This article is written by Iris Uijttewaal, with contribution of Dr. Mario Lebrato.
Extreme or catastrophic events in the natural environment are rare opportunities to study and understand ecosystems pushed to the limit. These occasions facilitate the understanding of how life adapts to a continuous changing world, where fundamental events can disrupt normality. A series of catastrophic events triggered by a C5 typhoon and a M5.8 earthquake off the coast of Taiwan (West Pacific Ocean) were used in a new scientific paper, to understand benthic organisms ecosystem adaptations using stable isotopes to analyse dietary shifts, coupled to environmental change.
The research team dived of the coast of Turtle Island to collect data (Photo by Carsten Peter)
By monitoring hydrothermal vent systems, important biodiversity hotspots hosting a vast array of unique species, information on life’s evolutionary adaptations to extreme environments can be retrieved. The shallow hydrothermal vents of Turtle Island, off the coast of Taiwan, were used as a natural laboratory to examine the response of benthic organisms and ecosystems to the before-mentioned earthquake and typhoon that led to a two-year near shutdown of the vents. The local biogeochemical cycle and dietary availability of chemosynthetic vs photosynthetic food resources were drastically altered as a result. The paper analysed stable isotopes including those of sulphur, carbon, and nitrogen (δ34S, δ13C, and δ15N) from different benthic macrofauna, revealing different responses to disruption in habitat among consumers. The findings highlight how benthic specialists prove to be vulnerable to the increasing environmental pressures caused by human activities globally.
Vent crabs (Xenograpsus testudinatus) in the hydrothermal vent system at Kueishantao, off the coast of Taiwan. The paper highlights that vent crabs (X. testudinatus) continued to partially rely on chemosynthetic sulphur bacteria despite photosynthetic sources being the most dominant food source after the disruption. (Photo by Dr. Mario Lebrato)
Multiple stable isotopes are non-radioactive forms of atoms, which can be used as environmental tracers in seawater and/or in the animal’s body. In the Taiwan catastrophic events, the use of sulphur, carbon, and nitrogen isotopes (δ34S, δ13C, and δ15N), from different benthic animals, revealed that endemic and non-endemic consumers exhibited different responses to sudden disruption in habitat and biogeochemical cycling. For example, the paper highlights that vent crabs (X. testudinatus) continued to partially rely on chemosynthetic sulphur bacteria despite photosynthetic sources being the most dominant food source after the disruption. Isotopes are commonly used to assess nutritional interactions in trophic webs and can then be used as tracers for habitat/food/conditions alteration.
Vent activity off the coast of Kuishantao before the C5 typhoon and M5.8 earthquake. (Photo by Li-Chun Tseng and Jiang- Shiou Huang via Max Planck Institute of Geoanthropology)
Isotopes can also be used to track climate change impact on ecosystems, for example to through assessing dietary plasticity following sudden disturbance events like cyclones or using time-series work on monthly environmental change. BCSS works with isotopes using organic trophic web samples, and also other bio-tracers of anthropogenic activity (e.g. heavy metals, PCBs, dioxins, or plastic-derived compound tracers), to understand time-series changes associated to biogeochemical cycles, and physical processes. The maintenance of BCSS time-series work under the Ocean Observatory can reveal weekly/monthly resolution onto isotopes and other bio-markers trends over time to understand climate change-derived ecosystem structural changes, normal variability, sudden shifts, human-consumption risks (on fish). Occasionally, the time-series work can also help to understand the impact of cyclones such as the Freddy Cyclone event that recently made landfall in Mozambique.
BCSS’s Chief Scientist Dr. Mario Lebrato contributed to the paper “Foraging under extreme events: Contrasting adaptations by benthic macrofauna to drastic biogeochemical disturbance” by developing and executing fieldwork, conducting scientific diving, recovering samples and providing all seawater physicochemical work to couple with the biology work done in the laboratory. Lebrato worked together with an international team of scientists: PI Yiming V. Wang, and co-authors Thomas Larsen, Li-Chun Tseng, Pei-Wen Lee, Nicolás Sánchez, Juan-Carlos Molinero, Jiang-Shiou Hwang, Tin-Yam Chan and Dieter Garbe-Schönberg.
For questions about this article, please contact:Iris Uijttewaal, Bazaruto Center for Scientific StudiesIris.Uijttewaal@bcssmz.org
Bazaruto Center for Scientific StudiesHost of the first permanent Ocean Observatory focused on multi-ecosystem time series research in Africa, the Bazaruto Center for Scientific Studies (BCSS) was established in 2017 as in independent, non-profit organisation with a mission to protect and support the fragile ecosystems of the Bazaruto Archipelago, Mozambique. The research station is located on Benguerra Island, off the coast of Mozambique.
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