Polar:

Question 1

What are five abiotic and biotic factors that influence polar marine invertebrates?

Answer 1

1. Low, stable temperatures - stenothermal species that can only tolerate a small range of temperatures
2. Presence of sea ice and ice scouring
3. Highly seasonal productvity - many of the year has no light
4. High oxygen concentrations - don’t need complex respiratoty or circulatory systems
5. High CO2 concentations and calcium carbonate solubility

Question 2

What infleunce do these five features have on the biology of marine invertebrates?

Answer 2

• Low, stable temperatures: this has led to stenothermal species evolving to only be able to tolerate a narrow temperature range. It has resulted in slow metabolic rates, growth and development in many Antarctic marine invertebrates
  
  • Presence of sea ice and ice scouring: this effects the zonation of benthic communities. For example, the bare zone (0-15 m) is largely devoid of sessile animals due to ice scouring and anchor ice. This had forced many species to adapt to deeper waters or develop strategies to cope with periodic disturbances
  • Highly seasonal productivity: the Antarctic experiences extreme seasonality in light and primary production, where most of the year there is none of this. This has forced invertebrate species to develop well-develop suspension feeding and generalist feeding behaviours such as omnivory, necrophagy, and coprophgy
  • High oxygen concentration: there is more dissolved oxygen in these waters which has allowed animals without complex respiratory or circulatory systems to evolve and survive in these conditions, as well as contributed to gigantism in certain groups, as there is less oxygen limitation on body size
  • High CO2 concentrations and calcium carbonate solubility: this results in reduced calcification rates among marine invertebrates