Impact of small-scale environmental perturbations on local marine food resources: a case study of a predator, the little penguin

Abstract

Although the impact of environmental changes on the demographic parameters of top predators is well established, the mechanisms by which populations are affected remain poorly understood. Here, we show that a reduction in the thermal stratification of coastal water masses between 2005 and 2006 was associated with reduced foraging and breeding success of little penguins Eudyptula minor, major bio-indicators of the Bass Strait ecosystem in southern Australia. The foraging patterns of the penguins suggest that their prey disperse widely in poorly stratified waters, leading to reduced foraging efficiency and poor breeding success. Mixed water regimes resulting from storms are currently unusual during the breeding period of these birds, but are expected to become more frequent due to climate change.

Two Recent Massive Breeding Failures in an Adélie Penguin Colony Call for the Creation of a Marine Protected Area in D'Urville Sea/Mertz

“…In the remainder of the analyses we will focus on comparing the conditions between the zero success years (2013-14 and 2016-17 seasons) and the typical high breeding season of 2015-16. We chose this season because its breeding success is exceptionally high in comparison with other recent years (post 2010 and Mertz glacier calving, see Discussion) and as such causes and consequences are expected to be exacerbated (see Ropert-Coudert et al, 2009 for a similar test case). In addition, 2015-16 is the only year of high breeding success for which we have tracking data.…”

Key Questions in Marine Megafauna Movement Ecology

“…The physical structure of the water column also acts to accumulate both megafauna and prey through oceanographic features ranging from thermoclines (10-100 m), eddies and upwelling zones (10-100 km), to boundary currents (1000 km) [6]. Disentangling the direct effects of the physical environment on the movement and behaviour of megafauna from indirect effects on their prey remains a significant challenge [43].…”

Seasonal ocean temperature and the survival of first-year little penguins Eudyptula minor in south-eastern Australia

“…More immediate effects of temperature on seabirds may involve relationships between temperature and the distribution and availability of prey. For example, Ropert-Coudert et al (2009) have proposed that the presence of thermoclines may assist foraging success in little penguins Eudyptula minor.…”