The second main family of sea grasses is the Zosteraceae family.

Around when Harland first proposed a global ice age, a climate model developed by Russian climatologist concluded that if a Snowball Earth really happened, the runaway positive feedbacks would ensure that the planet would never thaw and become a permanent block of ice. For the next generation, that climate model made a Snowball Earth scenario seem impossible. In 1992, a professor, , that coined the term Snowball Earth. Kirschvink sketched a scenario in which the supercontinent near the equator reflected sunlight, as compared to tropical oceans that absorb it. Once the global temperature decline due to reflected sunlight began to grow polar ice, the ice would reflect even more sunlight and Earth’s surface would become even cooler. This could produce a runaway effect in which the ice sheets grew into the tropics and buried the supercontinent in ice. Kirschvink also proposed that the situation could become unstable. As the sea ice crept toward the equator, it would kill off all photosynthetic life and a buried supercontinent would no longer engage in . Those were two key ways that carbon was removed from the atmosphere in the day's , especially before the rise of land plants. Volcanism would have been the main way that carbon dioxide was introduced to the atmosphere (animal respiration also releases carbon dioxide, but this was before the eon of animals), and with two key dynamics for removing it suppressed by the ice, carbon dioxide would have increased in the atmosphere. The resultant greenhouse effect would have eventually melted the ice and runaway effects would have quickly turned Earth from an icehouse into a greenhouse. Kirschvink proposed the idea that Earth could vacillate between states.

This family of sea grass is normally found in sub-tropic waters.

[A more detailed look at some emerging human-induced threats facing the seagrasses of the IRL is .]

Most of these sea grasses are found in tropical waters.

Durako, Michael J., Ronald C. Phillips and Roy R. Lewis III, eds. 1987. Proceedings of
the symposium on subtropical-tropical seagrasses of the southeastern United States. Fla.
Marine Res. Publ. No. 42, Fla. Dep. of Natural Resources, Bur. Marine Res., St.
Petersburg, FL. 209 pp.

New York: John Wiley & Sons, Inc., 1998."Sea Grass." Wikipedia.

The process of introducing carbon into the aquarium water through carbon dioxide fertilization does little to help in the growth of marine macro algae, but it would benefit a sea grass dominated system.

Seagrass beds are highly diverse and productive ..

In both systems the physical aspects of the tank design - particularly light and substrate requirements - are the most important. The approach that best fits an individual aquarist depends solely on the goals for the display in question. In lagoon style tanks the emphasis is on corals, and the seagrass is more or less a "highlighting" species. Since the biomass of plants is small, their nutrient demands tend to be low and are easily met by organic sources of nutrients within the tank (which we will cover shortly). There are already examples of systems such as this among Reef Central members (, , ). Seagrass dominated aquaria attempt to grow large stands of seagrasses and macroalgae and tend to have high nutrient demands that cannot always be met by organic sources alone. For some of these systems, inorganic sources of nutrients are dosed similar to what is already done in freshwater aquaria to maximize the plants' growth. Nutrient dosing in marine aquariums is admittedly atypical, and is covered briefly below as a preliminary guide for aquarists who are interested in marine planted tanks.

Seagrass meadows - Marine Biodiversity Wiki

Most species of sea grasses can absorb large amounts of carbon from the both their roots and leaves, while macro algae are thought to need varying amounts depending on the species.

Ecological selection pressures for C 4 photosynthesis in the grasses

Eiseman, N. J. 1980. An illustrated guide to the seagrasses of the Indian River region of
Florida. Tech. Rep. No. 31, Harbor Branch Found., Inc., Fort Pierce, FL.

Seagrass types in the Gulf of Mexico - SUP Englewood

In addition to the small epiphytic algae, larger algae also compete with seagrasses, and introduced invasive seaweed species can displace native seagrass species. One important example is the invasion of , a seaweed nicknamed "the killer algae." Released into the , by 2000 it covered more than 131 square kilometers (50 square miles) of the Mediterranean coastline, overgrowing and replacing the native Neptune seagrass () and reducing the ecosystem's biodiversity. Since then, invasive Caulerpa has been found in California and southwestern Australia where eradication programs are in place to prevent its spread.