What I Do...Collecting Pieces of the Puzzle

Julianna Brush puts her love for science to work, caring for our water and marine life.

Every year, Julianna Brush and her colleagues conduct an “ecosystem assessment.”  They look at the current health of six watersheds and their aquatic ecosystems along the Chesapeake Bay estuary.  Julianna travels up and down the watershed, observing and collecting samples of water and aquatic life. She then takes the samples back to her lab and conducts molecular biology and toxicology tests.

The data she collects throughout the year, tell us what is going on in each river and how the fish and other  estuarine life are being impacted by human activity and land development along the estuary. 

The purpose of Julianna's work is to monitor the six watersheds, and with what she finds, piece together a puzzle that shows us a "big picture" of the overall health of the ecosystem. 

What are they looking for when doing an ecosystem assessment?

  • Impact of human activities on land use
  • Factors affecting water quality and quantity
  • Ability of habitat to support fish and other aquatic organisms populations (crabs, clams, oysters). 

 

A Day At Work...

  

The QUESTIONS we ANSWER...

  • How do we improve our water quality, protect our wildlife and sustain our population?
  • How is the way we are using our land impacting our aquatic ecosystems?
  • What can we predict about the future based on what we see and know now?

 

In the FIELD with Julianna

Every two weeks we go out out in a 23 ft. center console boat, which also serves as a floating laboratory, to conduct a “community composition survey.” We are looking to see:

  • What species of fish are in the area
  • How many fish of each species and how many blue crabs are in the area
  • Do they have any abnormalities like lesions or tumors, are they healthy 

 

 

The field work can be very physically challenging.  It can be over 90 degrees and terrible heat or freezing rain and you can’t even move your fingers.  It can also be very dirty, muddy and buggy!

On any given day, I can be asked to perform a variety of tasks in the field – anything from collecting water samples, fish larvae, or zooplankton, to assisting with microbiology or marine debris collection.  The great thing about being part of a team is that we help each other out in any capacity, which is a fantastic way to learn about what each of us does, as well as new techniques. 

 

Tools and Techniques

Seining

Seining is a fishing technique used thousands of years ago by the ancient Phoenicians, who used nets to catch fish on the shores of the Mediterranean.  A 100 foot net set is taken into waters up to four feet deep, in kind of horseshoe. One person stands on the beach holding while the other end is taken by another person out into the water, where it is waded upstream against the water current to form a half circle and then returned to shore.  The net collects fish along with some plants and trash.  This technique is very useful, but limits how far out you can go to collect samples.

Trawling

 

 

Trawling allows you to go into much deeper water to collect samples. We use a small fiberglass boat, towing  a benthic otter trawl net behind it (insert photo).  As we move along, the net catches the fish.  You pull the net out of the water and put the fish into a bucket to observe them and look for any abnormalities.  The fish are then returned back to the water. When trawling, the net also captures  crabs and marine debris aka trash which are also part of the ecosystem and evaluated as well.

 

In the LAB

In the lab, we observe the samples we've collected and conduct experiments to gather pieces of data that can be pulled together to create a big picture of the overall health of the watershed.  I use two kinds of science to do this work:

Molecular Biology

Molecular biology is the study of biology at a molecular level. It is concerned with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis as well as learning how these interactions are regulated.

Toxicology

Toxicology combines the elements of biology and chemistry with many other disciplines to help us understand the harmful effects of chemicals on living organisms. Environmental toxicology is the study of the effects of chemicals and other toxins on plants, animals, and the ecosystems in which they live. 

 

Molecular Biology- Quantifying DNA and RNA for Growth Potential

DNA and RNA

 

Some of the lab work we do involves analyzing the DNA and RNA of the fish we bring back from the field.  DNA, (Deoxyribonucleic acid) and RNA, (Ribonucleic Acid), are essential for life and found in the cells of every living organism on earth. DNA is sometimes called the blueprint of life because it holds all of our genetic information and tells everything about who we are.  This genetic information is inherited, passed down from generation to generation and controls the production of proteins, the building blocks of all cells. That means that DNA determines the structure of the cell, whether it will be a nerve cell, bone cell or hair cell etc. 

While DNA acts like the "instruction manual."  RNA is the translator and messenger, de-coding the information into a medium that can be used directly by the cell and then delivering it.  In order to build muscle and to grow you must have RNA, so looking at how much RNA a fish has is a good indicator of healthy the ecosystem is. To find out, we take a muscle sample from a fish and  quantify its DNA and RNA to determine the RNA-DNA ratio or “growth potential.”   If an animal is thriving it will have a high RNA, if it is stressed and at risk, the RNA will be low.  Therefore, RNA/DNA ratios are one way to tell us if  organisms are thriving or stressed.  If we  determine  the growth potential of fish larvae  that will give us an idea of how they will survive in the future so it is a way to help forecast what is coming for that particular population of fish.  If we  determine  the growth potential of fish larvae  that will give us an idea of how they will survive in the future so it is a way to help forecast what is coming for that particular population of fish.


 

Toxicology-Measuring Contaminants in the Habitat

We conduct toxicology experiments to indirectly measure how  contaminants may be affecting aquatic animals. We use the Mummichog as indicator species because its home range is very small, only 50-100ft.  An indicator species is any biological species that defines a trait or characteristic of that particular environment.
Contaminants, such as organophophates, break down quickly in the environment making them difficult and expensive to monitor on a long-term basis.  These chemicals are common pesticides used in house-holds, for agricultural purposes as well as wide-spread mosquito control measures.  To indirectly measure whether these contaminants are present in the water, we  determine  the activity level of an enzyme called acetylcholinesterase in the brain of  the mummichogs.  
How does this tell us if something is wrong?  When you want to move your hand, your brain sends a signal to your hand to start moving and then another to stop. The acetylcholinesterase enzyme is needed to make it possible for you to stop. Think about spraying a bug with a pesticide.  If the bug collapses and begins to twitch, that pesticide that you’ve applied is causing the acetylcholinesterase enzyme to break down and will ultimately lead to the bug’s death if the dose was high enough.  We look at the mummichog for the effects of contaminants because they don't go anywhere with such a small homerange, so if you see a decrease in acetylcholinesterase enzyme activity in a particular area, it can be an indirect indicator of chemical contamination, particularly organophosphate contamination.
We use adult white perch as an indicator of the overall health of the fish in the rivers since they are long-lived, stay in their home river for the most part, and they are recreationally important.  White perch, however, would not be a good indicator species for local contamination because they travel up and down the river, so a decrease in enzyme activity may be caused by several things and you couldn't know where the source of the contamination is.  For the most part, if animals can move when their environment changes to a state that is not conducive to survival, they will move.  
Crabs, for example, will move as the temperature and salinity change.  Striped bass lay their eggs in the Bay and the tributaries each spring and then migrate to the ocean where they overwinter before returning to the tributaries again the following spring to spawn.  This is why we don't use striped bass as an indicator of what's going on in our systems.  So even though they may exhibit signs of disease or stress, we are unable to relate it back to land-use because we don't know where the stressor exists - could be anywhere that they travel.  
 

Choosing and Indicator Species 

The choice of the correct indicator species is an important and will depend on what question you are asking.  Striped bass lay their eggs in the Bay and the tributaries each spring and then migrate to the ocean where they overwinter before returning to the tributaries again the following spring to spawn. This is why we don't use striped bass as an indicator of what's going on in our systems.  Even though they may exhibit signs of disease or stress, we are unable to relate it back to land-use because we don't know where the stressor exists - could be anywhere that they travel.