Oceanography final Exam

Food from the Sea

• 1% of all food eaten

• 30% of animal-based protein

• Demand is increasing

Marine Fisheries

• Commercial fishing

• Most form continental shelves

• More than 20% from areas of upwelling that make up ~0.1% of ocean surface area

Status of Marine Fisheries

In 2019:

• 35.4% overfished

• 57.3% fully fished

• 7.3% underfished

True or false: Most marine fishery catches are harvested from the continental margins.

True!

Which of the following is NOT an example of increased fishing pressure?

a. Boats fishing more days

b. Boats hiring an additional deck hand

c. More boats fishing

d. Boats using better technology to find and track fish

b. Boats hiring an additional deck hand

Maximum Sustainable Yield

Maximum level at which a natural resource can be routinely exploited without long term depletion

Threats to Fishery Resources

• Overfishing

• Habitat destruction

• By-catch

• Ghost fishing

• Pollution

• Technology

Effects of trawling

Destruction to habitats

Ghost gear

Discarded, abandoned, or lost fishing gear

Gill Nets

Nets usually made of clear monofilament - fish swim into nets and are caught when their gill flaps through the net

Bycatch/incidental catch

Fish that are not the targeted fish but are captured

Trawls

Nets towed behind a ship, trapping anything not swimming fast enough. Some trawls have escape hatches to prevent bycatch

Purse Seines

Large nets that are deployed around large schools of fishes, and then cinched.

Longline

Similar to fishing with a fishing hook - baited hooks hang on long lines

Fisheries management

• Organized effort directed at regulating fishing activity to maintain a long-term fishery

• Reduce overfishing

• Restore depleted stocks

• Reduce by-catch

Major Species: Clupeoid Fishes

• Small, plankton feeding fishes

• Herrings, anchovies, sardines, menhaden and shads

• Continental shelf, upwelling zones

• Purse seines

• 19 million metric tons

• Human food, animal feed, oils for industry, fertilizer

• ISSCAAP Group 35

The boundary between the shore and coast is called the…

Coastline

Which of the following characteristics is NOT true for coastal waters?

Light never penetrates coastal waters to the seafloor

You are planning a sampling cruise to an area of ocean off NC (mid-latitude region) in late July. What description below fits characteristics for the water column you expect to find?

You expect to find a strong thermocline, with warm water at the surface and cooler water at depth.

When the water column is separated into layers by density, we call the conditions..

Stratified

Define estuary as an oceanographer would.

partially enclosed coastal body of water where fresh water from rivers or streams mixes with saltwater from the open sea

Coastal Plain estuary

Flooded river valley

Bar-built estuary

Lagoon isolated by barrier island or sand bar

Tectonic estuary

Flooded down dropped area created by faulting

Fjord estuary

Flooded glaciated valley

If you are in a very deep estuary formed by a glacier, which type of mixing regime do you expect to find?

Highly stratified

In which type of estuary can you expect salinity to be constant from the surface to the seafloor at any given location? (i.e. salinity does not change as you sample down through the water column?)

Vertically mixed

Unlike typical estuaries, the salinity of surface waters in a negative estuary

Decrease from the head to the mouth

Which of the following is NOT a domain in the accepted taxonomic classification system?

Prokarya

Which environment is more stable, making the organisms found there more susceptible to stress due to climate change:

marine environment

The overwhelming majority of the species living in the ocean are characterized as

Benthic

The purpose of life is to find food and avoid being eaten long enough to…

Reproduce

Which of the following is the correct definition of plankton?

Drifting organisms that cannot swim strongly against currents

In which group of organisms would you expect to find streamlined body shapes?

Nekton

Which of the following adaptations would improve buoyancy?

a. Increasing surface area to volume ratio with spines and extensions

b. Filling storage organelles with very dense, hypersaline brine

c. Streamlined body shape

d. Increasing density

a. Increasing surface area to volume ratio with spines and extensions

Which of the following would you expect to be the most viscous?

Cold ocean water

A sea cucumber living in the deep-sea experiences stable conditions including salinities that do not change over time. Since the animal is adapted to live in a narrow salinity range, we call it:

Stenohaline

Organisms that migrate over large distances, such as whales and leatherback turtles, experience cold and warm waters. As a result, they are characterized as:

Eurythermal

Photosynthetic organisms use chlorophyll to capture light energy. Chlorophylls absorb blue and orangish-red light best, but red light does not penetrate ocean water well. Which adaptations do phytoplankton use to circumvent this problem?

Increase buoyancy to stay as close to the ocean’s surface as possible, use accessory pigments that absorb the colors of light that do penetrate ocean water.

Many organisms in the deep sea are which color?

Red

The color pattern in which marine organisms are light on the bottom and dark on the top of their bodies is called:

Countershading

Which of the following are strategies for avoiding predation in the water column?

Diel migrations, cryptic coloration, transparent body

The process by which organisms use energy derived from solar radiation to form organic matter is called..

Photosynthesis

99.9% of the ocean’s biomass relies directly or indirectly on which form of primary production?

Photosynthesis

Which of the following is NOT required for phytoplankton to grow?

a. Waves

b. Sunlight

c. Nutrients

d. Carbon dioxide

a. Waves

In which area of the ocean is productivity lowest?

The centers of the subtropical gyres

You set up an experiment and incubate water samples is gas-tight, glass bottles. Some you incubate in the dark, and others you expose to light. Which chemical reactions are occurring in the organisms in the clear bottles exposed to light?

Respiration and photosynthesis

What chemical reactions are occuring in the organisms in the dark bottles with no light?

Respiration

Productivity in the tropical ocean is generally…

Nutrient limited

Productivity in the temperate ocean is…

Light and nutrient limited

Productivity in the polar ocean is…

Light limited

All ecosystems must have a flow of energy to thrive. What are the three basic categories of organisms required to maintain this flow?

Producers, consumers, decomposers

A food chain is…

Simple, direct, and involves one organism at each trophic level

The efficiency of radiant energy transfer into primary producers in food webs on average:

2%

The efficiency of energy transfer between trophic levels limits the possible number of trophic levels in a food web.

True

Pulling on knowledge gained from lectures and the Blue Planet video, which of the following statements is false:

• All kelp forests are lush year round.

• Kelp food webs are derital-based

• Kelp grow rapidly

• Sea urchins are one of the few animals that can graze directly on kelp.

• all kelp forests are lush year round

Which adaptation did the crab use to find its prey in the Blue Planet video?

It smelled the sediment with its legs and grabbed the prey

How did the leafy sea dragon at the end of the Blue Planet video protect its eggs?

The dragon hid in a seaweed that matched his camouflage.

Which of the following is NOT a challenge faced by intertidal organisms?

Drying out in the Sun during high tide

Reef building corals are hosts to a symbiotic, photosynthetic __ called a zooxanthella.

Dinoflagellate

Hydrothermal vent communities are associated with which ocean province?

Mid ocean ridge

Brine lakes under the ocean are associated with

Hypersaline seeps