Introduction

A series of hypersaline lagoons occur along the coastline of Rio de Janeiro, Brazil, in the area known as Região dos Lagos. They differ from each other in size, physicochemical, sedimentological, and biological characteristics. Rare examples of microbialites are found living in this lagoon system (Vasconcelos et al. 2006). An example of such a living microbial structure are stromatolites, which represent modern evidence of a sedimentological structure that is considered to be an indicator of the earliest life on Earth. The remarkable occurrence of stromatolites in this region is of great scientific interest because it enables the study of possible analogues for the Earth’s earliest life. Furthermore, this region contains many important geosites related to its unique geological evolution involving more than 2 billion years of geological history (Mansur et al. 2012). Unfortunately, the region has experienced an intense human activity and degradation in recent years.

Sustainability promotes environmental protection and social and economic development as interdependent and mutually reinforcing pillars of sustainable development (WSSD 2002). Action programmes should be implemented to cover a variety of themes, such as geoconservation, biodiversity, environmental pollution, urbanisation, freshwater supply, rural development, climate change, and others (Wang et al. 2010). In this study, we are mainly interested in the geoconservation of geosites, i.e., in activities to promote their sustainability. It is essential that the local government and population support the geoconservation of geosites and are involved in the planning and implementation of activities for the sustainability of the region (Avelar et al. 2015). The planning of activities requires an assessment of the characteristics of a geosite and potential threats to it.

In this study, we considered the physical environmental changes over the last four decades in Região dos Lagos as assessed via the use of remote sensing (Avelar and Tokarczyk 2014). Remote sensing is very useful for mapping regional changes, but is not, as yet, sufficient to characterise the impact of heterogeneous human activities on the environment (Franz et al. 2009). Anthropogenic impacts influence changes in land use and land cover, most particularly in coastal areas, which are especially vulnerable (Wang 2010, Ausness 1973). Factors driving such changes include population increase, infrastructure development, government plan and policies, lifestyle, and rural-to-urban migration (Curran and Agardy 2004, Heilig 1997). The classification results of the remotely sensed image data of the coastal area are combined with the information collected from residents of the local communities to determine the main driving forces behind changes in land use and land cover, as perceived by the communities themselves. Local knowledge of the natural, cultural, and economical particularities of the region and awareness of environmental issues are taken into consideration, as presented in Avelar et al. (2015). The key topics for geoconservation planning and sustainable development in the study area were identified, and these are used to evaluate the current sustainable state of the geosites.

The Região dos Lagos and its hypersaline lagoons are well-studied in terms of geology, hydrology, and geobiology. For example, Knoppers and Kjerfve (1999) analysed physical and biogeochemical characteristics of the lagooons; Silva et al. (2000) and Almeida and Lima (2000) investigated the hydrogeological potential of Região dos Lagos; Moreira-Turcq (2000) analysed the metabolism of the hypersaline coastal Araruama lagoon during a period with the lowest salinity conditions in the last 30 years; and Vasconcelos and McKenzie (1997) reported on the unique precipitation of microbial dolomite influenced by microbial metabolism in the hypersaline Lagoa Vermelha lagoon. However, there are only a limited number of reports on changes in land cover and land use in this coastal area, e.g., Franz et al. (2009) presented a GIS-based vulnerability analysis of Região dos Lagos based on the Pressure-State-Response-Model of OECD (1993); Avelar and Tokarczyk (2014) analysed land use and land cover changes using high-resolution remotely sensed data from 1976 to 2012; and Avelar et al. (2015) analysed community perceptions for geoconservation of this coastal area. The purpose of this study is to provide an overview of the status of sustainability of geosites located in a study area within Região dos Lagos, as a basis for geoconservation planning across the whole of the Região dos Lagos.

Região dos Lagos: a Changing Environment

The Região dos Lagos is located along the southern coastline of the state of Rio de Janeiro, Brazil. This coastal area extends from Maricá to Rio das Ostras, between 22° 52′ and 22° 56′S and 42° 06′ and 42° 26′W, and covers about 2000 km2. The area comprises many of the geosites in the aspiring Geopark ‘Costões e Lagunas do Rio de Janeiro’ (Mansur et al. 2012), which stretches from the coastal area of Maricá to São Francisco de Itabapoana in the southeastern region of Brazil, including the Região do Lagos (see Fig. 1).

Fig. 1
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Map showing the location of the aspiring Geopark ‘Costões e Lagunas do Rio de Janeiro’ and its geosites. The inset illustrates the study area and the geosites evaluated in Região dos Lagos. See Table 1 for the geosite name and description

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Geoparks have an active role in educating the public, raising awareness of environmental issues, promoting regional sustainable development, and stimulating geotourism and geoconservation at a high standard of excellence. Even if an area has an outstanding geological heritage of universal value, the area cannot be considered for inclusion in the UNESCO Global Geoparks unless the area has a plan for the sustainable development of the people living there (UNESCO 2016). It is a pre-requisite that all UNESCO Global Geoparks develop and operate educational activities to spread awareness of the geological heritage and its links to natural, cultural, and intangible heritages. Some potential geopark activities which include local inhabitants are the construction of walking or cycling trails, training local people to act as guides, and educational programs encouraging best practices in environmental sustainability. In engaging with local people, it is important to value their traditional way of life, empowering them, and respecting their human rights and dignity. Thus, the support of the local people is essential for the success of the Geopark.

Região dos Lagos has been suffering from environmental impact for many years. For example, the establishment of a national company, ‘Companhia Nacional de Álcalis’, for the production of sodium carbonate in the late 1950’s in the area (Pereira 2010a) resulted in the extraction of shells from the bottom of Araruama Lagoon (Primo and Bizerril 2002), population increase and discharge of waste into the environment. However, the major environmental impact in the region is associated with the explosive development of tourism. The land cover change in Região dos Lagos has been compiled for the period from the oldest available aerial photos, 1976, to a recent high spatial resolution remote sensing imagery of the area from 2012 (Avelar and Tokarczyk 2014). The population in this coastal area has tripled since 1976 (IBGE 2016). The urban sprawl and seasonal tourism triggers the illegal occupation of preserved areas and the removal of natural vegetation, especially on lagoon margins. This disorderly occupation by an ever increasing population, with both legal and illegal constructions, and the subsequent overload of the local infrastructure (e.g., an increase of electrical energy consumption, problems with water supply and wastewater treatment, number of vehicles, pollution of air, water and soil) are hastening the degradation of the lake ecosystem and several of the geosites in this region (Lins-de-Barros and Muehe 2010).

Land Cover Change from 1976 to 2012

Avelar and Tokarczyk (2014) carried out a detailed analysis of land use and land cover changes observed in remotely sensed images of the area of Região dos Lagos from 1976, 1990, and 2012. The general condition of land cover changes in the area was assessed using seven classes: dense vegetation, sparse vegetation, built-up areas (buildings and streets), water bodies, sand, saline (active and disabled), and bare soils. In order to identify the classes and the dynamics of land cover change in the area, standard classification methods were applied to aerial photographs from 1976 and a GeoEye image from 2012, namely, manual classification and maximum likelihood, respectively. The coastal area was still largely intact in 1976, with very few constructions in the immediate area of lagoon margins, empty parcels of land and main roads. The salt industry was the main impact on the area at that time. Sand and dunes were along the coast and also in small inland areas.

By 2012, there were mainly residential buildings distributed in the area and only patchy sections of natural vegetation remain, mostly sandbank vegetation along the beach. The coverage percentages of the classes in the aerial photographs and satellite image were calculated and are shown in Fig. 2. Bare soil has the same spectral response as sand in the aerial photographs, so it was classified as sand (Avelar and Tokarczyk 2014). Table 2 contains the magnitude of change of the classes from 1976 to 2012. Although the class proportions have relative errors incurred from the classification (Congalton 1991; Okeke and Karnieli 2006), the land cover change proportions do indicate where development pressures occurred over this period of time.

Fig. 2
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Area percentages of land cover classes in the aerial photos (1976) and GeoEye image (2012)

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Built-up areas increased substantially from 1976 (5.28%) to 2012 (20.63%) by replacing areas of dense vegetation, sand/bare soils, and saline. Many salt works ceased operations with the end of profitability of the local sodium carbonate industry in the 1990’s (Pereira 2010b). A large deactivated salt work area, which supplied the local salt industry, is a matter of concern because no social and environmental criteria for it had been systematically planned. Furthermore, areas that should be protected by virtue of being located in a State Park have also been occupied with illegal constructions. These changes are approaching a critical threshold, as only a few preserved areas in the immediate coastal boundary and some private properties remain free of occupation.

Assessing Sustainability Issues at the Geosites

In order to make urban and rural environments more sustainable for future generations, many sustainability issues have to be considered. We evaluated the sustainability of the geosites in our study area, using the key topics for geoconservation and sustainable development of localities as assessed by Avelar et al. (2015), which can identify the main human activities impacting the environment as perceived by resident communities in this coastal area. Thus, using such key topics to assess sustainability issues of a geosite, we have an indication of major environmental and social issues that require corrective actions, policies, government investment, and the support of activities from the local population for the specific geosite. The topics are described in Table 3. Through the implementation of activities in these specific topics, communities can monitor the sustainability of local geosites.

The most relevant topic for geosites is land use and biodiversity, but activities in all topics should respect and protect the natural characteristics of geosites. For geosites located in urban areas, all key topics can be used to evaluate the sustainability of geosites. For geosites in rural environment, topics, such as wastewater treatment, urbanisation, and urban mobility, do not directly apply.

We evaluated 10 geosites in the study area, which were chosen due to their scientific value and proximity to touristic coasts. The selected geosites were Lagoa Vermelha, Brejo do Espinho, Serra da Sapiatiba, Ilha do Cabo Frio, Dama Branca Dune, São Mateus Fort, Boca da Barra Park, Peró Dune, Mangue de Pedra, and Rasa Beach (see Table 1) (Mansur et al. 2012). The assessment of the key topics (see Table 3) for the 10 geosites was carried out by 10 evaluators, who work as conservation unit managers or scientific researchers in the area and are familiar with Região dos Lagos. The existing activities in all key topics were evaluated for the geosite area as they were perceived by the evaluators. The evaluators listed for each key topic whether sustainability activities exist, partially exist, or do not exist. The analysis of the evaluators’ answers employed the statistic technique ‘mode’ to identify the answer that appeared most frequently. The statistic mode is especially useful when the range of possible answers is small, as in this case. When different answers for a topic occurred the same number of times, we interpreted it as ‘exists in part’. The result of this evaluation of geosites is presented in Table 4.

Table 1 The main geosites in the aspiring Geopark ‘Costões e Lagunas dos Rio de Janeiro’
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Table 2 The rate of land cover change in the period of 1976–2012 in Região dos Lagos
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Table 3 The key topics for evaluating sustainability issues of geosites (Avelar et al. 2015)
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Table 4 Evaluation of sustainability issues at 10 geosites in the study area
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In most localities of the study area, we have, in general, a low grade of sustainable development. São Mateus Fort is the only geosite located in an urban area and activities in all key topics were positively perceived, giving it a grade of 10, which indicates it has sustainability. All of the other geosites are located in rural areas and even though they are under protection by federal and state environmental laws, they have been suffering from the effects of environmentally negligent touristic investments in this coastal area. The geosites that are most threatened are the ones with the least ongoing activities in their sustainable development. They are Brejo do Espinho, Peró Dune, Lagoa Vermelha, Dama Branca, and Mangue de Pedra.

The sustainability of the entire Região dos Lagos is threatened by many damaging human activities, compounded by poverty and irresponsible management by the local authorities. There is no evidence that the current protection laws have any effect in inhibiting deforestation along the coast, as the urban growth is advancing on areas of high landscape value, such as the sandbank between the sea and Lagoa Vermelha. This sandbank is the extension of Restinga de Massambaba and is an important natural heritage that is becoming urbanised (Teixeira 2012), or, more accurately, ‘slumized’. Despite existing preservation programs, land speculation is still one of the major economic activities in the region today. All geosites need to be monitored in a general planning of the aspiring Geopark ‘Costões e Lagunas dos Rio de Janeiro’. Deforestation, land speculation, illegal occupation of dunes, removal of sand, and illegal burning are leading to the devastation of the natural flora and fauna.

The municipal authorities have to be encouraged to implement activities addressing the key sustainability topics that are deficient in the geosites areas. This would be especially important for topics related to the severe changes identified by the remote sensing analysis, which are in the ‘built-up’ class. The topics related to this category are urbanisation, urban mobility, waste, and wastewater treatment. Such topics do not have relevance to geosites located in rural zones. However, as these geosites are expected to receive tourists, a system for the collection of waste should be also planned for these geosites.

Although Brejo do Espinho and Lagoa Vermelha are not located in urban areas, they are close to a popular coast and have artisanal salt works and residences along their margins (Avelar et al. 2015). They are also threatened by construction plans in the process of being approved. In case of Brejo do Espinho, the construction of a tourist resort on the margins of the lagoon was approved by the licensing office of the state government of Rio de Janeiro. In order to prevent the construction of the resort, administrative steps, including a technical analysis of the project and its possible impacts in the environment, were taken (MPRJ 2012, RAP 2012). Nevertheless, a licence was granted.

The Peró Dunes have not, however, as yet, been destroyed because the local population, NGOs and the scientific research community carried out an intensive campaign, which resulted in the temporary stop of the building work in the area (Mansur and Carvalho 2011). The anthropogenic impacts of land occupation can have consequences in the physicochemical conditions of the lagoons and coastal system (Costa et al. 2008, PMSBS 2014, Lima et al. 2013). In the case of Lagoa Vermelha, this put at risk the ideal conditions for maintaining living stromatolites (Höhn et al. 1986). The town hall of Búzios did not turn the Mangue de Pedra area into a conservation site and new constructions continue to be extended over areas of groundwater charge and discharge. The Mineral Resource Department of Rio de Janeiro (DRM-RJ) has organised meetings and activities with the local population and NGOs, where a proposal for a project to establish a local park has been formulated. However, to date, these initiatives have not, as yet, been successful in altering construction planning for the region.

Local communities expect to see benefits in the geosite areas, such as improving public areas, recreational activities, and education opportunities. Those benefits mostly depend on decisions to be made by public authorities and well-elaborated strategic plans, which can support short- and long-term geoconservation activities.

Education for Sustainability

A sustainability strategy for geosites has to set the model and process for establishing the three pillars of sustainable development: social, economic, and environment. Learning to live together sustainably in urban and rural environments is one of the most important educational challenges of our time (UNESCO 2016). The identification of responsibilities at regional and national level, land-use planning, empowering citizens with information, indicators and maps are essential tasks. The stated commitment of the aspiring Geopark ‘Costões e Lagunas do Rio de Janeiro’ to social and environmental development should cross the boundary of academia and be matched with action. Education for sustainable development should be promoted as a linking theme in all the key sustainability topics in Table 3.

Educational projects have been conducted in schools in various municipalities of Região dos Lagos to raise an awareness of the natural environment with the local community and also to promote the aspiring Geopark ‘Costões e Lagunas do Rio de Janeiro’. Training courses in geosciences and geoconservation prepare teachers of primary and middle level schools to disseminate concepts and to help preserve the existing geosites. In addition, a children’s book (Vasconcelos 2015) was written to explain the basic processes of formation of the Earth, the origin of the moon, volcanoes, the formation of rocks, the appearance of water and earliest forms of life, and the main natural elements of the Earth. These phenomena are described through the main characters of the book, the ‘super spheres’: atmosphere (air), lithosphere (rock), hydrosphere (water), and biosphere (a stromatolite and a dolomite mineral), which are the four components of the Earth system, and also Pyrosphere (fire), which supplies the energy to drive the Earth system through volcanic activity (see Fig. 3). The characters appear in a specific chronological order, each having super powers that evolve over geological time. The story focuses on the rescue of the super spheres, which are in danger and need to be saved. Through these stories, children can learn the importance of geological heritage and help to preserve the planet.

Fig. 3
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Characters created to support the education of children in geosciences and increase their awareness of sustainability issues (Vasconcelos 2015)

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The actual geosites should be used to train tourists and also students from surrounding schools and universities. Awareness about the importance of geosites and their need of preservation should be consolidated for medium and long-term inclusion in educational programs. Doctorate and master thesis have been prepared on the subjects of geoeducation, geodiversity, and biodiversity in the aspiring Geopark. The financial support for educational projects has been provided mainly by Brazilian agencies for promoting science and technology and the Brazilian oil company Petrobras. Working together with the government and NGOs has been the solution to maintain and promote the proposal for the aspiring Geopark. Social media has been used in collaboration with NGOs and society in general to inform the activities happening at geosites and describe actions to help to preserve the geosites.

Conclusions

The increasingly problematic interaction between people and the physical environment and the need for sustainable development of environmental areas are vital themes in today’s world. We assessed 10 geosites located in Região dos Lagos, in order to identify specific issues that should be prioritised in the sustainable development of the region.

With land cover and land use classification of imagery data from 1976 and 2012, we determined the amount and speed of physical changes in the study area. Combining the classification results with local knowledge about the natural environment and socio-economic aspects of the region helped to understand the ongoing dynamics and potential trade-offs between human and environmental factors. The key topics used in the evaluation of geosites allowed us to identify priority subjects for the sustainability of the geosites, as well as to track various municipalities’ progress towards the goals identified by the local communities.

The main driving force to changes in land cover and land use over the last four decades in Região dos Lagos was the uncontrolled increase of built-up areas which are detrimental to dense vegetation, salinas, and bare soils (Avelar and Tokarczyk 2014). The lack of land-use planning and protection of biodiversity, insufficient transport infrastructure, inadequate sewage disposal, poor waste treatment, and the lack of awareness of the local population about environmental matters are also impacting the environment of Região dos Lagos. The absence of an effective housing policy is a major problem in the occupation of the area, because the degradation processes underway in Araruama Lagoon and surrounding dunes can reach unrecoverable levels. Due to the uniqueness of this coastal area, it is urgent to tailor geoconservation activities to specific sustainability issues at geosites.

Urbanisation in coastal areas often leads to destruction of sensitive ecosystems and can also alter the hydrology system of the coast and its natural features. This study provides important insights to assist municipalities in taking control of the consequences of the loss of natural vegetation in Região dos Lagos and to protect the remaining areas, highlighting the role of geoconservation for future generations. If municipalities are properly managed, with an adequate attention paid to their environmental protection and social development, many of the present problems resulting from rapid urbanisation can be avoided.

Awareness of sustainability issues is essential to help to connect human development with the environment’s capacity to sustain progress. Together with the establishment and continuous monitoring of geosites to achieve the sustainability of the region, educational projects are needed for the awareness and dissemination of scientific knowledge. Besides providing the public with easy-to-understand information about sustainability issues, existing problems and challenges, educational projects are a form of empowerment of the local society. Although such projects have been implemented in the region, they cannot yet reach the general public living in the whole area. Educational activities for children and adults, both formal and informal, are essential for the public understanding of geoscience and the promotion of geoconservation of the Earth’s heritage and for the sustainable development of the area. Brazilian environmental control agencies also need to be more involved with the protection of geosites, especially because the population perceives the agencies as more involved with the economic prospects of real estate investments. Permanent management and appropriate financial support are also required for the establishment and continuation of the aspiring Geopark ‘Costões e Lagunas do Rio de Janeiro’.