• Ecological effects of spawning salmon on several southcentral Alaskan streams

      Piorkowski, Robert Joseph (1995)
      The ecological effects of salmon (Oncorhynchus spp.) carcasses on southcentral Alaskan streams were studied by: (1) observing salmon carcass decomposition and use; (2) comparing the macroinvertebrate community structure of streams receiving different inputs of salmon carcasses; and (3) quantifying the amount of marine-derived nitrogen (MDN) entering stream food webs using stable-isotope analysis. Abiotic mechanisms, such as large woody debris and the slow waters of stream margins and eddies were important in initial retention of salmon carcasses. Once entrained, carcasses decayed rapidly due to intense microbial processing. Stream insects and fishes were observed consuming carcasses, eggs, and smolts. Macroinvertebrate communities in streams receiving runs of salmon or in lake outlet streams were more diverse taxonomically. One functional feeding group, filterers (including net-spinning caddisflies (Hydropsychidae) uncommon in Alaska), increased in relative abundance. Although many other taxa also responded positively to enrichment, some taxa responded negatively. A significant difference existed in $\partial\sp{15}$N values between MDN and terrestrial sources but natural dissolved inorganic nitrogen contributions to stream food webs ($\approx$90-95% of total N) from groundwater generally overwhelmed the marine signal ($\approx$5-10% of total N). $\partial\sp{15}$N values generally suggested that some MDN ($\approx$15% of total N) entered into food webs after its incorporation into algal biomass but values for certain macroinvertebrate taxa (Arctopsyche and Plumiperla), salmon fry (Oncorhynchus spp.) grayling (Thymallus arcticus), rainbow trout (O. mykiss) and American dippers (Cinclus mexicanus) suggest these biota directly consume substantial amounts (40%-90%) of salmon protein. $\partial\sp{15}$N values in individual macroinvertebrate taxa usually cycled seasonally. All three elements of this investigation support the hypothesis that salmon carcasses can be important in structuring aquatic food webs.
    • Glycerol Metabolism And Other Biochemical Features Associated With Overwintering In The Adult Insect Pterostichus Brevicornis (Carabidae)

      Arvey, William Dale; Miller, Keith; Irving, Laurence; Behrisch, Hans W.; Smith, Ronald; Williams, Darrell (1974)
    • Survey Of Bombus Species (Hymenoptera: Apidae) Near Agricultural Lands In Interior Alaska

      Pampell, Rehanon; Holloway, Patricia; Knight, Charles; Sikes, Derek; Pantoja, Alberto (2010)
      Major world pollinators include bees, beetles, flies, butterflies, birds and bats, all of which help pollinate over 75% of Earth's flowering plant species and nearly 75% of the crops. In arctic and subarctic regions, bumble bees are considered important pollinators; however, immediate concerns involving climate change, colony collapse disorders in honey bees, and lack of faunistic insect studies in Alaska emphasize the need to study bumble bees in interior Alaska. I identified seventeen species of bumble bees from three localities: Delta Junction, Fairbanks, and Palmer, Alaska. Not all species were recovered from all localities and species richness and relative abundance varied by years. Delta Junction displayed the highest relative bumble bee abundance representing approximately 50% of the overall total of bumble bees collected during the two year study. Overall, the most common bumble bees near agricultural lands were B. centralis, B. frigidus , B. jonellus, B. melanopygus, B. mixtus, and B. occidentalis. Their populations and local diversity were highly variable from year to year. A species believed to be in decline in the Pacific North West states, B. occidentalis , was collected in relative abundance up to 13.5%; this species was collected from the three sites studied. Preliminary data indicates that bumble bees were found to be infected by Nosema and nematodes with infection rates up to 12.5 and 16.7% for Nosema and nematodes respectively. Of the eight species infected by parasites, B. occidentalis displayed the highest Nosema infection, while B. centralis was the species with the highest infection of nematodes.