Ecology Fundamentals: Aquatic, Terrestrial, Marine, and Freshwater Environments

Ecology: Understanding Earth's Biosphere

Ecology is the scientific study of the behavior of the biosphere, utilizing various methods to understand the interactions between organisms and their environment.

Studying Aquatic Environments

Key Parameters in Aquatic Environments

• Light Penetration

  Light intensity softens as it enters water. It is typically measured using a Secchi disc to determine water clarity and light penetration depth.

• Water Temperature

  Temperature generally decreases with depth in aquatic environments. Specialized thermometers are used to measure these variations.

• Salinity Levels

  Salinity, the concentration of dissolved salts, is relatively constant within a given mass of saltwater. It is measured using instruments like refractometers or conductivity meters.

• Dissolved Oxygen

  The amount of dissolved oxygen in water varies significantly, often depending on proximity to the surface, temperature, and biological activity. It is measured through chemical analysis of water samples.

• Species Diversity

  The diversity of species within an aquatic ecosystem can be determined by in situ observation, identification, and enumeration of different species present.

• Species Abundance Survey

  The abundance of a particular species is typically surveyed using various estimation methods, including direct counts or sampling techniques.

• Mark-Recapture Method

  This method is used to estimate total population size. The formula is: Total Population = (Number in First Sample × Number in Second Sample) / Number Marked in Second Sample.

Studying Terrestrial Environments

Key Parameters in Terrestrial Environments

• Temperature Measurement

  Temperature in terrestrial environments is measured with thermometers; the most commonly used types record both maximum and minimum values over a period.

• Precipitation Measurement

  Precipitation is measured with a rain gauge, a container with a graduated scale that collects rainfall over a specific time period.

• Plot Sampling (Quadrat Method)

  Plot sampling, also known as the quadrat method, is a technique that involves defining a specific area of ground (a plot or quadrat) to systematically list and quantify all species found within it.

Marine Ecosystems: Zones and Characteristics

Marine Zones

• Neritic Zone

  The neritic zone corresponds to the waters located above the continental shelf. This zone is highly dependent on light and is situated between the coast and the continental slope. Light typically penetrates to about 100 meters in this area, supporting rich biodiversity.

• Pelagic Zone

  The pelagic zone encompasses the open ocean waters beyond the continental shelf, extending into the deep sea.

Pelagic Layers

• Epipelagic Layer

  This layer corresponds to the superficial waters of the pelagic zone. It is characterized by abundant sunlight and a large amount of plankton, forming the base of the marine food web.

• Bathyal Layer

  The bathyal layer extends from the epipelagic stratum down to approximately 4000 meters depth. Fauna found here includes various mollusks and echinoderms, adapted to lower light and colder temperatures.

• Abyssal Layer

  The abyssal layer is found below 4000 meters depth. This deep-sea environment is characterized by extreme pressure, perpetual darkness, and very cold temperatures, inhabited by highly specialized animals adapted to these unique conditions.

Freshwater Ecosystems: River Course Dynamics

River Course Sections

• Upper Reaches (Headwaters)

  In the upper reaches, the water is typically poor in organic matter and flows with great speed due to the high slope. The riverbed is usually narrow, shallow, and characterized by a stony bottom.

• Middle Course

  In the middle course, the water begins to accumulate organic matter, and its velocity decreases as the slope lessens. The riverbed expands, and mud and sand accumulate at the bottom.

• Lower Reaches (River Mouth/Estuary)

  In the lower reaches, the water is rich in organic matter and circulates at a low rate due to the minimal slope. The riverbed is wider and often mixes with seawater in estuarine environments, creating unique brackish habitats.

Terrestrial Ecosystems: Latitudes and Biomes

Climatic Latitudes

• Tropical Latitudes

  In latitudes near the Equator, temperatures are consistently warm throughout the year because the sun's rays arrive perpendicularly, providing intense solar radiation.

• Middle Latitudes

  In these areas, temperatures exhibit significant seasonal variation, being warmer in summer and colder in winter due to the changing angle of the sun's rays.

• Polar Latitudes

  Located near the Earth's poles, these regions experience the coldest temperatures because the sun's rays arrive obliquely, resulting in less concentrated solar energy.

Biomes

A biome is a large ecological region characterized by distinct terrestrial characteristics, including climate, vegetation, and wildlife, occupying a very wide geographical area.