Deepesh R Bista
Effects of Increased Temperature and Nitrogen on Non-N-Fixing
vs. N- fixing Cyanobacteria in Western Lake Erie: Implications
for Competition, Herbivory and Climate change.
Introduction and background:
Climate change has been a topic that everyone is talking of lately, some go deep in to it and
some just go surface. Its strong association with the algal blooms (esp. Cyanobacteria) is one
of many issues regarding climate change.

Climate change: Climate change refers to any significant change in measures of
climate (such as temperature, precipitation, or wind) lasting for an extended period
(decades or longer). Climate change may result from natural or human factors.
EPA.GOV
Introduction:
Cyanos are increasing problem:
 In the current century, global mean temperatures are expected to increase an
additional 2–50C (Houghton et al., 2001) and in this context cyanobacterial bloom
formation is hypothesized to increase even more (Mooij et al. 2005; Jeppesen et al.
2007).
 Cyanobacterial blooms are expanding globally and now threatening the ecological
integrity and sustainability of some of the world's largest and most resourceful water
bodies, including Lake Victoria, Africa; Erie, US– Canada; Okeechobee, Florida,
USA (Havens et al., 2001); Taihu, China (Qin et al., 2010); the Baltic Sea in
Northern Europe (Conley et al., 2009a); and the Caspian Sea in West Asia (Paerl and
Huisman, 2008).

Harmful algal bloom: This is an algal bloom that causes negative impacts to other
organisms via production of natural toxins, competition, abundant growth leading to
mechanical damage to other organisms, or by other means. Cyanobacteria often cause
this kind of bloom.
Causes of Blooms
Cyanobacterial blooms are the result of complex and synergistic environmental factors
rather than a single dominant variable (Hyenstrand et al. 1998; Dokulil and Teubner
2000).
Deepesh R Bista
o
Temperature:
 As temperature increased, the algal group with the highest growth rate
changed from diatoms to green algae to blue-green algae
(cyanobacteria) (Canale, R. P., and A. H. Vogel. 1974. E).
 Increased temperature due to global warming is predicted to increase
cyanobacterial blooms because of increased water temperature, the longer
period of thermal stratification, and increased internal nutrient loads,
all of which are beneficial to cyanobacteria (Jo¨hnk et al. 2008; Paerl
and Huisman 2008; Wilhelm and Adrian 2008).
 Western Lake Erie has seen its temperature increasing in recent years
with record-breaking temperatures, along with the increasing HAB’s.
o
Nutrients:
 Even though phosphorus (P) is supposed to be the limiting nutrient,
nitrogen (N) may be equally important in the occurrence of toxic nonN-fixing cyanobacteria blooms, such as Microcystis sp. Laboratory
studies have indicated that increasing N loads increase the growth and
toxicity of this species (Watanabe and Oishi, 1985; Orr and Jones,
1998; Codd and Poon, 1988).
 Moreover, laboratory research suggests toxic strains of Microcystis are
able to outgrow non-toxic strains at high nitrogen levels (Ve´ zie et al.,
2002).
Gaps in Research:
Many studies have been done with cyanobacteria regarding temperature increases and higher
nutrient loads but very few have shown the relationship of this increase and load to toxin
production and then its effect on the zooplankton (herbivory) and the competition between
the N-fixers and non- N-fixing cyanobacteria.

Nitrogen Fixation: Conversion of atmospheric nitrogen gas into organic nitrogen or
to forms, readily utilized in biological processes useful to plants and other organisms
by lightning, bacterial-induced nodules, and blue-green algae. This is part of the
nitrogen cycle.
Deepesh R Bista
My purposed RESEARCH:
The overarching objective of my proposed research is to investigate how global warming and
eutrophication will influence the timing, extent and species composition of cyanobacterial
HABs in temperate freshwater lakes.
In most summers, we get a bloom of Microcystis and a second bloom of a nitrogen-fixing
species (either Anabaena or Aphanizomenon) under low N conditions in late summer. If in
the future temperature and nitrogen increase, then what will happen to this succession of
bacterial blooms? How much the competition will have its say and what does the community
looks like are some of the things I will be trying get answer of.
1. Investigate how increase in water temperature and N, individually and in
combination, affect the growth, toxicity and herbivore food quality of important nonN fixing and N-fixing Lake Erie CyanoHABs.
2. Determine how water temperature and N affect competition between important nonN-fixing and N-fixing Lake Erie CyanoHABs.
3. Determine how water temperature and N affect herbivory of important non-N-fixing
and N-fixing Lake Erie CyanoHABs.
4. Using 1-3 results I will try to generate a model to predict effect of temperature and N
on CyanoHABs in Lake Erie, including relative success of non-N-fixing and N-fixing
CyanoHABs in the future, when lake temperature are warmer, growing seasons are
longer and N levels are likely to be higher.
References:
-
-
-
-
Tillmanns, Angeline R.; Wilson, Alan E.; Pick, Frances R.; Sarnelle, Orlando (2008)
Meta-analysis of cyanobacterial effects on zooplankton population growth rate:
species-specific responses. Fundamental and Applied Limnology 171: 285-295.
Claska ME, Gilbert JJ (1998). The effect of temperature on the response of Daphnia
to toxic cyanobacteria. Freshw Biol 39:221–232.
Davis, T. W. and C. J. Gobler (2011). "Grazing by mesozooplankton and
microzooplankton on toxic and non-toxic strains of Microcystis in the Transquaking
River, a tributary of Chesapeake Bay." Journal of Plankton Research 33(3): 415-430.
Song L.; Sano, T.; Li, R.; Makoto, W.M.; Liu, Y.D.; Kaya. K.; (1998). Microcystin
production of Microcystis viridis (cyanobacteria) under different culture conditions.
(1998). Phycology Research, 42:19–23.
Timothy W. Davis, Dianna L. Berry, Gregory L. Boyer, Christopher J. Gobler (2009).
The effects of temperature and nutrients on the growth and dynamics of toxic and
non-toxic strains of Microcystis during cyanobacteria blooms. Harmful Algae 8:715725.