HARMFUL ALGAL BLOOMS AND YOU!

Harmful Algal Blooms (HABs) occur when usually harmless phytoplankton--microscopic or very small, photosynthetic marine organisms--reach high densities. Their numbers rapidly increase in a given area to the point where they go from harmless to hazardous.

The hazard they present can come from their anatomy, physiology or metabolism.

ANATOMY
Some diatoms, like those pictured below, have sharp spines that can cause fish to suffocate by getting lodged in their gills and causing acute inflammation. Some microscopic algae produce mucus, clogging gills and leading to fish's respiratory failure.

Fish with spiny diatoms in its gills.
(Image from www.bigelow.org)
 

The spiny diatom Corethron pennatum 
(image from www.phys.org)

PHYSIOLOGY AND METABOLISM
Some phytoplankton affect theorganisms that prey on them by interfering with feeding. The mucus the phytoplankton produce might make them unpalatable or indigestible. Others have such low nutritional value that the organisms that eat them actually starve to death!

Perhaps the most well-known HABs are those that produce toxic blooms. We commonly call those "red tides" although the water color isn't necessarily red, but can be yellow, green, or brown due to the sheer numbers of phytoplankton. Some of the algae that cause the color changes are capable of producing powerful toxins that are harmful or deadly to other species. The toxins may kill fish, injure marine invertebrates, and cause human illness or death from ingesting shellfish that have accumulated the toxin in their tissue. Some of the human illnesses from ingesting contaminated seafood include Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Paralytic Shellfish Poisoning (PSP), and Ciguaterra Fish Poisoning (CFP).

A "red tide" bloom.
          From The Baltic Sea Portal (Itameriportaali).

While phytoplankton use photosynthesis to create their food source and release oxygen into the environment, their high productivity and short lifespan means a high turnover of biomass---lots of dead microalgae. As those decompose, they quickly deplete all the oxygen in an area, resulting anoxia---low or no oxygen in the surrounding water. Their decomposition also results in the formation of toxic sulfides in the water. The lack of oxygen and production of sulfides creates a deadly scenario for most marine life that can lead to massive fish die-offs.

Fish die-off due to anoxic conditions from a HAB
(photo from G. Pitcher, via www.bigelow.org)

PREDATION
At least one species of phytoplankton, Pfiesteria piscicida, is actually a predator, killing and then feeding on fish in the waters they inhabit.

WHO CARES?

We all should. HABs affect everyone! They're a global threat to living resources, fishing, tourism, and human health because the number and intensity of these events appear to be increasing in many countries. In the last two decades, HABs are estimated to have caused as much as $1 billion in losses to coastal resources and communities (NOAA). Check HERE for more information on the socioeconomic impacts of HABs (WHOI).

Preventing and eliminating harmful algal blooms is no easy tasks. There are numerous factors that influence the formation, distribution and duration of blooms. It’s difficult to control one factor in the environment, let alone all factors for all algae in all locations. In addition, any action taken to prevent or to remove a bloom has consequences for the other organisms in the environment.

A combination of factors contribute to the development of HABs such as the presence of  nutrients, warm temperatures and lots of light. Rising ocean temperatures from climate change, increased nutrient run-off from land due to poor land-development practices and a loss of wetlands, and the break down of marine food chains due to overfishing all play roles and are all increasing, so we can most likely expect to see more and more HABs in the future. 

Researchers are constantly trying to gain a better understanding of HABs to help find ways to control their development and reduce their impacts. Early detection of their formation is critical to prevent impacts to human health by issuing fishery and beach closures in impacted areas. 

If that makes you feel helpless to do anything about HABs, you're NOT! You can help by asking state and local lawmakers to implement better land-use planning and wetland preservation to protect coastal water quality, learning the facts about climate change, and demanding good, research-based science, not hype, someone's political- or financial-gain, or fear, drive government decision-making.



FOR MORE ON HABS, CHECK OUT THESE SITES

• Bigelow Lab for Ocean Science  http://www.bigelow.org/edhab/help_hab.html
• Environmental Health, 2008. Impacts of climate variability and future climate change on harmful algal blooms and human health. http://www.biomedcentral.com/content/pdf/1476-069X-7-S2-S4.pdf
• Environmental Protection Agency http://www2.epa.gov/sites/production/files/documents/climatehabs.pdf
• National Oceanic and Atmospheric Administration, National Ocean Service  http://oceanservice.noaa.gov/education/lessons/bad_algae.html
• Texas A&M, Ocean World Online Textbook http://oceanworld.tamu.edu/resources/oceanography-book/harmfulagalblooms.htm
• Woods Hole Oceanographic Institute https://www.whoi.edu/redtide/home

Oh, Those Wild, Sexy Reef Fish!

WARNING: If you're easily offended by "unnatural" phenomenon like sex-changes this is NOT the post for you to read! It's all about the all-too-common occurrence on the reef of fish undergoing a sex change.

For the rest of you, read on. This is fascinating stuff!

Out in the real world, meaning the one we humans haven't artificially insulated ourselves from with technology, where the realities of life and death are governed by chemical and physical laws, animals must stick to a strict budget. It isn't a financial budget, but an energy budget that must be balanced. Every living organism, for its survival and the survival of the species, does whatever it takes to optimize energy use.

Energy In = Work to Survive 

Where:

Energy In = the number of useable calories an organism takes in, and

Work to Survive = using those calories for growth, finding food, shelter, defending your shelter, finding a mate, the process of mating, and repair of tissue damage or injury incurred from any of the above activities.

If you don't take enough energy in, you can't do all of the activities needed to survive. The whole point of survival in the animal kingdom is to reproduce. The more offspring you have, the more likely your genes are to survive through subsequent generations, thereby making you somewhat immortal.

As anyone on a budget can tell you, making sure that what you take in can cover all your expenses, you have to make some trade-offs. The more you spend on having fancy things and defending them, the less you have to wine and dine potential mates. But, without those accoutrements that announce your relative fitness, even your superiority, to prospective mates you won't get that opportunity.

No surprise that the perfect balance is different for males and females. In most species, females do the majority of the work in the offspring department. Whether they carry those embryos internally, or scatter them to the currents in the ocean, they still have the greater energy investment in egg production. Their eggs provide all the initial nutrition and organelles, as well as DNA, to the newly fertilized offspring. Sperm are packs of DNA and nothing more. It doesn't take much energy to make them.

This difference in energy expenditure for reproduction is one of the driving forces behind sexual dimorphism: differences in physical appearance between the males and females of a species. In particular, this accounts for size differences: When males have to protect territory or a harem from other males, spending energy to get bigger makes sense. When you can swim in, release lots of sperm, and leave, being small and quick is beneficial. Likewise, if a female produces many eggs, a far more energy intensive undertaking than sperm production, being large is beneficial.

Since "survival of the fittest" doesn't really mean not dying, but actually reproducing, "success" in the natural world means producing healthy offspring that go on to be successful themselves, the more offspring you produce, the better. If a female with a larger body cavity can produce more eggs per reproductive episode, and the more eggs produced increases her potential reproductive success, it's to her benefit to be a big female. Conversely, if larger males have greatly increased reproductive success (i.e. gain control of a harem), it would be beneficial to be a big male.

This is known as the size advantage model, developed by Ghiselin in 1969, that states "if an individual could significantly increase its reproductive success after reaching a certain size by being a different sex, it would be to their advantage to switch to that sex." And on the coral reef, they do!

Here are some of the brilliant reef fish that can change sex--sometimes in a matter of a few hours.

The Blueheaded Wrasse

The cleaner wrasse, Labroides dimidiatus. Typically, live in harems with a dominant male around cleaning stations. When the male is removed, the largest female becomes a functional male. The Blueheaded wrasse, Thalassoma bifasciatum, do not form harems, but the dominant or terminal males take temporary control of spawning sites. Removal of terminal males results in the largest females transforming.

 

Moonheaded Wrasse

When the largest female turns into a male, it is called Protogyny, Almost all the sex-changing species in the Caribbean are protogynous hermaphrodites, switching from females to males after reaching a certain size, age, or when the harem's male is removed. Some other examples are the parrotfish, Spanish hogfish, Holacanthus tricolor (the rock beauty angelfish), and some damselfish.

 

Rock Beauty

Clownfish in their anemone

Anemone fish, like the skunk anemonefish Amphiprion akallaopisos, and clownfish, like Nemo, are protandrous. They change from male to female. Anemonefish live in monogamous pairs composed of a large female and a smaller, functional male. The pair may share their anemone-home with other, small, stunted (not sexually developed) males (juveniles; all anemonefish are born male). When the female is removed, the functional male changes sex and the largest juvenile becomes a functional male. Snook (Centropomus undecimalis) are one of the few known Caribbean protandrous fish.

Some reef fish, like gobies, can actively change sex in either direction. This lets them maximize their genetic fitness under any environmental situation.

There are many amazing things in the natural world. We'd do well to study them, be amazed by them, and learn from them. Our lesson from these fish? Embrace change, especially when it benefits us!

For More Info on Sex Changing Fish:

DeLoach, Ned and Paul Humann (1999). Reef Fish Behavior: Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. 359 pp.

Hendrickson, Robert (1984). The Ocean Almanac. Doubleday. New York, NY. 446 pp.

The National Audobon Society (1997). Field Guide to Tropical Marine Fishes: Caribbean, Gulf of Mexico, Florida, Bahamas, Bermuda. Alfred A. Knopf, Inc. New York, NY. 720 pp.

 

Rice, Aaron N. (undated). Physiology of Sex-Change in Reef Fish. Available at: http://www.bio.davidson.edu/Courses/anphys/1999/Rice/Rice.htm

 

What's Up with Waterspouts?

What's up with waterspouts? Sometimes it's fish that go up with them, sometimes periwinkles, and sometimes just clay particles that mix with the condensed water in the funnel cloud and then fall as red water, also known as a "rain of blood." But more on that later...

First, let's take a closer look at this spectacular phenomenon.

Fair-weather waterspout

For as long as humans have observed and recorded events on and around large water bodies, the appearance of waterspouts has evoked superstition, fear, and even contributed to the romance of the sea. Sailors have attributed the phenomenon to sea dragons, sea serpents, and evil spirits. Arabian sailors believed them to be manifestations of Jinees--powerful spirits capable of assuming various forms.

The reality behind the myths and mysteries is twofold: some waterspouts are tornadic, formed from the same factors that result in terrestrial tornados, and others are fair-weather spouts.

Tornadic waterspouts drop down from thunderstorms, squall lines, or the leading edge of advancing cold fronts. Like the typical twisters seen in movies and on episodes of Storm Chasers, tornadic spouts have dark, sinister funnels spawned from large, turbulent "parent clouds."  These are seen most frequently at middle latitudes, off the lee shores of large landmasses where cold continental air sweeps over warmer water. Tornadic waterpouts are often bona fide land tornados that go to sea or cross large inland bodies of water. Tornadic spouts can form over water and come ashore as true tornados, and alike true tornados, they can abate and come back more than once.

Fair-weather waterspouts arise solely over water. They develop at sea level and climb skyward when humid, superheated air circulates convectionally with cooler overhead air. Fair-weather spouts tend to be smaller and of shorter duration than the tornadic variety and are considered relatively harmless. These prevail in equatorial regions, although they do occur in all latitudes during the transition seasons of spring and fall.

In the northern hemisphere, tornadic waterspouts rotate cyclonically (counter clockwise) with wind speeds of up to 130 mph. They can be quite long-lived, lasting on average 15-30-minutes. Their advancing speeds tend to be rather slow (less than 5 mph). Conversely, fair-weather spouts travel faster over a given distance, moving at speeds up to 30 mph, but their rotative speed is much lower. They also dissipate quite quickly, rarely lasting as long as 20-minutes. Fair-weather spouts may rotate in either direction, depending on the nature of the convection currents that form them.

Both types of waterspouts are quasi-seasonal at best. They're seen more frequently in temperate latitudes between May and October, and more in the deep tropics from October through March. Exceptions abound throughout the year in any locale.

String of waterspouts forming over Charlotte Amalie Harbor,
St. Thomas, USVI (2007).

Tornadic waterspouts are more dangerous and destructive since they form from storm clouds. The same dangerous conditions found with severe thunderstorms---strong winds, large seas, hail, and lightening--are commonly found around tornadic spouts. While tornadic spouts are the more dangerous of the two types of spouts, care should be taken when encountering either one of these natural phenomena.

Cool Waterspout Facts

• The Great Waterspout of 1896 formed off Martha's Vineyard on August 19th of that year. Photographs and first-hand accounts from veteran mariners verified the spout was 144 feet thick and 3600 feet high. The spout formed not once, but three times within 45 minutes.

The Great Waterspout of 1896. (Photo from NOAA Image Library.)

• A Tampa, Florida waterspout (June 13, 1952) caused over $75,000 in property damage when it came ashore with 100 mph winds. 

• On September 5, 1935, a tornado/waterspout formed near Norfolk, Virginia and rampaged across Tidewater and Hampton Roads, where it flung railroad cars off their tracks before moving out to sea over the Chesapeake Bay.     

• Waterspouts can form over freshwater in rivers and lakes, as well as saltwater bodies. Several have formed on the Hudson River over the last 100 years.

• The longest recorded waterspout occurred off Eden, Australia on May 16, 1898. Theodolite measurements verified its height at 5,014 feet (although it was only 10' in diameter).

• The widest waterspout on record was 700' wide, formed at Blunt's Reef, California on November 14, 1914.

• Waterspouts have resulted in "rains" of fish, frogs, lizards, tadpoles, and periwinkles, most likely due to waterspouts coming ashore over low-lying marshlands and swamps.

• Some waterspouts have resulted in a "rain of blood" when the spout churns up a nearby stretch of red mud or clay, mixing the particles with the spouts condensed water droplets that fall when the spout dissipates.

 Sources

All At Sea. http://www.allatsea.net/caribbean/water-spout-are-they-dangerous/

Hendrickson, Robert. 1984. The Ocean Almanac. Doubleday Press. 446 pp.

National Oceanic and Atmospheric Administration. www.noaa.gov

Mystery of the Fish Eye

If you're on Facebook you probably saw the picture of the giant bloody eyeball that washed up on a Florida beach a few weeks ago. Speculation on the source of the softball-sized eye ranged from the reasonable (giant squid or whale) to the unlikely (Big Foot).

Photo by Carli Segelson, Florida Fish and
Wildlife Conservation Commission

Based on the eye's color, size and structure, along with the presence of bone around it, scientists concluded the eye came from a swordfish. They also observed straight cuts around the perimeter, suggesting the eye had not been ripped out in some deepsea wrestling match but removed with a knife. Most likely, the eye was cut out and discarded by a fisherman. Was it a fisherman with a keen sense of humor who thought "won't this freak someone out?" as he tossed it overboard? We may never know.

Giant squid attacking a bait squid.
Photo from National Geographic.

Most people don't realize how big a swordfish or marlin eye can be because most of it is inside the head. As impressive as the eye's size is, it pales in comparison to the giant squid's dinnerplate-sized eye that comes in at 3 times the diameter of the swordfish orb. Scientists speculate the larger eye allows the squid to detect the shimmer of bioluminescent organisms in the dark of the ocean deep. The glitter of light could indicate the approach of the squid's only predator, the sperm whale.

Fish eyes, for the most part, work similar to our eyes. They have rods and cones, and light enters through a cornea and passing through the pupil to reach the lens. Most fish have a fixed pupil size, but cephalopods, like the giant squid, have a pupil that adjusts size and shape: it's w-shaped when contracted and round when fully dilated. There isn't much difference in refractive index between the water and the cornea--light passes in a straight line, no bending as it does when passing through air into our liquid-filled eyes. Human eyes are adapted to accomodate the differences in refraction between air and water and so are more concave than most fish eyes. That's why we need to wear a mask to see underwater, but fish don't.

Four-eyed fish, http://aha.miraclegreat.com/

 The four-eyed fish might just be the winner for the most unusual eyeballs in the aquatic world. These fish feed on terrestrial insects at the surface so they need to see underwater, where they live and in the air, where they feed. Their two eyes (yes, 4-eyes is a misnomer) are raised above the top of the head and divided in two different parts, allowing them to see below and above the water surface at the same time. The fish floats at the water surface with only the lower half of each eye underwater. The two halves are divided by a band of tissue and the eye has two pupils connected by part of the iris. The upper half of the eye is adapted for vision in air, the lower half for vision in water The lens of the eye also changes in thickness top to bottom to account for the different refractive indices of air versus water. The two pupils allow the 4-eyed fish to search for the food above the water while keeping an eye out for predators below the water at the same time. It also makes them really difficult to catch!

56' of Sea Serpent

What's the longest fish on record? The oarfish, Regalecus is the longest bony fish in the oceans today, holding the record of 17 meters (56') in length. Seems like something that big would have a hard time hiding, so why have most people never heard of or seen something that large?

Some sailors in the US Navy pose with a dead oarfish (1996; from Wikipedia)

Oarfish live at depths up to 3,280 feet (1,000 m), although they're more typically found at around 656 feet (200 m). They rarely venture to the surface unless they're injured or dying. Occasionally, one of these giant eely fish will be tossed onto a beach after a storm. Their eggs can be seen during spawning season from July to December in the northern hemisphere. They release the brightly coloured, buoyant eggs (up to 6 millimetres (0.24 in) across) which are incorporated into the zooplankton. The eggs hatch after about three weeks into highly active larvae that feed on other zooplankton.

Drawing of the sea serpent-like oarfish

With their long, tapering body, smooth silvery skin (they don't have scales), and red dorsal fin that runs from the eye down the entire length of the body, oarfish are the most likely source of tales of sea serpents. Their dorsal fin is composed of 400 rays, the first 10-12 of which are elongated and flow from the head like a mane. Their pelvic fins are also elongated and end in a fleshy tab. It was once believed they rowed themselves through the water with these pelvic fins, thus the name oarfish. They actually swim by undulating their long dorsal fin while keeping the body straight (as do sea horses). Similar to sea horses, oarfish have been observed swimming in a vertical position in what is believed to be a method used to search for prey.

 

A dead oarfish washed up on a beach in Perth, Australia

Oarfish are found in temperate to tropic seas, but as mentioned, they're rarely seen because of their preferred depth. In fact, the first time a swimming oarfish was caught on video was in 2001! You can see parts of that on this You-Tube video.

Oarfish have no teeth and feed on plankton, so they're no threat to humans, and humans are no threat to them since their mushy flesh isn't very tasty. Still, I might think twice about jumping into the water with a 56' long fish!!
 

Oarfish. Image from Wikipedia.

 

 

For more information on the oarfish, see:

 

Hendrickson, R. (1984). The Ocean Almanac. Doubleday, NY. 446 pp.

http://www.itsnature.org/sea/fish/oarfish/

http://www.seasky.org/deep-sea/oarfish.html

http://en.wikipedia.org/wiki/Oarfish