Re: How have changes in the enviroment (ex. climate change) impacted Protists?

Dear Laura
I am extremely sorry for such delayed reply..
Your question really got me to think and since the research field that I am working (Biology of 
Corals) is also influenced by protists (dinoflagellates that form symbiotic relationship with 
corals), I thought I should spend more time in looking for the answer as well as thinking....
Although what I have presented here is not all, it is at least part of the picture and I hope this will 
help your quest and work.

Protists, are a diverse group of eukaryotic microorganisms. Historically, protists were treated as 
the kingdom Protista but this group is no longer recognized in modern taxonomy. Instead, it is 
"better regarded as a loose grouping of 30 or 40 disparate phyla with diverse combinations of 
trophic modes, mechanisms of motility, cell coverings and life cycles.  Currently, the term protist 
is used to refer to unicellular eukaryotes that either exist as independent cells, or if they occur in 
colonies, do not show differentiation into tissues. The term protozoa is used to refer to 
heterotrophic species of protists that do not form filaments.
Some protists are significant pathogens of both animals and plants. For example Plasmodium 
falciparum which causes malaria in humans and Phytophthora infestans which causes potato 
blight. A more thorough understanding of protist biology may allow these diseases to be treated 
more effectively.

Protists have scarcely been considered in traditional perspectives and strategies in environmental 
management and biodiversity conservation. This is a remarkable omis- sion given that these tiny 
organisms are highly diverse, and have performed as key ecolog- ical players in evolutionary 
theatres for over a billion years of Earth history. Protists hold key roles in nearly all ecosystems, 
notably as participants in fluxes of energy and matter through foodwebs that centre on their 
predation on microbes. In spite of this, they have been largely ignored in conservation issues due 
to a widespread, naive belief that protists are ubiquitous and cosmopolitanously distributed. 
Nevertheless, recent research shows that many protists have markedly restricted distributions. 
These range from palaeoendemics (Gondwanan-Laurasian distribution) to local endemics. Our 
ignorance about the ultimate and proximate causes of such acute disparities in scale-dependent 
distributions of protists can be tagged as a singular reason to preserve these more cryptic 
participants in ecological and evolutionary dynamics. This argument is disturbing when one 
considers anthropogenic modifications of landscapes and the very poorly understood roles of 
protists in ecological processes in soils, not least in agroecolandscapes and hydrological 
systems. Major con- cerns include host specific symbiotic, symphoric and parasitic species which 
becomeextinct, unseen and largely unknown, alongside their metazoan hosts; change or loss of 
habitats; massive change or loss of type localities; and losses of unique genetic resources and 
evolutionary potential.

Disturbance and loss of habitats threaten not only plants and animals, but also protists which are 
sensitive indicators of environmental changes. Of special concern is the devastation and loss of 
rain forests, where many groups of protists are heavily under-researched, both in limnetic and 
terrestrial habitats. This deficiency becomes obvious when one looks at the earth’s biodiversity 
hot- spots, where 44% of all species of vascular plants and 35% of species in four vertebrate 
groups (birds, reptiles, amphibians, mammals) are found: most hotspots are rain forests in the 
tropics and subtropics. This  further highlights our drastic ignorance of protist diversity and 
biogeography. With the partial exception of the Mediterranean Basin, no or very sparse data are 
available on ciliates and many other protist groups from these hotspots.
Moreover, protist type localities are not only threatened by such local destruction of habitats, but 
also by massive environmental changes. A pertinent example is the testate amoeba Difflugia 
biwae, a supposed local endemic of Lake Biwa in Japan. It was discov- ered in 1918 but 
disappeared in the 1980s, likely due to the heavy eutrophication of the lake. 

Climate change is also effecting the presence of protists.  Pathogens that cause malaria or 
disease in vegetables that belong to protist as a result of altered environment could be seen 
more frequently in many parts of the world in which at present they are not seen since such 
pathogens require hotter climates, hence if there is global warming and things get hotter in 
those part of the world such as high latitudes, we could find occurrences of such protist 
mediated infections and diseases more frequently.
Also, one other protists which is of my interest are the dinoflagellates (commonly known as 
zooxanthellae and belong to Symbiodinium sp.) living inside the tissue of corals forming a 
symbiotic relationship and responsible for coral growth and metabolism in turn giving rise to 
those beautiful coral reefs in the tropical ocean waters.  The symbiotic relationship in part 
depends on the presence of stress tolerant zooxanthellae. If due to climate change, global 
warming and other stress, this symbiotic relationship is harmed then corals undergo what is 
know as bleaching which is partly due to loss of the zooxanthellae which are nothing but 
protists. And loss of coral reefs could cause major problem for coastal nations which are highly 
dependent on these coral reefs for tourism, livelihood and also protection of islands.

Hence, Protists are very important and are often ignored in terms of research and conservation.

I hope this answers your question

Best
Shahsank


References: 
I have copied part of this write-up from a recently published book titled," Protist diversity and 
geographical distribution" and the chapter,"Conservation of Protists, is it needed at all? by 
Cotterill et al. 2009, Springer DOI: 10.1007/978-90-481-2801-3_15
The same article was originally published Originally published in the Journal Biodiversity and 
Conservation, Volume 17, No 2, 427–443. DOI: 10.1007/s10531-007-9261-8 © Springer 
Science+Business Media B.V. 2007.

Other references: http://en.wikipedia.org/wiki/Protist