Leptocylindrus is a genus of diatoms belonging to the family Leptocylindraceae. They are long, cylindrical diatoms that are made up of multiple cells in a line (described as a chain). These cells have chloroplast to allow it to produce energy through photosynthesis by taking in sunlight and carbon dioxide to create sugars. the cells are attached at the cell walls called valves, the cell wall is slightly concave on one side and convex on the other so that the other cell wall attached will fit together.
Reproduction
Leptocylindrus reproduction is both asexual and (in some species) sexual. For the specific species Leptocylindrus danicus, it goes through sexual reproduction when its cells are between 3 and 8 micrometers in width (cells above this width go through asexual reproduction). It begins with Leptoclindrus cells splitting into two uneven gametangia. The female gametangia are longer and more brightly colored cell than the male gametangia. Then the process of meiosis occurs, where gametes are produced in the gametangia, the male gametangium (also known as the spermatogonangium) burst to release quadriflagellate spermia, which divide into biflagellate sperma and again into unflagellate sperm (or just sperm), this process takes about twelve hours to complete. After meiosis the female gametangium (or egg) bends at an angle so that the sperm can attach and enter the egg. the site of entry by the sperm starts to swell as the cytoplasm is sent to the area. after fertilization the auxospore forms at this site, the cytoplasm then contracts and valves (distinct halves of the cell wall) form to create the resting spore. these resting spores finally separate from the parent cell and can remain dormant for long periods because of their thick walls. The whole process in total takes about 36 hours to complete. The resting spores under good conditions well then germinate and then well shed there old valves to form a chain with a maximum width of 14 micrometers, and will reproduce asexually until it is between a width of 3 to 8 micrometer where the process begins again.
When Leptocylindrus danicus, and another species Leptocylindrus aporus (which can't reproduce sexually), goes through asexual reproduction by separating to form two distinct halves of different sizes. After sexual and asexual reproduction, the cell wall is soft and halves individually reconstruct themselves. The soft cell wall expands as it matures and eventually forms a silica shell.
The reproduction rate for Leptocylindrus slows or is halted when conditions are unfavorable. these unfavorable conditions include a depleted environment of the elements silicon and nitrogen, and an environment that is above 16 degrees Celsius and below 10 degrees (sexual reproduction seldom happening above 20 degrees). Therefore Leptocylindrus will usually be found reproducing in a nitric rich warm body of water.
Habitat
Leptoclindrus are widely found in many coastal and shelf waters around the world with the exception of extreme polar climates, as species can't survive below 5 degrees Celsius. They are most abundant seasonally in late spring and summer in European seas to the north (abundant in fjords of Norway in summer months), and autumn (and sometimes in parts of spring) around the southern china sea. Leptocylindrus also prefer nitric rich environment because it allows for favorable conditions for sexual reproduction.
The genus Leptocylindrus is one of the most numerically dominant diatoms in the ocean and is a major component of the spring bloom period in southeastern Australia. Leptocylindrus also differ in make up depending on the habitat and environment; for example, it has been observed that there is significant dissimilarity in the composition of the Leptocylindrus microbiome (at the Operational Taxonomic Unit level (OTU)) between Leptocylindrus strains from differing locations along the east coast of Australia, with a higher diversity and more unique OTUs associated with Leptocylindrus strains isolated from the more northern locations compared to those from the south. Different regions harbor distinct bacterial communities.