Inter-Research > MEPS > v637 > p45-57  
MEPS
Marine Ecology Progress Series

via Mailchimp

MEPS 637:45-57 (2020)  -  DOI: https://doi.org/10.3354/meps13231

Impacts of the non-native alga Sargassum horneri on benthic community production in a California kelp forest

Genoa H. Sullaway1,2,*, Matthew S. Edwards1

1Coastal and Marine Institute Laboratory, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA
2Present address: NOAA, Northwest Fishery Science Center, 2725 Montlake Blvd E, Seattle, WA 98112, USA
*Corresponding author:

ABSTRACT: The arrival of Sargassum horneri throughout the Southern California Bight and the Baja Peninsula has raised concern regarding kelp forest resilience and ecosystem function following the invasion of this non-native species. To understand how S. horneri impacts native algal abundance and community production, we removed S. horneri from experimental plots over a period of 11 mo. We measured impacts on native algal communities and community productivity using SCUBA surveys and benthic chambers equipped with oxygen, temperature, and light sensors. We observed a nearly 4-fold increase in recruitment of Macrocystis pyrifera and a 9-fold increase in adult M. pyrifera stipe density in S. horneri removal plots, but no discernable changes in net community production among treatments. We found ephemeral increases in gross community production and community respiration in the non-removal plots that coincided with periods of peak S. horneri biomass. To understand the temporal dynamics of community production, we deployed benthic chambers across a rocky reef dominated by S. horneri. Here, temporal variation in community production was most strongly related to corresponding variation in water temperature and changes in S. horneri biomass related to its annual lifecycle. Overall, our study indicates that S. horneri presence contributed to ephemeral increases in gross community production and community respiration, but it did not affect net community production. Moreover, S. horneri removal can lead to increases in native algal abundances given favorable abiotic conditions. We suggest that S. horneri thrives in a disturbed ecosystem rather than being a driver of ecosystem change.


KEY WORDS: Kelp forest · Non-native algae · Community production · Community respiration · Sargassum horneri


Full text in pdf format 
Cite this article as: Sullaway GH, Edwards MS (2020) Impacts of the non-native alga Sargassum horneri on benthic community production in a California kelp forest. Mar Ecol Prog Ser 637:45-57. https://doi.org/10.3354/meps13231

Export citation
Mail this link - Contents Mailing Lists - RSS
Facebook - - linkedIn