effects of proposed groundwater withdrawals in the Waihe‘e, ‘Īao, and Waikapū areas of central Maui. A numerical groundwater model was constructed to simulate the flow and salinity of groundwater in central Maui. The model simulates the effects of changes in groundwater withdrawals and recharge on water levels, freshwater-lens thicknesses, and chloride concentrations of pumped water from production wells. The model incorporates updated water-budget estimates of groundwater recharge from infiltration and direct recharge, seepage in stream channels, and inflow from inland areas. Mean annual groundwater recharge from infiltration and direct recharge was estimated using a daily water-budget model and the most current data, including the distributions of monthly rainfall and potential evapotranspiration, for the study area for nine historical periods from 1926 through 2012: 1926–69, 1970–79, 1980–84, 1985–89, 1990–94, 1995–99, 2000–04, 2005–09, and 2010–12. The water-budget model also estimated groundwater recharge based on one hypothetical scenario that used 1980–2010 rainfall and 2017 land cover. For the nine historical periods, estimated recharge from infiltration and direct recharge within the area of the groundwater model ranged from 30.4 million gallons per day (Mgal/d) during 2010–12 to 98.7 Mgal/d during 1926–69. Variability in recharge during these periods mainly reflects changes in rainfall and irrigation over time. Between 2010 and 2014, streamflow restoration in previously diverted streams resulted in an estimated increase in recharge from seepage in stream channels of about 12.5 Mgal/d. Average groundwater inflow of about 39.6 Mgal/d from inland, dike-intruded areas to the main area of interest was estimated from an existing island-wide numerical groundwater-flow model, which is at a larger scale and incorporates a greater number of simplifying assumptions. The numerical groundwater model developed for this study was calibrated to 1926–2012 transient water levels, vertical salinity profiles, and chloride concentrations of water pumped by production wells in the study area. The model was then used to evaluate one future recharge and six selected withdrawal scenarios, developed in consultation with the Maui Department of Water Supply, in terms of long-term changes in water level and 50-percent ocean-water salinity surface. The groundwater model was also used to simulate the future salinity of water withdrawn by existing and proposed production wells. The simulations were run to steady-state conditions, providing an estimate of the long-term effects of changes in withdrawal and recharge on the groundwater resource. Results of the simulated future withdrawal scenarios indicate that, relative to 2017–18 rates, the scenarios’ long-term effect of increased withdrawals ultimately leads to lower water levels and a higher 50-percent ocean-water salinity surface indicating a thinning of the freshwater lens. Results also indicate that the increased withdrawals produce some groundwater with chloride concentration below 250 milligrams per liter and some groundwater with higher chloride concentration. The amount of drawdown near production wells and the quality of water withdrawn from production wells is dependent on the rate and spatial distribution of the withdrawals. The model was also used to evaluate how groundwater availability may be affected for a drier recharge scenario based on a published study of future climate. Model results of the future recharge scenario indicate that the rate of groundwater recharge is a controlling factor for (1) water levels, (2) the 50-percent ocean-water salinity surface, and (3) the quality of water withdrawn from production wells in the Wailuku area. Coupled with reduced groundwater recharge (with all other factors remaining equal), the modeled future withdrawals in the scenario would tend to cause lower water levels, a higher 50-percent ocean-water salinity surface, and increased salinity of water withdrawn from production wells. The three-dimensional numerical groundwater model developed for this study utilizes the latest available hydrologic and geologic information and is a useful tool for understanding the long-term hydrologic effects of additional groundwater withdrawals in central Maui. The model has several limitations, including its non-uniqueness and inability to account for local-scale heterogeneities. Short-term effects of changes in recharge and withdrawals—and optimization of pumping rates to meet increased demand for water with acceptable salinity—are possible conditions for future simulation analyses.

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USGS2022

Characterizing mauka-to-makai connections for aquatic ecosystem conservation on Maui, Hawaiʻi

Mauka-to-makai (mountain to sea in the Hawaiian language) hydrologic connectivity – commonly referred to as ridge-to-reef – directly affects biogeochemical processes and socioecological functions across terrestrial, freshwater, and marine systems. The supply of freshwater to estuarine and nearshore environments in a ridge-to-reef system supports the food, water, and habitats utilized by marine fauna . In addition, the ecosystem services derived from this land-to-sea connectivity support social and cultural practices (hereafter referred to as socio-cultural) including fishing, aquaculture, wetland agriculture, religious ceremonies, and recreational activities. To effectively guide island resource management, a better understanding of the linkages from ridge-to-reef across natural and social usages is critical, particularly in the context of climate change, with anticipated increasing temperature and shifting precipitation patterns. The objective of this study was to identify spatial linkages that promote multiple and diverse uses, following the ridge-to-reef concept, at an island-wide scale to identify regions of high conservation importance for aquatic resources. We selected the Island of Maui as a study representative of many Pacific islands. Diverse datasets, including agricultural lands within watersheds, wetland locations, presence of stream species, indicators of freshwater input from streams, coral cover, nearshore fish biomass, socio-cultural data such as fishpond locations, wetland taro cultivation, beach recreation use, and lastly the dynamically downscaled Coupled Model Intercomparison Project Phase (CMIP5) future climate projections scenarios (Representative Concentration Pathway (RCP) 4.5 & 8.5) were used to examine the spatial linkages through hydrological connectivity from land to the sea. Zonation spatial planning software was used to prioritize areas of high management and conservation value and to help inform aquatic resources management. The resulting prioritized areas included many minimally disturbed watersheds in east Maui and western nearshore and coastal zones that are adjacent to diverse coral reefs. These results are driven by the importance of fish biomass and coral reef distribution as well as traditional wetland taro cultivation and coastal access points for recreation. These results underline the importance of examining ridge-to-reef systems for aquatic resource management and including important social and cultural values in resource management upon planning adaptation strategies for climate change. Improving our understanding of diverse natural and socio-cultural influences on habitat conditions and their values in these areas provides an opportunity to strategically plan future management and conservation actions.

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USGS2021

Population estimates and trends of three Maui Island-endemic Hawaiian Honeycreepers

Population monitoring is critical for informing the management and conservation of rare Hawaiian forest birds. In 2017, we used point-transect distance sampling methods to estimate population densities of birds on Haleakalā Volcano on east Maui island. We estimated the populations and ranges of three island-endemic Hawaiian honeycreepers, including the endangered ‘Ākohekohe ( Palmeria dolei ), the endangered Kiwikiu (Maui Parrotbill; Pseudonestor xanthophrys ), and the Maui ʻAlauahio ( Paroreomyza montana newtoni ). We examined population trends back to 1980, and our 2017 density estimates were the lowest ever recorded for each species. Most concerning was the status of Kiwikiu, with a 71% decline in population since 2001 to a current population of 157 (95% CI 44–312) birds. The population of ‘Ākohekohe similarly decreased by 78% to a current population of 1768 (1193–2411) birds. For both species, population declines were due to declines in density and contraction of ranges from lower elevations. Both species are now restricted to ranges of less than 3000 ha. We surveyed ~ 91% of the range of Maui ‘Alauahio and estimated a population of 99,060 (88,502–106,954) birds, a 41% decrease since the highest estimate in 1992. Contraction of ranges to higher elevations is consistent with evidence that the impacts of avian malaria are being exacerbated by global warming trends. Our results indicate that the landscape control of either avian malaria transmission or its vector ( Culex mosquitoes) will be a pre-requisite to preventing the extinction of endemic forest birds in Hawaii.

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USGS2020

Divergent movement patterns of adult and juvenile ‘Akohekohe, an endangered Hawaiian Honeycreeper

The movement patterns of birds across a landscape are often highly variable and influenced by complex interactions between individuals and environments. Because periods of movement can be marked by high mortality, especially among juvenile birds, understanding these patterns may be vital for the conservation of many bird species. However, these patterns can be challenging to quantify. We used radio‐telemetry to document the movement patterns of ‘Akohekohe ( Palmeria dolei ), an endangered Hawaiian Honeycreeper endemic to Maui Island, Hawai'i. This species is believed to be highly susceptible to mosquito‐transmitted avian malaria ( Plasmodium relictum ) and only breeds in high‐elevation wet forests on the windward side of east Maui (> 1715 m) that serve as mosquito‐free refugia. Over a 2‐yr period (2013–2014), we used radio‐telemetry and resightings of color‐banded birds to track the movements of juveniles ( N = 11) and adults ( N = 24) and quantified home ranges with minimum convex polygons (MCP) and 95% fixed kernels (KHR). Movement patterns and home range sizes of adult and juvenile ‘Akohekohe were significantly different, with adults having relatively small home ranges (0.57 ha, MCP; 1.09 ha, KHR) and juveniles moving greater distances and having larger home ranges (25.02 ha, MCP; 90.56 ha, KHR). Only juveniles moved into lower‐elevation forests that can support mosquito populations, at least seasonally. The absence of adults in this transitional malaria zone suggests that adult ‘Akohekohe cannot maintain long‐term home ranges in areas with an increased risk of malaria infection. In addition, the long‐distance movements of juveniles during the post‐fledging, pre‐breeding period likely increases their risk of contracting avian malaria and could be a key factor limiting the population of this species.

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USGS2020

Linking land and sea through an ecological-economic model of coral reef recreation

Coastal zones are popular recreational areas that substantially contribute to social welfare. Managers can use information about specific environmental features that people value, and how these might change under different management scenarios, to spatially target actions to areas of high current or potential value. We explored how snorkelers’ experience would be affected by separate and combined land and marine management actions in West Maui, Hawaiʻi, using a Bayesian Belief Network (BBN) and a spatially explicit ecosystem services model. The BBN simulates the attractiveness of a site for recreation by combining snorkeler preferences for coastal features with expert opinions on ecological dynamics, snorkeler behavior, and management actions. A choice experiment with snorkelers elucidated their preferences for sites with better ecological and water-quality conditions. Linking the economic elicitation to the spatially explicit BBN to evaluate land-sea management scenarios provides specific guidance on where and how to act in West Maui to maximize ecosystem service returns. Improving coastal water quality through sediment runoff and cesspool effluent reductions (land management), and enhancing coral reef ecosystem conditions (marine management) positively affected overall snorkeling attractiveness across the study area, but with differential results at specific sites. The highest improvements were attained through joint land-sea management, driven by strong efforts to increase fish abundance and reduced sediment; however, the effects of management at individual beaches varied.

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USGS2020

Hawaiian hoary bat (Lasiurus cinereus semotus) behavior at wind turbines on Maui

This study examined the activity of the endemic Hawaiian hoary bat (Lasiurus cinereus semotus) at wind turbines operated by Auwahi Wind Energy, LLC, on southern Maui Island, from August to November 2018. The research was conducted to assess the potential effect of wind speed and turbine operation on bat presence and behavior and compared information obtained from both acoustic monitoring and thermal videography. During the four months of nightly surveillance at four wind turbines, we observed 384 visual (videographic) and 244 acoustic detection events involving bats. Bats were infrequently detected, averaging 0.08 events per hour for both visual and acoustic samples. Detections occurred throughout the monitoring period, but bat presence was only evident for a fraction (acoustic: 30%; visual: 44%) of the turbine-nights sampled. Bats were present throughout the night, but detections exhibited a unimodal peak centered on the first third of the night, with events largely absent in the latter half of the night and no apparent seasonal trend towards earlier or later occurrence within nights. However, a decline in the visual detection rate was noted over the four-month period (a similar assessment was not available from acoustic samples due to missing data for much of the later months). Visual bat detections were not significantly correlated over nights (i.e., temporally), but were positively associated among turbines (i.e., spatially). Visual detections were generally brief (median = 9.0 sec), infrequent (median time between events = 49.0 min), and involved single passes (57%) largely comprised of a single bat (94%). The amount of time during which bats were visually observed amounted to only 0.05% of total videographic monitoring (2.5 hours of 5,066 total hours). Although not directly comparable to the video results because of differences in the volume of airspace sampled and nature of observation, acoustic detection events were similarly brief (median = 6.0 sec), infrequent (median time between passes = 38.8 min), and also composed only 0.05% of the total period of acoustic monitoring (1.6 hours of 3,036 total hours). Most visual observations (61%) were of individuals flying at some point during the event to within about 15 m of the turbine nacelle (machinery housing atop the monopole). Erratic flight paths were the most prevalent flight type with bats often repeatedly approaching and circling the nacelle. Terminal-phase (“feeding buzz”) calls were only noted in 3% of all acoustic events. Bats were most frequently detected visually at relatively low wind speeds (median = 3.4 m/sec); however, 10% of events occurred at wind speeds over 8.5 m/sec. Nightly bat detection rates for the four-month period of monitoring were negatively correlated with total daily precipitation. Generalized linear mixed model analysis confirmed that detection rates were negatively associated with wind speed and precipitation and indicated a positive relation with intermittent wind speed and its consequent effect on turbine blade rotation (i.e., frequent intervals of starting and stopping). The co-occurrence of bat detection obtained from videographic and acoustic monitoring methods was generally low, and in instances when individuals were visually observed, bats were detected acoustically during only 12% (within a 10-minute window), 22% (within a 2-hour window), and 56% (at some point during the entire night) of such events. Most visual detections (65% within a 2-hour window) lacking an acoustic detection involved bats observed flying within about 15 m of the turbine nacelle on which acoustic detector microphones were situated.

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USGS2019

Simulating land cover change impacts on groundwater recharge under selected climate projections, Maui, Hawaiʻi

This project developed an integrated land cover/hydrological modeling framework using remote sensing and geographic information systems (GIS) data, stakeholder input, climate information and projections, and empirical data to estimate future groundwater recharge on the Island of Maui, Hawaiʻi, USA. End-of-century mean annual groundwater recharge was estimated under four future land cover scenarios: Future 1 (conservation-focused), Future 2 (status-quo), Future 3 (development-focused), and Future 4 (balanced conservation and development), and two downscaled climate projections: a coupled model intercomparison project (CMIP) phase 5 (CMIP5) representative concentration pathway (RCP) 8.5 “dry climate” future and a CMIP3 A1B “wet climate” future. Results were compared to recharge estimated using the 2017 baseline land cover to understand how changing land management and climate could influence groundwater recharge. Estimated recharge increased island-wide under all future land cover and climate combinations and was dominated by specific land cover transitions. For the dry future climate, recharge for land cover Futures 1 to 4 increased by 12%, 0.7%, 0.01%, and 11% relative to 2017 land cover conditions, respectively. Corresponding increases under the wet future climate were 10%, 0.9%, 0.6%, and 9.3%. Conversion from fallow/grassland to diversified agriculture increased irrigation, and therefore recharge. Above the cloud zone (610 m), conversion from grassland to native or alien forest led to increased fog interception, which increased recharge. The greatest changes to recharge occurred in Futures 1 and 4 in areas where irrigation increased, and where forest expanded within the cloud zone. Furthermore, new future urban expansion is currently slated for coastal areas that are already water-stressed and had low recharge projections. This study demonstrated that a spatially-explicit scenario planning process and modeling framework can communicate the possible consequences and tradeoffs of land cover change under a changing climate, and the outputs from this study serve as relevant tools for landscape-level management and interventions.

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USGS2019

Estimated groundwater recharge from a water-budget model incorporating selected climate projections, Island of Maui, Hawai‘i

Demand for freshwater on the Island of Maui is expected to increase by 45 percent between 2015 and 2035. Groundwater availability on Maui is affected by changes in climate and agricultural irrigation. To evaluate the availability of fresh groundwater under projected future climate conditions and changing agricultural irrigation practices, estimates of groundwater recharge are needed. A water-budget model with a daily computation interval was used to estimate the spatial distribution of recharge on Maui for one present-day and two future-climate scenarios. All three scenarios used 2017 land cover. The two future-climate scenarios, including one wetter than the present-day scenario and one drier than the present-day scenario, were developed using available high-resolution downscaled climate projections. The drier future scenario was developed using projections for a Representative Concentration Pathway warming scenario during 2071–99 with total radiative forcing of 8.5 Watts per square meter by the year 2100 (RCP8.5 2071–99 scenario), whereas the wetter future scenario was developed using projections for a “Special Report on Emissions Scenarios” A1B emission scenario during 2080–99 (A1B 2080–99 scenario). For the RCP8.5 2071–99 scenario, projected mean annual recharge decrease for Maui is about 172 million gallons per day, or about 14 percent less than present-day recharge, which is estimated to be 1,232 million gallons per day. Recharge for the RCP8.5 2071–99 scenario is projected to decrease in 22 of Maui’s 25 aquifer systems, which are defined by the Hawaiʻi Commission on Water Resource Management. For the A1B 2080–99 future scenario, projected mean annual recharge increase for Maui is about 144 million gallons per day, or about 12 percent more than present-day recharge. Recharge for the A1B 2080–99 scenario is projected to increase in 17 of Maui’s 25 aquifer systems. Between the two future scenarios, a total of 11 aquifer systems show similar direction in drying (Kahului, Kama‘ole, Lualaʻilua, Makawao, Olowalu, Pāʻia, Ukumehame, Waikapū) or wetting (Honopou, Kawaipapa, and Waikamoi) changes for recharge. Selectively modifying the climate inputs for the A1B 2080–99 scenario indicates that the projected changes in rainfall account for most of the projected changes in recharge for Maui’s 25 aquifer systems. However, projected changes in reference evapotranspiration and forest-canopy evaporation also can account for a substantial part of the projected changes in recharge where changes in reference evapotranspiration are relatively large and where changes in forest-canopy evaporation extend across large forested areas. Projected changes in daily rainfall frequency have a relatively small but non-negligible impact on recharge estimates.

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USGS2019

Coral skeleton δ15N as a tracer of historic nutrient loading to a coral reef in Maui, Hawaii

Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δ 15 N) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources. Our results show a dramatic increase in coral δ 15 N values after 1995, corresponding with the implementation of biological nutrient removal at the nearby Lahaina Wastewater Reclamation Facility (LWRF). High δ 15 N values are known to be strongly indicative of denitrification and sewage effluent, corroborating a previously suggested link between local wastewater injection and degradation of the reef environment. This record demonstrates the power of coral skeletal δ 15 N as a tool for evaluating nutrient dynamics within coral reef environments.

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USGS2019

Hawaiian hoary bat (Lasiurus cinereus semotus) activity, diet and prey availability at the Waihou Mitigation Area, Maui

Habitat use, diet, prey availability, and foraging ecology of the endangered Hawaiian hoary bat (Lasiurus cinereus semotus, Vespertilionidae), was examined in the east Maui region inclusive of the Waihou Mitigation Area, Pu‘u Makua Restoration Area and the wind energy facility operated by Auwahi Wind Energy, LLC. The study was conducted to inform the mitigation and management requirements of Auwahi Wind Energy. Acoustic monitoring over the three-year period demonstrated that bats are present and actively forage year-round at the Waihou Mitigation Area. Over an 8-month span, 11 bats were uniquely color-banded and released, 3 of which were pregnant or lactating females, and highlights the importance of the area to breeding residents. Our study included the first genetic analysis of Hawaiian hoary bat diet, and confirms the inclusion of Coleoptera, Lepidoptera, Diptera, Hemiptera, and Blattodea among the prey items of this bat identified in previous microscopy-based studies. Hawaiian hoary bats consumed both native and non-native insect species, including several invasive species damaging to crop agriculture. Moths were the primary dietary component, both in prevalence among individual bats and the proportion of gene sequence counts. Through genetic analysis, we identified 18 Lepidoptera families (dominated by Noctuidae, Geometridae, Crambidae, Oecophoridae and Tortricidae) including 24 genus- or species-level taxa. Lepidoptera collected as caterpillars directly from vegetation did not appear in the diet of the 8 bat guano samples at the genus or species level. However, the occurrence of moth larva on native plants suggests that reforestation that includes host plants for these insect families may provide food for locally foraging bats.

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USGS2018

Carbonate system parameters of an algal-dominated reef along west Maui

Constraining coral reef metabolism and carbon chemistry dynamics are fundamental for understanding and predicting reef vulnerability to rising coastal CO 2 concentrations and decreasing seawater pH. However, few studies exist along reefs occupying densely inhabited shorelines with known input from land-based sources of pollution. The shallow coral reefs off Kahekili, West Maui, are exposed to nutrient-enriched, low-pH submarine groundwater discharge (SGD) and are particularly vulnerable to the compounding stressors from land-based sources of pollution and lower seawater pH. To constrain the carbonate chemistry system, nutrients and carbonate chemistry were measured along the Kahekili reef flat every 4 h over a 6-d sampling period in March 2016. Abiotic process – primarily SGD fluxes – controlled the carbonate chemistry adjacent to the primary SGD vent site, with nutrient-laden freshwater decreasing pH levels and favoring undersaturated aragonite saturation (Ω arag ) conditions. In contrast, diurnal variability in the carbonate chemistry at other sites along the reef flat was driven by reef community metabolism. Superimposed on the diurnal signal was a transition during the second sampling period to a surplus of total alkalinity (TA) and dissolved inorganic carbon (DIC) compared to ocean end-member TA and DIC measurements. A shift from net community production and calcification to net respiration and carbonate dissolution was identified. This transition occurred during a period of increased SGD-driven nutrient loading, lower wave height, and reduced current speeds. This detailed study of carbon chemistry dynamics highlights the need to incorporate local effects of nearshore oceanographic processes into predictions of coral reef vulnerability and resilience.

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USGS2017

The use of passive membrane samplers to assess organic contaminant inputs at five coastal sites in west Maui, Hawaii

Five passive membrane samplers were deployed for 28 continuous days at select sites along and near the west Maui coastline to assess organic compounds and contaminant inputs to diverse, shallow coral reef ecosystems. Daily and weekly fluctuations in such inputs were captured on the membranes using integrative sampling. The distribution of organic compounds observed at these five coastal sites showed considerable variation; with high concentrations of terrestrially sourced organic compounds such as C29 sterols and high molecular weight n -alkanes at the strongly groundwater-influenced Kahekili vent site. In comparison, the coastal sites were presumably influenced more by seasonal surface and stream water runoff and therefore had marine-sourced organic compounds and fewer pharmaceuticals and personal care products. The direct correlation to upstream land-use practices was not obvious and may require additional wet-season sampling. Pharmaceuticals and personal care products as well as flame retardants were detected at all sites, and the Kahekili vent site had the highest number of detections. Planned future work must also determine the organic compound and contaminant concentrations adsorbed onto water column particulate matter, because it may also be an important vector for contaminant transport to coral reef ecosystems. The impact of contaminants per individual (such as fecundity and metabolism) as well as per community (such as species abundance and diversity) is necessary for an accurate assessment of environmental stress. Results presented herein provide current contaminant inputs to select nearshore environments along the west Maui coastline captured during the dry season, and they can be useful to aid potential future evaluations and (or) comparisons.

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USGS2017

Rigorously valuing the role of coral reefs in coastal protection: An example from Maui, Hawaii, U.S.A.

The degradation of coastal habitats, particularly coral reefs, raises risks by exposing communities to flooding hazards. The protective services of these natural defenses are not assessed in the same rigorous, economic terms as artificial defenses such as seawalls, and therefore often not considered in decision-making. Here we present a new methodology that combines economic, ecological, and engineering tools to provide a rigorous financial valuation of the coastal protection benefits of coral reefs off Maui, Hawaii, USA. We follow risk-based valuation guidelines to quantitatively estimate the risk reduction benefits from coral reefs in terms of annual expected benefits in economic terms. Our ultimate goal is to identify how, where, and when coral reefs provide the most flood reduction benefits under current and future climates to inform reef conservation and management priorities.

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USGS2016

Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

Study region The study region encompasses the nearshore, coastal waters off west Maui, Hawaii. Here abundant groundwater—that carries with it a strong land-based fingerprint—discharges into the coastal waters and over a coral reef. Study focus Coastal groundwater discharge is a ubiquitous hydrologic feature that has been shown to impact nearshore ecosystems and material budgets. A unique combined geochemical tracer and oceanographic time-series study addressed rates and oceanic forcings of submarine groundwater discharge at a submarine spring site off west Maui, Hawaii. New hydrological insights for the region Estimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222 Rn ( t 1/2 = 3.8 d) mass balance model. Such estimates were complemented with a novel thoron ( 220 Rn, t 1/2 = 56 s) groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

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