Research
Postdoctoral project (2014-2017).Plan I2C Xunta de Galicia
Trophic networks of forested headwater streams. Ecosystem responses to global change
The overarching aim of this project is to generate empirical data to understand how trophic interactions affect community dynamics and ecosystem functioning along an increasing gradient of degradation. This research will allow us to look for stoichiometric imbalances that could generate constraints on some structural component and potentially alter ecosystem functioning, and to estimate tolerances and sensitivities of different ecological components of forested headwater ecosystems.
Because isotopic signature of an animal reflects its assimilated diet (DeNiro and Epstein 1978, 1981), SIA analysis has been chosen as a useful tool to estimate the trophic status of consumers in food webs and to quantify the proportion of different food sources in animal diets (Peterson and Fry 1987). This tool will be used within this project to understand which are the main factors influencing food web structure and how it varies along a degradation gradient.
This fact will be achieved through:
1) Field sampling (fall and spring): by taking samples representing all the potential food web components (water, seston, FPOM, periphyton, invertebrates and fish) in 10 streams differing on water nutrients
2) Field experiment: by creating an enrichment gradient in experimental stream channels and analyzing the responses of the periphyton, leaf decomposition and invertebrate colinization.
REFRESH project (2012-2014)
As soon as I came back to Spain from the "Iceland" experience, I started to work on the REFRESH project. Building on a previous EU FP6 Project, Euro-limpacs, REFRESH is concerned with generating the scientific understanding that enables such measures to be implemented successfully. The key objective of REFRESH was to develop a framework that will enable water managers to design cost-effective restoration programmes for freshwater ecosystems, accounting for the expected future impacts of climate change and land-use. The focus was on three principal climate-related and interacting pressures; i) increasing temperature; ii) changes in water levels and flow regimes; and ii) excess nutrients.
In Galicia (NW Spain), we used a controlled field-experimental design to evaluate short-term stream community responses to induced flow reductions in two lowland streams differing in nutrient concentration (i.e. nutrient-poor vs. nutrient-rich). This research has a creative mesocosm-approach and it is relevant because there is a need to have a comprehensive understanding of disturbances to develop and implement effective restoration measures to cope with the impacts of global climate change.
Iceland (3-months stay: February-April 2012)
After finishing my PhD, I have the opportunity to get an university outreach grant, which provides funding to support students to work abroad for up to 3 months. It has brought me to Iceland to do some stream ecology alongside an international team of ecologists studying streams in the Hengill region of Iceland and explore this beautiful country.
The research focused on understanding the effects of global warming on stream food webs and ecosystem processes, and I helped them in different tasks, mainly related to field sampling. I am very happy with the experience, even although it was the worst weather in which I have ever worked!
Water Framework Directive in Balearic Islands (2005-2009)
The Water Framework Directive (WFD) has encouraged the development of classification systems to assess the ecological status in permanent rivers and streams, but in temporary streams development has been scarce. During these projects, we constructed an invertebrate multimetric index (INVMIB) and a diatom multimetric index (DIATMIB) to assess the ecological status of temporary streams in Mediterranean Islands following the WFD guidance and based on benthic invertebrates and diatom assemblages, respectively.
We studied 60 temporary streams in different seasons (n = 270 samples), corresponding to three different stream types that were a priori established using topographical and valley information: lowland, canyon and mountain streams. Indeed, the classification system obtained with the these multimetrics reflected the ecological quality of temporary streams of the Balearic Islands, and they are considered a valid and accurate tool for the assessment of temporary Mediterranean streams, being currently used by the water authorities of the Balearic Islands.
Water Framework Directive in Galicia (2002-2004)
The degradation of freshwater ecosystems has been a cause of concern for several decades. The implementation of the European Water Framework Directive (WFD; European Union, 2000) has encouraged different applied ecological studies to understand the impact caused to freshwater ecosystems by anthropogenic pressures. The WFD requires that ecological status assessments of rivers and lakes are based on evaluations of phytoplankton, macrophytes and phytobenthos, benthic invertebrates and fish.
During this work, we sampled a total of 72 small and medium rivers from 27 river basins in Coastal Galicia. Sampling was conducted in two seasons: summer 2002–2003 and spring 2004, giving a total of 144 sampling sites. These sites included minimally disturbed sites, defined as reference sites, and impacted sites which were influenced by different human pressures. We used the invertebrate and diatom assemblages to calculate multimetric indices to evaluate the water quality in coastal Galician rivers.
Detritivore pathways of forested headwater streams. The role of a dominant species in the ecosystem
My thesis focused on the study of the structure and functioning of small forested streams under temperate climates. In particular, it was focused on detrital energy pathways in stream ecosystems, and the effects of temperature and food quality on detritivore life history. This thesis was performed through in-stream experiments in Galicia (NW Spain) and in the Malcolm Knapp Research Forest in the British Columbia (SW Canada), as well as with laboratory experiments carried out at the Department of Ecology and Animal Biology of the University of Vigo.
Since forested headwater streams are strongly dependent on the allochthonous inputs of organic matter from the riparian vegetation (i.e., stream-riparian linkage), I tried to elucidate resource-consumer relationships by relating leaf packs dynamics with their associated invertebrate community. In all the studies included in the thesis, I stressed the importance of preserving natural riparian-stream environments (tree native species, riparian shaded corridors) to maintain the natural functioning of these detritus-based streams.
The present thesis consists of an Introduction that brings us closer to the world of the ecology of headwater streams by describing the main components of these ecosystems (i.e., habitat, resources and consumers), and highlights those factors that have the potential to control them. Each Main Section includes all the specific research carried out, separated in individual chapters, which have been structured as scientific papers (already published or accepted for publication in different journals, see my CV).