OA OCEAN ACIDIFICATION & MULTIPLE STRESSORS

Question 1

what did the different graphs of growth rate over 8 days exposure vs 6 months exposure to high CO2 conditions in the cold water coral Lophelia pertusa show? what wasn’t there a change in though? what does this mean?

Answer 1

• one showed decreasing growth and the other showed increasing growth over a longer time period to same CO2 treatment
• could mean acclimation to the high CO2 conditions
• over long term, animals able to acclimatise to the conditions resulting in increased calcification
• didn’t see a change in metabolic rate though; study didn’t measure any other physiological processes
• so increase in growth rate could’ve come at the expense of other processes

Question 2

what other drivers of change are affecting marine organisms and ecosystems?

Answer 2

• temperature
• overfishing/disturbance in general
• salinity
• pollution
• invasive species
• habitat loss

Question 3

what were the impacts of warming on the keystone species Pisaster ochranceus?

Answer 3

• feeding and growth rates increased under warming and high CO2
• calcification suppressed slightly

Question 4

what were the differences in growth rate responses between the invasive Elminius modestus and the native Semibalanus balanoides to high temperature and CO2? what did this experiment show strong impacts from in S. balanoides populations, due to calcium content and survival data? what does this suggest for the effect of pH on barnacle larvae in their first month or so of settlement?

Answer 4

• the native species didnt show any clear effects in growth rate betw high temps and CO2 levels
• the invasive species showed significantly lower growth rates at high CO2 and temp
• S. balanoides populations will be strongly impacted by combined effects of OA and rising temperatures
• a slight decrease in pH alone isn’t sufficient to directly impact the barnacle larvae, but in conjunction with 4-5°C rise in temp, there will be signif change in the organisms’ biology, especially for the native S. balanoides.

Question 5

what were the long-term effects of warming and OA in alitta (nereis) virens, the king ragworm, on their bioturbation behaviour? why is this important for this species?

Answer 5

• seasonal cycle in bioturbation breaks down under warming scenario; species respond to seasonal variation
• OA alone has relatively little impact on behaviour
• they affect nutrient cycling within sediment; important because they’re vital for bringing oxygen into the sediment, thus affecting food web as a whole

Question 6

what were the combined impacts of OA and hypoxia on the fish Menidia menidia?

Answer 6

• greater sensitivity of early life estuarine fish to low oxygen compared to low pH conditions
• reduced fitness of this species may impact higher trophic organisms
• took them much longer to hatch, with reduced hatching success and post-larval survival especially under low oxygen conditions
• early life stages of fish are much more sensitive to lower oxygen conditions than they are to pH

Question 7

SUMMARY:
- ocean acidification is occurring at the same time as a multitude of other stressors including w…, e…, h… d… etc.
- all of these global changes interact to affects marine o… and e…
- responses could be s…, n… or ant… depending on the s… or the physiological p… involved
- the effects of additional stressors (w…, h…) may outweigh effects of ocean acidification and depend on seasonal t…
- organism s… to future climate conditions, will depend on their e… history, species-specific p…, and int… between their biotic and a… environment.

Answer 7

warming
eutrophication
habitat destruction
organisms
ecosystems
synergistic, neutral or antagonistic
species
processes
warming
hypoxia
timing
sensitivity
environmental
physiology
interactions
biotic