Tuesday, April 22, 2014

Sea Star Wasting Syndrome

There is a new threat to sea stars called ‘sea star wasting syndrome’, which is responsible for mass killings of these important keystone species.  In November 2013, the disease killed up to 95 percent of the sea star populations from Alaska to Orange County.  Little is known about the origins of the syndrome, or even what causes it.  Scientists are trying to determine the cause of this lethal disease before time runs out.


Typically, a sea star infected with the syndrome will have lesions that appear in the ectoderm followed by decay of tissue surrounding the lesions, which leads to eventual fragmentation of the body and death (see picture above).   A deflated appearance can precede other morphological signs of the disease.  “True” wasting disease will be present in individuals that are found in suitable habitat, often in the midst of other individuals that are affected.  The progression of wasting disease can be rapid, leading to death within a few days, and its effects can be devastating on sea star populations. 

“They essentially melt in front of you,” said Pete Raimondi, chairman of the Department of Ecology and Evolutionary Biology at UC Santa Cruz's Long Marine Lab.  The University of California Santa Cruz is currently mapping all events along the West Coast, and people are encouraged to report these sea star wasting events to them.  They classify the syndrome into four categories, with 1 being mild, and 4 being severe.  Pictures and descriptions for the severity of the syndrome can be found here.   

At first, the disease only infected one species, Pycnopodia helianthoides, also known as the sunflower star.  Then the disease began to affect a more common sea star species, Pisaster ochraceus (Robert Paine’s keystone species).  Now, there are about 12-15 species that are dying along the West Coast from sea star wasting syndrome.  And wild sea stars are not the only ones in danger-- in September 2013, sea stars in an aquarium at the Gulf of the Farallones National Marine Sanctuary visitor center at the San Francisco Presidio contracted the syndrome in water pumped from the ocean.  Eels, sculpin and anemones that were in the same aquarium were unaffected.

The probable cause of the disease on the west coast of the US is caused by a pathological agent, such as bacterium (vibrio), although a recent wasting event on the east coast of the US has been attributed to a virus.  Sea star wasting events have also occurred from British Columbia down to the Gulf of California, the Mediterranean and the North Atlantic coast of North America, but not in the Southern Hemisphere.  Some researchers have suggested that Fukushima could be a cause, but the sea stars are being affected on the east coast, so this is not likely.  The ultimate cause is not clear although such events are often associated with warmer than typical water temperatures as was the case for the major die off in southern California in 1983-84 and again in 1997-98.  Sea stars are susceptible to bacterial infection, and warmer water boosts bacteria growth, Raimondi said.  

If the cause for sea star wasting syndrome is not uncovered, ecosystem balance can be disrupted with the disappearance of sea stars.  As we have learned in class, removing Pisaster ochraceus from tide pools causes unchecked population growth of mussels and other organisms.  Also, with global climate change, temperatures will rise in the ocean, which could have significant or even profound effects on populations.  Hopefully the cause of sea star wasting syndrome can be solved before it is too late.

Monday, April 14, 2014

Elephant Seals and Swine Flu

http://media-2.web.britannica.com/eb-media/96/99696-004-058EB9C8.jpg
This awkward looking fella' belongs to the species Mirounga angustirostris, or more commonly, the northern elephant seal.  Male elephant seals can grow up to 14 feet in length, and weigh over 5,000 lbs!  They inhabit the west coast of North America and can travel as far as Japan.  They are excellent swimmers for this is how they get most of their food; hunting fish and squid.  At extremes, elephant seals can dive to depths of 1,500 meters, and stay under water for a whopping two hours!  They can also travel over 12400 miles, annually. Though these giant marine mammals may seem tough, they are susceptible to many diseases.

In 2010, it was discovered that 28 elephant seals had traces of H1N1 anitbodies, suggesting that they were or had been infected with the virus while 2 were tested positive for the infection itself.  H1N1, you may better remember as swine flu, originated from pigs, but had emerged in humans in 2009 as a huge pandemic.  Elephant seals were tested at the beginning of 2010, and tested negative, but upon return from the sea in spring, tested positive.  The figure below maps out this phenomena.
Evidence of exposure to H1N1 in northern elephant seals off central California in 2010 to 2011
In the same study, two adult female elephant seals that tested positive for the virus had their paths tracked in 2008 and 2010.  The data collected can be seen in the figure below.
Tracking data from two adult female elephant seals that tested positive for H1N1 from 2008 and 2010
  This data shows that both seals took similar paths out to sea in 2008 and 2010.  Infection was detected in both seals within days of their return from sea suggesting that they were exposed before their return.  The question is; Where exactly were they and exposed and how?  Though this is not the first time that marine mammals have tested positive for strains of influenza, that question still remains unclear.




References

  1. Tracey Goldstein, Ignacio Mena, Simon J. Anthony, Rafael Medina, Patrick W. Robinson, Denise J. Greig, Daniel P. Costa, W. Ian Lipkin, Adolfo Garcia-Sastre, Walter M. Boyce. Pandemic H1N1 Influenza Isolated from Free-Ranging Northern Elephant Seals in 2010 off the Central California CoastPLoS ONE, 2013; 8 (5): e62259 DOI: 10.1371/journal.pone.0062259
  2. Goldstein T, Mena I, Anthony SJ, Medina R, Robinson PW, et al. (2013) Pandemic H1N1 Influenza Isolated from Free-Ranging Northern Elephant Seals in 2010 off the Central California Coast. PLoS ONE 8(5): e62259. doi:10.1371/journal.pone.0062259
  3. http://www.mnh.si.edu/mna/image_info.cfm?species_id=184
  4. http://www.sciencedaily.com/releases/2014/04/140408213619.htm

Leafy Sea Dragons and Their Amazing Adaptations

The leafy sea dragon, or Phycondurus eques, is a fascinating creature.  Although it sounds fierce, it is a small fish that has no teeth.  They can get up to 18 inches in length and normally live about 5 to 10 years.  They are only found in the southern coastal waters of Australia and they are listed as near threatened because many scientists believe that their species is becoming less common.  Part of this listing is due to the lack of research of their reproduction tendencies.  They thrive in the temperate reefs of Australia by hiding among the boulders, kelp, and seagrasses.  As mentioned before, they don't have teeth, so you must be wondering what their feeding strategy is.  Instead of biting their prey, they suck it down their long tube snout like a seahorse would.  Their diet is mainly composed of small invertebrates such as zooplankton and shrimp as well as larval fishes.  These small fishes must rely on their excellent camouflage to protect them from their predators.  As the name implies, they have many leaf-like protrusions all over their bodies.  This helps them to blend in with the seagrass and kelp in the reefs where they reside.  Their camouflage and color changing ability keeps them safe from their main predators, other fishes.





The above photographs show the amazing body structure of these organisms and their incredible ability to blend in with their surroundings.  Some research that is currently being done looks at their patterns of movement and habitat use.  In this study, 9 adult leafy sea dragons were tracked  near West Island, Australia using ultrasonic telemetry.  Leafy sea dragons lack a caudal fin and are weak swimmers.  Their leafy protrusions are not used for propulsion; they are only for the function of camouflage.  They use their small pectoral and dorsal fins to swim.  These fins are transparent and help them move to create the illusion of floating seaweed.

This research study had the four main goals of describing patterns of sea dragon movement, comparing the proportion of sea dragon positions over different habitats within the available habitats, determining the degree of movement or habitat use varies from day to night, and testing tagging effects on movement.  They found that all fish except one moved within a well defined home range of up to 5 ha. They determined this using the minimum convex polygon method.  They also found that there were long periods, up to 68 hours, of no movement and there were some short bursts of movement.  The fish were found to move about equally during the day and night.  There were no significant differences in movement based on tagging.  No fish were harmed in the removing of the transmitters, but the researchers did suggest that the lack of tagging effect may be due to the tags being attached to bony appendages, away from their bodies.  The sea dragons spent more time over Posidonia seagrass and less time over Amphibolis seagrass than expected.  This was concluded to be simply based on the area of habitat available.  This preference could be due to habitat selection or a response to factor such as prey abundance and water movement. There is still a lot of reproductive stately research that can be done on these organisms.  They are heavily protected just because there are not many of them.  Check out this quick video that summarizes some of their main features and characteristics!



Sources:

Connolly, R. M., Melville, A. J. and Preston, K. M. 2002. Patterns of movement and habitat use by leafy sea dragons tracked ultrasonically.  Journal of Fish Biology. 61: 684-695.

http://www.neaq.org/animals_and_exhibits/animals/sea_dragons/

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

http://kraina-dzikich-zwierzat.blog.onet.pl/tag/australia/

http://www.uwphotographyguide.com 

https://www.youtube.com/watch?v=PkdGlwSy12s

Sunday, April 13, 2014

Accumulation of PFOS in Marine Mammals

Perfluorooctane Sulfonate, or PFOS is a synthetically produced organic molecule used in many household products including lubricants, polishes, adhesives, paints, fire fighting foams, and many more.  This molecule is highly fluorinated, leading to its persistence once it is introduced into the environment. This becomes a problem to both terrestrial and marine species as PFOS is carried by wind and may find it self in even the most remote places in the world (Some Alaskan coastal waters). This brings me to a current study that measured amounts of PFOS in marine mammals.

The scientists wanted to measure PFOS concentrations in marine mammals from many different bodies of water in an effort to gauge its distribution. 247 tissue samples from 15 different species of marine mammals were collected. Locations included the coastal waters of Florida, California, and Alaska, as well as the Northern Baltic Sea and the Arctic. The species analyzed included a pygmy sperm whale, four species of dolphins, two species of sea lions,  six species of seals, polar bear, and the only freshwater species being a southern sea otter. Tissue samples were taken from the liver and the blood in marine species and were acquired from State agencies or university laboratories. The scientists didn’t test marine mammal blubber because PFOS is expected to repel oils/fats so it shouldn’t be found in the fat reserves. It was previously known that concentrations of PCB’s were found in seals in California coastal waters, so scientists expected to find concentrations of PFOS in animal tissue at this same location.
The scientists found that PFOS was in the liver and blood of marine mammals from most the locations. The greatest concentration of PFOS was in a bottlenose dolphin from Sarasota Bay, Fl. (1520 ng/g wet weight). The second highest concentration was found in a ringed seal from the Northern Baltic Sea (475 ng/ml wet weight). This result was unexpected as scientists thought pinnipeds (true seals) would have the lowest concentrations. This is because seals molt annually, which may eliminate compounds binding to structural proteins. 

Overall, the results showed that even in the most remote areas (arctic), PFOS is showing its persistence. PFOS is a wind spread and wide spread chemical pollutant that scientists don't know much about. Although it is structurally similar to other fluorinated compounds, its effects have not been studied on wildlife. Future studies are needed in order to measure the effect this compound has on wildlife. 


REFERENCE:

Kannon, K., Koistinen, J., Beckman, K., & Evans, T. (2001). Accumulation of perofluorooctane 
sulfonate in marine mammals. Env. Science Technology35(8), 1593-1598. doi: 10.1021/es001873w

The California Sea Lion

Who among us has ever been to SeaWorld? I know when I was younger that it was one of my favorite places to go; I loved seeing all of the aquatic life and enjoyed the cheesy shows. One of those shows was similar to what is now called "Clyde and Seamore take Pirate Island," a show that can currently be seen at Orlando's SeaWorld. But when I was little, I confused seals for sea lions and just thought they were the same animals. Obviously  I now know the difference and after discussing them in class it is much easier to decipher between the two.
                                          Cheesy Pirate Show Picture!

Like we talked about in class, sea lions, seals, and walruses are classified in the scientific group called Pinnipeds, meaning "wing foot." Although walruses are easy to distinguish due to their larger body and long tusks, many people tend to confuse seals and sea lions. The main difference is that sea lions have an outer ear flap whereas seals just have a small opening. Sea lions can also use their flippers to stand and to scoot along beaches (refer to the SeaWorld picture above) but seals cannot do this.

The picture above shows a sea lion (left) compared to a seal (right)

To get into more specifics, I found a couple articles which discussed issues the California sea lions are facing today. The California sea lion (Zalophus californianus) are known for their intelligence, playfulness, and noisy barking. Their color ranges from chocolate brown to light golden brown; males are typically darker. Males also tend to be larger and can reach up to a whopping 850 pounds and seven feet in length whereas females grow to 220 pounds and up to six feet in length. The trained sea lions in zoos and aquariums are usually California sea lions. 

They can be found from Vancouver Island, British Columbia to the southern tip of Baja California in Mexico. California sea lions are very social animals and groups often rest closely packed together on land or float together on the ocean's surface. They are opportunistic eaters meaning they can feed on a variety of organisms, some of which include squid, octopus, herring, rockfish, mackerel, and small sharks! Sea lions are preyed upon by orcas and great white sharks.

Although their population is growing steadily, many sea lions have become injured due to malnutrition, domoic acid toxicosis, leptospirosis, cancer, pneumonia, entanglement in debris or fishing gear, etc. In 1998, the Marine Mammal Center diagnosed the first case of domoic acid toxicosis in marine mammals. This is a condition caused by harmful algal blooms which causes the animals to have seizures (like the article Dr. Posner posted in Piazza a couple weeks ago). Although the Center has conducted extensive studies to better understand this specific disease, hundreds of sea lions are affected annually.  

Other articles that I found looked specifically at DA (domoic acid) and its effects on the sea lion. In the first one I looked at, they carried out the study by using adult females and divided them into three different groups which were made up of: acute DA toxicosis, chronic DA toxicosis, and no DA present. It was found that the sea lions exposed to DA had higher eosinophil counts. Basically, what this study showed is that eosinophil counts may be a cost-effective biomarker for DA exposure and may reflect alternations in the hypothalamic and pituitary gland function. This means that DA may have subtle health effects on marine animals and as mentioned by the article Dr. Posner posted, can possibly aid in the study of how human brains work. 

In another study, the unusual occurrence of sea lion mortality was looked at. This was done by looking at both anchovies (which sea lions eat) as well as sea lions feces; this was done by using HPLC-UV. From the data collected, the study provides corroborating evidence that this toxic algal species was involved in this unusual sea lion mortality event. Finally, a third study looked at domoic acid and its effects on the sea lions reproductive success by looking at 209 intoxicated females. The data found indicates that DA can cause reproductive failure in California sea lions through mortality of pregnant females, abortion and premature parturition of pups. Whether the effects of DA on the fetus are direct or indirect was still unclear, though.

So in conclusion, besides being cute and fun to watch, sea lions can be quite helpful to us and should be studied more closely. Hopefully, in the future the effects of DA will become clear and scientists will be able to use the information to help aid humans as well. 

References:

Brodie, E. C., Gulland, F., Greig, D. J., Hunter, M., Jaakola, J., Leger, J. S., & Van Dolah, F. M. (2006). Domoic acid causes reproductive failure in California sea lions (Zalophus californianus). Marine Mammal Science, 22(3), 700-707. 

Gulland, F. M., Hall, A. J., Greig, D. J., Frame, E. R., Colegrove, K. M., Booth, R.K., & Scott-Moncrieff, J. R. (2012). Evaluation of circulating eosinophil count and adrenal gland function in California sea lions naturally exposed to domoic acid. Journal of the American Veterinary Medical Association, 241(7), 943-949.

Lefebvre, K. A., Powell, C. L., Busman, M., Doucette, G. J., Moeller, P. D., Silver, J. B., & Tjeerdema, R. S. (1999). Detection of domoic acid in northern anchovies and California sea lions associated with an unusual mortality event. Natural toxins, 7(3), 85-92. 


Monday, April 7, 2014

Moray Eels & Visual Adaptations

(Image from Wikipedia)

This study wanted to look at the eyes of different species of Moray Eels, and how their eyes have evolved to adapt to their light-changing environments that limit their visual capabilities.

As we know, marine organisms experience a variety of photic conditions in their environments, which in turn affect their sight capabilities. Therefore, the organisms have to adapt to these conditions to survive. This study describes two types of photoreceptors that are found in most vertebrate retinas: rods and cones. (You might remember that I touched on this topic in my Mantis Shrimp blog.) In a little more detail, rods have long segments that tend to dictate scotopic vision, while cones are shorter segments that dictate photic, high activity vision. These two kinds of photoreceptors contain pigments that are made up of an opsin protein and a “chromophoric group” that are based on vitamins A1 or A2.

There are a few things that help marine organisms adapt and cope to their surroundings. First- and probably the most obvious- is that their eye and/or retina have a specific structure; think of it this way: fish that are in little to no light tend to have larger eyes, or they have the ability to reflect light. Second, they have longer segments. Lastly, they have the ability to “switch chromosome class”, or manipulate what kinds of colors they see with their eyes.

In this study, it is mentioned that Moray Eels are thought to be nocturnal predators, with smaller eyes and “well-developed olfactory sense and sensory pores”. These characteristics aid them in their foraging abilities at night. However, some reports have said that Moray Eels forage during the day. (Well that’s contradictory…) If these reports are true, and Moray Eels forage during the day, then that means that they have different visual capabilities in terms of responding to light.

For this experiment, four species of Moray Eels were studied: the Ribbon Eel (Rhinomuraena quaesita), the Laced Moray (Gymnothorax favagineus), the Dusk-banded Moray (Gymnothorax reticularis), and the Slender Giant Moray (Strophidon sathete). These four species were then divided into two groups; the Ribbon Eel and the Laced Moray were the shallow-water group, and the Dusk-banded Moray and the Slender Giant Moray were the deep-water group. The reason that these eels were divided into two groups was because they both live in completely different kinds of habitats- some with more light than others. When the differences were compared, it provided insight as to how the Moray Eels have evolved and adapted to their visual constraints due to their environments.

A few methods were used for this experiment. Tests were done to measure the thickness of each retinal layer; they hypothesized that dim light conditions would produce an increase in photoreceptor and outer layer thickness. Next, they absorbed the spectra that the photoreceptor cells took in by means of microspectrophotometry (MSP). Lastly, the opsin genes of the eels were cloned and sequenced.

*I have added the URL to the pdf version of this paper if you would like to know the details of how the samples were collected, prepared, and followed through. I would go into detail, but there is too much to include in one blog.

The results of the testing showed that the moray eels had what they call a “duplex” retina- one with rods and at least one type of cone cell. Between the four species studied, there was a similar basic structure in their retinas, but there were also differences in the thicknesses in each layer. Below, you can see how the structure of the four species is relatively similar, but the thickness of each layer varies between species.

(Image from the journal article)

Overall, the authors concluded that there was evidence that not all Moray Eels are nocturnal as thought prior to this experiment. The species that they found to be nocturnal were G. favagineus and G. reticularis. The MSP testing concluded that Moray Eels’ photoreceptor sensitivity  were related to the photic characteristics of the specific habitat that they lived in. As a general conclusion, the results of the study proved that Moray Eels have developed an adaptation to different light levels in their environments.


Source:
Wang, Feng Yu, Meng Yun Tang, and Hong Young Yan. "A Comparative Study on the Visual Adaptations of Four Species of Moray Eel." Vision Research 51.9 (2011): 1099-108.
(View the pdf here)

Sunday, April 6, 2014

Electric Skin


The squid is known for it's remarkable ability to camouflage at speeds unmatched by many in the animal kingdom.   Squids have the ability to camouflage at these speeds due to two different mechanisms to produce color and patterns.  Using pigmented organs call chromatophores they can produce yellow, red, and brown color patterns.  Located under these pigments are iridophores, which reflect light and add blue, green, and pink colors to the appearance of skin.   How squids have the ability to be able to control their skins iridescence had remained unknown.   This study looks at the squids ability to change color using iridophores. A video of the pencil squid, Loliginidae, can be seen rapidly changing colors. 

Researchers, Paloma Gonzalez Bellido and Trevor Wardill from the Marine Biological Laboratory (MBL), studied the squid Doryteuthis pealeii to learn more about control over their color change.  By stimulating with different electrical frequencies they found different color shifts. They also found that electrical stimulation of neurons in the squids skin shifted the reflection of light to shorter wavelengths. 
By tracing their nervous network and stimulating them electrically they found that they can shift from red and orange to yellow, green and blue in 15 seconds.   They traced the nerves by tagging them with Dylight 633 and traced them through different axons through different chromatophores.  They also found the the neurotransmitter acetylcholine (ACh) was found in the iridophore layer of skin on the squid.  The concentration of ACh is related to the color shift which supports that the quick change in color is under neuronal control, because of this complete neuronal control researches say it is safe to say that these squids have "electric skin".  
The mechanism responsible for the rapid color change, by iridophores, of squid, cuttle fish, and octopi still remains unknown.  This research will help provide future research with a better understanding of how theses sea creatures are able to change their color at such rapid rates.  Future research on their ability to camouflage could also help the military with their camouflage technology.  Researchers have already removed a protein from bacteria and transferred it to a biofilm that looks similar to a squids skin.  Military researchers say that this is the first step in developing a material that will responds to an external signal.

References:
http://www.sciencedaily.com/releases/2012/08/120827113355.htm
T.J. Wardill, P.T. Gonzalez-Bellido, R. J. Crook, R. T. Hanlon. Neural control of tuneable skin iridescense in squid.