debor042

by Luca Marazzi * Why is it important to study algae? To start with, algae produce ~ 50% of the oxygen on planet Earth, they are food for small and large animals that in turn are eaten by people, but they also recycle nutrients and absorb CO 2 from the air; by existing and doing their own thing, these microorganisms provide these so called ecosystem services to human beings (Fig. 1). Moreover, as algae reproduce fast and are often adapted to specific environmental conditions, understanding how many species of algae, and which ones, live where and why give us cues as to the health of aquatic ecosystems, such as rivers, lakes, and wetlands.  Fig. 1 . Simplified scheme of the role of algae in food webs (from my Ph.D.  Thesis ). * Dr.   Luca Marazzi   is a freshwater ecologist working in   Dr. Evelyn Gaiser’s research group   in the School of Environment, Arts and Society at Florida International University. His main interest is how biodive...

by Luca Marazzi* ‘Who’ is it and where does it live? This diatom is monoraphid, that is to say it has a raphe only on one valve, as shown in the figures. Monoraphid species are one of 9 major morphological types of diatoms - the other ones are: centric (like Cyclotella meneghiniana ) , araphid (e.g. Asterionella formosa , which forms star-shaped colonies !), eunotioid (e.g. the beautifully ornamented Eunotia diadema ), symmetrical biraphid (e.g. the slender Navicula lanceolata ), asymmetrical biraphid (e.g. Gomphonema parvulum ), epithemioid (e.g. Rhopalodia gibba , which hosts nitrogen-fixing bacteria as symbionts), nitzschioid (e.g. the organic pollution-loving Nitzschia palea ), and surirelloid (the big Surirella ovalis ) 1 . Like in many other cases, the taxonomy is far from settled though; following recent research, numerous specimens usually named C. placentula should be more accurately named Cocconeis lineata and C. euglypta 2 .             ...

I admit that I ended that last post a bit unclear. But diatoms, it should be said, aren’t (or, rather, shouldn't be said since I shouldn't use double negatives. Ah, well.). Not physically, that is; you see, diatom cell walls are made of silica (glass), and that feature is actually incredibly important (not to mention gives rise to beautiful 'micromanipulations' like this one by Klaus Kemp - different colors in part because of different thicknesses of their glass). Diatoms arose between 180 and 225 million years ago – youngsters in the algal world (compare that to the geezer cyanobacteria of 3+ billion – way vintage) – and in so doing utilized an under-used, widely available resource that set them apart. The genealogy (or “systematics”) of diatoms has since expanded to include anywhere from 20,000 to over 1 million species that span almost every aquatic or semi-aquatic habitat imaginable – oceans, lakes, rivers, moss, soil. In those habitats they can be suspended in ...

This post was written by Nick Schulte, a Master's student in Evelyn Gaiser's lab at Florida International University.  So where would you go to study how Everglades algae respond to increased nutrients from sea level rise? The Florida Everglades, right? That’s what I thought. But I went to Iowa. Iowa Lakeside Laboratory , more specifically, on the shores of Lake Oko boji (yes, I still confuse it with that big lake in the northern ‘Glades). A bit clearer but still unhelpful? This summer I attended two courses at Lakeside: Ecology and Systematics of Diatoms and Ecology and Systematics of Freshwater Algae. In that order – specific to general, that’s how it’s normally done, right? Start looking at the fineries of a specific group of algae (“the algae that live in glass houses”, or diatoms) and then see how they fit into the bigger picture of general phycology (“phykos” for “seaweed”). It actually makes a lot sense, especially when my research pays particular attention to the cha...