Sensitivity of communities' trait-based indices to species selection

Area of Science:

• Marine ecology
• Ecosystem assessment
• Biodiversity informatics

Background:

• Trait-based indicators are valuable for assessing environmental impacts on marine communities.
• Data limitations, particularly regarding less-studied species, can introduce bias in these indicators.
• The influence of species selection methodology on trait-based indices requires thorough investigation.

Purpose of the Study:

• To evaluate the impact of species selection filters (occurrence, distribution, abundance) on trait-based indices.
• To identify biases in trait data availability and its representation of demersal communities.
• To assess the effect of excluding specific taxonomic groups, such as invertebrates, on community trait analyses.

Main Methods:

• Compiled 15 ecological traits for 246 demersal species from bottom-trawl surveys in the North-East Atlantic and Mediterranean Sea.
• Applied filters based on species occurrence, distribution, and abundance to assess selection bias.
• Analyzed the influence of species selection on community-level trait metrics and compared results with and without invertebrate data.

Main Results:

• Trait data exhibited a significant bias towards abundant, large, and commercially or conservation-relevant species.
• Species selection filters had a minor impact on overall community trait composition.
• Excluding invertebrate species substantially altered the outcomes of community trait analyses, revealing their critical role.

Conclusions:

• Trait data collection methods can introduce bias, overrepresenting certain species.
• Invertebrates play a crucial role in shaping community traits and should be included in analyses.
• Careful consideration of species selection is necessary for robust trait-based ecological assessments.