Saltmarsh grass supports fishery food webs in subtropical Australian estuaries

Jinks, Kristin I., Rasheed, Michael A., Brown, Christopher J., Olds, Andrew D., Schlacher, Thomas A., Sheaves, Marcus, York, Paul H., and Connolly, Rod M. (2020) Saltmarsh grass supports fishery food webs in subtropical Australian estuaries. Estuarine, Coastal and Shelf Science, 238. 106719.

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Abstract

All fishery food webs are ultimately underpinned by organic matter produced by algae and plants, some of it supplied by primary producers at the fringes of fish habitats. This is no different in tropical and subtropical estuaries where secondary production by crustaceans and finfish may depend on coastal wetlands (e.g. mangroves, seagrass, saltmarshes) abutting channels. Coastal urbanisation is a major cause of wetland loss globally. Hypothetically, reduced wetland area may propagate to less fisheries production if wetland contributions to food webs are substantial – this is the prime question addressed here. We sampled key fisheries species in subtropical estuaries in reaches of moderate urbanisation (18–33% of shoreline hardened) and in reference locations dominated by wetlands, on the east coast of Australia. We used triple stable isotopes (C, N, S) to estimate (using mixing models) the trophic contributions of the key primary producers to regional fisheries species. Organic matter from wetland plants, particularly saltmarsh grass (Sporobolus virginicus), underpinned fishery food webs in most cases (with median contributions ranging from 18 to 88% for saltmarsh grass, followed by 6–70% for C3 wetland plants (e.g. mangroves, phragmites) and 3–36% by benthic algae). Moderate levels of urban transformation of estuarine margins did not change the dominance of wetland carbon for fish and crustaceans in settings without significant seagrass meadows. Given the demonstrated importance of saltmarshes, and other coastal wetlands, to regional fisheries production, conservation of these habitats is necessary in the face of multiple anthropogenic threats.

Item ID: 62680
Item Type: Article (Research - C1)
ISSN: 1096-0015
Keywords: Coastal wetlands; Salt marsh; Sporobolus virginicus; Sulfur; Urbanization; Fisheries
Copyright Information: © 2020 Elsevier Ltd. All rights reserved
Funders: Queensland Government (QG), Australian Research Council (ARC), The Global Wetland Project
Projects and Grants: QG grant - DAF1498CQB, ARC Linkage Grant LP160100492, ARC Discovery Early Career Researcher Award DE160101207, ARC Discovery Project DP180103124
Date Deposited: 05 Apr 2020 23:53
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050102 Ecosystem Function @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960603 Environmental Lifecycle Assessment @ 50%
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