Algal blooms are rapid increases in algae populations that produce high concentrations of toxins. Although algae generally have low direct pathogenicity, these blooms can harm aquatic wildlife and contaminate seafood with toxins that cause paralysis in humans.

Algal Blooms

Algae have complex cell structures containing different structures of chloroplasts. 

Algae Cell Structure

Seaweeds are macroscopic algae that can be red, brown, or green depending on their photosynthetic pigments, and they differ from land plants by lacking true tissues, organs, and a protective waxy cuticle to prevent desiccation.

Seaweeds

Algae and cyanobacteria are both photosynthetic organisms that can appear similar, but they are distinguished by their cell types: algae are eukaryotic protists, whereas cyanobacteria are prokaryotes.

Comparison of Algae and Cyanobacteria

Algae exhibit diverse reproductive cycles, which can occur through asexual reproduction via mitosis or sexual reproduction using gametes.

Algae Reproduction

Algae have important laboratory and commercial uses; they are a source of agar, which is used as a solidifying agent in microbiological media, and carrageenan, which also serves as a solidifying agent.

Uses of Algae

Algae are classified within the eukaryotic supergroups Chromalveolata (which includes dinoflagellates, diatoms, golden algae, and brown algae) and Archaeplastida (which includes red algae and green algae).

Supergroups of Algae

Algae are autotrophic protists, existing as either unicellular or multicellular organisms, that play a key ecological role by producing approximately 70% of the oxygen and organic matter in aquatic environments.

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Historically, protists have been informally categorized into three distinct groups based on their characteristics: the animal-like protozoans, the plant-like algae, and the fungus-like protists (such as water molds).

Groups of Protists

https://openstax.org/details/books/microbiology/

Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Protozoans are nonphotosynthetic, motile, unicellular eukaryotic organisms that inhabit diverse aquatic and terrestrial environments. While many live independently as free-living organisms, others are parasitic pathogens that cause disease in hosts, or beneficial symbionts that assist their hosts with metabolic functions.

"Animal-Like" Protozoans

"Plant-Like" Algae

Lichens are symbiotic associations between a fungus and a photosynthetic partner, which can be either an alga or a cyanobacterium. They are characteristically slow-growing organisms that can survive for centuries in a variety of habitats.

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