I havent been there, though i'm doing my field study at the moment so i could give you a few tips i guess lol
The relationship of organisms could include things such as
mutualism, allelopathy, parasitism, commensalism and predator/prey.
Mutualism is is a relationship where both organisms involved benefit, and example a bee and flower. the bee gets the pollen it needs and the flower gets a chance to germinate as of this.
Allelopathy is a plant relationship where one plant benefits or harms another. An example could be fern fronds which produce a chemical to preven the germination of pine seeds. This allows the fern to have less competition for needed materials.
Parasitism is pretty easy, its simply where one organism benefits off of that of another. A common example being a flea living on a dog.
Commensalism is a relationship where neither organism involved is harmed or disadvantaged, but one may be slightly advantaged. A good example is a bird living in a tree. The bird gets a raised place to live and the tree isnt disadvantaged in the process.
predator/prey is like the food chain sort of. Its like what eats what lol.
First of all you have your producers, which are mearly things like grasses and weeds. Then there is the first consumers which are tings that only eat the producers, these are generally herbivores, such as a very small fish. after the first consumer there is the second consumer which is a 'first order carnivore' and so on.
This should generally cover the
organism relationships part of your assignment.
Just find examples of the above from the area you visited.
As for the abiotic factors i cant really help. Im yet to do that lol.
You could go back to the area with a datalogger, or even just a pool ph kit and test the ph of soils and any present water and then graph it an explain it in the report. Other factors could include
light intensity, salinity, temperature, ect.
hope i helped, best of luck with the assignment.