January 2022
Sticky Mussels

Invasive freshwater zebra mussel (Dreissena polymorpha) and quagga mussel (Dreissena rostriformis bugensis) continue to spread rapidly across North American waterways. They anchor themselves on ships/boats, take up residence in marinas, and clog pipes and water outflow systems. Much of their rapid dispersal is thanks to their ability to firmly attach to a wide variety of materials quickly. This attachment is facilitated by the byssus, a collection of proteinaceous threads each terminated by an adhesive plaque. These treads are a few millimeters long and as thin as a human hair.

To better understand the adhesion mechanics, researchers measured the adhesive strength of individual quagga and zebra mussel byssal plaques on smooth substrates with varying degrees of hydrophobicity, such as glass, PVC, and PDMS. They did this by measuring the adhesive strength and adhesion energy of the plaque-substrate connection through single-plaque tensile detachment testing. Under the stereomicroscope, individual byssal strands (attached to a substrate) were loaded into a custom-built apparatus equipped with a force gauge and were displaced vertically until the strand detached.

As expected, the mussels adhered more strongly to glass than to the PVC or PDMS. Glass is a hydrophilic (water-attracting) material that is similar to rocks and other natural substrates preferred by mussels. PDMS repels water and is often applied to boat hulls to prevent biofouling. Zebra mussels adhered more strongly and more frequently the PVC and PDMS compared to the quagga mussels. This suggests that factors such as hydrophobicity and substrate stiffness may elicit a different response for zebra and quagga mussels, and that zebra mussels display a more universal adhesion than quagga mussels The results also revealed that freshwater mussel plaques adhere with strengths comparable to marine mussels despite differences in protein composition.

Researchers hope their findings will lead to the development of materials or coatings that could keep invasive mussels from clogging water intake pipes or adhering so successfully to the bottom of boats. Things like this could reduce the necessity of chemical treatments, which can kill everything nearby, not just the mussels. They also hope having a greater understanding of why mussels stick so efficiently could help design things like non-toxic biodegradable glues that can be used in wet conditions.

Read more about the research: James et al., 2021


Shopping cart completely encrusted after just a few months in zebra mussel infested water. James F. Lubner. University of Wisconsin Sea Grant InstituteShopping cart that is completely encrusted with zebra mussel (Dreissena polymorpha) after just a few months in infested water. Credit: James F. Lubner, University of Wisconsin Sea Grant Institute.

forceps lined up on plaque-substrate to run a single-plaque tensile detachment testForceps lined up on mussel plaque-substrate to run a single-plaque tensile detachment test. Credit: James et al., 2021.


Antarctica May Be in Trouble

Antarctica and the Southern Ocean remain the least invaded marine regions on the planet, but will they be able to stay that way? Recent research has indicated that Antarctica is much more globally connected than previously thought.

Antarctica is connected to all regions of the globe through an extensive network of ships active in tourism, fishing, research, and supply transport. Shipping activity in the area has increased 10-fold since the 1960s, increasing the potential for exposure to invasive, non-native species that could threaten the stability of its pristine environment. Since Antarctica and the Southern Ocean native species have been isolated for 15-30 million years, there is no telling what economic or environmental impact the introduction of new species would have on the region. Non-native species such as mussels, barnacles, crabs, algae, amiphods (shrimp-like crustaceans), bryozoans, hydroids (like anemones or jellyfish) and seaweed can be picked up from anywhere along a ships voyage and attach themselves to the hull, in a process called 'biofouling'. The hull of a ship is often only cleaned once a year. Imported cargo, vehicles and fresh food supplies can hide species, such as insects or rodents, and visitors can carry seeds attached to their shoes and clothing.

Introduced organisms would have to be able to tolerate the extreme climate in order to become established, but there are those that could succeed in this task. Researchers are most worried about the movement of species from one pole to the other, since these individuals would already be cold-adapted. Mussels and shallow-water crabs pose the most risk of upsetting the environment because there are none found in Antarctica. Mussels could create “mussel beds”, which could outcompete local species or create a new habitat for more non-native species. Crabs would represent a new kind of predation that local species might not be able to defend against. Mosses, hair grass, and pearlwort could thrive on the blanket of peat and partly decomposed vegetable matter that covers much of the land not covered in ice, transforming the peat into soil which produces nitrogen and other waste products.

The longer a boat is in port, the greater the likelihood of a non-native species to be introduced. Researchers have already detected some invasive grasses and insects, such as a species of flightless midge (Eretmoptera murphyi) on Signy Island, that are free-living in the region that were likely introduced through human activities. An evaluation of the Antarctic Peninsula region allowed researchers to compose a list of 103 species (not yet introduced to the region) that present a risk of invasion, 13 of which were considered high risk. Read more here.

Read more about the ship traffic that connects Antarctica to worldwide ecosystems here.

global port to port shipping mapA global port-to-port shipping map that shows a network of ships that visited Antarctica between 2014 and 2018. The PNAS study showed that shipping connected Antarctica to ports from around the world in addition to known gateway ports closest to the frozen continent. Credit: David Aldridge and Jacqueline Garget.

invasive species on hull of ship heading to AntarcticaStalked and acorn barnacles, green algae and caprellid amphipods (small marine crustaceans) on a ship that visited Antarctica and the Arctic. Credit: Arlie McCarthy.

Homogenization of Plant Communities

There are many major drivers that change biological communities due to human activity, such as species extinction, the introduction of non-native species, climate change, and pollution. A recent publication examined how plant communities are responding to the biological community and to global change, especially since the bridging of the eastern and western hemispheres roughly 500 years ago.

A database of over 200,000 plant species worldwide was examined to demonstrate how species extinctions and non-native invasive plants reorganize plant communities in the Anthropocene, the current geological age dominated by human activity. Extinction events and the naturalization of non-native species is causing homogenization to occur, which in turn is leading to a reduction in species and evolutionary differences. Homogenization is the gradual replacement of native species by locally spreading non-native species, and can have negative impacts on important ecosystem functions. By looking at the global distribution of plant occurrence records by generating predicted distributions for more than 200,000 species worldwide, the striking loss of species' distinctiveness and biodiversity across landscapes becomes evident. The research shows that the naturalization of non-native plants was the strongest contributor to biotic homogenization, more so than extinction.

Read the research: Dura et al., 2021

Daru et al 2021. Non-native species originating (outbound arrow) or received (inbound arrows) between each continent. Line thickness is proportional to the number of species exchanged. 2
Non-native species originating (outbound arrow) or received (inbound arrows) between each continent. Line thickness is proportional to the number of species exchanged. Credit: Daru et al., 2021.

Finding Value in Undervalued Marine Products

An organization in Europe, called BlueCC, is looking into ways to utilize underutilized marine species and co-products to be used in profitable consumer products. Collagen and chiton are natural biopolymers that are often used in cosmetics, like skin creams, and dietary supplements. The collagen market is valued to be around $8.6 billion worldwide. Collagen and chiton can be extracted form invasive species and commercial fisherman by-catch, like lumpfish, starfish, and jellyfish. Chitosan is a derivative of chitin, which can be extracted from crabs and other crustaceans. Lumpfish are used as cleaner-fish in salmon aquaculture, but must be discarded when the salmon are harvested.

They hope their research will lead to the adoption of more sustainable, environmentally friendly extraction methods. Since collagen and chitin are insoluble in water, a lot of acids or alkalis is required to extract the raw material. They aim to use more environmentally friendly chemicals, and are currently looking at the use of a special strain of bacteria to be used for the extraction purpose. The organization claims to be taking a more consumer-driven approach with their research. This is done by adjusting the research based on surveys conducted to identify consumer demand and putting the consumer first. Market researchers will ask questions that will enable them to identify what the consumer wants and needs. Doing this while utilizing invasive species and undervalued marine life could allow them to turn marine residual raw materials into prototypes for new and eco-friendly products.

lumpfish. Terje Aamodt.Nofima
Lumpfish (Cyclopterus spp.). Credit: Terje Aamodt/Nofima.

Are You Eating My Crops 9 of 12

Late wilt of corn (Magnaporthiopsis maydis) is one of seven plant pathogens listed as a ‘Select Agent’ by the CDC because it has the potential to pose a serious threat to plant health. We are almost at the end of our 12-month series called ‘Are you eating my crops?’ Individual pests chosen for this series have not yet been reported in Texas, but are on the ‘Watch List’ due to their high level of pest importance or risk due to host availability. So far during this series, we have covered several different crop pests, what they look like, and where you can find more information about them. To read about previous headliners, visit the TexasInvasives.org iWire page.

Magnaporthiopsis maydis is a soil- and seed-born fungus that causes vascular wilt disease of corn just before maturity. The pathogen penetrates the root of its host and moves upward, blocking water transport and causing the host to wilt. During early stages of infection, root tips of corn are stained red, and 2-4 mm necrotic lesions appear on the roots. Aboveground plants do not generally exhibit symptoms until rapid wilting of infected plants occurs, progressing from bottom to top parts of the plant. Eventually, leaves lose color, developing a scorched appearance and the stalk becomes reddish brown. Advanced stages of infection leave the plants lower portions of the stalk dry, shrunken, and hollow. It can infect and colonize kernels, resulting in poor development, and rot of seeds and seedlings. Secondary infection by other organisms frequently can occur and progresses into stalk rot, which appears soft and wet, and is often accompanied by a sweet smell. Young plants are the most susceptible. The host typically becomes resistant to infection about 50 days after planting.

States in the southern and southeastern regions, as well as states that produce large amounts of corn, have the most suitable climate for M. maydis development and are particularly vulnerable. States with the highest risk of establishment of M. maydis are Arkansas, Illinois, Indiana, Mississippi, Missouri, Tennessee, and Texas. The most likely pathway of entry for late wilt of corn is through transport of infected Zea mays host seeds. This pathogen is known to survive in seeds for ten months or longer. Corn is the primary host. The pathogen can infect other plant species, but economic damage is only reported in corn.

Magnaportiopsi maydis may not be distinguishable from stress factors such as lack of water or nutrients or other fungal pathogens that cause stalk rot on corn in the U.S., including Fusarium graminearum, Macrophomina phaseolina, and Stenocarpella maydis. Molecular identification is required for final confirmation of this pathogen.

If you believe you have identified a Magnaportiopsi maydis infestation, please send a picture to invasives@shsu.edu.

To read more about late wilt of corn, see the USDA fact sheet.

Late wilt disease
Late wilt diseased field symptoms. Drying out ascends upwards in the plant including leaf yellowing and dehydration, and color alteration of the lower stem and internode. Credit: Degani and Cernica, 2014 .jpg

Magnaporthiopsis maydis infection on corn. Penn State Department of Plant Pathology and Environmental Microbiology
Magnaporthiopsis maydis infection on corn. Credit: Penn State Department of Plant Pathology and Environmental Microbiology.

CWMA Brazilian Peppertree Workday

Come join the Texas Gulf Region Cooperative Weed Management Area (CWMA) for an all-hands meeting and workday to help remove Brazilian peppertrees from Port Aransas, TX. The annual meeting will be held after the workshop and can be attended in person or virtually.

February 24, 2022- 9am to 12pm. Meeting place TBA in Port Aransas.

To register for the workday and/or the meeting, click here.

The CWMA is also looking for volunteers to help with outreach during the 2022 Whooping Crane Festival, February 25-27th, where they will have a booth.

For more information, email Rae Mooney.

CWMA logo

National Invasive Species Awareness Week

Participate in the largest invasive species awareness effort! National Invasive Species Awareness Week is right around the corner. This event is so full of great opportunities and advice, we are celebrating twice! Go to NISAW website for more information.

NISAW 2022 Part I: February 28 - March 4, 2022– Information and Advocacy

Watch Webinar Recordings: March 1-4, 2022

• Invasive Species Management Priorities and Opportunities for the Biden-Harris Administration and Members of the 117th Congress
• U.S. Federal Agency Updates
• Aquatic Nuisance Species Priorities for Prevention and Management
• Science, Policy, and Solutions for Invasive Species
• Show Me the Money!

NISAW 2022 Part II – Outreach and Education

Watch Webinar Recordings: May 15-22, 2022

• The Climate Crisis and Invasive Species
• Biological Threat Surveillance Tools (US Geological Survey Special Event)
• The Model Legislative Framework for State Aquatic Nuisance Species (ANS) Programs and Resource Toolkit for Local Governments
• The Regulatory Process for Classical Weed Biological Control Aquatic Plant Management Priorities
• A Comparison of State Noxious Weed Lists and The Western Weed Action Plan


North American Invasive Species Management Association Training Webinars

This program is designed to provide the education needed for professionals and students who are managing or learning to manage invasive species. The courses include the most current invasive species identification, control and management techniques, and how to comply with local and federal regulations.

Participants may register and enroll at any time, and will receive a certificate of invasive species management from NAISMA upon completion of the program.

All live webinars are open to the public. Recorded webinars are available to members of NAISMA.

NAISMA 2020 Webinar Schedule:

  • February 16, 1pm- The Power of Ethical Framing. REGISTER.
  • March 16, 1pm- Invasive reptiles and amphibians. REGISTER.
  • April 20, 1pm- A Biocultural Approach to Integrating Indigenous Knowledge with Western Science for Invasive Species Management and Policy. REGISTER.
  • May 18, 1pm- Using Community Based Social Marketing to Prevent the Spread of Invasive Species. REGISTER.


Aquatic Invasive Species Management 101

This online class is perfect for anyone who wants to be better informed about aquatic invasive species (AIS) management strategies. You will gain an introduction to AIS control and aquatic plant management, a better understanding of pesticides, how they work, and the regulations around their use, insight on non-chemical treatment options, a better ability to evaluate and understand management effectiveness, and take a longer-term view of management.

This course is offered by the AIS Detectors program at the University of Minnesota which is jointly supported by the Minnesota Aquatic Invasive Species Research Center and University of Minnesota Extension. It is open to anyone, including residents of other states, though certain portions of the course, such as permitting regulations, will include information specific to Minnesota.

Click here for more information or registration. Scholarships are available for discounted course fee. Registration is open now.

AIS Management 101jpg  

Invasive Spotlight:

Japanese Climbing Fern
(Lygodium japonicum)

Japanese climbing fern (Lygodium japonicum) is a perennial viney fern, climbing to 90 feet (30 m) long, with lacy, finely divided leaves along green to orange to black wiry vines. It can form mats of shrub- and tree-covering infestations. Tan-brown fronds persist in winter, while others remain green if warm enough. Its vines arise from underground creeping rhizomes that are slender, black, and wiry.

Japanese climbing fern is an ornamental climbing fern that is native to Asia and tropical Australia and was introduced from Japan in the 1930s. It is now rapidly spreading across the forested areas of Eastern Texas, smothering native trees and shrubs. Not only does it impact native vegetation directly, but it is also a significant fire hazard: the dead fern fronds serve as a fire ladder to carry fire to the crown of trees. It occurs in at least 25 East Texas counties.

As a fern, this invasive plant reproduces via spores. The spores can be carried miles by the wind, easily spreading the fern. It occurs along highway rights-of-way, and invades open forests, forest road edges, and stream and swamp margins.

Because of its negative impacts, Japanese climbing fern is a part of the Sentinel Pest Network, a component of Texasinvasives.org. Please Report It! here, particularly if you are in counties not highlighted on this distribution map.

For more information regarding management and removal of the Japanese climbing fern, see the TexasInvasives info page here.

Japanese climbing fern (<em>Lygodium japonicum</em>) intwined around vegetation. Credit: Chuck Bargeron, University of Georgia.
Japanese climbing fern (Lygodium japonicum) intwined around vegetation. Credit: Chuck Bargeron, University of Georgia.

 Japanese climbing fern. Karan A. Rawlins. University of Georgia 
Leaf of Japanese climbing fern. Credit: Karan A. Rawlins, University of Georgia

Opportunities To Get Involved
Looking for participants for the following surveys: 

Citrus Greening Workshops

We need your help to safeguard Texas Citrus, and it can start in your backyard!

TISI is offering educational workshops focused on the Asian citrus psyllid and the pathogen Citrus Greening. The Asian citrus psyllid and the Citrus Greening pathogen is threatening citrus in multiple Texas counties, and we need your help to monitor the spread. The workshop will highlight what you need to look out for, address USDA-APHIS Citrus Quarantines, and offer diagnostic services if you suspect your backyard citrus has either the psyllid pest or Citrus Greening pathogen. This includes providing trapping materials, assisting with management strategies, and more.

Please contact invasives@shsu.edu so we can schedule a workshop (virtual or in-person) for you or your group this year!

Aquarium Watch: Looking for Prohibited Invasive Aquatic Species

Please help texasinvasives.org and natural habitats by looking for 14 prohibited invasive aquatic species being sold in your local aquarium store. With just one photo you can assist us in finding and documenting which stores are selling prohibited species. Texasinvasives.org will contact the appropriate Texas institutions to remove the species for sale.

If you would like more information please email invasives@shsu.edu, and mention you want to assist with our Aquarium Watch.

Air Potato Survey

Help Texas Research Institute for Environmental Studies conduct an air potato survey by actively reporting any infestations seen in your area. The air potato (Dioscorea bulbifera) is a fast growing, high climbing vine. Potato-like tubers are the primary means of reproduction for this vine. They can be as small as a marble or as large as a softball. Native yams are often confused for air potatoes, to avoid this confusion please refer to the key below:

- Plants rhizomatous; bulbils never produced in leaf axils; petiole base never clasping the stem; Native D. villosa
- Plants tuberous; bulbils produced in leaf axils; petiole base sometimes clasping the stem; Invasive D. bulbifera

For additional information, please refer to the TexasInvasives information page.

If you believe you have identified an air potato vine, please email invasives@shsu.edu and include the following information: an image, an approximate number of vines present, the location (including whether it is on public or private land), and if bulbils are present (the potato-like tubers that emerge from the stem).

Citrus greening. JM Bove

Leaf mottle on grapefruit, a characteristic symptom caused by citrus greening bacterium but also seen on trees infected by Spiroplasma citri. Credit: J.M. Bove.

Armorded catfish. Photographer United States Geological Survey
Armored catfish (Hypostomus plecostomus). Credit: United States Geological Survey.

air-potato (Dioscorea bulbifera)2 bulbil. credit Karen Brown
Air-potato (Dioscorea bulbifera), bulbil emerging from leaf axil. Credit: Karen Brown.

More News

Austin Restaurateur Wants Texans to Save the Environment - by Eating Wild Hogs
In Austin’s Cherrywood neighborhood, the Dai Due restaurant has an unusual menu item- a wild boar confit created with locally sourced ingredients. texasstandard.org

More Than 400 Invasive Fish Dumped from Aquariums Found in Texas River
Hundreds of suckermouth armored catfish, also known as "plecos," were removed from San Marcos River in Texas over the past few weeks. the two universities associated with the fish removal are working on research as it relates to the suckermouth armored catfish and its population. newsweek.com

Study Shows the Impact of Preemergent Herbicides on Native Plants
Though invasive weeds can devastate native plant communities, a recent study shows that efforts to manage those weeds can cause harm when using a non-target herbicide like indaziflam. phys.org

Climate Change, Invasive Species Drive Native Trout Declines
Researchers have found that climate change drives native trout declines by reducing stream habitat and facilitating the expansion of invasive trout species. sciencedaily.com

New Bioinformatics Tool Spots Hybrid Fish That Threaten the Survival of Natural Tilapia Populations
A new genomics marker tool has been shown to accurately identify tilapia species and tell apart invasives, hybrids and native species, providing a novel resource to help developing aquaculture. phys.org

Suspicious-Looking Snails Spur 'Sinking Feeling'
Examination of invasive New Zealand mudsnails (Potamopyrgus antipodarum) in Michigan waterbodies. These snails are the size of a grain of rice and can pass through the digestive tract of a trout alive. record-eagle.com

9 of the Worst Invasive Species in the U.S.
A list of some of the most notorious invasive species that have infiltrated the U.S. or gained a toehold where they don’t belong thanks to human influence. gizmodo.com

UK Red Squirrel Conservation Strategies Likely to Undermine Species Survival In Future
New research has shown how current red squirrel (Sciurus vulgaris) conservation strategies in the UK and Ireland, that favor non-native conifer plantations, are likely to negatively impact red squirrels. phys.org

University of Canberra to Lead Nation on Edna Technology
The University of Canberra, Australia, will set the national standard on a technique for discovering pests in imported goods. canberratimes.com

Long-Sought Great Lakes Projects Get Funding Under New Law
Projects that will boost Great Lakes shipping in a crucial bottleneck and those intended to protect the lakes from invasive carp will get big funding increases. phys.org


If you would like to highlight a successful invasive species project or nominate a special person to be highlighted in an upcoming iWire, please send the details to iwire@texasinvasives.org.

Sentinel Pest Network and Invaders of Texas Workshops

Invaders of Texas workshops train volunteers to detect and report invasive species as citizen scientists. Workshops, which are free, are designed to introduce participants to invasive species and the problems they cause, cover aspects of invasive species management, teach identification of local invasive plants, and train participants to report invasive plants using the TX Invaders mobile application. The workshop is 7 hours long (usually on a Saturday, but scheduling is arranged with each individual host group). The workshop satisfies Master Naturalist training requirements.

Sentinel Pest Network workshops serve to increase the awareness and early detection of a set of particularly important invasive species to help prevent their spread into Texas or their further spread within Texas. Participants learn to identify species such as the Emerald Ash Borer, Cactus Moth, Asian Longhorned Beetle, and other pests of regulatory significance, and to report them. The workshop is 3.5 hours long. The workshop satisfies Master Naturalist training requirements.

Upcoming Workshops:

Invaders of Texas Citizen Science Training Workshop Date: February 19th, 2021
Time: 8:30-12:30
Place: In-person, The Woodlands Fire Dept Training Center, 16135 IH-45 South, Conroe 77385
Open to the public.
Please register here.

For more information or to register to attend a free workshop, please visit the Workshop Page.