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Conclusion
Reproductive Characteristics of Invasive Lionfish in Bermuda Jennifer Salas, Corey Eddy, and Diego Bernal
Department of Biology, University of Massachusetts, Dartmouth, MA Contact Information: Twitter: @salas_jenn24, Email:[email protected]
Methods
Results • Lionfish (Pterois miles and P. volitans) are native to the
Indo-Pacific oceans and have been recently reported in the Western Atlantic (WA) Ocean from Brazil to North Carolina.
• This study focuses on lionfish in Bermuda. Bermuda was one of the first places outside of the United States to be invaded by lionfish but it has the smallest lionfish population.
• Lionfish in the WA have a broad diet, occupy anywhere from 20m to 80m, 10oC to 30oC and appear to have no natural predators. (Kimball 2004)
• In the WA, lionfish appear to spawn all year, have large quantities of eggs at one time, however their frequencies of spawning are unknown. GSI = 1E-06(TL2.4703)
R² = 0.16758
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• Seasonal spawning appears to happen through out the year when the water is warmer then potentially more lionfish are actively spawning.
• In the winter months they tend to be resting in the developing stage.
Figure 4: GSI and the TL of the fish. The circles in red and blue have already spawned. Sample size= 62 fish.
Figure 3: TL and body mass comparison. Black line represents the regression line of Bermuda, purple line is Little Cayman (Gardner 2015). Sample size= 62 fish.
Figure 6: June through September data of spawning ability and depth fish were caught at. Numbers on top of column represent sample size.
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Discussion • Body mass and total length of Bermuda lionfish
appear to be similar to Little Cayman. The fish that are longer and have a higher body mass are fish that have just spawned and are now resting.
• Higher GSIs were observed during the months lionfish were spawning the most because the ovaries are potentially bigger which makes the overall body mass higher. There are no data from other studies comparing GSI to the length of the fish. However, Gardner observed higher GSIs when they were the most reproductively active (Gardner 2015). Even though the lionfish are not spawning year round, when they do spawn their GSIs are higher like Gardner 2015.
• Lionfish in Bermuda appear to be seasonal spawners, unlike Little Cayman. However, there is a sign that they are developing year ‘round. The most spawning happens during June through September when the water is the warmest.
• This graph shows that Lionfish are only actively spawning in 45m to 65m. November through May dates are not shown because we did not catch any fish that were in water deeper then 25m. Also, there are no data of other studies comparing depth and maturity in ovaries. Lionfish have been observed in deeper water but the research of why they are there is unknown.
Figure 2: Development stage of the eggs in the ovaries. These are either immature (primary growth, PG), developing (cortical alveoli, CA, primary vitellogenic, VTG1 or secondary vitellogenic, VTG2), spawning capable (tertiary vitellogenic, VTG3), actively spawning (hydration, H, germinal vesicle migration, GVM).
Acknowledgements • Special thanks to Ken Oliveira, for letting us use his
equipment and Mass Histology for preparing most of our slides.
• This research was supported by the National Science Foundation research experiences for undergraduates.
Objective
Background
• This study quantifies the reproductive biology of lionfish in Bermuda.
• This study also looks at if Bermuda is significantly different from other WA regions, specifically looking at the gonadosomatic indices (GSI), degree of egg development throughout the year, and determined if there are seasonal spawning events of lionfish.
• Female lionfish were collected off Bermuda from 2013 to 2016, TL, body mass were measured, and calculated by the total ovary mass divided by the total fish mass and multiplied by 100 which is determined by the GSI.
• The ovaries were weighed and cross sectioned at the midpoint (Figure 1C).
• Ovary sections were dehydrated, embedded with wax, cut into 5ųm and stained using as Hematoxylin and Eosin.
• Fixed and stained sections were viewed under a microscope to 4x and the developmental stages were identified. (Figure 2)
• Analysis of the developmental stage of the ovaries was determined with correlation to the TL, ovary mass, body mass, and depth of capture.
2
Figure 1: (A) Map of Bermuda (B) Representative mature female lionfish, TL= total length (C) insert shows overall location of the ovaries. Insert grey area pictured shows a mature ovary.
B CBlue line: Where ovaries are sectioned.
Developing
Actively Spawning
Immature
Spawning Capable
Slide with cross sectioned ovary. Darling, Emily S., et al. "Indo-Pacific lionfish are larger and more abundant on invaded reefs: a comparison of Kenyan and Bahamian lionfish populations." Biol Invasions, 17 May 2011.
Eddy, Corey, et al. Unpublished data. Gardner, Patrick G., et al. "Reproductive Biology of Invasive Lionfish (Pterois spp.)." Frontiers in Marine Science, 30 Jan. 2015. Kimball, Matthew E., et al. "Thermal tolerance and potential distribution of invasive lionfish (Pterois volitans/miles complex) on the east coast of the United States." MARINE ECOLOGY PROGRESS SERIES, PDF ed., Nov. 2004. Morris, James A., Jr., et al. "Oogenesis and spawn formation in the invasive lionfish, Pterois miles and Pterois volitans." Scientia Marina, Mar. 2011. Paisano. "Lionfish." Caribe Sunset, www.caribesunset.com/news/LionFish.jpg. Accessed 8 Aug. 2016.
Figure 5: (A) Percent of fish caught compared to the spawning ability and average temperature for each month. Numbers on top of column represent sample size. (B) Seasonality graph in Little Cayman for 2011-2012 (Gardner 2015).
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GSI = 3E-5(TL2.47 ) R² = 0.5812 GSI=3E-5(TL3.24) =Immature =Developing =Mature ovaries = Little Cayman
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References
TL
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