Ecosystem services provided by marine and freshwater phytoplankton

Phytoplankton, the ecological group of microalgae adapted to live in apparent suspension in water masses, is much more than an ecosystem’s engineer. In this opinion paper, we use our experience as phytoplankton ecologists to list and highlight the services provided by phytoplankton, trying to demonstrate how their activity is fundamental to regulate and sustain Life on our Planet. Although the number of services produced by phytoplankton can be considered less numerous than that produced by other photosynthetic organisms, the ubiquity of this group of organisms, and their thriving across oceanic ecosystems make it one of the biological engines moving our biosphere. Supporting services provided by phytoplankton include almost half of the global primary and oxygen production. In addition, phytoplankton greatly pushes biogeochemical cycles and nutrient (re)cycling, not only in aquatic ecosystems but also in terrestrial ones. In addition, it significantly contributes to climate regulation (regulating services), supplies food, fuels, active ingredients and drugs, and genetic resources (provisioning services), has inspired artistic and craft works, mythology, and, of course, science (cultural services), and much more. Therefore, phytoplankton should be considered in all respects a true biosphere’s engineer

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28 S rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.Alliance of German Science Organizations///AlemaniaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28 S rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.</p

Species-based classification reveals spatial processes of phytoplankton meta-communities better than functional group approaches: a case study from three freshwater lake regions in China

Phytoplankton communities respond rapidly to environmental selection at a given locality, and they are also shaped by spatial processes at certain scales. The extracted effect of environmental selection and spatial processes may vary if different classification approaches are applied to phytoplankton and the spatial scales. In this study, summer phytoplankton of 43 lakes from three major lake regions in China were investigated and phytoplankton were classified with three approaches: taxonomy of species, habitat template-based functional groups, and morphology-based functional groups. Within a single lake region, the pattern of phytoplankton meta-community was significantly explained by environmental but not by spatial variables. In a larger scale covering all the three lake regions, both environmental and spatial variables explained the variance of the phytoplankton community, but the spatial variables were detected only by classification with species, and only the environmental variables were detected with phytoplankton functional groups. This study revealed that although vegetative populations of different species sorted into the same functional group have common response to environmental changes, their dispersal abilities, mechanisms, and strategies might differ markedly and therefore the species-specific approach cannot be disregarded when studying phytoplankton patterns at spatial scales

Succession of phytoplankton functional groups regulated by monsoonal hydrology in a large canyon-shaped reservoir

Liuxihe reservoir is a deep, monomictic, oligo-mesotrophic canyon-reservoir in the subtropical monsoon climate region of southern China. Phytoplankton functional groups in the reservoir were investigated and a comparison made between the succession observed in 2008, an exceptionally wet year, and 2009, an average year. The reservoir shows strong annual fluctuations in water level caused by monsoon rains and artificial drawdown. Altogether 28 functional groups of phytoplankton were identified, including 79 genera. Twelve of the groups were analyzed in detail using redundancy analysis. Because of the oligo-mesotrophic and P-limited condition of the reservoir, the dominant functional groups were those tolerant of nutrient (phosphorus) deficiency. The predominant functional groups in the succession process were Groups A (Cyclotella with greatest axial linear dimension 10 mu m), L(O) (Peridinium),L(M) (Ceratium and Microcystis), E (Dinobryon and Mallomonas), F (Botryococcus), X(1) (Ankistrodesmus, Ankyra, Chlorella and Monoraphidium) and X(2) (Chlamydomonas and Chroomonas). The development of groups A, B and L(O) was remarkably seasonal. Group A was dominant during stratification, when characteristic small size and high surface/volume ratio morphology conferred an advantage. Group L(O) was dominant during dry stratification, when motility was advantageous. Group B plankton exhibited a high relative biomass during periods of reduced euphotic depth and isothermy. Groups L(M), E, F, X(1) and X(2) occasionally exhibited high relative biomasses attributable to specific environmental events (e.g. drawdown, changes in zooplankton community). A greater diversity of phytoplankton functional groups was apparent during isothermy. This study underscores the usefulness of functional algal groups in studying succession in subtropical impoundments, in which phytoplankton succession can be significantly affected by external factors such as monsoonal hydrology and artificial drawdown, which alter variables such as retention time, mixing regime and thermal structure and influence light and nutrient availability. (C) 2011. Elsevier Ltd. All rights reserved

Chapter 14 - The Impact of the Changing Climate on Seasonal Dynamics of Phytoplankton

In this chapter, we use results acquired from a range of different European lakes to explore the potential effects of climate change on the seasonal development and the composition of phytoplankton. The time-series analysed are amongst the longest available in the region. Some of the lakes studied in CLIME have been sampled at weekly or fortnightly intervals for more than fifty years. These sites also cover a range of lake types from shallow to deep, small to large, and oligotrophic to eutrophic. Geographically the lakes represent the Nordic, Atlantic, Central European and Alpine climatic and eco-regions. Besides specific CLIME sites, examples from other lakes are included where appropriate. Here, we concentrate our attention on the changes observed over the last 30 years, a period of particularly rapid change in most of the catchments selected for study. Issues that greatly complicate the analysis of long-term climate change impact on lakes are the complementary trends of eutrophication and re-oligotrophication. These management-related problems can, however, be minimized by using appropriate de-trending techniques and drawing comparisons with model simulations.JRC.DDG.H.5-Rural, water and ecosystem resource