Sandpipers go with the flow: Correlations between estuarine conditions and shorebird abundance at an important stopover on the Pacific Flyway

Abstract

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Biofilm and invertebrate consumption by western sandpipers (Calidris mauri) and dunlin (Calidris alpina)during spring migratory stopover: insights from tissue and breath CO2 isotopic (δ13C,δ15N) analyses

“…The realization of intertidal biofilm being not only a source of energy (quantity) but also long-chain highly unsaturated fatty acids, such as Omega-3 (quality), essential to shorebirds on long-distance migration ( Guglielmo, 2018 ; Young et al , 2021 ) has opened new insight on the ecological mechanisms underpinning stopover site functioning and, when they fail, a plausible hypothesis to explain population declines in migratory shorebird species worldwide ( Mathot et al , 2018 ; Studds et al, 2017 ; Wilson et al , 2011 ). In doing so, recent studies into western sandpiper use of intertidal biofilm in the Fraser River estuary offer hope on how deeper appreciation of physiological requirements can boost understanding of shorebird migration generally and better inform conservation (Schnurr et al, 2018, Schnurr et al, 2020 ; Canham et al , 2021 ). In summary, given rapidly increasing anthropogenic threats, isotopic tissue and breath methodology offers a critical new tool to understand how spatio-temporal patterns in the biofilm ‘landscape’ align with the physiological demands of migrating shorebirds and a means to more effective conservation and restoration for stopover sites globally ( Kuwae et al , 2021 ).…”

Assessing diatom-mediated fatty acids in intertidal biofilm: a new conservation concern

“…Worldwide, a growing appreciation for the benefits of intertidal mudflat habitats has given alarm to the potential negative effects of climate change and coastal development to both mudflat quality and quantity. In particular, as the quality of intertidal biofilm can be gauged by the production of diatom-mediated fatty acids (Schnurr et al 2020;Canham et al 2021), the predicted reduced production of polyunsaturated fatty acids in algae due to global warming (Hixson and Arts 2016;Colombo et al 2020) compounded by losses in mudflat quantity (Murray et al 2019) are likely to result in irreversible and fundamentally adverse changes to these coastal systems. Establishing robust and routine analytical techniques to temporally monitor the quality and condition of mudflats, in tandem with research programs to achieve a deeper understanding of mudflat ecology, are core to effective conservation.…”

“…Concomitantly, threats to diatomaceous biofilm on intertidal mudflats from climate change and anthropogenic stressors are raising new conservation concerns related to shorebirds (Beninger 2018). Worldwide declines in the abundance of most migratory shorebird species (Clemens et al 2016;Studds et al 2017;Rosenberg et al 2019;Canham et al 2021) have occurred in tandem with average losses to their intertidal flat habitats at 16% of their total area between 1984 and 2016 (Murray et al 2019). Mudflat habitats have long been known to provide wide-ranging ecosystem services that support fish and wildlife (Beninger 2018) but have assumed even more importance in recent years with the discovery that many shorebird species consume intertidal biofilm rich in fatty acids produced by diatoms to support their long-distance migration (Schnurr et al 2019(Schnurr et al , 2020.…”

Seven ecological and technical attributes for biofilm‐based recovery of shorebird populations in intertidal flat ecosystems

“…However, if seawater flowing onto an intertidal flat is already nutrient-rich, then additional sources of nutrients may not be necessary. The mixing of freshwater with seawater is a key attribute of functional intertidal flats (Canham et al, 2021). (Schnurr et al, 2020).…”

“…If we focus on the recovery of shorebird populations, the value of interventions into artificial intertidal flat ecosystems depends on their capacity to generate the required quantity and quality of food sources at the 'right' time, especially at stopover/staging sites used for re-fuelling during long-distance migration (Canham et al, 2021;Mathot et al, 2018). Consequently, intervention must be founded on sound understanding of food web structure, energy flow and the cycling of nutrients.…”