Ietto, F.; Pellicone, G.; Cantasano, N. Silting Process and Loss of Posidonia oceanica Meadows in the Tyrrhenian Waters of Calabria (Southern Italy). Sustainability2023, 15, 13102.
Ietto, F.; Pellicone, G.; Cantasano, N. Silting Process and Loss of Posidonia oceanica Meadows in the Tyrrhenian Waters of Calabria (Southern Italy). Sustainability 2023, 15, 13102.
Ietto, F.; Pellicone, G.; Cantasano, N. Silting Process and Loss of Posidonia oceanica Meadows in the Tyrrhenian Waters of Calabria (Southern Italy). Sustainability2023, 15, 13102.
Ietto, F.; Pellicone, G.; Cantasano, N. Silting Process and Loss of Posidonia oceanica Meadows in the Tyrrhenian Waters of Calabria (Southern Italy). Sustainability 2023, 15, 13102.
Abstract
In the Mediterranean Sea, there are two critical issues affecting marine benthic biocenosis: the sedimentation process and the increasing trend in marine biodiversity loss. These processes are very marked along the western side of Calabria coastline where siltation is one of the main reasons for the regression of Posidonia beds in the regional coastal waters. This research aims to investigate the relationships between the geomorphological features of the debris source areas, represented by fluvial basins, and the distribution of Posidonia meadows. So, a geomorphological study of the Tyrrhenian fluvial basins with area greater than 200 km2 and its correlation with the mapping of the meadows in the Calabria Tyrrhenian waters was carried out. Furthermore, in order to assess the increased level of burial in a Posidonia oceanica meadow and its health state over time, a program of Posidonia monitoring was undertaken between 2000 and 2010, in a test area located in the Marine Regional Park of Isca (Calabria, Southern Italy). The results of this survey highlighted that, at the beginning of the study period, for a silting rate of 4 - 5 cm/year, the meadow suffered a reduction of its photosynthetic ratio with a rate of mortality of 50%. In the following years, the siltation rate reach 12 cm/year in 2010 and the meadow began to disappear. Therefore, the marine pollution by sedimentation represents a serious factor for the regression of Posidonia oceanica meadows, enhancing the risk of a gradual loss in marine biodiversity.
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received:
31 May 2023
The commenter has declared there is no conflict of interests.
Comment:
I am sure that authors wished to report as the adverse conditions for sure threaten the Calabria coast to suggest in which direction the conservation strategies have to be addressed. Even if the work presents novelties in the approach, in particular for the case study, the authors report results that are 20 years old. What happened in the meantime? Is there still Posidonia? The authors stated to have monitored the site by the citizen science, but no details on survey methods or related results have been reported. The direct monitoring techniques of the meadow are not well described and documented, the statistics are not reported to evaluate the significance of the data. There is only one regression curve of mortality index, that it is not enough to describe the trend. The solely data that should be useful to demonstrate the regression are the percentage of the plant coverage and the regression of the upper and lower limits of the meadow. To demonstrate the regression of the meadow, the authors rely on two photographs of the site at 10 year distances each other. I think it is not scientifically useful. Plant density alone do not demonstrate meadow regression, but classification into ecological status classes (Giraud, Pergent indices). Another aspect, in the abstract the authors report that regression of Posidonia was caused by the reduction of its photosynthetic ratio, but neither techniques nor results on the measurement of photosynthesis are reported. Indeed, there is no doubt that many factors contribute to the regression, as demonstrated by the huge literature on the subject, including photosynthetic deficiency is one of these.My advice is to interact with ecologists or marine biologists who usually monitor Posidonia. I hope that the revision process should return a manuscript which will be sound in science
The commenter has declared there is no conflict of interests.