In order to illustrate the future evolution of the threat to Posidonia, we might decide to track coverage of the habitat as our variable, using aerial photography or satellite imagery. We might even settle for a second monitored variable, in this case the health and growth status of the Posidonia meadows seems a good choice. The latter would involve in situ sampling of the meadows by divers with subsequent analysis of shoot densities and the level of necrosis that is evident.
Characteristics such as those mentioned above, that is, coverage, shoot density, and level of necrosis, represent the 'hard' or 'measureable' elements of this system dynamic. Other hard elements we may take into account include the quality of the water surrounding the Posidonia meadows or the number of aquaculture farms or sewage outflows in a given area. The level of nearby dredging and/or trawling activity may prove a greater challenge to quantify as do the actions of boat owners in mooring/anchoring their vessels.
'Soft'elements in the system include legislation protecting this seagrass species and the shortcomings of these protective policies. Public awareness of ecological services that Posidonia oceanica offers may serve to modify the existing pressure on this protected habitat. The way in which this species is and shall respond to climate change is another ambiguous factor that is not easily determined.
While I am certain that the above painted picture is not complete, I leave the rest to your comments for now. What do you see?
Sea grass...what would the oceans and seas be without it? I can't even imagine. As a marine biologist, I have spent many hours in sea grass beds - studying transects, counting and IDing fish and invertebrates, counting shoots, etc. I had no idea that such an integral part of the marine ecosystem was in peril. That is problem number one - lack of awareness/education. Now, in my studies in the States, there was always bias toward the Atlantic Ocean due to the location of my University. Still, I should have been aware. Lack of awareness, I believe, would have and still does contribute to P. oceanica's decline.
ReplyDeleteThese days we also cannot forget the effects of climate change. Has the water temperature changed at all? Has salinity levels changed? What about the acidity of the water? Have new organisms inhabited the sea grass beds due to changing water temperatures, and now use P. oceanica as a food source? In such a dynamic ecosystem as the sea, I feel like there in an infinity of elements...systems thinking definitely helps us get those ideas "on the table."