Dinoflagellates are common unicellular organisms found in all types of aquatic ecosystems and are important contributors to freshwater ecosystems as significant primary producers of biomass. Despite increasing interest in the biology of living and fossil dinoflagellates, there has been no compilation of dinoflagellate species found in North America since 1934, and no keys to species.
Freshwater Dinoflagellates of North America download pdf
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Following an introductory section on the biology, morphology, and ecology of freshwater dinoflagellates, the species are presented in a field guide format with distribution maps, written descriptions emphasizing notable features, line drawings, and black-and-white and color micrographs.
Subtropical estuaries worldwide face increased pressure on their ecosystem health and services due to increasing human population growth and associated land use/land cover changes, expansion of ports, and climate change. We investigated freshwater inflows (river discharge) and the physico-chemical characteristics of Galveston Bay (Texas, USA) as mechanisms driving variability in phytoplankton biomass and community composition between February 2008 and December 2009. Results of multivariate analyses (hierarchical cluster analysis, PERMANOVA, Mantel test, and nMDS ordination coupled to environmental vector fitting) revealed that temporal and spatial differences in phytoplankton community structure correlate to differences in hydrographic and water quality parameters. Spatially, phytoplankton biomass and community composition responded to nutrient loading from the San Jacinto River in the northwest region of the bay (consistent with nutrient limitation) while hydraulic displacement (and perhaps other processes) resulted in overall lower biomass in the Trinity River delta (northeast region). The influence of inflows on phytoplankton diminished along a north to south gradient in the bay. Temporally, temperature and variables associated with freshwater inflow (discharge volume, salinity, inorganic nitrogen and phosphorus concentrations) were major influences on phytoplankton dynamics. Dissolved inorganic nitrogen: phosphorus (DIN:DIP) ratios suggest that phytoplankton communities will be predominately nitrogen limited. Diatoms dominated during periods of moderate to high freshwater inflows in winter/spring and were more abundant in the upper bay while cyanobacteria dominated during summer/fall when inflow was low. Given the differential influences of freshwater inflow on the phytoplankton communities of Galveston Bay, alterations upstream (magnitude, timing, frequency) will likely have a profound effect on downstream ecological processes and corresponding ecosystem services.
HA species comprise only a small component of the phytoplankton community, and their individual responses to climate variation and change can differ from that of the phytoplankton community as a whole. In the ocean, the most important HA and their poisoning syndromes (in parentheses) are diatoms from the genus Pseudo-nitzschia (amnesic shellfish poisoning), and species of dinoflagellates from the genera Alexandrium, Pyrodinium, and Gymnodinium (paralytic shellfish poisoning), Karenia (neurotoxic shellfish poisoning, and aerosolized Florida red tide respiratory syndrome), Dinophysis and Prorocentrum (diarrhetic shellfish poisoning), and Gambierdiscus (ciguatera fish poisoning). In freshwater, the most important HABs are caused by certain species of cyanobacteria (blue green algae) from the genera Anabaena, Microcystis, and Aphanizomenon (cyanobacterial poisoning) [16]. In both marine and freshwater systems, for humans and other animals, exposure to HA toxins results from eating contaminated fish or shellfish, drinking contaminated water, inhaling contaminated aerosol, or by contacting contaminated water.
An example of a dataset which could be used to study global change and HABs in the future is the Continuous Plankton Recorder (CPR) Survey which provides near unbroken monthly coverage of transects across the northeast Atlantic and North Sea from 1946. Most of the region sampled by the CPR is further than 1 km offshore in open ocean waters, and is therefore relatively unaffected by anthropogenic eutrophication that is generally concentrated along the coast [11]. Even though most HA species are too small to be captured by the CPR, changes in the relative abundances of functional groups of phytoplankton (i.e., diatoms and dinoflagellates), and of some larger HA species, such as Prorocentrum and Dinophysis spp., can be assessed. Using this long-term dataset, the influence of the North Atlantic Oscillation (NAO) on the spatial distribution of these larger HA species was determined independently from the effects of anthropogenic eutrophication [11]. Distinguishing these effects lends credence to predictions of climate change impacts on HABs based on their response to warm phases of large-scale patterns of climate variability. Monitoring programs with comparable spatial and temporal resolution to the CPR, but specifically targeting smaller size fractions of plankton containing HA species, will be required to elucidate climate change impacts in the future.
Pogonias is known from two extant species with an antitropical distribution in the Western Atlantic (P. cromis from the northwestern Atlantic and P. courbina from the southwestern Atlantic), which are principally marine but may enter into brackish but not freshwater. However, the related monospecific genus Aplodinotus is today exclusively found in freshwater in southeastern North America (Schwarzhans, 1993). We consider Pogonias tetragonus to possibly represent an extinct freshwater clade of the group in the Pebas Wetland System similar to Aplodinotus grunniens of North America. 2ff7e9595c
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