Arxiu d'etiquetes: ocean acidification

Why do we need ocean?

Fortunately, society is more concerned about the state of conservation of the environment due to human activities, both on land and at sea. In case there are still who think we do not need sea at all, this article aims to show what benefits gives us the sea.

WHICH ISSUES ARE AFFECTING THE SEA?

Did you know that some studies suggest that the entire surface of the seas and oceans of the Earth is hit by some human activity? In fact, 41% of the surface is affected by more than a factor of anthropogenic origin.

According to the United Nations Environment Programme (UNEP), there are several anthropic impacts at sea:

  • Ocean acidification.
  • Coral bleaching [More information here].
  • Chemical contamination.
  • Global change [You can read about the effects of global change on plants, whales, corals, reptiles and the current sea level rise].
  • Increase in toxic algae.
  • Increased invasive species [Discover what is an invasive species!].
  • Increase of jellyfish [If you want to know how are jellyfish and want to learn to identify the species of the Mediterranean, visit this article].
  • Loss of biodiversity.
  • Loss of habitats.
  • Nutrient overload.
  • Overexploitation of species with commercial interests.
  • Dead zones.

problemas mar contaminación
There are many anthropic impacts at sea, like pollution by several types of products and materials (Picture: NOAA, Creative Commons).

Not only do they affect marine ecosystems, but also affects the human population because the ecosystem services promote our welfare. So we can ask: why do we need the sea?

WHICH BENEFITS DO WE OBTAIN FROM SEA?

According to TEEB, ecosystem services are all those direct and indirect ecosystem and biodiversity contributions to human welfare. These services are: supply services, cultural services and regulation services.

SUPPLY SERVICES

All those contributions of ecosystems that take place directly or indirectly to human welfare, whether they have a biological or geological origin, are part of supply services.

Foods that the sea provides is one of the most important supply services to humans, including fish, shellfish and algae. An example of this is the fact that supplies 20% of the animal protein intake to 3,000 million people and that more than 120 million tons of fish were consumed in 2010. For all this, the current situation of exploited populations is critical in many cases, as you can read in this article.

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Sea supplies 20% of the animal protein intake to 3,000 million people  (Picture: Pixabay).

Sea is also a source of renewable energy because it is the source of many weather events (like wind) and tides and currents. Thus, sea provides wind energy and tidal power (generated by tides, currents and waves).

Another benefit that we get is different biotic or geologic materials, such as salts, ornamental materials and mineral resources. Without going into the details of the high environmental impact of extracting marine mineral resources, materials such as sand, diamonds, metals such as gold and tin, coal, gas hydrates, oil, gas and some others are exploited [can read more in this document of the International seabed Authority (ISA)].

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The exploitation of marine geologic resources, which is not free of impacts, lets obtain many diverse resources (Picture: National Geographic).

In addition, we benefit from certain substances and organisms that have some beneficial property to humans, such as medicines and cosmetics.

CULTURAL SERVICES

Cultural services are those that are obtained through direct experience with ecosystems. Although they are not the most important, we must also taken into consideration.

Ecosystems help to the creation and maintenance of cultural identity and sense of belonging to a community. What would we be without our festivities and without the different types of food?

Marine ecosystems enable developing advocacy and awareness by sea. They also contribute to the increase of scientific knowledge through research of different types. If you’re a biologist, would you like to discover a new species?

ctd
Research in marine environment let obtain useful knowledge for society (Picture: Perplex Me Not).

It is also the basis for many recreational activities such as whale watching, diving, tourism, recreational fishing and navigation activities [Do you want to know if recreational fishing is compatible in marine reserves?].

Here we could talk about more services, but I focused on the most relevant.

REGULATION SERVICES

Last but not least, marine ecosystems are responsible for the proper functioning of ecosystems as a whole. They are the most important services because from them depend all the rest.

In marine ecosystems, it occurs a set of processes by which they maintain or improve water and sediment quality. To give an example, they are involved in the oxygenation of dead zones and to absorb waste or pollutants.

But, certainly, it is important to highlight its key role in regulating the Earth’s climate. Earth’s oceans are the largest sink for greenhouse gases because they capture  carbon dioxide away from the air and distributes it in depth. So, they help to fight against global change, but everything has its limit.

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Due to the power of oceans in absorbing dioxide carbon, they play a key role in climate regulation  (Picture: El Confidencial).

On countless occasions, we have seen beaches to disappear after a storm, a hurricane and other extreme events. Do you want to know the reason? The main reason is that due to human action, our coast has lost its protective function, ie, has lost the ability to buffer natural disturbances. In a healthy beach, after a storm, it would regenerate naturally. Well, when a beach disappears, then  we have problems in promenades or houses built  at first line of the coast.

Although we could explain some more benefits, I will finish by mentioning its importance in providing the necessary nutrients for marine organisms and habitat maintenance of biodiversity.

REFERENCES

  • FAO. (2012). The State of World Fisheries and Aquaculture. FAO. Rome.
  • Fernando Santos-Martín, Carlos Montes, Paloma Alcorlo, Susana García-Tiscar, Blanca González, María Rosario Vidal-Abarca, María Luisa Suárez, Laura Royo, Inmaculada Férriz, Juan Barragán, Juan Adolfo Chica, César López y Javier Benayas. 2015. La aproximación de los servicios de los ecosistemas aplicada a la gestión pesquera. Fondo Europeo de Pesca, Fundación Biodiversidad del Ministerio de Medio Agricultura, Alimentación y Medio Ambiente. Madrid.
  • Jackson, J.B., Kirby, M.X., Berger, W.H., Bjorndal, K.A., Botsford, L.W., Bourque, B.J., Bradbury, R.H., Cooke, R., Erlandson, J., Estes, J.A., et al. (2001). Historical overfishing and the recent collapse of coastal ecosystems. Science 293, 629–637.
  • MA (Millennium Ecosystem Assessment). (2005). Ecosystem and Human Well-being. Island Press. Washington.
  • Notes of the subject “Geología de los océanos” of the Master in Oceanography and Marine Environment Management (UB).
  • TEEB. (2012). The Economics of Ecosystems and Biodiversity in Business and Enterprise. Joshua Bishop (ed.). Earthscan, London and New York. Urquhart, J., Acott, T., Reed, M., Courtney, P. (2011). Setting an agenda for social science research in fisheries policy in Northern Europe. Fish. Res. 108,
    240–247.
  • UNEP. (2006). Marine and coastal ecosystem and human well-being. A synthesis report based on the finding of the Millennium Ecosystem Assesment. UNEP.
  • Main picture: Stilts fishhermen Sri Lanka (Bernard Gagnon, Creative Commons).

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Why are sea turtles threatened?

Last week, we saw with detail how is the life of a sea turtle. Did you miss it? So, click here to read it! This week, I am still talking about his amazing animals, but I am focusing on the dangers that are threatening them, both natural or anthropic, and which actions we can do to save them. 

NATURAL THREATS 

Sea turtles are threaten by natural and anthropic dangers. Natural threats include egg loss due to the inundation or erosion of the beach, predation at all life stages, extreme temperatures and disease.

Egg loss

High tides and storms can produce the egg loss for several reasons: the drowning of the eggs, the beach erosion or accretion or nests are washed away. Moreover, there are some animals that feed on sea turtle eggs.

seaturtleeggs
There are several reasons that explain the egg loss (Picture: PaddleAndPath).

Predation on turtles

Despite little turtles usually leave the nest at night, the risk of being eaten by a predator is not zero, since they are part of the diet of raccoons, birds, crabs, sharks and other fishes. Young and adult turtles are also feed by some animals, like sharks and other big fishes, but the impact is not as big as in the first stages. Read the post of the last week if you want to know how many turtles die of old age for each 10.000 eggs. The number will shock you!

Els crancs poden menjar-se les tortugues acabades de sortir de l'ou (Foto: Gnaraloo Turtle Conservation Program, Creative Commons).
Crabs eat the hatching turtles (Picture: Gnaraloo Turtle Conservation Program, Creative Commons).

Hypothermia

Below 8º to 10ºC, turtles become lethargic and buoyant until they float at the surface (this condition is known as cold-stunning). At temperatures below 5º to 6ºC death rate can be important.

Diseases

Parasitic infections are common in sea turtles. Up to 30% of the loggerhead sea turtles in the Atlantic ocean have trematodes that infect their cardiovascular system. These infections, at the same time, reduce their immunological defences and then may be infected by bacteria (like Salmonella or E. coli).  Dinoflagellate blooms are also a threat for them because of the poisonous content produce health problems.

ANTHROPIC THREATS

Four are the main anthropic threats for marine turtles: egg and turtle poaching, destruction of nesting beaches, pollution and fisheries by-catch. Here, we will see some more.

Poaching

Fortunately, poaching is not present all over the world, but it can be specially important in some countries. Turtles are hunted for their meat and cartilage or for their shells (used in jewellery and like a decoration). Egg collection is also present.

Tortugues marines comissades per la policia de les Filipines (Foto: Mongabay).
Sea turtles confiscated by Philippine Police (Picture: Mongabay).

Venta d'ous de tortuga marina (Foto: OceanCare).
Sale of sea turtle eggs (Picture: OceanCare).

Destruction of nesting beaches

The building of infrastructures to protect ocean front property produce that females cannot access to nesting beaches and, moreover, produce their erosion. Beach nourishment to fight against beach erosion also affect them because the new beach buries the nests, offshore dredging kills them, beaches may become too compacted for nesting and steep and sand can have different properties (what may reduce, for example, gas diffusion). Tourism also affect them.

Pollution and garbage

It is not completely known if the pollutants, such as fertilizers and pesticides, have a direct impact on sea turtles, but among indirect effects there are the habitat degradation, considering that excess nutrients increase harmful algal blooms.

Garbage is also a problem. Turtles with plastic in the stomach have been found because they confuse plastic bags with jellyfishes, what block intestines and produce their death. Not only are plastics ingested, but also do they become entangled in debris like nets, fishing line or other plastic items. This produces a growth deformation.

La ingesta de plàstics (Foto: Fethiyetimes).
The ingestion of plastic blocks their intestines and produce death (Picture: Fethiyetimes).

Fishing by-catch

Sea turtles are also threaten by fishing by-catch.

Drift fishing, although is forbidden in Spain, are still used and every year, each boat produce the death of a hundred animals.

The longline fishing has an important impact. In Spanish waters, every year, are captured between 15,000 and 20,000 individuals. Despite they return alive to the ocean, they have a hook in the mouth and produce post release death for the wounds. Here you can read a review of the methods to reduce by-catch on loggerhead sea turtle in longline fishing. 

La pesca de palangre captura entre 15.000 i 20.000 exemplars cada any en aigües espanyoles (Foto: Phys).
Longline fishing captures between 15,000 and 20,000 individuals in Spanish waters each year (Picture: Phys).

Mortality in trawling depends on trawl times: mortality increased from 0% with times less than 50 minutes to 70% after 90 minutes. This is explained by the breathing capacity of the animals.

Global change

Ocean acidification due to the continued release of carbon dioxide may have an important impact on sea turtle populations because the quality of the food will probably reduce.  The sea level rise will have a negative impact on sea turtles because endanger the existence of beaches. Moreover, the increase in the temperatures will affect the growth and the sex ratio, since sex depends on the temperature in reptiles: below 29ºC prevail males and above, females.

HOW CAN WE HELP THEM?

  • Avoid any activity or behaviour that can annoy sea turtles. In the case of feeling annoyed, you will observe that they try to leave the area, they do a fast diving and they do abrupt swimming movements.
  • Reduce the speed of the ship if you see any element that could be a sea turtle. In the case of being a turtle, avoid any manoeuvre that can endanger them.
  • Pick up fishing gear or garbage present in the water.
  • In the case of the animal being in danger, first, call the emergency phone of your country. In the case of Spain, call 112. However, there are some actions that you can do while vets arrive:
    • Turtle with a broken shell or open injuries: cover the injuries with a wet rag with iodine (never in the eyes, ears and nose).
    • Drowned turtle: maintain the animal for 5 minutes with the ventral part face up and with the body inclined (head downwards), moving its fins.
    • Turtle with plastics in the mouth: remove the plastic taking care and call the emergency number.
    • Dead turtle: don’t touch the animal and call emergencies.
    • Hooked turtle: don’t stretch the hook and cut the line with 30 cm.
  • Inform the proper authority of the location of possible nests. Some clues:
    • Tracks of turtles in the sand of the beach, with a shape of a V, with the nest in the vertex.
    • Depression in the sand, what indicates about the eclosion of eggs.
    • Observation of a turtle doing the lay.
    • Remainder of eggs or hatching animals.

REFERENCES 

  • Consejería de Medio Ambiente de la Junta de Andalucía (2014). Varamientos de Especies Marinas Amenazadas. Guías prácticas voluntariado ambiental.
  • Gray, J (1997). Marine biodiversity: patterns, threats and conservation needs. Biodiversity and Conservation 6, 153-175
  • Hamann, M et al. ‘Climate Change And Marine Turtles’. The Biology Of Sea Turtles. Volume III. Jeanette Wyneken, Kenneth J. Lohmann and John A. Musick. 1st ed. New York: CRC Press, 2013. 353-378. Print.
  • Harrould-Kolieb, E. & Savitz, J. (2009). Acidificación: ¿Cómo afecta el CO2 a los océanos? Oceana
  • Ministerio de Agricultura, Alimentación y Medio Ambiente. Guía de buenas prácticas en las Zonas Especiales de Conservación de ámbito marino de Canarias. España. http://www.magrama.gob.es/es/costas/temas/proteccion-medio-marino/201311_guia_bbpp_web_tcm7-229984.pdf
  • Oceana (2006). Las tortugas marinas en el Mediterráneo. Amenazas y soluciones para la supervivencia. 38 pp.
  • Otero, M., Garrabou, J., Vargas, M. 2013. Mediterranean Marine Protected Areas and climate change: A guide to regional monitoring and adaptation opportunities. Malaga, Spain: IUCN. 52 pages.
  • Shigenaka, G (2010). Oil and Sea Turtles. Biology, planning and response. NOAA
  • Smith, T & Smith R (2007). Ecología. Pearson Educación (6 ed.)
  • Velegrakis, A., Hasiotis, T., Monioudi, I., Manoutsoglou, E., Psarros, F., Andreadis, O. and Tziourrou, P., (2013). Evaluation of climate change impacts on the sea-turtle nesting beaches of the National Marine Park of Zakynthos Protected Area. Med-PAN North Project, Final report, 81 pp.

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