Rachel Jeffreys - Shifts in deep-sea food webs linked to climate and food supply.
12:00pm - 1:00pm /
Friday 5th May 2017
/ Venue: Jane Herdman Lecture Theatre Jane Herdman Building
Type: Seminar /
Category: Department
- 0151 795 0619
- Jamie Hughes
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Shifts in deep-sea benthic communities detected in time-series data (> 20 years) in the NE Atlantic (Porcupine Abyssal Plain) have been linked to climate-driven variation in particulate organic matter (POM) fluxes. The effect of climate-driven variation in POM flux on food web dynamics over decades in the deep sea is unclear. I will present data on the trophic ecology of 4 deposit-feeding holothurians, Amperima rosea, Oneirophanta mutabilis, Pseudostichopus aemulatus, Psychropotes longicauda and the mud-ingesting asteroid Hyphalaster inermis, as determined by stable nitrogen isotopes (δ15N) over the time period of 1989-2005. Bulk δ15N isotopic compositions ranged from 7.8‰ in A. rosea to 16.3‰ in H. inermis and revealed clear differences between the species, reflecting differences in feeding strategies. A. rosea appears to feed on the freshest POM, while H. inermis feeds on the most refractory organic matter. Significant inter-annual differences were noted in bulk δ15N for: A. rosea, P. aemulatus and H. inermis. Nitrogen isotopic compositions of amino acids demonstrate that these inter-annual differences are related to shifts in trophic position and not variation in the δ15N of POM at the base of the food web. These results show that climate-driven variation in the POM flux does influence the dynamics of deep-sea food webs, through competitive interaction for resources.