corrected nematode poster 40x32
TRANSCRIPT
The Effect of Lawn Treatment on Nematode Diversity Around Lewis & Clark College
By Bobby Brandt ‘16 and Melanie Morris ‘15 INTRODUCTION
METHODS
RESULTS DISCUSSION
REFERENCES
ACKNOWLEDGEMENTS
Healthy ground soil is essenGal to providing ecosystems with a with a firm base for maintaining the wellbeing of plants and animals1. The health of the soil is deeply interconnected with the acGvity of detriGvores, organisms that break down waste in the environment, and their predators. Both groups contain a wide range of diversity that fulfill various roles to maintain soil health. These organisms are sensiGve to soil condiGons, and any adjustments in the condiGons can cause changes in both populaGons. With the expansion of human land development, soil condiGons are rapidly changing, and could be puOng soil invertebrate populaGons in jeopardy1. However, we can use soil invertebrate diversity as a bioindicator for our impact on soil health2. The diversity of oil nematodes, the predators of many detriGvores, has been idenGfied as being integral to soil health3. Soil nematodes are parGcularly good candidates to be used as bioindicators for human impact on soil health for the following reasons: • They are abundant worldwide • They are widely diverse • They are relaGvely easy to collect • They are highly sensiGve to changes in soil
In this study, we aUempt to show the impact of human lawn treatments around Lewis & Clark College on soil nematode diversity, and we present a working method for future nematode collecGons.
HYPOTHESIS We predict that there will be more nematode diversity in the forest areas than the treated lawn areas because the soil condiGons in the forest are assumed to be less affected by human chemical treatments2 and plant diversity is less homogenous than on the lawn.
We would like to thank Dr. Greta Binford, Dr. Greg Hermann, and Dr. Michael Ailion for their advice and support for this project. We would also like to thank the Hermann lab for sharing worm maintenance materials and E. coli plates. Finally, we would like to thank the Lewis & Clark Biology Department for providing the resources that made this project possible.
1.Doran, J. and Zeiss, M. 2000. Soil health and sustainability: managing the bioGc component of soil quality. Applied Soil Ecology. 15(1): 3-‐11 2. Yeates, G. and Bongers, T. 1999. Nematode Diversity in Agroecosystems. Agriculture, Ecosystems & Environment 74(1): 113-‐35. 3. EUema, C. 1998. Soil Nematode Diversity: Species Coexistence and Ecosystem FuncGon. Journal of Nematology. 30(2):159-‐169. 4. De Ley, P. “A quick tour of nematode diversity and the backbone of nematode phylogeny”.January 25, 2006, WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.41.1, hUp://www.wormbook.org. Web. 4 October 2014. 5. Barrière A., Félix M. A. “IsolaGon of C. elegans and related nematodes”. May 2, 2014. WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.115.2, hUp://www.wormbook.org. Web. 4 October 2014.
FUTURE DIRECTIONS
We tried many methods for nematode collecGon using old fruit (Table 1). However, some fruits proved to be more effecGve for nematode collecGons than others. Apples disintegrated too quickly to be recovered, and nematodes could not be collected from grape samples. The best fruit seems to be the banana, as nematodes will colonize in the peel and the peel does not disintegrate and is likely less palatable to local wildlife.
Table 1: Results from fruit methods for collecOng soil nematodes.
Examples of IdenOfied Nematodes
Figure 2. Diplogastrid idenOfied by mouthparts from the forest area.
Figure 3. RhabdaOs idenOfied by mouth parts from the lawn area.
Nematode CollecOon Fruit Method: Chunks of fruit were buried approximately 1.5cm under soil in either the Lewis & Clark College Forest or on a treated lawn area with exposed soil. The samples were lel six to twelve days and then collected. The fruit was put on a bacteria lawn of E. coli and the nematodes were allowed one hour to crawl onto the plate. Soil Method: Approximately one tablespoon of soil was scaUered on an E. coli lawn and moistened5. Nematodes that crawled onto the lawn within 24 hours were collected. Nematode Maintenance Nematodes were kept at room temperature and “chunked” onto new plates when old one became crowded (every 2-‐3 days) Adult nematodes were picked onto an agar pad and suspended in a soluGon of levamisole to immobilize them, and they were imaged using AxioImager at 100x zoom. We compared the images and characterisGcs to known organisms classified in the WormBook4,5.
MounOng Specimens and Imaging
IdenOfying Nematodes
Fruit Number of Samples in Forest
Number of Samples on
Lawn ProtecGon Days Lel
on Soil Sample
Recovered Nematodes
Found Nematode Eggs
Found
Grape 3 3 Buried only 7 Yes None None
Apple 4 4 Petri dish cover and buried 7 No N/A N/A
Apple 1 1 Buried only 12 No N/A N/A Banana 1 1 Buried only 12 Yes Yes Yes
Banana 1 1 Buried only 12 No N/A N/A
Banana 1 1 Cup cover and buried 6 Yes Yes None
We have provided a starGng point for many future experiments that wish to look at nematode diversity and abundance as a bioindicator for soil health. Future experiments should consider the following: • Increase sample size and Gme of collecGons • Include non-‐bacteria feeding nematodes • Increase of soil collecGon by taking soil cores • Measure soil condiGons including:
o pH o Moisture o Mineral content
• Refine taxonomic classificaGon by using molecular data
We expect groups that take these future direcGons into consideraGon will gain greater insight on human impact on soil condiGons around Lewis & Clark College.
IllustraGon from Barrière, 20145
IllustraGon from Barrière, 20145
Family LocaGon Method of CollecGon
Number of Nematodes Collected
Number of Egg Clusters Collected
Rhabditae Subfamily: Diplogastrid
Rhabditae Forest Banana 6 Days 1 0
Rhabditae Forest Soil 1 0
Rhabditae Lawn Banana 12 Days 1 1
Rhabditae Lawn Banana 6 Days 1 0
Rhabditae Lawn Soil 1 0
Table 2: Nematodes collected from the different locaOons idenOfied to the family level. There is no significant difference in the diversity or abundance of nematodes between the two areas.
Nematode Diversity We imaged and idenGfied all collected nematodes to the family level, which was the highest taxonomic resoluGon possible. Molecular analysis would need to be done for further resoluGon. A comparison between the number of families found between the forest and lawn locaGons shows that there is no significant difference in nematode diversity, as all specimens are in the Rhabditae family (Table 2). Because one nematode specimen was collected from each type of sampling at each locaGon, there is also no significant difference between the abundance of nematodes in either locaGon.
The goal of this study was to use nematode diversity as a bioindicator for soil health around Lewis & Clark College. We hypothesized that we would find more nematode diversity, in the form of a greater number of families, present in our forest samples when compared to the lawn samples. However, our preliminary data suggest that there is no significant difference between the diversity of nematodes in either condiGon, as only one family could be idenGfied from all of the samples. Molecular analysis would refine the taxonomic resoluGon and indicate show differences in nematode diversity that we cannot idenGfy now. Although our data do not show significant differences, it is important to conGnue working on valid methods to monitor human impact on soil invertebrate diversity. The work of soil invertebrates, including nematodes, improves the quality of the soil and supports healthy ecosystems, making a healthier planet. It is therefore important that we monitor our impact on soil invertebrates, so we do not end up harming the rest of the world.
Forest Banana 12 Days 1 0
Family Location Method of Collection Number of Nematodes Collected
Number of Egg Clusters
Collected
Rhabditae Subfamily: Diplogastrid Rhabditae Forest Banana 6 Days 1 0
Rhabditae Forest Soil 1 0 Rhabditae Lawn Banana 12 Days 1 1
Rhabditae Lawn Banana 6 Days 1 0
Rhabditae Lawn Soil 1 0
Forest Banana 12 Days 1 0