All Photos © Alison M. Jones.
NWNL focuses on freshwater availability, quality and usage. Oceans are also critical to the hydrologic cycle as rivers flow into oceans via estuaries ranging from bays, gulfs, lagoons, bayous, inlets, sounds and harbors.
Mountain ice fields and underground aquifers capture and store rain, ice, vapor, fog and snow. Water in these reservoirs seeps into rills, brooks and streams which become rivers. Those waterways drain almost 90% of our terrestrial lands before they spill into estuaries or deltas, where freshwater mingles with saltwater before spilling into the oceans. These transitional saline estuaries, deltaic wetlands and shorelines are very dynamic tidal elements of the hydrologic cycle, often containing ecologically important wetlands and marshes sustained by nutrient-rich mixes of fresh and marine water critical to the health of aquatic flora and fauna.
In these estuaries, ocean, river and coastal shoreline biodiversity overlaps. These ecosystems are often called the ‘nurseries’ of our world’s fisheries. Many ocean fish return to brackish estuarine water or upstream fresh riverine water to spawn and rear their fry. Anadromous salmon, sturgeon and alewives swim back and forth hundreds of miles from deep seas to woodland tributaries. Sea turtles lay their eggs on sandy shores. Sea mammals supervise their juveniles on sandy shores. Migratory birds rest on sandy shores having flown many thousands of miles.
Seventy percent of the US population resides on or close to our estuaries. Most industry, ports and 80% of our largest cities are also dependent on our estuaries that provide fresh water, food, transportation and recreation. As well, they nurture cultural and spiritual traditions.
But many estuaries are now often sick or dead.
Industrial pollutants, agricultural outputs and human sewage degrade our rivers and estuaries, causing eutrophication and coastal hypoxic zones. Extreme climate events such as droughts and floods significantly alter water flows into our estuaries.
Deforestation presents a double whammy by exacerbating destructive flooding and causing erosion and sedimentation of rivers and wetlands. Urban development and its impermeable surfaces increasingly produce storm-water runoff full of pollutants and raw sewage overflows. Predicted sea level rise will increase estuaries’ salinity levels, drastically altering their ecological functions.
We must control carbon emissions, pollution, development and resource extraction for the sake of oceans, as well as rivers and estuaries. We must more sustainably manage upstream resources in order to protect downstream estuaries and oceans. Some estuaries are now either completely or nearly gone, due to damming and heedless upstream water consumption that ignores downstream needs or rights. Since agriculture consumes 70% or more of our freshwater resources, we must improve irrigation efficiency and plant more drought-tolerant crops. Herbicides, pesticides and chemical runoff into our waters must be restricted. If we do this, our rivers and oceans will be much healthier.
Many glacial deposits, accumulated over the eons, are predicted to melt away forever within a few decades due to global warming. Likewise, our aquifers are being drained much faster than they can ever be re-filled. Human disregard for the importance of the critical “savings banks” of our fresh-water reserves puts the health of our rivers and oceans at alarming risk. For the sake of our rivers and oceans, we can and must reduce water consumption and institute aggressive plans for water recycling.
Wetland ecosystems support fisheries and provide flood regulation, groundwater recharge, silt absorption, habitat filtration, sustenance provision, carbon sequestration, climate regulation, recreation and cultural aesthetic and spiritual values. The EPA includes these “biological supermarkets” among the world’s most productive ecosystems, in the same league as coral reefs and rainforests.
Our rivers feed oceans with nutrients, however they also disperse polluted runoff from residential, agricultural and urban areas into our oceans. It often was casually said that “dilution is the solution to pollution.” But that principle doesn’t completely protect our oceans, tidal marshes or wetlands from the plastics and “forever” pollutants.
According to reports from NOAA and US Fish and Wildlife, coastal watersheds in the continental United States lost about 360,720 acres of wetlands from 2004 to 2009 – an average of 80,000 acres a year, equal to losing 7 football fields per hour. That was a 25% increase over the previous 6 years. Since freshwater wetlands in upper watersheds support estuaries, this affects nearly 50% of commercially harvested fish and shellfish and 80% of the U.S. recreational catch.
Climate change and sea level rise also pose risks to wetlands found at the mouth of our rivers. A recent study claims that the Mississippi River Delta has passed the tipping point and will thus lose its barrier islands that protect New Orleans from increasingly damaging storms.1Mississippi River Delta marshes have Hit a Tipping Point, Study Finds All estuaries are susceptible to climate change impacts. We should plan mitigating adaptations accordingly and quickly protect and salvage their remaining wetlands, islands, shores and biodiversity.
For our oceans to be healthy, our rivers and estuaries must be healthy. All the threats discussed above are induced by humans. Thus, it is critical that marine and riverine scientists, stewards and stakeholders coordinate protection of all of our planet’s waters – from mountain headwaters and tributaries, to downstream rivers and estuaries, to oceans.
Bays, gulfs and coastal shorelines are where fishermen, who sail out into deeper waters, meet inland farmers who cart produce from their fields to boats. Just as they bridge marine and fresh water ecosystems, so should scientists, students of hydrology and stewards. During World Oceans Week, let’s also focus on the sources of oceanic water: our estuaries, deltas and rivers. Loren Eisley wrote, “If there is magic on this planet, it is contained in water.” Let’s keep that magic in our hydrologic cycle.
“Dammed If We Don’t,” by Yvon Chouinard. http://www.patagonia.com/us/patagonia.go?assetid=67738
Mississippi River Delta Marshes Have Hit a Tipping Point, Study Finds,” Published by E360 and the Yale School of Forestry & Environmental Studies, May 26, 2020. https://e360.yale.edu/digest/mississippi-river-delta-marshes-have-hit-a-tipping-point-study-finds
“Patagonia Rising.” https://www.youtube.com/watch?v=tW8fo4z2al0