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Conservation Ecology > Marine Conservation > Flashcards

Marine Conservation Flashcards

1
Q

How many species are there in the sea?

A

Around 300,000 that we know of, probably 500,00 total

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2
Q

Why is endemism more difficult at sea?

A

It is more difficult as it is interconnected

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3
Q

Where is the highest species richness found in a marine habitat?

A

To the best of our current knowledge, the highest species richness of any marine habitat is found in tropical coral reefs

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4
Q

What are coral reefs?

A

systems built on the calcareous skeletons of colonial anthozoa

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5
Q

Where can coral reefs be found?

A

Within 20 degrees of the equator in seas between 20-18C

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6
Q

How much of the Earth’s surface do coral reefs cover?

A

1%

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7
Q

Why do corals need clear water?

A

The algae that live on them need light

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8
Q

Why is agricultural run-off bad for corals?

A

It is fertiliser-enriched, leading to explosive algal blooms that smother the corals.

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9
Q

What is the name of the algae that live symbiotically on corals?

A

zooxanthellae

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10
Q

What happens if the sea temperature goes above 28C?

A

If the sea temperature exceeds 28C the corals undergo a process called bleaching in which they eject their symbiotic zooxanthellae, which usually prove suicidal

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11
Q

How much of the Great Barrier Reef died in the bleaching event of 2016?

A

22%

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12
Q

How does marine acidification occur?

A

CO2 dissolves into water to make the weak acid called carbonic acid.

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13
Q

How much has the sea already been acidified by? How much is it expected to be acidified by in 100 years?

A

the sea has already been acidified by 0.1 unit, and is projected to fall another 0.4 units in 100 years.

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14
Q

Why is acidification bad for species that live in shells?

A

High acidification pushes some areas below the point where shells can be formed

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15
Q

Why are the aragonite shells of sea butterflies corroding?

A

Their aragonite shells showed signs of corrosion in antarctic waters where cold and high CO2 pushed the aragonite below its saturation threshold. Note that this problem will start in the coldest waters, then spread as [CO2] rises.

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16
Q

The giant triton is harvested for its handsome shell - why is this bad?

A

It preys on crown-of-thorns starfish, a species that damages coral reefs badly

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17
Q

What are illegal actions that occur and are rarely prosecuted?

A

Using cyanide (which kills everything) or dynamite (which kills most animals and the structure of the coral) to catch fish

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18
Q

Why is divers anchoring to living coral bad?

A

It causes serious mechanical damage

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19
Q

What is zuckerman’s paradox?

A

In essence it states that under a free-market system non-renewable resources tend to be harvested sustainably, while valuable biological resources tend to go extinct.

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20
Q

Why is it economically rational to over fish?

A

Because the rarer something is, the more expensive it is

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21
Q

What is the MSY theory?

A

It stands for Maximum Sustainable Yield. It is built on a logistic model of population dynamics. But politicians compromise by taking a position between the target and what the fishing industry requested.

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22
Q

What are two reasons for the MSY theory not working in practice?

A

1) Populations don’t obey the logistic equation

2) Fishermen harvest money, not fish

23
Q

What does the logistic equation that MSY theory is based on predict?Why doesn’t this work?

A

That once a species is reduced from K to a lower level, that population always bounces back to K (which often isn’t true because competitors fill in gaps, reducing K).

24
Q

Give an example of a fish that is now expensive but used to be cheap.

A

Salmon was so cheap in Victorian times that workers went on strike after endlessly being fed salmon. Now salmon is expensive.

25
Q

What’s the problem with big slow-growing K species?

A

It’s more economical to exhaust the resource and turn it into cash and then invest it somewhere else (like with whales).

26
Q

What happened when 949 fishermen hit their quota for spiny lobsters in two months?

A

They rioted when they were denied permission to continue fishing and destroyed all the contents and records of the Charles Darwin research centre.

In the end, the government set an 84 ton quote, against conservationists advice.

27
Q

What is one solution as cod decline to the point where they are uncatchable?

A

Start eating other fish - like orange ruffy from deep waters around New Zealand

28
Q

What is a problem with fishing for the orange ruffy?

A

It takes 25 years to reach maturity and lives to 100 years so it would be wiped out very quickly.

29
Q

How does fishing impact albatrosses?

A

They are regularly caught on kilometre-long multi hooked fishing lines (to such an extent that the extinction of the species is a real possibility).

30
Q

What is the Albatross Task Force?

A

A task force set up by the RSPB dedicated to reducing the accidental killings of albatross that occur each year because of modern industrial fishing methods, and which are threatening to drive almost three quarters of all albatross species to extinction.

31
Q

Define bycatch

A

The official term used for this accidental, collateral damage to marine life caused by fishing

32
Q

How many albatross are estimated to be killed each year by longline and trawl fishing?

A

Around 100,000

33
Q

How can fishermen prevent seabird deaths?

A

1) Use weights to make the lines sink quickly
2) They can attach bird-scarers or ‘Tori’ lines strung with bright streamers to scare the birds off
3) They can adopt night netting (only setting lines between dawn and dusk when the birds are less active)

34
Q

Boris et al., 2006

A

He complied data showing the over-fishing reduces biodiversity but biodviersity promotes resilience in fish populations

35
Q

Which species was once described as the most common animal on Earth but is now facing extinction?

A

In 1969 the oceanic whitetip shark was described as the most common animal on Earth but is now facing extinction due to fishing for its fins.

IUCN = Endangered

36
Q

Reducing the ____________ of an ecosystem reduces the ___________ of fish.

A

Reducing the DIVERSITY of an ecosystem reduces the ABUNDANCE of fish.

37
Q

Marine reserves and no-catch zones bring an average of _____% improvement in biodiversity and an increase in ________________.

A

Marine reserves and no-catch zones bring an average of 23% improvement in biodiveristy and an increase in fish stocks around the protected area.

38
Q

What creates a dead zone?

A

When soil runoff causes eutrophication

39
Q

Define eutrophication

A

Excessive richness of nutrients in a body of water

40
Q

What species was discovered in 1741 and went extinct in 1768? Why did this happen?

A

Stella’s sea cow was confined to the seaweed beds of northern Japan. It was the largest sirenian ever known. It was toothless and slow moving. Hunted to extinction

41
Q

When did Great Auks go extinct?

A

People harvested the bird on its nesting grounds. All colonies were extinct in 1697 except one on the island of St Kilda. The last bird was trapped by locals and was beaten to death in 1840 after being accused of being a witch.

There was one last population off the coast of Iceland. A merchant realised they had great market value and caught them all and stuffed them. The last pair were killed in 1844.

This is also an example of birds becoming scarcer and their value increasing.

42
Q

What is the Allee effect? What is the anthropogenic allee effect?

A

It is shown in species that only nest at high densities: if the population falls they stop breeding. Flamingos work this way – to get them to breed in zoos you must surround them with mirrors in the mating season.

The Anthropogenic allee effect is when the same effects results from human decisions: in the case of the Great Auk it was the high price paid for rarity that killed it off.

43
Q

Why is there a concern for krill?

A

recent work from the BAS shows krill numbers on the Antarctic peninsula to have declined in last decade; these crustaceans feed on algae on underside of icebergs. They feed penguins and whales.

44
Q

What is causing cold water fish (like cod and sand eel) to disappear from the North Sea?

A

Overfishing and warming

45
Q

What are mangroves?

A

They are among the few angiosperms to grow in salt water and form dense species-rich inter-tidal forests (important nurseries for young reef fish)

46
Q

What is happening to mangrove swamps?

A

They are being depleted by conversion to commercial shrimp farms,

47
Q

Why is converting mangrove swamps into commercial shrimp farms bad?

A

Not only does this remove a valuable habitat but the shrimp farm requires major inputs of fish food, which eutrophies the water body and endangers offshore corals.

48
Q

What are the best ways to help marine biodiversity?

A

create marine reserves

49
Q

Roberts et al., 2001

A

We show that marine reserves in Florida (United States) and St. Lucia have enhanced adjacent fisheries. Within 5 years of creation, a network of five small reserves in St. Lucia increased adjacent catches of artisanal fishers by between 46 and 90%, depending on the type of gear the fishers used.

50
Q

Plaisance et al., 2011

A

Tropical reefs shelter one-third to one-quarter of all marine life

51
Q

Lough et al., 2018

A

Coral-algal symbiosis is essential for the functioning of reefs but thermal stress can break down this symbiosis and lead to bleaching

52
Q

Loreau et al., 2001

A

In changing environments, larger numbers of species are needed to reduce variability in ecosystem processes

53
Q

Yvon-Durocher et al., 2011

A

Body size of aquatic species decreases with an increase in temperature

Conservation Ecology (15 decks)

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