crustose

Lichens: Botanicals Naturalists Overlook

Lichens: Botanicals Naturalists Overlook

“Consider the Lichen. Lichens are just about the hardiest visible organisms on Earth, but the least ambitious.” – Bill Bryson

Lichens are very interesting when it comes to the silent natural world. Instead of being dumb, timeless decoration on rocks and trees, consider this: over the ages this blend of fungus and algae has evolved from scavenging and invading molds, mildews, mushrooms and other…

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From Earth Science Picture Of The Day; April 10, 2015:

Sunburst Lichens on Lake Superior – the Power of Collaboration
Photographer and Summary Author: Rob Sheridan

Lichens are pioneer organisms. They’re the first to colonize bare rock, beginning the rock’s conversion to soil by trapping moisture and enhancing physical and chemical weathering. Lichens are difficult to classify because they’re symbionts, made up of two unrelated species growing in synchrony, compensating for each other’s weakness but forming a much stronger whole. This collaboration brings a fungus together with a photosynthetic single-celled algae or cyanobacterium. The fungus provides structure for both partners while the photosynthesizer provides food for both, converting atmospheric carbon dioxide into glucose and structural molecules. Neither partner can survive without the other, but together they can survive where no other organism can.

Lichens are typically grouped by their gross appearance and color. Crustose lichens have a crusted look, foliose a leafy morphology, and fruticose a branched appearance. The orange colored lichens shown above, Sunburst Lichens (Xanthoria elegans), were found on the basalt rock rimming the north shore of Lake Superior in Minnesota. Most of the surrounding soil and lake sediment owes its formation to rock decomposition initiated by lichens. These slow-growing lichens are among the first organisms capable of inhabiting hostile, nutrient-poor habitats. Their bright color is thought to protect the green algae from excessive ultraviolet exposure. The green lichen is an early successor species, probably Rock-Posy lichen (Rhizoplaca subdiscrepans). Photo taken on August 25, 2014.

Effect of climate change on crustose coralline algae at a temperate vent site, White Island, New Zealand

Originally posted on Ocean acidification:

Natural CO2 vents allow study of the effects of climate change on marine organisms on a different scale from laboratory-based studies. This study outlines a preliminary investigation into the suitability of natural CO2 vents near White Island, Bay of Plenty, New Zealand (37°31.19′S, 117°10.85′E) for climate change research by characterising water chemistry from two vent and three control locations on a seasonal basis, as well as examining their effects on skeletons of the local calcifying crustose coralline algae. pH measurements at vent sites, calculated from dissolved inorganic carbon and alkalinity, showed reduced mean pH levels (7.49 and 7.85) relative to background levels of 8.06, whereas mean temperatures were between 0.0 and 0.4°C above control. Increases in sulfur and mercury at sites near White Island were probably a result of volcanic unrest. Crustose coralline algae did not show significant variability in skeletal Mg-calcite geochemistry, but qualitative comparisons of calcite skeletons under…

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