Seagrasses pt. 2 & Kelp

Announcements

  • Third Check-in Reminder: Submit third check-in today.
    • Select any peer-reviewed article and summarize how you'll use it in your project.
    • A few sentences should suffice if you are familiar with the paper.
  • Group Collaboration: Ensure you're actively engaging with your project group due to upcoming peer evaluations.

Importance of Seagrass

  • Value of Seagrass Ecosystems: Estimated value of over $555 billion due to their ecological services.
  • Human Interaction: Coastal activities significantly affect seagrass beds, especially from boating activities.
    • Example: Boats running aground can destroy large areas of continuous seagrass, leading to patchiness.

Seagrass Recovery Dynamics

  • Continuous vs. Patchy Seagrass:
    • Continuous patches are likely to have higher reproductive success compared to patchy ones, influenced by conditions such as nearby disturbances (e.g. boats).
  • Factors Impacting Seagrass:
    • Sedimentation
    • Boat wakes causing disturbances
    • Coastal construction contributing to nutrient influx and pollution
    • Overfishing affecting species reliant on seagrass habitats (e.g. juvenile fishes, seahorses)
    • Extreme weather events related to climate change can destroy seagrass habitats.
    • Diseases: Seagrass wasting disease is known to affect populations heavily, especially in regions like Florida.

Consequences of Seagrass Loss

  • Habitat Loss: Reduced biodiversity due to the loss of habitats for various marine species.
  • Carbon Sequestration: Loss of seagrass leads to decreased ability to store carbon, impacting ocean acidification.
  • Fishery Decline: Essential fish species may relocate, leading to declines in both recreational and commercial fisheries.
  • Coastal Instability: Seagrass stabilizes sediment; loss can lead to increased erosion.

Grazing Dynamics in Seagrass Beds

  • Grazers Impact on Health of Seagrass: Presence of grazers (like crabs and sea urchins) influences health:
    • Without predators (e.g. sea otters), grazer populations can explode, leading to overgrazing and decreased health of seagrass beds.

Kelp Ecology

  • Kelp Habitat Structure:
    • Structure includes holdfasts, stipes, blades, and pneumatocysts.
    • Found mostly in cold, nutrient-rich waters, particularly in regions with upwelling favorable for growth.
  • Zonation Factors:
    • Light availability is the main factor influencing the distribution of kelp species.
    • Nutrients, temperature, and wave action also affect growth and species diversity in kelp forests.

Types of Kelp Species

  • Example Species:
    • Feather Boa Kelp: Shallow water, branched structure.
    • Laminaria: Non-branched, single blade structure, deeper water.
    • Bull Kelp: Large nematocyst for buoyancy, common in California.
    • Elk Kelp: Antler-like structure, needs rocky substrate.

Kelp Reproduction and Community Interactions

  • Reproductive Phases:
    • Dominant phase is the sporophyte (what we typically see).
    • Gametophyte phase is crucial for fertilization.
  • Importance of Detritus: A significant part of kelp ecosystems, supporting numerous higher trophic levels.

Threats to Kelp Ecosystems

  • Overgrazing: Sea urchin population blooms, especially when predator balance (like sea otters) is disrupted, can lead to destruction of kelp forests.
  • Climate Change Impacts: Changes in water temperature and nutrient availability associated with climate phenomena (e.g. El Niño and La Niña) significantly affect kelp health and productivity.
  • Human Impact: Coastal pollution and habitat destruction from construction, fishing, and recreational activities pose serious threats to kelp forests.

Conservation Strategies

  • Marine Protected Areas: Establish zones that limit fishing and protect marine habitats to allow for recovery of ecosystems.
  • Awareness and Education: Importance of informing the public about the ecological roles of seagrasses and kelp beds, promoting engaged citizen science.
  • Restoration Techniques: Include strategies like kelp transplanting, seed banking, and reducing nutrient inflows to restore damaged ecosystems effectively.