ECOSYSTEMS MANAGEMENT STUDIES

Ecosystem management of the NWHI Marine National Monument

Rob J. Toonen, Kim A. Selkoe, and Ben S. Halpern

During the last quarter, we have focused primarily on our threat analysis project. As with any natural resource management situation, the degree and nature of human impacts on the NWHI ecosystem must be determined so that the worst of these can be regulated or mitigated. The need to understand the effects of human activities on the NWHI ecosystem is particularly critical at this time as regulations and management plans are currently being drafted for the NWHIMNM. While exhaustive lists of anthropogenic threats to the NWHI have been generated in the past (e.g., Maragos and Gulko 2002, Friedlander et al. 2005), understanding how and why those anthropogenic activities threaten the ecosystem has not been systematically addressed. The goals of this project are: (1) to understand which anthropogenic threats have had the greatest and least impact on the NWHI ecosystem; (2) to systematically compare the way in which each threat impacts the NWHI with five metrics; (3) to understand the different vulnerabilities of each habitat in the NWHI (e.g., lagoon, intertidal or deep banks) to each threat; and (4) identify which threats and habitats are poorly understood and require further study.

Our approach is based on surveying expert opinion and was developed in a previous study (Halpern et al. 2006) that sought to assess all anthropogenic threats to marine ecosystems on a global scale. Twenty-five academic, state, federal and NGO scientists with a mean of 391 days spent working in the NWHI completed the survey between February and May 2006. We have completed multiple analyses of the data and have written up two manuscripts for publication: a shorter one focused on the management and policy implications of our results; and a longer one focused on presenting the details of our methodology and analyses which is geared toward local natural resource managers and those in other areas of the world that may want to adopt our approach for their region. We will submit both manuscripts within the next few weeks.

Figure 1. Relative ranking of threats by the 5-factor vulnerability score (possible values range 0-4), based on pre-Monument conditions in the NWHI. Threats generated on a local scale (within the NWHI) are coded blue; light blue identifies threats that have been eliminated by the new Monument status; red = threats with a global scale source; gold = Pacific-wide. (Click on the image to open a larger version.)

The composite scoring developed using these data shows that the ecological status of the MHI is poor compared to the NWHI. A growing body of information demonstrates that the reefs of the NWHI are an integral component of the Hawaiian Archipelago ecosystem and are an extremely valuable ecological resource. Thus the proper management of the NWHI is important to the ecological vitality of the Hawaiian Archipelago as a whole. The NWHI should not be viewed as a separate entity from the MHI because the two areas are clearly interdependent. The migration of turtles from feeding grounds in the MHI to nesting grounds in the NWHI provides an excellent example of the interdependence of the two areas. Movement of large fish and endangered Hawaiian monk seals provide other examples. The fact that the same species of fish, corals and other marine organisms occur along the entire Archipelago with high rates of endemism provides evidence that the NWHI and the MHI represent a single ecosystem with a long evolutionary history.

Our initial findings on the vulnerability of the NWHI to different anthropogenic threats are presented in Figure 1. Effects of global climate change, such as sea level rise and sea temperature rise, threaten to have the most profound and widespread impacts on the ecosystems of the NWHI. Marine debris and associated ghost fishing — threats caused by a handful of Pacific-wide human activities — rank a close second.

The greatest locally-generated threats are posed by alien species invasions and ship groundings, both of which result from ship-based human visitation to the NWHI. Coastal engineering and runoff of pollutants, land-based threats generated by past military use of certain areas of the NWHI, were also identified as significant threats. In contrast, fishing, diving, and research scored relatively low presumably because they occur on much smaller scales and impact only few members of the marine communities with fast recovery times. These results have important implications for the management and funding priorities of the new Marine National Monument.

The lagoon/back/patch reef ecozone was identified as the most vulnerable environment, followed by the reef crest and slope, while the pelagic zone appears to be the least vulnerable to the present suite of threats. By asking respondents to indicate the certainty, or depth of knowledge, with which they estimated the vulnerability of ecozones to threats, we identified where knowledge gaps exist. Scientists had highest uncertainty in the way that climate change factors (increasing ultraviolet radiation, seawater acidification, rising sea level and sea temperature) affect the ecosystem. The effects of ship-based waste and land-based runoff are also poorly understood, and algal beds are the most poorly studied of the ecozones.

Figure 2. Bleaching will increase as sea temperature increases due to global climate change in the coming years. Photo shows Pocillopora meandrina (bleached), with initial overgrowth by turf algae in the centralpatch reef of Kure Atoll, Sept. 2002. Photo by J. Kenyon, reproduced from Friedlander et al. 2005. (Click on the image to open a larger version.)

Our next goal is to build a map of all anthropogenic impacts to the NWHI. This map will provide a strong visual impact of how threats are distributed across the area, and where the most and least impacted areas are. It will also be a useful tool for managers in setting use and management priorities for different areas, and provide a data repository that allows these datasets to be easily accessed and utilized. We have begun to identify and track down appropriate datasets for 18 principle threats from researchers around the world. We will work closely with Erik Franklin to create an interactive, web-based map using Arc GIS software tools.

In terms of our other ecosystem management project, modeling patterns of connectivity within and among the main islands and NWHI, we have primarily focused on gathering parameter values for species, some of which have only recently become available with recent publications. We have focused on lobster and coral life history, reproduction and demographic information. We have also continued refining our design of the population array based on updated habitat maps. Now that the threat analysis is wrapping up, we will spend more time doing preliminary model runs in the next few months.

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