Mirriam Kannan

Northern Kentucky University, Biological Sciences, Faculty Member

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The fossil diatoms of lake Yambo, Ecuador. A possible records of El Niño events

Bulletin de l’Institut français d’études andines

Fossil diatoms from a sediment core of Lake Yambo, a lake in an endorheic, desert region of the E... more Fossil diatoms from a sediment core of Lake Yambo, a lake in an endorheic, desert region of the Ecuadorian Andes, provide a record of precipitation events that can be linked to the ENSO phenomenon. Abnormally high precipitation in the region during the 1982-83 El Niño caused a substantial drop in the lake's conductivity. The diatom flora in the lake changed from a community dominated by the halophilic species Cratícula halophila Cratícula halophila to one dominated by a freshwater species Aulacoseira distans Aulacoseira distans. Similar shifts in dominance can be seen at various points throughout the core. There also appears to be an increase in sediment deposition at these points. This paper provides the first evidence that the use of fossil diatoms from lake cores can be a valuable tool in reconstructing histories of El Niño events.

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Amazon without refugia: vegetation and climate of the Amazon basin through a glacial cycle

POLY 404-Effect of turbulence on biosilica structure and morphology

The frustules of diatoms may be manipulated by external stimuli. In this presentation we will rep... more

Paul Colinvaux 1930–2016

The Bulletin of the Ecological Society of America, 2016

Characterizing Short-Term (1970-PRESENT) Lake Change in the High-Mountain Tropics and Amazon of Ecuador

Comparing Andean and Interandean Lakes at Decadal and Centennial Scales

Geological Society of America Abstracts with Programs, 2019

Amoebae Assemble Synthetic Spherical Particles To Form Reproducible Constructs

Langmuir, 2019

Difflugia are testate Amoebae that use particulate inorganic matter to build a protective shell (... more Difflugia are testate Amoebae that use particulate inorganic matter to build a protective shell (generally called a test or theca). Difflugia globulosa were grown both in culture containing only naturally occurring theca building materials and under conditions where synthetic particles were present as well. The presence of particles, monodisperse Stöber silica microspheres of 1, 3 and 6 µm diameter or 4 µm polystyrene spheres, dramatically increased the rate of Difflugia growth, and foreign microspheres became the overwhelmingly dominant

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Beyond El Ni�o: Decadal and Interdecadal Climate Variability

J Paleolimnol, 2001

POLY 531 Effect of flow on the structure of biological and synthetic minerals

Diatoms have ornate biosilica frustules that are species-specific and are formed under genetic co... more Diatoms have ornate biosilica frustules that are species-specific and are formed under genetic control. We have observed interesting changes in the shape of diatoms both in laboratory cultures and in nature when they are exposed to different environmental conditions such as flow rate or UV radiation. It has been recently discovered that biosilica formation is facilitated by a variety of biological organic molecules. For example, it is proposed that silaffin proteins and ‘small' propylamines are involved in diatom biosilicification. In order to us help to understand the role(s) of organic biomolecules in vivo, model in vitro studies have been carried out where synthetic and biological molecules have been studied for their effects on silica formation. The study of silica formation using R5 peptide which is derived from silaffin proteins is one such example. An interesting observation is that flow can change the structure of both synthetic and biological minerals.

Book Review: Guide to the Common Fungi of the Semiarid Region of BrazilGuide to the Common Fungi of the Semiarid Region of Brazil. By Maria A. Neves , Iuri G. Baseia , E. Ricardo Drechsler-Santos , and Aristóteles Góes-Neto [eds]. 132 pp. TECC Editora, Florianópolis, Brazil. USD $35. 978-85-65005...

The Journal of the Torrey Botanical Society, 2014

This is a richly illustrated, bilingual (English and Portuguese) field guide to macroscopic fungi... more This is a richly illustrated, bilingual (English and Portuguese) field guide to macroscopic fungi found in the semiarid region of northeastern Brazil. It is intended for students and professional mycologists, but will appeal to anyone interested in fungi. Although designed to cover areas of Brazil, many of the 84 species described in this guide are widespread throughout South and North America. The book starts with an introduction to the semiarid region of Brazil that includes a map of the focus area. It is followed by a short introduction to the kingdom Fungi, indicating their importance and listing the seven phyla recognized in the kingdom. The rest of the book is divided into four sections, one for the Ascomycota and the three others for the Basidiomycota. The sections group taxa according to morphology to make the guide ‘‘user-friendly’’ and therefore may lump in a section species that are not necessarily taxonomically closely related. Each section starts with a dichotomous key to the species in that section, followed by descriptions, color photographs, and illustrations of the sexual spores for each taxon. Section one has 11 species of Ascomycota (9 with photographs); section 2, the ‘‘classic’’ mushrooms (22 species); section three has the polypores or bracket fungi (28 species); and the fourth section the gasteromycetes, or Gasteroid fungi, that produce their spores inside basidiocarps (fruit bodies; 23 species). There are two Appendices (in Portuguese only). Appendix I describes collecting and preserving methods, and gives general illustrated descriptions of fungal forms and their spores, and Appendix II is a glossary of terms used in the keys. There is a short Literature Cited section and an index of scientific names. The beauty of this book is in the color photographs, the illustrations, and detailed descriptions. Each description also includes the habitat where the fungi can be found–for example, ‘‘on manure of cattle and horses,’’ ‘‘on decomposing wood,’’ or ‘‘on sandy soil.’’ Anyone from the professional to the amateur mycologist would enjoy taking this book in the field. It is easy to use, and the photographs make it a wonderful book! Maravilhoso livro!—MIRIAM STEINITZ-KANNAN, Department of Biological Sciences, Northern Kentucky University, Highland Heights, KY 41099-0400. Journal of the Torrey Botanical Society 141(3), 2014, pp. 275

Impacts of climate variability and human colonization on the vegetation of the Galápagos Islands

Ecology, 2012

A high-resolution (2-9 year sampling interval) fossil pollen record from the Galápagos Islands, w... more A high-resolution (2-9 year sampling interval) fossil pollen record from the Galápagos Islands, which spans the last 2690 years, reveals considerable ecosystem stability. Vegetation changes associated with independently derived histories of El Niño Southern Oscillation variability provided evidence of shifts in the relative abundance of individual species rather than immigration or extinction. Droughts associated with the Medieval Climate Anomaly induced rapid ecological change that was followed by a reversion to the previous state. The paleoecological data suggested nonneutral responses to climatic forcing in this ecosystem prior to the period of human influence. Human impacts on the islands are evident in the record. A marked decline in long-term codominants of the pollen record, Alternanthera and Acalypha, produced a flora without modern analogue before 1930. Intensified animal husbandry after ca. 1930 may have induced the local extinction of Acalypha and Alternanthera. Reductions in populations of grazing animals in the 1970s and 1980s did not result in the return of the native flora, but in invasions by exotic species. After ca. 1970 the trajectory of habitat change accelerated, continuously moving the ecosystem away from the observed range of variability in the previous 2690 years toward a novel ecosystem. The last 40 years of the record also suggest unprecedented transport of lowland pollen to the uplands, consistent with intensified convection and warmer wet seasons.

Data from: Geo-climatic factors drive diatom community distribution in tropical South American freshwaters

1.Patterns that maintain and generate biodiversity of macro-organisms in the Neotropics are widel... more 1.Patterns that maintain and generate biodiversity of macro-organisms in the Neotropics are widely discussed in the scientific literature, yet the spatial ecology of microorganisms is largely unknown. The unique character of the tropical Andes and adjacent Amazon lowlands generates a wide gradient of environmental conditions to advance our understanding of what drives community assembly and diversity processes. 2.We analyzed the distribution patterns of benthic diatoms (unicellular siliceous algae) as a model group of microbial passive dispersers, including predictors that describe limnological and geo-climatic gradients for a total of 113 waterbodies (0–28ºS and 58–80ºW), including lakes and streams. Complementary multivariate statistical analyses were performed to correlate i) community composition, and ii) diatom species richness with environmental and spatial factors to infer niche-based and dispersal-based assembly processes, respectively. 3.Results showed that two gradients structured both diatom assemblages and waterbodies, namely climate and landscape configuration. Variance partitioning revealed that broad-scale spatial variables (distance-based Moran's Eigenvectors) outperformed the two environmental components (limnological and geo-climatic), suggesting dispersal-assembled communities. However, diatom assemblages were structured by geo-climatic (regional) factors in certain lakes in the northern and central Andes, although their effects were partially manifested via local variables after the geographical distances were factored out. In a similar way, climatic and topographic structuring homogenized lake and stream communities within ecoregions, as indicated by the strong overlap between the two community types and the weak correlation between biota and limnological variables. Notably, a significant increase in diatom species richness was related to increased water connectivity, interpreted to indicate that a decrease in the remoteness of the system increase species number. 4.Synthesis. We emphasize the strength of macroecological gradients (landscape configuration and climatic factors) in affecting both diatom diversity and community composition in the South American tropics. In this context, our results and the commonalities of ecoregion patterning with groups of macroorganisms (vegetation), suggest the need to integrate microbial ecology into a macroecology framework to unravel mechanisms behind diversity gradients

Appendix A. A figure showing asymptotes reached at 250 grains counted for total pollen sums in both the uppermost sample and the sample at 12 cm depth

A figure showing asymptotes reached at 250 grains counted for total pollen sums in both the upper... more

Appendix B. A table of radiometric ages upon which the chronology is based

A table of radiometric ages upon which the chronology is based.

Appendix D. A table of corresponding age (AD/BC) for each of the depths sampled

A table of corresponding age (AD/BC) for each of the depths sampled.

Appendix E. The total number of taxa found in the El Junco crater lake pollen record, 105 pollen and spores types

The total number of taxa found in the El Junco crater lake pollen record, 105 pollen and spores t... more

Appendix F. A figure showing ecological change derived from pollen data of El Junco crater lake in which selected times are set to zero to form a baseline with which change can be compared

A figure showing ecological change derived from pollen data of El Junco crater lake in which sele... more

Harmful Algae Bloom Occurrence in Urban Ponds: Relationship of Toxin Levels with Cell Density and Species Composition

Journal of earth and environmental sciences, 2017

Retention ponds constructed within urban watershed areas of high density populations are common a... more Retention ponds constructed within urban watershed areas of high density populations are common as a result of green infrastructure applications. Several urban ponds in the Northern Kentucky, USA area were monitored for algal community (algae and cyanobacteria) from October 2012 to September 2013. Many of the harmful algal blooms observed during this study were composed primarily of the cyanobacteria genus, Microcystis. No correlations were observed between basic water quality parameters (dissolved oxygen, pH, conductivity, temperature, nitrate and soluble reactive phosphate) and the presence of cyanobacteria and/or microcystin cyanobacterial toxin levels. Furthermore, levels of microcystin toxins did not always coincide with high Microcystis cell counts. Harmful algal blooms in small urban ponds are common which pose risk to human and ecological health due to proximity of dense human population including pets and wild animals. Because harmful algal blooms were detected throughout t...

Appendix C. Figures showing the inferred pattern of sediment accumulation in cores EJ-N-1 and EJ-2 raised from El Junco crater lake

Figures showing the inferred pattern of sediment accumulation in cores EJ-N-1 and EJ-2 raised fro... more

Estudios limnologicos en la Laguna de San Marcos con descripciones de las especies principales de diatomeas

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