Studying biodiversity-ecosystem function relationships in experimental microcosms among islands

Area of Science:

• Ecology
• Microbiology
• Island Biogeography

Background:

• Island ecosystems offer unique insights into biodiversity.
• Factors influencing microbial biodiversity and ecosystem function on islands remain underexplored.
• Diatoms are key primary producers in aquatic ecosystems.

Purpose of the Study:

• To investigate the impact of environmental stress (salinity) and dispersal on diatom biodiversity and ecosystem productivity on Baltic Sea islands.
• To examine the relationship between diatom community structure (biodiversity, mean body size) and ecosystem productivity.
• To understand how environmental factors mediate biodiversity-ecosystem function relationships.

Main Methods:

• Field experiment using aquatic microcosms on five Baltic Sea islands.
• Manipulation of salinity levels to simulate environmental stress.
• Colonization of diatoms from the air.
• Structural Equation Models (SEM) to analyze interconnections between factors, biodiversity, and productivity (chlorophyll a).

Main Results:

• No direct relationship found between species richness/evenness and productivity.
• Ecosystem productivity increased with increasing mean body size of diatom species.
• Environmental stress (salinity) and wind exposure negatively impacted biodiversity metrics (richness, evenness).
• Productivity increased at higher salinity levels, despite reduced species richness.

Conclusions:

• Salinity acts as a strong abiotic filter, creating species-poor but productive communities at high levels.
• Mean community body size is a crucial trait mediating environmental effects on ecosystem productivity.
• Findings highlight the importance of considering community-level traits beyond species richness in biodiversity-ecosystem function studies.