FRESHWATER INVERTEBRATES
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FRESHWATER INVERTEBRATE RECORDER’S REPORT ADRIAN CHALKLEY Various family health problems have meant very little recording for me this year so I am using my report to begin a review of the current state of knowledge of Suffolk freshwater invertebrates which I hope to continue in future editions of Transactions. It is not a bad idea, as the King said to the White Rabbit, to “Begin at the beginning and go on till you come to the end: then stop.” Hence we shall start with the freshwater zooplankton, concentrating on the Cladocera or Waterfleas. Zooplankton, its role within aquatic habitats and Suffolk recording A major component of aquatic systems worldwide the zooplankton forms the base layer of the food web in pond, lake or river. These tiny creatures support the higher invertebrates, fish and, indirectly, the birds such as the Bittern for which our wetlands are perhaps better known. Recording the zooplankton therefore has an obvious importance but also there are difficulties to be overcome. All zooplankton are tiny and identification to species level needs the use of microscopes and specialised keys which are not always easily available and can be complex to use. We can divide the zooplankton into four main groups: Protists (Protista), Rotifers (Rotifera), Copepods (Crustacea: Copepoda) and Cladocerans (Crustacea: Cladocera). Protists and Rotifers The majority of Protists are truly microscopic and not easy to describe or classify but may be thought of as comprising the single celled algae, the slime moulds and the protozoa. This places us at the evolutionary boundary separating the plant and animal kingdoms, indeed some of the protozoa exhibit characteristics of both. The Rotifers are microscopic animals mostly less than 1 mm long and many less than a tenth of that size, they are present in all types of aquatic environments; in open water, mud, moist sand, damp moss and aquatic vegetation. Identification of both Protists and Rotifers to even group level is not easy and to species requires specialist knowledge. This means there are practically no records on my county database. Copepods The current state of recording of Copepods is, unfortunately, the same as Protists and Rotifers. Although they are very commonly found when sampling freshwater, the complexity and time required to record to species level means that no attempt has been made to analyse the county fauna as yet. Copepods inhabit both marine and freshwater systems and can be found at almost all altitudes, longitudes and latitudes. Their recently estimated species diversity is around 13,000 at a global scale with 2,814 representatives in lakes and ponds (Boxshall & Defaye, 2007). They are thought to have originated in marine environments and colonized freshwater afterwards (Huys & Boxshall, 1991; Boxshall & Jaume, 2000). Whilst the county database has little to say to us about the composition and distribution of these first three types of zooplankton the author welcomes any records that may be sent in by those with the necessary specialist knowledge and interest to contribute.
Trans. Suffolk Nat. Soc. 48 (2012)