lecture 3 ecology

Question 1

aquatic biomes, what is the key to distribution

Answer 1

the key is the levels of salinity. we have fresh (low salinity) – estuaries (mid salinity) and marine (high salinity)

Question 2

what does the estuaries act as

Answer 2

it acts as a barrier between the fresh water and saltwater. many organisms cannot cross this barrier, however salmon can

Question 3

what is the depth of the ocean

Answer 3

it is an important structuring factor

Question 4

what does depth affect

Answer 4

temperature and light levels. (the deeper you go the darker and colder it gets).

Question 5

what is another thing that separates the ocean

Answer 5

the distance to shore (intertidal, neritic, oceanic)

Question 6

intertidal

Answer 6

close to shore, between low and high tides – mostly exzposed to air

Question 7

neritic

Answer 7

near shore zone

Question 8

oceanic

Answer 8

off shore

Question 9

depths on the ocean

Answer 9

photic, aphotic, abyssal, pelagic, mesopelagic, benthic, continental shelf

Question 10

photic zone

Answer 10

99% of the light around this zone, top 200m – where photosynthesis happens, therefore all photosynthesizing organisms live here.

Question 11

aphoticx zone

Answer 11

1% of light – beyond light, res of the depth.a

Question 12

abyssal zone

Answer 12

deep deep ocean – very food limited.

Question 13

pelagic zone

Answer 13

the water column, basically all zones tg

Question 14

mesopelagic

Answer 14

200-1000m – intermediate, the twilight zone. entire marine food web lives in this zone

Question 15

benthic

Answer 15

seafloor – corals attached to the floor

Question 16

continental shelf

Answer 16

shallow region

Question 17

different zones summary

Answer 17

benthic vs pelagic – seafloor vs water column
photic vs aphotic – light vs no light
intertidal vs neritic vs oceanic – shore vs near shore vs offshore

Question 18

Lakes – structre

Answer 18

similar to oceans in depth (photic (more shallow than ocean), aphotic, benthic (lake floor), pelagic(water column)). however distance to shore is diff (naming wise) – Limnetic (open lake (far offshore)) – littoral (close to shore line)

Question 19

what are aquatic environments in terms of nutrients

Answer 19

nutrien limited – not much productivity. `

Question 20

what does stratification do / describe

Answer 20

it controls the nutrient availability – basically how ‘fixed’ the water column is.

Question 21

stratified lake – description

Answer 21

layers sitting on top of each other – not much mixing due to differing densities

Question 22

Lake stratification (summer)

Answer 22

in the summer – we have 2 layers – warm and cold – the warm layer : is photic, photosynthesis occurs, it is oxygen rich but nutrient poor because all the nutrients are being used for photosynthesis– the cold layer is: aphotic, oxygen poor because no photosynthesis and nutrient rich because not as many organisms are present so it is not used up.

Question 23

why are there two layers in the sumer

Answer 23

because of the thermocline – this is why they dont mix. this is the zone of rapid temperature change, also known as the gradient of temperature. – the warmer water is less dense so it floats ontop of the colder, more dense water.

Question 24

lake stratification (fall)

Answer 24

the surface water in the lake cools down – thermocline breaks down therefore no more temperature gradient – this means the water at the surface is getting more dense – eventually surface water will get to sae density, or higher as the bottom layer and they will mix – bottom layer brings up nutrients and top layer will bring down oxygen.

Question 25

lake stratification (winter)

Answer 25

the thermocline will reappear but it will be a different temperature gradient (colder on top then on bottom) -- fresh waters max desnity is at 4ºC this is the bottom layer -- top layer is frozen at 0ºC

Question 26

lake stratification (spring)

Answer 26

surface will start warming up until it is the same density as the bottom layer -- mixing happens again-- and bottom will bring nutrients, top will bring oxygen--

Question 27

open ocean stratification overview

Answer 27

thermocline rapidly drops off --surface temp = 20ºC bottom = 5ºC -- seasonality plays a role -- temperature in temperate regions. -- thermocline will need to breakdown for nutrients in fall and winter.

Question 28

eutrophic

Answer 28

high nutrient -- high productivity -- temperate, seasonal

Question 29

oligootrophic

Answer 29

low nutrients -- low productivity -- no thermocline breakdown to re introduce nutrients. -- tropical systems

Question 30

shallow water marine habitats, examples

Answer 30

kelp forest, coral reefs (a lot of species packed in small area), intertidal (barnacles; sometimes exposed to air, sometimes water)

Question 31

interspecific interactions (between species)

Answer 31

competition, mutualism, predation/herbivory/parasitism, commensalism

Question 32

competition species 1 and 2

Answer 32

both are negatively affected in terms of population growth rate -- each species is competing for the same thing, therefore both will get less of it -- consequence is reduced growth rate.

Question 33

mutualism species 1 and 2

Answer 33

both positively affected in growth rate -- two species interact in a way that benefits both of them

Question 34

predation/herbivory/parasitism species 1 and 2

Answer 34

positive for one, negative for the other win for one species, loss for another - -example is when herbivores graze gass, plus on herbivores (FOOD) loss on grass (negative growth rate)

Question 35

commensa;lism species 1 and 2

Answer 35

positive on one, and no affect on other -- very rare to find in. nature

Question 36

competitiopn in the rocky intertidal

Answer 36

barnicles live in the intertidal zone

Question 37

barnicles line in intertidal -- explain high, mid, low

Answer 37

`high intertidal -- mostly exposed to air, mid intertidal -- middle low intertidal -- mostly covered by water

Question 38

barnicles -- what happens in intertidal

Answer 38

crowding happens, barnicles are pushed up against one another because of small strip of habitat

Question 39

interspecific competitors relative to intertidal

Answer 39

use same resource -- competiing for same reosurce (space) -- resource is limited in supply

Question 40

competition leads to .. b..d..r.

Answer 40

lower birthh rates, higher death rates, and slower population growth

Question 41

barnicle bio

Answer 41

have both male and female sex organs, adults live on rocks, but larvae (early barnicles) are free swimming

Question 42

chthalamus

Answer 42

smaller, lives higher up the intertidal

Question 43

balanus

Answer 43

bigger, lives lower down the intertidal

Question 44

separation between chthlamus possible hypothesis

Answer 44

settlement pattern - -dispersal -- thats unlikely because larvae are free swimming so they are able to get anywhere each adapted to its zone, interspecific competition -- one species preventing the other to live in particular part of intertidal

Question 45

experiments were condsucted -- removeal 1

Answer 45

scraped away balanus in intertidal and compared w control group of balanus. -- mid experiment - chthalamus settled in both areas (cleared and with balanus) -- end experiment -- chthalamus nearly gone in balanus crowded area, but persisted in empty, scraped away area. -- identified that competition was what was going on -- Balanus EXCLUDED Chthalamus as it is a bigger competitor

Question 46

removeal 2

Answer 46

further up the shore line -- scarped away chthalamus, and compared to control group of chthalamus mid exp -- balanus settles end exp -- balanus dies in both areas -- concludes that adaptations are also a result for the pattern -- Balanus is better suited in more submerged water areas. Chthalamus does NOT exclude Balanus because it is not outcompeting, it is just better adapted to drier environments.

Question 47

Conclusions of both experiments

Answer 47

both species CAN coexist as long as different exposure to air and water -- diff parts of intertidal -- in the lower intertidal -- chthalamus is outcompeted by balanus -- in the upper intertidal -- balanus is excluded by physical factors (drying out) due to adaptation

Question 48

what can both balanus and chthalamus occupy then

Answer 48

different niches

Question 49

what is a niche

Answer 49

set of conditions an organism can survive and thrive in (like bees and pollination) (position of a species within an ecosystem)

Question 50

there are two types of niches

Answer 50

realized and fundamental

Question 51

realized nuche

Answer 51

where you see organisms in the wild, -- may be constrained by competition (otters in lakes and streams because in larger bodies of water more predators) ALWAYS ≤ FUNDAMENTAL

Question 52

Fundamental niche

Answer 52

absence of competion or other biotic factors -- range of cxonditions in which it can survive and reproduce (ideal conditions) ALWAYS ≥ REALIZED

Question 53

Balanus -- terms of realized vs fundamental

Answer 53

R=F -- grwoing where it can survive -- it is not being constrained by competition

Question 54

Chthalamus -- termins of realized vs fundamental

Answer 54

R

Question 55

Competitive exclusion principle

Answer 55

if two species compete for one resource, the bettewr competitor will eliminate the other, if they have same niche, one will go towards extinction. -- species must occupy somewhat different niches,.

Question 56

Coral reefs introduction (distribution etc.)

Answer 56

very high species diversity, (fishes, corals, invertebrates) distribution -- shallow waters, tropics and sub tropics, and temperatures at around 18-30ºC

Question 57

Coral biology

Answer 57

Corals are formed of polyps-- they are restricted to shallow coastal tropical waters -- have abundant light but are nutrient poor (oligotrophic) -- corals are TWO THINGS living together in symbiosis

Question 58

what are the two organisms that make up coral (live together)

Answer 58

polyps and zooxanthellae

Question 59

polyps

Answer 59

small animals that live in colonies -- protected by hard calcium carbonate skeleton -- the skeleton forms the strcuture of the reef. `

Question 60

zooxanthellae

Answer 60

photosynthetic eukaryotes (microscopic algae) -- give the coral its colour, and gives polyps source of food.

Question 61

give rough sketch of coral

Answer 61

tentacles, algae within tentacle, little squiggles is the polyps

Question 62

what is symbiosis a form of

Answer 62

mutualism -- interactions between species benefits them both

Question 63

what are both organisms (polyps and zooxanthellae)) getting out of symbiosis

Answer 63

Polyps: zooxanthellae photosynthesize therefore produce carbohydrates and feeds the polyps (they take 90% of the products) zooxanthellae: they can live outside the corals, but they choose to live inside because the polyps excrete waste in the form of O2 and N which are nutrients need for more photosynthesis. They also choose to live in corals because it is safer, and keeps them away from predators.

Question 64

coral reefs are changing

Answer 64

coral cover has decline dramatically in many parts of the world -- carribean ~50% cover in 1970s and now ~10%. in 2000s' the reefs are switching from reef/coral dominated to macroakgae dominated

Question 65

what do macroalgae do to dominate

Answer 65

they choke/smother the corals and therefore outcompeting the corals as they grow really fast. (in hiogh nutrient conditions) intersepcific competition (space) disturbances open space on reef like (diseas, storm, coral predators) and that space is reoccupied by the macroalgae.

Question 66

thew sepcies that gets to persist dsepends on a few things :

Answer 66

settlement rate -- how fast are macroalgae spores coming in, or how fast is the rate that coral larvae settle onto thje space. growth rate -- rate that colonizing organisms can grow

Question 67

what changed in the carribean?

Answer 67

birth and growth rates influenced by the biotic and abiotic factors OVERFISHING -- decline in large herbivorous fish (parrotfish) -- these fish feed on the macroalgae and keeps its abundance down -- another herbivore took its role (diadema) (sea urchin) and grazed the macroalgae to limit them -- massive die off of sea urchin occurred in 1983(possible due to disease) -- then macroalgae bgan to takeover -- without thesew herbivores macroalgae outcompete corals as they are more superior

Question 68

other factors that might have increased abundants of macroalgae

Answer 68

`increased coral disease rates -- tissue loss and discolouration -- eventually die off)\ sewage and agriculture run off -- high nutrient levels enhance the macroalgal growth NOT coral as coral is adapted to LOWER nutrient environments. warm temperatures -- coral bleaching -- polyps expel zooxanthellae because it gets too hot, this means loss of food, will turn white then eventually die.

Question 69

key points

Answer 69

environment affects the outcome of competioton (abiotic and biotic) -- mechanism -- effects on bith, deatt, and growth rates. communities have a complexitiy of species interactions (interspecific competition, herbivory, predation, mutualism `

Question 70

critical points

Answer 70

rebundancy can increase the resilience of a community

Question 71

rebundancy

Answer 71

multiple species fulfilling the same role -- can lose one species and still be okay

Question 72

resilience

Answer 72

ability to bounce back / recover after a disturbance has improved

Question 73

management (our control)

Answer 73

- marine protected areas (herbivore fish) - clean up of nutrient inputs in coastal wayters - mitigating threat of climate change.