• SPF trophic relationships to food availability studied with fatty acids and stable isotopes. • Niche width and energy content of SPF increased with chl-a concentration, a food proxy. • Niche overlap independent of chl-a or zooplankton concentrations; higher in the west. • Round herring > anchovy > sardine trophic levels confirmed; round herring 25 % fattier. Small pelagic fishes (SPF) in eastern boundary upwelling systems share space and must adapt to strong seasonal and inter-annual variations in their environment. This raises questions about how these species share food resources in a changing environment and whether they compete with each other when their food resources are reduced. We approach these questions on three SPF species (sardine Sardinops sagax , anchovy Engraulis encrasicolus and round herring Etrumeus whiteheadi ) living on the west and south coasts of South Africa. We combined fish muscle fatty acid profiles as a proxy for prey taxa diversity, stable isotope compositions as a proxy for habitat and trophic position, and satellite-derived chlorophyll-a and zooplankton concentrations as proxies for food availability. We found that the total fatty acid content (energy reserve) of the three species increased with chlorophyll-a concentration, suggesting that chlorophyll-a is a good proxy for food quantity. For the three SPF species, the niche width increased with the amount of chlorophyll-a. However, the niche overlap (i.e. the potential for competition) remained relatively unchanged as chlorophyll-a concentrations increased, though it varied considerably depending on local conditions (from 0 to 100 %), higher on the west coast (influenced by the Benguela upwelling) than in the south coast.. The relative trophic level of the species (round herring > anchovy > sardine) was confirmed in both regions and the round herring remained on average 25 % fattier than the other two species. These results suggest that on a relatively short time scale (month) SPF species are more selective when food levels decrease but that competition for resources may or may not operate depending on local conditions. However, integrated over a larger time scale, the three species do feed on different resources (resulting in different trophic levels) and cannot be considered an ecological substitute. The recent changes in their respective biomasses could impact the amount of fat (energy) available to higher trophic levels.

• First synthesis of megafauna, macrofauna, and meiofauna responses to turbidity flows. • Used 2016 Kaikōura Earthquake canyon-flushing as natural disturbance experiment. • Novel method was used to predict full recovery time for each size class. • Kaikōura Canyon benthic community showed overall resilience to major disturbance. • Life-history traits influenced differential recovery patterns among size classes. Sediment density flows are complex events that contain multiple flow types which can transport massive amounts of sediment across large distances. Turbidity flows are believed to have profound and lasting impacts on benthic communities in the deep sea. A canyon-flushing event in Kaikōura Canyon, New Zealand, triggered by the 2016 M w 7.8 Kaikōura Earthquake, included significant submarine mass wasting, debris, and turbidity flows, and provided an opportunity to investigate the effects of this disturbance. Previous studies have analysed the mega-, macro-, and meiofauna community structure, before and after the event using a time series of imagery and sediment cores. Additionally, community recovery was investigated in relation to changes in the physical characteristics of the habitat, using environmental variables from images and bathymetric variables and sediment cores. However, no attempt has been made to examine the overall community response to turbidity flow disturbance or to consider interactions between the different size classes. To address this gap, the data and results for each size class in Kaikōura Canyon were synthesised here with an emphasis on assessing the overall deep-sea benthic community response, and predicting time to recovery for the full community in Kaikōura Canyon. Overall, the benthic community in Kaikoura Canyon appears to be resilient to the disturbance with meiofauna showing the fastest recovery time followed by megafauna and then macrofauna. Differences in the life-history characteristics of mega-, macro- and meiofauna, as well as various interactions among the faunal size class communities, likely have influenced the recovery patterns observed.