Tuesday, March 29, 2016

Could the "Twilight Zone" Feed the World?

What is the Twilight Zone?
The Twilight Zone is between the depths of 200-1,000m where no sunlight penetrates the water.  The combined biomass of fishes, crustaceans and squids far surpasses that of all the world's current fisheries and it is suspected that the twilight zone contains roughly ninety percent of the world's fish biomass.  It is also said that there may be more than one million species of the twilight zone that have not been discovered.  There are so many creatures that it would be equivalent to 1.3 tons of fish biomass per person on Earth.

Image from Science Daily's News regarding Twilight Zone
Why Is It Important?
The animals of the twilight zone possess a large amount of fishmeal and Omega 3 fatty acids.  Both of these are needed to feed people, but can only be found in parts of the twilight zone, called "no man's water," that cannot be accessed due to a lack fishing rules.  Because there is a lack of understand behind the biological processes that occur in this zone, researchers cannot assess the resiliency of the communities.  Therefore, they would be no way of knowing how to develop a maintenance program should the animals be fished.

The Problem & Solution
It is known that the mesopelagic creatures play major roles in the regulation of the climate.  When they travel to the upper levels at night to feed they release carbon.  This allows for a mechanism for fast transport of carbon, which dampens CO2 's contributions to global warming.  By fishing these animals more, this mechanism could be destroyed.
The solution, however, would be in better understanding the twilight zone's biodiversity.  Things like population controls on recruitment success and each species' role in the food web would need to be learned before this habitat is to be exploited in such a big manner.

As of right now, there are no major efforts being made to begin fishing in the twilight zone.  With a growing demand for the Omega 3 fatty acids, however, the idea becomes more and more viable.  Professor Michael St. John, from DTU Aqua in Denmark states that as the coastal resources are being used up, this idea of fishing in the twilight zone will be of growing interest.  He fears that there will be a "gold rush" of sorts that will be detrimental to the twilight zone communities.  Without knowledge of the communities' resiliencies, this gold rush could lead to completely wiping out entire species.  It would throw off not only local food webs, but could ultimately reduce the species' abilities to help regulate the climate.       


Monday, March 28, 2016

Loggerhead Sea Turtle Nesting Study

Patara Beach is one of the most important nesting beaches in Turkey for the loggerhead Sea Turtle; Caretta caretta. The loggerhead is the most common sea turtle in the Mediterranean. Some of the major nesting sites for this turtle are in Greece, Turkey, Libya and Cyprus.  A recent study has shown information on the nesting activity, spatial and temporal distribution of nesting, nesting and hatching success, nesting density, incubation duration, clutch size, and predation ratio of sea turtles over four nesting periods; 2010, 2012, 2013, and 2014.
Over the four nesting seasons on Patara Beach teams conducted night and morning patrols to determine if sea turtles were laying eggs. The nesting sites were recorded and if the nest showed signs of predation, protection around the nest was set up with metal grates. The number of eggs and hatchlings making it to the sea were recorded as well.
It was found that an average of 179.75 nests were recorded per year. The overall nesting density was 15.50 nests/km while 68.20 loggerhead sea turtle eggs were recorded per nest. The hatching success was 44.05% from these counted eggs and 38.04% made it to the sea. A more detailed result in shown in the table below for each year. 

Table 1. Hatching success and survival of Caretta caretta at Patara Beach over four nesting seasons (N: number of the excavated nests).

Predation was a huge issue in this study. It was found that 53.36% of the nests were affected by predation. Some of the main predators on this beach were foxes, crabs, wild pigs, and wild dogs. These rates and predators differ from other beaches. The metal grate that was used decreased predation and increases the hatchling success. The night patrols conducted also decreases predation pressure. Even after these precautions, if predation is still occurring conservation members can establish an incubation area on the beach. Future research for this study can include further monitoring and conservation studies.


OLGUN, K., BOZKURT, E., CEYLAN, S., TURAL, M., ÖZCAN, S., KARASÜLEYMANOĞLU, K. Ş., & GEROĞLU, Y. (2016). Nesting activity of sea turtles, Caretta caretta (Linnaeus, 1758) and Chelonia mydas (Linnaeus, 1758) (Reptilia, Cheloniidae), at Patara Beach (Antalya, Turkey) over four nesting seasons. Turkish Journal Of Zoology, 40(2), 215-222. doi:10.3906/zoo-1505-8

Sunday, March 27, 2016

The Giant Pacific Octopus


       I have this fascination with octopuses. At first I wanted to talk about how they have four hearts, nine brains,  and blue blood. Two of their hearts pump blood to the gills while the other heart circulates blood to the rest of the body. They have a central brain and a large ganglion at the base of each arm that controls movement, which is why there are nine brains. As for the blue blood, it contains a copper-rich protein called hemocyanin that is more efficient than the hemoglobin we have to carry oxygen at low temperatures and low oxygen concentrations. All of this is very interesting, but during my research I cam across this species of octopus known as the giant Pacific octopus that was even more interesting.

       The giant Pacific octopus grows bigger and lives longer than any other species of octopus. The average size is 16 feet across and 110 pounds, but the record size is 30 feet across and over 600 pounds! I mentioned in a discussion post a little while back that both male and female octopuses die shortly after breeding. The same goes for this species and the average lifespan is about four years old. Females actually don't eat while they are tending to their eggs (brooding), which is months long and die soon afterwards.

 Giant Pacific octopuses have very large bulbous heads that are normally reddish brown in color. They can use special pigment cells found in their skin to change colors and textures to blend in to their surroundings, like chameleons. This is a common characteristic for all octopuses. They usually feed on organisms like shrimp, crabs, lobsters, and fish but due to their large size they have been known to attack sharks. They have sharp beak-like mouths used to tear into flesh. They are nocturnal, so they do all of their hunting at night. They range throughout the Pacific ocean from California to Alaska and west to the Aleutian Islands and Japan. Their population numbers are unknown at this time, but they aren't currently on the endangered species lists. The giant Pacific octopus may not be endangered now, but they are very sensitive to environmental conditions and pollution always poses a threat to these creatures. 

Map: Giant pacific octopus range

                     Giant Pacific Octopus Range=yellow


Galápagos Islands' New Shark Sanctuary


Just recently the president of Ecuador, Rafael Correa, made an important decision for sharks and other marine animals in one of the ocean’s most globally valuable locations. Correa announced that all fishing, mining, and oil drilling is banned in a 15,000 square mile sector of the ocean in the Galápagos Islands. This new protected area has become the largest shark sanctuary in the world and also combines with the rest of the protected areas in the Galápagos Islands to make 32 percent of the area protected (Silva).  An existing marine reserve of 80,000 square miles was created back in 1998. The area had previously allowed local fishing at a small scale, but Correa and the government decided that with global warming affecting the area, illegal shark hunting increasing, and other fishing activities causing negative effects, it was best to establish full protection for the area (Aldred).
Along with the various species of sharks, this new reserve is home to nearly 3,000 species of fish, the only marine iguana in the world, and many other species of mammals and invertebrates (Silva).  Also, around 99% of the land are of the Galápagos Islands is protected and does not allow habitation by humans. The tourism on the islands is also strictly regulated to be sure the environment is kept safe for the biodiverse community it supports (Aldred).
This bold move is an important one for sharks especially. Sharks have seen a decline in population across all of the earth’s oceans. Every year, around 100 million sharks are killed and this new protected site may allow for sharks to safely breed and bring their population numbers back up again. The site is already home to 34 species of sharks and this location is already sought out as a breeding and resting ground for the sharks (Silva).

-Aldred, J. (2016, March 21). Ecuador creates Galápagos marine sanctuary to protect sharks. Retrieved March 27, 2016, from http://www.theguardian.com/environment/2016/mar/21/ecuador-creates-galapagos-marine-sanctuary-to-protect-sharks
-Silva, C. (2016, March 21). Ecuador Announces World's Biggest Shark Sanctuary In Galápagos [PHOTOS]. Retrieved March 27, 2016, from http://www.ibtimes.com/ecuador-announces-worlds-biggest-shark-sanctuary-galapagos-photos-2340421

Friday, March 25, 2016

Killer Whale Hunting Strategies

The first thing that comes to mind for me when someone talks about orcas is Shamu. Although they look beautiful and majestic, these are not animals that you would want to get in the water with; they have the name "killer whales" for a reason. I knew a little about these animals and how they hunted in pods, but not much, so I decided to do some research on this topic

Research was done for a few years at Punta Norte on the east coast of Argentina, that primarily focused on the social dynamics of killer whales, Orcinus orca, when hunting marine mammals. These predators help to show association patterns and foraging behaviors, and paint a pattern to understanding hunting efficiencies. In general, killer whales are rather smart and clever when it comes to hunting their prey. It has been documented that a pod of these predators will swim in a line towards an ice floe that a seal is sitting on. They will create a large enough wave to tip the ice floe or flip it entirely and through the seal into the water for the whales to eat. Another strategy that has been used is when they attack an animal that is much larger than themselves. An example of this is a large number of the orcas ganging up on a baleen whale and attacking it from all sides.

The researchers for this study identified 13 different killer whales by recognizable features on their dorsal fins. The objective was to study the details of predator and prey interaction and foraging strategy of the whale population of Punta Norte. This allowed the researchers to observe the behavior of prey and predator directly, and to gain data over a span of two years. All of this data helped to indicate that the killer whales at Punta Norte hunt preferentially in the most productive areas and pursue the prey-type that is the easiest target. It was also found that whales within the same pod share food, and that one whale within each pod will do most of the hunting.

The hunting area of the orcas was divided up into 12 quadrants, each roughly 580m wide. Behavior was classified into categories consistent with earlier studies that had been done. Each time a whale would surface, it's behavior, position, and direction of travel was recorded. During 'patrol' behavior a whale would travel just beyond the surf zone parallel to the coast for roughly 20m or more. 'Hunting' was defined as nearshore intentional scanning, pursuits, close approaches and/or standing in the presence of potential prey.

A total of 13 whales were identified in three separate pods. The pod that was seen the most was made of two adult males (B-pod). The pod that was seen the second most was named A-pod and consisted of two adult females and five subadults. The third pod (C-pod) was made up of one adult male, one adult female, and two subadults. This C-pod was seen the least. This whales were seen over a two year time span and a total of 468 hours.

In general for all the pods, most of the hunting took place in quadrant 10, which had a deep channel in the middle that was surrounded by reefs. Of the attacks that were recorded, approximately 97% were directed towards southern sea lions, 2.4% were directed towards southern elephant seals, and 0.6% were directed towards birds. Of the attacks directed towards southern sea lions, the majority (65.5%) were directed towards the pups, which helps to indicate that the whales tend to go for the easier catch.

When the whales would catch a sea lion pup, it was held by an appendage and swung back and forth so that it would hit it's head on either side of the whale's head. It could also have been shaken very violently. The pup would then be taken off shore and was either not observed again, or was released and then pursued in open water by all the whales present. This helps to show that the killer whales tend to share the food with the rest of the pod.

After this study, there are several things that are now certain. These killer whales hunt in very specific locations with specific strategies, the cost of competing over high quality sites could be very high, and whales within the same pod will work together to get the prey, and then will share the food.


Friday, March 18, 2016

Singing about Science

                In sixth grade, I went on a three-day field trip to Cuyahoga Valley National Park.  While the trip was loads of fun and we learned a lot about the environment, the thing that stuck with me the most was this annoying song about watersheds.  Naturally, when we started talking about watersheds and estuaries in class, the song came to mind (and wouldn’t get out of it).  So I’ll share some new discoveries about estuarine populations while I’m humming.
                As we progress to larger species in class, I find myself disregarding the smaller marine organisms, but the health of zooplankton is significant in estuaries.  Research was conducted by David and eleven other researchers last year to determine if the unique habitat of estuaries caused a particular structure in zooplankton populations.  Water samples were taken from the Gironde Estuary in southwest France to be analyzed.  They found that the upstream-downstream gradient of the estuary related to the distribution of species while abundance within a set species had a trend with estuarine depth – subtidal versus intertidal.  The intertidal zone is especially attractive to zooplankton due to food availability.  With the numerous challenges to estuaries in mind, disruptions to these populations of zooplankton in the intertidal zone or the availability of food in this zone could have significant implications along the trophic cascade. 
                While considering the changes that estuaries undergo due to the challenges that they face, a bit of research about the adaptive abilities of Olympia oysters (Ostrea lurida) caught my attention.  Low salinity concentrations is linked to climate change, so this was the major aspect of change in the ocean water that they considered.  Bible and Sanford designed a fascinating study.  They collected oyster offspring from the Tomales Bay and San Francisco Bay estuaries and raised them in the laboratory.  A population of these lab-raised oysters were then placed in the bay they originated from and a second population was placed in the opposite bay.  This was completed at three different sites, and at two of the three sites the “local population” oysters survived better, indicating estuary-specific adaptation.  A similar experiment was completed with second-generation lab-raised oysters, and the results showed that the oysters descending from the estuary with the lowest salinity survived low salinity challenges in the lab more often than the other oysters.  I found this research to be well designed.  I hadn’t thought about this idea before, but this shows that we need to evaluate how populations are adapting to the challenges that their estuarine home is facing before we take extreme measures to restore the estuary to its original condition.
                That’s all for now!  If that wasn’t interesting enough, tune in next time for a song about something else.
Bible, J.M., Sanford, E.  (2016).  Local adaptation in an estuarine foundation species: Implications for restoration.  Biological Conservation.  193, 95-102.  <http://www.sciencedirect.com/science/article/pii/S0006320715301634>.

David, V. et. al.  (2016).  Estuarine habitats structure zooplankton communities: Implications for the pelagic trophic pathways.  Estuarine, Coastal, and Shelf Science.  Published online.  <http://www.sciencedirect.com/science/article/pii/S0272771416300221>.

Wednesday, March 16, 2016

Tetrodotoxin (TTX)

Tetrodotoxin (TTX) is a poison that is produced by most commonly puffer fish as well as many other organisms. It is a virulent poison that acts by blocking the impulses of nerves along axon terminals. Which ultimately can lead a victim to die from paralysis. The specific channels that this toxin blocks is the sodium ion channels. TTX is larger than sodium, which is why it blocks the channels so easily. To give some perspective, sodium binds in the channels in nanoseconds whereas TTX is bound for tens of seconds in the channels.

There are a couple different ways for humans to get harmful doses of TTX one of the common ways of receiving a lethal dose of TTX is by digestion. In Japan puffer fish is a delicacy call fugu. Chefs prepare this dish with special certifications by the government so they do not prepare toxic flesh, liver, and gonads. But despite the precautions many cases of TTX poisoning are from people ingesting fugu (puffer fish).  Another way to get TTX poisoning is by coming into contact with the skin of Atelopid frogs, and certain newts, sea slugs, as well as being bitten by a certain gastropod mollusks. It has been verified that 1-2 mg of purified TTX can be lethal to a human.

Pufferfish or Tetraodontidae is a carnivore that contains the TTX toxin as mentioned above which makes the fish foul tasting and often is deadly to the predator that ate the pufferfish. To humans, pufferfish are approximately 1,200 times more poisonous than cyanide. And there is approximately enough TTX toxins in one pufferfish to kill about 30 humans. There is no known antidote for TTX poisoning only symptoms including numbing of the mouth and its surrounding areas, nausea and numbness.

I find that animals that are extremely toxic to any organisms are extremely interesting and I would like to find out more about this specific toxin and as to why they are in specific animals. In my presentation I would like to discuss more of the animal groups that the Tetrodotoxin occurs in.