the immortal red crust

  
  FHL Marine Botany  ::::::::::::::::::::::::::::::   Taxonomy | Habitat | Morphology | Life History | Ecology | Overgrowth
 

 

OVERGROWTH and anabiosis

Hildenbrandia demonstrates the remarkable ability to survive for long periods of time underneath other things, including animals, vegetables, and minerals. In other crustose algae, this ability is a function of pit connections and hypothallic communication; resources can be marshalled from the exposed thallus to the overgrown thallus, or certain sections of the thallus can just be cut off from the rest of the individual (1). But Hildenbrandia lacks a distinct hypothallus, and its pit connections do not seem to serve as conduits for resources or hormones (1,2). Hildenbrandia's capacity for surviving overgrowth seems to be an example of anabiosis (3, 4).

 

[O.1] Hildenbrandia occidentalis sandwiched between a rock and a green sponge, collected from Cattle Point, San Juan Island, WA. Note that all cells have retained their pigment and show no signs of stress (e.g., bleaching, see next photograph). The thallus is approx. 700 µm thick.

 

[O.2] Hildenbrandia occidentalis overgrowing another encrusting alga, whose cells are now bleached. This alga has presumably not survived overgrowth. Note the layer of sand in between the two individual.

 

[O.3] Hildenbrandia rubra covered by Cladophora sp. and Scytosiphon sp. in a tide pool at Botanical Beach, BC. Note that the littorine snails have elected to feed on the small green filaments.

 

[O.4] Hildenbrandia occidentalis being overgrown by coralline crusts, purple sponge and various other algae at Botanical Beach, BC.

  

 

 

 

 

 
 
   

 

  1. Pueschel, C.M. 1982. Secondary pit connections in Hildenbrandia (Rhodophyta, Hildenbrandiales).European Journal of Phycology 23:1, pp. 25 - 32.
  2. Cabioch, J. & Giraud, G. 1982. La structure hildenbrandioïde, stratégie adaptative chez les Florideés. Phycologia 21:3, 308 - 315. Thanks to Jelte Harnmeijer (http://www.realfuture.org) for translating.
  3. Bertness, M.D. et al. 1983. Snail grazing and the abundance of algal crusts on a sheltered New England rocky beach. Journal of Experimental Marine Biology and Ecology 71:2, pp. 147 - 164.
  4. Dethier, M.N. & Steneck, R.S. 2001. Growth and persistence of diverse intertidal crusts: survival of the slow in a fast-paced world. Marine Ecology Progress Series 223, pp. 89 - 100.