One of the most fundamental and precarious stages in the life history of a marine benthic alga is the colonization of a new substratum. For the majority of algae this is achieved by the formation and detachment of different types of highly specialized reproductive propagules which are then dispersed via the pelagic zone. This paper reviews the process of “settlement”, “attachment” and “establishment” of these propagules. Particular attention is given to the influence of substratum surface properties, both physical and chemical, on these processes, along with aspects of the derivation, chemical composition, mechanisms of release and mode of action of the various adhesives secreted by the attaching spores and germlings.

https://www.tandfonline.com/doi/pdf/10.1080/00071619200650281

The settlement, attachment and establishment of marine algal spores

Seaweed dispersal is discussed in relation to the properties of the propagules, the parent plant and the water motion The magnitude of water flow velocities is overwhelmingly important Even motile propagules have little control over their destiny The fate of both liberated propagules and drifting plants is discussed in relation to dispersal distance and the likelihood of successful colonization at journey's end Analogies are drawn between the dispersion and drift of algal propagules and that of smoke particles and fungal spores The fecundity of the parent plant, the point and mode of propagule release are also influential Many larger plants have release mechanisms that limit rather than enhance dissemination Moreover, contrary to accepted dogma, invertebrates that consume or transport spores also tend to limit rather than extend dispersal range The relative merits of local consolidation vs widespread dispersal are discussed

https://www.tandfonline.com/doi/pdf/10.1080/00071619200650271

Dispersal by macroalgae

It has been proposed that a 'bank of microscopic forms' functions as a survival mechanism for benthc macroalgae, m some ways analogous to the 'seed bank' of terrestrial plants. Four aspects related to this hypothesis are examined here, namely (1) origin and morphology of the structures forming banks, (2) their specific compositions, (3) environmental conditions that allow their survival in a state of suspended growth, and conditions that trigger reinitiation of growth; and (4) losses from the banks by diverse causes Although the structures at which growth suspension occurs are of very different morphologies, and probably are also different in their capacities of temporal displacement, both types of banks are regulated by similar environmental factors and subjected to similar types of constraints. Some important differences between the 2 banks are likely to stem from the lesser longevity of the algal microscopic stages, which would limit the duration of banks of microscopic forms

/pdf/banks-of-algal-microscopic-forms-hypotheses-on-their-57rgrdxr0s.pdf

Banks of algal microscopic forms: hypotheses on their functioning and comparisons with seed banks

In the Abrolhos Islands, site of a high-latitude coral reef, the net rate of community calcification is high but growth of frame-building corals is reduced. Our studles suggest that the latitudinal limits of coral reef development are often set by competition of macroalgae with corals, and that macroalgae are favoured at these latitudes by high nutrient concentrations, moderate water temperatures (for macroalgae) and possibly by reduced grazing pressure, while coral growth is reduced by temperatures which, for reef corals, are low.

/pdf/latitudinal-limits-of-coral-reef-growth-s3u42oltei.pdf

Latitudinal limits of coral reef growth

The role of fishes in the organization of a Mediterranean sublittoral community

Size variation in 92 populations of carpospores and tetraspores representing 57 tropical benthic algal taxa has been investigated. One size class predominates in each sample, but there is considerable variation in spore size in all populations of carpospores and tetraspores. Spore size is therefore not a useful taxonomic character at the species level despite the considerable range within the division Rhodophyta. Nevertheless, advanced Florideophyceae form chiefly tetrahedral tetrasporangia with large spores; less advanced groups generally form cruciate or zonate tetrasporangia with smaller spores. Carpospores are generally larger than tetraspores. The mucilage sheaths of a representative number of species comprising 56 populations of carpospores and tetraspores were studied. The diameter of the spore with its mucilage sheath is frequently twice the diameter of the spore excluding the sheath.

Systematic significance of spore size in the Florideophyceae (Rhodophyta)

Seasonal growth and reproduction of intertidal algae in the townsville region (Queensland, Australia)

Data on the periodicity of carpospore and tetraspore discharge in 48 tropical benthic algal taxa from 25 genera are given. The time of maximum spore output in the laboratory occurred when populations on the shore would be submerged in sea water. Depending on the taxon, maximum spore output took place in the early morning, in the afternoon, or late in the evening. In taxa with small-sized spores, spore discharge took place during either the morning or the evening, or in a few cases during both periods, and high spore output generally occurred during the lower of the two high waters which occur daily in the Townsville region. In taxa with large-sized spores, and which generally inhabit the lower intertidal levels, spore liberation took place only in the afternoon, and high spore output then occurred during either the lower or the higher of the two high waters.

Yinam Ngan

Papers

Systematic significance of spore size in the Florideophyceae (Rhodophyta)

Seasonal growth and reproduction of intertidal algae in the townsville region (Queensland, Australia)

Periodicity of spore discharge in tropical Florideophyceae (Rhodophyta)

The intertidal algae of the mainland coast in the vicinity of Townsville, Queensland