Throughout human existence we have relied on the oceans – for food, as a waste dump, for recreation, for economic opportunities and so on. However, it’s not only our activities in the marine environment that affect life in the sea – it’s also the things we do on land.
With more than half the world’s population now living within 100 kilometres of the coast, it’s not surprising that our activities are taking their toll. Human impacts have increased along with our rapid population growth, substantial developments in technology and significant changes in land use. Over-fishing, pollution and introduced species are affecting life in the sea – and New Zealand is no exception!
Threats to marine habitats
Human actions at sea and on land are putting increasing pressure on the ocean and the species that live there.
Fisheries
Humans living near the coast have probably always used the ocean as a source of food. However, with advances in fishing equipment, larger ships and new tracking technologies, many fish stocks around the world have reduced significantly. Fish stocks on continental shelf areas are now widely considered to be fully or over exploited. Aside from reducing fish stocks, unsustainable fishing practices can have other negative impacts on the marine environment. For example, some fishing techniques such as dredging and trawling can cause widespread damage to marine habitats and organisms living on the sea floor. These techniques also often capture non-target species (known as bycatch) that are then discarded.
Rights: Ra Boe, CC BY-SA 2.5 Commercial fishing boat
Fishing was probably the first use of the oceans by humans. In the last century, significant increases in commercial fishing have resulted in the over-exploitation of many fish stocks.
In New Zealand, fisheries are managed by a quota system that sets catch limits for commercially important species and aims at sustainable management of our fish stocks. The Royal Forest and Bird Protection Society (NZ) publishes the Best Fish Guide to try and encourage us to make more sustainable choices when purchasing seafood. The list evaluates fish stocks and bycatch levels and the fishing methods used.
Pollution
Our oceans have long been used as an intentional dumping ground for all sorts of waste including sewage, industrial run-off and chemicals. In more recent times, policy changes in many countries have reflected the view that the ocean does not have an infinite capacity to absorb our waste. However, marine pollution remains a major problem and threatens life in the sea at all levels.
Rights: Jeff Schmaltz, MOD IS Land Rapid Response Team at NASA GSFC Phytoplankton bloom
This image shows a large phytoplankton bloom that occurred around New Zealand in October 2009. The image was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA’s Terra satellite.
Some marine pollution may be accidental, for example, oil spills caused by tanker accidents. Some may be indirect, when pollutants from our communities flow out to sea via stormwater drains and rivers. Some effects may not be immediately obvious, for example, bioaccumulation – the process where levels of toxic chemicals in organisms increase as they eat each other at each successive trophic level in the food web.
C. that there may be more than one way to interpret data
Explanation:
When determining if an explanation is correct you must always remember that there may be more than one way to interpret data. Depending on the context that the explanation is being used in or who is reading it, the explanation may be interpreted in two completely different manners which may be far off from the original intended explanation. This can therefore completely nullify or maybe even expand the original determination.
High temperatures and greater rainfall increase the rate of chemical weathering. 2. Rocks in tropical regions exposed to abundant rainfall and hot temperatures weather much faster than similar rocks residing in cold, dry regions. ... Soils affect the rate in which a rock weathers.
