Hydromorphology Meets Mammal Ecology: River Morphological Quality, Recent Channel Adjustments and Otter Resilience

Abstract

The need for a multidisciplinary approach for characterizing water bodies in terms of morphological, chemical and ecological quality has hastened the growth of hydromorphology as a cross-disciplinary topic at the interface of hydrology, geomorphology and ecology. Many authors have analysed how hydroecology may affect freshwater biodiversity, although little is known about how this biodiversity might be affected by river morphological quality. We examined how well the presence of the semi-aquatic Eurasian otter can be predicted by the rivers' morphological quality and its adjustments over the last decades. We tested the morphological quality index (MQI) methodology in 38 reaches of five rivers in southern Italy, 23 of which were positive to otter presence. In each reach, we examined 28 indicators contributing to the MQI and its 11 sub-indices. The results showed a significant relationship between the probability of the presence of otters, MQI, and some sub-indices. The best performing sub-indices were related to channel adjustments and the continuity of river processes. A more detailed analysis of channel adjustments showed a detrimental effect of channel incision (>3 m) and a positive effect of narrowing, particularly where it occurred simultaneously with the development of forest in the new floodplain. The continuity of river processes has driven the migration of river banks and the development of ponds and secondary channels, likely increasing the availability of dens and resting sites and the hunting capabilities of otters. Our results stressed the importance of fluvial dynamics and sustainable adaptive river management for the habitat quality of semi-aquatic species. Figure 1. (A) Basins within the current otter range in Italy. (B) Details of the study area, physiographic units (Table I), and segments. (C) River reaches analysed. The last letter of the identification code indicates the river (T = Trigno, B = Biferno, Va = Vandra, V = Volturno, C = Calore) RIVER QUALITY AND OTTERS 269 Figure 5. Example of channels turned into terraces or floodplains that were colonized by farming or riparian vegetation in the Volturno (A = 1954; B = 2007), Biferno (C = 1954; D = 2007) and Trigno (E = 1954; F = 1998) rivers. Dashed line is the boundary of the active channel in 1954 RIVER QUALITY AND OTTERS

Mapping riparian habitat using a combination ofremote-sensing techniques

“…In this study, the selected target species were the Eurasian otter (Lutra lutra) and water deer (Hydropotes inermis). The otter is a flagship threatened species, and is also one of the key species in riparian ecosystems (Stevens, Organ, and Serfass 2011;Scorpio et al 2014); their range covers most of Europe and Asia and can be a useful indicator for the evaluation of ecological disturbances or for conservation planning (Soulé and Terborgh 1999). White, McClean, and Woodroffe (2003) showed that habitat types associated with spraints and not the density and height of vegetation affect the otter's habitat characteristics.…”

The diet of otters (Lutra lutra) on the Agri river system, one of the most important presence sites in Italy: a molecular approach

“…At present, the Southern-Italian population, geographically and genetically isolated from all otter populations living in Europe (Spagnesi, 2002;Randi et al, 2003), occurs in a continuous range from Abruzzo to Basilicata, Calabria and Apulia (Giovacchini et al, 2018). Despite a general positive trend and a slow recovery with an expansion northward (Fusillo, Marcelli & Boitani, 2003;De Castro & Loy, 2007;Prigioni, Balestrieri & Remonti, 2007;Balestrieri et al, 2008;Loy et al, 2009;Buglione et al, in press), the otter in Italy is one of the most threatened mammals, listed as Endangered (EN, category D) on the Official Italian Red List (Loy et al, 2010;Rondinini et al, 2013;Scorpio et al, 2014), both at national and local levels.…”

Spatial genetic structure in the Eurasian otter (Lutra lutra) meta-population from its core range in Italy

“…The Eurasian otter (Lutra lutra, Linnaeus 1758) has suffered a marked decline in many European countries during the second half of the twentieth century, due to the combination of global and local factors, such as human persecution, pollution, and habitat fragmentation (Mason, 1995;Murk et al, 1998;Conroy & Chanin, 2000;Mason & Wren, 2001;Ruiz-Olmo et al, 2002;Panzacchi et al, 2011;Scorpio et al, 2016).…”