azwhales
Why the Ocean is so important?
Nowadays, we are faced with a number of threats for the marine environment, ranging from natural causes to anthropogenic causes and those come with their specific impact on the ecosystem. The marine environment supplies the planet with about 70% of the oxygen we need to survive, storages most of the carbon and detoxes waste. And furthermore, humans always loved these environments. There are cultural activities linked to the sea, like fishing, go for a swim or even just sitting quietly listening to the waves. We just love being around water, it puts us on a better mood. We can imagine that any threat to the services that these ecosystems provide can impact the wellbeing of mankind, potentially lead to the loss of income and good health, livelihoods and the lack of food security. Therefore, it is essential for us to understand the maximum about these impacts and what is the main reason (Worm et al., 2006; Liquete et al., 2013; Naeem et al., 2016).
What are the main threats?
According to W.J. Boonstra et al (2015), shared perceptions between marine scientists worldwide about the main threats to marine environments help shape and apply more pressure on the governments to create appropriate management plans. Therefore, it is important to be aware of global changes that deteriorate and influence the sustainability of marine environments.
Ocean’s main threats include a few natural processes like ocean acidification or global warming, which can directly affect some of the benefits that the ocean provides, such as carbon storage and waste detoxification. Additionally, there are several man-made menaces such as habitat loss for many species, overfishing or pollution among others. Based on surveys done to several marine scientists it was possible to construct a chart with the most concerning threats and respective impacts to marine environments worldwide (Fig.1) (Boonstra et al., 2015).
In this article, we will analyze some of the most pressing subjects, on which humans have a bigger or direct impact.
 |
|
Fig.1. Global threats and impacts in marine environments with a bottom-up approach (W.J. Boonstra et al., 2015).
|
- Climate change
Climate change will impose significant challenges to food security for both capture fisheries and aquaculture. Seafood currently provides 15% of the animal protein intake for the world’s population, along with essential nutrients and livelihoods (FAO, 2010; Cooley et al., 2012). At the same time, sea-level rise and potential increases in storm frequency and severity will threaten coastal communities. Unfortunately, both corals and temperate seagrasses are highly sensitive to warming and the occurrence of coral bleaching (Fig.2) from thermal stress may be augmented by ocean acidification (Doney et al., 2012; Hoegh-Guldberg et al., 2007).
 |
|
Fig.2. Coral bleaching caused by ocean acidification.
Range shifts in fish and shellfish populations attributed to climate have altered the magnitude and distribution of capture fisheries taken across the globe (Cheung et al., 2010).
Coastal habitats such as sea grasses, kelp forests, coral reefs, mangroves, wetlands, and dunes can provide protection from erosion and inundation due to storms. The shielding benefits of coastal habitats may become fewer in the future as the coastal human population expands (Irish et al., 2010) (Fig.3). Many of the coastal habitats also function as nurseries for recreationally and commercially important marine and estuarine species. Thus, fishing opportunities and coastal protection directly impact recreation and tourism, which are among the world’s most profitable industries (Brander et al., 2010). For example, on Australia’s Great Barrier Reef, surveys suggested that reef trips by divers and snorkelers could fall by up to 80% under reasonable scenarios of climate-induced coral and fish decline, resulting in loss of biodiversity and tourism as well (Kragt et al., 2009).
|
 |
|
Fig.3. Anthropogenic expansion to coastal areas.
|
- Overfishing
Fishing consists in harvesting the surplus of a fish population for the use of humans. With the effort of scientists and fishery management, fishing can be undertaken without harming the natural population. However, if too many individuals are fished, the population is considered to be harmed and/or overfished.
There are two types of overfishing (Gulland, 1983): growth overfishing and recruitment overfishing. The former occurs when fish are caught too young and therefore the individuals don’t achieve their full potential growth. Recruitment overfishing reduces the spawning stock, therefore the juvenile fish are not able to replenish the population. FAO states that most of the regions of the world’s oceans are presently producing less than 90% of their historical maximum. Of the main world fish stocks or species groups being monitored by the FAO, 3% are appeared to be underexploited, 20% moderately exploited, 52% fully exploited, 17% overfished, 7% depleted, and 1% recovering (FAO, 2009) (Fig.4).
 |
|
Fig.4. Overfishing. Nearly 80% of the world’s marine fish stocks are now fully exploited, overexploited or depleted.
|
- Marine plastic
In the marine environment there are substantial and constantly increasing quantities of plastic pollution, which is commonly referred as marine plastic. Only in 2010, an estimate of 4.8-12.7 million metric tons of plastic has gone to the world’s oceans from land-based sources (Jambeck et al, 2015).
Nowadays it is unquestionable the negative plastic impact on marine life. Charismatic marine organisms, including seabirds, turtles and cetaceans, hold a cultural and/or emotional importance to humans, and they are impacted by marine plastic through entanglement and ingestion among others. Plastic and its associated co-contaminants can cause sub-lethal effects such as reduced reproductive success or lack of feeding due to full stomach of plastic; and mortality (Fossi et al., 2014). Actually, almost every week appear on the worldwide mainstream media images and articles describing beached whales, dolphins and seabirds with stomachs full of plastic (Fig.5). And not only, but as well here in our tours, at a more local level, we can see dolphins, whales and turtles with plastic entangled, and a lot of plastic trash floating on the ocean (read our article about plastic pollution in the ocean).
 |
|
Fig.5. Dolphin’s fin entangled in plastic
|
In conclusion, we have to be aware of the threats to the marine environment in order to know, not only in which way they affect marine life, but also to those who depend on it to survive. In the present day, humans and our society will continue to have the biggest impact on these types of environments since our development is aggravating some of the threats and our actions increase the impact. The solution is on every one of us, just with simple things like recycling or even just not using plastic that often. We can be more of a benefit than a threat to our planet.
Article written by our marine biologists Laura González and Miguel Soares
REFERENCES
– Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, B. S., … & Sala, E. (2006). Impacts of biodiversity loss on ocean ecosystem services. Science, 314(5800), 787-790.
– Liquete, C., Piroddi, C., Drakou, E. G., Gurney, L., Katsanevakis, S., Charef, A. & Egoh, B. (2013). Current status and future prospects for the assessment of marine and coastal ecosystem services: a systematic review. PloS ONE, 8(7), e67737.
– Naeem, S., Chazdon, R., Duffy, J. E., Prager, C., & Worm, B. (2016). Biodiversity and human well-being: an essential link for sustainable development. Proceedings of the Royal Society B: Biological Sciences, 283(1844), 20162091.
– Boonstra, W. J., Ottosen, K. M., Ferreira, A. S. A., Richter, A., Rogers, L. A., Pedersen, M. W., … & Diekert, F. K. (2015). What are the major global threats and impacts in marine environments? Investigating the contours of a shared perception among marine scientists from the bottom-up. Marine Policy, 60, 197-201.
– FAO. Agriculture Organization of the United Nations. Fisheries Department. (2000). The State of World Fisheries and Aquaculture, 2000 (Vol. 3). Food & Agriculture Org.
– Cooley, S. R., Lucey, N., Kite‐Powell, H., & Doney, S. C. (2012). Nutrition and income from molluscs today imply vulnerability to ocean acidification tomorrow. Fish and Fisheries, 13(2), 182-215.
– Doney, S. C., Ruckelshaus, M., Emmett Duffy, J., Barry, J. P., Chan, F., English, C. A., … & Polovina, J. (2012). Climate change impacts on marine ecosystems. Annual Review of Marine Science, 4, 11-37.
– Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., … & Knowlton, N. (2007). Coral reefs under rapid climate change and ocean acidification. Science, 318(5857), 1737-1742.
– Cheung, W. W., Lam, V. W., Sarmiento, J. L., Kearney, K., Watson, R. E. G., Zeller, D., & Pauly, D. (2010). Large‐scale redistribution of maximum fisheries catch potential in the global ocean under climate change. Global Change Biology, 16(1), 24-35.
– Irish, J. L., Frey, A. E., Rosati, J. D., Olivera, F., Dunkin, L. M., Kaihatu, J. M., … & Edge, B. L. (2010). Potential implications of global warming and barrier island degradation on future hurricane inundation, property damages, and population impacted. Ocean & Coastal Management, 53(10), 645-657.
– Brander, K. (2010). Reconciling biodiversity conservation and marine capture fisheries production. Current Opinion in Environmental Sustainability, 2(5-6), 416-421.
– Kragt, M. E., Roebeling, P. C., & Ruijs, A. (2009). Effects of Great Barrier Reef degradation on recreational reef‐trip demand: a contingent behaviour approach. Australian Journal of Agricultural and Resource Economics, 53(2), 213-229.
– Gulland, J. A. (1983). Fish stock assessment: a manual of basic methods (Vol. 425). New York: Wiley.
– FAO. Agriculture Organization of the United Nations. (2009). General situation of world fish stocks United Nations Food and Agriculture Organization (FAO).
– Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., … & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768-771.
– Fossi, M. C., Coppola, D., Baini, M., Giannetti, M., Guerranti, C., Marsili, L., … & Clò, S. (2014). Large filter feeding marine organisms as indicators of microplastic in the pelagic environment: The case studies of the Mediterranean basking shark (Cetorhinus maximus) and fin whale (Balaenoptera physalus). Marine environmental research, 100, 17-24.
azwhales
Equipa de Biólogos da Futurismo
Sandrina Rodrigues
