How Do Changes In Tidal Amplitude And Wave Direction Caused By The El Niño-Southern Oscillation (ENSO) Affect The Distribution And Abundance Of Juvenile Olympia Oysters (Ostrea Lurida) In A Mixed Sand-gravel Habitat In A Temperate Coastal Embayment?

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The El Niño-Southern Oscillation (ENSO) influences the distribution and abundance of juvenile Olympia oysters (Ostrea lurida) in a mixed sand-gravel habitat through changes in tidal amplitude and wave direction. Here's a structured summary of the effects:

  1. Tidal Amplitude Changes:

    • El Niño Phase: Typically brings higher tidal amplitudes, increasing submersion duration in the intertidal zone. This can enhance nutrient availability but may also stress oysters through prolonged submersion and warmer waters.
    • La Niña Phase: Often results in lower tidal amplitudes, potentially exposing oysters to air for longer periods, increasing thermal and desiccation stress.

  2. Wave Direction and Sediment Transport:

    • Changes in wave direction during ENSO events can alter sediment distribution. Increased wave energy may erode certain areas, potentially smothering oysters with sediment or exposing them if sediment is removed. This affects substrate suitability for settlement and survival.

  3. Habitat and Ecological Impacts:

    • Distribution: Shifts in tidal and wave patterns can alter suitable habitats, forcing oysters to relocate. Areas may become more or less favorable depending on sediment changes and environmental conditions.
    • Abundance: Affected by habitat availability, predation, competition, and physiological stress. ENSO events can lead to either an increase or decrease in oyster populations based on how these factors interplay.

  4. Conclusion:

    • ENSO-driven changes in tides and waves create dynamic shifts in the physical environment, influencing the ecological habitat of juvenile Olympia oysters. These changes can lead to alterations in both their distribution and abundance as they adapt to the evolving conditions.

In essence, ENSO-induced environmental changes challenge the resilience of juvenile Olympia oysters, highlighting the complex interplay between physical and biological factors in shaping their populations.