Decadal trends and coral acclimatization at Malaukaʻa Fringing Reef, Kāneʻohe Bay, Oʻahu, Hawaiʻi

Globally, coral reefs are under threat from climate change and increasingly frequent bleaching events. However, corals in Kāneʻohe Bay have repeatedly shown resilience and the ability to acclimatize to rising temperatures and increased frequencies of bleaching events. The Malaukaʻa fringing reef -first surveyed in 2000- is revisited to compare species composition and percent cover of corals, algae, and mixed sand to investigate how the reef has fared over 18 years. Despite climate change-induced temperature increases and two major bleaching events, the fringing reef saw no significant change in total coral cover percent, nor a change in percent cover of the two dominant reef-building corals: Montipora capitata and Porites compressa. However, the loss of two coral species and addition of one new coral species between surveys indicates that while the fringing reef remains intact, a shift in species composition has occurred. While locally rare species from the 2000 study were not found in 2018, the reef remains. The survival of the fringing reef studied indicates resilience and suggests these Hawaiian corals are capable of acclimatization to climate change and bleaching events. A reciprocal transplant experiment was also conducted to determine if calcification (linear extension and accretion) for M. capitata and P. compressa varied between two sites 600 meters apart at either end of the surveyed reef and whether or not genetics or environmental factors were responsible for the differences. Linear extension did not vary between sites for either species, however accretion (measured as change in mg g -1 d -1) was significantly different between sites for P. compressa. Differences in accretion following transplantation suggest both environment and genetics impacted calcification of P. compressa in Kāneʻohe Bay.M-ECO

Expanding cold-water coral reef knowledge towards deep-sea ecosystem management

The deep sea is our planet’s largest and least explored ecosystem. Once thought to be a barren abyss devoid of life, we have learned the deep sea is home to diverse ecosystems. One such deep-sea ecosystem that supports biodiversity is cold-water coral (CWC) reefs. Less studied than their tropical counterparts, CWC reefs provide a range of ecosystem services such as carbon storage, pharmaceutical development, and fisheries. Threats from climate change and increasing anthropogenic deep-sea activity make protecting and managing CWC reef futures exceptionally important. Scientific advances over the last decades have allowed us to better understand CWC reef ecosystems, though we remain far off from achieving effective ecosystem management. The overall aim of this thesis is to guide CWC reef management through expanding knowledge of these ecosystems. Despite the majority of CWC reef area being composed of dead framework, most research has focused on understanding live coral responses to climate change. Dead framework supports the highest levels of biodiversity in a CWC reef system and contributes significantly to carbon and nitrogen cycling. Live corals and dead coral skeletons are vulnerable to different environmental stressors. To understand reef composition and accurately predict their futures under climate change, the proportion of live coral colonies to the entire reef structure must be quantified. Chapter 2 of this thesis guides CWC reef management through increasing our knowledge of depth’s role in driving live and dead reef proportions. In Chapter 2, the live and dead proportions of CWC Solenosmilia variabilis reefs are quantified across four seamount features in the southwest Pacific Ocean. Images of CWC reefs are analysed with significant differences in the proportions of live coral between reefs at the Louisville Seamount Chain and Graveyard Seamount Complex. Depth is identified as a driver of live and dead reef proportions in these regions, with a larger proportion of live coral at shallow depths and dead intact framework at deeper depths. Additionally, the proportion of live coral in the Graveyard Seamount Complex remained stable between 2015 and 2020, despite significant differences in the surface areas of live coral, dead intact framework, and the reef. These results indicate reef proportions can be used to estimate the amount of dead intact framework threatened by the shallowing aragonite saturation horizon (ASH) due to ocean acidification at each site, which can help inform which sites could be protected as possible climate change refugia. Identifying depth as a driver of reef proportions quantifies reef health, identifies reef threats, and predicts reef impacts, all of which increases our knowledge of current and future reef conditions. Ocean acidification (OA) is a critical stressor and leads to dissolution of exposed calcium carbonate (CaCO3) in aragonite-undersaturated waters — a direct threat to dead CWC skeletons. This increased coral porosity from climate stressors threatens the structural integrity of the entire reef framework and could lead to a direct loss of habitat through crumbling. Laboratory studies have largely explored how skeletons grown under favourable conditions respond to exposure in OA conditions. We do not yet know if CWC skeletons grown in OA conditions are as robust as those grown in favourable conditions or if CWC skeletal structures are built differently in ideal and OA conditions. Chapter 3 of this thesis guides CWC reef management through increasing our knowledge of the 3-dimensional (3D) crystallographic structure of CWC. In Chapter 3, 3D volumes of CWC skeletal samples from above and below the ASH are compared using Electron Backscatter Diffraction (EBSD). Aragonite needles grow radially from Rapid Accretion Deposits (RAD) which join with neighbouring crystal structures to create the skeletal building blocks called sclerodermites. From large RADs, sequential imaging shows aragonite needles radiate with a preferred growth direction perpendicular to the calcification interface before rotating out of plane. Crystal size and orientation are compared between samples collected from above and below the ASH to understand differences in skeletal structure and better predict reef futures under OA. Neither aragonite crystal size or sclerodermite length were significantly different between the sample taken from below and above the ASH. Increasing our understanding of CWC 3D crystallographic structure above and below the ASH quantifies reef health, identifies reef threats, and predicts reef impacts, increasing our knowledge of current and future reef conditions. There are more CWC reefs in the world which have not yet been discovered, and thus cannot be managed. Therefore, increasing global capacity to carryout baseline deep-sea research is crucial to ensuring adequate protection and management for these vulnerable marine ecosystems. Limited at-sea training opportunities make it difficult to ensure the next generation of deep-sea scientists are properly trained in sea-going research methods. However, telepresence and remote learning can be used to increase the number of active participants on deep-sea expeditions. Chapter 4 of this thesis guides CWC reef management through increasing our knowledge of the effectiveness of virtual ship-to-shore training for increasing deep-sea capacity. Chapter 4 explores the 2021 iMirabilis2 expedition’s use of telepresence to virtually involve early career researchers from several countries in deep-sea science. Post expedition, a survey of onshore participants was conducted to assess and quantify the effectiveness of the peer-to-peer early career researcher ship-to-shore scheme. During the expedition, live, interactive training via WhatsApp and Zoom was accessed more than traditional static, unidirectional methods of blog posts and pre-recorded videos. All respondents either agreed or strongly agreed the scheme provided an inclusive and accessible platform to share deep-sea science. These results suggest similar schemes could be used to supplement shorter duration at-sea training or used prior to a seagoing experience to better prepare early career researchers, increasing inclusivity. Creating an inclusive and accessible platform to virtually share at-sea deep-sea science increases capacity for deep-sea exploration which can lead researchers to discover more CWC reefs. Through quantifying reef health, identifying reef threats, predicting reef impacts, and increasing capacity for deep-sea exploration, this thesis expands knowledge of CWC reef ecosystems to guide deep-sea ecosystem management

Ship-to-shore training for active deep-sea capacity development

Sailing on scientific expeditions as an early career researcher (ECR) offers the beneficial opportunity to gain field experience and training. However, the number of available berths to achieve the scientific goals of an expedition limits the number of onboard participants. Telepresence and remote learning can be utilized to increase the number of active participants, broadening the reach of capacity development. The 2021 iMirabilis2 expedition on board the Spanish Research Vessel Sarmiento de Gamboa used telepresence to virtually involve ECRs from several countries in deep-sea science. One year post-expedition, a survey of onshore participants was conducted to assess and quantify the effectiveness of the peer-to-peer ECR ship-to-shore scheme. During the expedition, live, interactive training via WhatsApp and Zoom was utilized by onshore ECRs more than traditional static, unidirectional methods of blog posts and pre-recorded videos. All respondents either agreed or strongly agreed that the scheme provided an inclusive and accessible platform to share deep-sea science. These results suggest similar schemes could be used to supplement shorter-duration at-sea-training, used prior to a seagoing experience to better prepare ECRs, or to allow members of the science community unable to join an expedition in person to actively participate remotely, increasing inclusivity

Coral Resilience at Malauka`a Fringing Reef, Kāneʻohe Bay, Oʻahu after 18 years

Globally, coral reefs are under threat from climate change and increasingly frequent bleaching events. However, corals in Kane’ohe Bay, Hawai’i have demonstrated the ability to acclimatize and resist increasing temperatures. Benthic cover (i.e., coral, algae, other) was compared over an 18 year period (2000 vs. 2018) to estimate species composition changes. Despite a climate change induced 0.96 ◦C temperature increase and two major bleaching events within the 18-year period, the fringing reef saw no significant change in total coral cover (%) or relative coral species composition in the two dominant reef-building corals, Porites compressa and Montipora capitata. However, the loss of two coral species (Pocillopora meandrina and Porites lobata) and the addition of one new coral species (Leptastrea purpurea) between surveys indicates that while the fringing reef remains intact, a shift in species composition has occurred. While total non-coral substrate cover (%) increased from 2000 to 2018, two species of algae (Gracilaria salicornia and Kappaphycus alvarezii) present in the original survey were absent in 2018. The previously dominant algae Dictyosphaeria spp. significantly decreased in percent cover between surveys. The survival of the studied fringing reef indicates resilience and suggests these Hawaiian corals are capable of acclimatization to climate change and bleaching events.publishedVersio

Coral Resilience at Malauka`a Fringing Reef, Kāneʻohe Bay, Oʻahu after 18 years

Globally, coral reefs are under threat from climate change and increasingly frequent bleaching events. However, corals in Kane’ohe Bay, Hawai’i have demonstrated the ability to acclimatize and resist increasing temperatures. Benthic cover (i.e., coral, algae, other) was compared over an 18 year period (2000 vs. 2018) to estimate species composition changes. Despite a climate change induced 0.96 ◦C temperature increase and two major bleaching events within the 18-year period, the fringing reef saw no significant change in total coral cover (%) or relative coral species composition in the two dominant reef-building corals, Porites compressa and Montipora capitata. However, the loss of two coral species (Pocillopora meandrina and Porites lobata) and the addition of one new coral species (Leptastrea purpurea) between surveys indicates that while the fringing reef remains intact, a shift in species composition has occurred. While total non-coral substrate cover (%) increased from 2000 to 2018, two species of algae (Gracilaria salicornia and Kappaphycus alvarezii) present in the original survey were absent in 2018. The previously dominant algae Dictyosphaeria spp. significantly decreased in percent cover between surveys. The survival of the studied fringing reef indicates resilience and suggests these Hawaiian corals are capable of acclimatization to climate change and bleaching events

Reciprocal transplant coral growth rates for Porites compressa and Montipora capitata in Kāneʻohe Bay, Oʻahu, Hawaiʻi, 2018

This datasets consists of growth rates for coral fragments from the species Porites compressa and Montipora capitata in Kāneʻohe Bay, Oʻahu, Hawaiʻi, 2018. A reciprocal transplant experiment was conducted at Malauka'a fringing reef and accretion (buoyant weight) and linear extension were quantified at the end of the 50-day experiment

Human-bottlenose dolphin interactions within wildlife tourism, ocean recreation and fisheries

Bottlenose dolphins (Tursiops truncatus and Tursiops aduncus; BND) live in coastal waters, prompting frequent contact with humans. Interaction with BND can be either planned (e.g. swim-with-dolphin experiences) or chance (e.g. BND surfing on boat wakes). These charismatic cetaceans are common in many forms of wildlife tourism, including marine wildlife tours, swim-with-dolphin experiences and hand feeding. BND also interact with humans by chance during ocean recreation activities, such as surfing, swimming and boating. Within fisheries, there is both cooperation and conflict between humans and BND. Through a literature review, this paper highlights the effects such interactions cause to both BND and humans with a focus on wildlife tourism, ocean recreation and fisheries.</p

Acclimatory plasticity drives differences in reef-building coral calcification rates

Coral reefs are susceptible to climate change, anthropogenic influence, and environmental stressors. However, corals in Kāneʻohe Bay, Hawaiʻi have repeatedly shown resilience and acclimatization to anthropogenically-induced rising temperatures and increased frequencies of bleaching events. Variations in coral and algae cover at two sites—just 600 m apart—at Malaukaʻa fringing reef suggest genetic or environmental differences in coral resilience between sites. A reciprocal transplant experiment was conducted to determine if calcification (linear extension and dry skeletal weight) for dominant reef-building species, Montipora capitata and Porites compressa, varied between the two sites and whether or not parent colony or environmental factors were responsible for the differences. Despite the two sites representing distinct environmental conditions with significant differences between temperature, salinity, and aragonite saturation, M. capitata growth rates remained the same between sites and treatments. However, dry skeletal weight increases in P. compressa were significantly different between sites, but not across treatments, with linear mixed effects model results suggesting heterogeneity driven by environmental differences between sites and the parent colonies. These results provide evidence of resilience and acclimatization for M. capitata and P. compressa. Variability of resilience may be driven by local adaptations at a small, reef-level scale for P. compressa in Kāneʻohe Bay

Acclimatization Drives Differences in Reef-Building Coral Calcification Rates

Coral reefs are susceptible to climate change, anthropogenic influence, and environmental stressors. However, corals in Kāneʻohe Bay, Hawaiʻi have repeatedly shown resilience and acclimatization to anthropogenically-induced rising temperatures and increased frequencies of bleaching events. Variations in coral and algae cover at two sites&mdash;just 600 m apart&mdash;at Malaukaʻa fringing reef suggest genetic or environmental differences in coral resilience between sites. A reciprocal transplant experiment was conducted to determine if calcification (linear extension and dry skeletal weight) for dominant reef-building species, Montipora capitata and Porites compressa, varied between the two sites and whether or not parent colony or environmental factors were responsible for the differences. Despite the two sites representing distinct environmental conditions with significant differences between temperature, salinity, and aragonite saturation, M. capitata growth rates remained the same between sites and treatments. However, dry skeletal weight increases in P. compressa were significantly different between sites, but not across treatments, with linear mixed effects model results suggesting heterogeneity driven by environmental differences between sites and the parent colonies. These results provide evidence of resilience and acclimatization for M. capitata and P. compressa. Variability of resilience may be driven by local adaptations at a small, reef-level scale for P. compressa in Kāneʻohe Bay