The Lorenz Curve: A Proper Framework to Define Satisfactory Measures of Symbol Dominance, Symbol Diversity, and Information Entropy.

Novel measures of symbol dominance ( and ), symbol diversity ( = (1 - ) and = (1 - )), and information entropy ( = log and = log ) are derived from Lorenz-consistent statistics that I had previously proposed to quantify dominance and diversity in ecology. Here, refers to the average absolute difference between the relative abundances of dominant and subordinate symbols, with its value being equivalent to the maximum vertical distance from the Lorenz curve to the 45-degree line of equiprobability; refers to the average absolute difference between all pairs of relative symbol abundances, with its value being equivalent to twice the area between the Lorenz curve and the 45-degree line of equiprobability; is the number of different symbols or maximum expected diversity. These Lorenz-consistent statistics are compared with statistics based on Shannon's entropy and Rényi's second-order entropy to show that the former have better mathematical behavior than the latter.

Responses of aquatic macrophytes to anthropogenic pressures: comparison between macrophyte metrics and indices.

Macrophyte responses to anthropogenic pressures in two rivers of Central Spain were assessed to check if simple metrics can exhibit a greater discriminatory and explanatory power than complex indices at small spatial scales. Field surveys were undertaken during the summer of 2014 (Duraton River) and the spring of 2015 (Tajuña River). Aquatic macrophytes were sampled using a sampling square (45 × 45 cm).

Ecotoxicological assessment of the impact of fluoride (F) and turbidity on the freshwater snail Physella acuta in a polluted river receiving an industrial effluent.

We carried out field studies and laboratory experiments to assess the impact of fluoride (F) and turbidity on the freshwater snail Physella acuta in a polluted river receiving an industrial effluent (the middle Duraton River, Central Spain). Fluoride concentrations and turbidity levels significantly increased downstream from the industrial effluent (with the highest values being 0.6 mg F/L and 55.

Development of a Low-Cost Ecotoxicological Bioassay Based on the Feeding Behaviour of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

Conventional acute tests are not suited to assess the effects of toxicants, because they do not use the concentrations that are usually found in natural ecosystems. By contrast, nonlethal realistic concentrations may cause deleterious effects on animal fitness as a consequence of behaviour impairment. Behaviour is a good integrative variable of complex biochemical and physiological processes.

Ammonia toxicity to the freshwater planarian Polycelis felina: contrasting effects of continuous versus discontinuous exposures.

Aquatic animals can be exposed to fluctuating concentrations of toxicants. In fact, for some toxicants (i.e.

Ecotoxicological assessment of the impact of nitrate (NO(3)(¯)) on the European endangered white-clawed crayfish Austropotamobius italicus (Faxon).

Field studies and laboratory experiments were conducted to assess the impact of elevated nitrate (NO(3)(¯)) concentrations on the European endangered white-clawed crayfish Austropotamobius italicus (Faxon) in the Henares River Basin (Central Spain), within an area that is vulnerable to nitrate pollution. Two sampling surveys were carried out in the summer of 2009 and 2011 to collect freshwater crayfish at eight sampling sites along this vulnerable area. The invasive read-swamp crayfish Procambarus clarkii (Girard) was the only collected crayfish species.

Assessment of drift as a recovery endpoint in aquatic snails exposed to ammonia.

Pollutants are an important factor that causes among others drift (i.e. downstream transport of aquatic organisms in the current) in aquatic invertebrates.

Reproductive traits and population structure of Astyanax aeneus (Characiformes: Characidae) from a subtropical river in Mexico.

Champotón River is an unknown area within the Mesoamerican hotspot in Southestern México. Reproductive traits and population structure of Astyanax aeneus were analyzed along an environmental gradient of the upper, middle and lower sections of the river, where diverse environmental factors were recorded. For this, nets were cast for 1 h at each site and A.

The impact of an industrial effluent on the water quality, submersed macrophytes and benthic macroinvertebrates in a dammed river of Central Spain.

This research was conducted in the middle Duratón River (Central Spain), in the vicinity of Burgomillodo Reservoir. An industrial effluent enters the river 300 m downstream from the dam. Fluoride and turbidity levels significantly increased downstream from the effluent, these levels being to some extent affected by differential water releases from the dam.

Fluoride bioaccumulation and toxic effects on the survival and behavior of the endangered white-clawed crayfish Austropotamobius pallipes (Lereboullet).

Laboratory experiments were performed to examine the toxic effects of fluoride (F(-)) on the survival and behavior of white-clawed crayfish (Austropotamobius pallipes). Body fluoride contents (bioaccumulation) of test crayfish were also examined. No significant differences between male and female crayfish regarding mortality, escape (tail-flip) response, and fluoride bioaccumulation were detected.

Nitrate causes deleterious effects on the behaviour and reproduction of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

Nitrate (NO3 (-)) is present in aquatic ecosystems as a natural component of the nitrogen cycle. However, in the last decades, several human activities are the causes of the rising amounts of organic matter and inorganic nitrogen nutrients in aquatic ecosystems, causing notable increase of nitrate above background natural levels. In spite of the toxicity of nitrate to aquatic animals, there are relatively few studies on the chronic toxicity of this compound to invertebrates.

A video-based tracking analysis to assess the chronic toxic effects of fluoride ion on the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

Short-term lethal bioassays are not suited for assessing the real effects of pollutants in natural ecosystems, as their concentrations are usually unrealistic under an ecological point of view. By contrast, chronic bioassays are more realistic for assessing effects on aquatic animals, especially when behavioural endpoints are used. These endpoints are a good link between physiological and ecological effects.

The freshwater planarian Polycelis felina as a sensitive species to assess the long-term toxicity of ammonia.

Behavioural endpoints are a good link between physiological and ecological effects. However long-term behavioural endpoints are not uniformly studied over all different organism groups. For example behaviour has been scarcely studied in planarians.

Contrasting sensitivities to fluoride toxicity between juveniles and adults of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

In contrast to aquatic vertebrates, there is scarce available information on the contrasting tolerance to fluoride of different life stages and/or sizes of aquatic invertebrates. The purpose of this study was to assess the likely differences in sensitivity between juveniles and adults of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca) to short-term (4 days) toxicity of fluoride ion (F(-)). LC50 and EC50 values for juveniles were significantly lower than those for adults at 24, 48, 72 and 96 h.

Fluoride toxicity and bioaccumulation in the invasive amphipod Dikerogammarus villosus (Sowinsky, 1894): a laboratory study.

The tolerance of the invasive amphipod Dikerogammarus villosus to fluoride (F⁻) toxicity was examined via laboratory experiments. 96-h LC₅₀ and 240-h NOEC values were estimated to be 5.8 and 0.

Subchronic toxic effects of fluoride ion on the survival and behaviour of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

Short-term bioassays usually assess lethal effects of pollutants in animals, whereas subchronic bioassays are more suited for assessing effects on animal behaviour. Among them, videotaped bioassays are an improvement in the behavioural monitoring because they are easily and cheaply implemented. The present study focuses on the assessment of subchronic (14-day) effects of fluoride ion on the survival, proportion of dead plus immobile animals, and velocity (monitored by a videotaping and image analysis system) of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

Effects of pulse duration and post-exposure period on the nitrite toxicity to a freshwater amphipod.

This research assesses the effects of nitrite pulses and post-exposure periods after nitrite exposures on the survival of the freshwater amphipod Eulimnogammarus toletanus. A toxicity bioassay was performed using three different nitrite concentrations (0.5, 5.

Long-term effects of ammonia on the behavioral activity of the aquatic snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca).

An appropriate approach to assess the effect of toxicants on aquatic animals is to monitor behavioral endpoints, as they are a link between physiological and ecological processes. A group that can be exposed long-term to low toxic concentrations is benthic macroinvertebrates, as their mobility in aquatic ecosystems is relatively limited. Therefore, the study of behavioral long-term effects in this group is suitable from an ecological point of view, as behavioral effects can appear before mortality.

Revisiting the relation between species diversity and information theory.

The Shannon information function (H) has been extensively used in ecology as a statistic of species diversity. Yet, the use of Shannon diversity index has also been criticized, mainly because of its ambiguous ecological interpretation and because of its relatively great sensitivity to the relative abundances of species in the community. In my opinion, the major shortcoming of the traditional perspective (on the possible relation of species diversity with information theory) is that species need for an external receiver (the scientist or ecologist) to exist and transmit information.

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment.

We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) it can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of aquatic ecosystems; (3) it can reach toxic levels that impair the ability of aquatic animals to survive, grow and reproduce. Inorganic nitrogen pollution of ground and surface waters can also induce adverse effects on human health and economy.

Ecotoxicological assessment of the impact of residual heavy metals on soil nematodes in the Guadiamar River Basin (Southern Spain).

On 25 April 1998, as a consequence of the breaking of a dam containing the tailings of a pyrite mine, a land strip of approximately 43 km in length was covered with a layer of black sludge, containing high levels of heavy metals, along the Guadiamar River Basin (southern Spain). In this investigation we carried out an ecotoxicological assessment (field and laboratory studies) of the impact of residual heavy metals (Cu, Pb, Zn, Ni) on soil nematodes in the impacted riparian zone, two years after the huge mine spillage. Concentrations of residual heavy metals were significantly (P<0.

Toxicity of nitrite to three species of freshwater invertebrates.

Nitrite is a compound with a high toxicity to aquatic animals. Several anthropogenic pollution sources are increasing the concentrations of this component of the nitrogen cycle. Despite this toxicity, there is little available literature on its effects on freshwater invertebrates.

Eutrophication downstream from small reservoirs in mountain rivers of Central Spain.

In this research we examined the hypothesis that upper reaches of rivers and streams can experience eutrophication as a consequence of deep releases from dams. Field studies were conducted in four mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks.