The Effect of Nutrients on the Propagation and Growth of Potamogeton Perfoliatus (Redhead Grass)

Abstract

In this project the effects of nutrients on the growth of a specific species of Submerged Aquatic Vegetation (Potamogeton perfoliatus) will be studied. This study is relevant to the state of Maryland and to groups such as DNR (Department of Natural Resources). Since the middle of the last century the quantity of Submerged Aquatic Vegetation (SAV) beds have decreased. Groups are researching the cause of this decline and trying to prevent this from happening in the future. If SAV are healthier with the addition of nutrients, then the scientists growing SAV in laboratories might consider adding similar nutrients to the sediment, on condition that that it does not disturb the experiment.

This project has three sections. The first section is, the effect of infusing nutrients into the sediment on growth of SAV. The second section is, does the addition of nutrients affect water quality. The third section is, the growth rate of Potamogeton perfoliatus. These sections shall be referred to as Problem 1, Problem 2, Problem 3, in the order mentioned. 

In Problem 1, six trays of Potamogeton perfoliatus were planted, 12 plants were in each tray. The trays alternated green and red; green had Miracle Grow sticks added for nutrients and red had no nutrients. All of the plants were measured once a week. This process was completed three times; the first trial was done to ensure that this species could be grown under a laboratory environment, the second trial was performed and only the longest shoot of each plant was measured, in the third trial all shoots were measured.

Written resources and DNR sources state that Potamogeton perfoliatus with added nutrients will grow faster because Miracle Grow contains eight of the fourteen essential nutrients, but for statistical purposes I propose the Null hypothesis. I will accept the Null hypothesis unless I can achieve a 95% confident level through a T-test. 

In Problem 1, the T- test showed 90%. Which is below 95%, so I cannot reject the Null hypothesis. The T-test value was so low because the standard deviations were so high which indicates a wide range of data. 

In Problem 2, two separate trays were created; neither tray had plants. One of the trays had nutrients (Miracle Grow sticks) added to it, and the other did not. This was done to determine if the nutrients dissolved into the water or remained in the sediment. In Problem 1 trays with nutrients and without nutrients were in the same tank.

I predict that the addition of Miracle Grow sticks will only affect the nitrate level because Miracle Grow contains ‘water soluble nitrogen’ which should dissolve in water if not used by a plant. Miracle Grow does not contain lime or sodium, which raise the pH and salinity levels. 

This hypothesis is correct, only the nitrate level did increase, from 0 ppm to 15 ppm. This is due to the fact that some of the nitrogen was water-soluble. 

In Problem 3, the data from the first section was analyzed and it was determined how much each plant grew in a week, regardless of nutrients. Then these numbers were averaged and graphed. 

I predict that the plants will grow very little at first, because when plants are propagated they have no roots, so all of the nutrients will be focused on recreating roots. Then the plants will grow rapidly, and then they will slow down and continue at a steady pace. 

I reject this hypothesis because the growth did not ever slow down. They grew very little the second week, 2 cm, but grew almost 11 cm during the next week. There was not a point in the data where the growth slowed down.

Problem

1. What is the effect of infusing nutrients into the sediment on Potamogeton perfoliatus (Redhead Grass) propagation and growth?
2. How does the addition of nutrients to the sediment affect the water quality?
3. What is the rate of growth for Potamogeton perfoliatus?

General Submerged Aquatic Vegetation Information

• Abbreviated to SAV
• Improve health of the Chesapeake Bay
• Can survive in all salinity levels
• Live in Chesapeake Bay and its tributaries
• Declining in Chesapeake Bay and its tributaries
• Need light, phosphorus, and nitrogen
• Many types live in the Chesapeake Bay- both native and invasive species
• Food for wildfowl
• Habitat for marine mammals

Types of SAV Commonly Found in the Chesapeake Bay

Water Quality and SAV Decline

These two factors create a dust bowl effect and without one the other is not balanced. SAV reduce turbidity levels by anchoring the topsoil with their roots and keeping it from washing away. When the SAV dies back the rich topsoil floats in to the water and therefore increases the turbidity. When turbidity increases continually in a body of water, the SAV cannot carryout photosynthesis to live, and the cycle starts over. As plants, SAV use nitrogen and phosphorus to grow, and there is less in the water. When the SAV die back there is more nitrogen and phosphorus in the water for algae to bloom in excessive amounts. When algae blooms occur the turbidity also decreases, which kill the SAV, thereby allowing nutrients to build up and the cycle starts again.