It’s October and That Means it’s Time for Halloweed

It’s October and That Means it’s Time for Halloweed

What is Halloweed?

It’s a national program where volunteers gather at a public space to help remove invasive weeds.  In many cases they target one specific species.  This year in Escambia County we plan to target beach vitex on Pensacola Beach.  If there is not an event in your community, you can still participate by removing invasive weeds from your own private property.  Here is how…

  1. Target one specific species.  Maybe Chinese tallow, Japanese climbing fern, or other possible invasive weeds in your community.  If you are not sure which weeds are invasive, check with your local county extension office. 
  2. Read how to best manage.  Each species may use different methods and herbicides to treat.  Maybe you do not want to use herbicides, not a problem, by visiting the website of the University of Florida’s Center for Aquatic and Invasive Plants, you can find fact sheets that will give you not only the different herbicides that can be effective, but other non-herbicide management ideas. 
  3. Decide what you are going to do with the weeds afterwards.  Fragments and seeds from these weeds can generate new populations.  You make sure you dispose of the plant properly to not create a bigger problem. 
  4. Pick a nice day, collect all your supplies, and do it. 
  5. Let us know!  Contact me (Rick O’Connor and let us know which species you removed and how much.

If you are in Escambia County and want to participate in our event this year, we will be removing beach vitex from public areas on Pensacola Beach.  You will need gloves, loppers or clippers, and a 5-gallon bucket.  Here is our schedule…

Oct 4     12:00pm             Quietwater Boardwalk.  Meet at the seashell. 

Oct 12   12:00pm             The Bike Path near the Sugar Bowl.  Meet at parking lot 27A (Allen Levin Way).  

Oct 18   12:00pm             The sewer lift station on Via DeLuna just west of the west entrance into

Sugar Bowl.

Oct 25   12:00pm             Bike Path near Portofino.  Meet at parking lot 27B. 

If you plan to come to one of these, let me know!   Rick O’Connor at

Vitex beginning to take over bike path on Pensacola Beach. Photo credit: Rick O’Connor
Meet the New Invasive Species on the Barrier Islands; Cogongrass

Meet the New Invasive Species on the Barrier Islands; Cogongrass

Miami is ground zero for invasive species in this state.  But the Florida panhandle is no stranger to them.  Where they are dealing with Burmese pythons, melaleuca, and who knows how many different species of lizards – we deal with Chinese tallow, Japanese climbing fern, and lionfish.  The state spends hundreds of thousands of dollars each year battling and managing these non-native problem species.  By definition, invasive species cause environmental and/or economic problems, and those problems will only get worse if we do not spend the money to manage them.  Those who work in invasive science and resource management know that the most effective way to manage these species is to detect them early and respond rapidly. 

The Invasive Species Curve

Invasive species have made their way to the coastal waters and dunes of the barrier islands in the Florida panhandle.  Beach vitex, Brown anoles, and Chinese tallow are found on most.  Recently on Perdido Key near Pensacola, we found a new one – cogongrass. 

Cogongrass (Imperata cylindrica) was accidentally introduced to the Gulf coast via crates of satsumas entering the port of Mobile in 1912.  It began to spread from there and has covered much of the upland areas of the southeastern U.S.  It has created large problems within pasture lands, where livestock will not graze on it, and in pine forest where it has decreased plant and animal biodiversity as well as made prescribed burning a problem – it burns hot, hot enough to actually kill the trees.  The impacts and management of this plant in that part of the panhandle has been known for a long time.  The Department of Agriculture lists it as one of the most invasive and noxious weeds in the country. 

Cogongrass seedheads are easily spotted in spring. Photo credit: Mark Mauldin

Two years ago cogongrass was discovered growing around a swimming pool area at a condo on Perdido Key.  To be considered an invasive species you must (a) be non-native to the area – cogongrass is certainly non-native to our barrier islands, (b) have been introduced by humans (accidentally or intentionally) – strike two, we THINK it was introduced by mowers.  This is a common method of spreading cogongrass, mowing an area where it exists, then moving those mowers to new locations without cleaning the equipment.  We do not know this is how it got to the island, but the probability is high.  Third, it has to be causing an environmental and/or economic problem.  It certainly is north of the I-10, but it is not known what issue it may cause on our barrier islands.  Could it negatively impact protected beach mice and nesting sea turtle habitat?  Could alter the integrity of dunes to reduce their ability to hold sand and protect properties.  Could it overtake dune plants lowering both plant and animal diversity thus altering the ecology of the barrier island itself?  We do not know.  What we do know is that if we want to eradicate it, we need to detect it early and respond rapidly. 

According to – there are 75 records of cogongrass on the barrier islands, and coastal beaches of the Florida panhandle.  This is most likely under reported.  So, step one would be to conduct surveys along your islands and beaches.  Florida Sea Grant and Escambia County of Marine Resources are doing just that.  EDDMaps reports five records on Perdido Key and four at Ft. Pickens.  It most likely there is more.  A survey of the northeast area of Pensacola Beach (from Casino Beach east and north of Via De Luna Drive) has found two verified records and two unverified (they are on private property, and we cannot approach to verify).  Surveys of both islands continue. 

The best time to remove/treat cogongrass is in the fall.  The key to controlling this plant is destroying the extensive rhizome system.  In the upland regions, simple disking has been shown to be effective if you dig during the dry season, when the rhizomes can dry out, and if you disk deep enough to get all of the rhizomes.  Though the rhizomes can be found as deep as four feet, most are within six inches and at least a six-inch disking is recommended.  Depending on the property, this may not be an option on our barrier islands.  But if you have a small patch in your yard, you might be able to dig much of it up. 

Chemical treatments have had some success.  Prometon (Pramitol), tebuthurion (Spike), and imazapyr have all had some success along roadsides and in ditches north of I-10.  However, the strength of these chemicals will impede new growth, or plantings of new plants, for up to six months.  There are plants that are protected on our islands and on Perdido Key any altering of beach mouse habitat is illegal.  We certainly do not want to kill plants that are holding our dunes.  If you feel chemical treatment may be needed for your property, contact the county extension office for advice. 

Most recommend a mixture of burning, disking, and chemical treatment.  But again, this is not realistic for barrier islands.  Any mechanical removal should be conducted in the summer to remove thatch and all older and dead cogongrass.  As new shoots emerge in late summer and early fall herbicides can then be used to kill the young plants.  Studies and practice have found complete eradication is difficult.  It is also recommended not to attempt any management while in seed (in spring).  Tractors, mowers, etc. can collect the seeds and, when the mowers are moved to new locations, spread the problem.  If all mowing/disking equipment can be cleaned after treatment – this is highly recommended. 

Step one would be to determine if you have cogongrass on your property, then seek advice on how to best manage it.  For more information on this species, contact your local extension office. 

New Gulf of Mexico Sea Grant Science Outreach Publications

New Gulf of Mexico Sea Grant Science Outreach Publications

The Gulf of Mexico Sea Grant Science Outreach Team is proud to announce four new outreach items that are applicable throughout the US and showcases marine microplastics and homeowners’ insurance:

How Hot Can You Go?  Warmer bay waters and the thermal maximums of estuarine creatures

How Hot Can You Go?  Warmer bay waters and the thermal maximums of estuarine creatures

I attended a meeting recently where one of the participants stated – “We have been looking at a lot of water quality parameters within our bay in recent years, and plan to look at more, but has anyone been looking at temperature?”

What he was referring to was that the focus of most monitoring projects has been nutrients, dissolved oxygen, etc.  But most agencies and universities who have been conducting long term monitoring in our bays are collecting temperature data as well.  His question was not whether they have or not but has anyone looked at this long-term temperature data to see trends. 

I know from some of the citizen science monitoring I have been involved with that temperature is collected but (anecdotally) does not vary much.  It is like pH, we collect it, it is there, but does change drastically (anecdotally) over time.  However, it has been a very hot year.  This “heat dome” that has been sitting over the Midwest and southeast this summer has set records all across the region.  Someone monitoring water temperature in East Bay recently reported surface water temperature at 96°F (36°C).  Many have stated that swimming in our waters at the moment feels like swimming in bath water.   It’s not just warm in your yard, it is warm in the bay.  And this brings up the question of thermal tolerance of estuarine species.

All creatures have a temperature tolerance range.  They resemble a bell curve where you have the thermal minimum at one end, the thermal maximum at the other, and the “preferred” temperatures near the top of the bell curve (see image below).  Many creatures have a large tolerance for temperature shifts (their bell curves extend over a larger temperature range).  You find such creatures in the temperate latitudes where temperature differences between summer and winter are larger.  Others have a lower tolerance, such as those who are restricted to polar or tropical latitudes.  Within an estuary you can find creatures with varying thermal tolerances.  Some have a larger tolerance than others.  Ectothermic (cold-blooded) creatures often have a wider range of temperatures they can survive at than endothermic (warm-blooded) ones.  Homotherms (creatures who maintain their body temperature near a fixed point – such as humans 98.6°F/37°C) expend a lot of energy to do this.  When environmental temperatures rise and fall, they have to expend more to maintain it at their fixed temperatures. 

Image provide by Research Gate.

It is also true that most creatures prefer to exist near their thermal maximum.  In other words, the bell curve is sort of skewed towards the warmer end of their range.  But what is their thermal maximum?  What happens when they reach it?  How hot can they go?

Local waters are warmer this year. Photo: Rick O’Connor

The studies I reviewed suggested that the thermal maximum is dependent on other environmental factors such as salinity and dissolved oxygen.  In most cases, the higher the salinity, the higher the thermal maximum was.  I looked at studies for the eastern oyster (Crassostrea virgincia), the brown shrimp (Farfantepenaeus aztectus), the blue crab (Callinectes sapidus), the Spot Croaker (Leiostomus xanthurus), and the pinfish (Lagodon rhomboides).  The oyster, shrimp, and blue crab support important commercial fishery.  The spot croaker is a dominant fish species in the upper estuary where the pinfish is a dominant species in the lower sections.  These studies all suggested that again, depending on salinity, dissolved oxygen, pressure, and rate of temperature increase, the thermal maximum could happen as low as 30°C (86°F) and as high as 40°C (104°F), with many having a thermal maximum between 35-40°C. 

At these temperatures proteins begin to denature and biological systems begin to shut down.  Most of the studies determined the endpoint at “loss of equilibrium” and not actually death.    Our estuaries can certainly reach these temperatures in the summer.  Again, one recent reading in East Bay (within the Pensacola Bay system) was 96°F (36°C). 

So, what do these creatures do when such temperatures are reached?

The most obvious response is to move, find cooler water.  These are often found in deeper portions of the bay below the thermocline (a point in the water column where water temperatures significantly change – usually decreasing with depth).  However, many sections of our estuaries are shallow and deep water cannot be found.  In these cases, they may move great distances to seek deeper water areas, or even move to the Gulf of Mexico.  In some cases – like with oysters – they cannot move, and large die-offs can occur.  Other responses include lower metabolic rates and decline in reproduction. 

We know that throughout history, there have been warmer summers than others and heat waves have happened.  In each case, depending on other environmental factors, estuarine creatures have adapted, and some members have survived, to keep their populations going. 

We know that large scale die-offs have occurred in the past and the tougher species have continued on. 

We also know that the planet is warming, and it would be interesting to look at how the water temperatures have changed over the last few decades.  Are they increasing?  Are they reaching the thermal maximums of the creatures within our bay?  How will these creatures respond to this? 

How hot can they go?

Meet the Barnacle

Meet the Barnacle

You might say this is a strange title – “meet the barnacle” – because everyone knows what a barnacle is… or do they? 

As a marine science instructor, I gave my students what is called a lab practical.  This is a test where you move around the room and answer questions about different creatures preserved in jars.  Almost every time that got to the barnacle they were stumped.  I mean they knew it was a barnacle but what kind of animal is it?  What phylum is it in? 

Going through a thought process they would more often than not choose that it was a mollusk.  This makes perfect sense because of the calcium carbonate shell it produces.  As a matter of fact, science thought it was a mollusk until 1830 when the larval stage was discovered, and they knew they were dealing with something different.  It is not a mollusk.  So… what IS it?  Let’s meet the barnacle…

Barnacles along the seashore is a common site for many. Photo: NOAA

The barnacle is actually an arthropod.  Yep… the same group as crabs and shrimp, insects and spiders.  Weird right…

But that is because the creature down within that calcium carbonate shell is more like a tiny shrimp than an oyster.   It is in the class Cirripedia within the subphylum Crustacea.  It is the only animal in this class and the only sessile (non-motile) crustacean. 

Barnacles are exclusively marine.  This has been helpful when conducting surveys for terrapins or assessing locations for living shorelines – if you see barnacles growing on rocks, shells, or pilings, it is salty enough.  There are over 900 species described and they live independently from each other attached to seawalls, rocks, pilings, boats, even turtle shells.  Louis Agassiz described the barnacle as “nothing more than a little shrimplike creature, standing on its head in a limestone house kicking food into its mouth.” 

This image from a textbook shows the internal structure of a barnacle. Notice the shrimplike animal on its back with extendable appendages (cirri) for feeding. Image: Robert Barnes Invertebrate Zoology.

The planktonic barnacle larva settles to the bottom and attaches to a hard substrate using a cement produced from a gland near the base of their first set of antenna (crustaceans, unlike insects and spiders, have two sets of antenna).  It is usually head down/tail up and begins to secrete limestone plates forming the well known “shell” of the animal.  Some barnacles produce a long stalk near the head end (called the peduncle) which holds the adhesive gland and it is the peduncle that attaches to the hard substrate, not the head directly.  The goose neck barnacle is an example of this.  We find them most often in the wrack along the Gulf side of our beaches attached to driftwood or marine debris. 

Lucky was found in the Gulf of Mexico. He had been there long enough for these goose neck barnacles to attach and grow. Photo: Bob Blais

The “shell” of the barnacle is a series of calcium carbonate plates they secrete.  These plates overlap and are connected by either a membrane or interlocking “teeth”.  The body lies 90° from the point of attachment on its back. 

There are six pairs of “legs” which are very long and are extended out of the “doors” of the shell and make a sweeping motion to collect planktonic food in the water column.  They are most abundant in the intertidal areas were there are rocks, seawalls, or pilings. 

Most species are hermaphroditic (possessing both sperm and egg) but cross fertilization is generally the rule.  Barnacles signal whether they are acting males or females via pheromones and fertilization occurs internally, the gametes are not discharged into the water column as in some mollusks and corals.  The developing eggs brood internally as well.  Our local barnacle (Balanus) breeds in the fall and the larva (nauplius) are released into the water column in the spring by the tens of thousands.  The larva goes through a series of metamorphic changes until it settles on a hard substrate and becomes the adult we know.  They usually settle in dense groups in order to enhance internal fertilization for the next generation.  Those who survive the early stages of life will live between two and six years. 

So, there you go… this is what a barnacle is… a shrimplike crustacean who is attached to the bottom by its head, secretes a fortress of calcium carbonate plates around itself, and feeds on plankton with its long extending legs.  A pretty cool creature. 


Barnes, R.D. 1980. Invertebrate Zoology. Saunders College Publishing.  Philadelphia PA.  pp. 1089.