LevelPressureOverall

LevelPressureNLoad

LevelPressureNConcentration

LevelPressurePLoad

LevelPressurePConcentration

LevelPressureOLoad

LevelPressureOConcentration

ImpactPressureWaterColumn

ImpactPressureSeabedHabitats

LitRock

ShallRock, ShallCoarseSed, ShallSand, ShallMud, ShallMxdSed

The main land-based sources of nutrients and organic matter in Maltese marine waters include sewage infrastructural discharges, sewage overflows and agriculture. Since 2011 all waste water discharged to the marine environment is treated, significantly reducing the nutrient load contribution from waste water discharge. Sewage overflows, which occur mainly during heavy rainfall events, are generally localized and of short duration. Nutrient input from agricultural sources into the marine environment is mainly related to diffuse pollution from run-off which contributes to the occasional nutrient enrichment incidences of sheltered inlets and bays around the islands. Due to the diffuse nature of this source, it is very difficult to quantify the contribution of this source from agricultural activity. A rough approximation of agricultural Nitrogen contribution discharged to the environment amounted to 163.7 tonnes during the first nitrate reporting cycle period (i.e. 2004-2007). Sea-based sources are mainly from offshore fish farms and marine traffic generated waste directly discharged to sea. With respect to aquaculture, there are 9 off-shore aquaculture sites in Malta. Most sites are located in open, exposed waters whilst the more sheltered sites are utilized for nursery production or broodstock holding. Tuna penning cages have to be sited at least 1km offshore in exposed waters that have strong currents and away from benthic habitats that are of ecological significance. The contribution of maritime traffic to nutrient enrichment still needs to be assessed.

• AgricultForestry
• Aquaculture
• Urban

The major difficulty encountered for the application of the available data on nutrient enrichment for the purposes of the MSFD assessment of status is related to the relatively recent implementation of the WFD monitoring programme hence the lack of long term trend data. Furthermore, there is very little data in relation to the some of the direct and indirect effects of nutrient enrichment as addressed by the MSFD criteria and indicators. Data on organic matter is also very limited. To date national nutrient standards have not been set for any of the nutrient parameters making up Malta’s monitoring programme. It is expected the WFD and Nitrates Directive monitoring would continue to improve our understanding of the extent of eutrophication risk to Malta's marine waters. In the future work carried out under these directives will be complemented by the long term ecosystems approach in assessing eutrophication phenomena, as advocated by both MEDPOL (Phase IV) and the MSFD working groups. This would result in a need for Malta to adopt a more precise means of assessing different degrees of nutrient enrichment and eutrophication. It would also enable the determination of the extent of impact on the different components making up the wider marine environment.