There is a branch of ecology, called synecology, which studies the relationships between ecosystems and communities of individuals. Within synecology, we find a part in charge of studies of the relationships between living beings, including feeding relationships, which are summarized in food chains, as is the case of the aquatic food chain.
Synecology explains that food chains are the way energy and matter move from one production level to another, also taking into account energy losses, such as respiration. In this article on our site we will explain what an aquatic food chain is, starting with the definition of food chain and food web.
Difference between food chains and webs
First of all, to understand the complexity of aquatic food chains we must know the differences between food or food chain and web and what each of them are.
A food chain shows how matter and energy move within an ecosystem through different organisms, in a linear fashion and unidirectional, always starting with an autotrophic being that is the primary producer of matter and energy, since it is capable of transforming inorganic matter into organic matter and non-assimilable energy sources into assimilable energy, such as the conversion of sunlight into ATP (adenosine triphosphate, energy source of living beings). The matter and energy created by the autotrophic beings will pass to the rest of the heterotrophic beings or consumers, which can be primary, secondary and tertiary consumers.
On the other hand, a food web is a set of food chains that are interconnected, showing a movement of energy and matter much more complex.
The aquatic food chain
The basic scheme of a food chain does not vary much between a terrestrial and an aquatic system, the most severe differences are found at the level of the species and the amount of accumulated biomass, being greater in ecosystems terrestrial. Below we will mention some species of the aquatic food chain:
Primary Producers
In the aquatic food chain we find that the primary producers are algae, whether unicellular or those belonging to the phyla Glaucophyta, Rhodophyta and Chlorophyta or, multicellular, those of the superphylum Heterokonta, are the algae that we can see with the naked eye on beaches, etc. In addition, we can find bacteria at this level of the chain, the cyanobacteria, which also carry out photosynthesis.
Primary consumers
Primary consumers in the aquatic food chain are often herbivorous animals that feed on microscopic or macroscopic algae and even bacteria. This level is usually made up of zooplankton and other herbivorous organisms
Secondary consumers
Secondary consumers stand out for being carnivorous animals, which feed on lower level herbivores. They can be fish, arthropods, waterfowl or mammals.
Tertiary consumers
Tertiary consumers are the supercarnivores. Those carnivorous animals that feed on other carnivores, those that form the link of secondary consumers.
Aquatic Food Chain Examples
There are different degrees of complexity in food chains. Here are x examples:
- The first example of an aquatic food chain is made up of two links. This is the case of phytoplankton and whales. Phytoplankton are the primary producer and whales are the only consumer.
- These same whales can form a chain of three links if they feed on zooplankton instead of phytoplankton. So the chain would look like this: phytoplankton > zooplankton > whale. The direction of the arrows indicates where energy and matter are moving.
- In an aquatic and terrestrial system, such as a river, we could find a chain of four links: phytoplankton > mollusks of the genus Lymnaea > barbels (fish, Barbus barbus) > gray heron (Ardea cinerea).
- An example of a chain of five links where we can see a supercarnivore is the following: Phytoplankton > krill > Emperor penguin (Aptenodytes forsteri) > Sea leopard (Hydrurga leptonyx) > Killer whale (Orcinus orca).
In a natural ecosystem relationships are not so simple Food chains are made to simplify trophic relationships and we can understand it better, but chains interact with each other in a complex network of food webs. One of the examples of food web could be the following, where we can see how a food chain is integrated:
