Margarita Fernández-Aláez

Bio: Margarita Fernández-Aláez is an academic researcher from University of León. The author has contributed to research in topics: Macrophyte & Species richness. The author has an hindex of 21, co-authored 49 publications receiving 1639 citations.

The determination of ecological status in shallow lakes - a tested system (ECOFRAME) for implementation of the European Water Framework Directive

Abstract: 1. The European Water Framework Directive requires the determination of ecological status in European fresh and saline waters. This is to be through the establishment of a typology of surface water bodies, the determination of reference (high status) conditions in each element (ecotype) of the typology and of lower grades of status (good, moderate, poor and bad) for each ecotype. It then requires classification of the status of the water bodies and their restoration to at least 'good status' in a specified period. 2. Though there are many methods for assessing water quality, none has the scope of that defined in the Directive. The provisions of the Directive require a wide range of variables to be measured and give only general guidance as to how systems of classification should be established. This raises issues of comparability across States and of the costs of making the determinations. 3. Using expert workshops and subsequent field testing, a practicable pan-European typology and classification system has been developed for shallow lakes, which can easily be extended to all lakes. It is parsimonious in its choice of determinands, but based on current limnological understanding and therefore as cost-effective as possible. 4. A core typology is described, which can be expanded easily in particular States to meet local conditions. The core includes 48 ecotypes across the entire European climate gradient and incorporates climate, lake area, geology of the catchment and conductivity. 5. The classification system is founded on a liberal interpretation of Annexes in the Directive and uses variables that are inexpensive to measure and ecologically relevant. The need for taxonomic expertise is minimized. 6. The scheme has been through eight iterations, two of which were tested in the field on tranches of 66 lakes. The final version, Version 8, is offered for operational testing and further refinement by statutory authorities.

Loss of diversity and degradation of wetlands as a result of introducing exotic crayfish

Abstract: The introduction of the alocthonous Louisiana red swamp crayfish (Procambarus clarkii) in Chozas (a small shallow lake situated in Leon (North-West Spain)) in 1996 switched the clear water conditions that harboured an abundant and a quite high richness of plants, invertebrates, amphibians and birds to a turbid one followed by strong losses in abundance and richness in the aforementioned groups. Crayfish exclusion experiments done in Chozas previous to this work confirmed the role of crayfish herbivorism on macrophyte destruction that had a trophic cascade effect on the wetland ecosystem. Direct and indirect effects of crayfish introduction on Chozas lake communities have been evaluated and compared with previous conditions before 1996 or with other related lakes in which crayfish were no present. Crayfish had a main role in submerged plant destruction and a potential effect on amphibia and macroinvertebrate population decrease. Plant destruction (99 % plant coverage reduction) was directly related to invertebrates (71 % losses in macroinvertebrate genera), amphibia (83 % reductions in species), and waterfowls (52 % reduction). Plant-eating birds were negatively affected (75 % losses in ducks species); nevertheless, fish and crayfish eating birds increased their presence since the introduction. Introduction of crayfish in shallow plant-dominated lakes in Spain is a main risk for richness maintenance in these endangered ecosystems.

Continental-scale patterns of nutrient and fish effects on shallow lakes: synthesis of a pan-European mesocosm experiment

Abstract: 1. Results are analysed from 11 experiments in which effects of fish addition and nutrient loading on shallow lakes were studied in mesocosms. The experiments, five in 1998, six in 1999, were carried out in six lakes, distributed from Finland to southern Spain, according to a standard protocol. 2. Effects of the treatments on 29 standard chemical, phytoplankton and zooplankton variables are examined to assess the relative importance of bottom-up (nutrient enrichment) and top-down (fish predation) effects. For each year, the experiments in different locations are treated as replicates in a meta-analysis. Results of individual experiments are then compared in terms of the patterns of significant influences of nutrient addition and fish predation with these overall results (the baseline), and between years in the same location. 3. The overall meta-analysis gave consistent results across the 2 years, with nutrient loading influencing all of the chemical variables, and on average 31% of primary producer and 39% of zooplankton variables. In contrast, fish influenced none of the chemical variables, 11% of the primary producer and 44% of the zooplankton variables. Nutrient effects on the system were thus about three times greater than fish effects, although fish effects were not inconsiderable. 4. The relative importance of nutrients and fish in individual experiments often differed between years at the same location and effects deviated to varying degrees from the baseline. These deviations were treated as measures of consistency (predictability) of conclusions in repeat experiments. Consistency increased southwards and this is interpreted as a consequence of more variable annual weather northwards. 5. The influence of nutrient loading was greater southwards and this was probably manifested through naturally greater annual macrophyte abundance in warmer locations in consequence of the longer plant growing-season. There was no trend in the relative importance of fish effects with latitude but this may partly be an artefact of the simple fish community used. These findings suggest that nutrient control should be a greater priority than biomanipulation in the restoration of eutrophicated shallow lakes in warm temperate regions. 6. Starting conditions affected the outcome of experiments. High initial concentrations of total phosphorus and planktonic chlorophyll a concentration (created by local conditions prior to the experiment) led to de-emphasis of the importance of nutrient loading in the experiment.

Shift from clear to turbid phase in Lake Chozas (NW Spain) due to the introduction of American red swamp crayfish ( Procambarus clarkii )

Abstract: Lake Chozas (Leon, NW Spain) until 1997 was a mesotrophic, macrophyte-dominated clear-water lake. The American red swamp crayfish (Procambarus clarkiiGirard) was introduced in 1995–96. In 1998, it increased its numbers coinciding with reductions in plant density from 97% to less than 10% surface cover. The removal of submerged vegetation was accompanied by a fast switch from clear to turbid, Microcystis-dominated conditions in the lake. In situ experiments in Lake Chozas using exclosures and enclosures have proved that the red crayfish are efficient predators of macrophytes. This work gives new evidence of the direct relationship between red-crayfish introduction and the shift from clear to turbid conditions in shallow lakes.

Response of zooplankton to nutrient enrichment and fish in shallow lakes: a pan-European mesocosm experiment

Abstract: SUMMARY 1. Responses of zooplankton to nutrient enrichment and fish predation were studied in 1998 and 1999 by carrying out parallel mesocosm experiments in six lakes across Europe. 2. Zooplankton community structure, biomass and responses to nutrient and fish manipulation showed geographical and year-to-year differences. Fish had a greater influence than nutrients in regulating zooplankton biomass and especially the relative abundances of different functional groups of zooplankton. When fish reduced the biomass of large crustaceans, there was a complementary increase in the biomasses of smaller crustacean species and rotifers. 3. High abundance of submerged macrophytes provided refuge for zooplankton against fish predation but this refuge effect differed notably in magnitude among sites. 4. Large crustacean grazers (Daphnia, Diaphanosoma, Sida and Simocephalus) were crucial in controlling algal biomass, while smaller crustacean grazers and rotifers were of minor importance. Large grazers were able to control phytoplankton biomass even under hypereutrophic conditions (up to 1600 l gT P L )1 ) when grazer biomass was high (>80– 90 lg dry mass L )1 ) or accounted for >30% of the grazer community. 5. The littoral zooplankton community was less resistant to change following nutrient enrichment in southern Spain, at high temperatures (close to 30 � C), than at lower temperatures (17–23 � C) characterising the other sites. This lower resistance was because of a greater importance of nutrients than zooplankton in controlling algal biomass. 6. Apart from the reduced role of large crustacean grazers at the lowest latitude, no consistent geographical patterns were observed in the responses of zooplankton communities to nutrient and fish manipulation.

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

A review of the potential impacts of climate change on surface water quality

Abstract: It is now accepted that some human-induced climate change is unavoidable. Potential impacts on water supply have received much attention, but relatively little is known about the concomitant changes in water quality. Projected changes in air temperature and rainfall could affect river flows and, hence, the mobility and dilution of contaminants. Increased water temperatures will affect chemical reaction kinetics and, combined with deteriorations in quality, freshwater ecological status. With increased flows there will be changes in stream power and, hence, sediment loads with the potential to alter the morphology of rivers and the transfer of sediments to lakes, thereby impacting freshwater habitats in both lake and stream systems. This paper reviews such impacts through the lens of UK surface water quality. Widely accepted climate change scenarios suggest more frequent droughts in summer, as well as flash-flooding, leading to uncontrolled discharges from urban areas to receiving water courses and estuaries. Invasion by alien species is highly likely, as is migration of species within the UK adapting to changing temperatures and flow regimes. Lower flows, reduced velocities and, hence, higher water residence times in rivers and lakes will enhance the potential for toxic algal blooms and reduce dissolved oxygen levels. Upland streams could experience increased dissolved organic carbon and colour levels, requiring action at water treatment plants to prevent toxic by-products entering public water supplies. Storms that terminate drought periods will flush nutrients from urban and rural areas or generate acid pulses in acidified upland catchments. Policy responses to climate change, such as the growth of bio-fuels or emission controls, will further impact freshwater quality.

Rethinking patch size and isolation effects: the habitat amount hypothesis

Abstract: I challenge (1) the assumption that habitat patches are natural units of measurement for species richness, and (2) the assumption of distinct effects of habitat patch size and isolation on species richness. I propose a simpler view of the relationship between habitat distribution and species richness, the ‘habitat amount hypothesis’, and I suggest ways of testing it. The habitat amount hypothesis posits that, for habitat patches in a matrix of non-habitat, the patch size effect and the patch isolation effect are driven mainly by a single underlying process, the sample area effect. The hypothesis predicts that species richness in equal-sized sample sites should increase with the total amount of habitat in the ‘local landscape’ of the sample site, where the local landscape is the area within an appropriate distance of the sample site. It also predicts that species richness in a sample site is independent of the area of the particular patch in which the sample site is located (its ‘local patch’), except insofar as the area of that patch contributes to the amount of habitat in the local landscape of the sample site. The habitat amount hypothesis replaces two predictor variables, patch size and isolation, with a single predictor variable, habitat amount, when species richness is analysed for equal-sized sample sites rather than for unequal-sized habitat patches. Studies to test the hypothesis should ensure that ‘habitat’ is correctly defined, and the spatial extent of the local landscape is appropriate, for the species group under consideration. If supported, the habitat amount hypothesis would mean that to predict the relationship between habitat distribution and species richness: (1) distinguishing between patch-scale and landscape-scale habitat effects is unnecessary; (2) distinguishing between patch size effects and patch isolation effects is unnecessary; (3) considering habitat configuration independent of habitat amount is unnecessary; and (4) delineating discrete habitat patches is unnecessary.