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Marine biology is the scientific study of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.
Plankton are the diverse collection of organisms that live in large bodies of water and are unable to swim against a current. The individual organisms constituting plankton are called plankters. They provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales.
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems, and is often recognized by the discoloration in the water from their pigments. The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic, multicellular organisms like seaweed and microscopic, unicellular organisms like cyanobacteria. Algal bloom commonly refers to rapid growth of microscopic, unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest.
The biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community.
The salmon run is the time when salmon, which have migrated from the ocean, swim to the upper reaches of rivers where they spawn on gravel beds. After spawning, all Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again. The annual run can be a major event for grizzly bears, bald eagles and sport fishermen. Most salmon species migrate during the fall.
SeaWIFS was a satellite-borne sensor designed to collect global ocean biological data. Active from September 1997 to December 2010, its primary mission was to quantify chlorophyll produced by marine phytoplankton.
Discards are the portion of a catch of fish which is not retained on board during commercial fishing operations and is returned, often dead or dying, to the sea. The practice of discarding is driven by economic and political factors; fish which are discarded are often unmarketable species, individuals which are below minimum landing sizes and catches of species which fishermen are not allowed to land, for instance due to quota restrictions. Discards form part of the bycatch of a fishing operation, although bycatch includes marketable species caught unintentionally. Discarding can be highly variable in time and space as a consequence of changing economic, sociological, environmental and biological factors.
A fishery is an area with an associated fish or aquatic population which is harvested for its commercial value. Fisheries can be marine (saltwater) or freshwater. They can also be wild or farmed.
A fishery is an area with an associated fish or aquatic population which is harvested for its commercial or recreational value. Fisheries can be wild or farmed. Population dynamics describes the ways in which a given population grows and shrinks over time, as controlled by birth, death, and migration. It is the basis for understanding changing fishery patterns and issues such as habitat destruction, predation and optimal harvesting rates. The population dynamics of fisheries is used by fisheries scientists to determine sustainable yields.
The deep chlorophyll maximum (DCM), also called the subsurface chlorophyll maximum, is the region below the surface of water with the maximum concentration of chlorophyll. A DCM is not always present - sometimes there is more chlorophyll at the surface than at any greater depth - but it is a common feature of most aquatic ecosystems, especially in regions of strong thermal stratification. The depth, thickness, intensity, composition, and persistence of DCMs vary widely. The DCM generally exists at the same depth as the nutricline, the region of the ocean where the greatest change in the nutrient concentration occurs with depth.
Ocean deoxygenation is the reduction of the oxygen content of the oceans due to human activities as a consequence of anthropogenic emissions of carbon dioxide and eutrophication driven excess production. It is manifest in the increasing number of coastal and estuarine hypoxic areas, or dead zones, and the expansion of oxygen minimum zones in the world's oceans. The decrease in oxygen content of the oceans has been fairly rapid and poses a threat to all aerobic marine life, as well as to people who depend on marine life for nutrition or livelihood.
David Henry Cushing FRS was an English born fisheries biologist, who is credited with the development the match/mismatch hypothesis as an explanation for reduced fish stocks as associated with climatic variability. As opposed to other important fisheries biologists, such as Daniel Pauly and Carl J. Walters, Cushing was a proponent of keeping fisheries open to the point of collapse.
The Future of Marine Animal Populations (FMAP) project was one of the core projects of the international Census of Marine Life (2000–2010). FMAP's mission was to describe and synthesize globally changing patterns of species abundance, distribution, and diversity, and to model the effects of fishing, climate change and other key variables on those patterns. This work was done across ocean realms and with an emphasis on understanding past changes and predicting future scenarios.
Rising ocean temperatures and ocean acidification are radically altering marine aquatic ecosystems, while freshwater ecosystems are being impacted by changes in water temperature, water flow, and fish habitat loss. Climate change is modifying fish distribution and the productivity of marine and freshwater species. This has impacts on the sustainability of fisheries and aquaculture, on the livelihoods of the communities that depend on fisheries, and on the ability of the oceans to capture and store carbon. The effect of sea level rise means that coastal fishing communities are significantly impacted by climate change, while changing rainfall patterns and water use impact on inland freshwater fisheries and aquaculture. The full relationship between fisheries and climate change is difficult to explore due to the context of each fishery and the many pathways that climate change affects.
The stable ocean hypothesis (SOH) is one of several hypotheses within larval fish ecology that attempt to explain recruitment variability. The SOH is the notion that favorable and somewhat stable physical and biological ocean conditions, such as the flow of currents and food availability, are important to the survival of young fish larvae and their future recruitment. In the presence of stable ocean conditions, concentrations of prey form in stratified ocean layers; more specifically, stable ocean conditions refer to “calm periods in upwelling ecosystems ” that cause the water column to become vertically stratified. The concept is that these strata concentrate both fish larvae and plankton, which results an increase of the fish larvae feeding because of the density-dependent increase in predator-prey interactions. Lasker is attributed with constructing this hypothesis in the late 1970s by building on previous larval fish research and conducting his own experiments. He based the SOH on case studies of clupeid population fluctuations and larval experimentation.
A refuge is a concept in ecology, in which an organism obtains protection from predation by hiding in an area where it is inaccessible or cannot easily be found. Due to population dynamics, when refuges are available, populations of both predators and prey are significantly higher, and significantly more species can be supported in an area.
A whitewater river is classified based on its chemistry, sediments and water colour. Whitewater rivers have high levels of suspended sediments, giving the water a pH that is near-neutral, a high electric conductivity and a pale muddy, coffee and cream-like colour. Whitewater rivers are of great ecological importance and are important to local fisheries. The major seasonal Amazonian floodplains known as várzea receive their water from them.
Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which grow and reproduce rapidly, so a small mass can have a fast rate of primary production. In contrast, terrestrial primary producers, such as mature forests, grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.
Benthic-pelagic coupling are processes that connect the benthic zone and the pelagic zone through the exchange of energy, mass, or nutrients. These processes play a prominent role in both freshwater and marine ecosystems and are influenced by a number of chemical, biological, and physical forces that are crucial to functions from nutrient cycling to energy transfer in food webs.
References
- ↑ Michael Begon; Colin R. Townsend; John L. Harper. (2006). Ecology : from individuals to ecosystems. Blackwell Publishing Ltd. p. 499. ISBN 978-1-4051-1117-1.
