Aquatic Ecosystems and Biodiversity

Aquarium Characteristics

• A functioning aquarium exhibits a community, a habitat, and an ecosystem, but not a niche. A niche describes an organism's specific role within a habitat.

Community Definition

• A community is a group of different species living together in a specific area.

Habitat Analogy

• Habitat relates to physical location, like a niche relates to function.

Biodiversity Measurement

• Biodiversity cannot be reasonably measured for a single population. Ecosystems, habitats, and communities are appropriate contexts.

Succession Definition

• Succession is the replacement of one community by another. It occurs as a consequence of existing community change, not as an immediate response to a new food web or a glacial retreat.

Trophic Levels for Herbivores

• Herbivores, animals that feed on plants, are at least in the second trophic level.

Decomposers

• Examples of decomposers include worms and fungi/bacteria.

Population Properties

• Size: Population size is the total number of individuals in a population, limited by birth rate, death rate, immigration, and emigration.
• Density: Population density is the number of individuals per unit area or volume, often estimated through sampling techniques.
• Dispersion: Three patterns of dispersion exist:
  • Clumped: The most common pattern, where individuals cluster for safety or resources.
  • Uniform: Individuals are evenly spaced, often due to competition or secretion of toxins.
  • Random: Spacing occurs without any special attraction or repulsion.

Population Growth Models

• Exponential growth represents theoretical, continuous growth without limits.
• Limited (logistic) growth reflects actual growth, affected by limiting factors.

Life History Strategies

• r-strategists: Opportunistic organisms with rapid reproduction, many small offspring, rapid maturation, and single reproductive episodes (e.g., insects).
• K-strategists: Organisms with slow reproduction, few large offspring, slow maturation, and multiple reproductive episodes (e.g., mammals).

Trophic Interactions

• Scavengers: Feed on dead bodies (e.g., falcons, fungi).
• Saprophytes/Decomposers: Break down dead organisms into useful forms for the soil (e.g., fungi, bacteria).
• Intraspecific competition: Competition between members of the same species.
• Interspecific competition: Competition between members of different species.

Animal Activity Cycles

• Diurnal animals: Active during the day (e.g., birds).
• Nocturnal animals: Active at night (e.g., owls, cockroaches).

Planktonic Organisms

• Phytoplankton: Autotrophs (producers) like diatoms.
• Zooplankton: Heterotrophs (consumers) like copepods.

Trophic Levels

• Autotrophs: Producers that make their own food through photosynthesis (e.g., plants, algae, phytoplankton).
• Heterotrophs: Consumers unable to produce their own food (e.g., fungi, animals, decomposers, zooplankton).

Biological Magnification

• Higher trophic levels accumulate higher concentrations of toxins. Carcinogenic and teratogenic toxins accumulate in fatty tissues.

Food Relationships

• Predation: One organism kills another (e.g., snake and frog).
• Commensalism: One benefits, the other is unaffected (e.g., remora fish and shark).
• Mutualism: Both benefit (e.g., tick bird and rhinoceros, lichen).
• Parasitism: One benefits, the other is harmed (e.g., tapeworm and human).
• Symbiosis: Includes all food relationships. Co-evolution results from species interactions.

Food Webs

• Food webs are more complex and accurate than food chains because they include multiple food chains and interactions between various organisms.
• Notice that an organism can feed on, or be eaten by, multiple species in a food web.

This quiz explores the characteristics of aquariums as ecosystems, focusing on communities, habitats, and the role of biodiversity. It also covers concepts like succession and the importance of decomposers and trophic levels. Test your understanding of these vital ecological principles!