Decline in Kelp Forests Lowers Seaweed Diversity

Jenn Hoskins
11th March, 2024

Decline in Kelp Forests Lowers Seaweed Diversity

Image Source: Natural Science News, 2024

Key Findings

  • Study from Universidad de A Coruña shows kelp forest decline impacts species distribution
  • Traditional biodiversity measures (α-diversity) didn't show a difference between healthy and degraded kelp forests
  • Spatial diversity (β-diversity) was lower in degraded forests, indicating a loss of ecosystem complexity
Kelp forests are underwater ecosystems formed by large seaweeds (kelps) that are crucial for marine life, providing food and shelter for a diverse range of organisms. Recent research from the Universidad de A Coruña[1] has highlighted the importance of looking beyond traditional biodiversity measures when assessing the health of these vital habitats. The study focuses on the consequences of kelp forest decline on the marine species that inhabit these areas. Kelps are known as foundation species because they create a structured environment that supports other life forms. However, they are under threat from global changes, such as warming oceans and increased herbivory by fish, which can lead to the collapse of these forests. The study by researchers at the Universidad de A Coruña investigates how the decline of kelp canopies affects the diversity and distribution of the species living in the understorey—the layer of seaweed that grows beneath the kelp. The researchers conducted a year-long seasonal study comparing healthy kelp forests with those where the canopy had collapsed. They measured both α-diversity, which includes the total number of species (richness), the number of species per unit area (species density), and the Shannon index (a measure of species abundance and evenness); and β-diversity, which looks at the variation in species composition between different areas. The results showed that while α-diversity did not significantly differ between healthy and degraded reefs, β-diversity was notably lower in the degraded areas. This suggests that while the total number of species may remain the same, the way they are spatially distributed is affected by the loss of the kelp canopy. In degraded reefs, species were more homogeneously spread out, indicating a loss of complexity in these ecosystems. This study builds upon previous research[2] that found that artificial habitats might not be as biologically homogeneous as natural ones, challenging the idea that urbanization necessarily leads to a loss of biodiversity. It also aligns with findings[3] that canopy-forming species, like kelps, can influence the spatial distribution of other species by modifying environmental conditions. Furthermore, the research adds to our understanding of the impact of climate change on marine ecosystems. It supports the notion[4] that ocean warming and acidification are leading to the simplification of marine habitats, as seen with the loss of kelp forests and the failure of tropical corals to thrive in temperate zones under these conditions. The study's findings are significant because they underscore the importance of using multiple metrics, including β-diversity, to assess the health of ecosystems. Traditional α-diversity measures alone may not capture the full impact of environmental changes on marine biodiversity. By including spatially explicit approaches, scientists and conservationists can gain a more comprehensive understanding of how disturbances affect marine life. In conclusion, the research from the Universidad de A Coruña suggests that the loss of kelp forests might not be fully reflected by traditional biodiversity measures. The study reveals that the spatial arrangement of species, an aspect captured by β-diversity, is an important factor to consider when evaluating the consequences of kelp decline. This insight is crucial for the conservation and management of marine ecosystems, which are increasingly threatened by human activities and global environmental changes.

EcologyMarine Biology


Main Study

1) Kelp forests collapse reduces understorey seaweed β-diversity.

Published 8th March, 2024

Related Studies

2) Metrics matter: Multiple diversity metrics at different spatial scales are needed to understand species diversity in urban environments.

3) Foundation species canopies affect understory beta diversity differently depending on species mobility.

4) Simplification, not "tropicalization", of temperate marine ecosystems under ocean warming and acidification.

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