1. Remember that ecosystems (sometimes I use the term habitats instead) with abundant nutrients and sunlight will have high primary productivity, high biomass, vigorous food chains.
Ecosystems with scarce nutrients will tend to have low primary productivity and low biomass.
An exception to this is a coral reef ecosystem. Although the amount of incoming nutrients might be low, the system is overall so efficient that coral reefs have high primary productivity, high biomass, and high diversity.
Ecosystems with constant physical conditions will have high diversity. Physical conditions include things like salinity, water temperature, and oxygen content. By high diversity we mean that the number of species is great even though the number of individuals representing those species might be small.
Ecosystems with highly variable physical conditions will have low diversity.
The following is a summary page for the ecosystems (habitats) described in the text:

2. Coastal Habitats (highly variable physical conditions)
Estuaries
Salt marshes low diversity, high productivity
Mangrove swamps
Coral Reefs high diversity, high productivity
Continental Shelves
Neritic zone high diversity, high productivity
(water column above shelf)
Sublittoral zone high diversity, high productivity
(floor of cont. shelf) energy levels critical
Open Ocean Habitats (scarce nutrients)
Photic zone high diversity, low biomass, low productivity
( 100 meters deep)
Dysphotic zone high diversity, low biomass, low productivity
( meters depth)
Aphotic zone high diversity, low biomass, low productivity
(starts meters down)
Deep sea bottom high diversity, low biomass, low productivity
lack of competitive expulsion