Cross‐ecosystem effects of coastal urbanisation on vertebrate assemblages and ecological function

The effects of urbanisation are increasingly pervasive across landscapes, and this has implications for animals and the ecological functions they support. Differences in ecological attributes and assemblages between ecosystems means we cannot assume that different ecosystems within the same landscapes are affected by urbanisation in the same trajectory or over the same spatial scales. We test whether and how ecosystem type can modify ecological responses to urbanisation, contrasting beaches, estuaries, rocky headlands and coastal lagoons impacted by a range of urbanisation intensities on the Sunshine Coast in eastern Australia. We sampled coastal vertebrates and measured carrion scavenging, a key ecological function in all ecosystems, using baited camera traps at 85 sites distributed among five beaches (25 sites at five sites per beach), three estuaries (15 sites at five sites per estuary), four coastal lagoons (20 sites at five sites per lagoon) and five headlands (25 sites at five sites per headland). Coastal vertebrate assemblages were best predicted by the additive effects of ecosystem type and the extent of urbanisation within 5 km of each site, and this was typically characterised by increases in synanthropic species abundance at sites with high to intermediate extents of urbanisation nearby. However, two key indicator species had opposing relationships with the extent of urbanisation, and four varied only between ecosystems and not with urbanisation. Urbanisation substantially depressed rates of carrion scavenging, with some variation in species-specific consumption rates among ecosystems. While native crows, raptors and water rats accounted for 2/3 of carrion consumed, invasive black rats and free-ranging domestic dogs were significant consumers of carrion. Our results not only stress the pervasive effects of urbanisation on species distributions and abundance across multiple ecosystems in landscapes, but highlight that pivotal ecological functions can be compromised across multiple ecosystems embedded within the same landscape.