Dione Swanson

2016

The status and extinction risk determinations leading to the final classification of 20 coral species as threatened under the U.S. Endangered Species Act (ESA) were based on extremely sparse species-level observational data of the species’ distributions, abundances, and vulnerabilities to a diverse range of threats. The process demonstrated that our collective ability to 1) quantitatively estimate coral population “stock” status, 2) answer fundamental questions about the status of coral populations, or 3) assess potential impacts of disturbance on threatened species, and even abundant species, is limited by inadequate field observations and insufficient analytical tools and assessment capacity. To address these needs for management of coral populations, a quantitative assessment should include occurrence, abundance (relative or total number of colonies), and spatial distribution in addition to metrics that provide strong demographic inference (e.g. life-history stage, size structure), as well as the influential environmental covariates. Collectively these parameters provide insight to the population status (including strong inference of demographic processes –recruitment, growth, survival), potential environmental factors that influence status, and how populations may respond to events such as disease, bleaching, or ocean acidification. Effective evaluation also requires determination of sampling effort required to achieve a desired level of precision of abundance estimates for a given species. Habitat use analysis of the spatially-explicit data from the recent stratified random survey (StRS) of coral populations in American Samoa (2015) can quantitatively address a suite of management needs for threatened coral species. Since a species’ habitat use has ties to population regulation (recruitment, growth, mortality) and persistence over time (i.e. productivity), spatial patterns of habitat use infer spatial variation in overall productivity. The most abundant ESA-listed species in these surveys was Isopora crateriformis. However, I. crateriformis was not consistently identified at the species-level across all surveys due to the potential similarity to I. cuneata. Post-cruise consultation with experts revealed that I. cuneata is not known to be in American Samoa, and the only other Isopora sp. (I. palifera) is considered rare. Thus, a quantitative assessment of the genus Isopora and three reference species that represent the range of abundance within American Samoa can be used to inform managers about: 1) the status of I. crateriformis, 2) environmental drivers that link spatial patterns of coral abundance and productivity, and 3) the survey effort required to improve assessment of ESA-listed species within the region.The goals of the proposed project include:Quantitative assessment that incorporates habitat use analysis of Isopora spp. Quantitative assessment of three reference species that represent three levels of abundance (abundant, common, and rare) to investigate variation in spatial patterns of abundance and productivity among species.Quantitatively identify environmental drivers that influence spatial patterns in coral abundance and productivity, compare variation in drivers’ effects among species, and provide a quantitative pathway to assess impacts on coral populations (e.g. disease, bleaching, and ocean acidification)Evaluate survey performance for Isopora spp. and three reference species to determine the level of sampling effort needed to improve precision of threatened species’ abundance estimates in American Samoa.

A series of tangible products are expected: Non-technical report that summarizes results from quantitative assessment of coral populations and multivariate statistical models will be disseminated to all relevant jurisdictional and Federal partners.Non-technical report that summarizes the performance evaluation of the recent survey effort (2015) and provides quantitative recommendations to all relevant jurisdictional and Federal partners for future surveys (levels of effort needed by site, stratum, island, and ecosystem).The suite of analyses developed for this project are particularly critical to determine the population status of ESA-listed coral species, the essential habitats and respective environmental drivers, and provide a quantitative foundation to design species-specific surveys if needed. Evaluation of species that are potentially threatened or endangered often lacks the quantitative data necessary to determine the status with confidence. Habitat use analysis of NCRMP benthic survey data can provide the quantitative information necessary to assess the status of coral populations (abundance, structure, and spatial distribution). The first non-technical report will provide managers with essential information needed to assess risk, develop mitigation strategies, and preserve resilient areas. The second non-technical report will focus on quantitative options for future surveys. Specifically, these results will improve quantitative assessment of Isopora crateriformis, identify important environmental drivers for Isopora and reference populations, provide realistic estimates of the survey effort required to obtain statistically robust abundance estimates for I. crateriformis and reference species.

• American Samoa

Other Domestic or Global Project

Closed

Completed

https://www.coris.noaa.gov/search/rest/find/document?searchText=projectNumber%3A31063%20OR%20projectTitle%3A"Linking%20spatial%20patterns%20of%20Isopora%20with%20environmental%20drivers%20to%20improve%20assessment%20of%20ESA-listed%20corals%20in%20American%20Samoa."&start=1&max=10&f=searchPage