Aquatic Organisms

Aquatic Organisms are living organisms that are close-knit and reliant on one another in the aquatic environment. They live in the oceans, rivers, and other bodies of water. Aquatic organisms live their entire lives in the water. They use particular organs to take oxygen from the water. Some ingest it through their skin, while others ingest it through their gills. Neuston, Periphyton, Plankton, Nekton, and Benthos are the categories of aquatic organisms.

Aquatic Organisms – Categories

Aquatic Organisms are classified on the basis of their zone of occurrence and their ability to cross these zones. The organisms (both flora and fauna) in the aquatic ecosystem are unevenly distributed but can be classified on the basis of their life form or location into five groups. They are as follows:

Neuston

Neuston, also known as pleuston, are creatures that chill on the surface of oceans, lakes, rivers, or ponds.
The word “neuston” was made up by a person named Naumann in 1917 to describe critters living on the surface of freshwater ecosystems.
These organisms can either live right on top of the water or underneath it.
They can also be found in the thin surface layer that forms between the top and bottom sides of the water.
Neuston serves as a food source for zooplankton making the journey from deeper layers to the surface.
They’re like the buffet for seabirds flying above the oceans.

Periphyton

In many water environments, periphyton is a diverse mix of algae, cyanobacteria, tiny organisms that eat organic matter, and debris that cling to submerged surfaces.
Periphyton has adapted to live on hard surfaces, like rocks or submerged structures.
The temperature conditions suitable for periphyton growth are closely tied to the overall temperature range and stability in its surroundings.
Periphyton communities play a crucial role in aquaculture food production systems by helping to remove both solid particles and dissolved contaminants.
Among periphyton organisms, the cyanobacterium Mastigocladium laminosces stands out as the most common.
This is largely because it can endure freezing temperatures and drying out, showcasing its resilience in various environmental conditions.

Plankton

Plankton is a diverse group of organisms that live in water (or air) and are unable to swim against the stream (or wind).
Plankters are the individual creatures that make up plankton.
Planktons range in size from 0.2 meters to more than 20 meters.
Their distribution varies depending on the availability of light and nutrients, from microscopic bacteria to giant species like jellyfish.
Planktons are a source of food for large aquatic species.

Nekton

Nekton refers to living things that are skilled swimmers and can navigate through water without being pushed around by currents. Think of them as the go-getters in the aquatic world.
The term “nekton” was coined by German biologist Ernst Haeckel. He came up with it to draw a line between creatures that actively swim in water and those who just go with the flow, like plankton that drift along with the current.
Nektons can be found in both well-lit areas (photic zones) and darker, deeper regions (aphotic zones) of the water. They’re versatile swimmers, exploring different parts of the aquatic world.
In the grand scheme of things in the ocean, nektons play a crucial role. They act as the middlemen, connecting the plant-eating crowd (primary consumers) with the big players higher up in the food chain. So, they’re basically the traffic directors of the underwater world.

Benthos

The community of living organisms found at the bottom of oceans, rivers, lakes, or streams is called benthos. These organisms reside in, on, or near the sediment surface in the aquatic environment.
The benthic zone, referring to the lowest level of water bodies like oceans, lakes, or streams, encompasses the sediment surface along with some layers beneath it. This ecological region is crucial for understanding the dynamics of aquatic ecosystems.
Among the benthic organisms, macrobenthos, which are larger than 1 mm in size, have received the most attention in scientific studies. Researchers have extensively explored this group to gain insights into the underwater life and its impact on the broader ecosystem.
Benthic creatures can be classified into two main categories based on their proximity to the ocean floor. Some reside directly on the ocean floor, while others are found just a few centimeters below the surface. This distinction helps in understanding the diverse habitats and adaptations within the benthic environment.

Factors Limiting the Productivity of Aquatic Habitats

Sunlight and Plant Dispersal:

In the water, sunlight quickly diminishes, affecting plant distribution.
The depth to which light penetrates a lake determines how far plants can spread.

Photic Zone:

This is the upper layer of aquatic ecosystems where light enters, but plant activity is limited.
Transparency of the water defines the depth of this zone.
Photosynthesis and respiration happen simultaneously.
It extends from the lake’s surface to a depth where light is only 1% of the surface level.

Aphotic Zone:

This is the dark area below the photic zone where light and plant growth are restricted.
It’s situated beneath the littoral and photic zones, where light is too low for photosynthesis.
The profundal zone is the unlit part of the aphotic zone.
Oxygen is consumed here due to respiration at all depths.

Dissolved Oxygen:

Oxygen concentration in water varies based on factors influencing input and output.
In freshwater, dissolved oxygen is 0.0010 percent by weight, much lower than in the air.
Oxygen enters through air-water contact and plant photosynthesis.
Dissolved oxygen leaves via organism respiration.
Temperature affects oxygen solubility; warmer water is less soluble.

Temperature’s Impact:

Water temperature changes more slowly than air temperature.
Water’s higher specific heat makes it less susceptible to temperature changes.
Aquatic organisms are more affected by water temperature changes than air temperature changes.
Raising water temperature accelerates oxygen depletion, impacting aquatic life.

Transparency and Aquatic Productivity:

Transparency, affected by suspended particles, influences light penetration.
Turbid water limits photosynthesis due to reduced light penetration.

Temperature and Aquatic Ecosystems:

Aquatic ecosystems, including lakes, rivers, and oceans, are defined by their inhabitants and limiting factors discussed above.

Conclusion

Every aquatic creature, from a tiny bacterium to a majestic blue whale, has its own unique identity. It’s not just their size, but the genetic makeup of plants and animals that sets them apart. These underwater beings play a crucial role in our survival. We depend on a variety of aquatic plants and animals, not just for their existence but for the valuable roles they play in their ecosystems. Imagine how much tougher life would be without them – fewer medications, fewer job opportunities, and a less robust economy. The incredible diversity of aquatic life truly enriches our human experience.

Read Also: Aquatic Ecosystem