Answer:
Density is nearly 3 cabs per hectare
Explanation:
Given -
There are three three intertidal regions.
Area of each intertidal region is
hectares.
Number of crab in the intertidal regions are as follows -
Intertidal region I - 7
Intertidal region I - 2
Intertidal region I - 6
Sum of crabs in all three regions is equal to

Total area of all three intertidal regions is equal to
hectares
Now density per hectare is equal to total population of crab divided by total area of all the three intertidal regions
Density 
Density is nearly 3 cabs per hectare
1) 28 2) ovaries 3) fallopian tube 4) ovaries 5 & 6) ovary 7) ovulation 8 & 9) uterus 10) fallopian tube 11) sperm cell 12) uterus 13) fertilized 14) blood 15) uterine 16) vagina 17) 28 18) menstruation
Warmer oceans would mean less dissolved CO2 as well as other gases such as oxygen in the global ocean. Lower CO2 would result in a decrease in photosynthesis of autotrophs living in the oceans.