IMPACT - Developing an integrated model to predict abiotic habitat conditions and biota of rivers for application in climate change research and water management

Funder

Organizational Unit

Publications

Biological variation in temporary streams: understanding river patches at different scales for monitoring and management applications

Publication . Sroczynska, Katarzyna Krystyna; Chícharo, Luís; Wojtal-Frankiewicz, Adriana

Biota and ecological processes are highly complex and vary at every scale. This underscores the importance of employing a multi-scale design to adequately understand these processes and complex relationships in riverine ecosystems. In addition, there is a strong need to develop appropriately scaled indicators of river ecosystem health that include this biotic complexity in a manageable fashion. Unfortunately, currently available indicators are either too complex or do not adequately capture the highly variable changes to the ecosystem. Patches are good templates for various ecological processes and because they are considered to be stable over the spatial and temporal scales, they can be used as functional filters of important processes in streams. The aim of this thesis is to employ patch theory and multi-scale approach to develop structural and functional indicators of the ecosystem health at the patch level and evaluate in which of the scales these indicators are of the highest relevance for the patch. The system at which these indicators were tested consists of headwater intermittent streams within a Mediterranean catchment. Three scales were considered: reach scale, stream scale and catchment scale. According to the results patch as a source of variation was not well explained by the structural measures of benthic communities at catchment scale. This was related to the effect of occurrence of a strong environmental filter (mainly altitude and its association with conductivity and temperature), which limited distribution of biota and constrained the occurrences of certain species at the smaller scales. Also, these filters were demonstrated to act indirectly through patterns in habitat formation and availability. Patch investigated at the reach scale provided slightly more predictable unit of species organization, nonetheless, still benthic communities of some of the patch types overlapped. Instead, the most consistent measures of ecosystem health that could be applied to studying patches were the metabolism measurements at the reach scale and the isotopic signatures at the stream scale. Next step forward would be to establish reference values for these two approaches for undisturbed systems, and subsequently to incorporate these measures into biomonitoring guidelines. Following disturbance, patches have been shown to be the most appropriate unit used when evaluating biotic recovery. As such, this study represents an important step towards development of better biomonitoring tools as well as evaluation of the restoration effort.

2017-12-18Doctoral thesis

Open access

Indicator macroinvertebrate species in a temporary Mediterranean river: recognition of patterns in binary assemblage data with a Kohonen artificial neural network

Publication . Sroczyńska, Katarzyna; Claro, M.; Kruk, A.; Wojtal-Frankiewicz, A.; Range, P.; Chicharo, Luis

Current classifications used in bioassessment programs, as defined by the Water Framework Directive (WFD), do not sufficiently capture the variability present in temporary Mediterranean streams. This may result in inaccurate evaluation of the water quality biological metrics and difficulties in setting reference conditions. The aim of the study was to examine if aquatic invertebrate data of increased taxonomical resolution but expressed on a binary abundance (frequent/rare) scale and referring to good bioindicator species only suffice to indicate clear gradients in water courses with high natural variability such as intermittent Mediterranean streams. Invertebrate samples were collected from 74 sites in the Quarteira River basin, located in southern Portugal. Their classification with the use of a Kohonen artificial neural network (i.e., self-organising map, SOM) resulted in five categories. The variables that drove this categorization were primarily altitude, temperature and conductivity, but also type of substrate, riparian cover and percentage of riffles present. According to the indicator species analysis (ISA), almost all the studied taxa were significantly associated with certain SOM categories except for the category that included sites with disrupted flow regime. The SOM and ISA allowed us to effectively recognize biotic and abiotic patterns. Combined application of both methods may thus greatly enhance the effectiveness and precision of biological surveillance and establish reference sites for specific channel units in streams with high natural variability such as intermittent Mediterranean streams. (C) 2016 Elsevier Ltd. All rights reserved.

2017-02Journal article

Restricted access