Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's 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 the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest.
Phytoplankton are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words φυτόν, meaning 'plant', and πλαγκτός, meaning 'wanderer' or 'drifter'.
Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
Sir Alister Clavering Hardy was an English marine biologist, an expert on marine ecosystems spanning organisms from zooplankton to whales. He had the artistic skill to illustrate his books with his own drawings, maps, diagrams, and paintings.
Holoplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their life cycle in the benthic zone. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists.
Meroplankton are a wide variety of aquatic organisms which have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organism. Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle.
Thin layers are concentrated aggregations of phytoplankton and zooplankton in coastal and offshore waters that are vertically compressed to thicknesses ranging from several centimeters up to a few meters and are horizontally extensive, sometimes for kilometers. Generally, thin layers have three basic criteria: 1) they must be horizontally and temporally persistent; 2) they must not exceed a critical threshold of vertical thickness; and 3) they must exceed a critical threshold of maximum concentration. The precise values for critical thresholds of thin layers has been debated for a long time due to the vast diversity of plankton, instrumentation, and environmental conditions. Thin layers have distinct biological, chemical, optical, and acoustical signatures which are difficult to measure with traditional sampling techniques such as nets and bottles. However, there has been a surge in studies of thin layers within the past two decades due to major advances in technology and instrumentation. Phytoplankton are often measured by optical instruments that can detect fluorescence such as LIDAR, and zooplankton are often measured by acoustic instruments that can detect acoustic backscattering such as ABS. These extraordinary concentrations of plankton have important implications for many aspects of marine ecology, as well as for ocean optics and acoustics. Zooplankton thin layers are often found slightly under phytoplankton layers because many feed on them. Thin layers occur in a wide variety of ocean environments, including estuaries, coastal shelves, fjords, bays, and the open ocean, and they are often associated with some form of vertical structure in the water column, such as pycnoclines, and in zones of reduced flow.
Calanus finmarchicus is a species of copepod and a component of the zooplankton, which is found in enormous amounts in the northern Atlantic Ocean.
The Continuous Plankton Recorder (CPR) Survey is one of the longest running marine biological monitoring programmes in the world. Started in 1931 by Sir Alister Hardy and Sir Cyril Lucas, the Survey provides marine scientists and policy-makers with measures of plankton communities, coupled with ocean physical, biological and chemical observations, on a pan-oceanic scale. The Survey is a globally recognised leader on the impacts of environmental change on the health of our oceans.
The SCARSouthern Ocean Continuous Plankton Recorder (SO-CPR) Survey was established in 1991 by the Australian Antarctic Division,of Environment, Water Heritage and the Arts, to map the spatial-temporal patterns of zooplankton and then to use the sensitivity of plankton to environmental change as early warning indicators of the health of the Southern Ocean. It also serves as reference for other Southern Ocean and Antarctic monitoring programs.
In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below, which is referred to as the biological pump. Export production is the amount of organic matter produced in the ocean by primary production that is not recycled (remineralised) before it sinks into the aphotic zone. Because of the role of export production in the ocean's biological pump, it is typically measured in units of carbon. The term was coined by explorer William Beebe as observed from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in the aphotic zone, particularly for organisms that live very deep in the water column.
Bacterioplankton refers to the bacterial component of the plankton that drifts in the water column. The name comes from the Ancient Greek word πλανκτος, meaning "wanderer" or "drifter", and bacterium, a Latin term coined in the 19th century by Christian Gottfried Ehrenberg. They are found in both seawater and freshwater.
A video plankton recorder (VPR) is towed underwater video microscope system, which photographs small to fine-scale structure of plankton, from 50 micrometers and up to a few centimeters in size. A VPR consists of five general components: cameras, strobe, additive sensor and flight control, underwater platform and interface software for plankton identification.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
Alan Reece Longhurst is a British-born Canadian oceanographer who invented the Longhurst-Hardy Plankton Recorder, and is widely known for his contributions to the primary scientific literature, together with his numerous monographs, most notably the "Ecological Geography of the Sea". He led an effort that produced the first estimate of global primary production in the oceans using satellite imagery, and also quantified vertical carbon flux through the planktonic ecosystem via the biological pump. More recently, he has offered a number of critical reviews of several aspects of fishery management science and climate change science.
A plankton net is equipment used for collecting samples of plankton in standing bodies of water. It consists of a towing line and bridles, nylon mesh net, and a cod end. Plankton nets are considered one of the oldest, simplest and least expensive methods of sampling plankton. The plankton net can be used for both vertical and horizontal sampling. It allows researchers to analyse plankton both quantitatively and qualitatively in water samples from the environment.
The North South Atlantic Training Transect (NoSoAT) is a program developed by the Alfred Wegener Institute (AWI), the Strategic Marine Alliance for Research and Training (SMART), and the Partnership for Observation of the Global Oceans (POGO) to further the education and practical training of postgraduate students in climate and marine sciences. Each year, about 30 students are selected through a rigorous application process to join a voyage from Bremerhaven, Germany to Cape Town, South Africa aboard the RV Polarstern. The month-long course provides students with relevant lectures and projects, including hands-on training with atmospheric and oceanographic equipment, and instruction on data processing and analysis.
Graeme C. Hays is a British and Australian marine ecologist known for his work with sea turtles and plankton. He is the Alfred Deakin Professor of Marine Science at Deakin University, Australia.
Ana María Gayoso was an Argentine marine biologist, a specialist in study of marine phytoplankton, best known for being the first scientist to describe phytoplankton in the Bahía Blanca Estuary, and to initiate the sustained long-term oceanographic dataset in this ecosystem. She made significant contributions to the understanding of harmful algal blooms caused by toxic dinoflagellate species in the Patagonian gulfs, and was the first scientist to describe high abundances of the coccolithophore Emiliania huxleyi in the Argentine Sea, a key component in the primary productivity along the Patagonian Shelf Break front in the SW South Atlantic. She started the most extensive (1978-present) long-term database of phytoplankton and physico-chemical variables in South America, in a fixed monitoring site in the Bahía Blanca Estuary. She died on 28 December 2004 in Puerto Madryn.
