eco 13

Marine Ecosystems Overview

• Classification: Marine ecosystems are classified based on several criteria:

  • Depth of water

  • Distance from the shore

  • Depth of sunlight penetration

• Major Types: Two main types:

  • Coastal ecosystems: Areas where land meets sea (e.g., seashores)

  • Open ocean ecosystems

Open Ocean Ecosystems

• Pelagic vs. Benthic Divisions:

  • Pelagic Division: Refers to the water column and organisms living in the water.

  • Benthic Division: Refers to the seabed and organisms living on or near the ocean floor.

Coastal Ecosystems

• Intertidal Zone:

  • The area between low tide and high tide levels where land and sea meet.

  • Experiences alternating submersion and exposure due to tidal cycles.

• Organism Adaptations: Organisms in this zone must adapt to:

  • Variations in seawater availability,

  • Temperature fluctuations,

  • Oxygen availability,

  • Salinity variations,

  • Mechanical forces from wave action.

• Rocky Shores:

  • Characterized by fixed substratum of rocks.

  • Dominated by sessile species (e.g., seaweeds, barnacles, mussels).

  • Organisms that are relatively sessile include:

  • Limpets: Slow-moving but can relocate.

  • Sea Anemones: Typically attached but can move if necessary.

• Competition for Space:

  • High competition for space among sessile organisms.

  • Disturbances (e.g., storms) create gaps that are quickly colonized by other species.

• Zonation of Rocky Shores:

  • Supralittoral Zone:

  • Only inundated during high spring tides.

  • Organisms here experience infrequent seawater contact.

  • Upper Littoral Zone:

  • Submerged only during peak tides; organisms must survive long periods out of water.

  • Mid Littoral Zone:

  • Approximately 50% time submerged and 50% time above water, hosting a different suite of organisms.

  • Lower Littoral Zone:

  • Exposed only during lowest tides, organisms remain mostly submerged.

Sandy Shores

• Characteristics:

  • Consist of soft substratum that shifts with wave action.

  • Life is primarily found buried within sediments.

• Adaptations of Organisms:

  • Some organisms, like worms, have permanent burrows; others form temporary burrows to escape disturbance.

• Strand Line:

  • Location where debris such as dead marine life accumulates at the high tide mark, providing feeding opportunities for scavengers.

• **Feeding Activity: **

  • Many species feed at night to avoid predators and benefit from cooler temperatures and lack of sun.

• Zonation:

  • Similar zonation occurs on sandy shores as on rocky shores based on species’ adaptation tolerances.

Role of Oceans in Ecosystem Functioning

• Climate Regulation: Oceans contribute significantly to:

  • Rainfall through evaporation and atmospheric circulation.

  • Global climate and wind pattern regulation based on ocean temperatures.

• Oxygen Production: Marine algae, including diatoms and phytoplankton, are crucial for:

  • Oxygen generation through photosynthesis.

  • Carbon dioxide absorption.

Open Ocean Ecosystems: Expansion

• Neritic and Oceanic Provinces:

  • Neritic Province: Extends from the seashore to the edge of the continental shelf (approximately 200 meters depth).

  • Oceanic Province: Encompasses waters beyond the continental shelf.

• Organism Abundance: The neritic province has high organism concentrations due to:

  • High sunlight penetration.

  • Nutrient input from rivers.

Coral Reefs

• Distribution: Found primarily in tropical and subtropical zones (between 30°N and 30°S).

• Ecological Role:

  • Highly productive with immense species diversity.

  • Corals provide habitats analogous to terrestrial forests.

• Coral-Microalgae Symbiosis:

  • Coral polyps host photosynthetic zooxanthellae that provide carbohydrates; corals offer protection and nutrients.

• Vulnerability:

  • Sensitive to temperature fluctuations; coral bleaching occurs when zooxanthellae are expelled due to stress.

Open Ocean Zones

• Epipelagic Zone:

  • Upper sunlit layer where photosynthesis occurs (up to 200 meters).

  • Majority of marine life found here; subject to wind movement.

• Mesopelagic Zone:

  • Ranges from 200-1000 meters.

  • Insufficient light for photosynthesis; organisms are primarily carnivorous and may migrate to the surface at night.

• Bathypelagic Zone:

  • Predominantly dark; organisms often exhibit bioluminescence.

  • Adaptations include large mouths and thin bodies to optimize food capture and minimize energy expenditure.

• Abyssopelagic Zone:

  • Deepest part of the ocean with extreme pressure and cold temperatures.

  • Organisms here often rely on scavenging.

Ocean Currents

• Surface Currents:

  • Influenced by wind and Coriolis force:

  • Clockwise in the Northern Hemisphere.

  • Counterclockwise in the Southern Hemisphere.

  • Accurate mapping of currents is essential for understanding marine biology and ecology.

• Deep Water Circulation:

  • Driven by density differences due to temperature and salinity variations (thermohaline circulation).

  • Cold, dense waters sink in polar regions (e.g., North Atlantic Deepwater) and move toward the equator, influencing global climate.

Impact of Pollutants

• Contaminants locked in water during sinking can resurface after extended periods, highlighting concerns regarding oceanic pollution as well as its implications for climate change.