Editing Kelp forest (section)

== Kelp ==
{{main|Kelp}}

The term [[kelp]] refers to [[marine algae]] belonging to the [[Order (biology)|order]] Laminariales (phylum: [[Ochrophyta]]). Though not considered a taxonomically diverse order, kelps are highly diverse structurally and functionally.<ref name="Steneck 2002" /> The most widely recognized species are the giant kelps (''[[Macrocystis]]'' spp.), although numerous other genera such as ''[[Laminaria]]'', ''[[Ecklonia]]'', ''[[Lessonia (alga)|Lessonia]]'', ''[[Nereocystis]]'', ''[[Alaria (alga)|Alaria]]'', and ''[[Eisenia (alga)|Eisenia]]'' are described.

A wide range of sea life uses kelp forests for protection or food, including fish. In the North Pacific kelp forests, particularly [[Sebastidae|rockfish]], and many [[invertebrate]]s, such as [[amphipod]]s, [[shrimp]], [[marine snail]]s, [[bristle worm]]s, and [[brittle star]]s. Many marine mammals and birds are also found, including seals, sea lions, whales, [[sea otter]]s, gulls, terns, [[snowy egret]]s, [[great blue heron]]s, and cormorants, as well as some shore birds.<ref>[http://oceanservice.noaa.gov/facts/kelplives.html Kelp forests provide habitat for a variety of invertebrates, fish, marine mammals, and birds] {{Webarchive|url=https://web.archive.org/web/20170909185527/http://oceanservice.noaa.gov/facts/kelplives.html |date=2017-09-09 }} NOAA. Updated 11 January 2013. Retrieved 15 January 2014.</ref>

Frequently considered an [[ecosystem engineer]], kelp provides a physical substrate and habitat for kelp forest communities.<ref>{{Cite journal |last1=Jones |first1=Clive G. |last2=Lawton |first2=John H. |last3=Shachak |first3=Moshe |date=October 1997 |title=Positive and Negative Effects of Organisms as Physical Ecosystem Engineers |url=http://doi.wiley.com/10.1890/0012-9658(1997)078&#91;1946:PANEOO&#93;2.0.CO;2 |journal=Ecology |volume=78 |issue=7 |pages=1946–1957 |doi=10.1890/0012-9658(1997)078[1946:PANEOO]2.0.CO;2 |issn=0012-9658 |access-date=2024-10-05 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007145523/https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/0012-9658%281997%29078%5B1946%3APANEOO%5D2.0.CO%3B2 |url-status=live |url-access=subscription }}</ref> In algae (kingdom [[Protista]]), the body of an individual organism is known as a [[thallus]] rather than as a plant (kingdom [[Plantae]]). The morphological structure of a kelp thallus is defined by three basic structural units:<ref name="Dayton 1985a" />
* The [[holdfast (biology)|holdfast]] is a root-like mass that anchors the thallus to the sea floor, though unlike true roots it is not responsible for absorbing and delivering nutrients to the rest of the thallus.
* The [[Stipe (botany)|stipe]] is analogous to a plant stalk, extending vertically from the holdfast and providing a support framework for other morphological features.
* The [[fronds]] are leaf- or blade-like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity.
In addition, many kelp species have [[pneumatocyst]]s, or gas-filled bladders, usually located at the base of fronds near the stipe. These structures provide the necessary buoyancy for kelp to maintain an upright position in the water column.

The environmental factors necessary for kelp to survive include hard substrate (usually rock or sand), high nutrients (e.g., nitrogen, phosphorus), and light (minimum annual [[irradiance]] dose > 50 E m<sup>−2</sup><ref name="Druehl 1981">{{Cite conference |last1=Lüning |first1=Klaus |last2=tom Dieck |first2=Inka |date=1990 |editor-last=Garbary |editor-first=David J. |editor2-last=South |editor2-first=G. Robin |conference=Evolutionary Biogeography of the Marine Algae of the North Atlantic |title=The Distribution and Evolution of the Laminariales: North Pacific — Atlantic Relationships |url=http://link.springer.com/10.1007/978-3-642-75115-8_10 |location=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |pages=187–204 |doi=10.1007/978-3-642-75115-8_10 |isbn=978-3-642-75117-2 |access-date=2024-10-05 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007145524/https://link.springer.com/chapter/10.1007/978-3-642-75115-8_10 |url-status=live |url-access=subscription }}</ref>). Especially productive kelp forests tend to be associated with areas of significant oceanographic [[upwelling]], a process that delivers cool, nutrient-rich water from depth to the ocean's [[mixed layer|mixed surface layer]].<ref name="Druehl 1981" /> Water flow and turbulence facilitate nutrient assimilation across kelp fronds throughout the water column.<ref>{{Cite journal |last=Wheeler |first=W. N. |date=1980 |title=Effect of boundary layer transport on the fixation of carbon by the giant kelp Macrocystis pyrifera |url=http://link.springer.com/10.1007/BF00397128 |journal=Marine Biology |language=en |volume=56 |issue=2 |pages=103–110 |doi=10.1007/BF00397128 |bibcode=1980MarBi..56..103W |issn=0025-3162 |access-date=2024-10-06 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007145638/https://link.springer.com/article/10.1007/BF00397128 |url-status=live |url-access=subscription }}</ref> Water clarity affects the depth to which sufficient light can be transmitted. In ideal conditions, giant kelp (''Macrocystis'' spp.) can grow as much as 30–60&nbsp;cm vertically per day. Some species, such as ''Nereocystis'', are [[annual plant|annual]]s, while others such as ''Eisenia'' are [[perennial plant|perennial]]s, living for more than 20 years.<ref>{{Cite journal |last1=Steneck |first1=Robert S. |last2=Dethier |first2=Megan N. |date=April 1994 |title=A Functional Group Approach to the Structure of Algal-Dominated Communities |url=https://www.jstor.org/stable/3545860 |journal=Oikos |volume=69 |issue=3 |pages=476 |doi=10.2307/3545860 |jstor=3545860 |bibcode=1994Oikos..69..476S |access-date=2024-10-06 |archive-date=2020-02-14 |archive-url=https://web.archive.org/web/20200214173943/https://www.jstor.org/stable/3545860 |url-status=live |url-access=subscription }}</ref> In perennial kelp forests, maximum growth rates occur during upwelling months (typically spring and summer) and die-backs correspond to reduced nutrient availability, shorter photoperiods, and increased storm frequency.<ref name="Dayton 1985a" />

Kelps are primarily associated with [[temperate]] and [[arctic]] waters worldwide. Of the more dominant genera, ''Laminaria'' is mainly associated with both sides of the [[Atlantic Ocean]] and the coasts of [[China]] and [[Japan]]; ''Ecklonia'' is found in [[Australia]], [[New Zealand]], and [[South Africa]]; and ''Macrocystis'' occurs throughout the northeastern and southeastern [[Pacific Ocean]], [[Southern Ocean]] archipelagos, and in patches around Australia, New Zealand, and South Africa.<ref name="Dayton 1985a" /> The region with the greatest diversity of kelps (>20 species) is the northeastern Pacific, from north of [[San Francisco, California]], to the [[Aleutian Islands]], Alaska.

Although kelp forests are unknown in tropical surface waters, a few species of ''Laminaria'' have been known to occur exclusively in tropical deep waters.<ref>{{Cite book |last=Joly |first=Aylthon Brandão |url=https://openlibrary.org/books/OL4960200M/Two_Brazilian_Laminarias |title=Two Brazilian Laminarias |date=1967 |publisher=Instituto de Pesquisas da Marinha |location=Rio de Janeiro |pages=1–7 |ol=4960200M |access-date=2024-10-06 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007145533/https://openlibrary.org/books/OL4960200M/Two_Brazilian_Laminarias |url-status=live }}</ref><ref>Petrov, J.E., M.V. Suchovejeva and G.V. Avdejev. 1973. New species of the genus ''Laminaria'' from the Philippine Sea. Nov Sistem. Nizch. Rast. 10: 59–61.</ref> This general absence of kelp from the tropics is believed to be mostly due to insufficient nutrient levels associated with warm, [[oligotroph]]ic waters.<ref name="Dayton 1985a" /> One recent study spatially overlaid the requisite physical parameters for kelp with mean oceanographic conditions and produced a model predicting the existence of subsurface kelps throughout the tropics worldwide to depths of {{Convert|200|m|ft|abbr=on}}. For a hotspot in the [[Galapagos Islands]], the local model was improved with fine-scale data and tested; the research team found thriving kelp forests in all eight of their sampled sites, all of which had been predicted by the model, thus validating their approach. This suggests that their global model might actually be fairly accurate, and if so, kelp forests would be prolific in tropical subsurface waters worldwide.<ref name=" Graham et al. 2007"/> The importance of this contribution has been rapidly acknowledged within the scientific community and has prompted an entirely new trajectory of kelp forest research, highlighting the potential for kelp forests to provide marine organisms spatial refuge under climate change and providing possible explanations for evolutionary patterns of kelps worldwide.<ref>{{Cite journal |last=Santelices |first=Bernabé |date=2007-12-04 |title=The discovery of kelp forests in deep-water habitats of tropical regions |journal=Proceedings of the National Academy of Sciences |language=en |volume=104 |issue=49 |pages=19163–19164 |doi=10.1073/pnas.0708963104 |doi-access=free |issn=0027-8424 |pmc=2148260 |pmid=18042707|bibcode=2007PNAS..10419163S }}</ref>