Sea Turtles

Figure 1: Sea turtle swimming through the water. (Available from: http://nsbturtles.org/)

Sea turtles are considered one of the longest living species that is known today (Defenders of Wildlife, 2016).  These turtles vary in color, and are not able to contract their front legs like most other turtles.  Sea turtles dietary needs vary, from seaweed to crabs.  Most of this food can be found in the coral reefs within the shallows.  They spend most of their life within the water, however, they reproduce on the sandy beaches.  However, these sea turtles are being severally affected to the point of being classified as critically endangered or vulnerable (World Wildlife Fund, 2016).  There are many factors that are having a major effect on the population size of many different species of sea turtle.  These factors include bycatch, disease, habitat loss, egg predation, pollution, and nutrient loss (Lucchetti et al., 2016).  However, for the sake of this blog I will be focusing on two main areas that seem to be affecting the population of sea turtles: 1) Tumors and 2) habitat loss.

Tumors

Figure 2: A sea turtle with a massive tumor growing off its face (Available from: https://www.nwhc.usgs.gov/hfs/Globals/Products/Tumors-in-Sea-Turtles-Final-PDF.pdf )

                One of the causes for the population decline in sea turtles is the disease fibropapillomatosis (Work and Balazs, 2013).  This disease is mainly detectible by the tumors that grow on the sea turtles flippers, eyes, neck, corners of their mouth, and sometimes on their internal organs.  Since these tumors grow all over the turtles bodies, they can cause great problems.  The tumors that grow within the mouth and trachea can cause many problems.  It can cause the turtle to be unable to eat, or it can close the trachea thus causing the sea turtle to aspirate.  The tumors can also cause the turtles to become blind, and generally these symptoms can lead to death.  Research is being conducted in order to see what the main cause for these tumors is. 

                Right now there are three main theories to what is causing these tumors.  The first is that environmental contaminates (such as certain types of metals) may be causing this disease; however more research is needed in order to better understand the mechanism behind this theory (Carneiro da Silva et al., 2016).  The second theory is that flatworms may be causing the tumors (Work and Balazs, 2013).  In fact research has shown that 100% of the turtles affected by fibropapillomatosis are infected by flat worms.  The last theory is that it may be a virus.  Certain research has been able to support this, by showing that when tumor free turtles are introduced to contaminated water, (contained sea turtles with tumors), they later were found to have this disease. 

                Therefore, these tumors are a major problem for sea turtles that must be dealt with.  However, lots of future research is needed in order to completely understand what is causing this disease, and what we may be able to do to help.        

Habitat loss

Figure 3: A sea turtle crawling across the beach, while tourists look on, resorts can be seen in the background showing habitat disturbance (Available from: https://www.youtube.com/watch?v=VwULuR9txcg)

 

                Habitat loss seems to be one of the major factors that is affecting sea turtle population sizes.  As coastal regions continue to be impacted by humans, the sea turtles have less areas to reproduce as well as less areas to find their food and dietary needs.  This destruction is caused by many factors including pollution, development (mainly of resorts and homes), fisheries, and newly introduced invasive species (Santos et al., 2011).

                In 2011 it was found that approximately 65% of sea grass areas and coral areas were destroyed (Santos et al., 2011).  These areas are the main feeding grounds for the sea turtles.  Since the sea grasses seem to be greatly affected, some research was conducted by Santos et al. to see how the decreasing availability of food affected the sea turtles.  They found that as the sea grasses were diminished, the diet of the sea turtles was also diminished, thus causing for the sea turtles to have less access to the nutrients they needed in order to stay healthy.

                Other research was done in order to see how development on the coast lines is affecting the reproduction of the sea turtles (García et al., 2015).  As more developments on the coast line and as the sea line continues to rise, there is less available beach area for turtles to reproduce.  The estimates in 2007 showed that the sea level was going to continue rising by 4.2 mm per year, until no nesting habitats of sea turtles were available.  As you can probably guess this would have adverse effects on not only the reproductive success as well as their survival overall.  Some research conducted in 2015 wanted to see how three different rises of water would affect the reproduction of the sea turtles.   It was found that a rise of 5m or more would have the greatest effect on sea turtles, by causing a loss of 54% of the beach area.    

               As it can be seen, all of these factors are having major effects on the survival and reproductive success of sea turtles.   Hopefully, as more research is conducted more ways to try and mitigate these factors will arise, thus allowing us to find ways to help the sea turtles.    

Figure 4: A sea turtle eating some sea grass (Available from: http://marinecreaturesstockphoto.com/creature-feature/ ) 

Words: 798

Citations:

Carneiro de Silva, Cinthia; Klein, Roberta Daniele; Barcarolli, Indianara Fernanda; and Bianchini, Adalto.  2016.  Metal contamination as a possible etiology of fibropopillomatosis in juvenile female green sea turtles Chelonia mydas from the southern Atlantic Ocean.  Aquatic Toxicology, 170: 42-51 DOI: 10.1016/j.aquatox.2015.11.007

García, Yuritzi Calvillo; Ramírez-Herrera, María Teresa; Delgado-Trejo, Carlos; Legorreta-Paulin, and Gabriel; and Corona, Néstor.  2015.  Modeling sea-level change, inundation scenarios, and their effect on the Colola Beach Reserve- a nesting-habitat of the black sea turtle, Michoacán, Mexico.  Geofísica Internacional, 54: 179:190 DOI: 10.1016/j.gi.2015.04.013

Lucchetti, Alessandro; Pulcinella, Jacopo; Angelini, Valeria; Pari, Sauro; Russo, Tommaso; and Cataudella, Stepfano.  2016.  An ineraction index to predict turtle bycatch in a Mediterranean bottom trawl fishery.  Ecological Indicators, 60: 557-564 DOI: 10.1016/j.ecolind.2015.07.007

Santos, Robson G.; Martins, Agnaldo Silva; Farias, Julyana da Nobrega; Horta, Paulo Antunes; Pinheiro, Hudson Tercio; Torezani, Evelise; Baptistotte Cecília; Seminoff, Jeffrey A.; Balazs, George H.; and Work, Thierry M.  2011.  Coastal habitat degradation and green sea turtle diets in Southeastern Brazil.  Marine Pollution Bulletin, 62: 1297-1302 DOI: 10.1016/j.marpolbul.2011.03.004

Work, Thierry; and Balazs, George H.  2013.  Tumors in Sea Turtles, The insidious menace of Fibropapillomatosis.  Health and Disease, 44-47

World Wildlife fund. [Internet] 2016.  Green Turtle. [Cited March 7, 2016]  Available from: http://www.worldwildlife.org/species/green-turtle

Photos:

Endangered sea turtles return to New Smyrna Beach from May through September after a long migration in the Atlantic Ocean.  NSB Turtle Trackers Available from: http://nsbturtles.org/

January 2015 Creature Feature The Endangered Green Sea Turtle.  Creature feature this month.  Available from: http://marinecreaturesstockphoto.com/creature-feature/

Cancun sea turtle going back to the beach after laying 98 eggs.  Screenshot from Youtube.  Available from: https://www.youtube.com/watch?v=VwULuR9txcg