Wading Through Research

by Nick Schulte* I think Fragilaria synegrotesca is a cute diatom. Although long and lanky (nothing wrong with that!), F. synegrotesca has an adorable, sometimes very slight, potbelly (Fig. 1).                    Fig. 1 . a)  Live frustules in a rosette colony ( http://fcelter.fiu.edu/data/database/diatom/index.htm?species=3568 )   b) Fragilaria synegrotesca  in valve view (Schulte 2014). Now, some boring diatomist (e.g., me ) might describe that little bump in the middle right as “a unilaterally expanded, hyaline central margin” and that’s accurate enough. But I also like to think of it as F. synegrotesca ’s belly pooch. It brings to my mind the potbellies of seahorses, pigs, puppies and toddlers, and it seems very boop-able. But let’s move past the physical attributes of this diatom, as the allure of this species is in its “actions”. Fragilaria synegrotesca has so far only been reporte...

The Art of Diatoms by Xavier Cortada Artist-in-Residence FIU School of Environment, Art and Society   Fig. 1. Cortada’s one-hundred diatom works on tile (each 6″ x 6″), 2017. I marvel at looking into a microscope.  I focus in and see time. I see the past, really far into the past. I see beautiful small aquatic plants encased in glass that lived on our planet for many millions of years. Sitting inside Dr. Evelyn Gaiser’s Algae Research lab at Florida International University in Miami, I look at a slide   and see diatoms.  Diatoms transport me to a place so distant in time that it wouldn’t look like the Earth I know. They help connect me to an Earth I am trying to better understand. An Earth fluid. An Earth as process. An Earth completely interconnected. An Earth generating life forms across space and time.  Fig. 2 . Xavier Cortada, Drawings of Diatoms from the Everglades, 6″ x 6″, ceramic tile, 2017. In diatoms I also see...

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 int...

by Luca Marazzi* Rhopalodia gibba belongs to the epithemioid group , that is to say it has v alves symmetric about a line (bilateral symmetry), but asymmetrical to the apical (longitudinal) axis, the raphe system is well developed, enclosed within a canal, and positioned near the valve margin 1 . It is longer and more slender than other species such as the lunate R. gibberula , and the more arched R. musculus ; it is found in the benthos, attached to substrata such as plant (epiphytic), or gliding more freely and opportunistically 2 . Interestingly, R. gibba seems to have declined significantly in the United Kingdom due to agricultural intensification and associated large use of nitrogen fertilizers. In fact, t his pennate ( bilaterally symmetric) diatom species lives in nitrogen poor habitats, but it has evolved an endosymbiosis with cyanobacteria that fix nitrogen 3 . So it does not like when there is too much nitrogen around, and loses its competitive edge against other fellow...

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 .         ...