Prince Willam Sound Reef Ball Projects
Marion Hobbs is designing a small breakwater north of Juneau to protect a new dock facility at his property. He and NMFS wish to incorporate reefball technology into the design so the typical riprap structure can offer more habitat for fish and marine invertebrates. The breakwater would be located on an existing bedrock outcrop that currently support typical marine flora and fauna, with a sandy slope to the south and a rock wall to the northwest. The top of the breakwater would be at MHW. There would be a gap at the shore to allow for inshore migration of juvenile salmon, predominantly chum, that spawn in Yankee Creek very near to the dock and breakwater. The site has long been used as a recreational diving destination due to the abundant life on the rock wall. The sandy cove supports very little marine life except some flatfish, snake prickle backs, and anemones. Both Marion and I are active commercial and scientific divers respectively, and would be able to monitor the recolonization of reefball structures placed immediately adjacent to the breakwater. Southeast Alaska is a unique ecotone, with a high tidal range (-4.4' to 19.7'), low salinities typical of the inside passage, fluctuating visibility that is often very low, fast currents and an abundance of marine life. We seek to enhance the macro algal growth particularly of /Laminaria/ spp. that serves as herring spawning substrate and to provide an improved habitat over riprap for marine life in general. Note: Project accepted into Reefs Around the World Grant Program 2/2006
In spring 2006, NMFS will install Alaska?s first artificial reef near Whittier in western Prince William Sound (PWS). The purpose of this pilot project is to evaluate the reef?s potential as a fish habitat restoration tool in sub-Arctic marine waters. Alaska Marine Lines will install the sphere-shaped Reef Balls in accordance with a mitigation settlement. The result will be a reef of 90 Reef Balls deployed in three paired patches on a declining slope (15-20m depth) over mixed soft and hard sediment substrates (Fig1). Three natural rocky reefs in the project area will be monitored as a control. The study is designed to assess the effectiveness of artificial reef structures in restoring natural fish habitat. This study has the following objectives:
(1) document the marine community at the artificial reef a. describe spatially and temporally the plant and invertebrate assemblages b. document fish species diversity and abundance c.determine if marine communities vary by reef structure (2) assess if artificial reef communities enhance the immediate marine environment (3) assess artificial reefs as a fish habitat restoration tool
In addressing these objectives, two hypotheses will be tested:
H1. Fish habitat is enhanced after deployment of artificial reefs; fish diversity and abundance at artificial reef sites is increased in comparison to natural hard bottom habitat.
H2. Artificial reefs mimic the ecological structure and function of natural reefs such as rock outcroppings.
The study will rely on surveys using scuba diving, underwater camera, hook and line, and fish traps. Sampling methodologies stem from previous work on AR (Powers et. al. 2003, Conley et. al. 2000). Intensive monitoring will be conducted in the first 2 years of the project to effectively describe colonization time of objective (1) a. and b. After 2 years, monitoring will be limited to quarterly scuba dives and monthly fish traps to fully address objective (1) c., (2) and (3). The project will be conducted as a cooperative effort between NMFS HCD (Anchorage field office), the Prince William Sound Science Center (PWSCC), Cordova, Alaska; Dauphin Island Sea Lab, University of South Alabama; the NOAA Restoration Center; and the USFWS (Anchorage field office). PWS is an important site for commercial, subsistence, and sport fish harvest, as well as a port destination for oil tankers, cargo vessels, cruise ships, and recreational vessels. As economic growth and development continues in communities along the PWS the ability of fisheries managers to restore damaged and stressed fish habitat may be vital to a sustainable fishery. Marine coastal habitat is altered by a variety of development activities such as harbor development, dredge and fill operations, sheet-pile dock structures, and log transfer facilities. These development activities alter the function of pristine marine coastal habitats, principally by the removal, alteration or elimination of existing living habitat structure, including rocky reefs and aquatic vegetation. A study of the efficacy of artificial reefs to restore natural fish habitat loss will provide knowledge and direction for management of future restoration efforts in Alaskan coastal waters. To date development projects in Valdez, False Pass and Kodiak have shown interest in using artificial reefs as mitigation. Knowledge about the effectiveness of artificial reefs in providing fish habitat is necessary to evaluate these proposals and is currently unavailable. This project represents the only known research on use of artificial reefs in Alaskan waters.
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