State of the Med: the UNEP 2009 report

The UN Environment Programme (UNEP) Mediterranean Action Plan (MAP) and its Regional Activity Centres have released the first State of the Environment and Development report covering the Mediterranean region, which tackles key environmental issues, including climate change. The “State of the Environment and Development in the Mediterranean 2009″ was released during the 16th Meeting of the Contracting Parties to the Barcelona Convention, which took place from 3-5 November 2009, in Marrakech, Morocco.

The report is a pilot exercise, based on available sources of information and covers the 21 countries bordering the Mediterranean Sea. It finds that climate change is already occurring in the region and forecasts that it will lead to, inter alia, a decline in rainfall, increased periods of droughts and rises in sea-level. The report also identifies the most vulnerable Mediterranean zones and states that climate change will also affect agriculture and fishing, the attractiveness of tourism, coastal zones and infrastructure, and public health.

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The Report

Watch out: jellyfish!

Jellyfish blooms were rare episodes in the Mediterranean until the last eight years, when massive swarms of gelatinous organisms have become a frequent sight in coastal waters. Although overfishing and climate warming are amongst the most probable drivers, the specific causes and mechanisms are not well identified, and the lack of reference data makes any further investigation difficult.

The new CIESM Jelly Watch Programme shall gather for the first time baseline data on the frequency and extent of jellyfish outbreaks across the Mediterranean Sea.

Coastal users (fishermen, divers, tourists) but also ferry passengers, are invited to report sightings of jellyfish swarms (see poster for species) with information on the location, type and extension of the observed swarms. Records are sentkey scientists who act as focal points in different regions. After accurate screening and validation of the records, data will be centralized and integrated in the CIESM Metabase.

National JellyWatch Focal Points:
Croatia - Adam Benovic, University of Zagreb
Israel - Bella Galil, IOLR
Italy - Ferdinando Boero, Univ. del Salento: boero[at]unile.it

For more information:

CIESM Jellywatch Program website

Boero et al. 2008 "Gelatinous plankton: irregularities rule the world (sometimes)" Mar Ecol Prog Ser 356: 299–310.

Rocky deserts at sea: causes and solutions

Many vegetated systems in temperate regions throughout the world may face dramatic ecosystems shifts to unvegetated states. So, flourishing kelp forests may become desolated bare rocky substrates void of the rich floras and faunas usually associated to forests.

In the Mediterranean there are no kelp forests, but rocky bottoms can be covered by macroalgae (e.g. Cystoseira spp) that host juvenile and adult stages of many invertebrate and fish species. The persistence of these macroalgal beds, that greatly contribute to maintain coastal biodiversity and productivity, is the result of a delicate equilibrium among environmental conditions, interactions among species and human disturbance.

In recent years it has been demonstrated that in Mediterranean rocky reefs where fishing is particularly intense fish predators may decrease in abundance and size. Their decreased predation impact on preys, including sea urchins (the most important grazers in such systems), may reflect in a dramatic increase of prey abundance.

The ultimate consequence of the fishing impact may thus be an increased grazing impact of sea urchins that causes the transition from macroalgal beds to the so-called ‘barrens’, that is bare rocks partially covered by encrusting coralline algae. They are a sort of rocky deserts.

How to cope with this? Management of complex natural systems is not easy because many processes may interact. Formation of barrens, for instance, can be also a consequence of other processes like water warming or sedimentation. However, fishing restrictions and fish predator recovery may be useful to reverse this phenomenon.

From this perspective, there is increasing evidence that the creation of effective Marine Protected Areas (and not paper parks) can allow fish predators to recover along with their potential in controlling sea urchin populations and their effects on macroalgae.

At the MPA of Torre Guaceto (SE Italy), in the same rocky reefs where in the past (before the establishment of the MPA) there were barrens, there are at present (after about 7-8 years of effective protection) more fish predators, less sea urchins and lower barren covers than outside the MPA, which is the proof that properly managed MPAs can allow the entire ecosystems to recover.

Paolo Guidetti

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For more information:
Guidetti P. 2006. Marine reserves reestablish lost predatory interactions and cause community changes in rocky reefs. Ecological Applications 16(3):963–976.

How climate influences the deep sea

Picture the Grand Canyon in Arizona - then place it under the sea: the Mediterranean seafloor is criss-crossed with deep submarine canyons that in sheer size put their land counterpart to shame. Rivers of dense waters flow through these canyons, their capacity varying depending on climate-induced phonomena.

During such an event, the amount of water transported in 4 months from the Gulf of Lion to the deep Western Mediterranean via the Cap de Creus canyon equalled 2 years of input from all rivers draining in the Mediterranean.

How these dense shelf water cascading in the Gulf de Lion affect the population of the deep sea shrimp Aristeus antennatus, the most valuable deep-sea living resource in the Mediterranean Sea, was recently discovered by Spanish researchers. Initially, the strong currents (up to 80 cm/sec) displace shrimp populations from the normal fishing grounds, producing a temporary fishing collapse. However, the food provided by the currents soon leads to a large increase in recruitment - which results in plentiful landings of large shrimps 3-5 years after major cascading events.

These new findings resolve the paradox of a long-overexploited fishery that has not collapsed after 70 years of intense deep-sea trawling. But climate change is expected to cause a decrease of winter deep water formation in the Gulf de Lion, which in turn could decrease the frequency and intensity of dense shelf water cascading events. Without this regenerative mechanism, fishery pressure could quickly deplete the stock of Aristeus antennatus and other valuable deep-sea living resources in the area.

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For more information:
Company et al (2008) Climate influence on deep sea populations. PLoS ONE 3(1): e1431.
Eureka alert press release (Jan 15th 2008)

What is Mediterranean Conservation?

Mediterranean Conservation explores the possibility of merging the communication efforts of individuals committed to marine conservation in the ancient Tethys Ocean.