The reintroduction of a plant species regionally extinct in the wild poses a stimulating conservation challenge. However, when the issue concerns an aquatic dioecious macrophyte, with vigorous asexual reproduction forming very dense floating mats that can alter aquatic communities (through competition and allelopathy), each step must be very well planned. This is the case of Stratiotes aloides L. (water soldier), a keystone species that is declining in Europe, but is recognized as invasive in North America. The species, once abundant in the wetlands of North-Eastern Italy, is currently extinct in the wild in Italy. Only female Italian plants have been saved from extinction and are cultivated ex situ. To assess the feasibility of the de-extinction of Stratiotes aloides in Italy we investigated the water quality, the genetic diversity, and the potential spread of the species in its European range. The high concentrations of surface water inorganic nitrogen (especially nitrates) were identified as the likely cause of decline and extinction of S. aloides. The analyses of genetic diversity revealed the presence of different genetic patterns across Eurasia, that could be explained through long-distance bird-mediated dispersal events. Moreover, chromosome counts revealed the presence of diploid (2n =24) and tetraploid (2n =48) populations. According to our results the reintroduction of vital populations of Stratiotes aloides in Italy could be carried out using male individuals from the same genetic cluster of the Italian females, to avoid outbreeding depression. High-density stands must be reintroduced to permit self-facilitation of S. aloides under high nitrogen loads. However, considering the presence of high nitrogen loads in historical growing sites of S. aloides, there is a high risk of failure. Though in case of successful reintroduction, the risk to spread vegetatively downstream and the long-distance bird-mediated dispersal of seeds with unknown consequences on already threatened freshwater ecosystems cannot be ruled out. Therefore, considering the risks and benefits of the de-extinction of Stratiotes aloides, chaperoned managed relocation of female individuals in isolated water bodies basin (like gravel pits) could be the best solution.

Challenges and risks of conservation of an aquatic macrophyte extinct in the wild / S. Orsenigo, I. Vagge, G. Rossi, A.J. Smolders, T. Abeli. ((Intervento presentato al 19. convegno International Botanical Congress (IBC) tenutosi a Shenzhen, China nel 2017.

Challenges and risks of conservation of an aquatic macrophyte extinct in the wild

S. Orsenigo;I. Vagge;
2017

Abstract

The reintroduction of a plant species regionally extinct in the wild poses a stimulating conservation challenge. However, when the issue concerns an aquatic dioecious macrophyte, with vigorous asexual reproduction forming very dense floating mats that can alter aquatic communities (through competition and allelopathy), each step must be very well planned. This is the case of Stratiotes aloides L. (water soldier), a keystone species that is declining in Europe, but is recognized as invasive in North America. The species, once abundant in the wetlands of North-Eastern Italy, is currently extinct in the wild in Italy. Only female Italian plants have been saved from extinction and are cultivated ex situ. To assess the feasibility of the de-extinction of Stratiotes aloides in Italy we investigated the water quality, the genetic diversity, and the potential spread of the species in its European range. The high concentrations of surface water inorganic nitrogen (especially nitrates) were identified as the likely cause of decline and extinction of S. aloides. The analyses of genetic diversity revealed the presence of different genetic patterns across Eurasia, that could be explained through long-distance bird-mediated dispersal events. Moreover, chromosome counts revealed the presence of diploid (2n =24) and tetraploid (2n =48) populations. According to our results the reintroduction of vital populations of Stratiotes aloides in Italy could be carried out using male individuals from the same genetic cluster of the Italian females, to avoid outbreeding depression. High-density stands must be reintroduced to permit self-facilitation of S. aloides under high nitrogen loads. However, considering the presence of high nitrogen loads in historical growing sites of S. aloides, there is a high risk of failure. Though in case of successful reintroduction, the risk to spread vegetatively downstream and the long-distance bird-mediated dispersal of seeds with unknown consequences on already threatened freshwater ecosystems cannot be ruled out. Therefore, considering the risks and benefits of the de-extinction of Stratiotes aloides, chaperoned managed relocation of female individuals in isolated water bodies basin (like gravel pits) could be the best solution.
lug-2017
Settore BIO/03 - Botanica Ambientale e Applicata
Challenges and risks of conservation of an aquatic macrophyte extinct in the wild / S. Orsenigo, I. Vagge, G. Rossi, A.J. Smolders, T. Abeli. ((Intervento presentato al 19. convegno International Botanical Congress (IBC) tenutosi a Shenzhen, China nel 2017.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/523935
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