3-5/3-6) Kissinger, Beavers, Salmonoids

explain the basics of kissinger experiment - otolith, conclusions?

inner ears bones, laid out like tree rings (outwards growth), calcium/strontium stays there after being absorbed
strontium is higher in brackish water
able to determine life history from the strontium

freshwater fish were less able to regulate the salt in their bodies compared to brackish fish
drinking rate increased as fish moved to saltwater areas

explain the choice experiment, hypothesis, conclusions?

fish choose which side they want to be in, then the salinity will increase or decrease and they can choose again
hypothesis: brackish fish will prefer higher salinity
results: brackish preferred less salinity, freshwater has no preference because they lack receptors to determine salinity

what makes beavers special

semi-aquatic mammals, webbed feet, large paddle tail (used for swimming, packing mud on dam, warnings), unique teeth to cut trees, dams to store water and lodges as shelter

what ecosystem services do beavers provide?

mitigate flood and drought, dams act like speed bumps (reduce stream velocity by 81%, decrease stream power (amount of energy stream exerts on sides and bottom by 92%), allow water to filter into the ground (replenish groundwater

stream with beaver is less likely to have severe fire and drought consequences, and has better groundwater storage

what are challenges beavers cause? what can we do to increase beaver occurrence?

cause lots of change on landscape, roads washed out, removing trees

culver covers, pond levelers

salmonoid experiment, details on species, results

bull trout: stream, longest lived, more piscivorous with increase in size, fall spawning. downstream range contraction/extirpation
rainbow trout: stream, most tolerant of temp increases, spring spawning. range contraction, reduction in abundance in core and periphery
cutthroat trout: stream, spring spawing. downstream range contraction and extirpation, low abundance in higher elevation

what are the 4 major threats we discussed

habitat loss, non-native species, climate change, angling/hunting

habitat loss: dams, forestry, water extraction all impact sedimentation and nutrient loading
non-native species: can cause competition and hybridization (gene diversity lost), pure species get diluted especially with fish that have been stocked
climate change: correct water temp and levels are needed

which of the 4 major threats were most severe for each of the three species

rainbow trout: non-native species; competition and hybridization, heavily stocked non-native fish in headwater, hard to remove those species
bull trout: climate change; requires cold water, limits downstream distribution, and non-native species; competition and hybridization with brook trout
cutthroat trout: non-native species; competition and hybridization

same threats will impact species differently, mainly due to differences in biology.