Understanding seagrass resilience in temperate systems: the importance of timing of the disturbance. (July 2016)

• Record Type: Journal Article
• Authors: Soissons, Laura M.; Li, Baoquan; Han, Qiuying; van Katwijk, Marieke M.; Ysebaert, Tom; Herman, Peter M.J.; Bouma, Tjeerd J.
• Is Part Of: Ecological indicators. Volume 66(2016)
• Page Start: 190
• Page End: 198
• Publication Date: 2016-07
• Subjects: Indicators for ecosystem health -- Resilience -- Leaf Area Index -- Recovery -- Zostera marina -- Temperate systems -- Timing of disturbances; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2016.01.030
• Languages: English
• ISSNs: 1470-160X

Abstract

Highlights: Seagrass resilience and indicators are tested along their growing season. Recovery is higher at the start of growth and declines when cover increases. The response of indicators of resilience depends on the timing of the disturbance. Timing of the disturbance is crucial for the evaluation of seagrass resilience. Abstract: Temperate seagrass meadows form valuable ecosystems in coastal environments and present a distinct seasonal growth. They are threatened by an increasing amount of stressors, potentially affecting their capacity to recover from disturbances. We hypothesized that their resilience to disturbances is affected by seasonal dynamics. Hence, we investigated the effect of the timing of the disturbance on seagrass Leaf Area Index (as a proxy for presence, or 'visible' status), recovery from disturbance (as a proxy for meadow resilience), and rhizome carbohydrates (as a proxy for longer term resilience) by a series of four disturbance-recovery field experiments spread over the growing season at two sites in Shandong Province, China. During the course of the growing season, we found the highest recovery at the start of the growing season, lowest recovery when Leaf Area Index peaked around mid-growing season, and intermediate recovery when Leaf Area Index decreased at the end of the growing season. Rhizome carbohydrates were not affected by disturbances during any of the four experimental periods and could not explain the low recovery during mid-growing season. The two sites differed in exposure and in the occurrence of incidents like a green tide and storms, which affected recovery. However, general patterns were similar; timing strongly influenced the indicator of meadow resilience and its correlation with presence during the two main seagrass growth phases. Our results emphasize the importance of carefully considering timing in the evaluation of seagrass resilience in temperate systems. Furthermore, our study implies that, to effectively protect seagrass beds, conservation management should aim at avoiding disturbances particularly during the peak of the growing season, when resilience is lowest.