ANTROPICOASTS BUILDING: THE CASE OF SEPETIBA (RIO DE JANEIRO,
BRAZIL)
Silvia Dias Pereira1, Maria do Rosário Bastos2, J. Alveirinho Dias3, Hélio Heringer Villena1,
Aline Freitas1, Iná Barros1, Thayse Alves1
1: Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rua São Francisco
Xavier, 524 Sala 4031E, Rio de Janeiro, RJ, Brasil, CEP 20550-013, [email protected]
2: Depto. de Ciências Sociais e de Gestão Área de História, Universidade Aberta – Delegação
do Porto, CEPESE, [email protected]
3: CIMA – Centro de Investigação Marinha e Ambiental, Faro, Portugal, [email protected]
RESUMO
CONSTRUÇÃO DE ANTROPICOSTAS: O CASO DE SEPETIBA (RIO DE
JANEIRO, BRASIL)
A Baía de Sepetiba junto com a Baía de Ilha Grande integra um vasto complexo
costeiro do litoral do Estado do Rio de Janeiro. Localiza-se entre as latitudes de 22º54’06” e
23°04’18” S e as longitudes 43°03’42” e 44°02’03” W.
O primeiro modelo evolutivo para a Baía de Sepetiba e Restinga de Marambaia foi
proposto por Alberto Lamego em 1945. O fechamento da "baía" teria ocorrido através do
crescimento de um grande tômbolo que teria se formado de oeste para leste, a partir da
deposição de sedimentos arenosos trazidos pelos rios Guandu e Itaguaí, impedidos de serem
carregados rumo a Baía de Ilha Grande pelo cordão de ilhas existentes a oeste. O crescimento
da restinga conduziu à formação de um litoral abrigado, por isso, extremamente atrativo para
a captação e fixação o Homem. Da detecção da presença de comunidades índias, passando
pelo período colonial e até a atualidade, este trecho do litoral foi revelando um crescente
ritmo de intensificação antrópica. Assim, se até a chegada dos europeus, há cinco séculos, a
Baía de Sepetiba se encontrava praticamente em estado prístino, no presente está
profundamente antropizada (poluição química, poluição biológica, artificialização das
margens, alterações no meio hídrico, etc.). Desta forma, o caso em análise constitui um
excelente exemplo para se estudar de que forma o Homem modifica, através das suas
atividades, os ambientes naturais.
Palavras-chave: Zonas costeiras, interações Homem-Meio, sedimentos, ocupação humana,
ABSTRACT
Sepetiba Bay with the Ilha Grande Bay is part of a vast coastal complex of the littoral
of Rio de Janeiro State. It is located between the coordinates of 22°54'06” and 23°04'18” S
and of 43°03'42" and 44°02'03” W.
The first evolutionary model for Sepetiba Bay and Marambaia Barrier was proposed in
1945 by Alberto Lamego. The closing of the "bay" would have occurred through the growth
of a large tombolo that would have been formed from west to east, with the deposition of
sandy sediments brought by rivers Guandu and Itaguaí, blocked from being loaded towards
the Ilha Grande Bay by the islands in the west. The growth of the barrier led to the formation
of a sheltered coastline therefore extremely attractive for the capture and fixation of Man.
From the detection of the presence of indian communities, through the colonial period and
until the present time, this stretch of coast was revealing a growing pace of anthropogenic
intensification. Therefore, if until the arrival of europeans, five centuries ago, the Sepetiba
Bay was virtually in pristine state, in present time it is very much disturbed (chemical and
biological pollution, artificiality of margins, changes in the water environment, etc.).. Thus,
the present case is an excellent example for studying how humans change, through their
activities, natural environments.
Keywords: Coastal zone, Man-Environment interactions, sediments, human occupation
INTRODUCTION
Sepetiba Bay is set in a coastal segment that includes, among others, Ilha Grande Bay
and Angra dos Reis (Figure 1). Although it was not the objective of this work the analysis of
the system eluded ago, it is important to note that the evolution of Sepetiba can only be
properly understood if we have in mind that it is only one element of a whole, resulting from
anthropogenic and geodynamic processes occurring on barlamar (Roncarati and Barrocas,
1978). This fact allows, for example, understanding the mechanisms of growth of Marambaia
Barrier that separated the bay from the Atlantic Ocean (Roncarati and Barrocas, 1978 and
Lamego, 1945). Similarly, settlement and exploitation of natural resources should be analyzed
in an integrated manner, since the whole system has influenced and conditioned the human
interventions during the pre, proto and historical period. Just for a methodological issue, we
will focus the analysis in Sepetiba, staying however the alert that this is a piecemeal approach
that requires new studies to provide a comprehensive understanding of the area in question.
Between the coordinates of 22°54'06" and 23°04'18” S and of 43°03'42" and 44°
02'03” W (Figure 1), Sepetiba Bay is one of the three large bays of the coast of Rio de
Janeiro State (in conjunction with Ilha Grande Bay in the south and Guanabara Bay in the
north). Corresponds to an initial and still unfinished stage of the correction of coastal sandy
bands Lamego (1945), compared to more mature phases found in the east, represented by the
lagoons of Marica, Saquarema Araruama, Jacarepagua and others.
Figure 1 - Location of the study area
The Bay has an ellipsoidal shape with 40 km long and 16 km wide. The lower depths
and lower slope angles are located in the east section, which is the bottom of the bay. In the
central section of the bay there is an elongated depression with depths that reach 8 meters. It
also presents three channels in its western section: the first in the entrance of the bay to the
southern of Guaíba Island, with a maximum of 31 meters deep; the second and main, between
Itacuruçá and Jaguanum Islands, with maximum depth of 24 meters; and the third between
Itacuruçá Island and mainland, with 5 feet depth (Borges, 1990). At Sepetiba Bay flock
several rivers (Guandu, Açú, Itaguaí...) born in Serra do Mar and that cross in the downstream
area, a floodplain (Baixada de Sepetiba). The quieter water of the bay, added to the protection
provided by Marambaia Barrier, associated to river estuarine areas which were routes of entry
into the interior, inducing easy irrigation of cultivations, certainly potentiated the human
occupation of the section in question. Then, they could develop and exploit natural resources
with a minimum of safety (reduced exposure to activities of piracy and corso, existence of
natural harbors, etc.). Thus, it is not surprising that Sepetiba Bay registers remote traces of
human presence, evidenced in the indian occupation, as evidenced by the presence of
“sambaquis” in the region. From then until today, all this coastal subsystem never ceased to
be subject to the impacts of human activities that have been intensified with the course of time
until present; they have probably exceeded the level of system resilience.
The work was based on interpretation of historical cartography from sixteenth century;
in the research of manuscript maps of the early eighteenth century; in the heuristics and
hermeneutics analysis of historical sources (manuscripts and printed: periodic and non
periodic) regarding to the study area; and analysis of cores.
We made a stratigraphic sedimentary correlation defined in cores, with anthropogenic
activities developed in the draining basin.
In this context, this study aims to identify the interdependencies between the
morphodynamics of Sepetiba Bay and the human occupation in this bay and its surrounding,
since
the
region
began
to
be
explored
by
europeans
until
today.
Physical Characterization
The first evolutionary model for Sepetiba Bay and Marambaia Barrier was proposed
by Alberto Lamego in 1945 (Figure 2). The closing of the "bay" would have occurred through
the growth of a large tombolo that would have been formed from west to east, with the
deposition of sandy sediments brought by rivers Guandu and Itaguaí, blocked to be loaded
towards Ilha Grande Bay by the islands in the west.
The climax of the Flandrian transgression, which would have reached 4 to 6 feet above
the current level, led to the formation of a large inlet in the actual area of Sepetiba Bay. In the
shore of the bay, the processes of coastal dynamics would have caused a series of beach
ridges of inlet, as well as the formation of a constructive delta type cuspidate. In the north of
this inlet the river system, implemented in the Guandu River Lowland and others, developed
deposits of fluvial environment whose traces in the form of meandering and anastomosing
channels are still visible in aerial photographs.
Figure 2 – Evolutionary model to Sepetiba Bay and Marambaia Barrier (Lamego, 1945)
To Roncarati and Barrocas (1978), coastal currents moving from west to east and
passing by the large opening of the inlet, would form in the internal waters, by simple friction,
circular currents that would carry the fluvial sediments deposited in the north of the inlet by
the rivers that flow there. The meeting of two currents, the coastal and the circular internal in
the inlet, forms a dead water zone initially lying to the east of the Marambaia Peak.
The Marambaia Barrier has length about 40 km and maximum width of 5 km. In
certain sections of its central part it is reduced to a narrow band of only about 100 meters
The topography of the barrier is smooth, just been observed a higher elevation with
640 meters in its western portion, represented by the rocky ridgepole of Marambaia Peak that,
according to Lamego (1945), have been an anchorage to the quartz-sandy body of the barrier,
which was constructed by the action of ocean currents. In the central part, more narrow, we
observe the characteristic "channels and washover fans", originated by the action of tides and
storms (Moura et al., 1982).
With few feet above the medium level of high tide, the barrier island has in its eastern
portion an area of dunes, and internally, bands of silty clay plains covered in part by
mangroves. Moreover, any tidal channel sections this sandy body, due to the tidal regime of
low amplitude (less than 2 meters). During heavy storms occur washovers (washover
channels) at some points of its central part, with the transport of sediments of the barrier and
marine into the lagoon (washover fans).
It is in pursuit of the establishment of a protected coastline, resulting from the
development of the Barrier, which we explain the attractiveness found in the occupation and
anthropic intervention in Sepetiba Bay (Figure 3). This was the scene of many events in the
Brazil History, and today maintains its importance as a place of vigil in front of the Santa
Cruz Air Base. From the indian occupation, to the imperial and colonial period, the story of
Sepetiba is directly related to the Brazilian commerce and more specifically of the Rio de
Janeiro State, and also with the vicissitudes of the presence of the Portuguese court, and after
the independence, of the Brazilian Imperial House.
Figure 3 – Map of Teixeira Albernaz I (1666)
The antropization of Sepetiba Bay
Until the arrival of europeans, the region was basically in pristine condition, due to the
kind
of
life
the
natives
had,
inducing
minimal
impact
on
nature.
With the arrival of europeans in the sixteenth century, the situation began to change rapidly.
The exploitation of Brazil wood (Goes, 1942) and other woods certainly induced significant
environmental impacts, both forest and in the bay, as it constituted a factor of silting up.
In the second half of the sixteenth century, the entire region in question was occupied
by a large farm called Farm of Santa Cruz, whose story begins in 1567 when Cristovão
Monteiro gets an allotment of four leagues, which extends from Sapeaquera (Itacuruçá) to
Guaratiba (ibidem.). In the seventeenth century the Fathers of the Society of Jesus extended
the area of the farm making it big landowners. Regarding the holding of Santa Cruz, it is
noted that the Farm, "owned by the Jesuits, (...) knew in the first half of the seventeenth
century an intense period of development of farming and livestock" (Viana, 1974). In the
eighteenth century, the farm had become huge, with about 2167 km square. The farm was the
first elements of environmental change in the region and in the Sepetiba Bay, due to the
intensification of the sedimentary cycle induced by the main activities that were being
developed there, with particular relevance with regard to agriculture and grazing lands. The
analysis of cores collected in the eastern part of the bay can reveal that the sedimentation
began to intensify at this time.
With time, the intensification of deforestation and the increase of agriculture and the
mining activities resulting in the hydrographic basin, besides other activities (including
construction of accessibility and urban development) have been gradually increasing, with the
consequence of the strong increase of sediment loads affluent to the Bay and consequent
silting up.
The imperial period was only a new stage in the process of formation of this
antropicoast segment. In fact, the location and strategic importance of Sepetiba Bay, led D.
João VI to conclude that this would be an appropriate place for shipping and runoff of
products. Sepetiba was then considered the "Port of Gold" which received the gold that came
from Paraty to Lisbon, becoming the most important port exporting gold from Brazil during
the colonial period (Wilde, 2008). Besides gold, it was drained from Sepetiba the Brazil wood
(abundant in the forests of the region) and the slaves who were thus directed by sea to Sao
Paulo and Minas Gerais, which shortened the distances (ibidem.). Attracted by greed,
Sepetiba Bay was the scene of many battles between corsairs and soldiers of D. João VI. It is
not yet measured the importance all this activity had on the silting up of the bay, but it is
legitimate to assume that the operations of the vessels had great importance.
After D. João VI decree promulgating the law of 1813 giving the land to fishermen
and farmers that came to the region, things have been modified. The area of old farm of Santa
Cruz was divided into sites that have been donated to individuals. Seeing the vulnerability of
the region in case of invasion, D. João VI ordered that two forts were built to defend the bay,
and its commerce: Fort of São Pedro and Fort of São Leopoldo. Consequently it was
intensified the occupation of this region, which increased the environmental impacts,
including the level of silting up in the coastal environment reference.
During Republic period, some fishermen and farmers of other localities were fixing up
near the beaches of the region building a few small houses of cob wall, which were covered
with “sape” (Wilde, 2008). The development of these small urban fishery centers contributed
significantly to the modification of characteristics of the coast of the bay, being a relevant
factor
to
disturbance
of
its
margins.
Located almost at sea level, cut by rivers, canals and gutters that drain into the Sepetiba Bay,
in the extreme west of the current municipality of Rio de Janeiro, the old Royal Farm,
Imperial and National of Santa Cruz, current Agricultural Colony of Santa Cruz has suffered
with some frequency the phenomenon of flooding, causing partial or total loss of their crops.
Throughout its existence, many families had to leave their homes in search of a safe harbor
(Souza, s.d). It was, of course, in these periods of heavy rain that most of the sediment was
eroded and transported to the bay silted up progressively, antropization it, when the causes
and intensity of this silting up were largely anthropogenic.
Today, the growth of urban areas, the development of industries, the construction of
roads and of railway as well as the building of dams in the hydrographic basins that drain into
Sepetiba Bat (particularly Guandu River), led to an apparent modification of river systems
and a change in the coastal environment and consequently the establishment of new
relationships between Man and Nature.
RESULTS
In the development of the coastal plain of Sepetiba area can be considered two great
cycles, quite distinct, characterized by a transgressive event followed by a regressive, with
two smaller transgressive events included in this regression.
According to several authors, in the last glacial hemicycle (11,500 years BP), the
actual shoreline of the Brazilian coast was exceeded for the first time about 6500 years BP,
keeping in submergence to 5100 years BP, followed by a regression with two short periods of
transgression.
Since then, there has been occurred characteristic sedimentation of the lagoon area, at
low energy environment and typical sedimentation of mangrove.
The age determined for the beginning of the deposition of this layer is of 565 years BP
indicating a sedimentation rate (Figure 4), based on data from the core, of 0.32 cm / year to
1.82 meters in deep and 0.06 cm / years from 1.82 to 5.30 meters in depth, considering the
estimated age for the base of the same core, of 6130 years BP (Figure 5). The sedimentation
rate characteristic of mangrove, 0.1 to 0.8 cm / year (SCHWAMBORN and SAINT-PAUL,
1996), fits into the first interval. We can consider that the human occupation accentuates this
sedimentation rate.
Figure 4 – Sedimentation rate in core D (changed from Coelho, 1999)
Considering the problem of the transgressive and regressive phases, pointed in the area
of Sepetiba, in the evolution of the Quaternary in the Coast of Brazil, we can estimate that
they concern to the last episodes of the Quaternary, corresponding to the Holocene High
Marine Level or Santos Transgression.
The results of radiocarbon dating analysis showed consistent results for the core,
confirming the events already recorded in literature: 6130 years BP for the transgressive
environment of bay bottom (base of the core).
About the antropization of this coastal zone concerned, we may say that the fact of
this being a sheltered coastline and, therefore, safer, favored the establishment and
development of human populations. Moreover, its strategic position, immediately south of the
city of Rio de Janeiro, associated with the fact that this is an area of good accessibility via the
channels that cross the marshland to recede in Sepetiba Bay, was also extremely important for
the affirmation of an intense commercial activity. This trade could be legal or illegal. Often,
Sepetiba worked as the back door of Guanabara.
Figure 5 - Data of a core collected in the area
The construction of new access and increased exploitation of natural resources, led
to an intensification of the human disturbance of Sepetiba Bay, until the extent permitted by
nature.
CONCLUSIONS
Sepetiba Bay is a paradigmatic example of how a coastal geomorphology accident,
constituted exclusively as a result of natural processes, can quickly get new environmental
characteristics, with its evolution being determined, mainly, for the consequences of anthropic
activities.
Indeed:
a) Sepetiba Bay as the first europeans to have known, still in pristine condition, was the result
of a natural evolution in which changes of the sea level mean (SLM) had preponderant
importance: a transgressive cycle in which the SLM reached a maximum of about 4.8 meters
above the current level about 5100 years BP; a regressive cycle began about 4900 years BP
and that would have ended around 2000 years ago, after which SLM stayed relatively stable;
b) with the exploitation of the Brazil wood and other woods by the first europeans in the
sixteenth century, began antropization of the area in question, including the intensification of
the silting up of the bay;
c) the formation of Santa Cruz Farm in the mid-sixteenth century, with a corresponding
intensification of agro-livestock was the major factor modifying natural morphodynamics,
with a strong intensification of the silting up of the bay and expansion of mangroves areas on
its periphery;
d) in the nineteenth century the dismemberment of the Santa Cruz Farm and intensification of
the occupation both in the hydrographic basin draining and the margins of the lagoon had as
consequence a greater artificialization of the coast and growth of the rates of silting up;
e) the building of new access (roads, railways, ports), followed by widest territorial
occupation and corresponding urban development amplified the rates of silting up of the bay
providing also greater development of the mangroves;
f) in the twentieth century trends alluded above have intensified, and should be highlighted
the port component industry, which emphasizes Inga industry and the strong pollution
associated, with contamination of the coastal marine environment and its margins;
g) the bay is currently very silted up, mainly in marginal areas, beyond in some areas the
levels of contamination are relatively high; by the current characteristics, the forcing of the
recent evolution and by the level of artificialization of its margins, Sepetiba Bay is strongly
impacted and can be truly considered as antropicoast.
ACKNOWLEDGEMENTS
The authors thank FAPERJ for their support through research assistance (APQ1) and
CEPESE / Portugal for the release of researchers to develop of the research project.
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