Seagrass-bivalve facilitative interactions: Trait-mediated effects along an environmental gradient

Area of Science:

• Ecology
• Marine Biology
• Environmental Science

Background:

• Facilitative interactions are crucial for community structure and function.
• Lucinid bivalves and seagrasses engage in a vital mutualism, with seagrasses providing habitat and oxygen, and bivalves detoxifying sulfide-rich sediment.
• Understanding how these interactions respond to environmental changes is critical for ecological conservation.

Purpose of the Study:

• To investigate how the mutualism between Cymodocea nodosa seagrass and lucinid bivalves is affected by varying sediment organic matter content.
• To determine the relationship between sediment organic matter, lucinid bivalve abundance, and seagrass root traits.

Main Methods:

• A correlative approach was employed to statistically analyze associations.
• Data collected included sediment organic matter content, lucinid bivalve abundance, and seagrass root abundance and morphology.
• Comparisons were made between vegetated and bare areas, and along a gradient of organic matter content.

Main Results:

• Lucinid bivalve abundance was significantly higher in vegetated areas compared to bare areas.
• In vegetated areas, lucinid abundance decreased as sediment organic matter content increased.
• Increased organic matter led to reduced seagrass root abundance and less branched root morphology, diminishing habitat for lucinids.

Conclusions:

• Elevated sediment organic matter weakens the seagrass-lucinid mutualism by negatively impacting seagrass root structure.
• This disruption reduces the resilience of seagrass meadows to environmental disturbances, particularly those involving organic enrichment.
• Findings highlight the vulnerability of essential ecological interactions to anthropogenic impacts.