Stream order increases when
two streams of the same order join to form a larger stream
Factors affecting fish distribution
1) temperature
2) Gradient
3) Fluctuation in flow
4) Habitat complexity
How does temperature affect fish distribution
- Warm water (24-26 C) leads to bass, catfish, minnows
- Cold water leads to trout, sculpins
How does gradient (meters drop per km) affect fish distribution
- affects velocity and substrate
- affects daily and seasonal temp
- at lower reaches, converges to a lake-like habitat
headwaters characteristics
- shaded
- production/respiraction less than 1.0
- Allochtonous carbon
mid-reaches characteristics
- more open, sunlight
- shallow, light reaches bottom
- Autochtonous carbon
- production/respiration >1
Lower reaches characteristics
- open, but deep, turbid
- less light to bottom
- more like a lake
- production/respiration < 1
increasing depth provides:
new niches (more habitat complexity so species richness will increase
Objectives of the owego creek study
-evaluate fish community change in upper creek between 1963 and 2003-04
Extripations from owego creek study
- Stoneroller
- redside dace
- Swallowtail shiner
Apparent declines from owego study
- Common shiner
- spottail shiner
- shield darter
- nourthern hog sucker
- white sucker
Why may there have been declines and extraptations of fish in the owego creek
- all 6 reside in the midwaters and can be seen by predators easily
- predator may be the brown trout (from stocking waters)
Why did new fish arrive at owego creek
- these species are orignially from the allegany basin and are expanding their ranges into the owego basin
- greenside darter, banded darter, mimic shiner
Conclusions from owego creek study
- Upper reaches of 3rd order show marked changes with extripations and new invasions
- Trout stocking of 12” browns may be primary cause of changes in minnow population
- Sticklebacks have replaced banded killifish, possibly due to the expansion of rockbass distribution (due to increase in water temp)
Effects of sediment on fish
- spawning disruption
- reduced larval survival, reproduction
- lower foraging efficiency
evidence of spawning disruption from sediment effects
-increased sediment leads to decreased spawning frequency, delayed spawning, and decrease in proportion of ripe eggs
evidence of reduced larval survival and reproduction due to an increase of sediment
- decrease yoy growth rate
- increase in stress enzyme lvl
- decreased spawning success
- increase in gill damage
evidence of lower foraging efficiency due to an increase of sediment
-increase in turbidity leads to a decrease in reactive distance and capture success
what fish is an example of an ulimate cosmopolitan fish
- bluegill sunfish
- adapts wherever introduced
Field evidence for land use effects of fish
1) loss of relatively specialized species
2) spread or persistence of generalized species
3) Faunal homogenization
Increase in deforestation and buildings =
-fewer endemic species
more cosmopolitan species
-species richness increased with land use intensity
How faunas become homogenized
1) Transportation and invasion by non-indigenous spp
2) invaders make the habitat less favorable for endemics (disturbance)
3) gradual replacement of local endemics by widespread generalists
Habitat loss/modification
- trawling
- channelization
- dam building
Trawling effects
- big heavy net with steel doors rips apart the sea floor when dragged across
- takes the big fish away from the juvenilles
- mining resources, some of this fish can’t reproduce quickly and could extripate them
