Last year (2015), I had the pleasure of performing field work in Nome, Alaska with a professor named Dr. Derek Taylor. Dr. Taylor had devised a brilliant set of experiments to study animals local to the tundras of Alaska. We arrived at the end of July and stayed for approximately one week. While there, we witnessed environments unscathed by the touch of man. We beheld landscapes that seemed as though they were painted into existence, holding beasts of great magnificence and power. We heard muskoxen snort in discontent, warning that we were too close.
(Click Picture to Enlarge
-Photo taken by Mr. Bill Nichols of the University at Buffalo)
Despite all of the obvious wonders around us, we were there for something else entirely. Global climate change shifts aquatic ecosystems as the borders of bodies of water are altered rapidly. This is especially so for freshwater environments. These environments are the homes to a number of zooplankton* species.
(Click Picture to Enlarge
-Left – Daphnia, Top Right – Heterocope, Bottom Right – Chaoborus)
While in Alaska, we collected zooplankton samples from a variety of locations. The samples were gathered from numerous freshwater sources using D-nets or throw-nets depending on the depth of the water. D-nets are attached to a long wooden handle, whereas throw nets are thrown and then reeled back in, allowing the net to catch these tiny organisms as it passes. Samples were generally preserved using ethanol solutions or by drying them out. They would later be kept in freezers to maintain the integrity of their nucleotide sequences (see previous post – April 19th, 2016).
Dr. Taylor once told me that despite their small size, if one were to only consider the mass of zooplankton on our planet, the outlines of all of the major bodies of water would still be visible from space. This thought is truly astonishing and goes to show that there is an entire world of organisms that most people do not even consider.
These zooplankton are also a major component of the freshwater and saltwater ecosystems that they reside in. They can range from keystone predators to primary consumers that simply eat the algae in these waters. They are a major food source to countless organisms as they play their role in the food web.
Taking this a step further, there are viruses that are specifically adapted to infect individual species of zooplankton. These viruses can be extremely diverse and found in most (or all) types of zooplankton. Their tremendous numbers and quickly changing DNA makes them difficult, yet interesting to study. One method of doing so is known as metagenomics.
For a metagenomic analysis, a researcher sequences all of the genetic material in a given sample. In this case, it would be everything within a certain volume of water. This type of analysis then requires the researcher to take all of this data and compare it to known databases in order to find out which segments of DNA or RNA* are coming from which organisms (some viruses store their genetic information in the form of the molecule RNA, instead of DNA). This can be tricky since certain viruses are so new and underrepresented that they do not share high sequence similarity to anything in public databases. In our samples, I rarely saw viral segments of DNA/RNA that matched with known viruses to a degree of greater than 70%.
These zooplankton and their viruses have a massive impact on a number of organisms in their food webs. In this area of research, there are interesting stories around every corner. One just needs to ask the right questions.
Plankton – The aggregate of passively floating, drifting, or somewhat motile organisms occurring in a body of water, primarily comprising microscopic algae and protozoa
Zooplankton – The aggregate of animal or animal-like organisms in plankton, as protozoans
RNA – Acronym for Ribonucleic Acid – any of a class of single-stranded molecules transcribed from DNA in the cell nucleus or in the mitochondrion or chloroplast, containing along the strand a linear sequence of nucleotide bases that is complementary to the DNA strand from which it is transcribed: the composition of the RNA molecule is identical with that of DNA except for the substitution of the sugar ribose for deoxyribose and the substitution of the nucleotide base uracil for thymine.
Definitions from Dictionary.com
There are more pictures of our trip to Alaska in the Photography section of this blog.