In the complex and vibrant world beneath the ocean’s surface, the relationship between biodiversity and ecosystem function has long fascinated ecologists. Traditional ecological thought emphasized species richness—the sheer number of species—as the primary driver of ecosystem health and productivity. However, a groundbreaking new study published in Nature Communications challenges this paradigm, revealing that species abundances—the proportional representation of each species—may have a more profound effect on how marine ecosystems function.
The research, conducted by Yan, Morais, and Bellwood, delves deep into the intricate connections between marine fish biodiversity and ecosystem functioning across a range of diverse ocean habitats. By rigorously analyzing data from coral reefs and other marine ecosystems, the team identified a crucial distinction: the relative abundance of species within a community exerts a greater influence on ecosystem processes than the simple count of species alone. This nuanced understanding has the potential to reshape conservation strategies and ecological models worldwide.
For decades, biodiversity scientists have used species richness as a key metric to assess ecosystem health. The idea is intuitive—more species generally translate to more functions being fulfilled, such as nutrient cycling, habitat construction, and energy flow. Yet, this new study reveals that the internal composition of the community, specifically the dominance or rarity of certain species, substantially modulates these functions. When some species are abundant, their ecological roles overshadow the presence of less common species, influencing the overall productivity and stability of the ecosystem.
Yan and colleagues employed sophisticated statistical models and extensive databases of marine fish assemblages, spanning multiple geographic zones and ecological gradients. Their approach combined species richness measurements with richly detailed abundance data, allowing for a multi-dimensional view of biodiversity. This methodological advancement was critical for teasing apart how different facets of biodiversity contribute to ecosystem function.
Their analysis showed that changes in species abundance patterns often had a stronger correlation with ecosystem metrics such as biomass production, herbivory rates, and trophic interactions than did changes in species richness. For example, reefs where a few herbivorous fish species dominate were found to exhibit higher rates of algal control and coral growth, compared to reefs hosting a greater number of species in roughly equal abundance but with fewer dominant players.
This finding challenges conventional wisdom in marine ecology by illustrating that it is not just the presence or absence of species that matters but how abundant each species is in relation to others. Dominant species can drive key ecosystem functions disproportionately, while rare species, although contributing to overall diversity, may play smaller functional roles. Such insights underscore the need for ecosystem management to consider not only how many species are present but how population dynamics influence ecological outcomes.
The implications for conservation and ecosystem management are profound. Current conservation policies that prioritize species preservation and biodiversity hotspots might be overlooking critical aspects of species abundance structures. Protecting species that fulfill major ecological roles in significant numbers could prove more effective in maintaining ecosystem resilience than efforts solely aimed at increasing species counts.
Moreover, the study highlights the complex interplay between biodiversity components—richness, abundance, and evenness—and how these shape the resilience and functionality of marine ecosystems facing escalating environmental pressures such as climate change, overfishing, and habitat degradation. Such pressures often disrupt species abundances, which in turn can cascade into diminished ecosystem services.
Another challenge underscored by the research is understanding the mechanisms by which species abundances fluctuate and how these changes feed back into ecosystem processes. Factors such as predation, competition, recruitment, and environmental filters dynamically shape community composition, influencing which species become dominant. The authors suggest that future studies integrating these ecological mechanisms will be crucial to develop predictive models for biodiversity-ecosystem function relationships.
Importantly, this work also broadens the theoretical frameworks used to study ecosystem functioning. Historically, models have often treated species as equivalent units, ignoring differences in abundance and biomass. By factoring in species dominance and rarity, Yan et al. provide a more realistic and applicable framework that better captures the complexity of natural marine communities.
In addition to advancing theoretical ecology, this research offers tangible pathways for applied marine science. Effective restoration practices could prioritize the reintroduction or protection of functionally important species in adequate numbers to rapidly restore ecosystem functioning. Likewise, fisheries management might benefit from monitoring not just quotas but also community composition changes that signal shifts in ecosystem health.
The study also opens avenues for exploring how biodiversity facets influence ecosystem multifunctionality—the simultaneous performance of multiple ecological processes. Since dominant species tend to specialize in particular functions, maintaining a balance between species richness and abundance could be vital to sustain multifunctionality, ensuring ecosystems continue to provide diverse services such as fisheries, coastal protection, and carbon sequestration.
Furthermore, the spatial dimension of biodiversity and abundance patterns is highlighted. Marine habitats often exhibit patchy distributions where certain species flourish in localized hotspots, creating heterogeneity in ecosystem functioning. Recognizing this spatial variability provides insights relevant for marine protected areas and spatial planning initiatives.
Taken together, the findings by Yan, Morais, and Bellwood represent a significant leap forward toward unraveling the nuances of biodiversity-ecosystem function relationships in marine systems. They compel ecologists, conservationists, and policymakers to rethink biodiversity beyond simple species counts, emphasizing abundance and dominance as pivotal components.
As marine ecosystems worldwide continue to face unprecedented challenges, this fresh perspective equips us with better tools to predict and mitigate ecological change. Embracing the complexity of species abundance offers hope for more resilient ocean futures, where the vibrant tapestry of marine life can sustain both ecological integrity and human well-being.
This paradigm shift in biodiversity science holds promise extending beyond marine environments, suggesting that abundance patterns may play similarly crucial roles in terrestrial and freshwater ecosystems. Ultimately, such insights advance our fundamental understanding of life’s interconnections, pushing the boundaries of ecosystem ecology and conservation biology.
Subject of Research: Biodiversity-ecosystem function relationships in marine fishes focusing on species abundances versus species richness.
Article Title: Species abundances surpass richness effects in the biodiversity-ecosystem function relationship across marine fishes.
Article References:
Yan, H.F., Morais, R.A. & Bellwood, D.R. Species abundances surpass richness effects in the biodiversity-ecosystem function relationship across marine fishes. Nat Commun 16, 7789 (2025). https://doi.org/10.1038/s41467-025-63210-x
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