Lecture 25- adaptations to temperature

Question 1

are fish better able to adjust to a rise or drop in temp?

Answer 1

not great in rises of temp

Question 2

why is a rise in temperature often deadly for fish

Answer 2

waters inability to hold oxygen at high temperatures where 30 degrees is a general cut off. Like all animals hen fish are heat shocked they produce heat shock proteins to protect other proteins from being denatured but this is very energy intensice and coupled with O2 drop can by fatal

Question 3

what are some biochemical adaptations to adapting to cold temps?

Answer 3

1. produce glycoprotein molecules that absorb ice crystals before they can shred cells 2. some fish have no hemoglobin or myoglobin which thins the blood, making it easier to pump. to compensate they have twice the blood volume and capillarie and double the average heart rate. ex.) crocodile icefish (you can get away with no hemoglobin because of the really high O2 concentration in cold water)

Question 4

whatr are morphological adaptations some fish use to keep warm?

Answer 4

1. some fish generate body heat using a trick of blood circulation (counter current exchange). the heat generated by muscles is maintained by a countercurrent heart exchanger. Common in tunas and sharks 2. constantly swim generating friction with the fin muscles ex.) shark and tuna 3. counter current exchange within the gills that allows warm blood to be pumped around the entire body including its brain ex.) opah 4. organs surrounded by fat to retain heat ex.)opah 5. billfish take energy they would used in movement and use it to create heat in a process called non-shivering thermogenesis

Question 5

what are behavioural adaptations to temperture?

Answer 5

1. sunbathing by tuna or sunfish in the open ocean is common. this can warm the body by 4 degrees incresing muscle power and agility and llowing the fish to then chase prey into deeper and colder waters. 2. can also involve daily or seasonal migrations. fish can move into shallow water to warm up and move to deeper cooler waters to rest

Question 6

what are some life history adaptations in northern regions?

Answer 6

1. fish have genetic gender determination so that temperature has no impact on gender outcome 2. fish breed over a short period in summer taking advantage of warmer temperatures 3. the growing season is short so the vast majority of feeding occurs in the ice off season

Question 7

describe how fish in northern climates must adapt to significant but predictable changes in temp and oygen annualy

Answer 7

SPRING: the lake has uniform temp and ozygen profile SUMMER: the surface warms and the depths remain cold. O2 levels at the bottom are anoxic because there is not plants or wave action that brings oxygen to those depths. FALL: temp and O2 are uniform again. turn over event WINTER: warmer water is found at the bottom and the colder water near the ice and Oxygen levels in bottom are anoxic.

Question 8

what are life history adaptations in southern regions:

Answer 8

1. show temperature dependent gender determination. the gender is determined by temp instead of chromosomal gender determination systems. The eggs are affected during thermo-sensitive period. 2. breeding occurs over an extended period, often associated with peak rainfall 3. growth is still seasonal but does not stop as seen in northern climates

Question 9

what are the three patterns of temperature dependent gender determination in nature:

Answer 9

1. low tempertures produce female biased rations and high temperatures prodyce male biased sex ratios 2. low temperature produce males and high temps produce females 3. male biased sex ratios are produced at low and high temps while balance sex ratios are produced at intermediate temperatures

Question 10

fish posses which type of temperature dependent gender determination

Answer 10

2 or type B

Question 11

how do hydrodrams cause thermal pollution?

Answer 11

hydrodams draw water from as deep as possible using the natural pressure of the depth to drive turbines. water temp is lower than surface water. In the south saskatchewan river it takes around 100km for the river downstream of the dam to return to natural temps

Question 12

how has ocean temperature changes affected species composition?

Answer 12

in the sub tropic and temperate regions there has been a change from cool water species to warm water species. in the tropics there was a switch to warm water species.

Question 13

in review: what are the 4 major ways fish adapt to deal with temperature

Answer 13

1. biochemical
2. morphological
3. behavioural
4. ecological adaptations