TAMU OCNG 251 Final Exam Review Shamberger

Plankton

-floaters, can't swim faster than the current

-Most biomass on earth consists of plankton

-Small (high surface area to volume ratio)

-Buoyant- stay near surface

-Friction prevents them from falling

- Avoid being consumed

Limited ability to move

Phytoplankton

autotrophic: primary producers

Zooplankton

Heterotrophic: consumers

Nekton

-swimmers, can swim faster than the current

-Independent swimmers

- Most adult fish

- Marine mammals

- Marine reptiles

Benthos

-bottom dwellers, swimming is not their forte

- can live on surface of seafloor

- can live buried in sediment

- can swim or crawl through water above seafloor

- most abundant in shallow water

- many live in perpetual darkness, coldness, and stillness

Strategies for survival

- don't sink out of the photic zone

- maximize surface area to volume ratio

- camouflage & countershading

- more appendages in warm water to increase volume to surface area ratio

Diffusion

high concentration to an area of low concentration; seawater has more oxygen than the blood of the fish & blood of the fish has more CO2 than ocean water, so it diffuses into the ocean as the ocean diffuses into it.

This controls the exchange of water products in the gills (nutrients and waste get exchanged)

Osmosis

No diffusion because a dividing membrane won't allow salt to pass through, but does allow water to pass through

Marine fish maintain salt & water balance by

- drink large quantities of water

- secrete salt through cells

- small volume of highly concentrated urine

Freshwater fish maintain salt & water balance by

- Do not drink

- cells absorb salt

- Large volume of dilute urine

Gas exchange

- Animals extract dissolved oxygen O2 from seawater through gills

- Gills exchange oxygen and CO2 directly with seawater

- Low marine oxygen levels can kill fish

Gill structure and location varies

Transparency

elude predators and stalk prey

Disruptive coloration

large bold colors make animals blend into the background

Countershading

parts normally in shadows are light and parts normally in dark are light

Primary Productivity

the rate at which energy is stored in organic matter

Photosynthesis

uses solar radiation 99.9% of oceans biomass relies on this/ uppermost surface seawater and shallow seafloor Euphotic zone 100 meters

Chemosynthesis

uses chemical reactions

Iron hypothesis

effective way of increasing productivity in the ocean is to fertilize the ocean by adding the only nutrient that appears to be lacking- iron. Adding iron to the ocean also increases the amount of carbon dioxide removed from the atmosphere.

Runoff

can cause algae blooms fertilizer runs off

River input

it can mix in water

Upwelling

cooler, deeper, seawater is nutrient rich, high productivity

Strong along coastal regions and in high latitudes

Coastal upwelling

most common type and most closely related to human activity. Supports some of the most productive fisheries in the world. Typically due to along shore winds. Due to Coriolis Effect.

Upwelling at equator

result of Coriolis Effect causing a divergence of surface waters and pushing nutrient-rich water upward as a result. Seen in the Pacific and Atlantic, but NOT in the Indian Ocean

Upwelling in Southern Ocean

Large eastward winds blowing across Antarctica drive water away from the continent- causing cold, nutrient-rich water to replace the water along the coast. Not much productivity however, because not much sunlight

Why is marine life more abundant in coastal waters than open ocean?

- Nitrate phosphorous and iron silica from river runoff promotes growth

- solar radiation is higher in coastal waters

- Biological pump- moves CO2 from the euphotic zone to the seafloor

Producer

PP first level nourish themselves through photosynthesis, autotrophic, coral

Consumer

eat other organisms, heterotrophic, any fish

Decomposer

break down dead organisms

Biogeochemical Cycling of Nutrients in the Ocean

Look at picture

Trophic Level Relationships

-Only 10% energy is transferred to next trophic level

-1000 to 100 to 10 to 1

Food Chain

Simple. Primary producer to herbivore only consumes one thing

Food web

Several different things consume bread and several different things consume them

Biomass Pyramid

Number of individuals and total biomass decreases as you go to the successive trophic level

The role of microorganisms in the marine environment

Microscopic algae are directly or indirectly the source of food for more than 99% of marine animals

Maximum Sustainable Yield (MSY)

The amount of fish that can be taken out but you still will be able to reproduce efficiently

Overfishing is when you go beyond the MSY

By-Catch

Non-commercial species are taken up incidentally by commercial fishers. Dolphins, other marine mammals

By-catch may be up to 8 times more than the intended catch

Marine Mammals Act (MMA)

1992- tuna and dolphins swim together so the purse seine nets would catch them and drown them by accident then driftnets and gill nets were banned in 1989

Purse nets

encloses the school of fish and pulls them up- accidentally catches dolphins

Drift nets (gill nets)

boat drags out a huge net and any fish that swims into its (gills) will get stuck in it and sometimes it falls off so the fish are stranded in this huge net wandering around in the ocean

Dredging

Stirs up benthic environment and is very destructive (like a big dump truck sweeping bottom of the ocean floor)

How do consumer choices affect commercial fisheries

- 80% of fish are exploited beyond the MSY so the young juveniles can't reproduce to keep up

- Tragedy of the commons: you misuse shared resources because of huge populations

- Can be fixed when laws when laws are put into effect (like the ones for ozone depletion) where there is

1. Global participation

2. Technological solutions

3. Willingness of developed nations to help underdeveloped nations

- Consumer choices in seafood, pick healthy thriving fisheries like Alaskan salmon and avoid Tuna, shark, and shrimp.

Conditions for coral development

warm seawater, sunlight, strong waves, clear, hard substrate

Corals are mainly by these two continents

Asia & Austrailia

Corals are on the ________ boundary of oceans or _______ boundary of continents

West, East

Vertical Zonation

zooxanthellae are photosynthetic and need light

Horizontal Zonation

corals need wave action

Describe the symbiotic relationship between coral polyps and zooxanthellae

Zooxanthellae need a place to sit on and they provide the polyps with their color which attracts other organisms to come to it so the polyps can eat it.

What happens to the coral if the zooxanthellae die?

It becomes "bleached" so it dies

Biological functions that coral reefs serve in tropical marine environments

-Great diversity of species

-Important tourist locales

-Fisheries

-Reefs protect shorelines

How do coastal development, fishing, tourism, and farming/aquaculture affect coral reef health?

• Ocean acidification

• Increased surface temperature

• Sewage discharge and agricultural fertilizers

• Coastal development/ sediment influx

• 30% are healthy in today, while 41% were healthy in 2000

• 1/3 of corals are at a high risk of extinction

• Threats = humans (#1), hurricanes, invasive species, floods, tsunamis

• Ocean acidification: polyps are made up of calcium carbonate which dissolves when the water gets acidic, so coral dies

• Nutrient Loading: zooxanthellae survive in low nutrient environments so when there is too many nutrients, an overabundance of plankton comes in and they die

• Sedimentation: sediments get stirred up and leads to coral bleaching

• Sewage discharge and ag fertilizers get into water system and kill marine organisms

Polar Oceans are not _____ limited, but are _____ limited

nutrient, light

Tropical Oceans are not ______ limited, but are ______ limited

light, nutrient

Tragedy of the commons

shared resources tend to be abused because there's no sense of ownership which leads to overfishing

What gives coral its color?

Zooxanthellae

What is the central thing that allows gills to function?

Diffusion (high concentration to low)