How a Seaweed's Growth and Shape Change Over Time

Jenn Hoskins
10th March, 2024

How a Seaweed's Growth and Shape Change Over Time

Image Source: Natural Science News, 2024

Key Findings

  • In southwest UK, the kelp Saccorhiza polyschides has become more abundant, especially in late summer
  • This kelp provides important habitats and contributes to marine productivity
  • Its short, yearly life cycle differs from other long-lived kelps, affecting local biodiversity
In the coastal waters of the southwest UK, scientists from the Marine Biological Association of the UK have been closely examining a type of kelp known as Saccorhiza polyschides. This large brown macroalga is not just a plant; it's a critical part of the marine environment, providing habitat and food for a variety of marine life. Recently, there's been a noticeable increase in its presence along the southern UK coastlines, which has raised questions about its ecological role and how it might be responding to environmental changes[1]. Kelps are known to be sensitive to their surroundings, particularly to changes in temperature, light, and water movement. These factors can significantly affect their growth and survival. In the case of Saccorhiza polyschides, scientists have observed a pattern of growth that seems to align with seasonal changes. During the late summer months, this kelp becomes a dominant feature on both intertidal and subtidal reefs, with its biomass reaching impressive levels, sometimes exceeding 13,000 grams per square meter. This pattern is important because kelps like Saccorhiza polyschides contribute to the coastal carbon cycle, as they absorb carbon dioxide during photosynthesis and can store large amounts of carbon in their tissues. Studies have shown that the productivity and detritus production from kelp species like Saccharina latissima play a significant role in the coastal carbon cycle[2]. Moreover, kelp forests globally are estimated to provide substantial ecological and economic benefits, including fisheries production, nutrient cycling, and carbon sequestration[3]. However, the life strategy of Saccorhiza polyschides is quite different from that of other kelp species. It is pseudo-annual, meaning it goes through its entire life cycle in roughly a year, unlike the perennial kelps that live for many years. This difference could have implications for the ecosystem services kelps provide, as well as for the overall biodiversity and community composition of the habitats they form. The study's findings underscore the importance of monitoring and understanding the population dynamics of kelp species. This is particularly crucial as climate change continues to affect marine environments. Previous research has indicated that kelp populations, like Saccharina latissima, have been declining in some areas while increasing in others, likely due to climate-induced changes[4]. Moreover, across Australia, many marine species have been experiencing population declines following heatwaves, with significant impacts on marine ecosystems[5]. To collect their data, researchers conducted detailed intertidal surveys during spring low tides at various sites in Plymouth Sound. They measured the density, cover, age, biomass, and morphology of Saccorhiza polyschides. They also compared these intertidal populations with those found in subtidal reefs to get a more complete picture of the species' demographics. The research by the Marine Biological Association of the UK is vital for several reasons. First, it helps fill a regional knowledge gap about the ecological functioning of Saccorhiza polyschides within its central range. Second, it provides a baseline for future studies to detect changes in kelp populations and understand the potential impacts of environmental stressors, including ocean warming. Lastly, it highlights the need for high-resolution cross-habitat surveys to monitor the health of these important marine ecosystems accurately. In conclusion, Saccorhiza polyschides is proving to be a key species in the marine habitats of the southwest UK. Its abundance and seasonal growth patterns contribute significantly to the local biodiversity and the broader marine environment. As the planet continues to experience climate change, studies like this one are essential in helping us understand how marine ecosystems are responding and what we might expect in the future. The work of these scientists is a critical step in managing and conserving our valuable coastal ecosystems for generations to come.

EcologyPlant ScienceMarine Biology


Main Study

1) Spatiotemporal variability in population demography and morphology of the habitat-forming macroalga Saccorhiza polyschides in the Western English Channel.

Published 8th March, 2024

Related Studies

2) Seasonal and spatial variability in rates of primary production and detritus release by intertidal stands of Laminaria digitata and Saccharina latissima on wave-exposed shores in the northeast Atlantic.

3) The value of ecosystem services in global marine kelp forests.

4) The sugar kelp Saccharina latissima I: recent advances in a changing climate.

5) Continent-wide declines in shallow reef life over a decade of ocean warming.

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