Editing Plankton (section)

== Planktonic relationships ==
===Fish and plankton===

[[Zooplankton]] are the initial prey item for almost all [[fish larva]]e as they switch from their [[yolk sac]]s to external feeding. Fish rely on the density and distribution of zooplankton to match that of new larvae, which can otherwise starve. Natural factors (e.g., current variations, temperature changes) and man-made factors (e.g. river dams, [[ocean acidification]], rising temperatures) can strongly affect zooplankton populations, which can in turn strongly affect fish larval survival, and therefore breeding success.

It has been shown that plankton can be patchy in marine environments where there aren't significant fish populations and additionally, where fish are abundant, zooplankton dynamics are influenced by the fish predation rate in their environment. Depending on the predation rate, they could express regular or chaotic behavior.<ref>{{Cite journal |last1=Medvinsky |first1=Alexander B. |last2=Tikhonova |first2=Irene A. |last3=Aliev |first3=Rubin R. |last4=Li |first4=Bai-Lian |last5=Lin |first5=Zhen-Shan |last6=Malchow |first6=Horst |date=2001-07-26 |title=Patchy environment as a factor of complex plankton dynamics |url=https://link.aps.org/doi/10.1103/PhysRevE.64.021915 |journal=Physical Review E |language=en |volume=64 |issue=2 |pages=021915 |doi=10.1103/PhysRevE.64.021915 |pmid=11497628 |bibcode=2001PhRvE..64b1915M |issn=1063-651X}}</ref>

A negative effect that fish larvae can have on planktonic algal blooms is that the larvae will prolong the blooming event by diminishing available zooplankton numbers; this in turn permits excessive phytoplankton growth allowing the bloom to flourish .<ref name="sciencedirect.com"/>

The importance of both phytoplankton and zooplankton is also well-recognized in extensive and semi-intensive pond fish farming. Plankton population-based pond management strategies for fish rearing have been practiced by traditional fish farmers for decades, illustrating the importance of plankton even in man-made environments.

===Whales and plankton===
Of all animal fecal matter, it is whale feces that is the 'trophy' in terms of increasing nutrient availability. Phytoplankton are the powerhouse of open ocean primary production and they can acquire many nutrients from whale feces.<ref>{{Cite web |title=whale poop and phytoplankton, fighting climate change |url=https://www.ifaw.org/journal/whale-poop-phytoplankton-climate-change |access-date=2022-03-29 |website=IFAW |language=en-US}}</ref> In the marine food web, phytoplankton are at the base of the food web and are consumed by zooplankton & krill, which are preyed upon by larger and larger marine organisms, including whales, so it can be said that whale feces fuels the entire food web.

=== Humans and plankton ===
Plankton have many direct and indirect effects on humans.

Around 70% of the oxygen in the atmosphere is produced in the oceans from [[phytoplankton]] performing photosynthesis, meaning that the majority of the oxygen available for us and other organisms that [[Cellular respiration#Aerobic respiration|respire aerobically]] is produced by plankton.<ref>{{Cite journal |last1=Sekerci |first1=Yadigar |last2=Petrovskii |first2=Sergei |date=2015-12-01 |title=Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change |url=https://doi.org/10.1007/s11538-015-0126-0 |journal=Bulletin of Mathematical Biology |language=en |volume=77 |issue=12 |pages=2325–2353 |doi=10.1007/s11538-015-0126-0 |pmid=26607949 |s2cid=8637912 |issn=1522-9602|hdl=2381/36058 |hdl-access=free }}</ref>

Plankton also make up the base of the marine food web, providing food for all the trophic levels above. Recent studies have analyzed the marine food web to see if the system runs on a [[Top-down and bottom-up design|top-down or bottom-up approach]]. Essentially, this research is focused on understanding whether changes in the food web are driven by nutrients at the bottom of the food web or predators at the top. The general conclusion is that the bottom-up approach seemed to be more predictive of food web behavior.<ref>{{Cite journal |last1=Frederiksen |first1=Morten |last2=Edwards |first2=Martin |last3=Richardson |first3=Anthony J. |last4=Halliday |first4=Nicholas C. |last5=Wanless |first5=Sarah |date=November 2006 |title=From plankton to top predators: bottom-up control of a marine food web across four trophic levels |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2006.01148.x |journal=Journal of Animal Ecology |language=en |volume=75 |issue=6 |pages=1259–1268 |doi=10.1111/j.1365-2656.2006.01148.x |pmid=17032358 |bibcode=2006JAnEc..75.1259F |issn=0021-8790}}</ref> This indicates that plankton have more sway in determining the success of the primary consumer species that prey on them than do the secondary consumers that prey on the primary consumers.

In some cases, plankton act as an intermediate [[Host (biology)|host]] for deadly parasites in humans. One such&nbsp;case is that of [[cholera]], an infection caused by several pathogenic strains of ''[[Vibrio cholerae]]''. These species have been shown to have a symbiotic relationship with chitinous zooplankton species like [[copepod]]s. These bacteria benefit not only from the food provided by the chiton from the zooplankton, but also from the protection from acidic environments. Once the copepods have been ingested by a human host, the chitinous exterior protects the bacteria from the stomach acids in the stomach and proceed to the intestines. Once there, the bacteria bind with the surface of the small intestine and the host will start developing symptoms, including extreme diarrhea, within five days.<ref>{{Cite journal |last1=Lipp |first1=Erin K. |author-link1 = Erin Lipp|last2=Huq |first2=Anwar |last3=Colwell |first3=Rita R. |date=October 2002 |title=Effects of Global Climate on Infectious Disease: the Cholera Model |journal=Clinical Microbiology Reviews |language=en |volume=15 |issue=4 |pages=757–770 |doi=10.1128/CMR.15.4.757-770.2002 |issn=0893-8512 |pmc=126864 |pmid=12364378 }}</ref>