疣狀鹿角珊瑚(Pocillopora verrucosa)複合種群的族群生態學

Population ecology of the Pocillopora verrucosa species complex

莫艾奇(Mulla Aziz Jabir)

指導教授 ： 野澤洋耕

國立臺灣師範大學/理學院/生命科學系/博士(2022年)

https://doi.org/10.6345/NTNU202200690

摘要

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關鍵字

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並列摘要

Population ecology is the study of populations in relation to the environment that includes the influences on population structure, health and density. For centuries it has provided a means of evaluating why and how populations change over time, why some go extinct and why others flourish. However, we still lack critical demographic information on specific foundational species, especially when it comes to corals, that promote the resilience of coral reefs worldwide. In this Ph.D. study, I explore mechanisms that support the survival of the Pocillopora verrucosa species complex, an abundant group of coral species in the Indo-Pacific. I examine abiotic factors on the larvae of P. verrucosa during dispersal (Chapter 2), use long-term monitoring and mathematical modelling to exemplify ecosystem resilience (Chapter 3) and reveal the demographic processes that drive population growth (Chapter 4).
Our results from Chapter 2 show that behaviour can have profound consequences for the dispersal potential of marine sessile organisms. I show that larvae of P. verrucosa are photo-sensitive and use this ability to dwell at the surface after spawning. Other coral species tested showed no preference towards or away from the light source, possibly using other mechanisms to regulate their vertical positioning. This reaction was consistently observed both in the laboratory at different light intensities and in the field at various depths. I hypothesise that photo-movement may have some influence on the wide geographical distribution of P. verrucosa.
In Chapter 3, I explore Pocillopora populations in recovery in Lanyu, Taiwan after a catastrophic disturbance in 2009. I monitored individual colonies over a 9-year period (2012-2020), tracking growth, survival and reproduction. I used Integral Projection Models (IPMs) to extract demographic traits that drive population recovery following a disturbance. Our results exemplified resilience as the population in later years was able to absorb recurrent disturbances and continue on the trajectory of recovery. I show it is underlying mechanisms such as the transition of smaller immature individuals to sexually mature adults that ensure the progression of the population. Our results deepen our knowledge of the value of both empirical and theoretical methods to explore recovery of corals.
In Chapter 4, I scrutinized the demographic traits associated with Pocillopora populations that regulate and facilitate population growth. I discovered, to our best knowledge, the first clear evidence of self-thinning of a coral population, a law in ecology whereby the number of individuals (per unit area) decreases as average size increases over time. I highlighted processes that drive this phenomena concluding that density-dependent recruitment is exerting pressure on the population to shrink in number of individuals. Our understanding what factors regulate population growth of foundational organisms is essential for future predictions of coral reefs.
Further research is necessary to explore the recovery potential of coral reefs. From reproduction to population dynamics to interdisciplinary science, population ecology has a place in the 21st century and can help to address new questions arising due to anthropogenic climate change. This Ph.D. study shows that mechanisms underpinning the survival of foundational organisms offer insight into how coral reefs will look in the future under more pressured environmental change.

並列關鍵字

Coral ； Ecology ； Larvae ； Recovery ； Demography

參考文獻

Abelson, A., Olinky, R. & S. Gaines. (2005). Coral recruitment to the reefs of Eilat, Red Sea: temporal and spatial variation, and possible effects of anthropogenic disturbances. Mar. Poll. Bull. 50, 576-582.

Adamska, M. et al. (2007). Wnt and TGF-β Expression in the Sponge Amphimedon queenslandica and the Origin of Metazoan Embryonic Patterning. PLoS ONE 10 e1031

Adjeroud, M., Kayal, M., & Penin, L. (2017) Importance of Recruitment Processes in the Dynamics and Resilience of Coral Reef Assemblages. In: Rossi S., Bramanti L., Gori A., Orejas C. (eds) Marine Animal Forests. Springer, Cham. https://doi.org/10.1007/978-3-319-21012-4_12

Adjeroud, M., Kayal, M., Iborra-Cantonnet, C. et al. (2018). Recovery of coral assemblages despite acute and recurrent disturbances on a South Central Pacific reef. Sci Rep 8, 9680

Adjeroud, M., Michonneau, F., Edmunds, P.J., Chancerelle, Y., Lison de Loma, T., Penin, L., Thibaut, L., Vidal-Dupiol, J., Salvat, B. & Galzin, R. (2009) Recurrent disturbances, recovery trajectories, and resilience of coral assemblages on a South-Central Pacific reef. Coral Reefs, 28, 775–780