Zooplankton

Abstract: Preface 1 Prologue 2 Water as a Substance 3 Rivers and Lakes - Their Distribution, Origins, and Forms 4 Water Economy 5 Light in Inland Waters 6 Fate of Heat 7 Water Movements 8 Structure and Productivity of Aquatic Ecosystems 9 Oxygen 10 Salinity of Inland Waters 11 The Inorganic Carbon Complex 12 The Nitrogen Cycle 13 The Phosphorus Cycle 14 Iron, Sulfer, and Silica Cycles 15 Planktonic Communities: Algae and Cyanobacteria 16 Plantonic Communities: Zooplankton and their Interactions with Fish 17 Bacterioplankton 18 Land-Water Interfaces: Larger Plants 19 Land-Water Interfaces: Attached Microorganisms, Littoral Algae, and Zooplankton 20 Shallow Lakes and Ponds 21 Sediments and Microflora 22 Benthic Animals and Fish Communities 23 Detrirus: Organic Carbon Cycling and Ecosystem Metabolism 24 Past Productivity: Paleolimnology 25 The Ontogeny of Inland Aquatic Ecosystmes 26 Inland waters: Understanding is Essential for the Future References Appendix Index

Abstract: The use of 15N-labeled compounds to obtain specific uptake rates for the various nitrogen sources available to the phytoplankton makes it possible to separate the fractions of primary productivity corresponding to new and regenerated nitrogen in the euphotic zone of the ocean. Measurements of nitrate uptake as a fraction of ammonia plus nitrate uptake have been obtained from the northwest Atlantic and the northeast Pacific oceans. Mean values range from 8.3 to 39.5%, the former being characteristic of subtropical regions and the latter of northern temperate regions or coastal and inland waters. Nitrogen fixation is also a source of new nitrogen. Rates of nitrogen fixation are found to be as high or higher than nitrate uptake, in some cases suggesting an important role for nitrogen-fixing phytoplankton. The role of zooplankton in regenerating nitrogen as ammonia in the Sargasso Sea is examined theoretically. Probably only about 10% of the daily ammonia uptake by phytoplankton is contributed by the zooplankton living in the upper 100 m.

Abstract: Small plastic detritus, termed “microplastics”, are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7–30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets lade...

Abstract: This paper describes a dilution technique for estimating the micro-zooplankton grazing impact on natural communities of marine phytoplankton. Experiments performed in coastal waters off Washington, USA (October, 1980), yield estimates of micro-zooplankton impact equivalent to 6 to 24% of phytoplankton standing biomass and 17 to 52% of production per day. Indirect evidence suggests that most of this impact is due to the feeding of copepod nauplii and tintinnids; in contrast, non-loricate ciliates, comprising 80 to 90% of numerical abundance, appeared to contribute little to phytoplankton mortality.