SPECIES INVASIONS: Water Hyacinth and Zebra Mussels

By Bianca T. Esposito, NWNL Research Intern
(Edited by Alison M.  Jones, NWNL Director)

Bianca T. Esposito is a Syracuse University senior studying Biology and Economics. Her summer research for NWNL was on biodiversity and water resources. Her past NWNL blogs are:  Wild v Hatchery Salmon; Buffalo & Bison; Papyrus & Phragmites; & Deer & Elephants.

INTRODUCTION

Invasive species are those that threaten to overtake other species.  Whether flora or fauna, native or introduced, invasive species pose aggressive threats to the quality of lakes and ponds. “Introduced species” aren’t necessarily invasive; and “native species” can become invasive. Introduced species that are aggressive to the point of creating potential problems are termed “non-native invasives.” This blog discusses the impacts of two non-native invasive populations: water hyacinth (flora); and zebra mussels (fauna).  

TO WATER HYACINTH

Jones_110805_CAN_0498.jpgWater Hyacinth at the Montreal Botanical Garden, Canada. 

Water hyacinth (Eichhornia crassipes) is a perennial, free-floating aquatic weed, native to South America’s Amazon River, but carried overseas for ornamental use. Today the water hyacinth is considered to be the “world’s worst aquatic weed.” This aggressive, invasive species spreads rapidly over entire surfaces of lakes and ponds and can double its coverage in just two weeks. Yet its ability to withstand drastic fluctuations in flow rates, acidity and low nutrient levels makes it a viable and popular water-garden plant.  

Since imported to North America in 1884, it has invaded the Columbia and Mississippi River Basins, two NWNL case-study watersheds. Also introduced into East Africa, it is present in three NWNL basins:  those of the Omo, Nile and Mara Rivers. Recorded in Egypt as early as the 1890’s, water hyacinth became a “plague” in the late 1900’s. River control schemes, such as dams, barrages and irrigation canals have encouraged its growth and spread. Furthermore, climate change, a combination of higher temperatures and CO₂ fertilization, is significantly increasing water hyacinth proliferation.

IMPACTS TO NATIVE RIVERINE SPECIES

On the positive side, water hyacinth cleans contaminated waters by absorbing large amounts of heavy metals into its tissue. However, once established, its degradation of waterways crowds out an ecosystem’s native species. Ergo, it becomes a “pest species.”

Jones_091002_TZ_1385Water Hyacinth with Papyrus in Masurua Swamp, Tanzania

On Mississippi River waterways, water hyacinth becomes a mesh of dense mats ─ some spanning hundreds of acres of water. These mats cluster and cause a chain reaction that block sunlight from reaching native submerged plants, deplete oxygen in the water and kill aquatic wildlife, including fish. Ultimately, these mats prevent the growth and abundance of phytoplankton and other rooted benthic, aquatic plants that rely on sunlight and release O2. This negatively impacts fisheries, since phytoplankton is the basis of many aquatic food webs.

Kenyan fishermen on Lake Victoria, source of the White Nile Basin, have seen a 45% decrease in fish-catch rates after water hyacinth mats blocked access to fishing grounds, and thus delay delivery to markets. These consequences have increased costs of fishing efforts and materials. This hurts all who rely on fishing, and decreases the quality of fish in local markets.

In sum, the presence of water hyacinth within water bodies means: No Sunlight – No Photosynthesis – No Oxygen – No Fish. Ultimately, through this chain reaction, water hyacinth destroys the native ecosystems it invades.

EXTENDED WATERSHED DAMAGE BY WATER HYACINTH

Jones_091003_TZ_2892.jpgWater Hyacinth with Papyrus in Masurua Swamp, Tanzania

─ Wind, water currents and boat traffic can break off pieces of water hyacinth mats that then  can drift or blow away into new territories.

─ In sub-freezing Mississippi River Basin winters, water hyacinth mats decompose and literally tons of dead plant matter sink at once to the bottom, creating shallower rivers after several years of this build-up.

─ Water hyacinth disrupts critical values and services by blocking boater access; impeding commercial and recreational boat navigation; reducing water flow; and interfering with hydroelectric power generation.

─ Water hyacinth also affects drainage and irrigation canals by clogging intake pumps and  reducing water flow. This causes floods and damage to canal banks. In recreational waters, water hyacinth invasion  negatively impacts anglers, water-skiers and swimmers.

WATER HYACINTH SOLUTIONS

Water hyacinth management costs are close to US$100 million/year in both the US and Africa. Thus, it is clear that prevention is the most effective and cheapest control.

Another approach is to control expansion. This is usually, but controversially, done with low-cost chemical herbicides labeled “For aquatic use,” such as Glyphosate 5,4. However,  application of this herbicide creates decomposition of dead plant material, thus fostering oxygen depletion which kills fish and other aquatic species.  

Other methods of control include mechanically raking and harvesting the plant ─ as well as hand removal, biocontrol insects (such as the Neochetina beetle) and summer drawdowns. When harvesting and removing the plant, it is crucial to not discard it into a natural water way, but rather contain it in protected compost.

INTRODUCTION TO ZEBRA MUSSELS

Zebra_mussels_line_shore_on_Green_Bay_at_Red_River_County_Park_in_Kewaunee_County_Wisconsin.jpgZebra mussels line Green Bay, Red River County Park, WI (Creative Commons)

Zebra mussels (Dreissena polymorpha), native to lakes in southeast Russia, are another non-native invasive species. In the 19th century, zebra mussels accidentally expanded into western Europe, the UK and N. America through trade. They entered N. America in the 1980’s when a trading boat came into the Great Lakes unaware of zebra mussels in its ballast water. Fortunately, invasive zebra mussels have yet to spread to Africa; but it could happen in the near future through trade.

Zebra mussels are the only freshwater bivalves able to attach to hard substrates in high densities. They reside in larger estuaries, inland rivers and lakes, adapting to hard- and soft-bottom habitats with surfaces suitable for attachment. Their entry into new ecosystems occurs through accidental transportation when attached to the bottom of boats. Once attached to a surface, zebra mussels are nearly impossible to remove. However, juvenile zebra mussels, with their ability to move freely in water, pose an additional threat to uncontaminated waters.

In some areas of the Mississippi River, there are as many as 20,000 zebra mussels per square yard. Since 1986, they have invaded 20 states east of the Mississippi River. There is no detection yet of zebra mussels in the NWNL case-study Raritan and Columbia River Basins. According to the State of NJ, “Zebra mussels have not yet been detected in New Jersey waters, but it is probable that invasion will occur in the near future.”  

The Columbia River Basin, as of Aug 6, 2018, is the only major western US watershed not yet invaded by zebra and quagga mussels. Montana’s Flathead Lake, which drains into the Clark and Pend Oreille River tributaries to the Columbia River, is the last barrier against zebra mussels slipping into the the Columbia River system. One means of protection at the lake, and throughout the Columbia watershed, is extensive warning via signage and implementation of inspection stations, such as one on US Highway 93, that pressure-washes contaminated boats if they are found with mussels.

ZEBRA MUSSELS: NATIVE SPECIES IMPACTS & LOSSES

Zebra_mussels_dreissena_polymorpha_on_native_mussel.jpgZebra Mussels growing up a native mussel (Creative Commons)

Since zebra mussels have no natural predators in new ecosystems, they easily and dramatically reduce native species in US and Canadian fishing communities, by consuming and decreasing the amounts of  food traditionally available for native species, such as algae. Zebra mussels also attach themselves to native species, such as crayfish, turtle shells and other mussels.  In limiting the ability of native species to move, feed, breath and breed, they prevent reproduction and threaten their survival, as happened with the native “Higgins eye pearlymussel.”  

EXTENDED WATERSHED DAMAGE BY ZEBRA MUSSELS

Jones_121030_TX_8719.jpgSign warning for invasive Zebra Mussels at Eisenhower State Park, Texas 

In aggregating on hard surfaces, zebra mussels cause economic impacts on municipal, industrial and private water systems. Since they grow in dense colonies, they can clog intake pipes and change the ecology of their new ecosystems. Zebra mussels also damage ecosystem services; change and alter habitat; decrease oxygen concentration when they respirate; modify natural benthic communities and modify nutrient regime. They  negatively impact human health, aquaculture/fisheries, tourism and disrupt transportation. Even outside of the water, this invasive species destroys beaches with its extremely foul smell upon decaying.

Economic costs to manage zebra mussels impacts the Midwest and eastern US annually at an estimated $1 billion dollars. The Great Lakes region alone spends an estimated $500 million/year scrubbing zebra mussels from docks, pipes and intake pumps. While zebra mussels have not yet spread to NJ waterways, management costs hypothetically would run approximately $336 million/ year. If zebra mussels reach the Columbia River Basin their damage could cost hydroelectric facilities alone anywhere from $250 million to $300 million/ year.

ZEBRA MUSSEL SOLUTIONS

Jones_150816_AZ_5638.jpgSign warning boaters of invasive Zebra Mussels in Goose Lake, Arizona

Currently, zebra mussels are routinely removed from raw water systems where they create a bio-fouling nuisance, and are then discarded in landfills. Mechanical removal of attached zebra mussels is done using high-pressure water cleaning and micro-encapsulated BioBullets. Rigorous boating equipment maintenance by all boat owners is critical in stopping the spread of zebra mussels. Signs in most harbors and ports now warn that boats be cleaned with warm soapy water when entering from another body of water. Additionally, boaters are told not to dump water from one body of water into another body of water, since juvenile mussels move freely. Two critical solutions are 1) every boat owner assuming responsibility and 2) signage that spreads awareness of this invasive species.

CONCLUSION:

Clearly invasive species pose major problems to the new habitats they invade, whether flora, such as hyacinth, or fauna, such as zebra mussels.  In N. America and Africa, water hyacinth has hindered the growth of native aquatic flora and phytoplankton, depleting the aquatic food chain. Adult zebra mussels degrade watersheds by clogging irrigation pipes, and crowding out of native species. Additionally, unattached juvenile mussels easily spread this species to uncontaminated waters. Although invasive species can have some beneficial traits to the watersheds they dominate, degradation by water hyacinth and zebra mussels outweighs their benefits. It is imperative to spread awareness on how to prevent the spread of these and other non-native invasive species in order to protect the health of all impacted watersheds.

All photos © Alison M. Jones unless otherwise noted.


Bibliography:

“African Plant may Help Fight Zebra Mussel Scourge.” Wire Reports, accessed on July 24, 2018, via link
Batanouny, K. H. “The Water Hyacinth in the Nile System, Egypt.” Aquatic Botany, accessed on July 23, 2018, via link
Benson, Amy J. “The Exotic Zebra Mussel.” U.S. Fish & Wildlife Service: Endangered Species, accessed on July 24, 2018, via link.
“Case Study: Water Hyacinth.” U.S. Department of State Archive, accessed on July 25, 2018, via link
Diop, S. “Climate Change Vulnerability and Impacts in River Basins and Aquifers Basins in Africa: Analysis of Key Response Strategies.” Accessed on July 24, 2018, via link.
“Dreissena polymorpha (zebra mussel).” CABI, accessed on July 23, 2018, via link.
“Emerging Emvironmental Issues 2013.” United Nations Environment Programme, accessed on July 24, 2018, via link.
Hanson, Erik and Sytsma, Mark.  “Oregon Aquatic Nuisance Species Management Plan.” Center for Lakes and Reservoirs at Portland State University, accessed on July 24, 2018, via link.
“How to Control Water Hyacinth.” AquaPlant – Texas A & M AgriLife Extension, accessed on Sept 25, 2018 by AMJ, via link.
“Idaho Aquatic Nuisance Species Plan.” The Idaho Invasive Species Council Technical Committee, accessed on July 24, 2018, via link.
Jacewicz, Natalie. “Why A Really Big Fish Isn’t Always Good For Business.” National Public Radio, accessed on July 25, 2018, via link
Leposo, Lilian. “Flower Power Threatens Kenya’s Lake Victoria.” CNN, accessed on July 23, 2018, via link.
Madsen, John D and Robles, Wilfredo. “Water Hyacinth.” Mississippi State University, Geosystems Research Institute, accessed on July 23, 2018, via link.
McLaughlan, Claire. “Making the Best of a Pest: The Potential for Using invasive Zebra Mussel Biomass as a Supplement to Commercial Chicken Feed.” Environmental Management, accessed on July 24, 2018, via link.
Neal, Wes. “Beautiful Water Hyacinth yields long-term damage.” Mississippi State University Extension Service, accessed on July 23, 2018, via link.
Ouellet, Nicky.  “Flathead Lake Healthy, Biological Station Director Says” Montana Public Radio, Aug 6, 2018. Accessed Sept 25, 2018 by amj, via link.
Reilly, Patrick. “At Columbia River’s doorstep, an uneasy lookout for invasive mussels.” The Oregonian/OregonLive, accessed on July 24, 2018, via link
Scott, Tristan.  “Biological Station: No Invasive Mussels Detected in Flathead Lake.”  Flathead Beacon, Feb 17, 2017. Accessed Sept 25, 2018 by amj via link.
Waltham, N. J. “Aerial Herbicide Spray to Control Invasive Water Hyacinth (Eichhornia crassipes): Water Quality Concerns Fronting Fish Occupying a Tropical Floodplain Wetland.”Sage Journals, accessed on July 25, 2018, via link
“Water Hyacinth.” AquaPlant – Texas A & M AgriLife Extension, accessed on July 23, 2018, via link.
“Water Hyacinth.” Southeast Exotic Pest Plant Council, accessed on July 23, 2018, via link.
“Water Hyacinth.” US Department of Agriculture, accessed on July 23, 2018, via link.
“Water Hyacinth Control.” Lake Restoration Incorporated, accessed on July 23, 2018, via link.
“Zebra Mussels.” Reduce Risks from Invasive Species Coalition, accessed on July 23, 2018, via link.
“Zebra Mussels.” New Jersey Department of Environmental Protection, accessed Aug 9, 2018, via link
“Zebra Mussels are Taking Over our River!” 1 Mississippi, accessed on July 24, 2018, via link.
“Zebra Mussels Dying in Mississippi River.” United Press International, accessed on July 24, 2018, via link.

Aswan High Dam Leaves an Environmental Legacy

by Joannah Otis for No Water No Life

This is the second our blog series on “The Nile River in Egypt” by NWNL Researcher Joannah Otis, sophomore at Georgetown University. Following her blog “Finding Hapi-ness on the Nile,” this essay addresses perhaps the greatest elements of change created thus far by humans along the Nile. [NWNL has completed documentary expeditions to the White and Blue Nile Rivers, but due to current challenges for photojournalists visiting Egypt and Sudan, NWNL is using literary and online resources to investigate the availability, quality and usage of the Nile in those regions.]

Aswan_DamAswan Dam on the Nile River in Aswan, Egypt

Background on Aswan High Dam

The Nile River snakes south to north for 4,160 miles through ten North African countries until it reaches the Mediterranean Ocean.1 Its path is interrupted only by the great Aswan High Dam, which has brought both good and bad to the Egyptian people. Towering 364 feet tall and stretching 12,565 feet along its crest, the Aswan High Dam is impressive.2 This dam was opened in 1971 after a decade of construction and seeking funds from the Soviet Union.3 Its transboundary reservoir, Lake Nasser, which backs up into Sudan for 300 miles, holds nearly two years’ worth of water from the Nile River.

Benefits of the Aswan High Dam & Lake Nasser

The High Dam, replacing a 1902 Low Dam, annually generates more than 10 billion kilowatt hours of electricity, facilitating Egypt’s path to industrialization. This new dam also marked a major shift in Egypt’s agricultural prospects. Previously, Nile River Basin farmers were forced to depend on fickle seasonal flooding, which could bring appropriate levels of water one year and often completely washed away soil the next. Such unpredictability made it hard to grow a reliable crop; and the Nile’s single flooding season precluded farmers from having more than one harvest per year.

Lake Nasser’s surplus of water has well served the irrigation needs of Egypt and Sudan, since water availability is especially critical, given Egypt’s growing population and increasing water needs. (NB:  NWNL is studying these trends that portend dire water scarcity in the near future.) The Aswan Dam now allows for two to three crop cycles annually.  Nearby aquifers are inundated by increased amounts of water due to year long, rather than seasonal irrigation.  Water levels are carefully monitored and extra water is saved for times of drought. There has been huge economic benefit to the fact that the dams has allowed Egypt to triple the output of its most important and profitable crops, wheat and cotton.5  

Lake-nasserLake Nasser in Egypt.

Thus, the Aswan High Dam created a new future of irrigation water, flood control and electricity – but came with disconcerting drawbacks. Its story and continued influence on the Nile River illustrate how human ingenuity can inadvertently take a toll on the environments and ecosystems we so rely on.  The degradation of Nile ecosystems and the influx of increasing chemical runoff are reminders of the negative impacts that infrastructure, intended to improve quality of life, can have on nearby environments and habitats for all species, including humans.

Consequences of the Aswan High Dam & Lake Nasser

While Lake Nasser reservoir has allowed for controlled downstream flows into northern Egypt, that backlog of Nile water forced the relocation about 100,000 people to other lands in Sudan and Egypt.6 Abu Simbel Temple and 22 historical structures fortunately were moved under UNESCO’s watchful eye, yet Buhen Fort, the Fadrus Cemetery and other archeological sites (whose relocation would have been too costly) were submerged.

Stagnant waters in Lake Nasser have threatened the health of people using or residing near the Nile River waters. Downstream, the dam promotes the presence of schistosomiasis, a parasitic disease also known as bilharzia or “snail fever.” Schistosomiasis kills more than 200,000 Africans annually; and 20 million sufferers develop disfiguring disabilities from complications, kidney and liver diseases, and bladder cancer.

Egyptian_harvest.jpgTomb Painting of Peasants Harvesting Papyrus

Seasonal flooding once brought thick layers of dark silt to farms, which farmers used a natural fertilizer. Unfortunately, the Aswan High Dam almost completely blocks the movement of nutrient-rich sediment downstream. (NB:  NWNL has seen similar impacts of Ethiopia’s new Gibe Dams, ending 6,000 years of flood-recession agriculture practiced by pastoralists in the Lower Omo River Basin.) As rich Upper Nile sediments collected behind the dam, Egyptian farmers resorted to toxic chemical fertilizers that drain into the Nile. These pollutants can cause liver disease and renal failure in humans.7 

Farming phosphates running into the river increase algae growth. Algae blooms, elicited by excess nutrients (eutrophication), produce cyanotoxins, which affect the health of fish and may poison humans.At the same time, fish populations no longer benefit from nutrients that used to be in upstream Nile sediments. Aquatic species in the Mediterranean Sea near the Nile Delta have suffered similarly from decreased natural nutrients and increased chemicals.9

Riverbanks also suffer from a lack of replenishing sediments as their erosion continues unchecked.  Prior to the dam’s construction, the average suspended silt load was 3,000 parts per million (ppm). Post-construction silt levels have declined to 50 ppm.10 Further downstream, the Nile Delta suffers from a lack of silt replenishment. [NB:  NWNL has documented parallel deltaic losses and damage in the U. S., as  levees along the Mississippi River withhold sediment that used to rebuild storm erosion in the Mississippi Delta.]

Silt-free water along with a lower current velocity and steady water levels have enabled invasive aquatic weeds to infest the Nile River and its irrigation canals. Large volumes of aquatic weeds, water hyacinths in particular, create stagnant water conditions, impair water flow, provide breeding grounds for malaria-carrying mosquitoes and prevent the passage of boats whose propellers become clogged with invasive weeds.  Prior to the dam’s construction, these weeds were unable to flourish due to the Nile’s varying water levels and the force of its flow.11

Eichhornia_crassipes_C.jpgWater Hyacinth  (Credit: Wouter Hagens)

Erosion in the Nile Delta is especially threatening because it has led to saltwater intrusion.   (NB: Again, this is another issue also occurring in the Mississippi River Delta.)  Increased groundwater salinity from the encroaching Mediterranean Sea is decreasing cotton and rice yields.12 Additionally, fertilizers have further heightened saline levels.13

Beyond Aswan:  Footnote by NWNL Director Alison Jones

In 2009, Egypt was the most populous, agricultural and industrial country in the Nile Basin.14 The Aswan Dam has been a major factor in this march by Egypt to progress and prosperity.  However, just as the Aswan Dam came with a price – so will the upstream Grand Renaissance Dam, now under construction in Ethiopia on the Blue Nile River.  It is likely the impacts of this new Ethiopian dam – the largest ever on the African continent – will be even more consequential to Egypt than those of the Aswan High Dam.  It seems a new chapter is about to be written regarding settlement of transboundary conflicts spawned from disputes over dam impacts and upstream-downstream water rights.

Sources

1“Nile River Facts.” Africa Facts. Web. 2017
2Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
3Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
4Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 600
5Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. 2012. p 389
6Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
7Theroux, Peter. “The Imperiled.” National Geographic Magazine. January 1997.
8El-Sheekh M. “River Nile Pollutants and Their Effect on Life Forms and Water Quality,” in “The Nile.” (Dumont H.J, Monographiae Biologicae, Vol 89. Springer, Dordrecht)
9Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. P 389. 2012.
10Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. P 385. 2012.
11El-Shinnawy, Ibrahim A.; Abdel-Meguid, Mohamed; Nour Eldin, Mohamed M.; Bakry, Mohamed F. “Impact of Aswan High Dam on the Aquatic Weed Ecosystem.” Cairo University. September 2000. p 535-538.
12Theroux, Peter. “The Imperiled.” National Geographic Magazine. January 1997.
13World Wildlife Foundation. “Nile Delta flooded savanna.” Web. 2017.
14El-Sheekh M. “River Nile Pollutants and Their Effect on Life Forms and Water Quality,” in “The Nile.” (Dumont H.J, Monographiae Biologicae, Vol 89. Springer, Dordrecht)
All photos used based on fair use of Creative Commons and Public Domain.

Even invasive species can be beautiful

Water hyacinth (Eichhornia crassipes) is one of the world’s worst aquatic weeds. It is characterized by rapid growth rate, extensive reproductive output and broad environmental resistance. It creates dense mats of vegetation that restrict oxygen in water, causing deterioration in water quality, fish mortality and declining biodiversity. A healthy acre of the plant can weigh 200 tons! These floating masses block waterways and harbors, costing millions of dollars of damage every year.
Water hyacinth grows in lakes, estuaries, wetlands, rivers, dams, and irrigation channels on every continent except Antarctica.

Screen Shot 2014-12-19 at 1.45.53 PM– Posted by Jasmine Graf, NWNL Associate Director