Final Exam Concepts Part I

Question 1

Kelp

Answer 1

Characterized by their large size and complexity. Some form dense kelp beds or kelp forests. Large seaweeds belonging to the brown algae. Prefers colder temperatures.

Question 2

Seagrass

Answer 2

Grass-like flowering plants like eelgrass that are adapted to live at sea.

Question 3

Sub-tidal

Answer 3

The bottom above the continental shelf.

Question 4

Detritus-based food web

Answer 4

Consists of a base of organisms that feed on decaying organic matter (dead organisms), called decomposers or detritivores. These organisms are usually bacteria or fungi that recycle organic material back into the biotic part of the ecosystem as they themselves are consumed by other organisms.

Question 5

What are the environmental conditions required for Kelp and for Seagrass ecosystems? What kinds of organisms are kelps and seagrasses (to which Eukaryotic kingdom does each belong)?

Answer 5

Kelp: cold, Nutrient-rich water, rocky bottom, high energy, lighted bottom, light penetration of 20-40 meters,
typically found on the west coast. Kelp belongs to the Protista kingdom because they have no leaves, stems,
or roots.
Seagrasses: Nutrient-poor water, sandy bottom, low energy, typically found on the east coast. Seagrass
belongs to the Plantae kingdom because they are true plants and truly marine (they have roots and other
plant characteristics).

Question 6

Understand how Sea Otters affect the health of Kelp forests.

Answer 6

Sea otters are keystone species because they eat sea urchins. Sea urchins eat sea kelp, so if there are not
enough sea otters to eat the sea urchins, the kelp forests will be depleted.

Question 7

Understand what a detritus-based food web is, and recognize that seagrass beds (among others) are an example of such food webs.

Answer 7

Detritus consists of nonliving organic matter in solid form. Examples of detritus are decaying seaweeds,
cast-off seagrasses, and dead organisms. Decomposers help channel DOM and detritus back into the food
web. If there were no decomposers, the waste products and dead bodies would accumulate instead of
rotting away.

Question 8

Be aware of the trend in the extent of seagrass beds worldwide, and be familiar with the potential causes of this trend.

Answer 8

There is a net decline of 7%/year since 1990. “The combination of growing urban centers, artificially
hardened shorelines, and declining natural resources has pushed coastal ecosystems out of balance.
Globally, we lose a seagrass meadow the size of a soccer field every thirty minutes.” Causes of this trend
include dredging, damage from boat propellers, “wasting disease”, and especially eutrophication (or harmful
nutrients being added to the environment due to agricultural and urban run-off.

Question 9

Fishery

Answer 9

An entity engaged in raising or harvesting fish which is determined by some authority to be a fishery.

Question 10

Fishing Effort

Answer 10

A measure of the amount of fishing. Frequently, some surrogate is used relating to a given combination of inputs into the fishing activity, such as the number of hours or days spent fishing, numbers of hooks used.

Question 11

Sustainable Yield

Answer 11

The ecological yield that can be extracted without reducing the base of capital itself, i.e., the surplus required to maintain ecosystem services at the same or increasing level over time.

Question 12

Maximum Sustainable Yield (MSY)

Answer 12

The maximum catch of a stock that can be harvested year after year without diminishing the stock.

Question 13

Catch per Unit Effort

Answer 13

An indirect measure of the abundance of a target species.

Question 14

By-catch

Answer 14

Non-target catch that is taken while fishing for other species.

Question 15

Exclusive Economic Zone (EEZ)/High Seas (International Waters)

Answer 15

A zone 200 nautical miles wide along the coast where nations have exclusive rights to any resource.

Question 16

“Tragedy of the Commons”

Answer 16

An economic theory of a situation within a shared-resource system where individual users acting independently and rationally according to their own self-interest behave contrary to the common good of all users by depleting that resource.

Question 17

Understand the relationships between population size and population growth rate, and between fishing effort and population size.

Answer 17

As time progresses, the population size increases. Population growth progresses from slow growth to fast
growth and then eventually back to slow growth again. As fishing effort increases, population size may be
depleted due to overfishing.

Question 18

Know and understand the shape of the catch versus effort curve.

Answer 18

Population size decreases as fishing effort increases. Fishing effort can be affected by a number of factors
including: number of boats, days spent fishing, etc. The catch-effort curve eventually reaches a maximum
sustainable yield at its peak. Once it has reached its peak, the sustainable catch decreases due to
overfishing.

Question 19

Understand Maximum Sustainable Yield.

Answer 19

In population ecology and economics, maximum sustainable yield, or MSY, is theoretically, the largest yield
(or catch) that can be taken from a species’ stock over an indefinite period. Population size starts to
decrease once the maximum sustainable yield has reached its peak. The MSY is about half of the
population size.

Question 20

Know the typical history of a commercial fishery: how does catch and fish population size change over time, and why?

Answer 20

Fish will collapse and become economically extinct before the fish population will go extinct. Over time, the
fish abundance will deplete. Market forces will cause fishers to continue to fish if there is a profit to be made.
Total profit from the fishery decreases, however, because in the long run, the population will deplete and
possibly disappear due to overfishing. This is what happen when fisheries are left unregulated.

Question 21

Know (in a general way) how world-wide marine fish catch has changed from the 1950s to present.

Answer 21

The catch per unit effort has decreased by 50% in the past 50 years.

Question 22

Understand the status of world fisheries - i.e., how is the proportion of under- and over-exploited fisheries changing?

Answer 22

Overexploited fisheries have increased, while the percentage of underexploited fisheries has decreased.

Question 23

Know (in a general way) trends in the size of top predator populations in the world’s oceans over the past few decades.

Answer 23

Large predatory fish populations have decreased by 90% in the past 50 years.

Question 24

Understand the effects of commercial fishing on the target fish species: size of populations; size of individuals.

Answer 24

Large-scale fishing reduces the size of the population. It also makes the size of each individual fish in the
population smaller. Example: Tuna fishing.

Question 25

Understand the effects of commercial fishing on the rest of the ecosystem: by-catch, changes in the environment, changes in competition/predation.

Answer 25

There is by-catch, which is the other fish caught in the net accidentally. These fish die and are ultimately
thrown back into the ocean. About 20-30% of total catch is by-catch. By-catches include turtles and dolphins.
Another effect from commercial fishing is always Habitat Disturbance. Trawling will drag the net on the
ocean floor, resulting in a stunted ecosystem. Competition and predation is also affected when there is a
change in the amount of fish species.

Question 26

Understand how killer whales, sea lions, sea otters, kelp forests, and sea birds might be affected by the large Alaska Pollock fishery in the Gulf of Alaska.

Answer 26

Loss of prey/more competition for seabirds. In Alaska with Pollock fishing, birds that eat zooplankton are
thriving because there is less Pollock for competition for food. However, the birds that eat the small Pollock
are suffering because there is increased competition with humans for fish. The sea lion population is
endangered because the only eat large Pollock, which is drastically reduced because of fishing by humans.
Whales eat Pollock and sea otters, so if there’s a depletion of Pollock, the whales will eat more sea otters. If
the sea otters are eaten, then they won’t eat the sea urchins. If the sea urchins are increasing in population,
this could be really harmful for kelp forests, because kelp are what the sea urchins eat. This is an example
of a trophic cascade.

Question 27

Corals

Answer 27

Marine invertebrates in the class Anthozoa of phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. Most corals are asexual and are what’s called a clone colony. They are hermaphrodites.

Question 28

Zooxanthellae

Answer 28

Dinoflagellates that live within the tissues of reef corals and other marine animals - help make calcium carbonate skeletons.

Question 29

Fringing Reef

Answer 29

A coral reef that develops as a narrow band close to a shore.

Question 30

Barrier Reef

Answer 30

A coral reef running parallel to the shore but separated from it by a channel of deep water.

Question 31

Atoll

Answer 31

A coral reef that develops as a ring around a central lagoon.

Question 32

Crown-of-Thorns Starfish

Answer 32

A predator of reef corals.

Question 33

Coral Bleaching

Answer 33

When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white.

Question 34

Ocean Acidification

Answer 34

Decrease of seawater pH as a result of increased carbon dioxide. The increase of CO2 means that the the pH of the water decreases and the water becomes more acidic.

Question 35

Know the general structure of corals.

Answer 35

Each polyp is connected to each other, each polyp is a clone in the colony.
Identity: Photosynthetic cells that help coral photosynthesize.

Question 36

Understand the nature of the symbiosis between corals and their Zooxanthellae.

Answer 36

Zooxanthellae are primary producers for Coral Reefs. They provide food for the corals. Zooxanthellae do
photosynthesis, which has a byproduct of organic matter. The coral uses the organic matter as food
supplements. The polyps get nitrate and phosphate from the other foods they eat, which the zooxanthellae
need to live.

Question 37

Understand (in a general way) coral reproduction.

Answer 37

They reproduce asexually to increase the size of their coral. Corals need a hard substrate to begin growing.
After awhile, the corals will make their own hard bottom. New clonal polyps bud off from parent polyps to
expand or begin new colonies. Coral larvae are either fertilized within the body of a polyp or in the water, through a process called spawning.

Question 38

Know the geographical distribution of coral reefs, and their environmental requirements.

Answer 38

Environmental Requirements - water temperature greater than or equal to 20°C (68°F), salinity = full strength seawater, clear water, light, hard bottom (initially).
Distribution - tropical islands, Great Barrier Reef

Question 39

Understand how atolls are formed.

Answer 39

Once volcanic islands become dormant, they start to subside back into the ocean. As the island sinks, the
reef grows upward fast enough to remain in the sunlight column, and will continue to grow while the island
disappears. The volcanic island slowly sinks, going from fringing reef to a barrier reef to eventually an atoll
once the island is completely sunken and just water remains.

Question 40

Be aware of some of the organisms that eat corals.

Answer 40

The Crown of Thorns, a starfish, eats corals. It distends its stomach over a section of coral, eating all of the
polyps in the area and killing the coral. Also, the Chevron butterflyfish, Spectacled Parrotfish, and the
Humphead parrotfish.

Question 41

Know (in a general way) the level of primary production that occurs on coral reefs, compared with other ecosystems.

Answer 41

It has the highest level of production out of all the ecosystems, even the rainforest. The next highest level of production comes from salt marshes.

Question 42

Be familiar with examples of mutualism in coral reef ecosystems.

Answer 42

Humpback Cleaner Fish on Tomato Cod, Zooxanthellae provide food for the coral through photosynthesis and the coral provides nitrogen and protection, protector crabs protect the coral against Crown of Thorns starfish and get a home in return.

Question 43

Be aware of the current threats to coral reef health (Eutrophication, Overfishing, Ocean Warming).

Answer 43

Eutrophication: When there are more phytoplankton in the water, the zooxanthellae cannot photosynthesize, and the coral population suffers.
Overfishing: Leads to a decrease in the number of fish that eat the existing phytoplankton, which means that the phytoplankton population increases, resulting in a destruction of coral.
Ocean warming: Higher temperatures can lead to bleaching of the coral reefs.

Question 44

Be aware of the relationship between seawater temperature and coral bleaching.

Answer 44

Increase in ocean temperature causes loss of zooxanthellae and results in stress to the coral and bleaching.