Interactions in Marine Ecosystems Notes

Chapter 3: Interactions in Marine Ecosystems

3.1 Interactions

  • Ecological Interactions: Relationships between organisms in a community.

    • Symbiosis: Close relationship between species.

    • Symbiont: Smaller organism benefiting from the relationship.

    • Host: Larger organism providing benefits to the symbiont.

Types of Symbiosis

  • Parasitism: Symbiont benefits, host is harmed.

    • Example: Copepods (sea lice) and marine fish.

    • Copepods are ectoparasites, living on the host's exterior, feeding on mucus, tissue, and blood.

    • Consequences of high infestation include:

    • Host death if vital areas are affected.

    • Reduced growth rates and biomass loss at lower levels of infestation.

  • Commensalism: Symbiont benefits, host remains unaffected.

    • Example: Remora fish and manta rays.

    • Remora attaches to manta rays, gaining transportation while causing no harm to the ray.

  • Mutualism: Both organisms benefit.

    • Example: Boxer crabs and anemones.

    • Crabs use anemones for defense; anemones gain food access.

3.2 Feeding Relationships

  • Producers: Organisms that make their own food (autotrophs); includes green plants, algae, and bacteria.

  • Consumers: Organisms that obtain energy from other organisms (heterotrophs).

  • Decomposers: Break down organic material and recycle nutrients.

Trophic Levels

  • Primary Consumers (Herbivores): Feed on plant material.

  • Secondary Consumers (Carnivores): Feed on herbivores.

  • Tertiary Consumers: Feed on secondary consumers.

  • Quaternary Consumers: Feed on tertiary consumers.

  • Apex Predators: Top of the food chain, no natural predators.

Predation

  • Predator: Organism that hunts and eats others.

    • Examples: Sharks, carnivorous fish.

  • Prey: Organism eaten by predators, often has defense mechanisms such as camouflage or spines.

  • Coevolution observed in predator-prey dynamics.

Food Chains and Food Webs

  • Food Chain: Linear feeding relationship (producer to consumer).

  • Food Web: Complex interconnections of feeding relationships.

    • Arrows represent energy transfer direction.

Productivity

  • Primary Productivity: Rate of new biomass production by autotrophs.

    • Photosynthetic Autotrophs: Convert light to energy in photic zone.

    • Chemosynthetic Autotrophs: Use inorganic reactions to form organic compounds, e.g., at hydrothermal vents.

Photosynthesis and Factors Affecting It

  • Green plants use CO2 and H2O to produce glucose, powered by sunlight via chlorophyll.

  • Limiting Factors:

    • Temperature: Stable in marine environments.

    • CO2: Low fluctuation due to mixing oceans.

    • Light Intensity: Affects photosynthesis rate; decreases with depth.

Chemosynthesis vs. Photosynthesis

  • Both: Use CO2, produce sugars, support metabolism.

  • Chemosynthesis: Occurs in aphotic zones, uses inorganic compounds (H2S).

  • Photosynthesis: Requires light, occurs in photic zones, produces O2.

Energy Transfer

  • Energy inefficiencies occur at each trophic level (avg. ~10%).

  • Energy calculations:

    • C = P + R + F + U (C = consumed energy, R = respiration, F = feces, U = urine).

Ecological Pyramids

  • Pyramid of Numbers, Biomass, and Energy:

    • Illustrate the abundance and energy available at each trophic level.

    • Usually pyramidal shape, but can be inverted in specific scenarios (e.g., high producer consumption).

3.3 Nutrient Cycles

  • Nutrient Cycles: Movement of essential nutrients through the ecosystem, e.g., Carbon, Nitrogen.

    • Biologic Role: Nutrients are crucial for cellular processes (e.g., nitrogen for DNA).

    • Sources: Gaseous, sedimentary, or dissolved forms in water.

Processes Replenishing Nutrients

  1. Dissolving of Atmospheric Gases: CO2 and N2 enter oceans via diffusion.

  2. Upwelling: Nutrient-rich deep water replaces surface water, enhancing productivity.

  3. Run-off: Nutrients leach into oceans from soil.

  4. Tectonic Activity: Nutrients from volcanic eruptions and hydrothermal vents replenish ocean nutrients.

  5. Excretion and Decomposition: Animal waste and decomposing organisms release nutrients back to the ecosystem.

Carbon Cycle

  • Carbon Sources and Sinks: Movement of carbon through the environment via several processes, including respiration and photosynthesis.

  • Long-term storage in sediments and fossil fuels, recycling through biological processes.

Ocean Acidification

  • Higher CO2 levels lead to decreased carbonate ion availability, impacting organism calcification.

Prevention Ideas for Ocean Acidification

  • Ocean Seeding: Iron fertilization to promote phytoplankton productivity, though potential long-term effects remain uncertain.

Chapter 3: Interactions in Marine Ecosystems
3.1 Interactions

  • Ecological Interactions: Relationships between organisms in a community.- Symbiosis: Close relationship between species.

    • Symbiont: Smaller organism benefiting from the relationship.

    • Host: Larger organism providing benefits to the symbiont.

Types of Symbiosis

  • Parasitism: Symbiont benefits, host is harmed.

    • Example: Copepods (sea lice) and marine fish.

    • Copepods are ectoparasites, living on the host's exterior, feeding on mucus, tissue, and blood.

    • Consequences of high infestation include:

      • Host death if vital areas are affected.

      • Reduced growth rates and biomass loss at lower levels of infestation.

  • Commensalism: Symbiont benefits, host remains unaffected.

    • Example: Remora fish and manta rays.

    • Remora attaches to manta rays, gaining transportation while causing no harm to the ray.

  • Mutualism: Both organisms benefit.

    • Example: Boxer crabs and anemones.

    • Crabs use anemones for defense; anemones gain food access.

3.2 Feeding Relationships

  • Producers: Organisms that make their own food (autotrophs); includes green plants, algae, and bacteria.

  • Consumers: Organisms that obtain energy from other organisms (heterotrophs).

  • Decomposers: Break down organic material and recycle nutrients.

Trophic Levels

  • Primary Consumers (Herbivores): Feed on plant material.

  • Secondary Consumers (Carnivores): Feed on herbivores.

  • Tertiary Consumers: Feed on secondary consumers.

  • Quaternary Consumers: Feed on tertiary consumers.

  • Apex Predators: Top of the food chain, no natural predators.

Predation

  • Predator: Organism that hunts and eats others.- Examples: Sharks, carnivorous fish.

  • Prey: Organism eaten by predators, often has defense mechanisms such as camouflage or spines.

  • Coevolution observed in predator-prey dynamics.

Food Chains and Food Webs

  • Food Chain: Linear feeding relationship (producer to consumer).

  • Food Web: Complex interconnections of feeding relationships.- Arrows represent energy transfer direction.

Productivity

  • Primary Productivity: Rate of new biomass production by autotrophs.- Photosynthetic Autotrophs: Convert light to energy in photic zone.

    • Chemosynthetic Autotrophs: Use inorganic reactions to form organic compounds, e.g., at hydrothermal vents.

Photosynthesis and Factors Affecting It

  • Green plants use CO2 and H2O to produce glucose, powered by sunlight via chlorophyll.

  • Limiting Factors: - Temperature: Stable in marine environments.

    • CO2: Low fluctuation due to mixing oceans.

    • Light Intensity: Affects photosynthesis rate; decreases with depth.

Chemosynthesis vs. Photosynthesis

  • Both: Use CO2, produce sugars, support metabolism.

  • Chemosynthesis: Occurs in aphotic zones, uses inorganic compounds (H2S).

  • Photosynthesis: Requires light, occurs in photic zones, produces O2.

Energy Transfer

  • Energy inefficiencies occur at each trophic level (avg. ~10%).

  • Energy calculations:- C = P + R + F + U (C = consumed energy, R = respiration, F = feces, U = urine).

Ecological Pyramids

  • Pyramid of Numbers, Biomass, and Energy:- Illustrate the abundance and energy available at each trophic level.

    • Usually pyramidal shape, but can be inverted in specific scenarios (e.g., high producer consumption).

3.3 Nutrient Cycles

  • Nutrient Cycles: Movement of essential nutrients through the ecosystem, e.g., Carbon, Nitrogen.- Biologic Role: Nutrients are crucial for cellular processes (e.g., nitrogen for DNA).

    • Sources: Gaseous, sedimentary, or dissolved forms in water.

Processes Replenishing Nutrients

  1. Dissolving of Atmospheric Gases: CO2 and N2 enter oceans via diffusion.

  2. Upwelling: Nutrient-rich deep water replaces surface water, enhancing productivity.

  3. Run-off: Nutrients leach into oceans from soil.

  4. Tectonic Activity: Nutrients from volcanic eruptions and hydrothermal vents replenish ocean nutrients.

  5. Excretion and Decomposition: Animal waste and decomposing organisms release nutrients back to the ecosystem.

Carbon Cycle

  • Carbon Sources and Sinks: Movement of carbon through the environment via several processes, including respiration and photosynthesis.

  • Long-term storage in sediments and fossil fuels, recycling through biological processes.

Ocean Acidification

  • Higher CO2 levels lead to decreased carbonate ion availability, impacting organism calcification.

Prevention Ideas for Ocean Acidification

  • Ocean Seeding: Iron fertilization to promote phytoplankton productivity, though potential long-term effects remain uncertain.

Practice Questions

  1. Define symbiosis and list its three types. Provide an example for each type.

  2. Describe how energy transfer occurs across trophic levels. What is the average percentage of energy transferred from one level to the next?

  3. Explain the difference between chemosynthesis and photosynthesis.

  4. What role do decomposers play in marine ecosystems?

  5. Discuss the impact of ocean acidification on marine organisms.