Introduction
Cruise liners have in recent times become one of the most important modes of transport. It has been considered one of the safest modes of transport not only in the United States but also in the whole world. Cruise liners often docks at a port carrying a large number of passengers. It has become an important tourist activity with those on board spending days exploring marine life. Its capacity to contain many passengers at a time makes it an ideal mode of tourism for a large group of persons and the fact that everybody is contained in one ship helps in bonding the travellers.
The industry has grown rapidly in the world, recording a growth rate of 8 percent between 1992 and 2002. By 2001, cruise ships’ fleets had risen to about 167 vessels. This means at one docking time, large number of vessels is expected to be at a port in one time. This calls for a well maintained port to handle this growing number of cruise ships. They also have adverse effects in the marine environment if not well handled. (Barrow, 1997)
Environmental impacts of cruise liners
As we have seen, cruise liners have increased the number of vessels per fleet. According to GAO (2000), the number of vessels and the number of passengers docking at a port at one time definitely may have a strain on the marine environment. They generate a lot of waste which pollutes the marine environment. It has been studied that some cruise vessels have an equivalent of small cities in terms of waste production emission. Here are some of the ways in which cruise liners cause environmental pollution.
Sewage
This mainly comes from vessel sewage and other water waste like from medical facilities. It has been estimated that in a cruise ship there is about five to ten gallon of sewage per person per day. It is to be understood that due to the limited fresh water availability in the sea during sea fare sewage from cruise ships is usually more concentrated. It is less diluted due to water shortage in the long journey in the sea. Perhaps this sewage discharge has the most compounding effects of the marine life and also to the human being. It can harbour bacteria and viruses which can cause disease to marine life and also to human beings who consume marine products. It makes the water unsafe for swimming, diving and boating.
Sewage contains a lot of nutrients which encourage growth of plants in the water. This is specifically in the growth of algae in the process of eutrophication. Growth of algae in the marine environment leads to competition of oxygen between the marine animals and the growing algae. Growth of algae in mass leads to depletion of oxygen which can lead to death of marine life depending on oxygen for survival like fish and other animals in the marine environment.
This has been one of the factors leading to extinction of some animal species in marine life in some parts of the world. Inhabitation of marine environment by algae poses a danger to the existence of marine animals. In addition cruise sewage is always treated with chemical as per Marine Sanitation Devices. Chemicals like Chlorine, ammonia, and others used in the sanitation can pose a great threat to the marine life. Chemicals like ammonia can cause detoxification and consequently death of marine animals.
According to Michael and Davis (2002), in the United States, sewage from marine vessels is not subjected to the National Pollutant Discharge Elimination System (NPDES). However vessels are required to have a U.S. Coast Guard Certified MSD. This is a device which treats or store sewage before it is discharged to the environment. It must contain the sewage till it is disposed off. This is enforces under section 312 which requires all vessels to use the MSD device within a perimeter of 3 miles of the shore.
Also all vessels which are above 65 feets are required to install type II MSD device which meets a water quality standards of 200 coli form per 100 millilitres of water, and a type III MSD device which holds the sewage till its time of disposal. All the water discharge in the marine water must undergo the type I and type II MSD standards as stipulated under the US Clean Water Act.
Grey water
This is mainly water from sinks, showers, laundry, and others. Like the sewage, it also contains contaminants which lead to marine water pollution. It has pollutants like suspended oils, grease, soap, detergents, cleaners, pesticides, dental wastes and others. It may also contain toxicants like ammonia, nitrogen, phosphates, copper, mercury, nickel, silver and zinc. It is estimated that a cruise ship produces about 1,000,000 gallons of gray water in one week.
As we have seen, gray water contains a lot of toxicants that can lead to death of marine life and which have potential harm to human beings as well. Some toxicant like mercury and lead are non biodegradable and continue to persist in the food chain. They are poisonous toxicants that can cause death not only to marine animals but also to human beings. Mercury and lead when consumed by fish passes on to human being who in turn consume the fish.
It is however saddening to learn that there are no laid down rules prohibiting the discharge of gray water in the states or in US waters. In Alaska’s Great Lakes and state waters, discharger of gray water is prohibited. (ADEC, 2004)
Bilge water
It is estimated that a cruise ship will generate 25,000 gallons of this water in one week. This consists of fuel, oil and wastewater that come from engines and machineries. Together with fresh waste and sea water, it collects at the bottom of the ship’s hull which can be due spills, leaks and in line with other operations in the ship. It may also come from rags, cleaning agents, paint and metal shavings. This is perhaps the leading environment polluter of the marine environment. In many instances oils spills have caused massive damages to the marine life and the environment in general. Spilt oils cover the water surfaces which deny the entry of light and oxygen to marine life. This leads to death of marine animals from suffocation. The marine environment is an ecosystem of interdependent plants and animals.
Coverage of water surface denies light to the growing marine plants which needs light to manufacture foods and in turns decreases the level of emission of oxygen by these plants. Instances of spilt oils have called for international cooperation between affected countries in trying to tackle the problem. This is due to the effects it has on the marine life and the coastal beaches. It makes the water unsafe for marine activities like swimming, boating and others.
Due to the serious effects it posses to the marine environment, discharge of bilge water is regulated und the Oil Pollution Act in Section 311 of the Clean Water Act. Vessels are not allowed to release any discharges which have an oil content of more than 15 ppm (parts of oil per one million parts of waters) within a radius of 100 miles of the shore. Beyond this radius, release containing more than 100 ppm is prohibited. The rule is more stringent in cruise liners which are required to treat the bilge water discharge to 5 ppm.
As we have said before, bilge water posses more danger to the marine life not only in one country but to the whole sea. This problem has attracted international concern and it is addressed in the International Convention for the Prevention of Pollution from Ships
Ballast water
In its journey, ships take in millions of gallons of water in order to stabilize the vessel. This is called ballast water. The vessel takes in water at one location and in effect discharges it in another location. It is to be understood that the vessel takes in with the water various species including larvae, fish eggs and other organisms and consequently discharges them in another location. This has led to the introduction of new species in marine environment where they previously never existed and consequently the displacement of certain marine species in one location. The introduction of new species in an environment obviously disrupts the marine ecosystem.
The Ballast Water Management for Control of Non-indigenous Species Act requires that vessels must exchange the ballast water within 200 nautical miles from land and 2000 meters deep. It also gives a provision of retaining the ballast water in the ship. This act is currently enforced in California waters.
Solid waste and hazardous materials
Cruise liners generate a lot of solid wastes like food wastes, cans, glass, paper, and others. These can have an effect of causing entanglement of the marine animals. Hazardous materials like by-products of dry cleaning, photo processing, fluorescent bulbs which contain mercury, and others. These wastes are toxic and carcinogenic and can be passed on through the food chain.
The Marine Plastic Pollution and Control Act in the United States is the one which regulate the disposal of solid waste. It prohibits disposal of plastics in the marine water within 25 nautical miles and rules out disposal of paper, glass, rags, and others within 12 nautical miles from land. Like wise U.S. Resource Conservation and Recovery Act require cruise ships offload all the hazardous materials water to the land for treatment and disposal.
Conclusion
It has been good noting that there have been initiatives from the cruise industry to save the environment. The International Council of Cruise Lines (ICCL) constitutes the world’s largest cruise lines and helps to regulate environmental pollution. Between 1992 and 2001, it reported 50% reduction in marine pollution by cruise ships. In 2001 it adopted the Cruise Industry Waste Management Practices and Procedures, a document that outlined ways to reduce marine pollution by cruise ships. Many cruise ships have adopted voluntary measures to reduce pollution. This has enhanced good practices in the cruise industry in an effort to manage and sustain the marine environment.
References
Alaska Department of Environmental Conservation (ADEC) (2004): Assessment of Cruise Ship and Ferry Wastewater Impacts in Alaska. ADEC 2004 report.
Barrow, C. (1997). Environmental and social impact assessment; Arnold, London.
GAO (2000): Marine Pollution: Progress Made to Reduce Marine Pollution by Cruise Ships, but Important Issues Remain. Report to Congressional Requesters.
Michael, F. & Davis, J. (2002): Cruise Control. A report by the Ocean Conservancy.