- Aquatic organisms are interconnected living entities that thrive in aquatic environments, encompassing oceans, rivers, and various water bodies.
- These organisms spend their entire life cycles in water, employing specialized organs to extract oxygen from their aquatic surroundings.
- Oxygen uptake methods vary, with some absorbing it through their skin and others through gills.
- Aquatic organisms are broadly categorized into Neuston, Periphyton, Plankton, Nekton, and Benthos based on their habitats and ecological roles.
CATEGORIES OF AQUATIC ORGANISMS
Aquatic organisms are classified based on their habitats and their ability to move within them. The species, both flora and fauna, in aquatic ecosystems are diverse but can be grouped into five categories according to their life forms or locations.
NEUSTON
- Neuston, also known as pleuston, refers to organisms living on the surface of oceans, estuaries, lakes, rivers, or ponds.
- Coined by Naumann in 1917, the term encompasses organisms residing on both the upper and lower sides of the water’s surface.
- Neuston can be found in the surface microlayer between the top and bottom sides of the water surface.
- These organisms play a crucial role as a food source for zooplankton and are accessible to seabirds flying above oceans.
- Example: Water Strider, a common freshwater neuston.
PERIPHYTON
- Periphyton constitutes a complex mixture of algae, cyanobacteria, heterotrophic microorganisms, and detritus attached to submerged surfaces in aquatic ecosystems.
- This community has adapted to live on hard surfaces and aids in the removal of solids and dissolved contaminants in aquaculture food production systems.
- The temperature range required for periphyton growth is linked to the environmental temperature stability.
- Example: The cyanobacterium Mastigocladium laminosces is a prevalent taxon in periphyton due to its resilience to freezing and desiccation.
Plankton
- Plankton refers to a diverse group of organisms unable to swim against water currents or wind.
- Comprising individual creatures known as plankters, plankton varies widely in size, ranging from microscopic bacteria to large species like jellyfish.
- The distribution of plankton depends on factors such as light availability and nutrient levels.
- Plankton serves as a crucial food source for larger aquatic species.
NEKTON
- Nekton comprises living organisms capable of swimming and moving independently of currents.
- Coined by German biologist Ernst Haeckel, the term distinguishes active swimmers from passive plankton carried by currents.
- Nekton can be found in both the photic and aphotic zones of water bodies.
- They play a vital role in marine food webs, linking primary consumers to higher trophic levels.
BENTHOS
- Benthos refers to organisms living on, in, or near the bottom of seas, rivers, lakes, or streams.
- The benthic zone, including the sediment surface and sub-surface layers, constitutes the ecological region at the lowest level of water bodies.
- Macrobenthos, organisms larger than 1 mm, is extensively studied in benthic research.
- Benthic creatures can be categorized based on whether they live on the ocean floor or a few centimeters below it.
FACTORS AFFECTING THE PRODUCTIVITY
Sunlight:
- Sunlight penetration in the water column decreases rapidly, influencing the depth of plant dispersal in lakes.
- The photic zone, the sunlit upper layer, allows light penetration, but photosynthetic activity is restricted based on water transparency.
- The aphotic zone, located below the littoral and photic zones, lacks sufficient light for photosynthesis, and oxygen consumption occurs throughout its depth.
- Different zones are categorized based on light penetration and plant distribution.
Dissolved Oxygen:
- Oxygen concentration in aquatic ecosystems is dynamic, influenced by factors affecting input and output.
- Dissolved oxygen, vital for aquatic life, enters through air-water contact and photosynthetic activity of aquatic plants.
- Temperature affects oxygen solubility, with warmer water holding less dissolved oxygen.
- Oxygen leaves the water through organism respiration, and levels below 3-5 ppm can be lethal for many aquatic organisms.
Transparency:
- Transparency, or water clarity, is a crucial factor influencing aquatic productivity.
- Suspended particulate matter, including clay, silt, and phytoplankton, can make water turbid, limiting light penetration.
- Turbidity impedes photosynthetic activity, impacting the growth of aquatic plants and organisms.
Temperature:
- Water temperature, which changes more slowly than air temperature due to water’s higher specific heat, plays a vital role in aquatic ecosystems.
- Aquatic creatures have narrow temperature tolerance limits, making them highly sensitive to even minor temperature changes.
- Temperature fluctuations affect the metabolic rates of organisms, influencing their growth, reproduction, and overall survival.
- These limiting factors apply to diverse aquatic ecosystems such as lakes, ponds, rivers, streams, estuaries, oceans, and seas.
- Understanding these factors is crucial for assessing and managing the health of aquatic habitats and the organisms that inhabit them.
FAQs – Aquatic Organisms and Factors Affecting Aquatic Habitats
1. What are aquatic organisms, and where do they live?
A: Aquatic organisms are living entities thriving in aquatic environments, including oceans, rivers, and various water bodies. They spend their entire life cycles in water, using specialized organs for oxygen extraction.
2. How are aquatic organisms categorized?
A: Aquatic organisms are categorized into Neuston, Periphyton, Plankton, Nekton, and Benthos based on their habitats and ecological roles.
3. What is Neuston, and where can it be found?
A: Neuston, also known as pleuston, refers to organisms living on the surface of oceans, lakes, rivers, or ponds. They can be found on both the upper and lower sides of the water’s surface, playing a vital role in the ecosystem.
4. What is Periphyton, and what role does it play in aquatic ecosystems?
A: Periphyton is a mixture of algae, cyanobacteria, microorganisms, and detritus attached to submerged surfaces. It aids in removing contaminants and contributes to the overall health of aquaculture food production systems.
5. What is Plankton, and why is it essential?
A: Plankton comprises organisms unable to swim against currents. Ranging from microscopic bacteria to large species like jellyfish, plankton serves as a crucial food source for larger aquatic species.
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