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Nutrient loading and consumers: agents of change in open-coast macrophyte assemblages
1Department of Zoology, Oregon State University, Corvallis, OR 97331-2914, USA. nielsenk@science.oregonstate.edu
Summary
Coastal ecosystems are changing due to human activities. Nutrient increases boost macrophyte growth in wave-exposed tide pools, but abundant consumers reduce plant diversity.
Area of Science:
- Marine ecology
- Coastal ecosystem dynamics
- Nutrient cycling
Background:
- Human activities alter coastal nutrient regimes and consumer abundance.
- Tide pool ecosystems exhibit complex interactions between nutrients, consumers, and macrophytes.
- Wave exposure influences nutrient loading and consumer efficiency.
Purpose of the Study:
- To investigate the effects of nutrient enrichment and consumer pressure on macrophyte communities in coastal tide pools.
- To compare responses in wave-exposed versus wave-protected sites.
- To predict potential impacts of climate change on coastal macrophyte assemblages.
Main Methods:
- Field experiment in an open-coast, upwelling ecosystem.
- Manipulation of nutrient supply and consumer abundance.
- Comparison of macrophyte biomass, evenness, and diversity across different experimental conditions and sites.
Main Results:
- Increased nutrients enhanced macrophyte biomass and evenness in low-consumer, low-nutrient-loading tide pools.
- Abundant consumers negatively impacted macrophyte diversity and biomass.
- Experimental reversal of conditions at a wave-protected site mimicked wave-exposed community structure.
- Structurally complex macrophyte functional groups increased in abundance and evenness.
Conclusions:
- Nutrient availability and consumer pressure are key drivers of coastal macrophyte community structure.
- Open-coast tide pools respond differently to nutrient enrichment than semienclosed systems.
- Climate change-induced shifts in nutrient regimes could significantly alter coastal macrophyte abundance and diversity.