Headwaters (stream orders 1–2) traditionally have been considered depauperate compared to mid-order streams (orders 3–4)—a conclusion that arises from a perception of streams as linear systems and emphasizes change in average α (local) diversity along streams. We hypothesized an opposite pattern for β (among-site) diversity and suggest that headwaters might account for a large degree of basin-scale biodiversity if considered within the more realistic framework of streams as branching networks. We assembled pre-existing biodiversity data from across the globe to test this hypothesis broadly at the population-genetic (mitochondrial haplotype diversity within species) and community (species/taxonomic diversity) levels, with a focus on macroinvertebrates. We standardized 18 (9 headwater and 9 mid-order) population-genetic and 16 (10 headwater and 6 mid-order) community-level ecoregional data sets from 5 global ecozones for robust comparisons of β-diversity estimates between the 2 stream-size categorie...

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Small but mighty: headwaters are vital to stream network biodiversity at two levels of organization

This paper introduces a series of contributions to the ninth meeting of the International Association of Phytoplankton Taxonomy and Ecology, held in Belgium during July, 1993 It draws from the original papers a synthesis which supports the view that the successful species in rivers and turbid shallow lakes are selected primarily on their ability to survive high-frequency irradiance fluctuations as they are circulated through steep light gradients The selective distinction is less than that which discriminates between plankton of deep lakes and shallow lakes or even between clear and turbid shallow ones River plankton is, however, dependent on fast growth rates but its survival in rivers is aided by a suite of water-retentive mechanisms The ecology of turbid systems is dominated by physical interactions, those biotic interactions traditionally believed to regulate limnetic communities being suppressed and rarely well-expressed

Are phytoplankton dynamics in rivers so different from those in shallow lakes

Effects of photoperiod on nutrient removal, biomass production, and algal-bacterial population dynamics in lab-scale photobioreactors treating municipal wastewater.

A novel machine learning-based approach for the risk assessment of nitrate groundwater contamination

Groundwater nitrate pollution and human health risk assessment by using HHRA model in an agricultural area, NE China

A structural analysis of river phytoplankton has been carried out based upon published studies on 67 rivers. When available on a yearly basis to account for seasonal variability, five structural features have been chosen: species composition, species richness, species dominance, diversity and biomass (total and per taxonomic groups). Despite the high number of reported studies, most of them cover only some of the aforementioned features. As a result of the low amount of studies, tropical rivers are underepresented. No size distribution studies have been carried out on river phytoplankton. The average species richness amounts to 126, being higher in temperate rivers. Roughly one half of each flora is comprised of sporadic species. No statistically significant relationship between species richness and latitude has been found despite the fact that tropical rivers appear to house fewer species than temperate rivers. Also, one half of the support in the floras are either benthic or tychoplanktonic. Diatoms comprise the majority of species numbers in the whole data set but are substituted by desmids in tropical rivers and by green algae when benthic species are not taken into account. There appears to be lower biomass in river phytoplankton than in lakes. Diatoms are also the major taxonomic group comprising total biomass in rivers but they share clearly a lower fraction in tropical rivers. On an average basis, diatoms appear to be more dominant in rivers than in lakes. The time course of diatom dominance occurs close to the summer solstice in tropical rivers whereas is much more lagged in temperate sites. The diversity of river phytoplankton is highly scattered (0.40–4.40 bits ind−1).

An elementary, structural analysis of river phytoplankton

https://digital.csic.es/bitstream/10261/205492/1/2017%20Arauzo%2c%20LU-IV%20procedure.pdf

Vulnerability of groundwater resources to nitrate pollution: A simple and effective procedure for delimiting Nitrate Vulnerable Zones

The intrinsic vulnerability of groundwater in the Comunidad de Madrid (central Spain) was evaluated using the DRASTIC and GOD indexes. Groundwater vulnerability to nitrate pollution was also assessed using the composite DRASTIC (CD) and nitrate vulnerability (NV) indexes. The utility of these methods was tested by analyzing the spatial distribution of nitrate concentrations in the different aquifers located in the study area: the Tertiary Detrital Aquifer, the Moor Limestone Aquifer, the Cretaceous Limestone Aquifer and the Quaternary Aquifer. Vulnerability maps based on these four indexes showed very similar results, identifying the Quaternary Aquifer and the lower sub-unit of the Moor Limestone Aquifer as deposits subjected to a high risk of nitrate pollution due to intensive agriculture. As far as the spatial distribution of groundwater nitrate concentrations is concerned, the NV index showed the greatest statistical significance (p < 0.01). This new type of multiplicative model offers greater accuracy in estimations of specific vulnerability with respect to the real impact of each type of land use. The results of this study provide a basis on which to guide the designation of nitrate vulnerable zones in the Comunidad de Madrid, in line with European Union Directive 91/676/EEC.

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Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution

Spatio-temporal dynamics of nitrogen in river-alluvial aquifer systems affected by diffuse pollution from agricultural sources: Implications for the implementation of the Nitrates Directive

http://digital.csic.es/bitstream/10261/122574/3/Short%20term%20harmful%20%20Arauzo%202003.pdf

Mercedes Arauzo

Papers

An elementary, structural analysis of river phytoplankton

Vulnerability of groundwater resources to nitrate pollution: A simple and effective procedure for delimiting Nitrate Vulnerable Zones

Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution

Spatio-temporal dynamics of nitrogen in river-alluvial aquifer systems affected by diffuse pollution from agricultural sources: Implications for the implementation of the Nitrates Directive

Short-term harmful effects of unionised ammonia on natural populations of Moina micrura and Brachionus rubens in a deep waste treatment pond.