Carl Reefs 4

Question 1

why don’t corals grow in water deeper than ~50-70m?

Answer 1

most coral grown in depths of 25m or less because they need sufficient light for photosynthesis. They are associated with usually clear, unproductive waters

Question 2

what are the three most common forms of shading for coral reefs?

Answer 2

• Increased turbidity in association with changes in land-use practices and its affects freshwater discharge
• Eutrophication of coastal waters
• changes in the population numbers of natural grazers which keep the reefs clean of external algae build-ups

Question 3

“The richness of both _______ and __________ decreased with increasing turbidity and chlorophyll.

Answer 3

hard corals and phototrophic octocorals

Question 4

maximum mean annual concentration of chlorophyll and minimum annual secchi depth

Answer 4

[Chlorophyl]= 0.45um
secchi= 10m

Question 5

how far did the Burdekin River discharge plume extend to in the 2010-2011 wet season?

Answer 5

> 50km offshore and >100km northward

Question 6

what kind of deposition of sedimentation poses a greater threat to corals? why?

Answer 6

organic, greater than mineral.

-corals find it more difficult to remove STICKY, MUDDY MARINE SNOW than discrete mineral particles

Question 7

how has the increase in sugarcane farming in australia affected the corals reefs?

Answer 7

had led to both the increased turbitity and increased nutrient concentrations of freshwater discharge

Question 8

what environmental effect are COTS linked to?

Answer 8

Increased eutrophication

Question 9

COTS along with what other factor are the leading causes of coral cover losses of the past 27 years?

Answer 9

tropical cyclones

Question 10

COTS has attibuted what percent of damage to the coral reefs?

Answer 10

42%

Question 11

name 6 main threats to corals

Answer 11

• cyclones
• COTS
• bleaching
• run-off
• pollution
• coral (growth r`ates)

Question 12

How do future plans need to change in comparison with the historical efforts of conservation efforts directed toward reserve implementations

Answer 12

new approaches are needed to sustain ecosystem function in exploited areas

Question 13

how can macroalgae negatively impact coral?

Answer 13

• interferes with coral recruitment
• surpresses coral growth and fecundity
• can cause direct albeit localised coral mortality to certain species.
• recovery rate of coral poplns is disminished by macroalgal blooms and forms feedbacks taht drive reef decline further

Question 14

what determines positive or negative feedback, driving a reef toward either unhealthy or healthy systems?

Answer 14

depends on grazing intensity is high enough to prevent the start of an algal bloom

Question 15

what is a major grazer of patch reefs in the caribbean?

Answer 15

the urchin Diadema antillarum

Question 16

is there one specific species of herbivous fish that is important to coral reefs?
name some

Answer 16

no, the best is a diverse amount of different herbivorous fish.

• redband parrotfish
• princess parrotfish
• ocean surgeonfish

Question 17

the shift from coral to algal dominance of most carribean reefs ince the mid 1990s has been initiated by what?

Answer 17

a combination of

• the mass die-off of sea urchings
• overfishing of parrotfish

Question 18

what is the main determining factor for the health of caribbean coral reefs?

Answer 18

overfishing, not climate change or pollution

Question 19

what are some of the conventional fisheries management tools and strategies put in place to protect carribbean coral reefs?

Answer 19

• area closures
• gear restrictions
• species ban
• temporal closures
• active restoration

Question 20

what are some identified characteristic thresholds which can identify coral reef regime shifts?

Answer 20

• structural complexity
• water depth
• fish density
• -> to predict reef responses to an extreme weather event

Question 21

regime shifts from corals to macroalgae occur mostly due to what event?

Answer 21

coral bleaching

Question 22

recovery from regime shift was favored when?

Answer 22

when reefs were structurally complex and in deeper water

• when density of juvenile corals and herbivorous fishes was relatively high
• when nutrient loads were relatively low