Alaska and Pacific Northwest Research
Several research projects involving marine derived nutrients (dead salmon) and the community responses of stream insects to this subsidy, as well as the effects of clear-cut logging in headwater streams is discussed in the following research projects.
1. The Role of Marine Nutrients from Salmon in Managed U.S. forests (USDA NRI) (ongoing). ;Goals are to determine how forest management affects the retention of salmon nutrients in stream ecosystems, and the consequences of SDN retention for stream ecosystem processes including salmon production. (Tongass National Forest, Alaska). (Cooperators: Co-PI with Lamberti, Tank, Chaloner, Edwards (Eric Benbow involved with Merritt on this project)
2. The Role of Macroinvertebrates in the growth of juvenile Coho salmon in the Copper River Delta, Cordova, Alaska (USFS Coop. Agreement) (ongoing)---Goals are an assessment of the macroinvertebrate community structure in streams of the Copper River Delta, Alaska, and associated dietary use by juvenile salmonids. (Cooperators: Todd White (grad student), Gordie Reeves, Ken Cummins, Marty Berg, G. Lamberti)
3. Benthic Invertebrate Community structure is influenced by forest succession after clear-cut logging in southeastern Alaska (USFS, Prince of Whales, Alaska) (1998-2000)-- Benthos in streams of previously harvested areas resulted in increased richness, densities and biomass relative to old growth types, particularly in young growth stands with a red alder-dominated riparian canopy. Woody debris and gravel habitats supported a combination of higher densities and biomass of invertebrates than cobble habitats.
4. Macroinvertebrate communities associated with early and late stage decay alder and conifer wood in southeast Alaska headwater streams (USFS, Prince of Whales Alaska)(2001-2002). Results of this study showed that the presence of riparian alder along southeast Alaskan headwater streams appeared to influence stream benthic macroinvertebrate densities associated with wood substrates. (Cooperators: R.K Kimbirauskas (grad student), M.S. Wipfli, and P. Hennon)
5. Influence of marine-derived nutrients from spawning salmon on aquatic insect communities in southeast Alaskan streams (USDA, USFS-Juneau, Prince of Whales, Alaska) (2000-2003). The objective of this study was to evaluate the influence of the nutrient transfer system between anadromous salmon and aquatic insect communities across multiple, natural stream systems. Between 2000 and 2002 we sampled seven streams in southeast Alaska, seasonally. Of the seven study streams four received large annual salmon runs (high-run streams), and three were no-run streams. All the streams selected had a natural waterfall barrier to salmon, providing an upstream control reach for each study stream. Insect density, biomass, richness, diversity and functional feeding groups were analyzed before, during and after the fall salmon run in each stream section (i.e. above and below the barrier) of the seven study streams between 2001 and 2002. Results showed that diversity and richness were similar across stream sections and run size within each period, except for during the run when both were significantly lower in downstream sections of high-run streams. Functional feeding group patterns showed higher abundance and biomass of collector-gatherers and shredders during the post spawning, carcass decomposition period. High-run streams had upstream sections with greater abundance and biomass of mayflies (dominated by Baetidae,Heptageniidae and Ephemerellidae) during the run, and downstream sections with greater abundance and biomass of Dipterans (dominated by Chironomidae). This study suggests that the often published positive relationship between MDN and stream insect abundance and biomass may only exist for certain taxa, primarily Chironomid midges. (Cooperators: J. Lessard (grad student), G. Lamberti, D. Chaloner, J. Tank, M. Wipfli, P. Ostrom, M. Berg)
6. Macroinvertebrate communities of the hyporheic zone in Alaskan streams (USFS) (2004-2006). We have been studying the hyporheic macroinvertebrate communities among stream types of southeastern Alaska. The primary objectives of this study are to: 1) determine the macroinvertebrate community in hyporheic habitats among glacial, non-glacial, large clearwater, and muskeg outlet streams; 2) determine if there is a longitudinal species gradient extending from near the stream channel outwards; 3) estimate standing stock biomass and secondary production of predominate insect species associated with the hyporheos of the above stream types; and 4) determine if the hyporheos acts as a refuge during salmon redding, and if possible, during extended spate events. (Cooperators: Matt Wesener (grad student), Rick Edwards)
7. Headwater riparian invertebrate communities associated with red alder and conifer wood and leaf litter in southeastern Alaska (USFS) (2000-2001)---We examined how management of young upland forests in southeastern Alaska affect riparian invertebrate taxa richness, density, and biomass, in turn, potentially influencing food abundance for fish and wildlife. Southeastern Alaska forests are dominated by coniferous trees including Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and mixed stands with red cedar (Thuja plicata Donn.). Red alder (Alnus rubra Bong.) is hypothesized to influence the productivity of young-growth conifer forests and through forest management may provide increased riparian invertebrate abundance. To compare and contrast invertebrate densities between coniferous and alder riparian habitats, leaf litter and wood debris (early and late decay classes) samples were collected along eleven headwater streams on Prince of Wales Island, Alaska, during the summers of 2000 and 2001. Members of Acarina (mites) and Collembola (springtails) were the most abundant taxa collected in leaf litter with alder litter having significantly higher mean taxa richness than conifer litter. Members of Acarina were the most abundant group collected on wood debris and alder wood had significantly higher mean taxa richness and biomass than conifer wood. Alder wood debris in more advanced decay stages had the highest mean taxa richness and biomass, compared to other wood types, while conifer late decay wood debris had the highest densities of invertebrates. The inclusion of alder in young-growth conifer forests can benefit forest ecosystems by enhancing taxa richness and biomass of riparian forest invertebrates (Cooperators: Christian LeSage (grad student), Mark Wipfli)
8. The influence of increased light and alternate nutrient sources on growth of juvenile salmonids and their supporting food webs (Calif. Coop. Fish. Unit, Humboldt State University) (2004-2007). Goals are to provide information relevant to developing a successful adaptive management program for salmonid maintenance, recovery, or enhancement, through an evaluation of manipulations intended to increase juvenile salmonid growth. Through an approach combining field and laboratory experiments, specific objectives are to evaluate the relative effects of increased light, nutrient enhancement from salmon carcasses, and nutrient enhancement from conifer and alder litter on: a) growth of juvenile salmonids; and b) structure of the invertebrate food web pathways that support salmonid production. (Cooperators: Osvaldo Hernandez (grad student), Peggy Wilzbach, Ken Cummins)
9. An assessment of the macroinvertebrate community structure in streams of the Copper River Delta, Alaska, and associated dietary use by juvenile salmonids (2005-2008). During the summers of 2004-2006, a study of the macroinvertebrate communities and associated dietary preferences of juvenile salmonids inhabiting streams in the vicinity of Cordova, AK in the Chugach National Forest was initiated under a cooperative agreement between the Cordova, Alaska, Ranger District of the USFS, and Michigan State University. Analysis is underway. (Cooperators: Todd White (grad student), Ken Cummins, Gordie Reeves, Deyna Kuntzsch, Dirk Lang)
10. The role of marine nutrients from salmon in managed U. S. forests (2005-2009). Prince of Wales Island (POW) is located in Southeast Alaska and is one of the last regions along the Pacific coast which still supports large runs of anadromous salmon (Oncorhynchus spp.). Pacific salmon can act as both a source of marine-derived nutrients to the typically oligotrophic streams of southeast Alaska and as sources of disturbance throughout their upstream migration and redd construction. Significant anthropogenic impacts in the form of clear-cut logging have altered local stream channel morphological complexity by reducing large woody allochthonous inputs, potentially threatening salmon habitat and the availability of invertebrate prey. An area of this research focuses on the impacts of salmon disturbance and timber harvest effects on the distribution and integrity of stream insects. One of the least studied habitats in southeast Alaska and elsewhere is backwater pools which can act as a source of habitat refugia for main-channel taxa during disturbance events. Backwater pools may also sustain unique sensitive taxa such as case-building caddisflies not found elsewhere in lotic systems, elucidating the importance of sampling these habitats for bioassessment protocols. Timber harvest may reduce the availability of refuge habitats which may be needed for macroinvertebrate survival. Understanding seasonal dynamics of benthic communities and how humans affect these systems have far reaching implications in the effort to sustain the integrity of our watersheds. (Cooperators: Emily Campbell (grad student), Gary Lamberti, Scott Tiegs, Eric Benbow, John Hudson, Janine Rueegg, Peter Levi, Dominic Chaloner, Jennifer Tank)
11. Invertebrate Communities Associated with Aquatic Vegetation in Ponds of the Copper River Delta, Alaska (2007-present). Ponds on the Copper River Delta are important habitat for fish and summer habitats for a variety of waterfowl, including Dusky Canada geese. There is growing concern about the persistence of these ponds on the Delta, particularly the western portion that was uplifted by the 1964 earthquake. This shifted the West Delta from a tidally influenced marsh to a perched freshwater system. Since that time, the ponds appear to have undergone changes with regards to vegetative composition and many are shrinking in size. There are concerns about potential changes in the ecological quality of the ponds related to this ongoing vegetative succession. Of particular concern is the future of waterfowl production on the Delta. A portion of the study of the Delta ponds is focused on the invertebrate communities associated with the major vascular aquatic plant bed types as an important component of the food base for fish and waterfowl rearing in the ponds. Specific associations between invertebrates and each of the major plant bed types are under study. Because the plant beds are largely mono-specific and the invertebrate community associations appear to be reliably predictable, it should be possible to develop a pond-specific conceptual model relating plant bed cover, associated invertebrates, and potential food for fish and waterfowl. (Cooperators: Derek Busch (grad student), Ken Cummins, Marty Berg, Gary Lamberti, Gordie Reeves, Deyna Kuntzsch, Paul Meyers)
Publications from Alaska projects:
Lessard, J. L., R. W. Merritt and K. W. Cummins. 2003. Spring growth of caddisflies (Trichoptera: Limnephilidae) in response to marine-derived nutrients and food type in a Southeastern Alaskan stream. Annales de Limnologie 39: 3-14.
D. T. Chaloner, G. A. Lamberti, R. W. Merritt, N. L. Mitchell, P. H. Ostrom, and M. S. Wipfli. 2004. Variation in responses to spawning Pacific salmon among three south-eastern Alaskan streams. Freshwat. Biol. 587-599.
Lessard, J.L. 2004. Influence of marine-derived nutrients from salmon on stream macroinvertebrate communities in southeast Alaska. Ph. D. Dissertation, Michigan State University, East Lansing, MI.
Hernandez, O., R. W. Merritt, and M. S. Wipfli. 2005. Benthic invertebrate community structure is influenced by forest succession after clear-cut logging in southeastern Alaska. Hydrobiologia 533: 45-59.
Lessard, J. L., and R. W. Merritt. 2006. Influence of marine-derived nutrients from spawning salmon on aquatic insect communities in southeast Alaskan streams. Oikos 113: 334-343.
LeSage, C., R. W. Merritt, and M. S. Wipfli. 2006. Headwater riparian invertebrate communities associated with red alder and conifer wood and leaf litter in southeastern Alaska. Northwest Science 79:218-232
Kimbirauskas, R., R. W. Merritt, M. S. Wipfli, and P. Hennon 2008. Macroinvertebrate communities associated with early and late stage decay alder and conifer wood in southeast Alaska headwater streams. Pan Pacific Entomologist (in press)
Tiegs, S.D., D.T. Chaloner, P. Levi, J. Rueegg, J.L. Tank and G.A. Lamberti. 2008. Timber harvest transforms ecological roles of salmon in Southeast Alaska rain forest streams. Ecological Applications/ 18:4-11.
Lessard, J. L., R.W. Merritt, and M.B. Berg. 2008. Secondary production of mayflies and midges in response to spawning salmon in Alaskan streams: The importance of disturbance in marine-derived nutrient theory. JNABS (submitted)