Defining Boundaries for Ecosystem-Based Management: A Multispecies Case Study of Marine Connectivity across the Hawaiian Archipelago (original) (raw)
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Determining the geographic scale at which to apply ecosystem-based management (EBM) has proven to be an obstacle for many marine conservation programs. Generalizations based on geographic proximity, taxonomy, or life history characteristics provide little predictive power in determining overall patterns of connectivity, and therefore offer little in terms of delineating boundaries for marine spatial management areas. Here, we provide a case study of 27 taxonomically and ecologically diverse species (including reef fishes, marine mammals, gastropods, echinoderms, cnidarians, crustaceans, and an elasmobranch) that reveal four concordant barriers to dispersal within the Hawaiian Archipelago which are not detected in single-species exemplar studies. We contend that this multispecies approach to determine concordant patterns of connectivity is an objective and logical way in which to define the minimum number of management units and that EBM in the Hawaiian Archipelago requires at least five spatially managed regions.
Hawaiian Islands Marine Ecosystem Case Study: Ecosystem- and Community-Based Management in Hawaii
Coastal Management, 2009
The Hawaiian Islands comprise a large and isolated archipelago that includes the largest reef area in the United States. Managing nearshore fisheries in this archipelago is a major challenge compounded by the difficulty of coordinating multiple agencies to provide governance across a broad series of islands with substantial social and political differences. There has been interest in, and progress toward, key elements of ecosystem-based management (EBM) in Hawaii, including a network of MPAs and community-based co-management. However, progress has been slow and largely driven by increased attention to the risks facing coral reef ecosystems, enabling both legislation and emergence of local engagement in fishery issues. Key elements of EBM in Hawaii include enhanced coordination among multiple agencies, establishment of place-based and community-based (or Hawaiian ahupua'a'-based) co-management, and acquisition of data on both the ecology of the nearshore system and the role of human impacts for use in management decisions. The development of community-based co-management and an MPA network along the western Kohala-Kona coast of the island of Hawaii (West Hawaii) illustrates a unique approach demonstrating an incremental approach toward EBM. Nonetheless, there are major challenges to scaling up the West Hawaii model to other islands within the state. These challenges include (1) the limited extent of community involvement, as well as legislative and administrative support, of communitybased co-management and MPAs, (2) the complexity of conflicts that develop on more populated islands with diverse stakeholders, (3) weak enforcement of fishing regulations, and (4) whether synergy among federal, state, and local governments, nongovernmental organizations, and the scientific community will be sustainable.
A distance-based multivariate control chart is a useful tool for ecological monitoring to detect changes in biological community resulting from natural or anthropogenic disturbances at permanent monitoring sites. It is based on a matrix of any distances or dissimilarities among observations obtained from species composition and abundance data, and bootstrapping techniques are used to set upper confidence bounds that trigger an alarm for further investigations. We extended the use of multivariate control charts to stratified random sampling and analyzed reef fish monitoring data collected annually on shallow (≤30 m) reefs across the Northwestern Hawaiian Islands (NWHI), part of the Papah¯ anaumoku¯ akea Marine National Monument. Fish assemblages in the NWHI were mostly stable, with exceptions in the south region (Nihoa, Mokumanamana and French Frigate Shoals) in 2012 and 2015 where changes in the assemblage structure exceeded the upper confidence bounds of multivariate control charts. However, these were due to changes in relative abundances of native species, and potentially related to the small numbers of survey sites and relatively low coral covers at the sites, particularly in 2015. The present study showed that multivariate control charts can be used to evaluate the status of biological communities in a very large protected area. Future monitoring of fish assemblages in the Papah¯ anaumoku¯ akea Marine National Monument should be accompanied by specific habitat or environmental variables that are related to potential threats to its shallow-water ecosystems. This should allow for more detailed investigations into potential causes and mechanisms of changes in fish assemblages when a multivariate control chart triggers an alarm.
Dominance of endemics in the reef fish assemblages of the Hawaiian Archipelago
Journal of Biogeography, 2020
Aim: Species ranges provide a valuable foundation for resolving biogeographical regions, evolutionary processes and extinction risks. To inform conservation priorities , here we develop the first bioregionalization based on reef fish abundance of the Hawaiian Archipelago, which spans nearly 10° of latitude across 2,400 km, including 8 high volcanic islands in the populated main Hawaiian Islands (MHI), and 10 low islands (atolls, shoals and islets) in the remote northwestern Hawaiian Islands (NWHI). Location: The Hawaiian Archipelago. Taxon: Fishes (276 taxa). Methods: We compiled 5,316 visual fish surveys at depths of 1-30 m from throughout the Hawaiian Archipelago. Geographical range (km 2) for each species was measured as extent of occurrence (EOO) and area of occurrence (AOO). PERMANOVA and PCO were used to investigate drivers of fish assemblage structure. Distance-based multivariate analyses were used to evaluate the relationship between fish assemblage structure and predictor variables including latitude, reef area, temperature, chlorophyll-a, wave energy and human population density. Results: Distinct fish assemblages exist in the MHI and NWHI, with two additional faunal breaks driven primarily by endemic species abundance. Latitude explained 37% of the variability in fish assemblages, with reef area accounting for an additional 9%. EOO showed a significant correlation with latitude. Endemics comprised 52%-55% of the numerical abundance at the northern end of the archipelago but only 17% on Hawai'i Island in the extreme south. Maximum size and activity regime (day vs. night) explained the most variation in the abundance of endemics. Main conclusions: The Hawaiian fish assemblages are strongly influenced by endemic species, affirming the archipelago as a biodiversity hotspot of high conservation value. The higher abundance of endemics in the NWHI may represent preadaptation to oceanic (oligotrophic) conditions. Resolution of distinct bioregions across the archipelago provides a better understanding of reef fish macroecology, with implications for management at the archipelago scale.
Aquatic Conservation: Marine and Freshwater Ecosystems, 2017
Large declines in reef fish populations in Hawai‘i have raised concerns about the sustainability of these resources, and the ecosystem as a whole. To help elucidate the reasons behind these declines, a comprehensive examination of reef fish assemblages was conducted across the entire 2500 km Hawaiian Archipelago. Twenty‐five datasets were compiled, representing >25 000 individual surveys conducted throughout Hawai‘i since 2000. To account for overall differences in survey methods, conversion factors were created to standardize among methods. Comparisons of major targeted resource species (N = 35) between the densely populated main (MHI) and remote north‐western Hawaiian Islands (NWHI) revealed that 40% of these species had biomass in the MHI below 25% of NWHI levels. In total, 54% of the species examined had biomass <50% of NWHI biomass. The moku or district was a basic unit of resource management in pre‐contact Hawai‘i and was used as a unit of spatial stratification for comp...
Diversity, 2020
The architectural complexity of coral-reef habitat plays an important role in determining the assemblage structure of reef fish. We investigated associations between the reef habitats and fish assemblages in the Northwestern Hawaiian Islands (NWHI) using in situ fish counts and data on habitat metrics and benthic community composition that were obtained from three-dimensional (3D) photogrammetric reconstructions of the surveyed sites. The structure of fish assemblage as a whole on the basis of Bray-Curtis dissimilarity, species richness and the abundances of herbivores and piscivores were associated with habitat metrics, with higher levels of architectural complexity generally supporting greater numbers of fish species and individuals. Benthic cover did not explain additional variation in these variables after the effects of habitat metrics were taken into account. Corallivorous fish was the only group that showed positive associations with both habitat metrics and benthic cover (Acropora and Pocillopora corals). The total fish abundance and the abundances of planktivores and invertivores did not show associations with either habitat metrics or benthic cover. This study suggests that an appropriate combination of habitat metrics can be used to account sufficiently for the effects of habitat architecture on fish assemblages in reef monitoring efforts in the NWHI.
Integrated island ecosystem ecology in Hawaii: spatial distribution of island biota: introduction
1975
This portion of the synthesis volume is being reproduced now because it is important that all synthesis volume contributors have these basic materials as they prepare their own contributions. Chapter 6, the subject matter of this report, follows the first five chapters that were contained in Technical Report 54 (Introductory Survey, Part I of the Synthesis Volume). It is expected that there will be some reworking of sections of this report as more data are analyzed and the integration needs of the entire synthesis part become more apparent. Chapter 6 is only the introduction to Part II. Additional material will include the altitudinal distribution of individual organism groups (Chap. 7) and their spatial integration along the Mauna Loa Transect (Chap. 8).
Marine Ecology Progress Series, 2004
The spatial distribution and magnitude of endemism in shallow-water (<18 m) reef fishes of the 10 Northwestern Hawaiian Islands (NWHI) are described in terms of occurrence, and numerical and biomass densities, using a series of diver-observation surveys conducted during September/October 2000. Based on species-presence in our surveys, we found endemism to be equal (20.6% using all available data) for fishes in the NWHI and the Main Hawaiian Islands (MHI; 20.9%). On average, percentage endemism was much higher based on the biomass (37%) and numerical densities (52%) of endemics, increased with latitude, and was especially pronounced at the 4 northernmost reefs that are the most ancient emergent geological features of the archipelago. Endemic reef fishes were appreciably smaller bodied than non-endemics within the NWHI. Median body size did not vary with latitude and longitude for either endemics or nonendemics, negating environmental effects. Reef fish populations at higher latitude reefs included larger proportions of young-of-year (YOY) recruits. YOY length frequencies did not differ for most species between northern and southern reefs, suggesting that a seasonal lag in spawning and recruitment at higher latitudes cannot explain the greater YOY densities observed there. Disproportionate recruitment at higher-latitude reefs may be related to better growth and survivorship after settlement onto reefs, higher levels of within-reef and regional reseeding at higher latitudes, or other factors. Resolution of these issues will be difficult, but it is profoundly important to the future siting of no-take Marine Protected Areas (MPAs) within the NWHI Coral Reef Ecosystem Reserve and to the rational conservation and management of reef fish resources throughout the Hawaiian Archipelago.
Coral Reefs, 2003
The relationships between fish assemblages, their associated habitat, and degree of protection from fishing were evaluated over a broad spatial scale throughout the main Hawaiian islands. Most fish assemblage characteristics showed positive responses to protection whether it was physical (e.g. habitat complexity), biological (e.g. coral cover growth forms), or human-induced (e.g. marine reserves). Fish biomass was lowest in areas of direct wave exposure and highest in areas partially sheltered from swells. Higher values for fish species richness, number of individuals, biomass, and diversity were observed in locations with higher substrate complexity. Areas completely protected from fishing had distinct fish assemblages with higher standing stock and diversity than areas where fishing was permitted or areas that were partially protected from fishing. Locations influenced by customary stewardship harbored fish biomass that was equal to or greater than that of no-take protected areas. Marine protected areas in the main Hawaiian islands with high habitat complexity, moderate wave disturbance, a high percentage of branching and/or lobate coral coupled with legal protection from fishing pressure had higher values for most fish assemblage characteristics.