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The Effect of Water Temperature on Aquatic Organisms: a Review of Knowledge and Methods for Assessing Biotic Responses to Temperature

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The effect of water temperature on aquatic organisms: a review of knowledge and methods for assessing biotic responses to temperature Report to the Water Research Commission by Helen Dallas The Freshwater Consulting Group Freshwater Research Unit Department of Zoology University of Cape Town WRC Report No. KV 213/09 30 28 26 24 22 C) o 20 18 16 14 Temperature ( 12 10 8 6 4 Jul '92 Jul Oct '91 Apr '92 Jun '92 Jan '93 Mar '92 Feb '92 Feb '93 Aug '91 Nov '91 Nov '91 Dec Aug '92 Sep '92 '92 Nov '92 Dec May '92 Sept '91 Month and Year i Obtainable from Water Research Commission Private Bag X03 GEZINA, 0031 [email protected] The publication of this report emanates from a project entitled: The effect of water temperature on aquatic organisms: A review of knowledge and methods for assessing biotic responses to temperature (WRC project no K8/690). DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use ISBN978-1-77005-731-9 Printed in the Republic of South Africa ii Preface This report comprises five deliverables for the one-year consultancy project to the Water Research Commission, entitled “The effect of water temperature on aquatic organisms – a review of knowledge and methods for assessing biotic responses to temperature” (K8-690). Deliverable 1 (Chapter 1) is a literature review aimed at consolidating available information pertaining to water temperature in aquatic ecosystems. The review describes the: importance of water temperature in aquatic ecosystems, including spatial and temporal variation in water temperature; measurement of water temperature in river systems, including in situ measurement and modelling; anthropogenic factors that modify water temperature; effects of water temperature on the physical and chemical characteristics of water; effects of water temperature on aquatic organisms and ecosystems; assessment of the effects of temperature changes on aquatic organisms, including thermal tolerance, sublethal effects and behavioural preference and avoidance; and water temperature guidelines for the protection of aquatic ecosystem. South African examples are given in instances where they are available, although generally local information on the effect of water temperature on aquatic organisms and ecosystems is relatively scarce. Deliverable 2 is a scientific paper based on the literature review and submitted to Water SA. This review paper will enhance dissemination of existing knowledge on water temperature and aquatic organisms. Deliverable 3 (Chapter 2) is a short report on site selection for the installation and testing of temperature loggers, and includes data collected during the consultancy on within-site spatial variation in water temperature. Deliverable 4 (Chapter 2) is a section on issues to be considered and criteria to be used when selecting sites for temperature monitoring. These criteria will serve as a guide for future temperature related research and application of temperature monitoring at regional and national levels. Deliverable 5 (Chapter 3) is the Terms of Reference for the long-term temperature programme (jointly written with Dr Rivers-Moore, and contributed to by Dr Harding). iii iv Table of Contents CHAPTER 1: LITERATURE REVIEW ................................................................ 1 1. Introduction ............................................................................................................. 1 1.1. Spatial variation in water temperature .............................................................. 2 1.2. Temporal variation in water temperature ......................................................... 3 1.3. The importance of water temperature in aquatic ecosystems .......................... 4 1.4. Rivers versus “non-riverine wetlands” .............................................................. 5 1.5. South African examples ................................................................................... 6 2. Measuring water temperature in aquatic ecosystems ......................................... 7 2.1. In situ measurements ....................................................................................... 7 2.2. Modelling water temperature ............................................................................ 9 2.3. Predicting historical or natural temperature regimes ...................................... 11 3. Anthropogenic factors that modify water temperature ..................................... 11 3.1. Thermal discharges ........................................................................................ 11 3.1.1. Heated power station discharges ..................................................... 12 3.1.2. Heated industrial discharges ............................................................ 12 3.1.3. Returning irrigation water ................................................................. 12 3.1.4. Groundwater .................................................................................... 12 3.2. Flow modifications .......................................................................................... 13 3.2.1. River regulation ................................................................................ 13 3.2.2. Inter-basin water transfer (IBT) ........................................................ 15 3.3. Modification to riparian vegetation ................................................................. 15 3.4. Climate change and global warming .............................................................. 16 4. Effects of temperature changes on physical and chemical characteristics of water ..................................................................................................... 18 4.1. Solubility of dissolved oxygen and other gases ............................................. 18 4.2. Chemical reaction rates and toxicity .............................................................. 18 4.3. Microbial activity and reactions ...................................................................... 18 5. Biological effects of temperature changes on aquatic organisms and ecosystems ..................................................................................................... 19 5.1. Primary production ......................................................................................... 20 5.2. Geographical distribution and community structure ....................................... 20 5.3. Trophic interactions ........................................................................................ 21 5.4. Metabolic rate ................................................................................................. 21 5.5. Growth rate .................................................................................................... 22 5.6. Food and feeding habits ................................................................................. 23 5.7. Reproduction, development rates and life histories ....................................... 23 5.7.1. Eggs and fecundity........................................................................... 25 5.7.2. Emergence ....................................................................................... 25 5.7.3. Spawning ......................................................................................... 26 v 5.8. Movements and migrations ............................................................................ 29 5.9. Tolerance to parasites and diseases ............................................................. 31 6. Assessing the effects of temperature changes on aquatic organisms ............ 31 6.1. Field methods – in situ measurements .......................................................... 32 6.1.1. Tolerance ranges derived from the Rivers Database ....................... 33 6.1.2. Tolerance ranges derived from the Biobase .................................... 36 6.2. Laboratory methods – estimation of thermal tolerance of aquatic organisms ..................................................................................................... 36 6.3. Sublethal effects ............................................................................................. 38 6.4. Behavioural preferences and avoidance ........................................................ 38 7. Water temperature guidelines for the protection of aquatic ecosystems ........ 39 7.1. South Africa – water temperature in the Reserve .......................................... 39 7.1.1. Setting the benchmarks if observed data is available ...................... 40 7.1.2. Rapid Reserve – low confidence assessment (no observed data available) .......................................................................................... 41 7.1.3. Intermediate Reserve – medium confidence assessment ............... 41 7.1.4. Comprehensive Reserve – high confidence assessment ................ 41 7.1.5. Present state classification ............................................................... 41 7.2. Australia and New Zealand ............................................................................ 42 7.2.1. Biological and ecological effects data .............................................. 42 7.2.2. Reference system data .................................................................... 42 7.2.3. Predictive
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