Effects of declining food availability in the deep sea
Over 99% of the seafloor relies on the slow sinking phytodetritus flux from the surface ocean. Eventually very little food arrives the seafloor and deeper we go the fewer the food availability. We are interested in the effects of declining food availability on the abundance (left), distribution (central) and diversity (right) of deep-sea benthos on the continental margins.
Understand present to reconstruct past and project future
Predicted current Seafloor biomass (Wei et al., 2010, PLOS One)
We are also interested in biological and environmental relationships in the deep sea. By understanding the present relationships, we can reconstruct the past and the project the future conditions. For example, the global seafloor biomass were predicted from the sinking food flux from the surface ocean (left); these relationships can be used to reconstructed the baseline conditions before the Gulf of Mexico deep-sea oil spill (top right), or to project future condition of the deep-sea ecosystem into 2100 (bottom right).
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Past baseline of DWH Oil Spill Site (Wei, et al. 2012, DSR II)
Future global Seafloor biomass (Jones et al. 2014 Glol. Change. Biol.)
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Biodiversity and ecosystem functioning in submarine canyon around Taiwan
With rising demands and capability to exploit deep-sea resources, the deep ocean has become the new frontier for economic development; however, the exploitation of deep sea remains highly controversial because the associated risks and environmental impacts are not well understood and the baseline data is usually lacking. To bridge the gap, it is important to understand the cumulative impacts and recovery processes of benthic communities undergo large-scale natural disturbance or submarine geohazards.
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Gaoping Submarine Canyon (GPSC) (高屏峽谷) off the SW Taiwan has been an instructional example of the source-to-sink sediment pathway from the Central Mountain Range to the deep South China Sea and thus an ideal natural laboratory to study the impacts of land-sea interactions on deep-sea benthos. Our lab currently focuses on the spatial and temporal variability of benthic communities in the GPSC, particularly, to understand the relationships between abundance, composition, diversity and functions of the seafloor communities.
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We used deep-sea multiple corer to characterized the community structure of the deep-sea benthos. We also measured the sediment grain size, carbon and nitrogen contents (proxies of food supply) from the sediments. Hydrographic parameters were measure by CTD rosette. Bottom current and duration of sediment erosion were derived from internal tide model (proxies of disturbance). For ecosystem functioning, we measured sediment community oxygen consumption (SCOC) by shipboard sediment incubation, porewater profiling and autonomous benthic lander (in developing) to quantify the transfer of carbon and nutrients between sediment water interface. Ultimately, we aim to link the community structure and ecosystem function in the deep sea.
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Hypothesis Driven StudiesWe are interested in using GPSC as natural laboratory to test ecological hypothesis and to understand the environmental controls on biological communities. For example, the Metabolic Ecology of Theory (MTE) predicts that standing stocks of animals will scale with the available resources. Since the food supply decrease with depth (because away from the surface primary production), the abundance of benthos should decline with depths. The canyon should have higher abundance, due to funneling and accumulation of organic matters; however, in a disturbed canyon, abundance may be depressed at the canyon head. The intermediate disturbance hypothesis (IDH) predicts that diversity will peak at intermediate level of disturbance. Canyon may has high diversity due to high habitat heterogeneity, but in a disturbed canyon, diversity may be depressed by turbidity, mud slides or tidal currents
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