Journal of Coastal Research
1087 - 1089
SI 39
ICS 2004 (Proceedings)
Brazil
ISSN 0749-0208
Distribution and Caracterization of Environments Used By Otters in the Coastal Region of Santa Catarina State, Brazil O. Carvalho Junior†; N. M. S. Banevicius† and E. O. Mafra† † Centro de Ciências Tecnológicas da Terra e do Mar CTTMar, Universidade do Vale do Itajaí UNIVALI. Itajaí, SC 88302-202, Brazil.
[email protected];
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[email protected] ABSTRACT CARVALHO JUNIOR, O.; BANEVICIUS, N. M. S. and MAFRA, E. O., 2006.Distribution and caracterization of environments used by otters in the coastal region of Santa Catarina State, Brazil. Journal of Coastal Research, SI 39 (Proceedings of the 8th International Coastal Symposium), 1087 - 1089. Itajaí, SC, Brazil, ISSN 0749-0208.
Studies related to the distribution and characterization of environments used by otters in the coastal region of Santa Catarina State has been conducted since 1999. Three different habitats are monitored: a river, a coastal island and a freshwater lake. Characterization of otter's shelters in the three environments related to the organization and use of the internal space is realized. One of the shelters has its temperature monitored in order to describe the relation of the frequency of use by the animal. The analysis of the diet of the specie together with visual observation is used to infer about the social organization. A close relation between the shelters with the geology and vegetation is found. The main preys of the otters indicate that it is basically a lonely animal. Depending on the season it can shows a group of two to four individuals. The preliminary results can be used as an indication to future measures related to the preservation and conservation of otters in the state. ADDITIONAL INDEX WORDS: River otters, Lutra longicaudis, ecology of otters, shelters.
INTRODUCTION This work is a descriptive study and analysis of otter shelters for 3 different environments: a fresh water lake (Lagoa do Peri), a coastal island (Ilha de Porto Belo) and a river (Morro dos Macacos). These three places are important ecological units in the Santa Catarina State, South of Brazil. The lake, located at Santa Catarina Island, has beenis part of a local park since 1978 and is also, aimed to be a source of fresh water supportingo increment the accelerated urban development of the south part of the Island. The river is part of into the Camboriú River basin, which is also a source of fresh water for the cities of Camboriú and Camboriú Beach. The island belongs to Porto Belo city and is represents a tourist center hosting, with a large number of visitorstourists during summer. The study areas are inside a subtropical region, humid and with pleasant mild temperatures. The precipitation is well distributed during the year with a maximum during summer and a minimum during winter, without a dry station. Small thermal oscillations are observed during the year, due to the proximity of the ocean. Average annual temperature varies from 16.4°C in winter to 24.3°C in summer. The predominant winds are from NE and N, but the wind from the south is normally more intense and can cause quick dropschanges, resulting in low temperature. The solar radiation is distributed along the latitudes, with values from 1800 to 2000 hours per year. The predominance of moderatelight temperatures throughouttrough the year, associated with a geographic variation of solar light and the presence of the ocean, results in fairly constant relative humidity average values of relative humidity relatively constant around 85% (GAPLAN, 1986). In Brazil, few workstudies have been published about otters have been done, among them, CARVALHO-JUNIOR (1990) , that showswith a detailed study of the ecology of Lutra longicaudis in the Lagoa do Peri. OLIMPIO (1995) and SILVA JUNIOR (1988), discussed the distribution of Lutra longicaudis in Santa Catarina State. More recently, PARDINI and TRAJANO (1999) studied otter shelters along Betari River in São Paulo state. Researches of otters, oOutside of Brazil, much otter research has been conducted, for exampleare common such as: BLUNDELL et al. (2002), JAMESON (1989), MELQUIST and HORNOCHER (1983), HARPER (1985) and NICKERSON (1984). The importance of shelters related to the number of otters (PARDINI and TRAJANO, 1999; CARVALHO JUNIOR, 1990 and
KRUUK et al., 1989), associated with the local geology and the Atlantic Forest, has been demonstrated by CARVALHO-JUNIOR (1990). The distribution of rocks, associated with roots and epiphytes, results in a protected environment from the weatherwheatear. The way that the animal can make use of these environments can be very complex, including the use of emerged and submerged entries, besides the existence of underground galleries connecting two or, some times, three caves (CARVALHO-JUNIOR, 1990). Otter's shelters distribution in the study area have beenwere done before by CARVALHO-JUNIOR (1990) and SCHMIDT et al (2000). However, comparative studies of otter shelters wer have not been donestudied before. From these results, it is its possible to define an otter habitation pattern associated with the habitat type and the environmental variables involved.
METHODS Preliminary studies included visual observation and checking for faeces end footprints. For each habitat a shelter was selected in order to obtain a detailed internal description. The location was determined with a Global Positioning System (GPS 12 CX) - Garmin with 12 channels, datum Córrego Alegre and a resolution of about 15 meters. The number and location of the emerged and submerged entries are defined for each shelter. The drawings are done using a Wacom digitalize table .
Figure 1. Spatial organization of otter shelters. (A) Peri Lake; (B) Porto Belo Island; And (C) Macacos Mountain. A1, A2: Entrance above water level. A3: Submerged entrance. The drawings are not to scale. Measures are in centimeters.
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Figure 2. Distribution of shelter, air and water temperatures along the year. One shelter is selected to monitor the air, water and shelter temperature. Temperatures are obtained monthly for a period of 48 hours, in which every 6 hours the data is collected and monitored at. Temperatures are organised as: 06:00, 12:00, 18:00 and 24:00 hours. A rowing boat, photographic camera, tape measure, torches and diving equipment are used to visit and study the areas.
RESULTS AND DISCUSSIONS Figure 1 shows the shelters, with measurements, for each area of study, Peri Lake, Macacos Mountains and Porto Belo Island. The heighthigh of the internal rooms vary from 1,25 to 1,60 m, with widths between 3,25 and 3,70 m, and lengths from 3,50 to 6.40 m fort the shelters located at the Peri Lake and Porto Belo Island. At the locality of Macacos Mountain location heights were below 1 meter, but with widths and lengths similar to the one found in the other study areas. The shelters described for the three environments are similar as regards, concerned to their structure and the geological formation. This is due to the homogeneity of the geological formation along the coast of the state, constituted of a crystalline complex, represented by intrusive granites of the Pre-Cambrian Era (GUERRA, 1966). The original disposition of the rocks favors the formation of semi-closed internal environments semi-closed, some times connected and , frequently, divided in compartments. All the shelters present several emerged and submerged entrances emerged and submerged. The external area of the shelters is covered by typical vegetation of Dense Ombrofila Forest (Rain Forest), which that occupies areas with high inclination. This is a tropical forest that can be found along the Atlantic Basin. TodayNowadays, this forest occupies only 1/3 of the surface of the state (BEGE, 1996). The main characteristic of this forest is its stratification with a presence of high density of epiphytes, especially bromeliaceous. The roots and a thick layer of humus work together to fill space left by the rocks disposition. The interaction between the geological structure and the vegetation, guarantee a protected environment against the local wheatear, such as rain, wind and cold. This also results in an environment with a very low luminosity when compared to the external area. The roof of humus and vegetation work as a moderator of temperature. As a result, temperature remains more stable along the year. Figure 2 shows the distribution of temperature inside an otter shelter at the Peri Lake compared to the outside air and water temperature. All temperatures show a similar trend, with a minimum during July (winter) and a maximum during February (summer). In winter the internal temperature is higher than air and water temperature, which could indicate the shelter as comfortable and protected environment for the otter to rest and protect itself against the unfriendly weather conditions. On the other hand,
Figure 3. Distribution of temperature inside an otter shelter at the Lagoa do Peri at 4 different hours of the day : 06:00, 12:00, 18:00 and 24:00hs. during the hot summers, internal temperature is mild, around 26°C, in-between water and atmosphere temperatures. The rocky structure works as a source of heat during winter and as a cooler in summer. Internal temperatures, however, could be much higher or lower was if it not wouldn't befor the presence of small entrances connecting internal and external areas. Figure 3 shows the distribution of shelter's temperatures fro every 6 hours in a cycle of 24 hours. It can be seen from Figure 3 that the temperature inside the shelter tends to follow the path of the solar radiation achieving its been maximum during summer and decreasing throughout the winter. The difference between maximum and minimum temperature through the year is 8°C at 6:00hs, 6.2°C at 12:00hs, 9.5°C at 18:00hs and 9.5°C at 24:00hs. The internal area is spacious (see Figure 1), with height that can allow an adult human being to stand remain inside comfortably stand or sited. The combination of various small and various entrances with the internal space isare important for the thermal regulation of the shelter. In fact, these small entrances also work as regulators of internal luminosity and heat. The several height levels of the internal rooms result in a better use of the internal heat by the animal. During summer, the shade provided ow given by the forest and, plus the presence of humus and bromelias, are of fundamental importance to prevent the overheating inside the shelter. As can be observed in Figure 2, the temperature inside the shelter at 12:00 hours and at 18:00 hours is always lower than the air and water temperatures. On the other hand side, the rocks in front of the shelter entrance work as a solar area, collectingors of solar heat and being , that used by the otter use to dry itself under the sun and to do its cleaning itself, especially during winter when the rocks continue to irradiate the heat from the hours of solar radiation (CARVALHO-JUNIOR, 1990). The forest itself, during winter, can help to keep the heat inside the shelter. Another interesting aspect, related to the functioning of the shelters along the a rocky coastline in the coastal areas of the Santa Catarina state, is the inversion of air circulation during day and night. The air, heated during the day flows by natural convection to into the cave through the openings. At the end of the day, the external temperature decreases and the flow reverts. The cold air gets into the shelter and refreshes the environment. During the night, the heat stored at the floor of the cave and at the rocks themselves keep a mild temperature inside the shelter, as can be observed in Figure 4 at 06:00 hours. Part of the heat is transferred out of the shelter, especially from the openings above, which work as natural ventilation and prevent the excessive heating of the shelter. This circulation pattern results in a more efficient utilization of the solar energy. In this case, the solar energy is not only important to the energy flow established by the local food chainweb, but also to the comfort and permanence of the species in the area. The study areas are located on a humid subtropical climate where factors such as air circulation and shadeow are of fundamental importance. The shade ow, provided by the forest,
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Figure 4. Temperature variation inside an otter shelter for September. results on a reduction of the incident energy that enters through the lateral and superior openings. The shape and the internal arrangement of the shelter reflect on the levels of shading. The rocky formation is of great thickness and present has small openings, reducing the solar radiation period inside the shelter, which only occurs mainly around midday. On the coastal areas of Santa Catarina state, which are, dominated by rock formation, the river otter does not built its own environment, but occupies existingent spaces (CARVALHO-JUNIOR, 1990). Such spaces, however, when analyzed comparatively for the 3 environments, appears to show certain patterns which in order to be attractive for the otters. On the other hand, why does the river otter look for spaces in such different environments as the ones here presented? Which environmental factors are acting in order to influencing the animal on its choice? Answers to these questions are of fundamental importance in order to support corrective actions to the conservation of the species. It's important to point out that the frequently observed overlapping of rocks is natural, forming natural galleries and compartments that appear to be important to the animal. The structure created and the disposition of the internal and external spaces were verified for the 3 study areas and appears to be important in determining of the comfort of the animal as, related mainly to temperature and ventilation. How does the otter uses these internal compartments is focus for future research. Figure 5 shows an otter inside a shelter at Lagoa do Peri, taken by an automatic camera with sensor installed on the interior of the shelter. For example, a higher air circulation might help with the epithelial evaporation of the otter, making it feels fresher and more active. During summer, the wind decreases the internal temperature of the shelter through a process of natural crossventilation that is done on a crossed way, through several openings. The fresh air entersy through the lower openings and exits through the upper superior openings. This is a kind of a induced thermal ventilation, in which the rocky material helps to keep the cycle of nocturnal ventilation. The external cold air gets inside while the warmed air exits through the upper openings that work as thermal chimney. It is clear that, the otter conservation along the coastal region of Santa Catarina state depends on the conservation of the Atlantic Rain Forest, currently endangered by human activities. The stratification of the forest, along with the high density of epiphytes represents an important contribution to the formation of safe environments for the otter.
ACKNOWLEDGEMENTS UNIVALI/CTTMar, Estação Ecológica do Piri, Empreendimento Ilha de Porto Belo, Prefeitura Municipal de
Figure 5. Otter inside a shelter at Lagoa do Peri. Photograph taken by automatic camera with sensor. Florianópolis/FLORAM, Reserva Ecológica do Morro dos Macacos. Thanks to Rui Wong for the revision of the text, Deisy, Phillip, Marcelo and Flavia for helping and supporting many field work trips.
LITERATURE CITED BEGE, L. A. DO R., 1996. As aves em Santa Catarina: distribuição, geografia e meio ambiente. Florianópolis, FATMA, 326 p. CARVALHO-JUNIOR, O., 1990. Aspectos da autoecologia de Lutra longicaudis no ecossistema da Lagoa do Peri, SC, Brasil. Tese de Dissertação em Hidroecologia, UFSC Universidade Federal de Santa Catarina, Departamento de Biologia. GABINETE DO PLANEJAMENTO (GAPLAN). 1986. Atlas de Santa Catarina.Aerofoto Cruzeiro, 173p. HARPER, R.J., 1985. Sites of three otters (Lutra lutra) breeding holts in freshwater habitat. Notes from the Mammal Soc., 43: 554-556. JAMESON, R. J. 1989. Moviments, home range, and territory off male sea otters of central california. Marine Mammal Science, 5(2): 159-172 KRUUK, H.; MOORHOUSE, A.; CONROY, J.W.H.; DURBIN, L., and FREARS, S., 1989. An estimate of number and habitat preferences of otters Lutra lutra in Shetland, UK. Biological Conservation, UK, v.49, p.241-254. MELQUIST, W. E. and HORNOCHER, M.G., 1983. Ecology of River, Otters in West Central Idaho. The Wildlife Society, 83:1-60. NICKERSON, R., 1984. Sea Otters - A Natural History and Guide,109p. OLIMPIO, J., 1995. Conservação da fauna de mamíferos silvestres da ilha de Santa Catarina: Aspectos biogeográficos, históricos e sócio-ambientais. Florianópolis: UFSC Universidade Federal de Santa Catarina, Departamento de Biologia, 148p. PARDINI, R.; TRAJANO, E., 1999. Use of shelters by the Neotropical river otter (Lutra longicaudis) in an Atlantic Forest stream, southeastern Brazil. Journal of Mammalogy, v.80, p.600-610. SILVA JUNIOR, J.O. DA., 1988. Considerações preliminares de hábito alimentar da Lutra longicaudis na Lagoa do Peri, Ilha de Santa Catarina, Brasil. Resumos da Reunião Trab. Esp. Mam.Aq. Sul. Montevideo- Uruguai. SCHMIDT, A; TONIOLI, F; PETRULLO, P. and CARVALHO JUNIOR, O. Descrição comparativa de refúgios de Lutra longicaudis para três ambientes distintos. In: SEMANA NACIONAL DE OCEANOGRAFIA, XIII, 2000. Anais XIII Semana Nacional de Oceanografia. 2000. p. 797.
Journal of Coastal Research, Special Issue 39, 2006
