Morphological plasticity in Zostera muelleri across light, sediment, and nutrient gradients in Australian temperate coastal lakes

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 556:91-104 (2016) - DOI: https://doi.org/10.3354/meps11830 Morphological plasticity in Zostera muelleri across light, sediment, and nutrient gradients in Australian temperate coastal lakes Angus J. P. Ferguson1,*, Renee K. Gruber1,2, Michael Orr1, Peter Scanes1 1New South Wales Office of Environment and Heritage, Sydney, NSW 2000, Australia 2Present address: University of Western Australia, Perth, WA 6009, Australia *‑Corresponding author: angus.ferguson@environment.nsw.gov.au ABSTRACT: Biomass and morphometrics of Zostera muelleri were monitored across depth, sediment type, and nutrient gradients in 2 coastal lakes (Tuggerah Lakes and Lake Macquarie) on the east coast of Australia. Tuggerah Lakes had significantly higher nutrient, chlorophyll a, and suspended sediment concentrations in the water column and significantly higher fine sediment fraction and sediment organic matter content. Seagrass above-ground biomass (AGB) was significantly greater in the mesotrophic Tuggerah Lakes, while below-ground biomass (BGB) was significantly greater in the oligotrophic Lake Macquarie, most likely reflecting the different nutrient status of the lakes. Light gradients were the primary control over total biomass, BGB, and shoot density across the study area. Although no general trends between light and AGB were found in this study, lake- and site-specific relationships between light, AGB:BGB ratios, and leaf area index were seen to vary along gradients in nutrient status and sediment quality. These trends are thought to be driven by morphological acclimation that allows seagrass to maintain favourable plant carbon and net community metabolism balances while minimising sulphide exposure. Seagrass depth limits were best predicted by a multilinear model including Secchi depth, fine sediment fraction, and organic matter content, suggesting that negative feedbacks associated with sulphide exposure in the rhizosphere increased the minimum light requirements of this species. Our results support an emerging view that sediment quality and nutrient status are important controls over minimum light requirements in seagrasses. Morphological plasticity can moderate but not completely compensate for the negative impacts of sediment properties on minimum light requirements. KEY WORDS: Seagrass · Morphological plasticity · Depth gradient · Sediment quality · Nutrients Full text in pdf format PreviousNextCite this article as: Ferguson AJP, Gruber RK, Orr M, Scanes P (2016) Morphological plasticity in Zostera muelleri across light, sediment, and nutrient gradients in Australian temperate coastal lakes. Mar Ecol Prog Ser 556:91-104. https://doi.org/10.3354/meps11830 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 556. Online publication date: September 08, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.