Science Forums 2

[Michaelangelica]

I always thought algae were in the sea not in soil
Wrong!

Algae are primary producers, i.e. they are the start of the food chain. One third of all the carbon fixed on this planet is achieved by algae, largely in the oceans!

Soil Algae: Several hundred species of algae form three general groups - green , Blue-green algae and diatoms- have been isolated from soils, but a small number are prominent throughout the world.

They consist of eukaryotic cells: have a nuclei within a nuclear membrane. Algal populations typically range from 10,000 - 100,000 cells per gram of soil.

Green algae prefer moist, non flooded acidic soils while diatoms prefer well drained land rich in organic matter.
Blue-green algae, Cyanobacteria, are prokaryotes and are usually classified as bacteria Soil Algae contain chlorophyll enabling them like plants to carry out photosynthesis if exposed to light and moisture.

They produce substantial O.M in some fertile soils and certain algae excrete polysaccharides which increase soil aggregation.

FAO/AGL - Soil Biodiversity Portal

So this is where sweet soil comes from? (polysaccharides =complex sugars)

Algae are common in ponds and streams, but they are also common in soils.
They are pioneer species and contribute to building soil, making it possible for plant species to grow.
Algae photosynthesize energy from sunlight and contribute vast amounts of organic matter to the soil.
Many algae can also fix nitrogen and contribute this nutrient to the soil.
The organic matter that algae add to the soil improves soil quality because it is sticky and contributes to making soil porous.
. . .
Fungi and algae pair together to form lichens. The algae partner produces nutrients through photosynthesis and the fungus partner absorbs inorganic nutrients from the soil which the algae needs for growth.
Lichens can therefore colonize the harshest environments, even those with scarce nutrients, water, and cold temperatures.
Because lichens can absorb even trace inorganic and organic materials, they serve as an indicator of environmental quality, because they take up trace toxic materials in the environment.

The Environmental Literacy Council - Soil Creatures

ninety percent of carbon dioxide produced on Earth from natural processes comes from the biological activity of bacteria and fungi.

The Environmental Literacy Council - Soil Creatures

Garding you tail?

Soils are also home to a variety of snails, slugs, and insects, and, one of the most intriguing creatures of all, the tardigrade.
The tardigrade was first described in 1773 by a German naturalist Johann Goeze, who called it the "little water bear." The name tardigrade means "slow stepper" and describes the slow movement of these creatures. Tardigrades are considered to be related to insects but they are distinct enough to have their own phylum. Tardigrades are most unusual because of their color; although some are brown or colorless, they can also be pink, orange, green, or yellow. Tardigrades are predators in the soil, consuming protozoa, algae, fungi, nematodes, and other tardigrades. Tardigrades are also unusual because they can go into a state of suspended animation to survive when environmental conditions, such as temperature or moisture levels are unfavorable

The Environmental Literacy Council - Soil Creatures

These guys look like the tanks of the soil flroa and fauna

They look a bit bear-like!




Are they in Oz soil?

A PS on Algae- "Grass eats Cow"

There are algae species that can act both as “plants” and as “animals” at the same time.

As “plants” the algae produce their own food and as “animals” they can eat other plants or even their own grazers.
These organisms are called mixotrophs and their nutritional strategy is thus known as mixotrophy, in other words: “mixed nutrition”.
This dual nutritional behavior affects the notion of food chain mentioned above.
In a comparison, imagine if instead of a cow eating the grass, the grass grabs and eats the cow.

The thesis of Wanderson Carvalho had as one of the objectives to quantify in two mixotrophic species how much nitrogen and phosphorous are needed when they act as “plants” and as “animals”, respectively.
For example, under nutrient (nitrogen and phosphorus) deficient conditions, mixotrophs can outcompete other algae species by eating them or utilizing the little available nutrients dissolved in the water.
Wanderson also found out that “feeding as animals” can also provide carbon and energy to the mixotrophs if light is low or absent.

In absence of food, mixotrophs can use their photosynthetic capabilities to survive until suitable prey is available again.
Mixotrophs can decrease competition since they can feed on their competitors and predators alike. Mixotrophs can survive adverse periods and because of that many mixotrophs form blooms, becoming potentially harmful to the environment.

ScienceDaily: Understanding Algae That Are Both 'Plant' And 'Animal'