Unknown species
Spreading as a visible blue-green film across the substrate and glass of the Seagrass Meadow, this photosynthetic microbial growth colonized the system after sand-turning disturbance declined and is grazed by the Mottled Shore Crab and targeted by the June 2026 Mud Crab introduction.
This record tracks a visible cyanobacterial surface growth community in the Seagrass Meadow. The exact genus and species are unresolved; the growth is described as cyanobacterial based on visual appearance and context but has not been microscopically confirmed. The growth is not Nostoc (per direct user clarification). Transient cyanobacteria-like appearances occurred at various points in the system's earlier history; persistent surface growth established in November 2025. Mottled Shore Crab is documented as a grazer reducing the cyanobacterial extent. Mud Crabs were added to the Seagrass Meadow in June 2026 partly to disrupt the growth through sediment disturbance. Population status is Uncertain.
Cyanobacteria are photosynthetic prokaryotes, bacteria that photosynthesize. Despite being commonly called "blue-green algae," they are bacteria, not algae; they share no evolutionary relationship with true algae. Cyanobacteria were among the first photosynthetic organisms on Earth and played a key role in oxygenating the early atmosphere. They are found in virtually every aquatic and terrestrial environment.
Cyanobacteria grow as unicellular, colonial, or filamentous forms, often producing visible mats, films, or clumps on substrate and glass surfaces. Blue-green coloration is typical, though brown, black, or olive-green growth is also possible depending on species and light conditions. Filamentous forms can fragment and colonize new surfaces; colonial forms can spread horizontally across substrate.
In aquatic systems, cyanobacteria opportunistically colonize substrate surfaces when conditions favor them: adequate light, available dissolved nutrients (particularly phosphorus and nitrogen), and reduced physical disturbance. In natural settings, bioturbation, the physical mixing of substrate by burrowing animals and detritivores, limits cyanobacterial mat development by continuously disrupting the surface layer. When bioturbation is reduced, cyanobacteria can establish and spread more readily.
In marine aquariums and closed systems, cyanobacterial surface growth is common and is typically associated with elevated nutrients, reduced water circulation over the substrate, and insufficient grazing or bioturbation pressure.
Some cyanobacterial genera (notably Anabaena and Trichodesmium) fix dissolved atmospheric nitrogen into biologically available forms, adding nitrogen to the system from the air. Whether the miniBIOTA cyanobacterial growth includes nitrogen-fixing taxa is unknown.
Some cyanobacterial genera produce toxins (cyanotoxins) that can harm animals, particularly through ingestion or skin contact. Not all cyanobacteria produce toxins, and even toxin-producing genera do not produce toxins under all conditions. Whether the miniBIOTA growth produces toxins is unknown. No toxicity events have been documented.
The miniBIOTA cyanobacteria occupy substrate surfaces and potentially vertical surfaces within the Seagrass Meadow. The growth forms a visible blue-green film or mat across sand and hard surfaces. Transient surface growth appeared at various earlier points; persistent, prolific growth established in November 2025 and continued through mid-2026.
Cyanobacteria function as photosynthetic producers in the Seagrass Meadow, converting light and dissolved nutrients into microbial biomass. As a surface mat, the growth contributes to the base of the food web and can be consumed by generalist grazers.
The growth also represents a succession dynamic: in the absence of adequate bioturbation (sand-turning by detritivores), cyanobacterial mats can spread and outcompete other producers for substrate. The mat layer can shade underlying substrate, alter local oxygen dynamics, and influence which other organisms can establish.
Mottled Shore Crab has been documented grazing directly in the cyanobacteria and macroalgae clump, with the cyanobacterial extent notably reduced following the crab's activity (March 26, 2026). This is the only confirmed predator or grazer of this growth on record in miniBIOTA.
Mud Crabs were added to the Seagrass Meadow on June 4, 2026, partly with the intention that their digging and foraging behavior might disrupt cyanobacterial surface growth through increased sediment disturbance. Whether this intervention reduced the growth is not yet documented.
Cyanobacteria were not intentionally introduced to miniBIOTA. The growth colonized the Seagrass Meadow spontaneously. No introduction date, source, or method is on record. Transient cyanobacteria-like appearances occurred at various earlier points but did not persist; the growth became a persistent ecological feature of the Seagrass Meadow starting in November 2025.
Cyanobacteria-like growth is tracked as a visible producer and surface growth layer in the Seagrass Meadow. Transient cyanobacteria-like growth occurred at various points before 2025 but did not persist. Persistent growth established in November 2025 and became prolific by mid-2026. A hypothesis exists that reduced substrate disturbance after Common Atlantic Marginella removal (2024) may have contributed to cyanobacterial growth, but the timing gap of over a year between Marginella removal and persistent growth onset is significant and the relationship is unresolved. As of June 4, 2026, Marginella reintroduction had been attempted but no individuals were found. Mottled Shore Crab grazing reduced the cyanobacterial extent in March 2026. Mud Crabs were introduced June 4, 2026, partly to disrupt the growth through bioturbation; outcome unresolved. By June 14, 2026, following the June 12 major hermit crab introduction and June 13 wave system strengthening, the growth was visually less established and beginning to break apart. By June 18, 2026, the mat had fragmented into smaller, discrete clumps and is described as clearly losing dominance. Two attributed drivers: sustained hermit crab disruption and grazing, and stronger wave currents.
Photosynthetic microbial producer forming surface films and mats on substrate and glass in the Seagrass Meadow. Colonizes available substrate when bioturbation pressure and grazing pressure are insufficient to disrupt the surface layer. Some cyanobacterial genera fix atmospheric nitrogen, adding bioavailable nitrogen to the system; whether this occurs in miniBIOTA is unknown.
As a microbial photosynthetic surface community, cyanobacterial mat development is favored by reduced physical disturbance of the substrate, available light, and dissolved nutrients. In closed marine systems, cyanobacterial growth is associated with elevated nutrients and insufficient bioturbation or grazing pressure. The exact tolerance ranges of the miniBIOTA cyanobacterial growth are unknown.
Cyanobacteria reproduce by binary fission; cells divide continuously under suitable conditions. Filamentous forms can fragment and spread by passive transport to new surfaces. The mat community expands laterally across available substrate when bioturbation and grazing pressure are insufficient.
Photosynthetic microbial producer contributing surface-layer primary production to the Seagrass Meadow. When established extensively, the mat can shade underlying substrate and alter surface conditions for other organisms. Grazed by Mottled Shore Crab, which reduced cyanobacterial extent following grazing activity in March 2026. Mud Crabs added June 2026 with the intent of disrupting the growth through sediment bioturbation; outcome unresolved. No symbiotic relationships documented.
Follow this species across the habitats where it currently appears in the miniBIOTA biosphere.
