Filamentous Freshwater Algae of the ACT, a preliminary list

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Contents Introduction 3 Chapter 1: A year at the causeway at Lower Tuggeranong Creek 5 Table 1. Water Quality and Algal Occurrence 5 Chapter 2: Tolerant and sensitive freshwater algae 7 2a. Sensitivity of Filamentous Algae in ACT Collections. 7 Table 2. Listing of Algae for habitat sensitivity 8 2b. Using algae to add to Water Condition data. 9 Table 3. Growth Rating of Algae 11 Table 4. Tolerance Rating of Algae 11 Chapter 3: Examples of the filamentous algae of the ACT 13 3a. The Riparian Cyanoprokaryota in the ACT 13 3b.Some Chlorophyta of ACT waterways 17 3c. Some Charophyta, other than stoneworts, in ACT waterways 21 3d. Other notable Filamentous Algae in ACT waters 24 References 26 Appendix 1: Specimens collected in connexion with this survey and held by the author. 27 Appendix 2: Records of recent collections of filamentous algae in the Upper Murrumbidgee Catchment Area 32 Table 1a-d. Cyanoprokaryota 33 Table 2. Rhodophyta 34 Table 3. Bacillariophyceae 34 Table 4. Xanthophyceae 34 Table 5a-e. Chlorophyta 34 Table 6a-b Charophyta 36 2
INTRODUCTION Filamentous algae in waterways are often treated as bad organisms, the cause of ‘pollution’ in a cascade or on the concrete spillway of a Gross Pollution Trap. They may well be less than aesthetically pleasing to view. They may confront the nose. They may be hazardous to walk on. But they occur as a symptom, not the cause of problems in riparian systems. And frequently they are not even that, just an unfamiliar (to the perceiver) seasonal phenomenon or a normal function of the system. This dissertation is a defence and a clarification of the good and the bad filamentous algae in the ACT and adjacent waterways. There is a description of the annual cycle of filamentous algal phenomena and correlation to water quality data at one of those causeways where their presence is always noted. A proposal for a tolerance scale for filamentous (visible) algae, similar to the SIGNAL Score for Macroinvertebrates is put forward. And, using the records of collections over the last few years, there is a first attempt at a local listing of taxa and occurrences. ‘Filamentous Algae’ is a carpet-bag term for numerous groups of photosynthetic organisms with little differentiation of anatomy commonly encountered in riparian habitats. Most people, including many aquatic environmental scientists, assume that ‘filamentous algae’ is enough to describe the many and varied manifestations of these organisms. There are also attitudes and assumptions that tend to regard the presence of filamentous algae as indications of disturbance at least and eutrophication at worst. Filamentous algae are rarely truly planktonic. They live attached to structures in the waterways they inhabit. They form rafts and submerged pontoons in the water column when free-floating. Their filaments include many more than 20 cells, and may be branched or fasciculate to increase bulk. There are Cyanoprokaryota, organisms with cells that are bacterial in structure, physiology and reproduction. These are commonly referred to as blue-green algae, or a little more appropriately as cyanobacteria. Many of these are not visible as individual filaments, but rather form encrustations, sheets or gelatinous structures readily visible with the naked eye. There are organisms that belong to the Rhodophyta. They demonstrate a reproductive cycle with a tetrasporic phase and a sexual phase where the donor or male propagules are non-motile single cells. They also have blue and red biliproteins as their subsidiary photosynthetic pigments, along with Chlorophyll A. A few members of the brown pigmented aquatic photosynthetic organisms with siliceous skeletons form large enough aggregations to be noticeable in the riparian environment. These are usually classified as diatoms (Bacillariophyceae) Likewise there are a few, but common, representatives of the group called Golden Green Algae (Xanthophyceae), although the most visible ones are referred to as velvet moss. The most numerous and well represented groups are those usually referred to as the Green Algae. The group which shows physiological and reproductive affinity with 3
Page 1: Filamentous Freshwater Algae of the
Page 5 and 6: Chapter 1. A year at the causeway o
Page 7 and 8: Chapter 2: Tolerant and Sensitive F
Page 9 and 10: See below for a proposal for a SIGN
Page 11 and 12: Table 3: Growth Rating of Algae: Sc
Page 13 and 14: Chapter 3: Examples of the filament
Page 15 and 16: Microcoleus mats in a Gross Polluti

Filamentous Freshwater Algae of the ACT, a preliminary list

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