Chronically elevated sea surface temperatures revealed high susceptibility of the eelgrass Zostera marina to winter and spring warming

Yvonne Sawall*, Maysa Ito, Christian Pansch

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
9 Downloads (Pure)

Abstract

While it is well known that severe marine summer heatwaves can cause acute and dramatic die-offs of seagrass meadows, the effect of trans-seasonal warming and winter/spring heatwaves are yet poorly understood. This study simulated a 9-months warming scenario on the common seagrass Zostera marina from winter into summer, using outdoor mesocosms, which provided near-natural conditions. The relevance of the natural temperature pattern, as well as the 3.6°C warming, and their implications were further discussed in the context of a 22-yr temperature time series of the study region. Survival of plants was high in winter independent of temperature. In spring, however, heat-treated Z. marina flowered 1.5 months earlier and experienced high mortalities. Thereafter, plant survival, growth, and pigmentation were largely comparable between temperature regimes. Yet, a comparatively high mortality occurred in ambient plants, after an abnormally warm June. Final biomass was reduced by ~ 50% in heat-treated plants. These results imply that warm winter-to-spring conditions can have severe effects on vital seagrass traits. Warming accelerates consumption of energy reserves triggering advanced flowering, similar to many terrestrial plants. Although, surviving heat-treated plants were not able to re-stock energy reserves throughout the high-light summer as inferred from low plant biomass, these seemed rather resistant to summer heatwave events.

Original languageEnglish
Pages (from-to)4112-4124
Number of pages13
JournalLimnology and Oceanography
Volume66
Issue number12
DOIs
Publication statusPublished - Dec 2021
MoE publication typeA1 Journal article-refereed

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