Impact of a natural disaster on the habitat and occurrence of Lontra longicaudis (Mustelidae, Carnivora) in Serra da Prata, Paraná, Brazil

ABSTRACT Studies about natural disasters impact on fauna are rare in the scientific literature. Concerning Lontra longicaudis (Olfers, 1818), published data could not be found. This study aimed to determine whether the landslides occurred in March 2011 in part of the slopes of Serra da Prata (Paraná, Brazil) affected the occurrence of the Neotropical Otter in the impacted area. With this purpose, the study area comprehended an affected river (Rio Santa Cruz - RSC), on the east face of those mountains that was compared to another one, on the same face and with similar original features, but not affected by the natural disaster (Rio das Pombas - RP). The study area is located within the boundaries of a conservation unit (Parque Nacional de Saint-Hilaire/Lange, PNSHL). Seven field campaigns from the altitudinal limit of PNSHL (60 m a.s.l.) towards upstream, were conducted between August 2012 and July 2013. Campaigns consisted of an active search for evidence (scats, footprints, scratches) and otter dens along 3 km of river banks. Other mammal records were also registered. Each evidence was noted down on a field book, photographed and georeferenced. Dens were monitored along field campaigns. Concerning otters, 102 vestiges (11 scratches, 11 footprints and 80 scats) and 17 dens were recorded in the not affected river (RP); and the affected river (RSC) presented only four vestiges (three footprints, one scat) and one den. Other mammal records denoted the presence of eight taxa at RP and 14 at RSC. The conspicuous differences in the amount of evidences of otter presence indicate that the natural disaster affected the otter population in RSC river and that even more than two years later otters had only discreetly come back. On the other hand, other mammal species, such as Cuniculus paca (Linnaeus, 1758) reoccupied the river banks abundantly.

摘要 有关自然灾害对动物群落影响的研究在科学文献中较为稀缺。针对南美大水獭（Lontra longicaudis，Olfers, 1818），目前尚未检索到已发表的相关研究数据。本研究旨在探明2011年3月发生在巴西巴拉那州普拉塔山（Serra da Prata）部分坡体的滑坡事件，是否对受影响区域内的新热带水獭（Neotropical Otter）的种群分布造成了干扰。
为此，本研究选取该山脉东坡受滑坡影响的圣克鲁斯河（Rio Santa Cruz - RSC）作为研究样地，并以同一东坡、原生地貌特征相似但未受此次自然灾害波及的庞巴斯河（Rio das Pombas - RP）作为对照样地。研究区域位于圣伊莱尔-朗热国家公园（Parque Nacional de Saint-Hilaire/Lange, PNSHL）的管辖范围内。
2012年8月至2013年7月期间，研究团队共开展7次野外调查，从该公园的海拔下限（60米海拔）沿河道向上游推进。每次调查沿3公里长的河岸展开，主动搜寻水獭的活动痕迹（粪便、足迹、抓痕）以及水獭巢穴。同时同步记录其他哺乳类动物的出现情况。每一处活动痕迹均录入野外记录本，并进行拍照与地理定位。巢穴在历次野外调查中均得到持续监测。
针对新热带水獭的调查结果显示：未受影响的RP河共记录到102处活动痕迹（其中抓痕11处、足迹11处、粪便80处）以及17个巢穴；而受滑坡影响的RSC河仅记录到4处痕迹（3处足迹、1处粪便）以及1个巢穴。其他哺乳类动物的观测数据表明，RP河区域共记录到8个类群，RSC河区域则记录到14个类群。
水獭活动痕迹数量的显著差异表明，此次自然灾害对RSC河的水獭种群造成了显著负面影响，且即便在灾害发生两年多后，水獭的种群仍仅实现了小幅恢复。反观其他哺乳类动物，如斑豚鼠（Cuniculus paca，Linnaeus, 1758）已大量重新占据河岸区域。