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.

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.

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)].

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?

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.

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).

Oil spill effects on marine environment

Oh the occasion of the accident of the Russian fishing boat called Oleg Naydenov close to Grand Canary (Spain), the article of this week is about the effects of petroleum on marine environment. Here, I am going to talk about the origin of the petroleum in the sea, which are the transformations that suffer and the effects on marine fauna and flora. 

INTRODUCTION

The accident of the Russian fishing boat called Oleg Naydenov off of Grand Canary, which has finished with its sinking, is causing the appearance of oil in an area of 12 square km. The reason is that it sank with more than 1,400 tonnes of oil, 30 of diesel oil and 65 more of lubricant.

ORIGIN OF HYDROCARBONS IN THE SEA

Despite oil tanker accidents have a huge impact in the media, they represent a small portion of the amount of hydrocarbons that get in the sea. In general terms, these are the main sources of petroleum in the sea:

• Industrial discharges and urban dredging: 37%.
• Boat’s operations: 33%.
• Oil tanker accidents: 12%.
• Atmosphere: 9%.
• Natural sources: 7%.
• Exploration and production of hydrocarbons: 2%.

Although this values can vary depending of the sources, in general they represent quite good the proportions. It has been estimated that, each year, are poured into the sea 3,800 millions of litres of hydrocarbon, equivalent to 1,500 Olympic pools.

HYDROCARBON TRANSFORMATIONS IN THE SEA

When hydrocarbons are spilled into the sea (accidentally or deliberately), their features and shape change. This changes are physical, chemical and biological. This are the mechanisms:

1. Evaporation: it allows that certain substances of the hydrocarbons go to the atmosphere, reducing about 40% its volume just in the first day. In any case, the surrounding atmosphere will be flammable.
2. Dispersion: it consists on the fragmentation of the oil patch into small drops. When these drops are small enough, they remain in suspension and they mix with water and favours the biodegradation and sedimentation.

   

   Oil dispersion is positive because it allows the biodegradation (Picture from Ecosfera)

3. Emulsification: consists on the absorption of water so the hydrocarbon’s volume increases between 3 and 4 times. This hampers the oxidation and biodegradation.
4. Solution: depending on the product’s composition, the water temperature and its agitation. Only the more volatile components can be dissolved.
5. Oxidation: the effect of the oxidation can produce a compound that is easier or more difficult to degrade.
6. Sedimentation: consists on the down vertical displacement of the hydrocarbon’s particles. Depending on its density (with respect to water), the size and the agitation of the sea.
7. Biodegradation: consists on the elimination of hydrocarbons by living beings, like bacteria and fungus.

PETROLEUM’S EFFECTS ON MARINE ENVIRONMENT

As we have said in the beginning of the post, the main goal of this is to comment which are the effects of petroleum (and other hydrocarbons) on marine fauna and flora. Let’s start!

The effects of petroleum on fauna are wide due to the high diversity of marine organisms. The main effects on the marine biodiversity are:

1. Direct contamination: petroleum sticks on feathers, fur and scales, what make difficult the thermal isolation, movements and other important functions. As a consequence, this kills fishes, marine mammals and birds.

   

   Marine mammals are effected by petroleum pollution (Picture from Channel Island)

2. Modification of gas exchange: the petroleum sheet reduces the content of oxygen in the water, what produce the dead of the plankton and fishes, what produce the dead of the organisms that feed on them.
3. Alteration of seafloor: when petroleum is placed over the seafloor kills and produce sublethal effects on benthonic flora and fauna.
4. Intoxication: petroleum poisons marine fauna, soaking into its digestive system and its skin and mucosa. The result is, on the one hand, the dead for suffocation and genetic disruptions on fishes, molluscs, marine mammals, reptiles and birds; and, on the other hand, the intoxification of other organisms like humans when they feed on them.

   

   Only a quarter part of the contaminated marine birds achieve the earth, the rest dead (Photo: Marine Photobank, Creative Commons).

5. Increase of the infections: because petroleum produces a reduction of the resistance to infections. This is specially important in birds because when they clean the feathers theirself, they swallow petroleum, so they present sublethal concentrations.
6. Negative effects on fertility, reproduction and propagation of fauna and flora.
7. Modification of the behaviour.
8. Destruction of food sources.
9. Incorporation of cancerous substances on food webs. 
10. Effects on the availability of light: we cannot forget that the petroleum patch in the sea surface produce an important reduction of light in the water column. This causes a reduction or elimination of photosynthesis, essential process for the maintenance of food webs because the algae growth depends on light, which is consumed by herbivorous (and so on) and produce an oxygen input into the water. Moreover, we have to take in consideration that algae communities are shelter for many larvae and youthful fishes.
11. Marine communities alteration: at community level, there is a gradient of vulnerability of oil spills. From less to more vulnerability, the communities are: exposed cliffs, exposed rock platforms, fine sand beaches, middle to big sand beaches, exposed tidal planes, big sand beaches, gravel beaches, protected rocky beaches, protected tidal planes, marshlands and mangroves, subtidal seafloors of sand and gravel, mud subtidal seafloors, batial and abyssal seafloors, infralittoral and circalittoral seafloors and reef corals.

REFERENCES

• Notes of the subject Ecotoxicology and marine pollution of the Master in Oceanography and Marine Environment Management of the University of Barcelona.
• EmerCoast Coast. “Training on marine pollution risks. Environmental risks in the littoral and marine environments”.
• Course”Marine Pollution” from EuroInnova.
• Greenpeace (2012). Environmental impact of petroleum (Brochuere).