Medium and large sized mammal assemblages in coastal dunes and adjacent marshes in southern Rio Grande do Sul State, Brazil

This paper presents data on species composition and use of habitat of medium and large sized mammal assemblages in a coastal dunes segment and adjacent marshes at Rio Grande municipality, southern Rio Grande do Sul State, Brazil. Records were obtained through visualization of living animals and identification of footprints, feces and remains. From November 2007 to September 2008, nine 600 m long and 5 m wide linear transects were settled on coastal dunes segment (frontal and intermediate dunes) and adjacent marshes, parallel to ocean shore on a 23 km section at Cassino Beach. Transects were settled in areas under high, medium and low levels of anthropic occupancy (A1, A2 and A3, respectively), being three transects on each area. Fourteen species were recorded, distributed in five orders and 10 families. Lepus europaeus was the most frequent species (81.9% of the transect walks), present in all areas and seasons, followed by Lycalopex gimnocercus (23.5%) and Conepatus chinga (10.3%). Five species were present on A1, seven on A2 and fourteen on A3. Seven species were recorded on frontal dunes, nine on intermediate dunes and 13 on adjacent marshes.


Introduction
Mammals (Class Mammalia) comprehend a highly diversified group, being recognized 5,418 species distributed in all of the continents and inhabiting a variety of environments (WILSON;REEDER, 2005).In Brazil there are 688 recorded species and more than 140 occur in the southernmost State of Rio Grande do Sul (REIS et al., 2011a).
Regional mammalian inventories in Rio Grande do Sul State were realized mainly in north and central areas (e.g.CADEMARTORI et al., 2002 and2003;KASPER et al., 2007a and b;MARQUES;RAMOS, 2001;SANTOS et al. 2004 and2008;WALLAUER;ALBUQUERQUE, 1986).Most of these sampled areas, however, are characterized by the dominance of forest formations such as Pluvial, Mixed and Dense Ombrophilous forests.In the southern part of the State, mainly characterized by open formations (VIEIRA, 1983), there is few data on species composition of the mammalian fauna in the distinct environments.The only available data include the observations of Gianuca (1997 and1998) on some species of rodents, carnivores and lagomorphs found in coastal dunes of Cassino Beach, Rio Grande municipality.
Dune ecosystems are considered "extreme biological importance" areas for conservation in Brazilian coast (MMA, 2002).In parallel, an increasing disturbance and mischaracterization of these environments due to tourism, urbanization, cattle grazing and silviculture is observed in southernmost Brazilian coastal plain (GIANUCA, 1997;SEELIGER;COSTA, 1998).Therefore, unguided management and expansion of the urban areas can represent a serious threat for mammalian populations in coastal dune formations in the State.Aiming to contribute for the knowledge and conservation of biodiversity in these systems, herein we present data on species composition, habitat occupancy and abundance of medium and large sized mammals (body mass higher than 1 kg) in areas under distinct levels of human occupancy in a coastal dune stretch and adjacent marshes in southernmost Brazil.

Study area
The municipality of Rio Grande (31°47'02''-32°39'45'' S; 52°03'50'' -52°41'50'' W) is located in southern coastal plain of Rio Grande do Sul State, southern Brazil.It has an area of 2,834 km² and low altimetric levels, between sea level and two meters, except by dune formations, which can reach to seven meters.The climate in the region is classified as Cfa of Köppen, with temperatures varying from 9.5°C in July (minimum average) to 27.2°C (maximum average).The monthly precipitation average is 104 mm and the rainiest months are July, August and September (VIEIRA, 1983).
The study area comprehends a stretch of 23 km in the coastal dune system (frontal and intermediate dunes) and adjacent swamps in Cassino Beach, located between Patos Lagoon discharge channel ("Rio Grande channel") and "Navio Altair" coastal stream (32º18"065" -52º16'057"W".), parallel to the oceanic shore (Figure 1).

Data sampling
Data were obtained from November 2007 to September 2008.Nine 600 m long and 5 m wide linear transects were settled in the sampled stretch, distributed in three distinct subareas classified according to degree of human disturbance, being: A1) area between Patos Lagoon channel and the trade center (32 o 09'342"S -52º06'003"W e 32º10'450"S -52º08'424"W), presenting the highest density of anthropic occupancy, intense vehicles traffic, tourism and recreational activities, intensive cattle grazing and garbage deposition; A2) area in southwards from Aquaculture Marine Station of Federal University of Rio Grande (32º12'192"W -52º10'312"W e 32º14'098"S -52º12'514"W), characterized by a moderate degree of anthropic occupancy, with vehicle traffic, tourism and recreational activities more concentrated in summer months and intensive cattle grazing; A3) area near to "Navio Altair" coastal stream (32º15'595"S -52º14'290"W and 32º18"065" -52º16'057"W"), characterized by the lowest degree of anthropic occupancy, with vehicle traffic, tourism and recreational activities more concentrated in summer months and moderate cattle grazing.
Three transects were settled in each sample subarea (A1, A2 and A3) (Figure 1).Each transects was divided in three parallel 200 m long segments, settled in biotopes of frontal dunes, intermediate dunes and adjacent marsh.Transects were walked twice per year season, totalizing eight samples in each transect.The total walked distance was 43,200 m, equally distributed between year season and subareas.
Each transect repetition was evaluated qualitatively according to the presence and absence of species.The species were recorded by identification of footprints, feces, remains (bones, skins) and visualization of living animals.Transects were walked by a single watcher, at an average speed of 2 km h -1 .All the found remains were moved to avoid recounting.Identification of vestiges and remains were based in author's experience, consults to specialists and field guides of Becker and Dalponte (1999), Borges and Tomás (2004)  Distinction between Dasypus novemcinctus and D. hybridus footprints were based on the size as shown in Becker and Dalponte (1999).Distinction between Leopardus geoffroyi and domestic cat footprints were based in size and morphological differences shown in Oliveira and Cassaro (2005).The recorded species were classified accordingly to Reis et al. (2011a).Chisquare test (χ 2 ) was used to verify if there are significant differences in species richness recorded among subareas (A1, A2 and A3), at a significance level of 5%.

Results
A total of 14 species of medium and large sized mammals (13 native and one exotic) was recorded in the sampled stretch, distributed in five orders and 10 families (Table 1).
In relation to the sampled biotopes, the species L. europaeus, L. gymnocercus, L. longicaudis, M. coypus and D. novemcinctus were recorded in both frontal and intermediate dune and adjacent marsh.Conepatus chinga, G. cuja and H. hydrochaeris were recorded in intermediate dune and adjacent marsh.Procyon cancrivorus was recorded in frontal dune and adjacent marsh while D. albiventris was found in frontal and intermediate dune.
Except for D. albiventris, all the other species were found in adjacent marshes.The highest richness observed in this habitat could be related to the high productivity and food resource availability in these humid systems (SEELIGER, 1998b), when compared to xerophytic features of the dune formations.The habitat generalist species, D. albiventris, however, occurs in palustrine systems such as swamps and reed (ACHAVAL et al., 2007), and may also occur in marshes adjacent to coastal dunes.Importantly, D. hybribus, observed only in marsh areas in the present study, was already found in the dune systems by Gianuca (1997).
In relation to dune biotopes, it was observed a similar richness in frontal and intermediate systems, despite of the differences in species composition.An interesting fact is the footprints of M. coypus and H. hydrochaeris in dune biotopes, at distances greater than 300 m from waterbodies (coastal streams, marshes, pluvial channels).The occurrence of these rodents in dune habitats may be related to the use of psamophile vegetation as a food resource.Nevertheless, these and other ecological aspects of mammal species in the dune system require further researches.
In the present study we verified the presence of L. europaeus, L. gymnocercus, L. crassicaudata, M. coypus and C. chinga in areas under high anthropization degree.Lepus europaeus is native in Europe and it is considered agricultural pest in several countries in South America, presenting a remarkable adaptability and inhabiting both open as forested areas (GRIGERA; RAPOPORT, 1983;JAKSIC et al., 2002;REIS et al., 2011b).In study area, the European hare is commonly hunted with the aid of trained dogs, and despite the constant removal of individuals, vestiges of this species were found in large quantities in all established transects, indicating its high abundance.The possible environmental impacts cause by L. europaeus in dune biotopes are unknown, but it is known that the species assumed the role of competitive face of native herbivores in areas with high population densities (AURICCHIO; OLMOS, 1999).The carnivores L. gymnocercus and C. chinga inhabit mainly the open areas (CHEIDA et al., 2011) and in southern coastal plain were found even in densely urbanized areas (F.M. Quintela, pers.obs.), indicating the high degree of adaptation of these species to modified environments.The didelphid L. crassicaudata and the rodent M. coypus are also commonly found associated with aquatic environments in disturbed areas in the region, being the first recorded using human dwelling as shelter (F.M. Quintela, pers.obs.).Santos et al. ( 2008) also determined the occurrence of L. europaeus, L. crassicaudata, M. coypus, L. gymnocercus and C. chinga in highly modified habitats in Central Depression of Rio Grande do Sul State, being the tree first classified as "constant" in their sampling.
Another relevant aspect is the presence of domestic animals (dogs, cats, pigs, equines and cattle), verified in all sampled areas.According to IUCN (2000), exotic species represent the second major threat to biodiversity.Galetti and Sazima (2006), in an urban Atlantic Forest fragment, evaluated the impact of feral dogs, reporting predation on didelphimorphs, rodents, cingulates, primates and artiodactylas.Feral cats are also considered a grave problem in natural environments, preying on native species and competing with autochthonous species of the same trophic position, beside the fact of pathogen transmission to wild populations (DICKMAN, 1996).
No less concerning are the effects of grazing, also evidenced in all sampled areas.The intensive cattle and horse grazing implies in reduction of vegetal covering responsible dune fixedness, leading to destabilization and loss of function of the habitat (GIANUCA, 1997).Therefore, disturbance and modification of habitat features caused by domestic animals may be affecting the native mammalian in costal dunes and adjacent systems.

Conclusion
In the present study we observed the inverse relationship between species richness and degree of human occupancy, which highlights the impacts of anthropization on medium and large sized mammal assemblages in dune environments and adjacent marshes in southernmost Brazil.This inventory contributes to the knowledge of faunal diversity in subtropical coastal dunes and associated habitats, warning about threats and providing support for conservation measures.

Figure 1 .
Figure 1.Location of Rio Grande do Sul State (A), part of southern Coastal Plain (B) and study area (C (white line), D), being A1, A2 and A3 areas under high, medium and low level of human occupancy, respectively.

Table 1 .
Species and supraespecific categories, subareas, biotopes of encounter and types of records of medium and large sized mammals recorded in a costal dunes segment and adjacent marshes in municipality of Rio Grande, southern Coastal Plain of Rio Grande do Sul State.A1 = area under high level of human occupancy, A2 = area under medium level of human occupancy, A3 = area under low level of human occupancy, DF = frontal dunes, DI = intermediate dunes, MA = adjacent marshes, FO = footprints, FA = faeces, BU = burrows, MU = mucus, SI = sightings, CA = carcass.
Relative frequency of medium and large sized mammal species on 72 transect walks performed in a 23 km stretch of costal dunes and adjacent marshes in municipality of Rio Grande, southern Coastal Plain of Rio Grande do Sul, State.Discussion According to Cáceres et al. (2007), all the species recorded in the present study occur in open areas or have wide distribution.The carnivores L. longicaudis and L. geoffroyi, however, are listed in the "Red List of Threatened Fauna in Rio Grande do Sul, State" Acta Scientiarum.Biological Sciences Maringá, v. 35, n. 1, p. 55-61, Jan.-Mar., 2013