Glossary

Non-renewable resource = a natural resource that is not replaced as it is used, unlike renewable energy sources. The former include fossil fuels, such as oil, coal and gas, whose reserves will run out one day, and nuclear power. The use of such energy sources also raises atmospheric pollution concerns since the burning of fossil fuels releases large amounts of the gas carbon dioxide (causes global warming) and poisonous gases such as nitrogen dioxide and sulphur dioxide. The supplies of oil are predicted to run out in less than 50 years – fossil fuels form over millions of years from the remains of dead plants and animals.

Thermohaline circulation = the movement of water throughout the ocean based on the water's density. Water density is determined by temperature and salinity (the amount of salt dissolved in the water). The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyer, the global conveyor belt. The ocean is divided into a number of different layers, much like the layers in a cake. Cold water is denser/heavier than warm water and this sinks down to the depths of the ocean in areas close to the poles, taking oxygen with it from the atmosphere. At the tropics (close to the equator), this cold water heats up and rises to the surface, only to re-sink at the poles, circulating oxygen and heat around the world and thus controlling our climate.

Filter-feeding animals = Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. Filter feeding is one of the four major types of feeding. Some animals that use this method of feeding are clams, krill, flamingos, sponges and whale sharks.

Particulates = Solid particles suspended in a gas or liquid. Such particles usually have a small diameter (are very fine) and remain suspended in the water for a long time, before settling on the bottom or on other surfaces, turning the water milky white and cutting off sunlight to photosynthesizing organisms. Particulates are also a common source of atmospheric pollution.

Extinction = is the cessation of existence of a species or group of taxa, reducing biodiversity. The moment of extinction is generally considered to be the death of the last individual of that species. Because a species' potential range may be very large (e.g. many bird species are found dispersed over more than one continent), determining the exact moment of extinction is difficult. This difficulty leads to phenomena such as Lazarus taxa (after Lazarus in the Bible), where a species presumed extinct abruptly "re-appears". Extinction is a natural process which is being speeded up by man and his activities. A typical species becomes extinct within 10 million years of its first appearance,[2] although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Sometimes, mass extinction events occur, with large numbers of species going extinct over a short period of time (e.g. the dinosaurs, ca. 60 million years ago).

Bycatch = Fishes or other animals caught by accident in fishing gear; species that the fishers don't want to catch. Bycatch is usually thrown back dead or dying. Bycatch is also called "bykill" or "wasted catch." One example of by-catch is dolphins caught in tuna nets. As dolphins are mammals and do not have gills they may drown while stuck in nets underwater. This by-catch issue has been one of the reasons of the growing ecolabelling industry, where fish producers mark their packagings with something like "Dolphin Friendly" to reassure buyers. Concerns about bycatch have led fishermen and scientists to develop devices they can put on their nets to reduce unwanted catch. The "bycatch reduction device" (BRD) and the Nordmore grate are net modifications that help fish escape from shrimp nets. All U.S. shrimp trawlers—and all foreign fleets selling shrimp in the U.S—are supposed to outfit their nets with trap-door "Turtle excluder device," or TEDs, to let sea turtles escape.