LEC 29 - FISHES

Question 1

why does fish diversity in NA seem to be a lot lower than elsewhere?

Answer 1

glaciation wipes out fish species, and glaciation occurred relatively recently over canada

Question 2

what is the relationship bw species diversity and:
- lake size
- watershed size
- depth
- altitude
- temp

Answer 2

lake size: [+] w species diversity

watershed size: [+] w species diversity

depth: [+] w species diversity (shallower lakes are more prone to drying out, so species die out)

altitude: [-] w species diversity (higher altitudes were first hit by glaciation + its just generally harder to live up there)

temp: [+] w species diversity (higher temp = shorter generation time, so adaptations get in faster)

Question 3

post glaciation, how did fish get into alberta?

Answer 3

fish recolonized via the missouri-mississippi river, yukon beringia (wasn’t affected by glaciation) and the columbian river

Question 4

we say form follows function. what does that mean for planktonivores, piscivores, and benthivores?

Answer 4

predators (ptoniv + pisciv) have long slender bodies for acceleration, while benthivores have thick fins for maneuverability (no need to rush = mosey around)

Question 5

fish experience ontogenetic diets. what?

Answer 5

ontogenetic diet = diet changes throughout development

ie most fish are ptoniv while juveniles, pisciv while adults

Question 6

what is the relationship bw growth/development and temp (its giving zool 241)

Answer 6

as temp gets higher, metabolism needs to work harder to keep the body at eq
– more energy devoted to maintenance = less energy for development

Question 7

how can oxygen serve as a control on fish biomass?

Answer 7

fish need oxygen.. duh

in winter, fish kills can occur bc ice isnt oxygenated

in summer, fish can die off when littoral zone is above the thermocline, where super intense diurnal swings can cause deoxygenation (i dont get it but thats what it says idk)

Question 8

just in case this is question on the final what are controls on fish abundance?

Answer 8

oxygen, temp, and within-system biomass (predation/competition)

Question 9

what are the roles of fish in aq systems?

Answer 9

integrate disparate habitats, predation, providers of nutrient subsidies (go piss girl)

Question 10

what did nerka vs grant lake tell us about nutrient subsidies provided by fish?

Answer 10

anadromous fish (live in SW, spawn in FW) delivered lots of nutrient subsidies to FW systems in death.

until 1900s, nerka had lots of N inputs from ana fish
however, fishing began, and then N inputs decrease greatly
in fact, they matched that of grant lake, which had no ana fish inputs

Question 11

zptoniv fish diets are high in what?

Answer 11

lipids, since copepods contain lots of wax esters

Question 12

herbiv fish eat their veggies. what adaptations do they have?

Answer 12

special enzymes to break down food, or longer guts for longer digestion processes

Question 13

descr periodic, opportunistic, and equilibrium life strategies

Answer 13

periodic: delay reprod to grow bigger, have a bunch of kids at once and surely some will survive

opportunistic: mature early, reprod freq in low numbers and one will survive eventually

equilibrium: do well in stable conditions, where density dependent effects are strongest. have a few kids, and make sure they survive.