Coastal development has an undeniable impact on marine ecosystems resulting in the detriment of the more sensible communities. Posidonia oceanica meadows are climax communities which offer a wide variety of ecosystem services both ecological and socio-economic. Human-derived impact on these habitats has been widely assessed although conclusions may vary depending on the area.

This study analyzed the long-term (1984-2014) P. oceanica meadow regression next to the city of Alicante (SE Spain) using bionomic cartographies and sides-scan sonar images.

The obtained results showed a 25% colonized area reduction since 1984, this progress being more rapid during the 1984-1994 period and decreasing with time. Cover and density have suffered a significant decrease in the last 20 years, mainly in the upper limit of the meadow.

The authors highlight that there are several coastal impacts which have co-occurred in the area in the last few decades (port enlargement, brine and sewage discharges, industrial activity) thus resulting in the regression of the meadow. It is concluded that the existing negative trend of the measured descriptors indicates the necessity of implementing management actions which focus on the present sources of impact and actively reduce their effect on P. oceanica beds.

https://www.sciencedirect.com/science/article/abs/pii/S0141113622000022

Blanco-Murillo et al. (2022) Posidonia oceanica L. (Delile) meadows regression: long-term affection may be induced by multiple impacts. Marine Environmental Research 174: 105557.