2. Lytechinus variegatus
• Variegated sea urchin
• Found in the Atlantic
Ocean and Caribbean
Sea
• Generalist grazers
• We hope to determine
feeding behaviors of L.
variegatus before and
after periods of
undernourishment
lookfordiagnosis.com (Beddingfield and McClintock 1997)
(Souza et al. 2008)
4. Chemical Deterrents
• Terpenoid compounds are found in varying
quantities in many different species of algae
• Phlorotannins are specific to brown algae
• These types of chemical defenses are
utilized by algae to protect them against
herbivory
(Hay and Fenical 1987)
5. Experiments
• Experiment #1
o Fed L. variegatus while performing the experimental feeding trials with
algae
• Experiment #2
o Starved L. variegatus for four days and performed the feeding trials
looking for change in feeding behaviors
• Preference Experiment
o The fourth tank during both experiments looked for preference of algae
when all food sources were presented to L. variegatus
6. Hypotheses
• Experiment #1
o H0: L. variegatus will not consume any one genera of algae
more than any other food source provided
o Ha: L. Variegatus will consume more C. verticillata in
comparison to the other food sources provided
• Experiment #2
o H0: Algal consumption will not increase after the starvation of
L. variegatus
o Ha: Algal consumption will increase after the starvation of L.
variegatus
• Preference Tank
o H0: L. variegatus will not favor live rock
o Ha: L. variegatus will favor live rock
7.
8.
9. Weighing Methods
• Algae is laid out and patted
dry to remove a majority of
excess water
• Each algae is weighed to
equivalent amounts before the
experiments
• At the end of the experiments
the algae is siphoned from the
tanks and collected to be
reweighed
• Algae is laid out and patted
dry to remove excess water
• Look for change in weights
10.
11. 0
5
10
15
20
25
30
35
40
45
Brown Red Green All
PercentEaten(%)
Algae Types
Fed
Unfed
Results
Figure 1 shows the average percent algae eaten (±SE) by L.
variegatus during the two experiments: Fed and Unfed
12. 0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Brown Red Green All
Masseaten(grams)
Algae Types
Fed
Unfed
Results
Figure 2 shows the total mass of each alga consumed (±SE)
by L. variegatus during the two experiments: Fed and Unfed
13. • Lytechinus variegatus prefers Caulerpa verticillata
over the other algae presented to it!
• The type of algae that L. variegatus prefers in our
experimental trials indicates what it may eat in its
natural habitat
• There is not a change in feeding in a majority of the
experiments after a period of undernourishment of
L. variegatus
• L. variegatus avoided algae with known
allelochemicals (Dictyota dichotoma)
o Covering behavior (Verling et al. 2008)
14. Hypotheses
• Experiment #1
o H0: L. variegatus will not consume any one genera of algae more
than any other food source provided
o Ha: L. Variegatus will consume more C. verticillata in comparison to
the other food sources provided
o Reject H0
• Experiment #2
o H0: Algal consumption will not increase after the starvation of L.
variegatus
o Ha: Algal consumption will increase after the starvation of L.
variegatus
o Accept H0
• Preference Tank
o H0: L. variegatus will not favor live rock
o Ha: L. variegatus will favor live rock
o Accept H0
15. Future Research
• Souza et al. 2004 experiments looking at two
species of each genera of algae
o These types of experiments are possible and display results
with statistically significant results
o Observed changes in feeding preferences over various
periods of time and how behaviors changed
o Changes in consumption depending on time spent on a
food source
o The pattern of consumption by most popular sources goes
Chlorophyta > Rhodophyta > Phaeophyta
16. Thank you!
• Gretchen Goodbody-Gringley
• Dready
• BIOS
• University of Rhode Island
18. References
• Beddingfield, S.D., McClintock, J.B., (1998) Differential survivorship,
reproduction, growth and nutrient allocation in the regular echinoid
Lytechinus variegatus (Lamarck) fed natural diets. Journal of
Experimental Marine Biology and Ecology 226, 195-215.
• Fong, P., and Paul, V.J., (2011) Coral Reef Algae. Coral Reefs: An Ecosystem in
Transition. 241-272.
• Hay, M.E., Fenical, W., and Gustafson, K., (1987) Chemical Defense Against
Diverse Coral-Reef Herbivores. Ecology 68, 1581-1591.
• Hay, M.E., and Fenical, W., (1988) Marine Plant-Herbivore Interactions: The
Ecology of Chemical Defense. Annual Review of Ecology and
Systematics 19, 111-145.
• Souza, C. F., de Oliveira, A.S., and Pereira, R.C., (2008) Feeding Preference Of
The Sea Urchin Lytechinus variegatus (Lamarck, 1816) On Seaweeds.
Brazilian Journal of Oceanography 56, 239-247
• Verling, E., Crook, A. C. & Barnes, D. K. A. 2004. The dynamics of behavior in
dominant Echinoid populations from American and European West
coasts. Marine Ecology 25, 191-206.
Editor's Notes
Variegated meaning they vary in the color of their spines (Souza et al. 2008)
Found along the east coast of the United States and into the Caribbean (Souza et al. 2008)
Generalist grazers – mean that they will consume what they come across when moving across the reef
In laboratory feeding experiments involving L. variegatus the rate at which the specimens ate varied depending upon the type of algae available (Beddingfield and McClintock 1998)
Have to wonder if they have any way of determining what they want to eat and what they don’t want to eat?..
The three genera of algae provided to L. variegatus were Dictyota dichotoma, Hypnea musciformis, and Caulerpa verticillata
Macroalgae contributes to the bulk of primary productivity in reef communities (Fong and Paul 2011)
Herbivory and grazing has an overwhelming effect on the algal abundance of reef communities in temperate and tropical regions (Hay and Fenical 1988)
Daily grazing of algae is beneficial for their health; however, excessive grazing could pose a threat to the populations of algae
Terpenes found in many different species of algae – alcohol that deters herbivores/predators (not necessarily as toxic as other deterrents)
The percent of terpenoid compound found within the algae
Discuss the difference between palatability (taste) and inhibition of digestion and cell damage
Difference between one type of chemical defense and a combination of chemical defenses working together
Phlorotannins in brown algae specifically (Hay and Fenical 1987)
Explain what happens in each experiment
Why?
Test to see the ecological relationship between algae and L. variegatus
Test to see if there is a change in feeding after a period of undernourishment of L. variegatus
Numerous types of macroalgae contain varying chemical deterrents from herbivores
Talk through the hypotheses in each experiment
Add or take out too much information (too much information on slide now)
Change in algal weight before and after experiment marks consumption or loss from on the sea urchin or from floating out of the tank (error)
The x-axis indicates the genera of algae located in each tank by a common name, which include: D. dichotoma (in the brown tank), H. musciformis (in the red tank), C. verticillata (in the green tank), and all algae and live rock (in the tank labeled “all”)
One-way ANOVA testing showed no significance between each experiment
Large error bars indicating error, which would be algae lost in the experiment not from consumption but from floating out of the tank
However, from our observations and as seen on the graph C. verticillata has the highest percent consumption by L. variegatus
This graph also shows how there was not an increase in feeding in a majority of the experimental tanks after the period of starvation
Again, the x-axis indicates the genera of algae located in each tank by a common name, which include: D. dichotoma (in the brown tank), H. musciformis (in the red tank), C. verticillata (in the green tank), and all algae and live rock (in the tank labeled “all”)
One-way ANOVA testing showed no significance between each experiment
Error bars in this graph indicating some slight variation between before and after weights not by consumption but from not properly drying the algae or enough
However, from our observations and as seen on the graph C. verticillata has the highest total consumption by mass
The “all” tank which held the preference experiment also has a high mass eaten from the both experiments – the algae observed to be eaten most often in that tank was C. verticillata, not the live rock as previously predicted
This graph also shows that there was not an increase in feeding for a majority of the trials after the period of starvation
As noted from our resulting figures and overall observations it appears as though Lytechinus variegatus preferred C. verticillata over other sources of food
This relates back to varying chemical defenses in algae and we look at why L. variegatus chose C. verticillata over the other choices
Hay and Fenical 1988 – discusses the ecology and interactions of sea urchins and other herbivorous grazers with algae that is chemically defended and how that varies between which species of algae it is and what chemical deterrents they utilize
Souza et al. 2008 – Feeding Behaviors of L. variegatus and the recognizable habits when interacting with all types of algae (reactions to chemically defended algae)
Beddingfield and McClintock 1997 – more specifics on how L. variegatus feed on macroalgae based upon availability of the food source
Hay et al. 1987 – focused on the chemical defense of algae and how it acts in defending against herbivores and excessive grazing of the algae
Fong and Paul 2011 – focuses on the importance of macroalgae to reefs in general; important input of energy
Verling et al. 2004 – just defining the covering behavior of sea urchins (don’t need to mention more than on the slide)
Talk through the hypotheses in each experiment
Experiment #1 – Reject H0
Experiment #2 – Accept H0
Preference tank – Accept H0
What could be done in future projects and what I would change
This kind of study is possible and statistically significant results are apparent
Same pattern of preference
