A carregar...
Projeto de investigação
Impacts of freshwater invasive crayfish species on key ecosystem processes under a climate change scenario
Financiador
Autores
Publicações
Combined per‐capita and abundance effects of an invasive species on native invertebrate diversity and a key ecosystem process
Publication . Carvalho, Francisco; Pascoal, Cláudia; Cassio, Fernanda; Teixeira, Amílcar; Sousa, Ronaldo
1. Invasive alien species (IAS) are leading to the homogenisation of taxonomic
and functional biodiversity, with negative consequences for key ecosystem
processes in fresh water. Invasive signal crayfish (Pacifastacus leniusculus) is expected
to disrupt detritus-based
food webs by affecting leaf breakdown and/or
by decreasing invertebrate density and diversity through predation. The combination
of per-capita
and abundance effects of P. leniusculus in invaded ecosystems
is still largely unknown.
2. A four-week
field experiment was established in Rabaçal and Tuela Rivers (NE
Portugal) to assess effects of P. leniusculus on invertebrate taxonomic and functional
diversity and leaf litter breakdown following a gradient of invasion. We
controlled the presence and absence of crayfish by placing the animals and leaf
litter inside cages at six sites (three sites per river) according to the crayfish in
situ abundance (absent, low, high). Cages were covered with coarse-or
fine-mesh
net to allow or prevent invertebrates from accessing the leaves.
3. Results showed that higher crayfish in situ abundance led to a decrease in abundance,
richness and Shannon diversity of invertebrates and to changes in the
communities’ structures. Higher crayfish abundance led also to a decrease in invertebrate
functional redundancy and an increase in the percentage of invertebrate
taxa with resistance forms. Leaf litter breakdown increased with crayfish
presence and decreased at sites with higher crayfish abundance.
4. Overall, signal crayfish changed the community structure of invertebrates, with
potential severe long-term
effects on native communities and leaf litter breakdown.
Given the widespread distribution of signal crayfish (and other crayfish
species), their ecological impacts should be assessed carefully, especially in pristine
freshwater ecosystems such as those described here.
Interspecific differences in the physiological condition of native freshwater mussels in response to the invasive Asian clam Corbicula fluminea
Publication . Modesto, Vanessa; Ilarri, Martina; Castro, Paulo S.; Carvalho, Francisco; Cavalheri, Thais; Lopes-Lima, Manuel; Teixeira, Amílcar; Ozório, Rodrigo O.A.; Antunes, Carlos; Sousa, Ronaldo
The Asian clam Corbicula fluminea has been widely introduced into aquatic ecosystems and may impact the physiological condition and survival of native freshwater mussels. However, very few studies have evaluated this issue quantitatively. To fill this gap, manipulative field experiments were performed to assess two possible mechanisms of impact on native mussels: (i) interspecific interactions, and (ii) C. fluminea die-offs. We assessed these effects by measuring the physiological condition through the analysis of glycogen content in the foot tissue of the native freshwater mussel species Anodonta anatina, Potomida littoralis, and Unio delphinus. Although with interspecific differences, our results suggest that C. fluminea can impact the physiological condition of native freshwater mussels. Anodonta anatina showed positive significant variations on glycogen content when subjected to high densities of live C. fluminea in contrast to the other native species studied, P. littoralis and U. delphinus, where no significances were observed. On the other hand, these native species do not seem be significantly impacted by the decomposition of C. fluminea resulting from a die-off. Overall, and contrary to our expectations, both experiments showed a positive (or no) effect of C. fluminea on the physiological condition of the three freshwater mussel species.
Invasive dynamics of the signal crayfish Pacifastacus leniusculus in a protected area
Publication . Carvalho, Francisco; Alves, Henrique; Pascoal, Cláudia; Castro, Paulo; Miranda, Fernando Jorge Veloso; Teixeira, Amílcar; Cássio, Fernanda; Sousa, Ronaldo
Invasive species have been drivers of
biodiversity loss and functional changes in aquatic
ecosystems, including in protected areas. Therefore,
monitoring population invasion dynamics and biological
traits is fundamental to better understand their
ecological and economic impacts and for management
actions development. We followed signal crayfish
(Pacifastacus leniusculus) invasion in Rabaçal
River upper reach at Montesinho Natural Park, Portugal. We collected information on the spread
and biological traits (abundance, size, weight, physical
condition, sex ratio, and aggressiveness) to assess
differences between invasion core and front areas and
among years. Signal crayfish population remained
restricted since first reports in 2013 in the invasion
core until 2017. After 2019, signal crayfish population
has been spreading downstream, decreasing
abundance at invasion core but increasing at invasion
front. Significant higher number of crayfish with claw
loss indicate potential higher signs of aggressiveness
in the invasion front. Results also demonstrate a
significant dominance of females although sex ratio
is closer to 1:1 at the invasion front. Overall, results
indicate signal crayfish is spreading and increasing
their abundance at Rabaçal River highlighting the
need for immediate management actions to hold dispersion
and mitigate possible impacts.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Número da atribuição
SFRH/BD/119957/2016