sea life

Salinity and Osmoregulation

  • Topic: Overview of salinity and osmoregulation to be included for exam preparation.

  • Key Definitions: Hyperosmotic, Hypoosmotic, Isoosmotic.

  • Organisms discussed:

    • Invertebrates

    • Sharks

    • Green fishes

  • Terminology: Anadromous, Catadromous, Diadromous.

  • Illustrations:

    • Anguilla anguilla (Catadromous eel from Lake Worth Lagoon)

    • Salmon (Anadromous).

Definitions of Migration Types

  • Anadromous: Marine organisms that migrate to freshwater to spawn; offspring are carried back to the sea.

  • Catadromous: Freshwater organisms that migrate to the sea to spawn, often relying on tidal movements.

  • Diadromous: Organisms with the ability to move freely between saltwater and freshwater without a connection to reproduction.

Marine Plants Overview

  • Importance of discussing marine plants (algae).

  • Kelp as an example of Brown algae; forms underwater forests beneficial for marine ecosystems.

  • Personal anecdote regarding initial encounter with kelp in California.

Algae vs. True Plants

  • Definition of macroalgae as large algae compared to true plants.

  • Structural Comparison:

    • Algae lack vascular systems (no transport mechanism like xylem/phloem in plants).

    • Algal holdfasts vs true plant roots: Holdfasts anchor without nutrient absorption.

    • Difference in structures: Stipes for algae vs stems for plants; fronds for algae vs leaves.

    • Gas Bladders in Sargassum for buoyancy (pneumatophores).

Types of Algae

  • Discussed major groups of algae and the transition to true plants, particularly focusing on seagrasses.

Phytoplankton

  • General Information:

    • Definition: Microscopic photosynthetic organisms that form the foundation of aquatic food webs.

    • They are responsible for global oxygen production and carbon fixation.

  • Reproduction:

    • Phytoplankton can double their population every day under optimal conditions.

  • Ecological Issues:

    • Quick reproduction can lead to algal blooms (e.g., Lake Okeechobee incident).

    • Impacts: Environmental shading, fish kills, tourism issues.

Main Groups of Phytoplankton

  • Chrysophytes (Gold algae)

    • Diatoms:

      • Characteristics: Shell made of silica (
        extSiO2ext{SiO}_2).

      • Major contributor to beach sand composition; important in technology (used in silicon transistors).

    • Coccolithophores:

      • Shells made of calcium carbonate (
        extCaCO3ext{CaCO}_3).

      • Role in maritime ecosystems and potential implications for marine acidity and reef health.

  • Pyrophytes (Dinoflagellates):

    • Zooxanthellae (mutualistic relationship with corals).

    • Example: Karenia brevis, which causes red tide in Florida.

      • Effects: Toxicity leading to fish kills and human health problems.

    • Bioluminescence: Some dinoflagellates emit light (similar to lightning bugs in some ecosystems).

    • Example: Gambierdiscus (causes ciguatera poisoning).

Benthic Algae vs Microalgae

  • Benthic Algae: Larger, these macroalgae are attached to the seabed.

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