Contacts

IBAP

Website: http://ibapgbissau.org/

Email: geral@ibap.com

Address: Av. Dom Settimio Arturro Ferrazzetta, CP 70, Bissau, Guiné-Bissau

 

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As sea turtles occupy different environments in different development stages; such as the sandy beach where they hatch and nest, coastal areas used for foraging, and the open ocean which they cross during dispersal and migrations, they face different threats throughout their life cycle.

 

When they are young, sea turtles are an important diet source for many species, like ghost crabs, sea birds, and large fish, including sharks. However, these natural predators are usually in balance with the sea turtles, so that they will not cause their extinction. Humans are the only species posing a serious risk for the future survival of sea turtles.

Main threats to marine turtles

  • By-catch in fisheries 

  • Illegal consumption and trade in eggs, meat and carapaces

  • Nesting habitat degradation due to coastal development and coastal erosion

  • Global warming leading to feminised populations and embryo mortality 

  • Sea-level-rise causing embryo mass mortality

  • Plastic and other marine debris

  • Ocean pollution

By-catch in fisheries 

In the sea, hundreds of thousands of turtles are annually by-catch in fishing nets and hooks that were meant to catch other organisms, but eventually capture many turtles, as well as dolphins, whales, and seabirds. In addition, they are also very threatened by pollution, especially plastic, as they confuse plastics (e.g. plastic bags, fibers, and straws) with food, ingesting it and often suffocating to death.

Illegal consumption and trade in eggs, meat and carapaces

Illegal capture of sea turtles both at sea and on nesting beaches, and illegal harvesting of their eggs is another major threat, especially when these activities are encouraged by illegal trade.

Nesting habitat degradation

On nesting beaches, coastal erosion, caused by sand extraction, destruction of coastal vegetation, coastal development and rising sea levels, destroys many sea turtle nests. Ultimately, erosion and the presence of infrastructures (e.g. hotels or seawalls) can wipe out all the sand on the beach.

Climate change

Climate change, particularly global warming, which results from the excess greenhouse gases that humans release into the atmosphere through industry and deforestation, contributes to the increased frequency of severe storms and to rising seas through thermal expansion and ice melting. Due to these phenomena, in some parts of the world almost all nests are flooded and damaged by salt water. On the other hand, rising incubation temperatures are causing mass mortality of developing embryos.

 

Global warming has another consequence, which is the feminisation of populations (i.e. only females being born). This can happen because sea turtles have temperature-dependent sex determination, which means that the incubation temperature of their eggs determines whether female or male turtles are born. If eggs incubate at cooler temperatures (usually below 29 °C) mostly males hatch, while at warmer temperatures (about 31 °C and higher) more females are produced. At intermediate incubation temperatures both sexes are born in similar proportions (ca. 29 - 30 ºC). With global warming, the sand on the beaches is getting too hot, such that some populations can only produce females! If in the future there are no males to reproduce, the population becomes extinct!

 

Without conservation actions these threats will lead to the decline of many sea turtle populations!