Lost and found: A new hope for the seagrass Cymodocea nodosa in the marine ecosystem of a subtropical Atlantic Island

Seagrass meadows are globally recognized as important coastal habitats due to the various ecological functions and ecosystem services they provide. Substantial global decline of seagrass habitats has been recorded over the last decades, underlining the need for extensive studies, including monitoring and mapping these habitats across their distributional range. Cymodocea nodosa (Ucria) Ascherson is the only seagrass species reported in the archipelago of Madeira (NE Atlantic) and systematic or reliable information of its occurrence is very scarce and mostly anecdotal. This study reports the discovery of a yearly-persistent patch of C. nodosa in the southeast coast of Madeira and provides insights into key ecological and biological aspects (e.g. density, leaf length, associated fauna and flora). Seasonal monitoring surveys over a 3-year period, indicate that (1) the patch has increased in size and shoot density over the study period, and (2) leaf lengths follow a typical seasonal pattern over the year. Accounts of past destruction of seagrass meadows in the island, underline the importance of continuous monitoring of the patch and adjacent areas to reveal how the current seagrass patch develops (i.e. patch continuity and/or disappearance), if it integrates a larger meadow and whether anthropogenic pressures as coastal development and/or associated terrigenous sediment runoff events will affect its resilience. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

Seagrass meadows are important coastal habitats globally, but are facing significant declines. A persistent patch of C. nodosa was discovered in Madeira, showing increases in size and density over three years, with leaf lengths following a seasonal pattern. Continuous monitoring of the patch and adjacent areas is crucial to understand its development.