Environmental Sensitivity classification of the coasts of Balearic Islands is based on the international standard proposed by NOAA (2002) designed for the establishment of the Environmental Sensitivity Index (ESI). The adoption of this method proposed by NOAA responds to the need for standardization in terms of the response to pollution and the location of sensitive resources that may be affected. According to these guidelines and the main characteristics of the coastal resources and type of information in Balearic Islands, Environmental Sensitivity Maps (ESM) comprises three types of information:
1.- Shoreline classification (download shoreline classification)
Shoreline classification (Coastal Habitats: NOAA, 2002) (Figure 1), is the strongest task of the work presented. Coastal habitats are at risk of contamination during an event of marine oil spill whose effects can vary significantly depending on the type of coast. In the Balearic Islands its have been applied the classification criteria proposed by NOAA (2002) to the types of local coasts. The classification of the coastline (Figure 1) has been based on:
The height criteria for the coasts have been determined according to first scientific works related to coastal geomorphology of the Balearic Islands (Butzer, 1962; Rosselló, 1964, 1975; Servera, 2004) which establish 3 meters height as the boundary between high and low coasts. The height criteria was also adopted for further studies (Balaguer, 2005) which also were used to establish the sensitivity of the shoreline. Coastal height will determine the accessibility of cleaning staff to the coastline for cleanup and restoration tasks during an oil spill.
According with the exposure degree to wave energy exists two different main types of coasts (NOAA, 2002): a) coasts exposed to waves or high energy coasts corresponding to those coasts affected by the direct impact of waves and therefore, the hydrocarbons will tend to be naturally removed, and b) sheltered coasts, located in low energy environments where the wave is not an important shore modeler. In these type of coasts, hydrocarbons will tend to be slowly removed naturally and therefore self-restoration will be slow.
Exposure degree to wave is determined: 1) articulation degree of the coastline (capes, bays, inlets, natural harbors, etc.), and 2) the characteristics of the seabed in the coastal area conditioning the dissipation of wave energy allowing or not arrival of wave trains resulting to direct impact or reflection processes.
Substrate type determines the penetration of oil inside the materials that constitute the shoreline. The most important distinction is between bedrock and unconsolidadted sediments (NOAA, 2002). The penetration depth is controlled by the grain size of the substrate and its classification into the substrate that will condition the persistence of oil inside the substrate and will lead long-term biological impacts. Normally, the deepest penetrations occur in sediments from gravel size (> 2mm).
Man-made ripraps are types of coasts that have a high secondary porosity (large space between boulders) allowing deeply penetrate of hydrocarbons and act as storage areas for extended periods of time.
Finally, coastal areas associated with lagoons and marshes, have low accessibility due to high proportions of silt and clay, so that the foot traffic and use of machinery is not possible because would generate irreversible damage both in the biotic environment and structure of the physical environment and would enhance the penetration of hydrocarbons inside the substrate.
Biological sensitivity degree as a component of geomorphological features of coasts it refers to ability of the coastal environment to host different types of habitats.
The different types of coasts depend on the main morphostructutral characteristics of the coastal area (regional context) in which they develop. Different coastal environments or coastal habitats are not hermetically relative to one another, they develop gradually according to the physical conditions which constitute the coasts (substrate type, wave exposure degree, prevailing weather conditions).
It is necessary to note that salt or brackish water lagoons and marshes close to shoreline, in some cases, do not have a direct connection with the nearshore zone but nevertheless, the waterfront is considered as a high vulnerability shoreline due to biological richness and fragility of their natural communities. Other coasts, such as exposed vertical cliffs (1-A, Figure 1) where do not develop a transcendence habitats either physical, chemical, or have environmental as lagoons and marshes, have a greater resilience and require less time for self-restoration.
Figure 1: Classification of coasts of the Balearic Islands according with its Environmental Sensitivity adapted from the standard established by NOAA (2002). The legend has been changed from 9 types of coastline (17 subtypes) to 8 (15 subtypes).
In the figure we can see the coastal types affected by changes in the legend. Beach coasts located in sheltered environments (8-A and 8-B) have been included in the types of coasts relating to sand and gravel beaches (3-A and 6 - A, respectively). According to the revision of the NOAA guidelines (2002), restoration and clean up activities in beach coasts are affordable tasks because the characteristics of the substrate can support vehicular and foot traffic, and also distribution of buried fauna varies significantly both spatially and temporally, and most cases are independent of the degree of wave exposure. Its important to note that digital maps of shoreline Environmental Sensitivity of the Balearic Islands (GIS environment) keep the modified information (type of coasts) in the attribute tables indicating whether a beach coastline has been considered previously as 8-A and 8-B.
Biological and/or ecological characterization is based on the development of different degrees of biological vulnerability of the coasts of the Balearic Islands. Biological vulnerability degrees have been made according to the number of protection figures (marine and terrestrial) located at coastal areas according with Coastal Sensitivity Atlas of Finisterre Region elaborated by the CEDRE (Centre de Documentation et Recherche sur les pollutions dÉxperimentations et des Accidentelles des Eaux) in collaboration with POLMAR (Pollution des Mers), IUEM (Institut Universitaire Européen de la Mer) and IFREMER (Institut de Recherche Française pour l'Exploitation de la Mer) (Pombo, 2005).
The establishment of the biological / ecological sensitivity level in the Balearic Islands it has been considered different types of protection comprising international, european, national and regional levels. Types and levels of environmental protection considered are listed below:
1) International level:
2) European level:
- Special Protection Areas (SPAs) (Nature Network 2000. Birds)
- Special Areas of Conservation (SACs) (Nature Network 2000. Habitats)
3) National and Regional level:
- Natural Area of Special Interest (ANEI) (included Quercus ilex protection)
- Protection of Coastal Area (APT-Costa) (figures from PTIs)
- Natural Areas of High Level of Protection (AANP) (figures from PTIs)
Declaration of protection figures are due to the characteristics of the natural environment, understood as a set composed by biological, geomorphological and socio-cultural factors, at insular, national and / or regional level. According to above mentioned, biological and ecological elements in each protected areas have a great weight, enough to give them a significant vulnerability. For more detailed information see the evolution of protected areas of Mallorca-Cabrera and Menorca (section of indicators and data of SIAS Division of SOCIB).
Human-use resources applied to shoreline environmental sensitivity are based on the identification and location of points/areas of interest in case of an oil spill. Features considered are infrastructures, equipments, services, leisure activities (eg water sports) and historical-cultural areas (archaeological) that have to be taken into account in case of oil spill because: 1) these points/areas could receive the direct impact of an oil spill, 2) some of these areas can be damaged during cleanup task, or 3) some of these infrastructures, equipments and services may be helpful in the cleanup and restoration of the shoreline.