''Pleurophycus gardneri'' is a species of

brown alga Brown algae (: alga) are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar reg ...

. It is a deciduous kelp, primarily found in lower, rocky inter-tidal and shallow, rocky sub-tidal locations and is one of the most abundant kelps found within the Pleurophycus Zone (roughly 30-45m depth). It is not commonly present deeper in the ocean than 30m and is considered a stipitate kelp. ''P. gardneri'' forms aggregates of densities up to 10m⁻² . These kelp beds reside below giant kelp forests, and were therefore often overlooked by researchers for many years. This kelp has a range from Central California to British Columbia, Canada, with a lifespan of only 3 – 6 years. The family of ''P. gardneri'' was previously believed to be Laminariaceae and not Alariaceae, but molecular data supports this particular kelp to be of the family

Alariaceae Alariaceae are a family of brown algae in the order Laminariales. Genera * '' Alaria'' * '' Aureophycus'' * '' Eualaria'' * '' Lessoniopsis'' * '' Pleurophycus'' * '' Pterygophora'' * '' Undaria'' (e.g. wakame) * '' Undariella'' Distri ...

. ''P. gardneri'' has been referred to as Tender Kelp (1980) or Sea spatula (1985).

Interactions with other species

''Pleurophycus gardneri'' is a habitat to many species of

amphipod Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...

, and most commonly supports species specific to stipe burrowing. Amphipods decrease the lifespan of this kelp due to damages caused by burrowing; any breaks in the plants'

holdfast Holdfast most often refers to: *Holdfast (biology), a root-like structure that anchors aquatic sessile organisms to their substrate *Holdfast (tool), a tool used to secure a workpiece to a workbench or anvil Holdfast or hold fast may also refer t ...

up to its stipe will kill the plant, hence its heightened mortality rate due to stipe burrowing amphipods. Breaks above the abscission zone of the plants' frond will not kill the plant, but may still decrease fitness.

Reproduction

''Pleurophycus gardneri'' reproduces in the same way as all other

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

. It has

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

s and a microscopic haploid

gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the se ...

stage. Mature algal blades have a thick mid-rib which contain sori for reproduction. A

sorus A sorus (: sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (: coenosori) is a compound sorus composed of multiple, fused sori. Etymology This Neo-Latin word is from Ancient Greek � ...

is able to produce gametes for the kelp.

Perennial characteristics

Mature algal blades have a length of roughly 150 cm. Annual banding can be found in the stipe of the plant due to its deciduous nature, which researchers often use to identify plant age. ''P. gardneri'' loses all foliage by late fall and then soon thereafter (after a roughly two-week dormancy) begins to grow new blades. For new blades to begin growing, light must be present. Premature blade deterioration and breakages were seen as a direct result of warmed ocean temperatures. It is believed that temperatures around 14-15 C trigger blade deterioration. Following an

El Niño EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...

, this kelp was recorded to have prematurely dropped blades.

References

{{Taxonbar, from=Q29347903 Alariaceae