The term ‘algae’ represents a large range of photosynthetic organisms.
Seaweed is a type of algae, sometimes known as micro algae and generally live attached to rock or other hard organisms in coastal areas. It’s primary requirements are seawater and light (for photosynthesis). The presence of algae in an ecosystem is imperative as seaweed removes undesired nutrients from water and is a natural filter.
Algae farming: Growing cyanobacteria ( a group of bacteria that obtain their energy through photosynthesis) and algae does not require arable land. Researchers say that algae could be 10 or even 100 times more productive than traditional bio energy feedstocks. Furthermore, algae fuel is now known to be an alternative to liquid fossil fuel.
Algae is a bioindicator of water pollution as they change and adapt in relation to water chemistry, an intelligent reaction to problems that eco systems and humans face. Certain algae species’ flourish in polluted water. Many blue green algae occur in nutrient poor water, while some grow well in organically polluted waters..
Stigeoclonium tenueis- heavily polluted water
Nitzschia palea- mildly polluted
Cocconeis + Chamaesiphon- unpolluted
Navicula Accomoda- presence of sewage and organic pollution (this species occurs in the most heavily polluted water
How do we percieve algae?
The presence of algae is perhaps often seen as negative; dirty water that is unclean to enter and is unhealthy.
Slime moulds are catagorised in two distantly related families: “cellular” and “acellular”.
Cellular slime moulds spend the majority of their life cycles as individual, single celled amoebas. Once they have exhausted the resources of their immediate environment the individual cells join together to form a slug which travels to fresh pastures before fruiting and dispersing spores.
Acellular slime moulds have a “plasmodium” stage in their life cycles. Plasmodium is made up of millions of nuclei which share a single, gigantic cell without any membranes to separate them.
Much of the research around slime moulds is focused on the acellular variety (usually Physarum polycephalum), as it is a much more unusual life form, with many unexpected properties. For the remainder of this research, the term slime mould is used to refer to acellular slime moulds.
General
Although it lacks a brain or a central nervous system, polycephalum is capable of performing complex behaviours such as finding the shortest path through a maze, solving computationally difficult puzzles and making decisions based on multiple objectives.
polycephalum is part of the Protista kingdom, which contains a variety of unicellular eukaryotes (an organism with a complex cell or cells) that do not fit into the other kingdoms.
They are where the world of cellular biology collides with the macroscopic world.
How we perceive them
Due to their unusual biological properties and ease of culture, the acellular slime mould Physarum polycephalum is a favourite amongst cell biologists.
More recently, due to the way it constructs networks, it has become the become a model organism for a variety of disciplines including behavioural ecologists, town planners, computer scientists and artists.
How it grows, how it nurtures itself
Life cycle diagram
Plasmodia of acellular slime moulds form a fan-like sheet at the front, followed by a network of interconnected veins through which cytoplasm flows.
Because it forms a network with several fronts, polycephalum can feed from multiple food sources simultaneously.
Under nutritional stress and when exposed to light, vegetative growth stops and the slime mould fruits, releasing male and female sexual myxamoebas into the environment.
The myxamoebas feed and divide, and when a male and female amoebas meet they fuse to form a binucleate cell, which develops into a plasmodium.
In the natural environment slime moulds feed on bacterium, fungi and detritus.
In labs they are cultured on moist filter paper, agar or rolled oats.
Their optimal diet consists of 2 parts protein to 1 part carbohydrates.
Plasmodium are self-repairing, and can regenerate when part of it is cut away.
Slime moulds grown from different inoculations are repellant to each other, but can merge if the environmental factors force them to.
How it lives, how it interacts with its surroundings
When a vein contacts a food source, biochemical oscillators give rise to propagating waves, redirecting cytoplasm to that vein. The vein becomes thicker at the expense of those which do not form a direct link between the two parts of the organism. This combination of positive and negative feedbacks allows the organism to connect food sources via the shortest path.
Slime mould leave a thick mat of non-living, extracellular slime behind their path. It uses this as an external memory to avoid areas where it has been before. Using this, it is capable of solving the U-shaped trap problem, a test of autonomous navigational ability used in robotics.
The slime mould is capable of using a hierarchy of rules, for example: it will crawl across extracellular slime if they detect the presence of food.
There is evidence that slime moulds also have an intracellular memory which allows them to anticipate periodic events. A slime mould will rhythmically reduce their speed of movement if they become attuned to a light flashing on and off – even once the light remains permanently off.
Slime moulds are capable of making intelligent decisions. When offered a choice between food sources of differing quality (concentration of oatmeal), it is capable of choosing the source with the highest concentration.
Plasmodia trade off risk against food quality, a food needs to be 5 times higher in concentration before the slime mould will forage in the light.
Speed of decision making affects the accuracy of those choices. Then stimulated to make a fast decision between two food sources of differing concentration by the presence of light, it was less likely to make the correct choice.
Slime moulds also alter their search pattern depending on the quality of food sources they are already exploiting. When consuming a high quality food source the plasmodia will perform an area-restricted search. When feeding from a low quality source it will move away from the source before sweeping the area for alternative food sources.
Plasmodia can distribute their biomass proportionally across multiple food sources of differing nutrient quality to receive an optimal diet.
What affects its health in positive and negative ways
The distribution of a slime mould’s biomass across an environment displays the organism’s relative comfort level in each location. By observing this, researchers have been able to isolate which factors encourage and inhibit the growth of a slime mould.
Attractive substances such as oats increase flow of cytoplasm to a location, repellant substances such as salt reduce it.
Low light levels and high humidity increase flow, high light levels and low humidity reduce it.
How it eventually dies
When the resources in the slime mould’s environment become exhausted, or it becomes too large to maintain itself the plasmodia diverts all its energy away from growth and into producing spores.
The spores spread out, leaving the slime mould to decompose.
Additional properties
Cytoplasm veins are conductive and can carry voltages high enough to power an LED without killing the slime mould.
Nano particles can be picked up by the plasmodia and transported along it’s veins.
Magnetic nanoparticles (barium hexaferrite crystalline nanoparticles) are bio-compatable with the slime mould. Magnetic fields can be used to deflect the path of magnetized slime moulds in order to control their path.
Plasmodia have been found to have memristive properties.
Because separate colonies of slime moulds repel one another, multiple inoculations on nutrient rich agar spread out and form voronoi diagrams where their boundaries meet. Voronois are materially effiecient – potentially load bearing structures.
This semi-self-repelling nature also allows physical Boolean logic gates to be made.
Physarum is photo-sensitive, and experimental data suggests it can tell the difference between red and blue light.
When a plasmodia’s vein is heated up to 40oC its resistance increases 1000 times, making it a biological thermic switch. In about 10 minutes the slime mould reforms and continues unharmed.
To produce biodiesel efficiently an organism requires a high concentration of lipids in their bodies, which is true of slime moulds. Because they produce biomass at a rate that exceeds algae, they could be an alternative biological factory for the fuel.
Its applications in the world
polycephalum can be used to model network formation in a biological system.
Network performance involves a trade-off between cost, transport efficiency and robustness.
Inspired a mathematical model “The Physarum Solver” which is able to find the shortest path between many points in a real world network, such as the Tokyo subway.
The slime mould’s ability to anticipate periodic events hints at the cellular origins of primitive intelligence.
The slime mould’s networking behaviours have been used to explore and model creative thinking.
People migrate towards sources of safe life and higher income. Physarum migrates into environmentally comfortable areas and towards sources of nutrients. Plasmodium have been used to model pathways of migration from Mexico into the USA.
Slime moulds have been used as biological sensors, using their aversion to light to steer a small hexapod robot.
When I started this project I looked into various micro-organisms ranging from slide mould to forms of fungi. I found myself particularly interested in ‘Algae’. The first thing I did was type ‘Algae’ to Google and it gave me an array of definitions, wikipedia’s was the easiest for me to understand: a simple non- flowering, and typically aquatic plant part of a large assemblage that includes seaweeds and many single- celled forms. Algae is very popular, diverse and found all over the world, just from this initial research I wanted to explore more.
Algae is photosynthetic which means it releases oxygen because of this quality, the organism makes up a high percentage of the earths oxygen supply. This helps plants and marine life grow while also being many animals main food and oxygen source. Algae are single celled and float on water, they absorb food through their cell walls. They can multiply and that’s how they can cover large surface areas.
Algae is a very large and there are many different groups. subgroups and forms of this organism. The two largest sub groups were red algae and green algae. Green algae is most commonly land plants from marine and fresh waters. There are many various forms in this group such as Eugkenoza, Cecoza and Glaucopyta. Red Algae always inhabits marine environments and is multicellular.
This is a diagram which show’s the different groups of Algae
Morover, algae is not only common in sea and lakes but can even be found on animals (like turtles), it is essential to some underwater animals as it can provide shade to them when needed. Some forms of algae have high levels of unsaturated fatty acids, this is eaten by many types of fish. Fish oils contain omega three which is surrounded by algae, it is eaten by the animals and passed up the food chain
Having lots of types of algae is good and healthy for the eco system, the ocean being one of the largest. Algae absorbs nutrients, ammonia and phosphorus as too many of these can be bad for the overall health of water. From this I wanted to focus on something that heavily depends on algae to survive, I looked into coral due to the fact it is necessary to our oceans eco system and how coral reefs face many threats.
Diagram illustrating the effects of coral bleaching
Initially, I looked into the relationship that the algae and coral have. A healthy coral relies in the algae to survive, they depend on each other. Once the coral begins to get stressed to due ‘coral bleaching’ then the algae will leave the coral. The coral is then left bleached and vulnerable, without the algae it looses its food source, causing it to turn pal and more to susceptible diseases. The main causes of coral bleaching are:
Change in the ocean temperature– This is the number one cause for coral bleaching and it is due to climate change and the increased temperature.
Run off and pollution– storm generated precipitation can rapidly dilute ocean water and runoff can carry pollutants, these can bleach near shore corals.
Exposure to sunlight– when the temperatures are high, high solar irradiance contributes to bleaching in shallow water corals.
Extreme low tides– exposure to the air during extreme low tides can cause bleaching in shallow corals
In coral polyps there is a symbolic relation between the algae and the coral and this relation is called zooxanthellae. The coral provides the algae with a protected environment and the compounded needed for it to photosynthesise. This is described as a yellowish brown dinoflagellate in large numbers in the cytoplasm and many marine invertebrates, including coral polyps. This ‘zooexanthellene’ lives in the coral tissues and when coral becomes stressed the relationship is broken.
This image shows the ‘zooxanthellae’ in the coral
Finally, E.chromi, this is an idea of based of synthetic biology which theres a colour indicator added They engineered bacteria into produce a variety of coloured pigments, visible to the naked eye. This can help detect diseases and hopes in the future to help warn people about excess pollution in the sky. I could relate this idea to coral bleaching, if the coral is showing signs of being stressed it could change colour and this could somehow be communicated to marine life and not harm the eco system.
