Interactions in Ecosystems

Interactions in Ecosystems

• Biotic (living) and abiotic (non-living) factors influence organism survival and growth.
• Ecosystem productivity depends on biotic and abiotic factors.
• Symbiosis involves long-term relationships (mutualistic, commensal, parasitic).
• Competition occurs when species use shared, limited resources. (Example: crabs and snails competing for hiding places)
• Predation involves one species consuming another. (Example: seagulls eating fish)
• Mutualism benefits both species. (Example: clownfish cleaning anemones, benefiting both)
• Commensalism benefits one species without affecting the other. (Example: jackfish swimming with sharks)
• Parasitism benefits one species and harms the other. (Example: leeches feeding on fish blood)
• Interactions: a complex web of interdependence between organisms and their environment.

Estuaries and Mangroves

• Mangroves are coastal trees/shrubs, mainly tropical/subtropical, adapted to salt and oxygen-poor environments. Adaptations include specialized roots and leaves.
• Mangroves provide coastal protection, wildlife shelter, and water filtration.
• Estuaries are freshwater/saltwater mixing zones (river mouths, inlets, bays, sounds, marshes, mangrove forests).
• Estuaries and Coastal Wetlands are highly productive due to available light and nutrients.
• Seagrass beds support diverse marine life, stabilize shorelines, and reduce waves.
• Brackish water is a mixture of freshwater and saltwater.
• Estuaries provide valuable ecological and economic services for humans (water quality, food, timber, recreation, storm damage reduction, erosion).
• Coral Reefs, Estuaries and Mangroves are high biodiversity centers harboring many organisms, notably a significant fraction of marine species and serve as nurseries.
• Estuaries characteristics: daily tidal rhythms, freshwater runoff, salinity fluctuations, diverse substrates.
• Four types: drowned river mouths (Chesapeake Bay), fjords (glacially carved), barrier-built, tectonic.
• Mangroves and vascular plants can remove excess salt.
• Invertebrates (barnacles, mussels, periwinkles, fiddler crabs, marsh snails, shrimp, clams, worms)
• Seasonal fish species (striped bass, bluefish, menhaden, surfperch).
• Birds like herons, sandpipers, pelicans, ospreys, ducks, geese.
• Mammals like manatees.
• Threats: development, dredging, sediment disposal, toxic runoff.
• Estuaries support adaptations for tolerating varying salinity (invertebrates like oysters, phytoplankton, zooplankton that migrate with tides).
• Conservation efforts: National Estuarine Research Reserve System.

Ocean Salinity

• Ocean salinity is the total dissolved inorganic solids in seawater. (97.2% of Earth's surface water is marine).
• Salinity ranges between 3.3% and 3.7%. Variability caused by precipitation, evaporation, and freshwater runoff.
• Ocean salts primarily come from weathering of rocks, groundwater, river runoff, volcanic activity and tectonic movements.
• The majority of the components from ocean water come from tectonic movement.
• The most abundant salt is sodium chloride (NaCl). Other major salts include chloride, sodium, sulfate, magnesium, calcium, potassium, and bicarbonate.
• Ocean water has chemical equilibrium, meaning salt proportions remain relatively constant.
• Ocean (seawater) is about 96.5% water and 3.5% dissolved substances.

Plankton and Zooplankton

• Plankton are microscopic plant-like organisms performing photosynthesis.
• Zooplankton are animal-like organisms drifting in water, some growing into larger animals.
• Movement: Plankton use flagella, cilia, or spines for movement and buoyancy.
• Nutrition: Zooplankton may consume other organisms.
• Sunlight: Plankton primarily reside near the surface for optimal photosynthesis, moving vertically to find food, avoid predators, and manage a position in the food chain.
• Photosynthesis: Plankton use chlorophyll to convert sunlight into energy.

Energy Flow

• Autotrophs harness energy via photosynthesis.
• Producers trap less than 2% of solar energy.
• Trophic levels represent each step in a food chain or web.
• Producers (autotrophs): 1st trophic level, create their food via light or chemical energy.
• Consumers (heterotrophs): 2nd, 3rd etc. trophic levels, feeding on other organisms. (1st level=primary consumer, herbivore, 2nd level=secondary consumer, carnivore or omnivore, 3rd level=tertiary consumer, carnivore or omnivore)
• Decomposers (detritivores) break down dead organisms returning nutrients to the environment.
• Food chain: shows energy transfer from sun through organisms.
• Food web: interconnected food chains.

Levels of Organization

• Levels of organization: individual, population, community, ecosystem, biome, biosphere.
• Individual: single organism of a species.
• Population: group of same-species organisms.
• Community: group of different populations.
• Ecosystem: all organisms and their abiotic surroundings.
• Biome: ecosystems with similar climate & dominant communities.
• Biosphere: all life on Earth.

Biotic and Abiotic Factors

• Biotic factors: living influences on an organism. (predators, prey, competitors).
• Abiotic factors: non-living aspects influencing survival (climate, soil type, salinity, temperature, precipitation).
• Interactions of biotic and abiotic factors determine organism survival and ecosystem productivity.

Organisms, Habitats and Niches

• Organism: individual living thing (single-celled or multi-celled).
• Habitat: an organism's living area.
• Niche: organism's role in its environment (physical & biological conditions, its use of them). (Example: Bullfrog-eats insects, worms, and lives near water)

Ocean Zones

• Intertidal zone: between high/low tide.
• Neritic zone: low tide to continental shelf.
• Benthic zone: ocean seafloor.
• Pelagic zone: open water portion of the ocean (vertical regions).
• Oceanic zone: open ocean waters.
• Epipelagic: upper part of oceanic zone, sunlight.
• Mesopelagic: middle part of oceanic zone, light penetration weaker.
• Bathypelagic: deeper oceanic zone
• Abyssal Pelagic: even deeper, seabed
• Hadalpelagic: deepest part in ocean trenches
• Light Zones: photic (sunlit, highest productivity), disphotic (twilight), aphotic (dark).
• Ocean depth increases: temperature decreases, pressure increases, salinity generally more stable or slightly increasing.