A carregar...
Projeto de investigação
MODELING SPECIES DISTRIBUTIONS ACROSS STREAM NETWORKS USING TIME TO FIRST DETECTION.
Financiador
Autores
Publicações
Combining geostatistical and biotic interaction modelling to predict amphibian refuges under crayfish invasion across dendritic stream networks
Publication . Mota-Ferreira, Mário; Beja, Pedro
Aim: Biological invasions are pervasive in freshwater ecosystems, often causing native
species to contract into areas that remain largely free from invasive species impacts.
Predicting the location of such ecological refuges is challenging, because they
are shaped by the habitat requirements of native and invasive species, their biotic
interactions, and the spatial and temporal invasion patterns. Here, we investigated
the spatial distribution and environmental drivers of refuges from invasion in river
systems, by considering biotic interactions in geostatistical models accounting for
stream network topology. We focused on Mediterranean amphibians negatively impacted
by the invasive crayfishes Procambarus clarkii and Pacifastacus leniusculus.
Location: River Sabor, NE Portugal.
Methods: We surveyed amphibians at 168 200-m stream stretches in 2015.
Geostatistical models were used to relate the probabilities of occurrence of each species
to environmental and biotic variables, while controlling for linear (Euclidean) and
hydrologic spatial dependencies. Biotic interactions were specified using crayfish probabilities
of occurrence extracted from previously developed geostatistical models.
Models were used to map the distribution of potential refuges for the most common
amphibian species, under current conditions and future scenarios of crayfish expansion.
Results: Geostatistical models were produced for eight out of 10 species detected,
of which five species were associated with lower stream orders and only one species
with higher stream orders. Six species showed negative responses to one or
both crayfish species, even after accounting for environmental effects and spatial dependencies.
Most amphibian species were found to retain large expanses of potential
habitat in stream headwaters, but current refuges will likely contract under plausible
scenarios of crayfish expansion.
Main conclusions: Incorporating biotic interactions in geostatistical modelling provides a
practical and relatively simple approach to predict present and future distributions of refuges
from biological invasion in stream networks. Using this approach, our study shows
that stream headwaters are key amphibian refuges under invasion by alien crayfish
Spatial modelling of temporal dynamics in stream fish communities under anthropogenic change
Publication . Mota-Ferreira, Mário; Filipe, Ana Filipa; Magalhães, Maria Filomena; Carona, Sara; Beja, Pedro
Aim: Understanding temporal changes in aquatic communities is essential to address
the freshwater biodiversity crisis. In particular, it is important to understand
the patterns and drivers of spatial variation in local community dynamics, generalizing
temporal trends from discrete locations to entire landscapes that are the main
focus of management. Here, we present a framework for producing spatially continuous
views of community dynamics, focusing on stream fish affected by hydropower
development.
Location: River Sabor, NE Portugal.
Methods: We sampled stream fish at thirty sites between 2012 and 2019. Community
trajectory analysis was used to quantify the directionality and velocity of community
change, and the geometric resemblance of community trajectories between sites.
Geostatistical models for stream networks were used to relate metrics describing
community dynamics to environmental variables, while controlling for Euclidean and
hydrologic spatial dependencies, and to map spatial variation in community dynamics
across the watershed.
Results: Trajectories in multivariate space underlined strong temporal dynamics, with
local communities deviating and returning to previous states, but without evidence for
directional changes. Accordingly, directionality values were low and not consistently affected
by environmental variables. The velocity of community change varied markedly
across the watershed and it was strongly affected by stream order and elevation, with
faster changes observed in lowland streams draining into hydroelectric reservoirs and
with a high proportion of exotic species. Pairwise distances between community trajectories
were strongly related to hydrologic and environmental distances between sites.
Main conclusions: Local stream fish communities were in a loose equilibrium across
the watershed, but they fluctuated at a faster rate closer to a hydroelectric reservoir.
Integrating community trajectory analysis and geostatistical modelling provides a relatively
simple framework to understand how, where and why temporal community
dynamics vary across dendritic stream networks and to visualize spatial patterns of
community change over time in relation to anthropogenic 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/95202/2013