A New Vanishing Act: P. oceanica

The issue of concern in this study is the significant and widespread decline of the Mediterranean seagrass, Posidonia oceanica (L.) Delile, in the Mediterranean basin. This species belongs to the flowering plant group Angiospermae, the superior plants, and forms a habitat type, Posidonia meadows or beds, the functions of which are vital to the health of many ecosystems. The importance of Posidonia oceanica is widely recognized, in serving as a nursery ground for many fish and invertebrates (a larval anemone grows on P. oceanica's leaves in the picture on the right), protecting the coastline from erosive forces and in its release of volumes of oxygen to the sea – Posidonia oceanica has often been described as ‘the lungs of the Mediterranean’. 

Although recognized as a priority habitat for conservation in the EU, it is estimated that the Mediterranean’s Posidonia oceanica beds, which are spread over some 50, 000 km² of the seabed, are disappearing at an annual rate of 5%. 

P. oceanica is a protected species under the Bern Convention while Posidonia meadows are listed as a priority habitat in Annex 1 of the EU Habitats Directive implying a consequent high level of protection through designation of areas of special conservation. International protection for P. oceanica is also specified under the Barcelona Convention and the species/habitat additionally receives specific legal protection in several European countries. Although Posidonia oceanica is not legally protected in Maltese waters, Malta bears obligations to protection of the species/habitat as a signatory of the Bern and Barcelona Conventions, and as a member of the European community. 

Despite the above mentioned conservation laws and agreements, failure to provide adequate protection for Posidonia meadows is prevalent - the violation of both national and international law has been unmistakeable to this effect. This evident lack of conservation action and policy implementation is of undoubtedly great consequence with respect to loss of P. oceanica habitat.

The purpose of this study is to identify the dynamics that play a role in determining P. oceanica's decline and possibly identify suitable scenarios under which this trend could be reversed.

In the mood for chocolate

To all of those non-chocaholics out there, the curse of being totally addicted to chocolate is that one is restricted to consuming either A LOT of chocolate, or nothing at all.  No real chocaholic would be able to stand the torture of consuming one small piece of chocolate every day.  Addicts like myself are doomed to yo-yoing between the two loops below.  

The situation starts when you realise 'Oh, it's time I lost some weight!' Being perfectly aware of the calorie load that can be chopped off simply by abstaining from chocolate, you decide 'OK! No more chocolate, starting TOMORROW!' (one always embarks on such a difficult quest tomorrow, and never at the instant at which one commits to the decision) .  So far so good.. cutting out your main calorie source, you begin to lose weight and feel happier about yourself.  This is the balancing feedback loop, no pain no gain - there never was a truer phrase.  Yes, no chocolate is one of the worst kinds of pain for the chocaholic.  

There's just one problem - after a while you begin to wonder about how chocolate tasted back when you used to eat it.  You drool at the sight of anyone eating a chocolate bar, you begin to find difficulty in restraining yourself every time you open the fridge, or every time you pass in front of a shop packed with chocolate goodies.   If that wasn't enough, you KNOW you've been truly defeated when you begin to dream about eating chocolate in your sleep! You wake up the next day and the FIRST thing you do is march right out the house and come back with 4 bars of chocolate.  You find a dark corner inside your house, curl up and munch away with glee.  You are reacquainted with the joy that is chocolate, and now you find it hard to stop.  Your weight goes up again and you are back to where you started.  This is the reinforcing loop titled 'chocolate love affair', and as with all love affairs, one that is very hard to stop..  once you are stuck in this loop it is often a while before you gain enough weight to signal 'stop eating chocolate' again.  

It is obvious that cutting out chocolate from one's diet is not the answer to losing weight.  This is the inadequacy of the approach in this example.  I suppose that putting in an exercise loop somewhere in the causal loop diagram below would serve to balance out the unintended consequences that accompany complete abstinence from chocolate.  Other variables I know contribute to this problem are lack of time in which to exercise as well as the pressure of other duties such as school or work that keep one stuck at a desk - chocolate is a cheerful sight to the overworked student.  

I have kept the diagram simple as requested, however I really think there is potential for it to expand further.  All this talk about chocolate has got me wondering.. surely one little piece won't hurt.. or would it?!

Posidonia oceanica: a systems dynamic approach

Now that I've introduced you to this special sea grass, it is time to start getting busy with some serious systems elements for our systems approach to this important problem!  Data on how the Posidonia oceanica habitat has evolved over a long period of time is not very abundant.  Recent studies and data do show however that this seagrass is one of the oldest inhabitants of the Mediterranean basin and is currently on the decline, and at an alarming rate at that!

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?

Meet Posidonia oceanica

Hello there! May I introduce you to Posidonia? And all the guys are thinking "hell yeah you can!" Posidonia's surname is oceanica, and its really a genus name rather than a surname.. yes you've guessed by now! Posidonia oceanica is not a person but a plant, a flowering plant in fact, that makes its home in the Mediterranean sea.

Posidonia oceanica is already your friend, only you probably don't even know it.  Posidonia provides shelter and breeding grounds for many of the delicious fish, bivalves, cephalopods, and crustaceans that so often find their way onto your dinner plate.  Your leisure is provided for when Posidonia attenuates currents and waves that would otherwise erode away the beach on which you may choose to sunbathe in summer or stroll along during the winter.  Posidonia oceanica breathes life into the underwater world by releasing large volumes of oxygen, supporting all kinds of existence both in the sea and, indirectly, on land.

As one of the receivers of all of these benefits, you may want to be aware of the current threats to Posidonia's wellbeing.  Members of your same species, Homo sapiens, are jeopardising Posidonia's home by spilling chemicals and excess nutrients into the sea, discharging brine from desalination plants, introducing invasive species, dredging and trawling.  Posidonia oceanica's address has always been 'No 1, "All Over", The Mediterranean Sea'; there really is no other place for her to seek shelter until the danger is over.  It is far time we started to appreciate the many advantages of our relationship with Posidonia.  Where would we be without her I hear you ask? Who knows, lets not wait to find out!!

Post number one

Ok here goes! its been so long since I last had a blog.. lets see..

Self description

• mother of Jack, a mischievous four year old;
  
• curious, interested in just about anything and everything;
  
• passionate about playing football, other sports and outdoor activities.
  
• additional details are to be further disclosed..

Thoughts on the SERM program

• so far so good!
• enjoying the different methods of teaching and assessment
• highly interesting

After the program

• no concrete plans, money, fun and a PhD would'nt hurt though :S