ECR Feature: Yuting Vicky Lin on reef fish and climate change

Yuting Vicky Lin is a PhD student at the Institute of Oceanopgraphy at National Taiwan University. Her interests lie in the biodiversity and conservation of benthic reef communities. Vicky shares her recent work on forecasting the distribution of coral reef fish under a changing climate

(left) Vicky, diving in Tawai. Photo credit: Guan Yen Chen and Yuting Vicky Lin. (right) Tropical habitats with complex morphologies of corals and high richness in reef fishes. The picture was taken in the shallow waters (10 meters in depth) of Green Island, Taiwan. Photo credit: Yuting Vicky Lin.

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Institute. Institute of Oceanography, National Taiwan University

Academic life stage. PhD.

Major research themes. My research focuses on community ecology, benthic ecology, coral reef ecology, marine biodiversity and conservation. I am particularly interested in the impacts of climate change and pollution on marine ecosystems.

Current study system. I am studying marine coastal benthic communities with a specific focus on their structures, the environmental drivers responsible for their structuring, and the responses of their associated reef fishes to climate change. These benthic communities are composed of diverse sessile megabenthos, such as corals, algae, and sponges. These communities function as houses for reef fishes, and are used as shelters, nurseries, feeding, or reproduction grounds by fishes across life history stages. However, ongoing climate change and marine pollution are jeopardizing these benthic communities, which may, in turn, have a cascading effect on their associated fish species. My job is to understand how benthic communities and their associated reef fishes are affected by climate change and human activities and anticipating future coastal ecosystems. This information could be critical for the conservation management of coastal ecosystems.

Recent paper in JBI. Lin YV, Hsiao WV, Chen W-J, Denis V (2022) Habitat change and its consequences on reef fish specialization in biogeographic transition zones, Journal of Biogeography, 49, 1549-1561. DOI: 10.1111/jbi.14450

Different reefal organisms rely on marine sessile benthos. (top left) A sea anemone provides shelter and residence to a clownfish. (top right) A vermetid snail inhabits under a scleractinian coral. (bottom left) A crab uses a Acropora coral as the shelter and residence. (bottom right) Two egg cowries are eating Alcyonacea corals. Photo credit: Yuting Vicky Lin.

Motivation behind this paper. To survive under the threats of global warming, reef fishes have been documented to move their distribution poleward as suitable environments expand. Temperature plays an important role in this distributional shift and has been a major focus in previous works. In this aspect, the dependence of fish on benthic habitats has often been ignored, although it could be a critical factor to consider for species having a strong affinity for benthic resources. Specifically, understanding how temperature and benthic habitat constrain the present distribution of reef fishes can help better predict future distributions of fishes in the warming ocean. This is especially paramount in biogeographic transitions where distributional shifts of species have often been observed. The position of Taiwan as a tropical-subtropical transition zone implies that it has likely been an important pivot point in the distributional shift of benthic communities and their associated fishes under climatic change. We, therefore, used this feature of Taiwan to infer the importance of habitat tracking, warming tracking, or their interplay on the distribution of reef fish.

Key methods. The novelty of our paper resides in combining several analytical approaches to test the effects of temperature and benthic habitat in constraining the current distribution of reef fishes. To do this, we first collected fish and benthic data from underwater transect surveys as well as sea temperature from satellite-based meteorological data at 18 sites along the tropical-subtropical gradient in Taiwan. We then applied several analyses such as k-means, bipartite networks, species indicator analysis, and joint-species distribution models in order to 1) distinguish tropical and subtropical benthic habitats, 2) identify fish specialist and generalist species to either tropical or subtropical habitats, and finally 3) test whether the current distributions of these specialists were controlled by temperature, benthic habitat, or both combined. Among these specialists, we further selected fishes whose distributions were strongly constrained by both factors as warming indicators and proposed to use these indicators to track changes in the thermal and benthic environment.

Major results. We demonstrated three responses by reef fish habitat specialists: 1) those constrained by temperature alone; 2) those constrained by benthic habitat alone; or 3) or those constrained by both temperature and benthic habitat. Among the specialists constrained by both factors, we proposed three species as the indicators to track both the temperature and benthic habitat changes in the future, as their distributions were strongly constrained by these two factors compared with other specialists. Consequently, we proposed two scenarios for fish specialists under ocean warming: 1) the distribution of some species may shift according to the poleward movement of a suitable thermal environment; 2) the distribution of some others may change following the poleward shift of both suitable thermal and benthic environments. These results showed that not all fishes have the same responses to environmental change. We also highlight the need to consider the benthic habitat to explicitly estimate the responses of reef fishes to ocean warming.

Three fishes were identified as indicators of tropicalization in Taiwan (left panel) following both fish and benthic surveys in the country (right panel). Photo credit: Tsai-Hsuan Tony Hsu and Yuting Vicky Lin.

Challenges overcome. We encountered two major challenges in this research. The first one was acquiring enough sampling locations to represent the tropical-subtropical gradient while working on a short research budget. It was especially challenging at some sites located on the East coast of Taiwan, where many areas remain unexplored. Some of the sites are managed by indigenous people and we had to explain our research to local residents in order to receive their approval to perform our surveys. During our discussion, we understood more about how indigenous tribes manage coastal resources and the importance of preserving traditional ecological knowledge. The second challenge was that our initial version of this manuscript did not actually disentangle the effects of benthic habitat from sea surface temperature on reef fish distribution. Fortunately, the reviewers were very helpful and guided us with very constructive suggestions greatly improving our analytical framework. The review was tough, but inspiring. We learned a lot from it and are extremely glad about the outcomes. 

Next steps? The next step should be to acquire the long-term fish and benthic data to confirm our hypotheses. Especially, we would like to verify if the indicators we proposed could respond as expected and reflect more severe changes affecting the ecosystems. In addition, it would also be interesting if we could apply a similar methodology to the other reef taxa that likewise rely on the benthos, such as molluscs. The answers to those questions will encourage us to think deeply about how to adapt the coastal conservation according to the local situations, eventually resulting in a customized management rather than a one-size-fits-all one.

If you could study any organism on Earth, what would it be? I am interested in all reef marine organisms. In addition to the reef fishes that I studied in this paper, I would like to perform similar research using nudibranchs (sea slugs) since they are often highly specialized in their food sources, primarily benthic organisms such as corals, sponges, and algae. Accordingly, I expect that they could be highly sensitive to the changes in benthic habitats and could represent even better sentinels of environmental changes than reef fishes. Their striking beauty and colors often attract my attention as an amateur underwater photographer. However, there is very little understanding of their taxonomy, ecology, and behaviors which I would like to improve if I have the opportunity.   

Anything else to add? If you are interested in my research or would like to have some collaborations, feel free to contact me by email (vicky.linyuting@gmail.com)

Published by jbiogeography

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