Marine Biology - Marine Algae Lecture Notes

Calculated flashcards covering the diversity, habitats, structures, and ecological roles of marine micro-algae and macro-algae based on the lecture transcript.

Algae

An informal name for a wide diversity of oxygenic, photoautotrophic organisms containing chlorophyll a, representing about 11 major evolutionary lineages, excluding the land plants (Embryophyta).

Cyanobacteria

Prokaryotic algae that include lineages such as the tiny Prochlorococcus and Synechococcus as well as the nitrogen-fixing Trichodesmium.

Diatoms

Eukaryotic micro-algae (phylum Ochrophyta, class Bacillariophyceae) characterized by glass-like siliceous cell walls called frustules.

Net productivity

The amount of carbon organisms incorporate into organic material each year for growth and reproduction, measured in Petagrams of carbon ($PgC$).

Petagram (Pg)

A unit of mass equivalent to $10^{15}$ grams, also referred to as a Gigaton ($Gt$).

Biological Carbon Pump

The process by which sinking dead algal cells and organic matter transfer nutrients and carbon from the surface to the deep ocean and sediments.

Prochlorococcus

The smallest known prokaryotic cyanobacterium (about $0.6\,\mu m$) and a major primary producer in tropical and sub-tropical surface waters.

Epifluorescence microscopy

A technique using ultra-violet light to cause fluorescence in photosynthetic pigments like phycobilins, used to discover Synechococcus in 1979.

Flow cytometry

An identification technique using laser light to detect fluorescence in individual cells passing a detector, used to discover Prochlorococcus in 1987.

Nitrogen fixation

The process of reducing dissolved nitrogen ($N_2$) to ammonia ($NH_3$) for use in organic synthesis, performed by specialized cyanobacteria like Trichodesmium and Crocosphaera.

Heterocyte (Heterocyst)

A specialized cell within certain cyanobacterial filaments, such as Richelia or Scytonema, where nitrogen fixation occurs.

Mixotrophic

An organism, such as certain dinoflagellates, capable of both photosynthesis via chloroplasts and the ingestion of organic particles (phagotrophy).

Peridinin

A carotenoid pigment characteristic of most photosynthetic dinoflagellates.

Saxitoxins

Toxins produced by about 60 species of dinoflagellates, such as Gymnodinium catenatum, which cause paralytic shellfish poisoning (PSP) in humans.

HNLC regions

High Nutrients Low Chlorophyll regions where diatom growth is limited by an insufficient supply of the micronutrient iron.

Coccolithophores

Single-celled phytoplankton in the phylum Haptophyta surrounded by intricate scales of calcite (calcium carbonate).

Dimethyl sulphide

An organic sulphur compound produced by coccolithophores that evaporates and oxidizes in the atmosphere to form cloud seeds, reflecting sunlight.

Seagrasses

Marine aquatic flowering plants, such as Zostera capricorni, that root into muddy sediments and are distinct from algae.

Epiphytes

Micro-algae or macro-algae that grow attached to the surfaces of plants or other algae, such as the relationship between Notheia anomola and Hormosira banksii.

Epipelon and Endopelon

Micro-algal communities associated with sediments; epipelon live on the upper surface, while endopelon live within the sediments.

Epipsammon

The specialized microflora, often dominated by diatoms, found attached to individual sand grains.

Liquid trichome

A chain of undifferentiated cyanobacterial cells, typical of the genus Lyngbya.

Endolithic algae

Algae that live within rock fabric, categorized as chasmoendolithic (in cracks) or euendolithic (actively boring into calcareous rock).

Stromatolites

Layered rock structures formed by microbial consortia, primarily cyanobacteria, that trap sediment and precipitate calcium carbonate during photosynthesis.

Sea-ice algae

Micro-algae, primarily diatoms, that colonize ice crystals and brine pockets in polar regions, providing critical food for krill (Euphausia superba).

Endozoic algae

Mutualistic algae that live within the tissues of animals; they can be intercellular (between cells) or intracellular (within cells).

Zooxanthellae

Intracellular endosymbiotic dinoflagellates, usually of the genus Symbiodinium, that provide corals with photosynthetic products.

Siphonous alga

An alga compromised of a single large cell containing continuous cytoplasm with numerous nuclei and organelles, such as Codium or Caulerpa.

Biofouling

The undesirable growth of marine organisms, such as Enteromorpha or Undaria pinnatifida, on human-made structures like ship hulls.

Adelphoparasite

A parasitic red alga that is closely related to its host and shares a recent evolutionary origin (e.g., Hypneocolax on Hypnea).

Chlorophyll d

A pigment found in the cyanobacterium Acaryochloris that captures far-red and infra-red light, allowing survival in extremely low-light environments underneath sea squirts.