''Calanus sinicus'' is a copepod found in the northwest Pacific.

Description

The female ''C. sinicus'' generally ranges from about . The male generally ranges between about . For adults and copepodite stages IV and above, lower temperatures result in longer prosomes.

Distribution

''C. sinicus'' is found in the northwest Pacific, off of the east coast of Asia to the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phi ...

Ecology

Life cycle and reproduction

''C. sinicus'' reproduces throughout the year. There are generally two peaks in reproduction. In the southern

Yellow Sea The Yellow Sea is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. It is one of four seas named after common colour ter ...

, these peaks occur from May to July and from November to January. These peaks occur when the temperatures throughout the water column fall into its preferred temperature range of . It can tolerate ranges between for limited periods of time, and can reproduce between about . It is likely that there are two different reproductive strategies carried out during spring and autumn. In the first reproductive period, during spring, the average prosome length is high, which allows it to produce more eggs around the time of the phytoplankton bloom. During autumn, on the other hand, accumulated energy is likely used to finance reproduction. Spawning occurs at the surface during the night and dawn, with peak spawning occurring during the latter. The depth at which eggs are found varies seasonally; a study in the Sea of Japan found that eggs generally occurred at about in depth in August and September, about in November, about in June, and about in March. The depth at which eggs are found may be related to the avoidance of cannibalism by late copepodite stages and adults, as, in some cases, a lack of overlap between the vertical distribution of eggs and potential cannibals has been observed. The eggs hatch into nauplii in about one day. From August onwards, the population declines and its distribution shrinks. During this time, it is found in cooler waters; it oversummers, for example, in the Yellow Sea Cold Bottom Water, where temperatures are usually below . Adults, stage V copepodites, and some stage IV copepodites are found in the colder bottom waters, whereas copepodite stages I through III are found in the middle layer, where temperatures are between about . During this time, it still feeds actively.

Relationship with humans

''C. sinicus'' is an important food of

anchovies An anchovy is a small, common forage fish of the family Engraulidae. Most species are found in marine waters, but several will enter brackish water, and some in South America are restricted to fresh water. More than 140 species are placed in 1 ...

sandeel Sand eel or sandeel is the common name used for a considerable number of species of fish. While they are not true eels, they are eel-like in their appearance and can grow up to in length. Many species are found off the western coasts of Europe ...

s, and

sardine "Sardine" and "pilchard" are common names for various species of small, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century, a folk etymology says it comes from the It ...

s, which are important commercially.

References

{{Taxonbar, from=Q6552371 Calanoida Crustaceans described in 1962