Formación diaria en las ocho inteligencias

Marine biodiversity refers to the variety of life forms in the sea at all levels of biological organisation including plants, animals and microorganisms, the genes that they contain and the ecosystems that they form. 76 _{In its simplest form,}

marine biodiversity is sometimes described as being composed of genetic diversity, species diversity and ecosystem diversity. These categories characterise how biodiversity encompasses a number of different levels, ranging from the gene to the ecosystem.77

The nature of marine biodiversity is that it is changing over periods of years to centuries due to ecological succession. A major ecological succession sequence might begin with a disturbance, such as a lava flow or whale fall,78 _{which can}

create new habitats, or a storm which might remove habitat-creating dominants.79 _{Natural changes that occur in the absence of human impacts}

provide an insight into biodiversity trends caused by human drivers.80

There are a number of events that contribute to the decline in marine biodiversity other than natural succession. These include extinctions, invasions and hybridisations, the reduction in species populations, diminished or removed habitats, and the disruption of ecosystem processes such as the availability of nutrients and cycling of water.Before the oceans were exploited by humans, naturally occurring environmental disturbances, such as those mentioned above, were the only disturbances ‘resetting the successional clock’. However, human

76 _{Enric Sala, Nancy Knowlton, ‘Global marine biodiversity trends’ (2006) 31 Annual Review of Environmental}

Resources 98.

77 _{Marine Biodiversity Decline Working group, ‘A National Approach to Addressing Marine Biodiversity}

Decline’ Report to the Natural Resource Management Ministerial Council (Australia) April 2008, 7.

78 _{A whale fall is the term used for a whale carcass that has fallen to the ocean floor. When a carcass falls}

into deep water there are few scavenger species and subsequently the carcass may provide sustenance for a complex localised ecosystem over periods of decades.

79 _{C R Smith, H Kukert, R A Wheatcroft, P A Jumars, J W Deming, ‘Vent fauna on whale remains’ (1989)}

341 Nature 27–8.

29 activities and interference are now the strongest drivers of change in marine

biodiversity at all levels.81

Marine pollution

Marine pollution is an important contributor to the loss of marine biodiversity and changes to marine ecosystems. Apart from pollution as a result of global warming (such as the increase in the uptake of carbon dioxide resulting in acidification), the major sources of marine pollution come from agricultural run- off, land-based chemical pollution, and ocean debris, particularly plastics. One side effect of increased nutrients in coastal waters is eutrophication, which can trigger anoxic events resulting in hypoxia or dead zones. These dead zones have been particularly prevalent in the Gulf of Mexico due to high levels of nutrients in farm run-off.82 _{(Dead zones are discussed in greater detail in Chapter Three.)}

Very few life forms can survive in these toxic, low-oxygen dead zones with the one exception being jellyfish. Jellyfish populations are believed to be on the increase and most analysed data sets show variations in jellyfish population size associated with climatic regime shifts at decadal scales.83 _{It is believed the causes}

of unusually high numbers of jellyfish blooms may be related to eutrophication, over-fishing and climate change.84 _{Jellyfish are also causing obstructions such as}

clogging the water intakes on ships, mining operations, power stations and desalination plants, as well as damaging engines around the world.85

Summary

A reduction of emissions is required to address climate change, and the nature of the oceans as a carbon sink has sparked a number of different geoengineering proposals to reduce excess atmospheric CO2. While carbon capture and storage

81 _{Sala, above n 76, 100.}

82 _{Gulf’s Dead Zone Worse in Recent Decades, Science 8 April 2005 308: 195 [DOI:}

10.1126/science.308.5719.195d] (in Random Samples).

83 _{Jennifer E Purcell, ‘Anthropogenic causes of jellyfish blooms and their direct consequences for humans: a}

review’ (2007) 350 Marine Ecology Progress Series 153.

84 _{Purcell, above n 83, 153–74.}

85 _{Purcell, above n 83,155; See also: Brian Williams, ‘Jellyfish taking over the seas’ The Courier mail, 18 June}

can be land or ocean based, other proposals such as ocean fertilisation or storing CO2 in the water column or as lakes on the ocean floor are not. The marine

environment is sensitive and it is important that the biodiversity of oceans is protected before any geoengineering proposal for increasing the capacity of the oceans to hold CO2 is undertaken.

The next chapter examines ocean fertilisation including the possible environmental damage arising from the activity.

31

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Introduction

Ocean fertilisation is a method of geoengineering proposed by some as a quick, cheap and effective solution to the world’s CO2 emissions problems. The oceans

can draw down around 30 per cent of atmospheric CO286 through the biological

and solubility pumps (Chapter One). Ocean fertilisation uses iron or other nutrients to further stimulate phytoplankton growth in barren areas of the ocean. Some believe this will increase the draw down of CO2 and consequently cool the

globe.87

The rate the ocean can physically remove the CO₂ from the atmosphere is regulated by the thermohaline circulation. Constraints imposed by the limited rate of ocean circulation mean that even though the ocean represents an enormous natural reservoir for carbon in the global carbon equation, estimates of the actual oceanic uptake of CO2 suggest that only around one-third of CO2

emissions can be taken up.88 _{The sinking of cold, salty waters in the Polar}

Regions drives the thermohaline circulation. As the solubility of gas increases at lower temperatures, cold water takes up more CO2, which sinks to the deep

ocean until resurfacing many hundreds of years later.89 _{It is believed that in pre-}

industrial times the global carbon cycle was in equilibrium, with terrestrial and oceanic systems contributing equally to both emissions and uptake of CO2. Since

industrialisation, however, the system is no longer in equilibrium and atmospheric CO2 is increasing at a rate of over four GtC per year.90

86 _{Solomon, above n 1.}

87 _{G R Biggs, T D Jickells, P S Liss, T J Osborn, ‘The role of the ocean in climate’ (2003) 23 International}

Journal of Climatology 1127–59.

88 _{L S Jorge, B Michael ‘Carbon biogeochemistry and climate change’ (1994) 39 Photosynthesis Research 209–34.} 89 _Ibid.

90 _{J Adhiya, S Chisholm, ‘Is ocean fertilization a good carbon sequestration option?’ (2001) Massachusetts}

THE HISTORY OF OCEAN FERTILISATION