Nearshore Habitat Restoration in Puget Sound

The marine waters of Puget Sound are dynamic and contain a wide diversity of organisms.  Professor Joel Elliott and his students are actively involved in the study of various aspects of Puget Sound marine life.  One of their projects is to examine the distribution and abundance of eelgrass in nearshore habitats.  Eelgrass (Zostera marina) beds are important components of marine ecosystems, acting as areas of high productivity, stabilizing sediment, and providing critical habitat for juvenile salmon and other marine organisms.  Worldwide, eelgrass beds are threatened by human activity, and a similar trend is occurring in Puget Sound.  Due to the importance of eelgrass beds as critical habitat for endangered salmon populations, government agencies, community groups, and environmental organizations are interested in conducting eelgrass restoration in local marine habitats.

Since 2001, Dr. Elliott and his students have been working in collaboration with local environmental organizations to monitor the distribution and abundance of eelgrass beds in the nearshore zone of Commencement Bay.  They use underwater video and GPS (Global Positioning Systems) technologies to map the locations of eelgrass beds and then analyze the data using GIS (Geographic Information Systems).  Historically, eelgrass habitat in Commencement Bay has been significantly reduced because of shoreline development and industrial activity.  In particular, more than 30 lumber mills operated on the Tacoma waterfront between 1869-1977, and Dr. Elliott and his students have found that there is a significant amount of wood waste buried in the nearshore sediments at some of these former mill sites.  The decomposition of this wood waste leads to high levels of hydrogen sulfide in the sediments, which is detrimental to the growth and survival of eelgrass (see Elliott, Spear, and Wyllie-Echeverria 2006), and most other marine organisms.  The bacterial mats discovered in these areas of high hydrogen sulfide appear to be similar to those associated with deep sea hydrothermal vents, and Dr. Elliott and his students are collaborating with microbiology professor Mark Martin to characterize the microbial communities found in these areas.

Professor Elliott is now working with other researchers, government agencies, community groups, and environmental organizations to develop effective protocols for restoring eelgrass to shorelines affected by decomposing wood waste and other human activities.  This work will provide insights into successfully dealing with this newly discovered environmental problem affecting near shore habitat, and should lead to restoration protocols that can be adopted at a variety of sites in Puget Sound.

The Effect of Introduced Mussels on Intertidal Communities

The introduction of non-indigenous species into marine habitats has had dramatic impacts on the viability of native species and the functioning of food webs.  Introduced species are considered to be one of the important environmental threats to the Puget Sound ecosystem.  Dr. Elliott has been collaborating with biology professor Peter Wimberger, along with more than 20 of Puget Sound’s biology students, to examine the effects of an introduced mussel (Mytilus galloprovincialis) on intertidal communities in Puget Sound.  The main goal of their research is to determine the factors influencing the distribution and abundance of the introduced mussel, the native mussel M. trossulus, and their hybrids in Puget Sound.  Studies have been conducted to determine the differences in size, shape, and genotypes among the different mussel species in various habitats of Puget Sound (see Elliott, Holmes, Chambers, Leon, and Wimberger 2008).  Other studies have examined the growth and survival rates of the different mussel species in relation to habitat type and competition (see Rensel, Elliott, and Wimberger 2005). Mussels are important ecosystem engineers in Puget Sound, providing habitat for other marine organisms, and Dr. Elliott and his students have examined the biodiversity of invertebrates living on mussels.  Ongoing studies include the effects of predation by sea stars, crabs, and birds on the relative survival of the two mussel species, and the effects of bird predation on sea stars.  The ultimate goal of this research is to determine how the introduced mussel is affecting intertidal communities and food webs in Puget Sound, and to predict what changes may occur in the future.

Relevant Scientific Publications with student researchers (*)

Elliott, J.K., K. Holmes*, R. Chambers*, K. Leon*, and P. Wimberger. 2008. Differences in morphology and habitat use among the native mussel Mytilus trossulus, the non-native M. galloprovincialis, and their hybrids in Puget Sound, WA. Marine Biology: 156:39–53.

Elliott, J.K., *Spear E., and S. Wyllie-Echeverria. 2006. Mats of Beggiatoa bacteria reveal that organic pollution from lumber mills inhibits growth of Zostera marina. Marine Ecology. 27: 372-380.

Rensel* M., J.K. Elliott, and P. Wimberger. 2005. Will the introduced mussel Mytilus galloprovincialis outcompete the native mussel M. trossulus in Puget Sound?  A study of relative survival and growth rates among different habitats. Proceedings of the Puget Sound Georgia Basin Conference, Seattle, 2005.