FRESHWATER BIOLOGY (Biol 207)

Fall 1996

Final Exam - 150 pts

Name:

Definitions (1 pt each)

1) caviar -

2) CPOM-

3) nekton -

4) meroplankton -

5) catadromous -

6) biomagnification-

Short Answer (2 pt each, unless noted otherwise)

1) How can zebra mussels promote the growth of sumergent macrophytes?

2) What aspect of the reproductive biology of lake sturgeons make them particularly vulnerable to overfishing? (3 pts)

3) List 2 ways phytoplankton are similar to macrophytes & 2 ways they are different.

(4 pts)

4) Label the stream orders for the system shown.

5) One way to permanently mark the identity of fishes is via fin clipping. Which fin would you choose and why?

6) Where in a river system -- upstream or downstream -- would you more likely find a fish with a well-developed gas bladder and one with a poorly developed (or no) gas bladder and why? (3 pts)

7) Aquatic plants can elevate DO levels but it doesn't happen (a) every day and it doesn't happen (b) all hours of the day - why not for each case?

8) Do mobile or less-than-mobile fish have smaller scales & why? (3 pts)

9) Many species of larval insects drift downstream at night. Given this, how can these species maintain long-term populations in a given section of a river system?

10) Plot the DO levels in blood and water as they proceed through/over a gill that doesn't have countercurent flow. (4 pts)

11) You are a profundal organism (sorry) in a typical lake in late summer. List 2 ways your environment contrasts with that of a littoral organism.

12) Fish species "A" spawns and guards a nest of fertilized eggs. Species "B" spawns but doesn't guard. Which species is likely to have higher fecundity and why? (3 pts)

13) In bog environments you find plants that retain their leaves for long periods of time, and/or contain high levels of anti-herbivory compounds, and/or eat bugs. What is the common driving force for these attributes? (3 pts)

14) Your job is to delineate the borders of wetlands. Could you ever declare a lake littoral zone a wetland? Why or why not? (3 pts)

15) Explain the concept of "match-mismatch" and how this is important to fish populations. (3 pts)

16) Give an example of a "non-point" and a "point" source of pollution

17) Explain 2 ways (one abiotic, one biotic) in which eutrophication in Lake Erie has been stopped and even reversed. Which way is more fundamentally important and why? (5 pts)

18) Why do internal levels of toxic compounds tend to increase over the life of an organism?

Longer Answer (but not too long)

1) Compare/contrast the (a) approaches, (b) rationale, and (c) general results of 2 fish population-enhancement programs we heard about: (1) brook trout, and (2) salmon cultured in hatcheries. (12 pts)

2) Are (a) shredders, (b) grazer/scrapers, and (c) collectors more abundant up- or downstream in a river system and why? (12 pts)

3) Give 4 reasons why anadromous fish migrate. (8 pts)

4) Compare/contrast the following parameters of a lake and a river (comparable depth, geographic location): (8 pts)

a) Temp. from top to bottom

b) DO from top to bottom

c) water clarity

d) relative importance of internal plantlife as food vs external plantlife

5) In the fall of a given year, you sampled the largemouth bass populations of 2 lakes (each located in the same small county in New York state) of similar size, shape, and depth. In your sampling program you were able to carefully collect, count and size all individuals, spanning the year classes 0+ through 6+. In lake "A" you found the growth rate of the entire population of bass to be higher than that of Lake "B", but you also found higher yearly mortality in lake A. (20 pts)

a) draw these situations graphically and explain/demonstrate the previously mentioned findings.

b) which lake would more people want to fish and why?

c) which lake is more eutrophic and why?

d) what could be causing the higher mortality of lake A?

e) which lake would you recommend to have the lower "catch limit" (number of fish taken per day) and why?

f) a resident of lake B introduced a non-native zooplankter to the lake in hopes that it would provide the food base necessary to increase the bass population. Could this work? Why or why not?

6) You're a scientist who has studied changes in a large river system for several decades. Your studies indicate that water temperatures have steadily increased (though air temperatures have not), water clarity has declined, dissolved N & P have increased, and tree leaf material has declined. You've also made many assessments of water quality by analyzing benthic invertebrates. (14 pts)

a) list and explain 2 trends in watershed use that might lead to such changes

b) provide likely trends in FBI and SW biotic index data over this time period

i) before noting trends, explain how these indeces are different from each other (ex. what do they measure and express?)

ii) explain how/why trends in these indeces might relate to the overall long-term changes noted above.

7) Lake Ontario has felt the effects of many exotic species invasions. Four key exotics are (1) Pacific salmon (large predator, mainly on other fish), (2) sea lamprey, (3) alewife (a small-medium sized fish that filter-feeds on many types of plankton), and (4) the zebra mussel. (8 pts)

a) how might the salmon population levels be affected by alewives?

b) how might the salmon population levels be affected by sea lampreys?

c) how might zebra mussels affect the salmon?

d) how might restrictions on P inputs to the lake affect each of the exotics?

8) As our atmospheric ozone layer thins, and more UV radiation (a harmful type of light energy) reaches the earth and its aquatic systems: (12 pts)

a) what type(s) of plant life in a somewhat eutrophic lentic system might be affected by higher UV?

b) what type(s) might not be as affected and why?

c) what repercussions (from part "a") might there be to the following members of the food web?

i) microscopic animals floating in the pelagic zone

ii) profundal invertebrates

iii) top-predators like northern pikes

EXTRA CREDIT (5 pts each)

1) Why do some tropical frogs take >1 yr to mature?

2 ) What main effect is causing the decline in certain frogs in the tropics?