Lecture 1 - Fish Habitats

Question 1

What is a fish?

Answer 1

Poikilothermic, aquatic chordate with appendages (when present) developed as fins, whose chief respiratory organs are gills and whose bodies are usually covered with scales.

Question 2

Definition of a fish:
________ aquatic ______ with appendages (when present) developed as _____, whose chief respiratory organs are _____ and whose bodies are usually covered with ______.

Answer 2

Poikilothermic
Chordate
Fins
Gills
Scales

Question 3

What does poikilothermic mean?

Answer 3

Internal temperature regulated by the environment.

Question 4

What are the two reasons that fish are not cold blooded?

Answer 4

1 - Fish in warm water have warm blood
2 - Some fish (e.g. tuna) can increased their body temperature above ambient using different sorts of muscles to heat blood up

Question 5

A chordate is any animal with ____ ____ at some point in development; a dorsal _______ _____ cord; a _______ at some point in development, and a _____-_____ tail.

Answer 5

gill slits
hollow nerve
notochord
post-anal

Question 6

All _______ are _______ but not all ________ are ________.

Chordates or vertebrates

Answer 6

All vertebrates are chordates.

Not all chordates are vertebrates.

Question 7

What are the ecological factors that fish have to worry about?

Answer 7

Food, predation, invasive species, spawning habitats.

Question 8

What are the environmental parameters fish have to worry about?

Answer 8

Salinity, how much water is present, temperature, light intensity, pH, depth, DO

Question 9

What drives species diversity locally?

Answer 9

Temperature, depth (to some extent), light intensity - diel cycling, turbidity levels

Question 10

Variation in turbidity levels can vary due to natural and anthropogenic factors. Explain.

Answer 10

Natural - some fish prefer murky waters and some prefer clear waters
Anthropogenic - stirring up sediment

Question 11

Sturgeon are a massive, long-lived local fish. They were though to be locally extinct but, have a made a resurgence locally. Explain and indicate which is the most important factor.

Answer 11

1 - Dr. Pitcher started revamping spawning habitats
2 - Decreased turbidity (most important.
3 - Increased quality of environmental parameters

Question 12

What are the outer ranges of salinity in which fish can survive.

Answer 12

0 - 140 ppt

Question 13

At 140 ppt, what occurs?

Answer 13

Salt crystallizes out of solution

Question 14

Why does depth matter? i.e. what factors are related to depth?

Answer 14

1 - Light (the deeper you go, the less light there is)
2 - Temperature (Deeper water will generally be colder’ up to a certain point)
3 - Pressure - increases linearly with depth (1atm/10m)

Question 15

Describe the temperature ranges in which fish can be observed.

Answer 15

-2°C to 40°c

Question 16

What are the issues at the upper range of the temperature spectra? The lower range?

Answer 16

High temps. - cellular degradation and denaturation of proteins
Low temps - freezing

Question 17

Most fish do better at ____ temperatures than _____ temperatures.

Answer 17

high

low

Question 18

There is roughly ____ distribution of fish species between marine and freshwater systems, however there are more in ______ environments compared to _________.

Answer 18

even
marine
freshwater

Question 19

Why are there more marine fish than freshwater fish?

Answer 19

1 - Fish evolved in marine environments and then moved to freshwater
2 - There is more seawater than there is fresh

Question 20

Why is there so little freshwater?

Answer 20

Much of the freshwater is unavailable under the form of glaciers

Question 21

What drives species diversification in freshwater?

Answer 21

These are highly productive environments.

Question 22

Why are freshwater environments highly productive?

Answer 22

Lots of nutrient input from land

Question 23

_________ drives species diversification. (Related to food)

Answer 23

Productivity

Question 24

What areas are productive in strictly marine environments?

Answer 24

Coastal zones

Question 25

What is an estuary? What type of water is located there?

What are they important for?

Answer 25

Estuaries are a combination of both fresh and saltwater and are the locations where freshwater meets the ocean.
They are composed of brackish water, i.e. are within 0-32 ppt (32 being open ocean and 0 being freshwater)

Estuaries are important nursery grounds for marine fish.

Question 26

Define a lotic environment.

Answer 26

High flowing environment with lots of water flow. River or stream.

Question 27

Define a lentic environment.

Answer 27

Low flowing environment. Characteristics of a lake.

Question 28

Why do we care about flow?

Answer 28

It can drive species diversification since flow affects morphology.
In a higher flow environment, the fish needs to be more hydrodynamic.
In a lake system, the fish can be more blobbed shaped.

Question 29

What are the different oceanic habitats (related to depth)?

Answer 29

Pelagic
-epipelagic
-mesopelagic
-bathypelagic
--Abyssal
Benthic/Benthal

Question 30

What does pelagic mean?

Answer 30

Generally refers to the open water. i.e. the top and not the bottom

Question 31

What does benthic mean? Benthal?

Answer 31

Fish associated with the bottom.

Officially, benthic means the bottom and benthal means near the bottom.

Question 32

In the ocean, the pelagic zone is split into three zones. These are?

Answer 32

Epipelagic, mesopelagic, bathypelagic

Question 33

Describe the epipelagic zone.

Answer 33

• Top layer, ranging from 0-200m in depth.
• Most oceanic fish are found here
• lots of biomass
• photosynthesis is higher than respiration
• also called the euphoric zone - means that light is not limiting during the day

Question 34

Describe the mesopelagic zone

Answer 34

• Roughly from 200m-1000m in depth
• Light is available throughout most, if not all, of the water column
• light attenuates as depth increases
• vision can still be used here
• photosynthesis is less than respiration
• reduction in biomass with depth
• permanent thermocline

Question 35

As we go deeper in the mesopelagic what occurs? What adaptations has this caused?

Answer 35

3 things:
1 - Reduction in light
–>fish will have larger and larger eyes. Adaptation allowing for more sensitive vision to catch every photon of light
2 - Reduction in biomass
–> fish have to be more efficient at hunting
–> mechanisms to reduce metabolic demand
3 - Permanent thermocline
–> deeper is colder
–> species will choose where to live in water column based on preferred temperature

Question 36

What is a reason that there is a permanent thermocline in the mesopelagic?

Answer 36

Too deep for surface mixing

Question 37

Describe the bathypelagic zone.

Answer 37

• Anything below 1000m
• no sunlight
• reduction in eyes
• sensory adaptations to take over loss of eyesight
• always cold, no thermocline
• no seasonal cycling in temperature

Question 38

What are the issues bathypelagic fish face?

Answer 38

Cold, dark, poor amount of food, hard to find mates

Question 39

What is the term used for really deep living fish? What zone is it part of?

Answer 39

Abyssal, part of the bathypelagic

Question 40

Describe the abyssal zone

Answer 40

• Below 4000m

- fish live in open gashes on the sea floor

Question 41

What is the deepest fish have been observed?

Answer 41

8300m