Territory Stories

Identifying sources of surface water turbidity in the Elizabeth River Estuary

Details:

Title

Identifying sources of surface water turbidity in the Elizabeth River Estuary

Creator

Streten, Claire; Logan, Murray; Spagnol, Simon; Brinkman, Richard

Collection

E-Publications; E-Books; PublicationNT; 32/2020

Date

2020-06-01

Location

Darwin Harbour

Description

The Elizabeth River is one of the major tributaries of Darwin Harbour and freshwater outflows from this river influences the water quality in Inner Darwin Harbour. During flood events the turbid plumes from the Elizabeth River have the potential to cause increased turbidity levels in Inner Darwin Harbour. Reduced light availability, because of elevated turbidity, may reduce the growth and reproduction of photosynthetic organisms such as seagrass and coral symbionts. In addition, high turbidity levels have the potential to cause stress to marine life due to smothering. Thus, elevated turbidity levels can have a negative impact on the health of Darwin Harbour. Without knowledge of what variables drive elevated turbidity levels in the Elizabeth River, it is not possible to assert the effect freshwater flows have on turbidity in the Inner Harbour. This study used two approaches to develop a clearer picture of the drivers of variability of turbidity within the Elizabeth River estuary: 1. Gradient boosted regression tree models were used to unravel the relationship between surface turbidity and potential sources 2. Water column bacteria communities were characterised to assess if they are potential indicator of sediment provenance.

Notes

Made available by via Publications (Legal Deposit) Act 2004 (NT).

Table of contents

Summary 1 Background 2 Methods 2.1 Data for statistical model analysis 2.2 Statistical model runs 2.2.1 Gradient boosted model 2.2.2 Extreme gradient boosted 2.3 Sampling sites for bacteria community analysis 2.4 Water and sediment collection 2.5 Water column nutrient analysis 2.6 DNA extraction, sequencing and analysis 3 Results and Discussion 3.1 Gradient boosted tree model 3.2 Bacteria as indicators of source of turbidity 4 Conclusions 5 References Appendix A: Extreme gradient boosting Appendix B: Genera significantly different in water between sampling points Appendix C: Genera significantly different in water with < 10 and > 10 turbidity

Language

English

Subject

Darwin Harbour turbidity

Publisher name

Northern Territory Government

Place of publication

Darwin

Series

32/2020

File type

application/pdf

ISBN

9781743502556

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Parent handle

https://hdl.handle.net/10070/802143

Citation address

https://hdl.handle.net/10070/802144


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