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The garganey (Spatula querquedula) is a small dabbling duck.It breeds in much of Europe and across the Palearctic, but is strictly migratory, with the entire population moving to Africa, India (in particular Santragachi), Bangladesh (in the natural reservoirs of Sylhet district) and Australasia during the winter of the Northern hemisphere, [2] where large flocks can occur.
The upper value, 5.0, is unusual, even for large fish, [7] though it occurs in apex predators of marine mammals, such as polar bears and killer whales. [8] As a point of contrast, humans have a mean trophic level of about 2.21, about the same as a pig or an anchovy. [9] [10]
The diagram shows: (1) Larval and juvenile stages of fishes from many ocean habitats aggregate in slicks in order to capitalize on dense concentrations of prey (2, phytoplankton, 3, zooplankton, 4, larval invertebrates, 5, eggs, and 6, insects).
A molecular phylogenetic study comparing mitochondrial DNA sequences published in 2009 found that the genus Anas, as then defined, was non-monophyletic. [2] Based on this published phylogeny, the genus Anas was split into four monophyletic genera with 10 species moved into the resurrected genus Spatula. [3]
Dead diatoms drift to the ocean floor where, over millions of years, the remains of their frustules can build up as much as half a mile deep. [64] Diatoms have relatively high sinking speeds compared with other phytoplankton groups, and they account for about 40% of particulate carbon exported to ocean depths. [60] [65] [62]
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. [1] [2] 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.
Three main processes (or pumps) that make up the marine carbon cycle bring atmospheric carbon dioxide (CO 2) into the ocean interior and distribute it through the oceans. These three pumps are: (1) the solubility pump, (2) the carbonate pump, and (3) the biological pump.
Pelagic zones. The ocean can be conceptualized as being divided into various zones, depending on depth, and presence or absence of sunlight.Nearly all life forms in the ocean depend on the photosynthetic activities of phytoplankton and other marine plants to convert carbon dioxide into organic carbon, which is the basic building block of organic matter.