Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EEMB 147 > Midterm 3 > Flashcards

Midterm 3 Flashcards

1
Q

Tropical marine seascape

A

-mosaic of habitats: mangroves, sea grass beds, coral reefs
-buffering sediments from land/rivers
-some movement of organic matters
-nurseries and foraging grounds
-metaecosystem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mangroves

A

-terrestrial flowering plants have reinvaded the sea
-mangrove-individual plants
-mangrove forest, mangrove swamp, tidal forest, or mangal (community that is made of mangroves)
-65-70% of tropical coastlines have had mangrove forests
-high tide=roots under water
-throughout the tropical and subtropical oceans of the world

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Prop root communities

A

-Epifauna on submerged roots->sponges, oysters, algae
-many filter feeders
-concentrate pelagic production on create N rich wastes
-lots of nutrients, inverts, and organic matter -> food for fishes
-Mutualism: mangroves provide shelter, epifauna provide N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sea grass

A

-submerged flowering plants
-typically prefer shallow clear water (<3m->30m deep)
-they grow close to shore in many costal regions
-colonial plants form extensive beds
-clonal plants that grow thru vegetative elongation
-live very long lives, extended over very large areas
-rhizome: horizontal growth, with vertical offshoots
-mimics distribution/diversity of coral reefs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Importance of rhizomatous growth

A

-foundation species (facilitates diversity of algae and other fishes)
-create 3D habitat
-stabilize sediments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a nursery habitat?

A

-habitat used by juveniles before moving to adult habitats
-positive effect on density, survival, growth, and/or movement of juveniles bc of food resources, predator avoidance or larval trapping
-high food/low predation most likely benefits (lower abundance or smaller predators)
-both fish and invertebrates - not all species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the dynamics of nursery habitats?

A

-pelagic phase: egg/larval phase in open ocean
-benthic phase: juvenile/adult phase in benthic habitats

Open ocean->mangroves->reef->back to open ocean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Detection of cues specific to nursery habitats

A

-water from sea grass and mangroves probably contains different chemical compounds
-differences detected by fishes
-using multiple cues
-juveniles prefer sea grass/mangroves over reefs (don’t discriminate between the two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the density of species in mangroves and sea grass beds?

A

-generally have high densities of juveniles-> but not always true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sea grass beds as nurseries

A

protection from predators
-mobile predators have harder time foraging
-ambush predators (seahorse have easier time)

More food and faster growth
-lots of organic matter, small intertebrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do fish avoid predation in mangroves?

A

-could be habitat complexity (place to hide) or shade (more difficult to see)
-tested by using artificial mangrove units
results: specific to species
-grunt spp: impacted by structural complexity and shade
-snapper spp: only affected by shade, abundance of spp isn’t affected by habitat complexity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where is predation pressure highest?

A

-more predation pressure on coral reefs compared to mangroves/seagrass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why may seagrass and mangroves might not be optimal for growth?

A

-growth rate of fish may be higher on reef, but higher predation risk-trade-off
-suggests that predation is main function of seagrass and mangroves is to avoid predation

-significant increase in biomass of grunt on patch reefs (2667%) (less susceptible to predators)
-smaller increase in shallow fore reef (659%)
-55% higher on forereef
-association with mangrove forest=increase in grunt population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are juvenile rainbow parrotfish dependent on mangroves?

A

-juveniles only seen in mangroves
-adults not seen at mangrove absent sites
-local extinction after removal of mangroves (have to go straight to patch reef, more susceptible to predation bc they are smaller)
-loss of single rainbow parrotfish would constitute a 10% reduction in total parrotfish biomass within its territory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Detritus nutrients exchange

A

Mangrove leaves
-can be dissolved or particulate
Detrital transport via physical process
-importance of tidal flow/currents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ontogenetic nutrients exchange

A

Movement of animals as they grow
-mangroves/seagrass as nursery habitats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Trophic relay nutrients exchange

A

Series of predatory-prey interactions
-different fish use shallow foraging grounds differently
-migrate 1 ecosystem to the next
-happens within day, as opposed to ontogenetic migrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does connectivity of habitats affect nutrient exchange?

A

High connectivity: optimal foraging, refuge, and ontogenetic transitions

Medium: optimal foraging for adults only, high mortality for transitioning juveniles

Low: sub-optimal for both juveniles and adults due to energetic constraints and predation risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How important is organic matter in mangroves/sea grass

A

-very important source of carbon
-up to 50% for sponges, 40% for corals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Sediment trapping by mangroves and sea grass

A

-rivers have large sediment load
-once sediments are trapped in mangroves, waters slow
-also traps sediment in incoming tidal water
-also trap pelagic larvae (allowing them to explore and find a good place to settle)

High mangroves = high corals (mangroves buffer sedimentation, resulting in clear water at the coral reefs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do seagrass beds remove pathogens?

A

Fecal contamination
-seagrass filter out contaminants
Experiment:
-removal of seagrass=higher prevalence of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

‘Commuters’ using foraging grounds

A

-organic matter moves btwn habitats in the form of fish (other than nursery function)
-transfer nutrients from 1 ecosystem to the next
-ex: fish enter mangroves/seagrass periodically to feed
-adult yellowtail snapper lives on the reef and enters mangrove to feed at night

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Types of commuter

A

-snappers: carnivorous, schooling, feeds on fish and crustaceans
-grunts and sweet lips: more elongated, heavier body, nocturnal feeders, mainly invertebrates, large schools

strongly associated with abundance of seagrass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Migratory fish schools

A

-restlessness: individuals roll bodies agitatedly
-assembly: school tightens, moves to a staging area near the edge of the reef
-ambivalence: individuals darting out along the path and returning to the reef
-migration:school departs the reef->moves up to ~500m

Feed at night in seagrass/mangroves
Migration routes culturally transmitted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Fish schools and nutrients hotspots

A

High fish biomass sites= 10x more N and P
nutrient hotspots attract herbivorous fishes
-increases in herbivory prevents strong increase in macroalgae at hotspots (higher average bites per minute)
-results in an increase in coral growth (75%) at hotspots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How are fish schools an asset to corals?

A

corals with aggregations of resident grunts
-30% more tissue mass
-25% more tissue N
-29% more zoozanthellae
-70% higher growth rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Seabirds and coral reefs

A

-seabirds aggregate in very high densities
-catch food in open ocean and move nutrients and terrestrial sediments to reefs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Palmyra Atoll

A

-Native (N) vs Palm (P) forests
-abundance of birds was higher with native forests than palm
-native forests had higher N, zooplankton, more nutrients
-more manta rays in native forests due to increasing zooplankton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Chaos Archipelago

A

High rats=low seabirds
-less nutrients are imported to the reef because of the decrease in seabirds

Island without rats
-damselfish grow faster (more nutrients)
-more herbivorous fish
-higher bio erosion and herbivory
-different algal communities (CCA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Tetiaroa Atoll Restoration Program (TARP)

A

Successful restoration program that eradicated rats on the Tetiaroa Atoll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Sucessful Invasion of Spp

A

-Vectors:Organism introduced to new habitat (intentional introductions, boat propellers, underbelly of ships)
-frequent invasion: repeated introductions/vectoring events
-ecological compatibility: survive abiotic template and exploit resources-> good invaders, likely generalists, withstand lots of habitats and stresses
-survival of initial population bottleneck: small population, low genetic diversity -> need rapid local population increases, disturbance many allow low level invader to take over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What makes an invasive species invasive?

A
  1. introduction:organism has to overcome a major geographic barrier (via human interactions). However, these fail to maintain populations over long periods of time
  2. naturalization:local environment (biotic and abiotic) and reproductive barriers are overcome and regular reproduction occurs
  3. invasion: overcome dispersal barriers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Deep (mesophotic) reefs

A

-deeper sections (below 30-40m)
-down to 150m
-upper vs lower mesophotic - transition
-still has photosynthetic organisms
-buffered from major bleaching and storm events, lower disturbance rates
-community similarity btwn shallow and deep decreases with depth
-very bottom of light range
-larger eyes, organisms are more red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are important physical gradients?

A

-low light and wave exposure- minimal temp gradient
-relatively high nutrients
-corals tend to have ‘plate’ morphologies to gather light/limited wave exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Fish/benthic assemblages in mesophotic reefs

A

-fewer herbivores (low primary production),high planktivores
-distinct fish assemblages upper vs lower
-upper:spp that exist in shallow and deep water
-lower dominated by 2 mesophotic specialists (filterfeeding)
- 30-40m: turf algae, fleshy macro algae and corals
-40-90m: bryozoans, black corals and sponges
-endemism: only exists in specific location

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Endemism

A

MCE: mesophotic coral ecosystem
-species that are limited to a specific area
-higher endemism in mesophotic reefs, compared to shallow reefs
-increases with latitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How do you sample mesophotic reefs?

A

Mostly in situ
-remotely operated vehicles (ROVs)
-rebreather diving
-ARMS: autonomous reef monitoring structure

Deeper reefs host significantly different brachyuran communities, and have a much lower total abundance
-4-27 unique morphospecies per depth
-3 out of 69 morphospecies across entire depth range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Deep water corals adaptations

A

-increased heterotrophy, more energy from eating zooplank
-reduced energy requirements
-still have photosynthetic symbionts, which are morphologically different from shallow coral symbionts-> more efficient at photosynthesis
-leptoseris: lower photosynthetic pigment concentration
-chlorophyll b isn’t produced by symbionts->strong relationship with endolithic algae (low light adaptation)
-superior light harvesting comes from skeletal morphology, not pigment concentration-> lets in light and allows it to bounce around the coralite (reflects light) and maximizing photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Connections to shallow reefs

A

-manta rays travel between shallow and mesophotic reefs and moves nutrients back and forth
-upper 10m during the day
-deeper water throughout the night to feed
-role as an ecological link btwn epipelagic and mesopelagic habitats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Function of mesophotic reefs as buffers from disturbances

A

-possible serves as refuges for corals to recover after disturbance
-unexpectedly large areal extent of mesophotic reefs
-it is important to understand the connectivity across the depth gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Deep water refuge hypothesis

A

-deep reefs proposed as refuges against major disturbances affecting shallow reefs
-they provide coral propagules to aid in shallow reef recovery
-primarily upper mesophotic depths (30-60m) -> deep enough to escape disturbances but shallow enough to have overlap in species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Coral evidence for deep water refuge hypothesis

A

Brooding species (Agaricia fragilis): depth-associated genetic differences in the brooding spp (different populations)
-connectivity over ecological time scale is limited
-didn’t exchange genetic material

Broadcasting spp (Stephanocoenia intersepta): no genetic structuring btwn depths (same populations)
-substantial potential for vertical connectivity
-did exchange genetic material

Reseeding potential of deep reefs may apply to only a small number of spp (<25% of corals)

43
Q

Fish evidence for deep water refuge hypothesis

A

> 60m lack of live coral habitat
70m majority of fisheries spp found from shallow
Mesophotic reefs fish>MPAs
Mesophotic depths essential fish habitat and refuge

44
Q

What are the effects of sedimentation on corals?

A

-water clarity is key for photosynthesis and coral health
-high levels of sedimentation=low water clarity and low photosynthesis

45
Q

How do corals deal with sediments?

A

Mucus entanglement, ciliary action, tentacular manipulation
-comes at an energetic cost->less energy for coral maintenance
-increase energy to shed sediments->mucus production
-sedimentation can directly kill corals
-sediments create spaces of mortality where they settle on the coral

46
Q

How does sedimentation impact coral recruitment?

A

-suppresses coral recruitment and replenishment of coral larvae

47
Q

How do sediments impact herbivorous fishes?

A

-sediments bound in algal turfs suppresses herbivory
-positive feedback on algal growth
-negative feedback on corals

Increase sediment=suppression of herbivory = increase algal growth

48
Q

Do chemical sunscreen impact corals?

A

-oxybenzone on coral larval survival
-at high concentrations oxybenzone does affect the morphology of coral larvae and it begins to calcify
-at very high concentrations the larvae die
-increases bleaching, decreases PS
-increases DNA damage in larvae ->genotoxicant
-causes larval deformation-skeletal endocrine disrupter
-the concentrations tested were similar to concentrations seen in the ocean

49
Q

Does zinc sunscreen impact corals?

A

-zinc oxide has been found to be more harmful to coral photo systems than chemical sunscreens
-zinc oxide causes coral bleaching ->symbiosis breakdown
-unsure if the concentrations of zinc tested matches the concentrations seen in the ocean
-titanium oxide = minimal impact to corals

50
Q

How does nutrients impact corals?

A

-corals usually do well in waters where inorganic nutrient concentrations are low
-more ammonium (NH4) = faster coral growth
-ammonium vs nitrate
-corals don’t have the mechanisms to use nitrate, they can’t regulate it->symbiont is less reliant on coral
-amount of chlorophyll in cells is increased by ammonium in zoozanthellae->significantly more with ammonium->makes symbionts more effective
-ammonium coals send more C back to corals

51
Q

Why does the type of nitrogen nutrient matter?

A

-nitrate exacerbated bleaching prevalence and duration in Acropora
-nitrate tripled coral mortality in Pocillopora (symbionts are more selfish, less willing to give corals carbon
-no effect of urea
-nitrate=human-derived
-urea=fish derived

52
Q

How does nutrients impact disease severity?

A

Nutrients increase disease severity
-increase in tissue loss-> more susceptible to disease and heat stress
-disease progresses faster when nutrients are added

53
Q

Kaneohe Bay

A

-partially enclosed Bay
-few inhabitants until 1930s
-high biodiversity and large % of coral color
-Kaneohe Marine Corps Air station released sewage into the bay (5 million a day)
-nitrate major N type in sewage

Results: large decline in coral cover and large macroalgae bloom
-phase shift from coral dominated to algal dominated
-the area recovered once sewage outflow stopped
-sewage also caused disease in fishes

54
Q

Bikini Atoll

A

-23 nuclear tests
-water to 55,000 degrees C
-shock waves to 70m deep
-completely decimated the area of corals

Present Day: ~150 spp
-if we leave reefs alone, generally they can recover

55
Q

Coral disease

A

-one of the most pressing issues in reef deterioration and coral mortality
-fast emergence, high virulence, widespread distribution
-30% of corals worldwide lost to disease during the last 30yrs

56
Q

Where is a disease hot spot?

A

Caribbean
Combination of:
-density of human population
-temp
-coral diversity is lower in the Caribbean
-low herbivore biomass and richness
-high rates of algal growth

57
Q

Why are coral diseases important?

A

-responsible for the significant reduction in coral cover
-70s: coral cover was 40-60%
-2002: <10% coral cover

58
Q

White band disease

A

-1980s: white band disease killed majority of Acropora in Caribbean
-up to 98% of Acropora in Caribbean disappeared
-resulted in a transition from Acropora to Agaricia
-1980s and before: Acropora was dominant
-1990s to present: Agaricia was dominant

59
Q

Stony Coral Tissue Loss Disease

A

-‘new’ disease as of 2015
-started in Florida and spread throughout the Caribbean
-agent is unknown, but likely bacteria->responds to antibiotics
-rapid spread
-rapid coral mortality
-affects up to 25 coral spp
-high prevalence: up to 100% of colonies of some spp, typical disease prevalence in 5-10%, kills in weeks to months

60
Q

What are in field challenges to characterizing coral disease?

A

-rare and patchy nature of the incidence of disease
-difficulty of in situ distinction btwn disease tissue loss and other mortality, and distinguishing btwn other diseases

61
Q

What are in lab challenges to characterizing coral diseases?

A

-difficulty culturing potential pathogens from marine environment
-difficulty isolating pathogens and reinfecting to show causative agent
-difficulty in providing genetically uniform experimental animals for infection and transmission studies
-complexity of coral holobiont
-deficient understanding of coral defenses

62
Q

Black band disease

A

-1st reported coral disease
-worldwide distribution now reported (1st Caribbean, now in Indo-Pacific)
-<2% of population affected
-significant relationship with H2O temp and nutrients -> more pathogenic
-causative agent: beggiatoa
-Cyanobacteria, gliding bacterium with sulfur incisions, sulfate-reducing bacteria, other bacteria, fungi

63
Q

Aspergillosis

A

-fungal disease that has been affecting gorgonians since 1980s
-causative agent: Aspergillosis sydowii
-spores germinate on coral surface and hyphae penetrate and spread in coral tissue
-once infected coral tissue can’t be used to filter feed, tissue becomes hardened
-primary and secondary infections
-coral response: gall that encapsulates fungus
-A. Sydowii may not be the only pathogen

Where did it come from:movement of dust storms from Sahara desert, moving terrestrial organisms or Orinoco river plume (sediments with fungi get trapped in corals)

64
Q

White Pox aka acroporid serratiosis

A

-aka patchy necrosis
-causative agent: Serratia marcescens (common fecal enterobacterium)->associated with waterborne infection in tropical waters and hospital-spread infections
-often present in sewage
-Corallophila abbreviata: a corallivorous snail that is a reservoir and vector of S. marcescens->holds bacteria in mouth and passes it from coral to coral

65
Q

White Plague Disease

A

-Florida’s mystery coral-killer identified
-bacterial disease
-genus of causative agent: Sphyngomonas
-Denner IDed new genus and species as Auratimonas coralicida

66
Q

What is the current status of coral diseases?

A

-40 diseases reported worldwide
-only 9 with identified pathogens

67
Q

What factors influence coral disease?

A

-bleaching
-nutrients
-plastics
-tourism/breakage
-fishing

68
Q

How are bleaching and coral disease related?

A

-high temps and bleaching can leave corals more vulnerable to disease
-can quickly kill part or all of the coral colony
-lag effect (bleaching 1st, disease 2nd)

69
Q

How do nutrients impact the disease severity?

A

It increases severity by increasing the stress of the corals
-corals with yellow and and aspergillosis experienced more tissue loss with added nutrients

70
Q

How do plastics impact coral reefs?

A

Plastics increase coral disease
<10% disease prevalence for corals without plastic
~100% disease prevalence for corals in contact with plastic
-massive and branching corals are most affected by
-vectoring new microbes into corals
-physical interaction of plastic with corals

71
Q

How does tourism impact the spread of coral disease?

A

Increased interaction with tourists=increased coral breakage
-more susceptible to coral disease by increasing their stress

72
Q

How does fishing impact the spread of coral disease?

A

MPAs vs fished area
-more disease in regularly fished areas
-there is a positive relationship between diseases and butterflyfishes
-removal of butterflyfish predators=higher butterflyfish population=increase abundance of disease bc butterflyfish act as a vector

73
Q

Global warming

A

-increased CO2 level->increased greenhouse gas->increased sea temperature->increase coral stress and bleaching

74
Q

What happens inside a coral cell during bleaching?

A

-CO2 becomes limiting (carbon limited)
-energy from sunlight must go somewhere
-reactive oxygen species (ROS): damage cellular mechanisms of corals
-light and heat interact to drive bleaching
-bleached corals are not dead->they will starve to death if they do not recover their symbionts

75
Q

Galapagos-El Nino event in 1982/83

A

-temp of water = very warm
-nearly 100% mortality of corals—from coral dominant to coral depauperate system
-system becomes dominated by macroalgae

76
Q

Global bleaching history

A

1997-98
-worst global bleaching on record
-all ocean basins
-strong El Niño/La Nina cycle
~16% of global reefs say almost complete mortality
-El Nino in Indian Ocean (1998): 80-90% of corals bleached and died, 20% of corals died worldwide

77
Q

Typical Pacific Ocean water circulation

A

-wind moves from east to west
-drives equatorial currents
-drives strong up welling in East Pacific (cold water moves from deep to surface)
-high pressure in east, low pressure in west
-higher volume of water in west compared to east
-warmer water in west, cooler in east

78
Q

El Niño Souther Oscillation (ENSO)

A

-slower winds
-slower equatorial currents
-no longer have upwelling in east and high water levels in west->these levels that were in the west, migrate to east and warm the whole Pacific

79
Q

Winners and losers in coral bleaching

A

winners: slow growing, encrusting corals
losers: faster growing, branching corals
-less tissue = lower survivorship
-more tissue = more photoproductive, more energy reserves
-differing symbionts
-bleaching can also reorganize communities

80
Q

Degree Heating Weeks (DHW)

A

One week at a time 1 degree C above summer average max temp
-average max at Moorea = 29, then 1 week at 30= 1 DHW
-takes into account intensity and duration
-2 DHW = 1 wk staying at 2 degrees OR 2 wk at 1 degree
-DHW over 4 C= significant coral bleaching
-DHW over 8 C = widespread bleaching and some mortality

81
Q

Coral mortality linked to DHW exposure

A

DHW <8 = all good, very little coral mortality
DHW >8 = die

82
Q

How did views change on causes of coral reef decline?

A

1994: humans pressures = larger threat than climate change
2000: climate change = larger threat than human pressures

83
Q

El Niño in 2015-16

A

-one of the strongest El Niños on record
-a mass bleaching event followed
-bleaching events are becoming more intense and more frequent
-frequency now= 4-6 years

84
Q

GBR and sources of coral mortality (prior to worldwide mass bleaching event)

A

-GBR—decades decline in corals-over 50% loss
-coincident with COTS outbreaks increase in bleaching
-most mortality came from COTS and cyclones

85
Q

Worldwide Mass Bleaching event

A

-2014-2017
-started in Republic of Kiribati, Kiritimati Island (2013)—in the very middle of alter 2 (most severe bleaching)
-in 2016: 90% coral loss

86
Q

GBR Disaster

A

-mass bleaching GBR 2016 (most severe)
-cyclone Winston saved South GBR by mixing up water and cooling it down, also making the water more turbid and cutting down on light intensity
-increase in DHW=increase in coral bleaching (very strong correlation)
-estimated at least 50-60% coral loss in North GBR->some reefs had over 90% loss
-areas became dominated by macroalgae

87
Q

How are fishes impacted by coral bleaching?

A

-75% of fish spp declined
-50% declined by less than 50%
-coral bleaching most affects the fish that are most associated with corals
-1998 bleaching event: cryptobenthic fish community changes after bleaching ,75% of Acropora and 100% of Montipora
-no change in fish spp richness/diversity (# of types of fish didn’t change)
-winners: generalist planktivores (damselfish rely on food from open ocean, not super dependent on corals)
-losers: coral specialists (gobies strongly depend on live corals)

88
Q

How are fish more susceptible to predation on bleached/degraded corals?

A

-corals physical structure doesn’t change when bleached
-they visually change (lose color), making it easier for predators to see the prey

89
Q

How does thermal stress impact the rapid onset of fish disease?

A

-Eliat, Red Sea
-fish were infected with streptococcus iniae (a bacteria)
-fish started dropping dead (ocean floor was covered with dead fish)
-piscivores and grazers seemed to be the most susceptible
-rapid increase in sea temp, compromised fishes’ immune system, making them more susceptible to infection

90
Q

Acropora distribution in Florida

A

-Holocene: temperature was increased, Acropora distribution was more north
-present day: temperature was decreased compared to Holocene, Acropora distribution was more south
-recently Acropora have been discovered in the north due to the increase in sea temperature

91
Q

Tropicalization of Temperate Habitats

A

-range shifts moving water water spp poleward
-many herbivores follow, migrating towards temperate reefs
-alter herbivores-algal interactions, migration of herbivores to temperate
-increase in herbivores and water temp (macroalge doesn’t have defenses against tropical herbivores)
-ideal place for coral larvae to settle, little compatition from algae

92
Q

Resilience vs Resistance

A

Resilience: ability of a population to recover after suffering a disturbance
Resistance: ability of a population to withstand a disturbance

93
Q

Coral-algal phase shift

A

Coral reefs shifting from a coral dominant ecosystem to a macroalgae dominant ecosystem

94
Q

What are sources of coral mortality?

A

Natural:
-huricanes/cyclones/typhoons
-COTS
Anthropogenic:
-bleaching
-disease
-sedimentation
-dynamic fishing
-ship grounding

95
Q

Hurricanes

A

-wave energy greatest in shallow water
-reef crests seriously affected (branching corals)
-may facilitate asexual reproduction—fragments from colonies
-impacts down 20-30m and occasionally 50m

Damage:
-colonies shatter, fragments damage neighbors
-deeper corals are damaged by shallow corals ‘falling’
-bioerosion weakens colonies, increasing hurricane damage
-tissue damage from sand scouring
-secondary mortality (disease, predation)

96
Q

What processes allows for coral resilience?

A

-herbivores often control macroalgal growth
-reduces abundance of magroalgae
-whether magroalgae develops depends on grazing pressure
-macroalgae can overgrow adult corals (but rare)
-macroalgae can increase after coral mortality (extra space to colonies)
-macroalgae prevents coral recruitment

97
Q

What factors contributed to the low coral cover on Jamaican coral reefs?

A

-decades of overfishing
-Hurricane Allen (1980)
-sea urchin disease —causing high urchin mortality
-Hurricane Gilbert (1988)
-White band disease on Acroporids

98
Q

3 phases of degradation (A-B-C)

A

A)healthy reef (high fish, modest urchins, coral dominated)
B)semi unhealthy reef (low fish, high urchins—herbivory is maintained, moderate coral-algae ratio)
C)unhealthy reef (aka modern-day Jamaica) (low fish and urchins, high algae, low coral)

99
Q

Continuous phase shift

A

-For given environmental conditions only 1 state possible
-relatively easy to move from one state towards another

100
Q

Discontinuous phase shift

A

For given condition, could be either state
-takes big change of conditions to make state change significantly
-very hard to move it back
-‘flip and lock’
-alternative stable state
-‘unstable’ btwn states, so state heads towards one or the other

101
Q

Draw the phase shift of a low resilience and high resilience reef

A

Low resilience: small disturbance drives shift to algal state
High resilience: high herbivores, can withstand more frequent and larger disturbances

102
Q

Positive and Negative feedbacks of phase shifts

A

Draw diagram

103
Q

How does the number of disturbances affect the likelyness that the reef will recover?

A

An increased number of disturbances can reduce coral cover enough that the reef is pushed past the threshold and makes it very difficult for the reef to recover to being coral dominant
-high grazing would be the only reason why a reef can survive multiple disturbances

104
Q

Alternate states model with Jamaica as an example

A

Initially was high coral cover and grazing
1. Hurricane Allen (1980): resulted in decrease in coral cover, didn’t cross over threshold, started to recover due to high grazing
2. Urchin disease (1983): wiped out a lot of urchins, loss of herbivory, pushed past threshold, system became algal dominant, still has highish coral cover
3. Hurricane Gilbert and White band disease on Acroporids (1988): significant decrease in coral cover

System remains at low grazing (no urchins) and low resilience
-could recover if there was a drastic increase in grazing

EEMB 147 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions