Researching Algae, the Unsung Heroes of Aquatic Food Webs
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 CO2 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 biodiversity, ecology, and distribution of
algae in subtropical wetlands change with hydrology, nutrient
concentrations and habitat. He curates the “Diatom of the month”
blog series aimed to raise awareness on these algae, key primary
producers and indicators of environmental change.
How
did I get to do research on algae? For
my Environmental Science MSc
dissertation project, I worked in the northern Italy’s Alps studying Passerine
bird migration, then my career path took me to office-based research on air
quality and climate change. Wanting to go back to field research, I got a Ph.D.
opportunity at University College London to study the biodiversity and biomass of
microscopic algae in the Okavango Delta, a subject and a place I didn’t know
much about, apart from biology courses and natural science readings. Between
2009 and 2010, I spent ~3 months in Maun (NW Botswana), to carry out the
necessary sampling in this incredible, remote, and near pristine wetland in the
middle of the Kalahari; another ~ 70 months were needed to master and apply
taxonomy and microscope skills, conduct statistical analyses, read, think, and
write my Thesis, as well as working to support my graduate studies.
Fast-forward 8+ years, here I am in
sunny Miami, some 8,000 km away from the cold and misty mountain pass where I
did my MSc research and 12,200 km from the Okavango, to work on another amazing
wetland, the Everglades, as part of a Postdoctoral Associate contract in Dr.
Evelyn’s Gaiser laboratory at Florida International University (FIU). After a
few months at FIU putting together a database for the Comprehensive Everglades
Research Plan Monitoring and Assessment Plan (CERP-MAP) and planning my
publications, I decided, with my postdoc and Ph.D. advisors, to undertake an
ambitious comparative study of patterns and drivers of species richness and
life-history strategies in the Okavango and Everglades. We estimated that, the
Okavango hosts, on average, ~80 species of algae in each sampling site, the
Everglades have ‘only’ ~ 20 (Fig. 2). This is likely due to phosphorus scarcity,
habitat fragmentation due to water diversion schemes, and nutrient pollution in
the Everglades whereas the Okavango is still a near pristine wetland. Moreover,
Florida is a long peninsula, while the Zambezi ecoregion in Africa has been
historically well connected so that organisms may be able to better disperse to
and from this wetland than in the Everglades.
Fig. 2. Map of estimated algal richness and photos from the air: Okavango
(above) and Everglades (below). Okavango (site
averages); UPH= Upper Panhandle; LPH=Lower Panhandle;
XAK=Xakanaxa; BOR=Boro; SAN=Santantadibe.
Everglades; LKO=Lake Okeechobee; LOX=Loxahatchee; Out_ENP=Outside of Everglades
National Park (including the Water Conservation Areas, WCA 2 and 3); ENP=Everglades
National Park.
Although, in
the Okavango, the flooding cycles have a stronger influence on species richness,
as compared to phosphorus in the Everglades, maintaining and restoring the
natural hydrology in these wetlands is critical for the preservation of algal communities,
and thus for the health of food webs. Due to their
outstanding geographic features and biodiversity, both these wetlands are
protected as World Heritage sites, and are
included in the Ramsar Convention on Wetlands of
International Importance, and so
it is critical to keep monitoring these ecosystems.
What’s
next?
I am currently researching how algal
dominance changes with nutrients and hydrology in the Everglades, which is relevant
for freshwater flow and water quality restoration scenarios. I am also trying
to create opportunities for comparative research in other subtropical wetlands.
Last September, I visited the Nanjing Institute of Geography and
Limnology of the Chinese Academy of Sciences and, with other 800 experts, attended
the excellent 10th INTECOL
Wetlands conference in Changshu.
I presented my comparative work and
co-organized a workshop on future directions in wetlands studies, strengthened previous connections
and made new ones with various colleagues working in Asia, South America and
Australia. In June, other FIU scholars and I are planning to present our work
at the next Society of Wetland Scientists’ meeting in Puerto Rico (“Celebrating
Wetland Diversity Across the Landscape: Mountains to Mangroves”), where we aim to foster new
collaborations with ecologists conducting research on wetland ecosystems and
food webs in Central and South America, and beyond. Moreover, Dr.
Gaiser, Dr. Barry H. Rosen (USGS) and I co-organized a special session on how
algae / periphyton mats may respond to different nutrient and hydrology
scenarios in the Everglades for the Greater Everglades Ecosystem Restoration (GEER 2017) conference.
As wetlands are facing unprecedented anthropogenic impacts due to, for example,
land use change, water diversion, and global warming, such collaborations among
scientists, and between us and policy makers, are crucial to foster and inform
sustainable management practices and strong conservation and restoration
activities.
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