Aquatic Ecosystems: A Deep Dive
Symbiotic Relationships
Mutually beneficial relationships between two agencies often lead to total dependence between the two species. A common example is the relationship between a heterotrophic organism (like a human) and an autotrophic alga (which produces organic matter).
Aquatic Study Methods
Biotropica
Several measurements are essential for aquatic studies. At different depths, specialized tools like the Van Dorn or Niskin bottle are used for water sampling. Avoid mixing these samples with other containers.
Other Factors to Measure
Light
Sunlight is the primary energy source for autotrophic organisms. Light intensity decreases rapidly with water depth, limiting the distribution of these organisms.
Temperature
Water temperature also decreases with depth as solar radiation is absorbed by the upper water layers.
Salinity
Salinity is the amount of dissolved salts in a given volume of water, measured using salinometers.
Dissolved Oxygen
Dissolved oxygen is crucial for the respiration of aquatic organisms.
Biocinesis
Biocinesis is the study of an aquatic ecosystem to determine the abundance of each species and the overall species diversity. Species abundance refers to the number of individuals of a particular species within the ecosystem.
Biotope
The biotope study focuses on environmental factors affecting vegetation.
Key Factors
Temperature
Temperature is measured using thermometers.
Precipitation
Precipitation is measured using a rain gauge, which collects rainfall or snow. Measurements are typically recorded in millimeters.
Life in the Aquatic Environment
The aquatic environment, composed of water, covers a significant portion of the Earth’s surface. Organisms in this environment have evolved specific adaptations.
Water Surrounding Organisms
Aquatic organisms do not need protection from desiccation. Worms, for example, thrive in aquatic environments due to the constant moisture.
Low-Temperature Oscillations
Water absorbs heat from the sun more effectively than air or land, resulting in smaller temperature fluctuations and a more stable environment for aquatic life. Most aquatic vertebrates, excluding cetaceans, are poikilothermic.
Water Density
The higher density of water compared to air allows many aquatic organisms to maintain buoyancy without rigid body parts.
Marine Ecosystems
Oceans and seas hold 97% of the Earth’s water and cover 70% of the planet’s surface, with a salinity of approximately 35%.
Neritic Zone
Biotope
This slightly sloped area between the coast and the continental slope allows light penetration up to about 100 meters deep.
Biocenosis
Organisms in this zone are often attached to rocks or the seabed. Algae like laminaria and cormophytes (plants with stems, roots, and leaves) like posidonia are common. Mussels, fish, and various bird species also thrive here.
Pelagic Zone
Biotope
The sunlit surface layer of the open ocean, where light can penetrate up to 200 meters.
Biocenosis
This zone is characterized by macroscopic plankton, including photosynthetic microorganisms like algae and bacteria. Fish and marine mammals like dolphins and orcas are also abundant.
Bathyal Zone
Biotope
This dark zone extends from the limit of sufficient light for photosynthesis (around 200m) down to 4,000 meters. The abyssal zone extends beyond 4,000 meters.
Biocenosis
Life in the bathyal zone is adapted to the absence of light. Photosynthetic organisms are absent. Fish and other consumers, like shellfish, dominate. In the abyssal zone, decomposers feed on organic matter sinking from upper layers. Deep-sea fish often have large mouths and sharp teeth for capturing prey.