Exam 2 Chapter 4 Polar Communities

Polar regions consist of

arctic and antarctic

The polar regions experience

constant cold

Arctic temperature

- 0*C in summer

- -40*C in winter

Antarctic temperature

- -28*C in summer

- -60*C in winter

Which is colder?

Antarctic is colder

Why is the antarctic colder?

higher elevation, no water underneath to buffer heat exchange

Marine mammals are

ectotherms/homeotherms

What are the marine mammals adaptations for cold?

1. migration during winter

2. blubber layers

3. thick fur to trap heat

4. tusks

Tusks are for

grabbing onto ice and haul out

What covers the polar seas throughout the year?

ice

Polynas means

year-round areas of open water in ice cap

Polynas is caused by

currents of open water in ice cap

A large polynas

North Water Polynya

Polynyas are necessary for

air breathing mammals

Polynyas are high production in

spring, no ice blocking light

The polar experiences extreme

seasonal light fluctuations

How many hours of light during the summer?

24 hours

How many hours of darkness during the winter?

24 hours

The antarctic winter months is our

northern hemisphere summer months

Is each pole similar?

no, theyve evolved unique ecosystems based on differences

Physical characteristics of Arctic ocean

- relatively small, isolated body of water

- extensive, shallow continental shelf

The Arctic Ocean is surrounded by

2 land masses

The 2 outlets of the arctic ocean

1. Bering Strait to the Pacific

2. Fram Strait to the Atlantic

Freshwater rivers create

lower salinity layer on top of denser, saltier water

What causes soft, mud bottom in arctic rivers?

River discharge

Surface waters are at or near

freezing point of seawater

The freezing point of seawater

-1.9*Celsius

The surface waters being near the freezing point of seawater causes

floating caps of sea ice which expand and retreat with season

The water under ice moderates what?

temperatures

The floating cap of ice is largest in

april

the floating cap of ice is smallest in

september

In the Arctic, the most melting occurs over

continental shelves

The central areas of the arctic ocean stays

frozen (thicker, 3-4 m)

Sea ice is ______, unlike freshwater

porous

The spaces are filled with

high saline brine

The spaces filled with high saline brine allow for

1. No freezing

2. the channels to remain contiguous with seawater under ice

3. ice to contain algal community

Why is ice containing the algal community important?

it supports the polar food web

High primary production in the arctic occurs within

permanent ice

Long arctic summers allow for

light to penetrate

Upwelling brings

nutrients from the bottom

Photosynthetic diatoms (ice algae) are within

the ice, turns the ice brown

As ice melts in the summer,

blooms of algae create large zone of very high primary production

the high primary production supports

marine mammals and sea birds

Unconsumed food from blooms sink and support who?

the benthic community

Impact of less ice due to global climate change indicates that what will happen by the 2040s?

ice-free summers

Arctic amplification is a

feedback loop of warmer temps melting ice results in heat not reflecting due to lower albedo which leads to more heat being absorbed so more ice melts.

Warmer temps melting ice leads to

less ice meaning less sunlight and no heat reflect due to a lower albedo

Albedo is the

percent of light that is reflected

Melting water will cause the sea level to

rise globally, moving coastlines inward

The Intergovernmental panal on climate change (IPCC) estimates what?

that 1.4-2.8 feet of sea level will rise by 2100

Impact of less ice on primary production

more primary production as less ice is available to impede sunlight

Loss of what due to climate change?

unique sea ice ecosystems

Ice breeding is

species such as polar bears that are dependent on ice for breeding

Ice breeding is impacted by

shrinking ice

Less ice makes it easier and safer for

- fisheries to exploit resources

- oil and natural gas drilling

-open up shipping lanes

Difference between Antarctic and arctic waters

- Antarctic waters are not landlocked

- no rivers

- narrow/steeper continental shelves

- has seasonal fluctuations but almost disappear in summer

Not landlocked means

the southern antarctic ocean completely surrounds the continent

No rivers means

no low saline layer nor river sediment

In antarctic oceans, no river sediment means

it has a hard bottom

The Southern Antarctic Ocean is very high in

primary production

In the antarctic, thinner ice supports what?

strong ice algae populations (large diatoms)

Antarctic waters are what? What are they driven by?

very nutrient rich; driven by permanent upwelling

The nutrient rich north atlantic deep water does what?

sinks, flows southward for hundreds of years and emerges off of antarctica

In the antarctic, there are what similar to the arctic?

- more ice algae due to thinner ice (more light)

- more break up of ice

More breakup of ice releases what into water?

plankton

High primary production supports what in the antarctic?

krill, Euphausia superba

Krill are

shrimp-like zooplankton, 4-6 km long

Krill are adapted to

living without food during the winter

How have krill adapted to living without food in the winter?

- lower metabolic rate

- shrink size

- revert to juvenile state

Diatom bloom in spring is when krill experience

- rapid growth

- regain sexual characteristics

Simple food chain in the Antarctic

diatoms eaten by krill which are eaten by large animals

Who spends their summer in the southern antarctic ocean?

Blue, right, and fin whales

Adaptations of each species partition...

resources

Whale migration

- feed in antarctic in summer

- swim to northern waters to breed during antarctic winters

Penguins also eat

krill

Abundant species of penguins

there are several species, most common is Adelie (Pygoscelis adeliae)

Penguin juveniles are dependent on

krill

If Krill yields are low

high juvenile penguin mortality

Crabeater seals have

specially adapted teeth that can strain for krill

Leopard seals are

marine predators that prey on penguins and crabeater seals

Leopard seals also feed on

krill

Squid feed in

antarctic waters

The main prey for sperm whales are

squid

In the Antarctic Benthos, the seabed is scoured by

ice

Where are sessile animals absent from?

The antarctic benthos

When ice is absent in the Antarctic Benthos, what organisms are common?

mobile sea stars, sea urchins, nemetean worms

In deeper antarctic benthos seas, you'll find what organisms?

sessile orgs; sea anemones, corals, sponges

Anchor ice morality occurs when

very cold seawater freezes around organisms

When anchor ice mortality occurs,

buoyant ice lifts organisms

What exist under frozen ice?

arctic fish; sculpins, codfish, salmon, flatfish, eelpouts

All arctic fish have adaptations for

living in colder water

What else can be found in the arctic?

Cartilaginous fish such as Greenland shark

Ice fish are also called

Notothenoids

Most ice fish lack

hemoglobin (red blood cells)

By lacking hemoglobin,

blood stays thinner, good for cold water

Ice fish lacking hemoglobin allows them to compensate by

having more blood volumes, large hearts and large capillary beds

Ice fish have

antifreeze to prevent ice from forming in their blood

What collapsed in the 1960s due to overfishing?

whaling industry

When did commercial fishing begin?

- 1960s for mackerel, ice fish and patagonian toothfish

The patagonian toothfish (Chilean sea bass) populations are

unstable and overfished