World Water Day (March 22, 2019)

March 22, 2019

World Water Day 3

By Harry Seely, BSc student

Today we celebrate world water: we recognize the importance of the most fundamental molecular compound for life on our planet, one that defines every species, ecosystem and landscape.  While water is crucial for human health and is recognized as a basic human right by the United Nations, water is just as vital to every organism on planet earth.  For every organism, water drives metabolism in the form of photosynthesis and respiration, transports nutrients, and acts as the versatile “universal solvent”.  Not only does water help build life and sustain it, water hosts an incredible number of species.  The ocean holds roughly a quarter of life on earth (226,000 eukaryotic species) and an estimated 91% of its biodiversity has not yet been categorized (1,2).  Additionally, while freshwater habitat constitutes less than 1% of the earth’s surface, it supports 10% of all known species and roughly a third of all vertebrate species (3).

Sadly, the aquatic ecosystems of the world are under threat and numerous influences are becoming more and more detrimental to marine and freshwater biodiversity.  Many different marine species are currently threatened or near threatened as described by the IUCN including 40% of sharks, 47% of corals and 6 out of the 7 species of marine turtles (although many taxonomic groups have more than half of their species categorized as data deficient) (4).  Freshwater species are also facing large decreases in abundance, especially when compared to terrestrial species. Notably, 32% of the world’s amphibian species are now threatened with extinction and there is an extinction rate of freshwater species in North America estimated to be as high as 4% per decade, a rate which is five times higher than species losses estimated for any terrestrial habitat (5,6).  Threats to marine and freshwater biodiversity are numerous and include climate change, overfishing and exploitation, pollution and litter, invasive species and flow modification in streams and rivers (5,7). 

The dire situations faced in aquatic ecosystems across the globe demand significant research initiatives in order to find both causes and solutions to these problems. Fortunately, there is substantial research being conducted worldwide in an effort to solve the biodiversity crises that threatens aquatic wildlife.  There are many BiRN faculty members that are actively researching water, the ecology of marine and freshwater ecosystems, and how these systems can retain their diverse wildlife in the face of looming adversity brought on by anthropogenic influence and global change.  Dr. Robert McLaughlin is involved in the challenging project of invasive Atlantic sea lamprey management in the Great Lakes.  Dr. Mclaughlin is currently conducting research on innovative ways to selectively sort sea lamprey out of streams and tributaries to reduce their population size (8).  Dr. Kevin McCann has conducted recent research investigating biomass scaling in aquatic biomes and how this relates to predator prey interactions; his work ultimately helps shed light on the structure and function of aquatic ecosystems (9).  Dr. Robert Hanner has done research utilizing DNA barcoding to better understand the bioaccumulation of natural toxins being moved through Pacific marine ecosystems (10).  Other members of BiRN who are also contributing to research efforts focused on solving the modern challenges faced by aquatic ecosystems include Drs. John Fryxell, Andrew MacDougall, Ryan Prosser, Jana Levison, and Neil Rooney.  Please visit the Research Publications page for more information on recent studies on water and aquatic ecosystems by these and other BiRN members.




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  2. Mora C, Tittensor DP, Adl S, Simpson AGB, Worm B. How many species are there on earth and in the ocean? PLoS Biol. 2011;9(8):1–8.
  3. Strayer DL, Dudgeon D. Freshwater biodiversity conservation: recent progress and future challenges. J North Am Benthol Soc [Internet]. 2010 Mar 1;29(1):344–58. Available from:
  4. Hilton-Taylor C, Pollock C, Chanson J, Butchart S, Oldfield T, Katariya V. State of the world’s species. In: Vié J.-C., Hilton-Taylor C. and Stuart S.N. (eds.) Wildlife in a Changing World—An Analysis of the 2008 IUCN Red List of Threatened Species [Internet]. 2008. 15-41 p. Available from:
  5. Dudgeon D, Arthington AH, Gessner MO, Kawabata ZI, Knowler DJ, Lévêque C, et al. Freshwater biodiversity: Importance, threats, status and conservation challenges. Biol Rev Camb Philos Soc. 2006;81(2):163–82.
  6. Ricciardi A, Rasmussen JB. Extinction Rates of North American Freshwater Fauna. Conserv Biol [Internet]. 1999 Oct 23;13(5):1220–2. Available from:
  7. Gray J. S. Marine biodiversity: Patterns threats and conservation needs. Biodivers Conserv [Internet]. 1997;175:153–75. Available from: //a1997wl15900010
  8. Rahel FJ, McLaughlin RL. Selective fragmentation and the management of fish movement across anthropogenic barriers. Ecol Appl. 2018;28(8):2066–81.
  9. Hatton IA, McCann KS, Fryxell JM, Davies TJ, Smerlak M, Sinclair ARE, et al. The predator-prey power law: Biomass scaling across terrestrial and aquatic biomes. Science (80- ) [Internet]. 2015 Sep 4;349(6252):aac6284. Available from:
  10. Braid HE, Deeds J, DeGrasse SL, Wilson JJ, Osborne J, Hanner RH. Preying on commercial fisheries and accumulating paralytic shellfish toxins: a dietary analysis of invasive Dosidicus gigas (Cephalopoda Ommastrephidae) stranded in Pacific Canada. Mar Biol [Internet]. 2012;159(1):25–31. Available from: