TitleRe-oligotrophication trajectories of macrophyte assemblages in Mediterranean coastal lagoons based on 17-year time-series
Publication TypeJournal Article
Year of Publication2019
AuthorsLe Fur, I, De Wit, R, Plus, M, Oheix, J, Derolez, V, Simier, M, Malet, N, Ouisse, V
JournalMarine Ecology Progress Series
Volume608
Pagination13 - 32
Date Published01/2019
ISSN0171-8630
Keywordsparker solar probe; Solar Probe Plus; Submerged aquatic vegetation · Recovery · Nutrient reduction · Restoration · Long-term data series · Resilience · Regime shift · Coastal lagoon
Abstract

ABSTRACT: Since the mid-20th century, Mediterranean lagoons have been affected by eutrophication, leading to significant changes in primary producers. In the early 2000s, management actions have been implemented to reduce nutrient inputs with the aim to achieve a good ecological status as requested by the EU water framework directive. As a result of these actions, a sharp decline in nutrient loads has been recorded in several lagoons leading to an oligotrophication of the water column. The analyses of a long-term data set (1998-2015) of 21 polyhaline and euhaline lagoons with contrasting trophic status allowed us to infer a general scheme for the changes in macrophyte assemblages during the oligotrophication process. Placing hypertrophic and oligotrophic conditions end to end, we inferred that the general pattern for the re-oligotrophication trajectory in Mediterranean coastal lagoons is described by the following sequence, with regime shifts between each state: (1) bare non-vegetated sediments, phytoplankton-dominated state; (2) opportunistic macroalgae; (3) seagrass and perennial macroalgae dominated state. However, we did not observe the latter regime shift for the most eutrophicated lagoons, which, so far, remained stuck in the opportunistic macroalgae state. So far, the shift from dominance of opportunistic macroalgae to a system dominated by seagrasses was only observed in a single lagoon where seagrasses had never completely disappeared, which possibly relates to resilience. More generally, the conditions favoring regime shifts from opportunistic macroalgae to seagrasses are still poorly understood. In conclusion, we describe a generic pattern for re-oligotrophication of Mediterranean coastal lagoons, although a full recovery from highly eutrophied to oligotrophic conditions may require more than a decade and may include conditions that remain so far poorly recognized.

URLhttps://www.int-res.com/abstracts/meps/v608/p13-32/https://www.int-res.com/articles/meps_oa/m608p013.pdf
DOI10.3354/meps12814
Short TitleMar. Ecol. Prog. Ser.


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