Understanding disproportionately high densities of stream macroinvertebrates in size-density relationships

Autor(es)

Braga, Julia M. ; Mello, Jose L. S. ; Shimabukuro, Erika M. ; Venuso, Laura J. ; Guerra, Pedro P. B. ; Perkins, Daniel M. ; Saito, Victor S.

• Tipo de documento: Artigo Científico
• Fonte: Hydrobiologia; v. N/A, p. 16-pg., 2025-10-07.

Resumo

Metabolic scaling theory provides a framework to understand energy flows in ecosystems, predicting a negative relationship between body mass and density, where smaller species tend to occur in higher densities than larger ones. We assessed disproportionately high densities in tropical stream macroinvertebrates through size-density relationships (SDR), focusing on taxa exceeding expected densities for their body mass. We hypothesized that unique functional traits allow singular niche exploitation and reduced competition, resulting in high net energetic gains. To test this, we sampled Atlantic Forest stream communities monthly for over a year, estimating individual body mass via allometric equations. Positive SDR residuals indicated disproportionate densities, which we related to functional traits. As expected, size and density were negatively related, with some taxa showing greater density in time than predicted by their body mass. However, contrary to our hypothesis, functional uniqueness was not associated with higher densities, suggesting that traits alone may not drive disproportionate densities. Instead, disproportionate densities appeared in taxa with high redundancy with congenerics. Additionally, taxa with higher densities showed greater temporal variability, indicating a fluctuating dynamic of dense populations. Our results suggest that high densities could be linked to a combination of niche preemption and modification mechanisms of community assembly. (AU)

• Processo FAPESP: 23/08252-0 - A fenologia de insetos aquáticos em regiões tropicais - bolsa 2
• Beneficiário: Laura Joia Venuso
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
• Processo FAPESP: 23/00574-9 - O papel da montagem estocástica de comunidades na estrutura de tamanho de metacomunidades aquáticas sob mudança global
• Beneficiário: José Leonardo da Silva Mello
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 23/15982-5 - Entendendo a desproporcionalidade de macroinvertebrados aquáticos em relações biomassa-abundância em riachos de Mata Atlântica
• Beneficiário: Julia Maria Braga
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 24/02873-6 - Relação entre estabilidade e complexidade em redes ecológicas de comunidades de riachos em zonas tropicais e temperadas
• Beneficiário: Pedro Pontes Bueno Guerra
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 22/01452-1 - Entendendo o papel da estocasticidade na montagem de metacomunidades sob efeitos de mudanças globais
• Beneficiário: Victor Satoru Saito
• Modalidade de apoio: Auxílio à Pesquisa - Regular