Fraschetti S., Chimienti G., Cebrian E., Garrabou J. - University of Salento, University of Bari, CoNISMa, University of Girona and Institut de Ciències del Mar
Coastal areas are key areas for the economic development of our society. More than 60% of human population live near the coasts and a wide array of economic activities are developed there, such as tourism, fishing, transportation and power generation. There is a need to protect coastal marine habitats against degradation while developing economic activities in these populated areas.
A diverse array of environmental initiatives (e.g. EU Water Framework Directive, UNEP Barcelona Convention) are being implemented to reverse the current degradation trend and promote the sustainable use of marine ecosystems. However, the lack of ecological knowledge on the functioning and structure of coastal ecosystems presents a challenge: how can the recovery of degraded habitats be speeded up through marine ecosystem restoration measures?
The development of new efficient restoration protocols that can be scaled-up to large spatial scales may benefit the environment and generate economic revenues, such as from tourism. In this issue, we present two case studies on the restoration actions of key Mediterranean coastal habitats: coralligenous habitats and the macroalga Cystoseira.
Figure 1. Cystoseira on the shoreline. Photo credits to Simonetta Fraschetti.
Coralligenous habitats
There is an increasing recognition of the importance of cultural ecosystem services (CES) of marine habitats for supporting the management of marine systems. However, CES are still largely unknown compared to other ecosystem services (e.g. provisioning services) owing to the challenge of quantifying and valuing them. This is especially true when aesthetic, spiritual/cultural well-being and educational benefits are included in the assessments.
In the Mediterranean Sea, coralligenous bioconstructions are key coastal habitats because of their structural and functional importance. They exhibit high aesthetic value. Recently, a systematic mapping of the most visited diving sites across the Apulia region (Adriatic and Ionian Seas, Italy) has been carried out to understand the spatial distribution of coralligenous habitats and their ecological features. The habitats which scuba divers preferred to visit were assessed in order to quantify their economic contribution of local recreational activities. In addition, the proportion of CES that could be attributed to diving on coralligenous habitats were estimated recognising that scuba diving is closely related to cultural benefits (such as spiritual and aesthetic experiences).
Figure 2. Diving on a coralligenous reef. Photo credits to Alberto Liturri.
The results show that coralligenous habitats in this area of the Mediterranean Sea generate an economic contribution of 4.7 M euro/year. While these assessments probably underestimate the contribution of coralligenous formations, because not all ecosystem services provided by coralligenous habitats were valued, they highlight the magnitude of importance of this habitat and the recreational opportunities and tourism income they provide to local economies. The results emphasise the potential of including economic instruments in planning sustainable activities and setting priorities for conservation planning and coastal management decisions. The findings further stress that conservation is not sufficient alone and that concrete actions dedicated to the restoration of these valued habitats are critically needed.
Warning signs in the ecological health of the brown algae Cystoseira
The issue. Macroalgal forests such as kelps and fucoids are dominant habitat-forming species in rocky intertidal and subtidal habitats around all European coasts. They enhance coastal primary productivity and are recognized hot spots of diversity providing biogenic structure, food and habitat to diversified assemblages of understory species. In Mediterranean coastal areas species of the fucoid algae Cystoseira form dense canopies which maintain rich understory assemblages of sessile and vagile invertebrates and smaller-sized algae by providing shade and reducing physical stress due to aerial exposure. Two species – Cystoseira crinita and C. balearica – form underwater forests, which have a high nursery value: densities of several reef fish juveniles – particularly Symphodus spp. – have been found to be about 10 times greater in Cystoseira forests than in other habitats. The likely consequences of the alteration of this habitat are substantial with obvious consequences on the goods and services they provide.
The regression, and even disappearance, of macroalgae forest is occurring at large scale related to a variety of different stressors, such as pollution, coastal development and urbanization, outbreaks of grazer populations, species introductions and climate change. Besides global stressors, multiple local stressors, such as abandoned fishing gear (nets, trammel nets, threads) and trampling, threaten local and restricted macroalgae populations. The decline or disappearance of Cystoseira forests from many Mediterranean areas is leading to severe habitat transformations, with the loss of three-dimensional structures and associated biodiversity. It is surprising how little is known about most of these species and their population dynamics. The available literature suggest that the recovery of fucoid populations can take decades, probably due to their poor dispersal ability and the slow population dynamics. Clearly habitat conservation measures alone are not enough and systematic restoration actions are needed to reverse present losses.
For further information contact Simonetta Fraschetti (simona.fraschetti@unisalento.it), Department of Biological and Environmental Sciences and Technologies, University of Salento, CoNISMa; Giovanni Chimienti (giovanni.chimienti@uniba.it) Department of Biology University of Bari, CoNISMa; Emma Cebrian (emma.cebrian@udg.edu), Department of Environmental Sciences, University of Girona, and Joaquim Garrabou (garrabou@icm.csic.es), Institut de Ciències del Mar. Please also visit www.marineforest.com.
