S.s.s. Sarma

Universidad Nacional Autónoma de México | UNAM · Faculty of Higher Studies (F.E.S.) Iztacala

The ecological impact of invasive species may be less in communities with high species diversity. We hypothesized that the feeding rates of an invasive copepod would be unaffected by high species diversity of prey in the medium as compared with a native species which would have reduced feeding rates under similar conditions. The biotic resistance t...

We studied temporal variations in phenolic compounds from the hydrophyte Myriophyllum aquaticum collected from a shallow lake. The effects of macrophyte-conditioned medium containing phenols with other compounds and phenols only as well as plant tissue extracts were tested on the survival and reproduction of the rotifer Plationus patulus. Apical ti...

We hypothesized that cyclopoids, being predators, have a stronger allelopathic influence than calanoids on life-history variables of herbivorous rotifers. To test this hypothesis, we quantified the allelopathic effects of conditioned medium obtained separately from males and females of a calanoid (Arctodiaptomus dorsalis) and a cyclopoid (Mesocyclo...

Mexico is a megadiverse country, with 10% of all known species found within its borders. The CONABIO catalogue registers rotifers as one of the best-studied groups of animals in Mexico, with the number of species recorded representing 18% of the total global rotifer fauna. However, this registry does not record a single exotic species of Rotifera i...

Life history strategies of rotifers vary in relation to their habitats. We compared the demography of Hexarthra jenkinae (de Beauchamp, 1932) from ephemeral pools and the large, permanent Nabor Carrillo Lake, both parts of the saline Lake Texcoco in Mexico. Population growth tests were conducted at salinities of 10, 12.5 and 15 g l−1 (1:1 ratio of...

Successful larval rearing of many fish species depends on the adequate selection of live food. Rotifers of the genus Brachionus are the most widely used in feeding protocols for freshwater and marine aquaculture. In this work, the utility of the euryhaline rotifer Proales similis as potential prey for the freshwater pike silverside Chirostoma estor...

We tested the effect of different food (Chlorella vulgaris) concentrations on the population growth and demographic variables of Dipleuchlanis propatula. In addition, we also tested the effect of competition from two other zooplankton species (a rotifer Plationus patulus and a ciliate Paramecium sp.). The parthenogenetic eggs of D. propatula carry...

We compared the demographic variables and bacterivory of two strains of Diaphanosoma mongolianum from two water bodies in Spain, one without Microcystis (Maidevera in Zaragoza) and the other with dense Microcystis (La Albufera of Valencia). We hypothesized that the strain rarely exposed to Microcystis would be unable to grow on this cyanobacterial...

The emerging contaminant 4-nonylphenol is an active ingredient in many surfactants. Though 4-nonylphenol has been reported in Mexican waterbodies, no stringent law is available to establish its permissible limits. Most ecotoxicological assays using zooplankton species are based on previously unexposed populations, and multigenerational experiments...

In aquatic systems, littoral zones provide heterogeneous environments and thus turbellarians can reach densities of up to 40,000 ind. m⁻² in these regions. To reach such high densities turbellarians need to feed on a variety of prey items. Very little information is available on the feeding ecology of Stenostomum spp. in natural conditions. The obj...

A review of the Mexican rotifer species diversity is presented here. To date, 402 species of rotifers have been recorded from Mexico, besides a few infraspecific taxa such as subspecies and varieties. The rotifers from Mexico represent 27 families and 75 genera. Molecular analysis showed about 20 cryptic taxa from species complexes. The genera Leca...

Valle de Bravo reservoir supplies drinking water to 40% of Mexico City. Here we present data on the population growth and life-table demography of the cladoceran Daphnia pulex, cultured at temperatures of 20 °C and 25 °C and with different concentrations of the crude extracts from blooms of Microcystis aeruginosa, collected in January, and Woronich...

Our understanding of the ecological drivers that control community structure of benthic rotifers is poorly known. By reviewing 21 papers on freshwater benthic rotifers we compiled an inventory of an additional 258 species, 27 genera, and six families not previously listed in the review of benthic, lotic rotifers by Ricci and Balsamo (Freshw Biol 44...

Over-exploitation of tropical lakes and reservoirs ('lakes') causes water quality problems that occur as a result of competing socioeconomic demands and the presence of feedback loops within the system that exacerbate the situation. We review well documented case studies from Brazil, India, Indonesia, Kenya, Malaysia and Mexico to examine the effec...

The Virgilio Uribe Rowing Canal in Xochimilco, Mexico City has cyanobacterial blooms throughout the year, often of the genus Microcystis. Here we evaluated the demographic responses of Moina macrocopa in the presence of cyanotoxins obtained by freezing and sonication of blooms collected in June (2017), September (2017) and March (2018). Acute toxic...

Diurnal temperature fluctuations affect ectothermic species more than endothermic taxa. We tested the effect of three fixed temperatures (20, 25 and 30 °C) and a 24 h variable (20–30 °C) on the population growth and fatty acid profiles of the common rotifer Brachionus calyciflorus. Depending on the temperature treatment, the peak population abundan...

Many aquarium fish species have diverse morphotypes. Since different morphotypes may have different preferences for various prey items, offering a single prey species is inadequate for successful aquaculture. Poecilia reticulata, a popular aquarium species, occurs in different morphotypes. To test whether the four morphotypes (yellow tail YT, red t...

Larvae of the sessile rotifer Cupelopagis vorax swim using their ciliated corona, but do not feed. Once they attach to a substratum and metamorphose into adults, they are predatory on protozoans and micrometazoans. Here we present information on ingestion time, feeding behaviour and food preference of C. vorax using protozoans and non‐sessile rotif...

Many urban lakes in Mexico City, such as Lake Chapultepec, are infested with high densities of cyanobacteria, particularly Microcystis. We tested the effect of cyanotoxins from cyanobacterial crude extracts on the demographic variables of zooplankton. The rotifers Brachionus havanaensis and Brachionus calyciflorus, and the cladocerans Ceriodaphnia...

Macrophytes sometimes become a nuisance, interfering with navigation, fishing, and aesthetic purposes. Therefore, in many water bodies, the macrophytes are periodically removed. However, with the removal of macrophytes, changes occur in the physico-chemical properties of water and the plankton associated with them. Here we describe the zooplankton...

Several abiotic factors influence the ecological responses of aquatic invertebrates to metal toxicity. We examined the effect of salinity (10, 20, and 30 psu) and temperature (25 and 32 °C) on acute and chronic arsenic (As) toxicity to the euryhaline rotifers, Proales similis and Brachionus ibericus. In general, higher salinities and low temperatur...

Research contribution by late Ramesh D Gulati

We hypothesised that at higher densities herbivorous rotifers through their allelochemicals affect the survival and reproduction of cladocerans. To test this, we separately cultured three rotifers (Brachionus calyciflorus, Brachionus havanaensis, and Plationus patulus) and three cladocerans (Ceriodaphnia dubia, Daphnia pulex, and Moina macrocopa)....

This Special Issue of Inland Waters (featuring 2 Special Sections spread across 2 issues) celebrates the contribution of Brian Moss to the science and management of freshwater ecosystems. Brian passed away in 2016, and since then much has been written about his life and achievements (Carvalho and Johnes 2016, Irvine and Barker 2016, Jeppesen and Jo...

We studied the seasonal variation of rotifers, cladocerans and copepods in Lake Zumpango, MexicoCity, from June 2010 to May 2011. Physical and chemical variables of the water were measured at three sites, while50 L of water was filtered from these sites to study the zooplankton abundance, diversity and biomass. The watertemperature ranged from 14 t...

Updated list of publications

Tropical waterbodies contain several species of toxic cyanobacteria including Microcystis, which adversely affect the somatic growth, survival and fecundity of zooplankton. Scenedesmus, one of the most common green algae, is even found in Microcystis-dominated waterbodies. It is, therefore possible that in natural ponds, rotifers and cladocerans fe...

We tested the effects of turbidity on the prey consumption by larvae of an endemic predator (Ambystoma mexicanum) and an introduced predator (Oreochromis niloticus). Prey visibility is influenced by turbidity due to organic (algae, detritus) or inorganic (sediment) matter. We hypothesized that the axolotl would be more adversely influenced by high...

The introduction of exotic species often results in a loss of biodiversity. Mexico has 4 invasive species of freshwater cyclopoid copepods: Thermocyclops crassus, Mesocyclops aspericornis, M. thermocyclopoides, and M. pehpeiensis. The Asian cyclopoid M. pehpeiensis is now established in several lakes and rivers in Mexico, but how it might compete w...

We determined numerical response, functional response, and prey selection by the predator Asplanchna girodi using 4 brachionid rotifer species, varying in size and lorica spines. We hypothesized that the consumption by the predators and thus population growth rates would be highest on prey with small spines compared with those with long spines. Dat...

Turbidity influences the success of fish feeding, but little is known about the difference in the effects of turbidity as a result of organic and inorganic matter. To assess the feeding behaviour of a native fish, Goodea atripinnis, under turbid conditions (up to 120 NTU) generated by Microcystis aeruginosa or silt, we conducted mesocosm experiment...

To better understand the sessile rotifer community of a shallow, eutrophic lake, we monitored over a 1‐year period the monthly changes in the density and diversity of rotifers on the roots of the common water hyacinth, Eichhornia crassipes, which served as a representative hydrophyte. Selected physical and chemical parameters of the water were also...

Rotifers and cladocerans compete for resources in freshwater ecosystems. Cladocerans, due to their large size, are competitively superior to rotifers. Cladocerans also release secondary metabolites into the medium which may be allelopathic to rotifers. However, in many eutrophic water bodies, rotifers are competitively dominant to cladocerans. We t...

In hypertrophic waterbodies, seston may be an important food for planktonic rotifers. Therefore, we hypothesized that seston in the hypertrophic waterbody (Lake Xochimilco, State of Mexico) supports high diversity and density of rotifers. To test this, we conducted growth experiments using six rotifer species (Brachionus bidentatus, Brachionus buda...

Cladocerans are constantly exposed to humic substances in nature, yet the effects of these substances on their survival and reproduction are not well known. Here, the effects of humic substances (20 and 40 mg L⁻¹) (HS) on the life history variables of three common cladocerans, Ceriodaphnia dubia, Moina macrocopa, and Daphnia pulex were evaluated. T...

Brachionus plicatilis is one of the most important rotifers used in aquaculture worldwide. We found a strain of B. plicatilis in Lake Pátzcuaro, a shallow water body in Central Mexico, which also supports several species of endemic fish. Here we present an investigation of the life-table demography and population growth of B. plicatilis at saliniti...

We have been culturing a species of Euchlanis cf. mikropous isolated from a river in Mexico. This species frequently loses its toes, which then reappear in successive generations. We studied the population dynamics of this species at different food levels of Chlorella vulgaris (0.25 × 10⁶, 0.5 × 10⁶ and 1.0 × 10⁶ cells ml⁻¹) and in the direct and i...

Increasing temperatures in aquatic ecosystems have resulted in changes in the proliferation patterns and persistence of cyanobacteria, particularly Microcystis sp.. In temperate lakes, large-sized herbivores such as Daphnia magna are used to control cyanobacterial blooms. The cladoceran, Simocephalus mixtus and the amphipod, Hyalella azteca are com...

Proliferating cyanobacterial blooms due eutrophication in reservoirs is a major global problem. The production of cyanotoxins often increases with grazing pressure and temperature while the sensitivity of zooplankton to cyanotoxins is directly related to temperature. Here we evaluate the effect of different concentrations of the crude extract of cy...

Cyanotoxins from toxic blooms in lakes or eutrophic reservoirs are harmful to several organisms including zooplankton, which often act as vectors of these secondary metabolites, because they consume cyanobacteria, bioaccumulate the cyanotoxins and pass them on along the food chain. Microcystins are among the most commonly found cyanotoxins and ofte...

We quantified the predation of Acanthocyclops americanus from the shallow Mediterranean lake Albufera, using gut contents from field collections and laboratory feeding tests. For functional response studies, we used Brachionus plicatilis (at 6 concentrations, 400–4000 ind. 40 ml⁻¹) and Diaphanosoma mongolianum (at 2–20 ind. 40 ml⁻¹). Copepod feedin...

Cladocerans feed on a variety of phytoplankton food sources, which are variable across space and time. Different phytoplankton groups represent different nutritional quality to Daphnia magna (Straus) due to differences in their Redfield stoichiometry or digestibility. We used chlorophyll fluorescence to directly measure phytoplankton group quantity...

Planktonic organisms are good indicators of water quality but are rarely used in Mexican riverine studies in spite of the high level of contamination in these lotic waters. In this study, we focused on the plankton of the river Amacuzac in Mexico and a large saline waterbody, Lake Tequisquitengo, which is located in the Amacuzac river basin. We col...

Some Moina species are predominantly found in large ponds and lakes while others are restricted to temporary pools or estuaries. The life history strategies and resistance to starvation of different species of Moina depend on their habitat. We compared the demography and starvation resistance in three species of the genus: Moina macrocopa (isolated...

Brachionus havanaensis is predominantly distributed in the Nearctic and Neotropical regions. It is now found even in the Palearctic and Oriental regions. During the summer of 2015 we found high densities (> 500 ind./l) of this species and low numbers of Brachionus angularis in Lake Albufera where the cyanobacterium (Microcystis aeruginosa) was domi...

Natural populations of planktonic rotifers are affected by salinity and food density, among other stressors. Moreover, competition among congeneric species limits the abundance of certain rotifers in ecosystems without spatial heterogeneity and environmental fluctuations. We isolated Brachionus plicatilis and Brachionus calyciflorus from Salado Riv...

We compared the interspecific effects of conditioned-medium containing allelochemicals from 4-rotifer species [(Brachionus calyciflorus (Pallas, 1776), Plationus patulus (Müller, 1786), Brachionus angularis (Gosse, 1851) and Brachionus havanaensis (Rousselet, 1911)] using population dynamics as a tool. All the four rotifer species were separately c...

Rotifer dominance in wetland ecosystems is due to their ability to survive and reproduce in the presence of cyanobacteria, ability to occupy different niches and elimination of competing crustaceans by predation. In addition, quality and quantity of food and physical and chemical variables affect the rotifer abundances in these waterbodies. Seasona...

To understand the population growth potential of different species of rotifers in nature, field collections through seasons are essential. We sampled zooplankton (and measured selected physicochemical variables) from the Madín reservoir, a high altitude eutrophic urban waterbody from Mexico, every month for a year. Qualitative analysis of zooplankt...

Antecedentes Myriophyllum aquaticum presenta una alta plasticidad fenotípica (heterofilia) y su dispersión está en función de su reproducción vegetativa; sus hojas sumergidas poseen características estructurales que permiten la liberación de compuestos orgánicos, dentro de los que se observan compuestos fenólicos. Objetivos El presente estudio ana...

Background: Myriophyllum aquaticum has a high phenotypic plasticity and its plant dispersion is a function of its fast vegetative reproduction; its submerged leaves possess structural characteristics that allow the release of organic compounds, among them phenolic compounds. Goals. Under laboratory conditions, this study analyzed the development of...

Abstract Endocrine disruptors are chemical substances that affect the hormonal and homeostatic systems of organisms. The importance of these systems is to communicate and respond to the changes in the environment. Among the different endocrine disruptors, bisphenol a, nonylphenol, triclosan, pharmaceuticals, estrogens and pesticides are generally c...

We isolated the rotifers Brachionus ibericus and Proales similis from the sediment of shrimp tanks and studied their individual demographic characters and competition between them at two food levels (0.25 × 10⁶, 1.00 × 10⁶ cells ml⁻¹ of Nannochloropsis oculata at 25 °C) and salinities ranging from 10 to 30‰. Our hypothesis was that growth rates wou...

The demographic response of the brackish-water rotifers Proales similis and Brachionus plicatilis to mercury (0.5, 2, 8 and 32 µg L-1 of HgCl2) at different salinity levels (10 and 20‰) and two temperature (25 °C and 32 °C) regimes were evaluated. Median lethal concentration (LC50) for P. similis and B. plicatilis was 10 and 16 μg L-1, respectively...

Aim: Brachionus calyciflorus and Plationus patulus are the two brachionid rotifers that are widely recognized as suitable bioassay species for testing the effects of toxicants and xenobiotics. However, their relative sensitivities vary depending on the duration of exposure, nature of the toxicants and the ecological tools used. Most ecotoxicologica...

Diabetes Type 2 is among the most common metabolic disorders that human beings face. As the number of diabetic patients increases, the demand for production of antidiabetic drugs also increases. This, in turn, raises environmental concerns since these drugs eventually reach water bodies through various means like, excretory wastes by the patients....

Aim: In the past two decades, studies on cryptic speciation have increased rapidly leading to the need to reconsider cosmopolitanism in Rotifera. Cryptic species complexes are reported in some taxa of rotifers, especially Brachionidae and Epiphanidae. Less is known about Asplanchnidae although several morphotypes are known to exist. In this work, w...

Aim: Llano reservoir is a high altitude waterbody and is of recreational importance in Mexico. It is also a source of revenue through fisheries. Though the reservoir was constructed nearly 6 decades ago, quantitative information on the zooplankton abundance is not available. The aim of the present study was to present data on the seasonal variation...

Aim: Food availability during the early developmental stages of larval salamanders is a bottleneck for their successful breeding strategies and the conservation of amphibians. Zooplankton based diets allow salamander larvae to choose different prey types based on their size and energy gains. In this study, we quantified the patterns of prey selecti...

Aim: Lake Xochimilco is shallow (< 2m) water-body in Mexico City consisting of several interconnected canals. It is now eutrophic, with high levels of turbidity as a result of suspended sediment and phytoplankton blooms. We selected two sites, the Rowing channel with organicturbidity due to cyanobacterial blooms and the Main channel with inorganic...