stream ecology- fishes

Ray‑finned fishes (Actinopterygii) with typical fish anatomy.

What group do most people think of as “true fish”?

Gills, fins, lateral line, swim bladder, streamlined body.

List key anatomical features common to many fishes.

Trophic cascades affecting algae, invertebrates, and nutrient flow.

What kind of ecological effects did fish show?

consume algae faster than it can regrow, reducing biomass.

How do herbivorous fish affect algae?

Algae grows back because grazing pressure is reduced.

What happens when predators are added to herbivorous fish systems?

Longfin dace and stonerollers.

What fish species helped demonstrate strong grazing impacts?

Bears, which carry salmon carcasses into forests.

What animal links salmon to forests?

Up to 50% in some systems.

How much forest nitrogen can come from salmon?

By consuming aquatic insects before emergence.

how can fish reduce nutrient export to land?

limits food for terrestrial predators like spiders.

Why does reduced insect emergence matter?

Yes, depending on fish activity and system conditions.

Can streams be nutrient importers instead of exporters?

Water creates strong drag forces.

Why is swimming energetically expensive?

Different shapes offer advantages in different flow conditions.

Why are fish body shapes so variable?

Whole‑body undulation; good for tight spaces.

What is anguilliform swimming?

Partial body movement; useful in many habitats.

What is carangiform swimming?

Tail‑powered, fast, continuous swimming with minimal body movement.

What is thunniform swimming?