Decadal decline in demersal fish biomass coincident with a prolonged drought and the introduction of an exotic starfish

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 544:37-52 (2016) - DOI: https://doi.org/10.3354/meps11577 Decadal decline in demersal fish biomass coincident with a prolonged drought and the introduction of an exotic starfish G. D. Parry1,*, A. J. Hirst2 1Monash University, Clayton, Victoria, Australia, and MES, PO Box 265, Queenscliff, Victoria, Australia 3225 2Centre for Integrative Ecology, Deakin University, Waurn Ponds, Victoria, Australia 3216 *Corresponding author: [e-mail] ABSTRACT: Between 1990 and 2011, Port Phillip Bay in southern Australia experienced 2 major ecological disturbances: a prolonged drought from 1997 to 2010, and the introduction of the invasive starfish, Asterias amurensis. The drought reduced land-based nitrogen inputs by 64%, and the biomass of A. amurensis in the deep centre of the bay peaked at 56% of the resident fish biomass in 2000. The impacts of these disturbances on fish were assessed using a demersal trawl time-series spanning 2 decades (1990 to 2011). The timing and spatial extent of changes to fish biomass were analysed using ANCOVA and change point analysis. During the drought, fish biomass declined by 69% in the deep centre of the bay, by 50% at intermediate depths, and showed no significant change around the shallow fringes. This spatial pattern is consistent with hydrodynamic modelling, which suggests that during the drought a greater proportion of the (lower) nitrogen input was retained near the coastal fringe. Most of the decline in fish biomass was attributed to the cumulative effects of reduced productivity during the 12 yr drought. However, declines in 3 species in the deep region were attributed to competition with A. amurensis. Each of these species exhibited high dietary overlap with A. amurensis and displayed sharp declines in biomass coinciding with the peak abundance of A. amurensis in 2000. KEY WORDS: Nutrient · Drought · Asterias · Exotic species · Trawl time-series · Port Phillip Bay Full text in pdf format Supplementary material PreviousNextCite this article as: Parry GD, Hirst AJ (2016) Decadal decline in demersal fish biomass coincident with a prolonged drought and the introduction of an exotic starfish. Mar Ecol Prog Ser 544:37-52. https://doi.org/10.3354/meps11577 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 544. Online publication date: February 18, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.