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7 results on '"McLeay, Lachlan J."'

4. BUT FIRST, ARE YOU EXPERIENCED? THE CONSEQUENCES OF TIMING, AGE, AND ADULT CONDITION ON REPRODUCTIVE PERFORMANCE IN GREATER CRESTED TERNS THALASSEUS BERGII.

Author

McLEAY, LACHLAN J., PAGE, BRAD, and GOLDSWORTHY, SIMON D.

Subjects
*GREATER crested tern, *BIRD breeding, *SEASONAL physiological variations, *BIRD reproduction, *BIRD variation, *BIRDS, *AGE
Abstract

Among bird species with defined breeding seasons, rates of reproductive success are higher among individuals that breed earlier in the season and decrease as the season progresses. Seasonal decreases in breeding success have been explained by decreases in prey availability or by variations in parental "quality," mediated by age-related experience or phenotype. We examined seasonal patterns of primary production, as an indicator of prey availability, in relation to the breeding phenology of three Greater Crested Tent Thalasseus bergii colonies in gulf waters of South Australia. We then determined the influence of reproductive timing on the reproductive performance (chick growth and survival) of Greater Crested Terns and the role of parental "quality" in reproductive success by measuring reproductive timing in relation to parental age and body condition. In contrast to expectations, increased primary production was observed in winter months, long after the chick fledging period. High production in winter may benefit newly fledged juvenile terns that have relatively less skill and experience than adults. Chick hatching was synchronised among colonies located 250 km apart, and the timing of breeding had a significant effect on reproductive performance. Chicks reared by older adults hatched earlier in the breeding season than younger adults, and exhibited better growth and body condition (hatch mass, linear growth rate, and asymptotic mass) and higher rates of survival. There was less support for the effects of body condition, measured by a body condition index (BCD. on reproductive timing, and no significant relationship between adult age and body condition. However, individuals less than seven years old had significantly poorer body condition than those that were older. The seasonal patterns in age-related breeding success we observed may be explained by parents' age-related improvements in breeding and foraging proficiency, shaped through their need to provision their chicks with a single prey item that is small enough for the chick to swallow. [ABSTRACT FROM AUTHOR]

Published
2017

6. Pelagic ecology of a northern boundary current system: effects of upwelling on the production and distribution of sardine (Sardinops sagax), anchovy (Engraulis australis) and southern bluefin tuna (Thunnus maccoyii) in the Great Australian Bight

Author

WARD, TIM M., primary, MCLEAY, LACHLAN J., additional, DIMMLICH, WETJENS F., additional, ROGERS, PAUL J., additional, MCCLATCHIE, SAM, additional, MATTHEWS, ROGER, additional, KÄMPF, JOCHEN, additional, and VAN RUTH, PAUL D., additional

Published
2006
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7. Trophodynamics of the eastern Great Australian Bight ecosystem: ecological change associated with the growth of Australia's largest fishery

Author

Charlie Huveneers, Lachlan J. McLeay, Michelle Braley, Brad Page, Tim M. Ward, Andrew D. Lowther, Keryn Daly, C Bulman, Alastair M. M. Baylis, Annelise Wiebkin, Paul J. Rogers, Luke D. Einoder, Robin Caines, Simon D. Goldsworthy, Kristian J. Peters, Goldsworthy, Simon D, Page, Brad, Rogers, Paul J, Bulman, Cathy, Wiebkin, Annelise, McLeay, Lachlan J, Einoder, Luke, Baylis, Alastair MM, Braley, Michelle, Daly, Keryn, Huveneers, Charlie, Peters, Kristian, Lowther, Andrew D, and Ward, Tim M

Subjects
Ecosystem health, Biomass (ecology), Ecology, Sardinops sagax, Ecological Modeling, fishing impacts, Fishing, food web model, Eastern Great Australian Bight, sardine, Fishery, Geography, Ecopath with Ecosim, Forage fish, EcoSim, Ecosystem, Trophic level, Apex predator
Abstract

We used the Ecopath with Ecosim software to develop a trophic mass-balance model of the eastern Great Australian Bight ecosystem, off southern Australia. Results provide an ecosystem perspective of Australia's largest fishery, the South Australian sardine fishery, by placing its establishment and growth in the context of other dynamic changes in the ecosystem, including: the development of other fisheries; changing abundances of apex predator populations and oceanographic change. We investigated the potential impacts of the sardine fishery on high tropic level predators, particularly land-breeding seals and seabirds which may be suitable ecological performance indicators of ecosystem health. Results indicate that despite the rapid growth of the sardine fishery since 1991, there has likely been a negligible fishery impact on other modelled groups, suggesting that current levels of fishing effort are not impacting negatively on the broader ecosystem structure and function in the eastern Great Australian Bight. Results highlight the importance of small pelagic fish to higher trophic levels, the trophic changes that have resulted from loss and recovery of apex predator populations, and the potential pivotal role of cephalopod biomass in regulating 'bottom-up' trophic processes. The ability to resolve and attribute potential impacts from multiple fisheries, other human impacts and ecological change in this poorly understood region is highlighted by the study, and will be critical to ensure future ecologically sustainable development within the region. Refereed/Peer-reviewed

Published
2013

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