Biology subjects

Peixoto, S.

Publications and source records attributed to Peixoto, S..

3 recordsLinked to original sources

bioRxiv2025

Herbivore pressure modulates soil multifunctionality in a Mediterranean landscape

Ongoing global environmental changes demand cost-effective strategies to restore ecosystem functioning. Within this context, the reintroduction of large mammalian herbivores has emerged as a promising approach to recover ecological processes and foster self-sustaining, biodiverse ecosystems. However, the impacts of such initiatives remain poorly understood, particularly regarding their effects on soil functions and ecological processes. We tested whether large herbivore densities (wild horses (Garrano breed) and cattle (Maronesa breed, an ancient lineage close to aurochs) modulates soil multifunctionality (the simultaneous provision of multiple ecosystem functions) across habitats (grasslands, shrublands, and forests) and seasons (fall and spring) in a Mediterranean landscape. Using composite multivariate indices describing soil functions related to biogeochemical cycles (i.e., enzymatic activities) and physicochemical properties (pH, conductivity, organic matter, and nutrient loads), we found that soil enzymatic activities varied seasonally, being higher in spring, and interacted with habitat and herbivore pressure gradients. Habitat and herbivore pressure explained the variation in soil multifunctionality during spring, while in fall it was mainly driven by herbivore pressure. Enzymatic stoichiometry, particularly C:P ratios, strongly predicted soil fertility and multifunctionality, showing positive relationships in forest habitats and under herbivore pressure. A mechanistic approach confirmed that herbivore impacts on soil functioning operated primarily through changes in soil properties and nutrient cycling rather than direct effects. Mediterranean landscapes are rapidly changing, and our results highlight herbivore management as a key tool to sustain soil ecological processes under the rewilding framework. Highlights- Large herbivores impacted soil functions and properties in different habitats - Large herbivores significantly impacted soil nutrient cycling and multifunctionality. - The magnitude of the effects was dependent on season and habitat - Large herbivores indirectly impact soil ecosystem multifunctionality through changes in soil properties.

ecology↗

bioRxiv2024

Proving a negative; estimating species 'Confidence in Absence for Decision-Making' (CIADM) using environmental DNA monitoring

O_LIPolicy-driven decision-making is an important aspect of environmental management globally, often focused on protecting priority species. However, declining trends in freshwater biodiversity have resulted in a lack of up-to-date knowledge regarding the distribution of rare and elusive species. Furthermore, when dealing with priority species, it is sometimes more important to provide a confident assessment of absence, than merely confirm their presence. Without such confident assessments, resource intensive management plans may be misplaced, and not adequately targeted to conserve important remaining populations. C_LIO_LIHere, we present a framework to estimate confidence in absence, referred to as "Confidence in Absence for Decision-Making" (CIADM), based on single-visit environmental DNA metabarcoding data obtained from water samples. It uses a case study of European eel presence / absence upstream of 44 water pumping stations, given their critically endangered status and the legislative drivers for remediation (EC Eel Regulation 1100/2007, Eels (England and Wales) Regulation 2009). Through a high degree of biological (sample) and technical (PCR) replication, we retrospectively assigned confidence in absence values and proposed various strategies to achieve the required confidence levels in future surveys. C_LIO_LIOur findings indicate that 17 out of 44 pumping stations tested positive for eel, and we were able to assign a >99% confidence level that the remaining 27 sites were negative for eel DNA at the time of sampling. Increasing both biological and technical replication increased confidence in absence values. For example, using three PCR replicates per sample, required four replicate biological samples to achieve >95% and six to achieve >99% confidence in eel absence given non-detection. However, we estimate that by using seven PCR replicates per sample a >99% confidence in eel absence following non-detection could be achieved with only three replicate biological samples. Furthermore, we found that eel positive sites had significantly higher species richness, and fish communities differed between eel positive and eel negative sites. C_LIO_LIThis study highlights the importance of optimising workflow specific replication, and provides an adaptable framework to produce confidence estimations of priority species absence given non-detection. C_LI

ecology↗

bioRxiv2023

Mussels on the move: new records of the invasive non-native quagga mussel (Dreissena rostriformis bugensis) in Great Britain using eDNA and a new probe-based qPCR assay

Invasive non-native species (INNS) pose a worldwide environmental threat, negatively impacting invaded ecosystems on an ecological and economical scale. In recent decades, quagga mussels (Dreissena rostriformis bugensis) have successfully invaded several countries in Western Europe from the Ponto-Caspian region, being recorded for the first time in Great Britain (GB) in 2014, in Wraysbury, near London. In recent years, environmental DNA (eDNA) analysis has proven to be a sensitive and effective method for early detection and monitoring of a number of INNS. Previously, a dye-based quantitative PCR (qPCR) assay was developed for the detection of quagga mussels from eDNA samples. Here, a target-specific probe was designed to further increase the specificity of this assay and used to obtain an updated distribution of this species in GB. Twenty-four sites were sampled, including sites with established populations near London and sites spread across the East Midlands and East Anglia regions. Positive detections were obtained for 11 of the 24 sites, and these were widely spread, as far as Nottingham (East Midlands) and Norfolk (East Anglia). Detection rates were 100% at the three sites with known established populations, while rates were lower (3-50% of positive replicates) in the eight newly-identified sites, consistent with an early stage of invasion. Of particular concern was the detection of quagga mussels in major waterways and in popular recreational sites, highlighting urgent measures are needed to control pathways and spread. Our study demonstrates that quagga mussels are considerably more widespread in GB than previously thought and provides a much-needed step towards operational use of eDNA for monitoring quagga mussels.

ecology↗