The Dolphin Tour

The Dolphin Tour

I recent took my granddaughter on a dolphin tour out of Pensacola Beach.  It was amazing.  It was a cool October morning, not a cloud in the sky, the winds were calm, the water crystal clear due to the lack of rain over the past few weeks, and the dolphins were out. 

They are amazing animals and always seem to grab your attention no matter how many times you see them.  I was a student at Dauphin Island Sea Lab from 1980-81 and taught there from 1985-1990.  No matter how many times we heard “dolphins” when out on one of the research vessels, everyone had to run over to look.  People do enjoy seeing dolphins.  There is just something about them. 

A group of small dolphin leap from the ocean. Photo: NOAA

During the tour at one location, we saw a group of them (a pod) feeding on fish in the shallow water.  They would roll and chase, you could see the sand being kicked up from the bottom as they did.  At another location we saw them in breeding mode.  Slower moving, caressing, fluke slapping as they turned all around in the water near us.  The tour guide told us all sorts of dolphin facts, and some great jokes to go along with them.  It was a good program, and my granddaughter was loving it. 

She looked over at me at one point and said, “dolphins use to walk on land”.  I responded that actually their ancestors did.  Dolphins, as we know them, were very much aquatic animals.  This led to thoughts on other dolphin questions I have heard over the years.

What is the difference between a dolphin and a whale?

Size… and in some cases teeth. 

All whales and dolphins are in the mammalian order Cetacea.  Mammalian orders are divided based on the type of teeth they have.  Cetaceans are homodonts, meaning they have only one type of tooth.  For the toothed whales, these are canines, they lack the molars and incisors that many other mammals have.  But some have no teeth rather a specialized fibrous material called baleen, similar to the bristles of a broom, with which they can filter plankton from the water. 

There are over 90 species of cetaceans in the world’s oceans, 21 of those are known from the Gulf of Mexico.  In a recent published survey by the National Marine Fisheries Service, most of the cetaceans in the Gulf of Mexico are of the toothed whale variety and most occur beyond the continental shelf (which is between 60 and 140 miles south of Pensacola).  The only baleen whale in their report was the Byrde’s Whale (Balanopatera edeni).  They estimate about 33 of these whales based on their transect surveys and all of these were found beyond the continental shelf between Pensacola and Apalachicola Florida.  The largest of the toothed whales reported was the sperm whale, which can reach over 60 feet.  They estimate 763 sperm whale in the Gulf, and they were found across the basin beyond the continental shelf. 

But it is the bottlenose dolphin (Tursiops truncatus) that we see on the dolphin tours.  This is a relatively small toothed whale, reaching lengths of 13 feet, though most in the Gulf region are less than 10 feet.  They are the most abundant and most frequently encountered cetacean near shore and within the estuaries and seem to prefer these shallower waters to the open Gulf beyond the shelf.  The National Marine Fisheries Service divides them into stocks based on their geographic distribution.  They report 37 different stocks of bottlenose dolphins in the northern Gulf.  These are divided into western, eastern, and northern stocks, and then subdivided into estuarine stocks.  There are separate stocks for the Perdido Bay and Pensacola Bay groups.  This report indicated the stock size for the Pensacola and Perdido Bay dolphins was unknown, though our tour guide indicated there were about 250 in the Pensacola Bay stock.  The National Marine Fisheries Service did report about 179 dolphins in the Choctawhatchee Bay stock.  The reports estimated over 51,000 individuals for the northern Gulf. 

Though not listed as endangered or threatened by the Endangered Species Act, there is some concern on the smaller estuarine stocks and so they have been labeled as “strategic”.  There has been fishery related mortality with these dolphins in our waters, primarily with longlining and otter trawl operations, but losses are less than four animals/year and do not seem to be impacting their populations. 

What is the difference between a dolphin and a porpoise?

Though many associate the long beak as a dolphin, there are dolphins with short snouts.  Killer whales are actually large dolphins.  The answer goes back to the teeth, as it always does when classifying mammals.  Dolphins have conical shaped teeth where porpoise have more spade shaped ones. 

How smart are dolphins?

As everyone knows these are highly intelligent animals.  They use an audible form of communication that includes squeaks, clicks, and whistles, to keep the pod together.  Researchers have discovered that these audible sounds have a sort of “accent” to them that tells dolphins which pod the dolphin communicating is from.  This appears to be very important being that dolphins from one social pod may not accept others from different one.  I remember in 1993 when a group of five pantropical spotted dolphins stranded on Pensacola Beach.  There were four adults and one 3-month year old in the group.  After failed attempts to return the dolphins back to the Gulf, it was decided to transport them to a quarantine area near the EPA lab on Pensacola Beach. There was a virus spreading through some European populations and they did not want to risk taking them to the Gulfarium.  In route three of the four adults passed away.  The remaining adult was named Mango and the juvenile was named Kiwi.  After a period of time in quarantine Mango passed away leaving on the young Kiwi.  There was a move to return Kiwi to the wild but some of the dolphin experts on scene told me the likely hood of a different pod accepting Kiwi was a risk, and finding her original pod was very unlikely.  After determining the dolphin did not have the virus of concern, they decided to move her to the Gulfarium in Ft. Walton Beach, where she lived the rest of her life. 

How does dolphin echolocation work?

Echolocation is different than communication, in that it is inaudible.  As with communication, the sounds are produced by expelling air through the blowhole.  In the case of communication, there is a muscle that partially closes the opening of the blowhole producing the sounds we hear.  In echolocation this is completely closed, and the sound waves are moved through a fat filled melon near the head.  The shape and density of the melon can be changed by the animal to produce different frequencies of sound but all inaudible to our ears.  These sounds are emitted through the melon into the environment, where they contact something and “echo” back to the dolphin.  These echoes are received in a fat filled cavity of the lower jaw and transferred to the brain – where the animal is then made aware of the object out in front of them.  Some studies suggest that it may be more than knowing there is an object, they may be able to distinguish different kinds of fish.  Though it is most effective within 600 feet, studies show their range may be up to 2000 feet.  Studies have also shown that some species of toothed whales can alter the frequency of these echolocated sounds to stun their prey making them easier to catch. 

Dolphins are amazing animals. 

They live between 30 and 50 years in the wild.  During this time, they form tight social groups, feed on a variety of prey, and produce new members every 2-3 years.  There is so much more to the biology, ecology, and social life of these animals and we recommend you read more.  Once you understand them better, we also recommend you take a dolphin tour to view these amazing creatures. 

October is Coastal Dune Lake Appreciation Month

October is Coastal Dune Lake Appreciation Month

October has been designated as Coastal Dune Lake Appreciation month by Walton County government. Walton County is home to 15 named coastal dune lakes along 26 miles of coastline. These lakes are a unique geographical feature and are only found in a few places in the world including Madagascar, Australia, New Zealand, Oregon, and here in Walton County.

A coastal dune lake is defined as a shallow, irregularly shaped or elliptic depressions occurring in coastal communities that share an intermittent connection with the Gulf of Mexico through which freshwater and saltwater is exchanged.  They are generally permanent water bodies, although water levels may fluctuate substantially.  Typically identified as lentic water bodies without significant surface inflows or outflows, the water in a dune lake is largely derived from lateral ground water seepage through the surrounding well-drained coastal sands.  Storms occasionally provide large inputs of salt water and salinities vary dramatically over the long term.  

Our coastal dune lakes are even more unique because they share an intermittent connection with the Gulf of Mexico, referred to as an “outfall”, which aides in natural flood control allowing the lake water to pour into the Gulf as needed. The lake water is fed by streams, groundwater seepage, rain, and storm surge. Each individual lake’s outfall and chemistry is different. Water conditions between lakes can vary greatly, from completely fresh to significantly saline.

A variety of different plant and animal species can be found among the lakes.   Both freshwater and saltwater species can exist in this unique habitat.  Some of the plant species include: rushes (Juncus spp.), sedges (Cyperus spp.), marshpennywort (Hydrocotyle umbellata), cattails (Typha spp.), sawgrass (Cladium jamaicense), waterlilies (Nymphaea spp.), watershield (Brasenia schreberi), royal fern (Osmunda regalis var. spectabilis), rosy camphorweed (Pluchea spp.), marshelder (Iva frutescens), groundsel tree (Baccharis halimifolia), and black willow (Salix nigra).

Some of the animal species that can be found include: western mosquitofish (Gambusia affinis), sailfin molly (Poecilia latipinna), American alligator (Alligator mississippiensis), eastern mud turtle (Kinosternon subrubrum), saltmarsh snake (Nerodia clarkii ssp.), little blue heron (Egretta caerulea), American coot (Fulica americana), and North American river otter (Lutra canadensis). Many marine species co-exist with freshwater species due to the change in salinity within the column of water.

The University of Florida/IFAS Extension faculty are reintroducing their acclaimed “Panhandle Outdoors LIVE!” series. Come celebrate Coastal Dune Lake Appreciation month as our team provides a guided walking tour of the nature trail surrounding Western Lake in Grayton Beach State Park. Join local County Extension Agents to learn more about our globally rare coastal dune lakes, their history, surrounding ecosystems, and local protections.  Walk the nature trail through coastal habitats including maritime hammocks, coastal scrub, salt marsh wetlands, and coastal forest.  A tour is available October 19th.

The tour is $10.00 (plus tax) and you can register on Eventbrite (see link below). Admission into the park is an additional $5.00 per vehicle, so carpooling is encouraged.  We will meet at the beach pavilion (restroom facilities available) at 8:45 am with a lecture and tour start time of 9:00 am sharp.  The nature trail is approximately one mile long, through some sandy dunes (can be challenging to walk in), on hard-packed trails, and sometimes soggy forests.  Wear appropriate footwear and bring water.  Hat, sunscreen, camera, binoculars are optional. Tour is approximately 2 hours. Tour may be cancelled in the event of bad weather.

Register here on Eventbrite: https://www.eventbrite.com/e/panhandle-outdoor-live-coastal-dune-lake-lecture-and-nature-trail-tour-tickets-419061633627

Bluefish of the Florida Panhandle

Bluefish of the Florida Panhandle

“Bluefish!” … “It’s just a school of bluefish!”  So yelled the lifeguard in Jaws II when Chief Brody had mistaken a school of bluefish for the rogue great white shark that was plaguing the town.  He would not have been the first to mistake these large schools for a larger fish, particularly a predatory shark, but as some know, bluefish are quite predatory themselves.

Bluefish
Image: University of South Florida

Growing up along the Florida panhandle we heard little about this species.  We had heard stories of large bluefish schooling along the Atlantic coast killing prey with their razor-sharp teeth and, at times, biting humans.  But not much was mentioned about them swimming along our shores.  But they do, and I have caught some.

Bluefish are one of several in a group Hoese and Moore refer to as “mackerel-like fish” in Fishes of the Gulf of Mexico. They differ in that they lack the finlets found along the dorsal and ventral sides of the mackerel body and mackerels lack scales having a smoother skin.  Bluefish are the only members of the family Pomatomidae.  They can reach three feet in length and up to 30 pounds.  They travel in large schools viciously feeding on just about anything they can catch and seem to really like menhaden.  They move inshore for feeding and protection from larger ocean predators but do move offshore for breeding.

Bluefish landed from the Gulf of Mexico are much smaller than their Atlantic cousins, rarely weighing in more than three pounds.  They do have a deep blue-green color to them and thin caudal peduncle and forked tail giving them the resemblance of a mackerel or jack.  Some say they are bit too oily to eat while others enjoy them quite a bit.  There is a commercial fishery for them in Florida and, as you would expect, it is a larger fishery along the east coast.  Most of the panhandle counties have had commercial landings, albeit small ones.

Biogeographically, the blue fish are found all along the Atlantic seaboard and into the Gulf of Mexico.  It is listed as worldwide but seems to be absent from the Caribbean and other tropical seas.  This could be due to a distaste of warmer waters, or the lack of their prey targets.

They are an interesting and less known fish in our region.  Swimming in a school of them should be done with caution, there are reports of nips and bites from these voracious predators.

Sea Bass and Grouper of the Florida Panhandle

Sea Bass and Grouper of the Florida Panhandle

When you look over the species of sea basses and groupers from the Gulf of Mexico it is a very confusing group.  Hoese and Moore1 mention the connections to other families and how several species have gone through multiple taxonomic name changes over the years – its just a confusing group.

Gag grouper.
Photo: National Oceanic and Atmospheric Administration

But when you say “grouper” everyone knows what you are talking about, and everyone wants a grouper sandwich.  This became a problem because what people were serving as “grouper” may not have been “grouper”.  And as we just mentioned what is a grouper anyway?  The families and genera have changed frequently.  Well, this will probably get more technical than we want, but to sort it out – at least using the method Hoese and Moore did in 1977 – we will have to get a bit technical.

 

“Groupers” are in the family Serranidae.  This family includes 34 species of “sea bass” type fish.  Serranids differ from snappers in that they lack teeth on the vomer (roof of their mouths) and they differ from “temperate basses” (Family Percichthyidae) in that their dorsal fin is continuous, not separated into two fins.  These are two fish that groupers have been confused with.

Banked Sea Bass.
Photo: National Oceanic and Atmospheric Administration.

We can subdivide the serranids into two additional groups.  The “sea basses” have fewer than 10 spines in their dorsal fin.  There are 10 genera and 18 species of them.  They have common names like “bass”, “flags”, “barbiers”, “hamlets”, “perch”, and “tattlers”.  They are small and range in size from 2 – 18 inches in length.  Most are bottom reef fish with little commercial value for fishermen.  Most are restricted to the tropical parts of the Atlantic basin but two are only found in the northwestern Gulf, one is only found in the eastern Gulf, and one has been found in both the Atlantic and Pacific.  The biogeography of this group is very interesting.  The same species found in both the Atlantic and Pacific suggest an ancient origin.  The variety of serranid sea bass suggest a lot of isolation between groups and a lot of speciation.

 

The ”groupers” have 10 or more spines in their dorsal fin.  There are two genera in this group.  Those in the genus Epinephelus have 8-10 spines in their anal fin and have some canine teeth.  Those in the genus Mycteroperca have 10-12 spines in their anal fin and lack canine teeth.  Within these two genera there are 15 species of grouper, though the common names of “hind”, “gag”, “scamp” are also used.  Most of these are found along the eastern United States and Gulf of Mexico.  Five species are only found in the tropical parts of the south Atlantic region, five are also found across the Atlantic along the coast of Africa and Europe, and – like the “sea bass” two have been found in both the Atlantic and the Pacific.  They range in size from six inches to seven feet in length.  The Goliath Grouper can obtain weights of 700 pounds!  Like the sea bass, groupers prefer structure and can live a great depths.  Unlike sea bass they are heavily sought by commercial and recreational anglers and are one of the more economically important groups of fish in the Gulf of Mexico.

The massive size of a goliath grouper. Photo: Bryan Fluech Florida Sea Grant

One interesting note on this family of fish is that most are hermaphroditic.  The means they have both ovaries (to produce eggs) and testes (to produce sperm).  Sequential hermaphrodism is when a species is born one sex but becomes the other later in life.  This is the case with most groupers, who are born female and become male later in life.  However, the belted sand bass (Serranus subligarius) is a true hermaphrodite being able to produce sperm and egg at the same time – even being able to self-fertilize.

 

For many along the Florida panhandle, their biogeographic distribution and sex do not matter.  It is a great tasting fish and very popular with anglers.  For those with a little more interest in natural history of fish in our area, the biology and diversity of this group is one of the more interesting ones.

 

Reference

 

1 Hoese, H.D., Moore, R.H. 1977.  Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters.  Texas A&M Press.  College Station TX.  Pp. 327.

Snook in the Florida Panhandle

Snook in the Florida Panhandle

Snook… Wait did you say Snook in the Florida panhandle?

Yep… they are not common, but they have seen here.

 

For those who do not know the fish and do not understand why seeing them is strange, this is a more tropical species associated with tarpon.  In the early years of tourism in Florida tarpon fishing was one of the main reasons people came.  Though bonefish and snook fishing were not has popular as tarpon, they were good alternatives and today snook fishing is popular in central and south Florida… but not in the north.

This snook was captured near Cedar Key. These tropical fish are becoming more common in the northern Gulf of Mexico.
Photo: UF IFAS

This fish is extremely sensitive to cold water, not liking anything under 60° F.  They frequent the same habitats as tarpon, mangroves and marshes.  They are euryhaline (having a wide tolerance for salinity) and can be found in freshwater rivers and springs.  Actually, near river mouths is a place they frequent.  The younger fish are more often found within the estuaries and adults have been found in the Gulf of Mexico.  Again, this is a more tropical fish with records in Florida north of Tampa being rare.  In the western Gulf the story is the same, almost all records are south of Galveston, Texas.  Until recently…

 

Hoese and Moore1 cite a paper by Baughman (1943) that indicated the range of the fish had actually moved further south.  One reason given was the loss of the much-needed salt marsh and mangrove habitats from human development.  But in recent years there have more reports north of Tampa.  Purtlebaugh (et al.)2 published a paper in 2020 indicating an increase in snook captured in the Cedar Key area of the Big Bend beginning in 2007.  At first records only included adults, and the thought was these were “wayward” drifters in the region.  But by 2018 they were capturing fish in all size classes and there was evidence of breeding going in the area.  The range of the fish seemed to be moving north.  The study suggests they still need warm water locations to over winter, and, like the manatees, springs seem to be working fine.  But another piece of the explanation has been the reduction of hard freezes during winter in this part of the Gulf.  Climate change may be playing a role here as well.

 

There seems to be other tropical species dispersing northward in a process some call “tropicalization” including the mangroves.  There have been anecdotal reports of snook near Apalachicola where mangroves are becoming more common, and I know of two that were caught in Mobile Bay.  There are mangroves growing on the Mississippi barrier islands as well.  While explaining this during a presentation I was doing for a local group, a gentleman showed me a photo of a snook on his phone.  I asked if he caught it in the Pensacola area.  He replied yes.  When I asked where, he just smiled… 😊 He was not going to share that.  Cool.

 

There is no evidence that snook have established breeding populations are in our waters.  Especially after this winter with multiple days with temperatures in the 30s, it is unlikely snook would be found here.  But it is still interesting, and we encourage anyone who does catch one, to report it to us.

 

References

 

1 Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters. Texas A&M Press. College Station Tx. Pp 327.

 

2 Purtlebaugh CH, Martin CW, Allen MS (2020) Poleward expansion of common snook Centropomus undecimalis in the northeastern Gulf of Mexico and future research needs. PLoS ONE 15(6): e0234083. https://doi.org/10.1371/journal.pone.0234083.

“They Call Me… Karenia brevis”: the story of red tide

“They Call Me… Karenia brevis”: the story of red tide

At the time of this writing, red tide is still lingering off the Pensacola coast.  By the time this is posted it may or may not be.  I have had a few questions about red tide while this has been occurring here, and some misconceptions about it – so, now is a good time to try and set the story straight.

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL

 

Red tide is actually caused by a group of small, single-celled marine plants.  The one responsible for the red tide in the Gulf of Mexico is called Karenia brevisKarenia is a naturally occurring dinoflagellate.  If I were to pull a water sample off of Pensacola Beach right now I would find it there – albeit in small concentrations – say 300-500 cells in a liter of water.  At these concentrations there are no problems.  When we say problems, we mean respiratory problems or fish kills.  See, Karenia is a dinoflagellate that when irritated or disturbed, will release a toxin – brevotoxin.  This toxin is a neurotoxin that is known to kill fish, sea turtles, and marine mammals at high concentrations – greater than 1,000,000 cells / liter.  For humans the issue is more of respiratory and eye irritation.  Though consuming filter feeding shellfish, such as oysters and scallops, during a red tide can cause serious gastrointestinal problems and possibly hospitalization in humans.  This is why the state closes shellfish harvesting when Karenia concentrations reach 5,000 cells / liter.

 

What causes Karenia concentrations to increase from 500 cells to 5,000 cells, or even 1,000,000 cells / liter?

 

The same thing that causes all plants to grow – sunlight and nutrients.

Here is where the first misconception arises.

“Red tides are caused by the increase of nutrients in the ocean due to human activity”.

Not exactly correct.  Red tides have occurred in the Gulf of Mexico since the colonial period, and the colonists certainly did not discharge enough nutrients to spawn a red tide bloom.  No, these blooms occur naturally.  Most form off the coast of southwest Florida.  There the continental shelf extends about 200 miles offshore before reaching the slope to the deep sea.  At this slope there are upwelling currents bringing nutrients from the seafloor to bath these phytoplankton in the warm Florida sun.  This combination, along with some other water chemistry needs, fuel the growth of phytoplankton from a few hundred cells / liter to a few thousand, hundred thousand, or even a million cells / liter – an algal bloom.  At concentrations of 1,000,000 cells or more the water actually changes color to reddish – hence the name “red tide”.

 

However…

Today humans ARE discharging large amounts of organic and inorganic nutrients into local waterways.  These eventually make their way to the Gulf and can enhance a natural bloom from say 10,000 cells / liter to over 1,000,000 – we can make the situation worse.  This typically happens when offshore winds blow the naturally occurring red tides closer to shore to meet our “cocktail of nutrients” and wa-la – an enhanced bloom with enhanced problems.

Dead fish line the beaches of the Florida Panhandle after a coast wide red tide event in October of 2015.
Photo: Randy Robinson

Here in the northern Gulf the conditions to spawn naturally occurring red tides do not typically exist.  What we usually see are the blooms generated in southwest Florida pushed northward but weather patterns.  At the time of this writing, Escambia County is experiencing a red tide offshore at background/very low concentrations (0-10,000 cells/liter).  Though are no reports of fish kills or respiratory issues in humans, but these are happening to our east in Okaloosa, Walton, Bay, and Franklin counties.

 

The state is aware of the not only the red tide situation, but other harmful algal blooms occurring around the state and has a task force to try and address these.  We, of course, can help by reducing the amount of nutrients (fertilizers) we discharge into our local waterways.  This would include not only commercial fertilizers, but any plant and animal waste.

 

References

 

Red Tide Current Status.  2021.  Florida Fish and Wildlife Conservation Commission.  https://myfwc.com/research/redtide/statewide/?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=campaign.