Recruitment tolerance to increased temperature present across multiple kelp clades

Area of Science:

• Marine Ecology
• Climate Change Biology
• Phycology

Background:

• Kelp ecosystems are vital nearshore marine habitats, particularly in productive upwelling zones.
• Kelp populations face threats from rising ocean temperatures and declining nutrient levels due to climate change.
• Global climate change impacts on kelp may be modulated by regional temperature variability and species-specific responses.

Purpose of the Study:

• To investigate the effects of temperature and nutrient availability on the recruitment success of kelp sporophytes.
• To determine the primary environmental factor limiting kelp recruitment across different geographic regions.

Main Methods:

• Conducted culture experiments on 12 eastern Pacific kelp taxa from British Columbia, central California, and southern California.
• Exposed kelp to three nitrate levels (1, 5, and 10 μmol/L) and two temperatures (12°C and 18°C).
• Assessed sporophyte production as a measure of recruitment success.

Main Results:

• Sporophytes were consistently present at 12°C across all taxa and locations.
• Recruitment failure occurred exclusively at 18°C, irrespective of nitrate concentrations.
• Temperature was identified as the critical factor limiting kelp recruitment, overriding nutrient availability.

Conclusions:

• Increasing ocean temperatures pose a significant threat to kelp recruitment success globally.
• Species' capacity for acclimatization or adaptation to warmer temperatures may enhance kelp system resilience.
• Understanding regional temperature dynamics is crucial for predicting kelp population persistence under climate change.