Lecture 19- Community change: Range shifts Flashcards Preview

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Flashcards in Lecture 19- Community change: Range shifts Deck (43):
1

What are the two types of expansion/contraction of a species' range?

•Expansion and/or contraction of a species range 1. Range shift=No direct human mediation= new area adjacent to old 2. Introduction = new area separated from old -directly mediated by humans

2

Were the Mediterranean and the Red Sea ever connected before the construction of the Suez Canal?

-yes, in the Pliocene, 2 million years ago

3

When was the Suez Canal opened?

1869

4

What is the functional significance of the Suez Canal?

-Removal of topographic barrier between two biogeographic provinces so can mix

5

Is the Suez a range shift of introduction?

- there is a human component but really it is mostly range shift as it is not a human mediated transport of organisms

6

How long, wide and deep is the Suez Canal?

-Length 193 km (164 km in 1869) -Max depth 24 m (8 m in 1869) --Width 123 - 313 m (65 - 98 m in 1869)

7

What are the intermediate water bodies on the Suez Canal and their salinity?

1. SE Mediterranean: Summer SST up to 29oC Salinity 39.5 ppt

2. Lake Timsah - brackish

3. Bitter Lakes - hypersaline early 1870s - up to 70 ppt 1970s - 43 to 48 ppt

4. Gulf of Suez Salinity up to 45 ppt -there is a difference in salinity in between the red sea and the mediterranean -big differences in salinity -brackish= less salty

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8

What is the current direction in between the Red Sea and the Mediterranean?

-Currents to north except July-Oct

9

What is the environment of the Med. vs Red Sea?

1.SE Mediterranean (Levantine Sea) a) sub-tropical Atlantic-Mediterranean province b) relatively depauperate biota (e.g. < 50% benthic spp of whole Med) c) oligotrophic 2.Red Sea / Gulf of Suez a) tropical Indo-Pacific province b) abundant & diverse biota (lot of endemism, derived from the indo-pacific province) c) very oligotrophic

10

What is the biota derived from in the Med and Red Sea?

1.Med:sub-tropical Atlantic-Mediterranean province 2.Red:tropical Indo-Pacific province

11

How is the cross canal migration called?

-Lessepsian migration = migration from Red Sea to Mediterranean via Suez Canal –over 300 species

12

How many species migrate in the direction from Med to Red Sea? Why?

-Few spp. in reverse direction –all confirmed migrants are fish = only active swimmers as the current goes north most of the time so have to swim against it to get to the Red sea

13

What are some examples of the Lessepsian migrants?

1:Penaeid prawns –bulk of catches along Egyptian coasts 2.Commercial fish species –␣ e.g. lizardfish Saurida undosquamis 3.Jellyfish Rhopilema nomadica –first seen 1980s –now huge swarms June/July – impacts fishing, tourism -------------------------------------- -almost 1/2 of fished species in SE Med. is from the species migrated from the Red Sea -this migration is a mixed blessing= good for fishing since more species but jellyfish are bad!

14

Is the transfer of organisms from Red to Med via shipping or aquaculture?

-only few tranported on hulls of ships= -Only 20% of Erythrean fish •Only 13% of Erythrean decapods •Only 12% of Erythrean molluscs --most are making their way by natural dispersal

15

What is the black urchin?

-Centrostephanus rodgersii •NSW species •Creates barrens on coastal reefs •First isolated specimens in NE Tas in 1978 •Over last 40 years, moved polewards at ~160 km / decade (-urchin use to reach souther limit in NSW -now even in Tasmania -moving to the South 160km/decade= rapid shift)

16

What do urchins feed on?

urchin barrens= lot of rocks= they graze on the rocks and eat everything (especially algae)

17

Why have the black urchins been moving southwards?

-Increased southward penetration of Eastern Australian Current over last 60 years -Eastern Tasmanian waters now warmer, saltier & lower in nutrients and can support the larvae that need 12C at least

18

What are the characteristics of the urchin larvae?

•Long-lived (~ 100 days)

• Min 12oC for successful development

•Sustained larval transport from NSW, not just chance dispersal event(s)

-can stay in the water column at a certain level thanks to the wings

-need 12C= now with the Eastern Australian Current it is further south where these temperatures are reached so they can disperse further

-sustained flow of larvae towards Tasmania, genetic diversity the same in Tas as NSW

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19

What does this graph show?

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-Barren= the bare rock grazed by urchins -have good populations in th enorth but as move south the age of populations declines -amount of barren decreases towards the south -so the urchins do less well in the south but still can survive

20

What is the Macrocystis pyrifera?

-ecosystem engineer -keystone species -forms huge kelp forests (up to 30m long)

21

What effect do the urchins have on the Macrosystis?

-Decline in Macrocystis pyrifera – urchin grazing –also increased temp & reduced nutrients -sea urchins graze off new recruits=so fewer individuals survive -increased temp and less nutrients= due to East Australia Current moving further south -its optimum conditions are cold nutrient rich water= now not as common

22

What is the whole flow chart of Macrocystic decline and the reasons for it?

-

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23

What are the general projections of change due to global climate change in temperature and pH?

-projections of what the temp and pH will be like in 2070

-increase in temp= mainly in the southeast part of australia -decrease in pH, the blue and purple is the most dramatic drop =influence on calcifying organisms= moluscs, corals and calcarious algae= won't be able to grow

-the temp and pH will make range shifts occur

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24

What is the projected change in sea temperature at 500m depth due to global climate change?

- warmed by 0.5 - 1.0oC

25

What is the projected change in incident solar radiation due to global climate change?

-more on surface waters (2 - 7 W/m2)

26

What is the projected change in mixed layer depth due to global climate change?

- greater stratification & shallowing of mixed layer by ~1 m, reducing nutrient inputs from deep waters

27

What is the projected change in surface winds depth due to global climate change?

-increased by 0 - 1 m/sec

28

What is the projected change in surface currents depth due to global climate change?

-general decline in strength of 1 m/sec

29

What is the expected impact on phytoplankton due to global climate change?

HIGH IMPACT -Species driven southwards

30

What is the expected impact on zooplankton due to global climate change?

HIGH IMPACT -Large southwards movements of species

31

What is the expected impact on seagrasses due to global climate change?

MEDIUM IMPACT -Shifts in species distribution southwards & alteration of species composition of beds

32

What is the expected impact on mangroves due to global climate change?

MEDIUM IMPACT -Shift in species distributions

33

What is the expected impact on kelp due to global climate change?

HIGH IMPACT -Distributions of kelp & other southwards but some imperilled by bounded coastline - limited in how much it can move southwards as need rocky shore and eventually stops

34

What is the expected impact on rocky reefs due to global climate change?

HIGH IMPACT -Large southwards movements of species

35

What is the expected impact on coral reefs due to global climate change?

HIGH IMPACT -Southward expansion but limited to several hundred km by carbonate availability

36

Will cold water corals be highly impacted by global climate change?

yes

37

What is the expected impact on soft bottom fauna due to global climate change?

HIGH IMPACT -Shift ranges of many species differentially so new assemblages

38

What is the expected impact on benthic/demersal fish due to global climate change?

HIGH IMPACT -Southward shifts but some declines where ranges bounded to south

39

What is the expected impact on pelagic fish due to global climate change?

MEDIUM IMPACT -Species moving southwards

40

What is the expected impact on turtles due to global climate change?

HIGH IMPACT -Range expansions may occur to south

41

What is the expected impact on seabirds due to global climate change?

MEDIUM IMPACT -Distributions expanded/shifted southwards

42

What are the main impacts of global climate change on the biota?

predominant impact is that they are driven southwards -if on reefs or rocks= they might go extinct as there won't be where to move

43

WHat happened since 2006 (the prediction)? Is it happening?

•Early 2011 - marine heat wave –Sea temps along most of west coast 2 - 4°C warmer – Changes in seaweeds, sessile invertebrates, demersal & pelagic fish Halophila ovalis •300 km range extension southwards of tropical seagrass Halophila minor (Moreton Bay) •Southward range extensions for many coastal temperate fish. •Increased reporting of tropical pelagic fish from southern waters. -so yes, it is happening -heat wave for months= 2011 -impact on many species,coral bleaching, manta rays much more south -each are just an anecdotes but together indicate a pattern