11th Annual TCBES Symposium Abstracts
Thursday, April 15th, 2021
- Keynote Speaker
- Christian Giardina - Institute of Pacific Islands Forestry, USDA Forest Service
On this page:
Detecting suspect rapid ʻōhiʻa death trees via high-resolution visible imagery
Effective forest management requires access to current and accurate monitoring data, particularly in the midst of disturbance events like wildfires or sudden mortality outbreaks. Remote sensing data can play an important role in management decision-making, as long as the imagery has the spatial and spectral resolution to detect the phenomena of interest and the timeliness and geographic coverage to be useful. Here we present an integrated method for forest health monitoring at the individual-tree scale from Hawaii Island, which has been undergoing widespread native forest declines associated with “rapid ‘ohia death” (ROD). This approach, which includes multi-platform high-resolution visible wavelength remote sensing in conjunction with field sampling and confirmatory laboratory testing, has been used to quickly respond to new outbreaks and has helped illustrate the importance of ungulate activity in exacerbating mortality levels in affected regions.
Using Bioacoustics to Measure 'I'iwi Density at Hakalau Forest National Wildlife Refuge
Andre Van Nguyen
Since the arrival of human settlers to the Hawaiian archipelago, native forest birds have fallen victim to population declines, range shifts, and extinctions in response to the compounding effects of habitat loss, non-native species, and introduced diseases. Baseline information on the number and location of species becomes increasingly important to conserve our endemic avifauna. To deliver the full potential of bird conservation, it is essential to improve the current techniques by which birds are monitored. Traditional, human-based techniques are resource intensive and temporally and spatially limited. The reach of conservation and management actions is also hampered by decades-old funding discrepancies between Hawaiian and North American birds. Such shortcomings can deliver incomplete assessments of bird species, presenting hazardous outlooks for Hawai'i’s conservation-reliant avifauna that largely depend on management interventions for their persistence. Fortunately, recent advances in bioacoustics technologies are progressing wildlife monitoring objectives by improving spatiotemporal coverage at reduced costs. For this study I am using such acoustic technologies to monitor 'I'iwi (Drepanis coccinea), an emblematic Hawaiian honeycreeper recently listed for protection under the Endangered Species Act. More specifically, I am using a pair-sampling technique consisting of acoustic recorders and point transect distance sampling (PTDS) to measure population density along an elevational gradient at Hakalau National Wildlife Refuge on the island of Hawai'i. Acoustic surveys will occur concurrently with PTDS, allowing for calibration of 'I'iwi vocal activity with human-based density estimates. Our goal is to demonstrate the utility in using vocal activity as an index for 'I'iwi population density while providing an economical proof-of-concept for conservation monitoring of Hawaiian forest birds and other sound-producing taxa.
Incorporating Detection and Occupancy Coefficients of Pacific Islands Coral Reef Fishes into Biomass Estimation Procedures Indicates Biases of Current Methodology
Coral reef fishery management relies on visual surveys to monitor changes in population size or assemblage structure. The biomass estimates generated from underwater visual surveys make two assumptions: reef fishes are perfectly detected, and all suitable habitat is occupied. These assumptions are unlikely to be met, and failing to account for them can result in biased biomass estimates. Our objective was to assess how accounting for imperfect detection and occupancy influence reef fish biomass estimates throughout the Pacific. To accomplish this, we generated detection and occupancy coefficients for all reef fishes appearing in the 2010-2017 monitoring data generated by the Pacific Islands Fisheries Science Centers Coral Reef Ecosystem Program. We then applied these coefficients to generate a corrected biomass estimate and compared it to each species' original biomass estimate. We applied frequentist detection and occupancy modeling to 549 species of coral reef fishes representing 55 families from 5 regions of the Pacific. The occupancy- and detection-corrected biomass estimates suggest that current methods underestimate common species biomass. However, the biomass of larger-bodied predatory fishes seems to be overestimated by current assessment methods. Herbivorous fishes did not exhibit a consistent pattern, with some species' biomass being overestimated and others underestimated. Our results represent the first effort to apply frequentist models to multiple reef fish species and estimate biomass over large regional scales. While this approach has assumptions requiring validation, it highlights several areas where current survey methods could be improved by accounting for detection and occupancy.
Assessing the Brand name Marine Debris pollution from Southeastern shores of Hawai'i island
Michael D. Stone
Oceanic currents, also known as gyres, are wildly responsible for the formation of "garbage patches" in the oceans around the world. The North Pacific Subtropical Gyre in particular is responsible for the high density of marine debris washing ashore on the Southeastern shores of Hawai'i. Since 2013 Hawai'i Wildlife Fund (HWF) has been collecting name brands that wash up on the shores of Hawai'i island. We have all the data compiled from 2013 to the present day. In this talk, we will access the most common brand, material, and product that has been collected since 2013, and show the origins of these brand name products.
Linking plant litter and litter-dwelling arthropod functional traits to predict ecological interactions
Leaf litter and litter-dwelling arthropods play important roles in nutrient cycling and the development of soil on a geologically-young Hawai‘i island. Studying these interactions using a trait-based approach can give us insight into the ecological interactions that occur on a micro-scale. I will be studying the relationship between plant litter and litter-dwelling arthropod functional traits to predict their ecological interactions in a Hawaiian lowland wet forest setting.
A Global Signature of Extinction Risk in Marine Fishes
In the current biodiversity crisis, marine organisms are facing significant pressure and are experiencing extinction rates up to ten times higher than the background rate of extinction. Marine fish in particular face immense pressure from harvesting and have shown significant depopulation trends, suggesting they are at a high threat of extinction. In order to better understand the distribution of extinction risk I assessed how a range of demographic, ecological, and economic predictor variables are associated with extinction risk among 9,268 marine fishes. Predictor variable data was downloaded from the online fish database, fishbase.org. Extinction risk was determined using the International Union for Conservation of Nature’s (IUCN) Red List, which assigns assessed species to a hierarchical risk category based on their level of endangerment. Generalized linear mixed effects models were used to test for association between the predictor variables and extinction risk. Additionally histograms and T tests were used to examine the data bias of which species the IUCN has assessed. A number of variables were found to be significantly associated with extinction risk, including slower population doubling time, larger total length size, larger weight, higher market price, and commercially fished species. Additionally, there were pronounced data bias trends in what kinds of species the IUCN has assessed. Together these results suggest targets for conservation, show what types of species need more research to determine extinction risk, and highlight what types of marine fish may go extinct at higher rates in the near future.
How will mass bleaching events affect the prevalence of ciguatera on Hawaiian reefs?
Ciguatera fish poisoning (CFP) is caused by consuming reef fishes containing toxins produced by dinoflagellates in the genus Gambierdiscus. Changing reefscapes and diminished reef fish assemblages may increase the areal density and range of Gambierdiscus spp. However, it is not clear how the resulting changes to reef ecosystems may interact to influence the probability of ciguatoxic fishes and thus the risk of CFP to local communities dependent upon these fisheries. For example, coral bleaching driven by anthropogenic climate change results in the loss of live coral, increasing the availability of habitat for Gambierdiscus spp. However, herbivorous fishes regulate the algae dinoflagellates attach to and transfer ciguatoxins to higher trophic levels. It is suspected that loss of coral from bleaching events may lead to the increased probability of ciguatoxic fishes on reefs, but it is not clear how the protection of herbivores mediates the risk of CFP. Therefore, the objectives of this study are to evaluate the relationship between coral cover loss, herbivorous fish biomass, and the probability of the high-level predator, Roi (Cephalopholis argus), and an herbivore targeted by anglers, Kole (Ctenochaetus strigosus), of being ciguatoxic using a commercially available fluorescent receptor binding assay. Fishes will be sampled quarterly across six sites along west Hawaiʻi Island that experienced differential rates of loss and recovery of coral cover and split between areas open and closed to fishing. The results of the study will allow resource managers to better communicate the risk of CFP and mitigate the dangers of continuous climate change.
Natural History and Biogeography of Hawaiian Mushrooms
The Hawaiian Islands have been an important location for studies of evolution and biogeography due to their isolation in the Pacific Ocean and known geological history. While some groups—such as birds and angiosperms—have received extensive biogeography and natural history study for over a century, mushrooms (Agaricomycotina) have received comparatively less attention until the last several decades. From 1992 to 2007, our knowledge of the mushrooms occurring in the Hawaiian Islands grew from less than 100 species to over 600, but analyses of their ecologies and biogeographies are lacking. Therefore, we compiled an updated list of c. 700 mushrooms occurring in Hawaiʻi with associated ecological data, and provide the first large-scale summary of Hawaiian macrofungal biogeography and natural history. While knowledge of the biodiversity of Hawaiian mushrooms and tropical fungi in general is still very incomplete, we hope this initial assessment will stimulate further research in the taxonomy, biogeography, and natural history of Hawaiian macrofungi, and provide a baseline for further studies among both professional mycologists and amateur naturalists.
A multi-indicator approach to identify sewage pollution hotspots along the Hilo, Hawaiʻi coastline
Joseph Nakoa III
Nearshore water quality is a growing topic of concern, especially in coastal communities like Hilo, Hawai’i, where little has been done to assess the safety of recreational waters. Hilo is an important area of focus because of the many cesspools in use and the location of the municipal wastewater treatment plant outfall pipe just offshore. Traditional methods of quantifying the amount of sewage present in a marine environment are sometimes contradictory. This study uses a multi-indicator approach, composed of two fecal indicator bacteria (FIB): enterococci and Clostridium perfringens, nutrient concentrations, and stable isotope ratios in macroalgae, to identify areas of concern along the Hilo coastline. Additional work will be done to better understand the use of macroalgae as a sewage indicator by relating percent cover of dominant species to other sewage indicators and identifying differences in stable isotope ratios and nutrient retention between algal species. Preliminary results of this study show that most areas in Hilo consistently exceed the Hawai’i state standard for enterococci, but all stations are below the standard for Clostridium perfringens. This study will allow us to gain a better understanding of the extent of sewage pollution in Hilo. Final results will be shared with the Hawaiʻi Department of Health and the Hilo community upon completion.
MEGA Lab AR - a coral reef in your pocket
3D reconstruction techniques are being increasingly used to study benthic marine environments. This approach generates high-resolution 3D models of reef habitats which can be used by scientists to better understand these complex systems. These 3D models can also be used to communicate science through their integration into an augmented reality (AR) environment. AR allows a user to interact with a digital object that is superimposed in reality using a digital camera. The widespread adoption of smartphones allows this technology to be broadly accessible to the general public. The MEGA Lab AR application allows anyone around the world to view and interact with 3D models generated by scientists. Whether it’s used as an educational gadget for students, an outreach tool for the curious, or a way to share ideas with colleagues, this application immerses inquisitive minds into the world's coral reefs.
Automating urchin detection on high resolution benthic imagery using machine learning techniques
This project will develop and examine the capability of developing machine learning tools to accurately automate the identification of six common species of Pacific sea urchins from high resolution benthic imagery. Methods for benthic monitoring have been made more efficient over the past decade with the implementation of photoquadrats (Preskitt et al. 2004), digital video collection (Brown et al. 2004), and most recently, 3D reconstruction of benthic habitats (Burns et al. 2015). The 3D reconstruction process produces high resolution orthomosaics that can be used to characterize communities of benthic organisms. Advances in machine learning have led to automation of image processing, which allows ecologists to rapidly quantify ecological features from large-scale imagery. Removing the bottleneck of tedious manual image processing will broaden the impact and efficiency of long-term monitoring programs established by resource management agencies. The proposed study aims to combine 3D modeling of benthic habitats and computer vision to develop a technique for automating identification and enumeration of sea urchins on Hawaiian coral reef habitats.
Identifying locations of sewage pollution within a Hawaiian watershed for coastal water quality management actions
Tracy Wiegner (other co-authors include: Steven L. Colbert, Leilani M. Abayaa Jazmine Panelo, Kristina Remple, and Craig E. Nelson)
Locations of sewage pollution in the Puakō watershed, Hawai‘i Island, were identified through measurements of sewage indicators [fecal indicator bacteria, stable isotopes, nutrients] at groundwater wells and within Puakō’s and adjacent resorts’ shoreline waters. Dye tracer tests, water quality, δ15N macroalgal, and δ15N- and δ18O-NO3- measurements, and stable isotope mixing models assessed water quality impairment caused by different Onsite Sewage Disposal System (OSDS) types, and were used to predict water quality improvements from different future management actions.Sewage indicators were highest within Puakō’s shoreline waters, including: Enterococcus spp., Clostridium perfringens, human-associated Bacteroides, and δ15N-NO3-. Mixing model results using d15N- and d18O-NO3- suggest that sewage was the dominant NO3- source, comprising >40% at 10 of the 16 shoreline stations. δ15N macroalgae measurements confirmed the presence of sewage at most stations. In groundwater wells and at adjacent resorts’ shoreline waters, sewage indicators were low, and δ15NO3-was indicative of soils and fertilizers. Puakō dye tracer tests revealed that sewage reached the shoreline within 5 h to 10 d, and that OSDS type did not affect travel time. Water quality was similar in front of homes with different OSDS. In conclusion, sewage is largely entering the water table at Puakō, and the underlying geology controls the speed at which sewage reaches the shoreline, not OSDS type. Our findings highlight the need for improved sewage treatment and collection at Puakō.
THE HISTORY OF HILO’S HAMMERHEADS: RECONSTRUCTING CHANGES IN THE DISTRIBUTION AND ABUNDANCE OF JUVENILE SCALLOPED HAMMERHEAD SHARKS IN HILO BAY, HAWAI`I THROUGH THE USE OF TRADITIONAL ECOLOGICAL AND INDIGENOUS KNOWLEDGE
Scalloped Hammerhead (manō kihikihi) Sphyrna lewini is an imperiled coastal-pelagic shark found worldwide that uses nearshore, estuarine habitat during its first 1-2 years. In Hilo Bay, Hawai'i there have been anecdotal reports of a decline in Scalloped Hammerhead abundance, but no long-term monitoring data to determine the extent of the decline, if any, or causative factors. Therefore, the objectives of the proposed study are to evaluate the status and population trends of Scalloped Hammerhead in Hilo Bay using fisher interview data to estimate temporal and spatial trends in catch per unit effort (CPUE) and to reconstruct species distributions. We will also use acoustic telemetry to evaluate the current distribution and habitat use of Scalloped Hammerhead in Hilo Bay in order to compare to the estimates generated by fisher interview data. The expected products of the proposed project are a species distribution model predicting the occurrence of Scalloped Hammerhead pups under different physicochemical conditions in Hilo Bay; a dataset containing the transcribed interview data including estimates of CPUE; a geodatabase containing the data generated by interviewed fishers on their story maps; a geodatabase containing the relocation histories of Scalloped Hammerhead pups tagged with acoustic transmitters. These products will be delivered to state (Hawai'i Department of Land and Natural Resources), federal cooperators (e.g., National Marine Fisheries Service, Western Pacific Fisheries Regional Management Council, etc.) and local community groups and NGOs through annual reports and outreach events/meetings.
Comparison of Quantification Methods Used To Measure Success of Scleractinian Coral Populations at Papahānaumokuākea Marine National Monument
In this talk I will discuss three modern methodologies & photogrammetric techniques used to quantify the three-dimensional structures of scleractinian corals. I will review the precision of each method, how these techniques can be modified to answer various questions, and what types of real-world limitations exist when analyzing compound reef data. This particular case examination focuses on twelve total study sites, measured over two years. Each site is located within Papahānaumokuākea Marine National Monument, which is a pristine example of how protected marine areas provide researchers a chance to learn more about which specific influencers and diseases are diminishing reef-systems globally, and how various assemblages of scleractinian corals impact total abundance and diversity for all reef life.
Expanding the capacity for the preservation and restoration of native forest habitats on the Island of Hawaiʻi
Sebastian A.W. Wells
As the native forests of Hawaiʻi Island continue to face new threats in the form of invasive species, destructive pathogens such as Rapid ʻŌhiʻa Death (ROD), and stochastic events, the need for island-wide native forest rehabilitation continues to intensify. To address these ecologic and anthropogenic issues, the County of Hawaiʻi Real Property Tax Division has expanded their native forest dedication program to provide private landowners with reduced property tax rates for dedicating their land to native forest, functional forest, or successional forest land-use designations. With native forest Bill 178 being recently signed into law, ordinance number 20 60 establishes a dedication process for forest preservation and restoration for private property owners who have a minimum of 2.75 acres of contiguous native forest habitat. To support this new legislation, new resources were created to maximize enrollment rates and the success of the individuals who are participating in this community-based native forest restoration program. Examples of the new resources created specifically for this new legislation include a native, non-native/non-invasive plant species list to help individuals determine what types of plants they can incorporate into their native forest restoration endeavors and a management plan template that allows landowners to develop management plans without the help of a certified natural resource management professional. This new legislation, which is the first of its kind in the State, facilitates community-based native forest restoration projects by increasing multi-stakeholder participation in the active care and management of native forest habitats throughout the County of Hawaiʻi.
Collaborative efforts to reevaluate the vulnerability of Lalo in Papahānaumokuākea
As climate change accelerates globally, improved understanding of exposure and vulnerability to climate induced impacts becomes increasingly vital in navigating the future of atoll island communities. In this study atoll island communities are inclusive of islanders and the biological resources (sea turtles, shorebirds, monk seals, native fauna, coral habitats) that dwell and feed within the terrestrial and nearshore environment. Sea-level rise (SLR) is identified as the biggest threat to atoll island communities due to their low lying elevation (Woodroffe 2008). Papahānaumokuākea Marine National Monument (PMNM) is home to the only atoll islands located within Hawaiʻi. Lalo, also known as French Frigate Shoals is an open atoll consisting of a large, crescent-shaped reef. Numerous small, sandy islets have formed upon fossil reef platforms within the last 2,000 years. The main objectives of the project are to 1. Quantify the historical evolution of island area at Lalo from satellite and UAS derived imagery, 2. Quantify the recovery and evolution of islands at Lalo following Hurricane Walaka from satellite and UAS derived imagery, 3. Develop a collaborative survey to assess manager’s and expert’s specific needs, concerns, and opportunities for managing habitat and resources at Lalo. The final product of this project will be the development of a resiliency map that prioritizes habitat and communities that will continue to persist due to natural and managed resiliency efforts. Ultimately this work will guide the development of best management practices and strategies for the future of cultural and natural resources across Papahānaumokuākea.
Automating Coral Species Segmentation and Classification from High-Resolution Coral Reef Imagery
Coral reefs are exceptionally productive and valuable ecosystems. They support high levels of marine biodiversity and provide critical resources for human livelihood and well-being. Unfortunately, these environments are rapidly degrading worldwide and thus the availability of ecosystem services is in decline. Scientists have recently been using Structure-from-motion (SfM) photogrammetry to produce high-resolution 3D reconstructions of coral reef habitats. The models contain valuable data that allow scientists to better understand the ecology and biology of these highly complex ecosystems. Community composition data, for example, is currently obtained by manually annotating every colony on digital orthomosaics. While this approach produces useful ecological data, it is a substantially time-consuming process given a single plot may contain anywhere from hundreds to thousands of individual coral colonies. Considering the rapid ecosystem decline, innovative advancements are needed to automate and expedite this process. The objective of this project is to develop a reproducible machine learning (ML) workflow to automate the segmentation and classification of coral colonies from reef imagery. We used manually annotated and validated data as a training dataset for object detection models in order to determine which ML techniques are most accurate and efficient for this particular task. By expediting these repeatable and time-consuming tasks, we can create an automated data processing pipeline to be used for large-scale reef monitoring. Monitoring reef habitats at a larger spatial scale using 3D SfM along with ML techniques can greatly optimize coral reef research and aid in developing strategic conservation plans.
Analyzing and mapping cultural significant sites on the island of Kahoʻolawe
The island of Kahoʻolawe is situated off of the southwest coast of Maui and is the home to many significant cultural and archaeological sites. Archeological information suggests that Hawaiians arrived on this island at around 400 A.D.. From this time, there have been many kūʻahu, or ceremonial altars, that have been constructed on this island. These structures are usually found accompanied by offerings, or other items of cultural significance that are composed of organic materials that could be used as a record of what could have been on that island during the time of the altar construction and use. Text Analytics were used to dissect patterns in a large dataset with information of the significant items and structures that were found amongst 83 possible ceremonial sites. The Text Analytics approach was able to quantify the relative potential topics that could provide an insight into what organic materials were on that island, and the extent of what the people during that time would mostly use for these ceremonial sites. The altars and ceremonial data were spatially mapped to visualize these altars and their characteristics. Spatially mapping the significant cultural and archaeological sites provides important information on the island locations associated with all documented artifacts.
Friday, April 16th, 2021
- Kuaha Building Workshop
- Presented by Hālau ʻŌhiʻa
Patterns of morphological variation in an introduced population of Peacock Grouper Cephalopholis argus around Hawai'i Island
Morphological plasticity is an important attribute in defining the niche space of a species and can be predictive of the ability of an introduced species to establish itself. However, morphological plasticity in reef fishes, be they native or introduced, has not been extensively examined. Peacock Grouper, known locally in Hawai'i by their Tahitian name - Roi, Cephalopholis argus is a high level predatory reef fish that has spread throughout the Hawaiian Archipelago since the introduction of 2,385 individuals off Hawai'i and O'ahu in the 1950s. The objective of this study was to quantify the degree of morphological variability found within Roi populations around Hawai'i Island and evaluate the degree to which morphological variability was associated with the habitat occupied. We collected morphological data from photographs of 391 Roi collected during invasive species removal events around Hawai'i Island. Roi exhibited five distinct morphotypes: a heavy-bodied, robust form reminiscent of Epinephelus spp.; a slimmer and more streamlined form typical of Cephalopholis spp.; and a relatively robust form with a sloped head reminiscent of lutjanid snappers. The remaining two forms were intermediates of the a slimmer and more streamlined form and relatively robust form with a sloped head. The distribution of morphotypes was not associated with a clear spatial pattern, such as windward vs. leeward side of the island. However, the relative abundances of different morphotypes collected at a site were correlated with the composition of benthic habitat. The plasticity of Roi morphology potentially allows the species to occupy a broad range of habitats, particularly in the absence of other serranids and similar predatory species, and may be contributing to its successful establishment throughout the Hawaiian Archipelago.
Investigating the Role of the Gut Microbiome in Susceptibility to Avian Malaria in Hawaiian Honeycreepers
Elevated extinction rates among Hawaiian honeycreepers (subfamily Drepanidinae) due to mosquito-vectored avian malaria (Plasmodium relictum) showcase how introduced diseases can devastate naïve ecosystems. Most honeycreeper species persist in high-elevation refugia from disease, where lower temperature limits development of both mosquitoes and malaria parasites. However, as climate change raises global temperatures there is a risk that P. relictum may move up in elevation and cause a rapid loss of these avian refugia. ‘Amakihi (genus Chlorodrepanis) are the only honeycreepers that remain at high densities in low-elevation areas where malaria prevalence is high. We hypothesize that ‘amakihi persistence in these disease hotspots may be partially due to increased immunity to P. relictum conferred by their gut microbiota. To test this, we collected cloacal swabs and blood from wild Hawai‘i ‘Amakihi (C. virens, n = 185) and malaria resistant Warbling White-eyes (Zosterops japonicus, n = 179), at 16 sites of variable elevation (50-1750m) and malaria prevalence (20.0-67.3%) across the island of Hawai‘i. We used 16S ribosomal RNA gene sequencing to characterize the gut microbiome and qPCR to quantify P. relictum parasitemia intensity for each bird. Using an established bioinformatics pipeline and PERMANOVA model we assessed the relationship between microbiome composition and P. relictum infection and determined which bacterial taxa are associated with lower parasitemia intensity. Elucidating if microbial species are associated with increased protection against avian malaria in ‘amakihi is an essential first step in understanding host-microbiota-disease dynamics in this system and ultimately determining if probiotic based conservation strategies could mitigate honeycreeper decline.
Quantifying the Extent of Weather Buoy Damage to Coral Reefs at Lisianski Atoll in the Northwestern Hawaiian Islands
On March 28, 2018, a NOAA weather buoy located 186 nautical miles northwest of Kaua‘i Island, Hawai‘i, went adrift. After almost six months, the buoy was reported inside Papahānaumokuākea Marine National Monument on October 21, 2018, approximately 6.5 nautical miles northeast of Lisianski Island in the Northwestern Hawaiian Islands (NWHI). The buoy drifted to shore and became entangled on the coral reef habitat causing damage to the reef. 3D photogrammetry surveys of the benthic habitat were conducted in 2019 to quantify damage caused by the weather buoy’s mooring system. 3D reconstructions of the impacted reef habitat were digitally annotated to examine the area of live coral affected by the buoy grounding. The results of this work identify the type of damage occurring at two sites, including precise quantification of the 3D area and relative percentage of each type of damage. This study will provide information regarding the potential risk of buoy groundings on remote reef habitats.
Down to Digitize: Tracking Vitality of Corals in the Northwestern Hawaiian Islands through Geospatial Software
Carson Green and Rachel Williard
Coral reefs are some of the most productive ecosystems in the world. They cover less than 1% of the ocean floor yet are home to 25% of all marine life. The Papahānaumokuākea Marine National Monument is home to vast coral reefs. The monument is one of the largest marine protected areas in the world and it’s jurisdiction encompasses all of the Northwestern Hawaiian Islands (NWHI). Because the monument is protected, it is an ideal location to examine the changing environment and its effect on reefs without direct anthropogenic influence. Our research team decided to study the monument, focusing on quantifying vital rate changes in coral colonies from 2016 to 2017, with hopes of supporting conservation efforts for the future of coral reef ecosystems worldwide. To quantify reef characteristics, photographs taken of coral reefs in the NWHI were used to create 3D orthomosaics through photogrammetry methods. These orthomosaics were analyzed in ARCGIS and reef characteristics/vital rates were compared between years. Elements used to compare coral reef characteristics between different years included species richness, relative abundance, Shannon Diversity Index scores, & evenness frequencies. Our findings showed that all sites studied exhibit variability in coral community composition, and sites at French Frigate Shoals showed significantly more coral cover and coral abundance than Lisianski. Beyond analysis on habitat metrics, coral vital rates were used to model winners and losers of the reef, which is an ongoing study.
Unlocking resilience drivers to inform Pacific coral reef management
The objective of this project is to learn from Palmyra Atoll’s resilient coral reef ecosystem to inform actions that improve coral resilience to climate impacts elsewhere. Although 90% of live corals at Palmyra bleached during the 2015-16 bleaching event, there was no reduction in live coral cover from 2015-17. Palmyra’s highly resilient corals are exposed to nutrient rich water flowing from the lagoon out to sea. Palmyra’s abundant seabird and shark populations feed on pelagic prey, returning to the atoll and supplying it with nutrients through their guano and excrement, linking the pelagic and coastal ecosystems. These nutrients increase primary productivity around the atoll, and because corals can obtain up to 100% of their energy requirements heterotrophically, it is likely that seabird and shark-fueled plankton improves the corals’ ability to avoid starvation during bleaching events. Most inhabited islands, such as Hawai‘i, have reduced seabird and shark populations, and coral reefs in these areas have not been as resilient to thermal stress. Inspired by Palmyra’s resilience, the project will test the conditions under which fish-derived nutrients influence coral growth in a laboratory setting in Hawai‘i, where seabird and shark populations are below natural densities. We aim to understand if pelagic fish waste from fishing activities, an ample and unused resource, can be used to increase phytoplankton biomass to support corals’ ability to persist through a thermal stress event, thereby simulating the services that seabirds and sharks provide.
Effects of Chondria tumulosa on the 3D Habitat Complexity of Reefs on Pearl and Hermes Atoll
Chondria tumulosa is a type of red “nuisance” algae that has been identified in quite large amounts around the Pearl and Hermes Atoll in the North Western Hawaiian Islands in 2019. Since 2015, this Chondria has gone from rarely appearing, to creating thousands of square feet of algal mats around the atoll. To understand the outbreak of the algae we analyzed clipped digital elevation models from 2D orthomosaics to assess relationships, patterns, and effects on coral reefs throughout Pearl and Hermes. While coral cover, slope, surface complexity, and VRM varied, depth seems to have a significant correlation with chondria growth when observing long-term sites.
Comparison of photochemical efficiency among Hawaiian coral species housed in a closed-system aquarium
As global warming continues to impact corals and their surrounding habitats, studies on the complex mechanisms behind coral-algal symbiosis under conditions of light stress are becoming increasingly prevalent. While the algal-symbiont’s role in coral bleaching is fairly well-known, the specific relationships between algal photochemistry and coral photophysiology are much less understood. This study utilizes pulse amplitude modulated (PAM) fluorometry to compare the photochemical efficiency of in-hospite Symbiodiniaceae among three common Hawaiian coral species (Montipora capitata, Porites lobata, Pocillopora meandrina) housed in a closed-system aquarium. Light curves were performed on eight colonies of each species (n=8) using a diving-PAM fluorometer, where repetitive fluorescence measurements representing the maximum quantum yield and non-photochemical quenching of photosystem II were used to quantify photoinhibition during and following actinic light exposure. [results]. Tissue analyses should now be conducted to determine specific algal-symbiont communities within each species, as this information paired with the results of the present study will provide strong insight towards symbiont selectivity and the interspecific vulnerability of Hawaiian corals under future conditions of light stress.
View archived abstracts from previous years.