Quiz 3 Lecture 3

Question 1

What are five factors affecting species prescence, abundance and performance?

Answer 1

Temperature
Light
Substrate
Oxygen Levels
River: Gradient, order, flow regime

Question 2

How does temperature impact fish species, presence, and abundance?

Answer 2

Different fish species have different tolerance, so if it’s too cool or hot you won’t see them there

Question 3

How does light impact fish spa?

Answer 3

Will impact what fish can see, visual predators that can’t see prey can’t eat them so food webs are affected

Question 4

How does substrate impact fish spa? Give an example?

Answer 4

Spawning habitats need specialized substrate, salmonids will form redds (nests in gravel)and deposit eggs and then males will come fertilize them, if there’s just giant bolders and no gravel male fish can’t reach to the eggs won’t be fertilized reducing success

Question 5

How do oxygen levels effect spa?

Answer 5

Some species are way more tolerant to variations in oxygen levels and eggs have diff requirements for oxygen for hatching

Question 6

How does river: gradient, order and flow regime impact fish spa?

Answer 6

The river might consistently flow or dry up later in summer- some species can’t deal with variation in flow.
Depending on the size of fish and their muscles, some can go upstream and colonize new habitats for reproduction
Human impact on the rivers will impact fish we see.

Question 7

What are piscivores?

Answer 7

Fish that eat other fish (can be lower down in the food chain)

Question 8

What are planktivores?

Answer 8

fish that eat plankton, some are only planktivores in infancy and then become piscivores, some species are planktivores throughout

Question 9

What are insectivores?

Answer 9

These are benthic macroinvertebrates and eat insects

Question 10

What are detritivores?

Answer 10

Are bottom feeders, eat detritus at the bottom of the environment

Question 11

How are the places where fish are located to the food chain?

Answer 11

We find detritus at the bottom so detritivores are found in the benthic zone, when planktivorous fish are present zooplankton are lower in the water column, some fish may also be in the littoral zone at night where predators can’t see them.

Question 12

What are the five modes of detecting prey?

Answer 12

visually
chemically (smell/sense it)
electrically (feel it through electroreceptors)
hydrodynamically (feel it through water movements)
Tactile (actually feel it)

Question 13

What species use the visual mode of detecting prey a lot?

Answer 13

A lot of planktivorous fish

Question 14

What do chemical cues do for preys? for predators?

Answer 14

for predators lets them know that prey is there, for preys lets them know to hide

Question 15

How does electrical sensing work in prey-predators?

Answer 15

predators sense prey produced by the bioelectric field of prey, it can work inversely

Question 16

Where is hydronamically sensing useful?

Answer 16

in low light and where visual cues not as useful

Question 17

What kind of species uses tactile sensing?

Answer 17

mouth feeders

Question 18

What fish are planktivorous their entire lives?

Answer 18

Whitefish
Alewife (Alosa)
Smelt (Osmerus)

Question 19

How does the adult alewife feed?

Answer 19

feed by pumping water through their mouths and retaining the zooplankton with
their gill rakers.

Question 20

What are gill rakers?

Answer 20

Is a filter like structure located in the gills, has size selectivity as it catches bigger plankton as larger particles are retained more easily

Question 21

Does size selectivity also apply to visual predators who catch with their mouths?

Answer 21

Yes, a visual predator will only see certain sizes of prey and their limitation of their mouth being too small to catch prey will skew them to catching small prey

Question 22

How does size selectivity affect prey community composition? Give an example?

Answer 22

In a study where Alosa was added, the zooplankton body length was initially larger, but after the predator ate the large ones the community composition shifted towards smaller body lengths, this is because also was filtering big zooplankton with it’s gill rakers

Question 23

What is reaction distance?

Answer 23

Is the distance in which the predator recognizes and reacts to prey

Question 24

Does local water conditions have an impact on visually orienting fish? Explain?

Answer 24

yes, as light intensity increases it is shown that fish (such as sunfish, brooktrout, and white trappie) increase their reaction distance, so there are able to see prey from a larger distance.

Question 25

Where do benthic insectivores/detritivores fish search for prey?

Answer 25

on plants and stones or in the sediments

Question 26

Do piscivorous fish eat their young sometimes?

Answer 26

yea

Question 27

What is the difference between top-down or bottom-up control?

Answer 27

In bottom up addition of nutrients causes change, in top down addition of top predators causes change

Question 28

Give an example of bottom up control?

Answer 28

Schindler experiment where he added phos, carbon, and nitrogen to one side of the lake and just phos to the other, this resulted in physical and chemical changes (less clear water)

Question 29

Give an example of top down control?

Answer 29

no nutrient changes, large mouth bass was added in to one lake which made the lake much clearer, this is due to the bass hunting the small planktivours fish, results in more schooling/going to the littoral zone, causing less efficient hunting of zooplankton which then caused the zooplankton to rise, which then causes the phytoplankton to decrease - resulting in clearer water

Question 30

What’s causing the difference between clear and turbid water states in shallow prairie lakes in Alberta?

Answer 30

Lack of planktivorous fish, when there was none there was lots of zooplankton and therefore less phytoplankton, the macrophytes then didn’t have to compete for light and were more abundant, the altered food web however had planktivores, this decreased zooplankton (especially large ones that are most important in eating phytoplankton) which then increases phytoplankton, this shades macrophytes so macrophytes decreased

Question 31

What are the seasonal trends in lakes with no fish?

Answer 31

More inorganic nutrients are exhibited in spring and more detritus, daphnia that are present peak as no predators which produces decrease in phytoplankton resulting in a clear water phase

Question 32

What are the seasonal trends in lakes with fish?

Answer 32

There’s no peak in dpahnia as fish eat em, since there’s no daphnia to eat phytoplankton we don’t see a clear water phase

Question 33

What does herbivory look like in an aquatic system?

Answer 33

Looks like the consumption of phytoplankton by herbivorous zooplankton

Question 34

What does grazing look like in an aquatic system?

Answer 34

Looks like predator-prey interaction in water where algae and bacteria are the prey organisms

Question 35

What is the clear water phase?

Answer 35

Is a lake condition characterized by low algal biomass and high secchi depth

Question 36

When is there a phytoplankton boom? Why?

Answer 36

During spring, due to high nutrient from mixing and increased light promoting growth.