Chapter 3 examines one piece of environmental management that needs to be addressed for deep-seabed mining: biodiversity assessment and monitoring. Multiple approaches are available to conduct biodiversity assessment and monitoring, such as morphology-based taxonomy and metabarcoding . The former involves an expert handpicking organisms out of an environmental sample and identifying them by eye or with the aid of a microscope. The latter involves chemical processing, molecular sequencing, and bio-informatics. Each of these methods are associated with scientific advantages and disadvantages, including how well they inform ecosystem services, and specific economic costs. In addition to discussing these scientific trade offs, Chapter 3 compares their cost-effectiveness in identifying deep-sea organisms, which is relevant to decision-makers when considering assessment and monitoring requirements. Another approach often employed in deep-sea research is the use of remotely-operated vehicles to survey and collect samples, including a wealth of imagery data. In the summer of 2015, Ocean Exploration Trust completed an expedition to explore the southern California borderlands, which included ROV dives at several methane seeps on the continental margin . Methane seeps are habitats where hydrocarbons and other fluids escape from the seafloor, fueling a biological community based on chemosynthesis . In a widely food-limited environment,indoor growers elevated primary production could significantly influence adjacent areas . Chapter 4 uses ROV dive videos from three methane seeps to demonstrate how deep-sea imagery can be used for characterization of ecosystem services. More specifically, Chapter 4 focuses on fisheries services and climate regulating services related to carbon, which have previously been documented at a California methane seep .
It provides the first detailed biological description of two methane seeps, and is the first application of an ecosystem services-based trait approach in the deep sea.Ecosystem services can also be generated by built ecosystems, such as natural storm water treatment systems . NTS are human-made installations that are designed to capture and treat storm water runoff using physical and biological processes . Coastal development and urbanization have altered water flows and introduced contaminants into runoff, which can cause flooding of infrastructure and pollution of local water . NTS provide a low-impact strategy to address these issues by slowing water flows, removing contaminants, and storing runoff for possible reuse . In southern California, where there is a discrepancy between water supply and demand, NTS are becoming more widespread . Chapter 5 reviews potential ecosystem services associated with NTS, such as targeted water infiltration and pollutant removal as well as non-targeted pollination, climate regulation, aesthetic value, and pests . Examples from Los Angeles County illustrate these ecosystem services and practical methods are suggested to begin quantifying and economically valuating them. Chapter 6 investigates one ecosystem service associated with NTS: climate regulation related to carbon. Vegetation within NTS, such as bio-filters and bio-swales, uptake atmospheric carbon dioxide through photosynthesis and can store it as biomass or in soil. Plant and soil respiration, the reverse process that releases carbon back into the atmosphere, is dependent on environmental characteristics such as soil moisture and soil temperature . Chapter 6 provides measurements of carbon fluxes over NTS, in comparison to other urban land uses in San Diego : grass lawns, horticultural gardens, and natural coastal sage scrub.
Data envelopment analysis is used to compare carbon efficiency, i.e. how well each system converts its given environmental characteristics into desirable carbon fluxes. This analysis incorporates both environmental inputs and outputs, which may be helpful when considering urban management strategies. The final chapter of this dissertation summarizes the lessons learned from applying an ecosystem services perspective in multiple systems using multiple approaches. It also provides recommendations for incorporating ecosystem services into environmental decision-making and management.Deep-seabed mining is an emerging industry that could begin commercial production in the near future. It has potential to alter habitats targeted for minerals through physical disturbance, removal of substrate, sediment resuspension and deposition, light, and noise . The International Seabed Authority , the body governing the international seabed and its resources , is tasked with developing rules, regulations, and policies, including those that will “[protect] the marine environment from harmful effects” and “[prevent] damage to the flora and fauna of the marine environment” . This obligation highlights the need for two tasks: establishing a baseline level of biodiversity for potentially impacted areas, and monitoring changes in biodiversity due to mining activities against that baseline. Deep-sea biodiversity supports a range of ecological functions and ecosystem services, such as fish catch, genetic resources for industrial and pharmaceutical products, carbon sequestration and storage, and nutrient cycling . The Clarion-Clipperton Fracture Zone is an abyssal plain area, ranging from approximately 3900-5500 m in depth, that hosts high densities of polymetallic nodules targeted for mining of copper, nickel, and cobalt. The CCZ has 30 exploration claims, each up to 75,000 square kilometers.
It also contains a wealth of biodiversity, some associated with the nodules themselves . Pilot studies and mining simulations have found little recovery of Pacific abyssal plain habitats post-disturbance within 26 years . Common megafaunal taxa in the CCZ include ophuiroids, xenophyphores, and corals, which are found in higher densities in the CCZ relative to other abyssal plain sites . Sediment macro- and meiofauna dominate eukaryotic species richness and densities on the abyssal plains , and include foraminifera, nematodes, polychaetes, isopods, and tanaids . While current ISA draft regulation for commercial exploitation of the Area acknowledges biodiversity as something to measure, the measurement approaches are not specified. Biodiversity can be measured in a variety of ways: number of species in an area, species absolute and relative densities, number of functional roles in a system and species interactions, genetic variation between and among populations, representation of phylogenetic lineages, and number of habitats and ecosystems . Current faunal bio-monitoring programs generally employ morphology-based taxonomy , which requires an expert to manually sort and identify hundreds to thousands of individual organisms. As a result, taxonomic studies in the CCZ require a lot of resources . The spatial heterogeneity of the CCZ biological community necessitates robust biodiversity assessment and monitoring . Large taxonomic gaps in deep-sea benthic communities still exist despite scientists working tirelessly to identify known species and describe new ones. As a result, MBT is limited to animal taxa that not only exhibit distinguishing morphological features , but also those for which expert taxonomists exist. Furthermore, this expertise can be especially difficult to find for deep-sea taxa and, as a result, much of the deep-sea environment remains undescribed . MBT is strongly limited by the amount of time and cost required to generate data, and the lack of taxonomic expertise that limits the breadth of biodiversity it can cover. This severely hampers scaling up both temporal and spatial resolution, and prevents timely adaptive management measures. Although MBT is necessary in order to describe new species , emerging molecular tools can serve to rapidly document biodiversity. Molecular techniques, such as metabarcoding and metagenomics,danish trolley provide a rapid alternative for biodiversity measurements in natural systems . Technical advances have increased our capacity to generate biodiversity data, by moving from DNA extracted from a single individual to environmental DNA obtained from an environmental sample in order to rapidly assess whole biological communities. Here, we focus on the application of metabarcoding: the sequencing of specific genes, used for taxonomic identification, in an environmental sample . A mix of both morphology-based and molecular-based methodologies are advocated to build robust and extended biodiversity inventories in the CCZ .
An example of a combined workflow couples morphological identification of individuals with DNA sequencing . While initially labor-intensive, this combined approach to taxonomy can facilitate later environmental assessment and monitoring by reducing the need for morphological identification as more species are described and sequenced. Additionally, a combined approach can promote standardization for data comparison among CCZ claims. For example, contractors measuring biodiversity within their own claims may be identifying the same species differently from other contractors. With a physical specimen associated with a genetic sequence, this issue could be more readily resolved even without a formal species description. Another example of a combined approach is initial genetic screening of large swaths of the CCZ to prioritize areas of interest for more detailed morphology work. It is likely that a combination of techniques is necessary in order to obtain scientifically robust data for environmental baseline and monitoring requirements set by UNCLOS and the ISA, such as those related to abundance and biomass, and genetic connectivity . This paper aims to evaluate scientific and economic trade offs between MBT and metabarcoding of small eukaryotes in the context of deep-sea biodiversity assessment and monitoring. Specifically, we discuss MBT and metabarcoding for evaluation of deep-seabed mining impacts in the CCZ, where interest in polymetallic nodules is high , small and rare taxa are dominant , and patchiness is substantial . We consider scientific trade offs between approaches in relation to environmental assessment and monitoring objectives, as well as how a combined approach can mitigate each method’s weaknesses. Decision networks are constructed for each methodology to highlight how decisions within each approach can affect scientific outcomes and economic costs. Lastly, we assess and compare direct and indirect costs associated with each methodology in a cost-effectiveness framework.Both MBT and metabarcoding techniques are framed here as a series of choices within a workflow that can influence both scientific outcomes and economic costs. We surveyed deep-sea experts and published protocols in order to determine the steps within each methodology, and how the choices within those steps affect scientific outcomes. In most cases, scientific questions and desired outcomes dictate how choices are made, creating a range of appropriate protocols so only general steps are listed in the results.Cost-effectiveness analysis is an economic approach that evaluates outcomes and their associated costs . An action or policy can be considered “cost effective” if it is the least costly to obtain a desired outcome, or it generates the best outcome given fixed resources. CEA differs from cost-benefit analysis because, rather than answering whether an action should be taken or not, it ranks strategies to maximize their efficiency . Posed with the question of how the ISA and contractors can meet environmental requirements, CEA can facilitate choosing which methods, or combination of methods, are most least-cost cost-effective. For each methodology, experts and published protocols provided estimates of the consumables used and number of work hours taken in order to generate taxonomic data. Total cost is the sum of consumable and labor costs. Fixed costs, such as laboratory equipment and bio-informatics pipelines, were not included in our analysis. Quantity of consumables were summed. Prices were taken directly from supplier websites, and are likely an overestimate because many research institutions receive discounted prices. Common suppliers in the U.S. were used: Fisher Scientific, VWR, and Qiagen, and prices were averaged among them. Labor costs came from best estimates of work hours .In our model, output is the number of “operational species” identified. “Operational species,” or proxies for species, are commonly used in biodiversity assessments because sampled deep-sea organisms are often new to science . MBT can employ morphospecies, individuals grouped together solely by morphology, whereas molecular methods use operational taxonomic units to distinguish species . Using operational species is less costly than describing every new species discovered, which involves writing a detailed morphological description and designating a holotype.Combining morphological and genetic operational species may circumvent the need for formal species descriptions and provide a standard unit of outcome that is relevant to both decision-making and our analysis. To approximate sampling regimes in the CCZ, we looked at a subset of published studies that attempt to characterize CCZ biodiversity of sediment eukaryotes using either MBT or molecular methods . Details from their sampling designs were extracted , as well as their relevant results . This information was used to make more appropriate comparisons between MBT and metabarcoding.Scientific trade offs should be considered while comparing MBT and metabarcoding, including what data are generated and information gained from their interpretation. These are summarized in Table 3.1 and discussed below. CCZ biodiversity is dominated by small and rare eukaryotes , which may favor taking a molecular approach to biodiversity assessments. However, although there is limited deep-sea taxonomic expertise, there is also little robust genetic information on CCZ fauna.