This comprehensive book provides a unique overview of advances in the biology and ecology of marine protists. Nowadays marine protistology is a hot spot in science to disclose life phenomena using the latest techniques. Although many protistological textbooks deal with the cytology, genetics, ecology, and pathology of specific organisms, none keeps up with the quick pace of new discoveries on the diversity and dynamics of marine protists in general. The bookMarine Protists: Diversity and Dynamics gives an overview of current research on the phylogeny, cytology, genomics, biology, ecology, fisheries, applied sciences, geology and pathology of marine free-living and symbiotic protists. Poorly known but ecologically important protists such as labyrinthulids and apostome ciliates are also presented in detail. Special attention is paid to complex interactions between marine protists and other organisms including human beings. An understanding of the ecological roles of marine protists is essential for conservation of nature and human welfare. This book will be of great interest not only to scientists and students but also to a larger audience, to give a better understanding of protists’ diverse roles in marine ecosystems.

The oceans are microbial-dominated ecosystems, where protists (single-celled eukaryotes) play fundamental roles performing multiple functions as primary producers, consumers, decomposers as well as trophic linkers in aquatic food webs. Due to their ecological relevance, it is important to characterize protist communities along temporal and spatial gradients to understand their biogeography and dynamics. This will allow us to infer the processes that drive the assembly of protist communities. In this dissertation, we focused in the study of natural protists communities aiming to understand their distributions and responses within different dimensions. We first focused in the temporal dimension, analyzing the dynamics of pico- and nanoeukaryotic communities, aiming to characterize the diverse strategies of their members and to determine seasonality. We identified an annual seasonal pattern in the protist community as well as in several composing taxa. Then, we addressed the spatial dimension, analyzing the changes in community composition along the water column in 13 stations distributed in the global ocean, exploring also the vertical variation in the relative metabolic activity of different taxa. Our results showed a clear vertical stratification of the community and indicated that the mesopelagic layer is the region with the highest metabolic activity. Another aim of this thesis was to explore the response of natural protists to chemical gradients. The ocean is a complex ecosystem with nutrients heterogeneously distributed along several patches, so there may be a lot of chemical gradients promoting diverse responses on marine microbes. For that purpose, we performed chemotactic experiments to identify individual responses towards different attractants within a natural protist community. The experimental results showed a preferential response towards some of the tested chemical cues, mainly bacterial exudates. Finally, since studies on microbial diversity generally use the relative abundances of phylotypes in a given sample, we explored the relationship between the latter relative abundances to cell abundances in several chosen taxa. In sum, this dissertation determines temporal and spatial patterns in protists communities as well as chemotactic preferences in different taxa, contributing to broaden our understanding of the structuring processes operating across temporal, spatial and behavioral dimensions in the protist world.

Planktonic protists both produce and consume most of the primary production in the world ocean. They not only play key roles in the oceans but also represent an astounding amount of diversity: ecological morphological and genetic. However, for most taxa their ecology, morphology, phylogeny and biogeography are either poorly known or appear to be largely unrelated to one another; this hinders our understanding of their biology as well as interpretation of emerging genetic data. Tintinnid ciliates represent a singular exception. Compared to nearly all other groups of planktonic protists, there is a very substantial and relatively detailed literature (both modern and historical) on tintinnids. This volume synthesizes knowledge concerning a wide variety of topics ranging from anatomy and systematics, physiology, behavior, ecology (including ecological roles, predators, parasites, biogeography, and cysts) to fossil history. It will appeal to an audience ranging from advanced undergraduates to researchers in the fields of Oceanography, Marine Biology and Microbial Ecology.

A comprehensive guide to the protists that live in the surface waters and sea-ice south of the Antarctic Polar Front.

Heterotrophic protists are abundant and ecologically important members of marine ecosystems. They influence energy flow and biogeochemical cycling by consuming prokaryotes and remineralizing nutrients. They also serve as trophic links between microbial and metazoan food webs. To advance our understanding of microbial community structure and trophic relationships, I aim to characterize the distributions, diversity and trophic dynamics of heterotrophic protists in three different marine ecosystems using a combination of microscopy, molecular and analytical approaches. Using epifluroescence microscopy, I completed the first characterization of seasonal variability in abundance, biomass and size structure of pico- and nano-sized autotrophic and heterotrophic protists at Stn. ALOHA. This study indicates that trophic interactions of protistan grazers impact the structure of lower trophic levels over seasonal and interannual time-scales. The novel application of a method developed for simultaneous determination of rates of viral lysis and grazing mortality in the California Current Ecosystem enabled me to examine the relationships between picoplankton growth and mortality over a range of environmental conditions. The variability in mortality patterns for individual populations and inverse relationship between virus and grazer impacts highlight the complexity of predator-prey interactions in the marine environment. The use of molecular methods in a deep-sea methane seep enabled me to characterize the spatial distribution and diversity of marine protists in response to habitat heterogeneity within seep sediments and provide insights into the environmental factors that structure protistan communities on a range of spatial scales. In addition, the discovery of folliculinid ciliates living in five methane seeps along the Pacific margin is notable because this group of protists is a previously unrecognized, but potentially ecologically important component of seep ecosystems. Using a combination of molecular and analytical tools, I was able to provide the first direct evidence for the incorporation of methane-derived carbon by protists in deep-sea methane seep ecosystems. Characterizing protistan communities and their trophic interactions in response to varying environmental conditions is a key step towards understanding how this group of organisms influences microbial community structure and ecosystem function. The results from these studies highlight the importance of mortality processes, not just variations in growth, for structuring microbial communities. They also demonstrate how continued use and integration of multiple complementary approaches will enhance progress in exploring the underlying mechanisms regulating microbial community structure and trophic dynamics. Such information is critical for accurately predicting the response of microbial communities to a changing environment.

Concepts of Biology is designed for the single-semester introduction to biology course for non-science majors, which for many students is their only college-level science course. As such, this course represents an important opportunity for students to develop the necessary knowledge, tools, and skills to make informed decisions as they continue with their lives. Rather than being mired down with facts and vocabulary, the typical non-science major student needs information presented in a way that is easy to read and understand. Even more importantly, the content should be meaningful. Students do much better when they understand why biology is relevant to their everyday lives. For these reasons, Concepts of Biology is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand.We also strive to show the interconnectedness of topics within this extremely broad discipline. In order to meet the needs of today's instructors and students, we maintain the overall organization and coverage found in most syllabi for this course. A strength of Concepts of Biology is that instructors can customize the book, adapting it to the approach that works best in their classroom. Concepts of Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand--and apply--key concepts.