Methods for analysing marine and estuarine benthos: Laboratory processing

Transcription

1 Methods for analysing marine and estuarine benthos: Laboratory processing Dr Steve Jarvis & Nigel Proctor Institute of Estuarine & Coastal Studies, University of Hull

2 SAMPLING

3 SAMPLING PROCESSING

4 SAMPLING PROCESSING ANALYSIS

5 Laboratory Processing Sieving Health & Safety Extraction Identification Quality Control Data input

6 Sieving Why (re-)sieve? Reduces volume and storage space Replaces fixative with alcohol (IMS) Better long-term storage Health & safety if sorting immediately Meiofauna Not usually sieved in field Transfer to IMS preferable

7 Quality control Quality of sample Sieving Tap water - moderate flow - puddling Meiofauna - more robust Quality of data No spillage No cross-contamination Random checks Labelling Documentation

8 Sieving Health & safety ventilation eye protection gloves alcohol (fire risks)

9 Extraction (Sorting) Stain (Rose Bengal) Split into size fractions If appropriate. Not required for meiofauna Remove light fraction Swirl and decant - white tray and magnifier - remove with forceps Examine heavy fraction for epifauna and heavyweights

10 Extraction (Sorting) Meiofauna Stain (as with macrofauna) Can also swirl and decant (especially sandy samples) Usually use Ludox adjusted to specific gravity stir and stand for 1 hr (x 3-4) or centrifuge remove with pipette

11 Extraction (Sorting) Quality control Random checks and regular crosschecking Retain residue Labelling 0.5 mm - use stereo microscope Health & safety Adequate ventilation These apply to meiofauna also

12 Identification

13 Identification

14 Identification Why? Yar Lagoon Survey J/1/11/0232 BRAY-CURTIS SIMILARITY T79C N8A S8A S2A N64B N8B S2C 0B S8C 0A S64B S64A S8B N64C S64C S32C S32B T79B N8C T79A 0C N2C N2A S2B N2B N64A S32A N32C N32A N32B N2A N2B N2C N8A N8B N8C N32A N32B N32C N64A N64B N64C S2A S2B S2C S8A S8B S8C S32A S32B S32C S64A S64B S64C 0A 0B 0C T79A T79B T79C

15 Identification - why? Comparability Spatial Temporal Ecology Function Structure

16 Identification - why? Comparability Spatial Temporal Ecology Function Structure Taxonomy - the vocabulary of ecology

17 Identification How?

18 Identification - how? Keys -books Often outdated Nomenclatural changes New species New records Not available for novel faunas

19 Identification - how? Keys - periodicals Not easy to keep up to date with publications about 40 relevant journals ZR expensive Keys -www Updated (in theory)

20 Identification - how? Techniques dissection stains slide mounts e.g. parapodia, nematodes clearing (lactic acid, lactophenol)

21 Identification - how? Meiofauna no dissection for nematodes dissect harpacticoids at first

22 Identification

23 Identification

24 Identification

25 Identification - how? Health & Safety eyes needles, scalpels & chemicals

26 Identification - how? Problems quality of specimens damaged in sieving or preservation (autotomy: acid) poor preservation juveniles (mesh size) polymorphism regeneration

27 Identification - how? Problems - meiofauna size: manipulation & dissection quality of specimens not often damaged in sieving juveniles (always a problem) polymorphism sexual polymorphism regeneration does not apply

28 Identification - how? Quality Control internal consistency communication reference collection - including sketches & microslides labelling documentation

29 Identification - how? Quality Control external checks museum experts NMBAQC ring tests own sample tests whole sample tests meiofauna not covered

30 Sediment analysis

31 Sediment analysis Why? Particle size is one of the principle controlling factors of benthic community structure Track changes in the physical environment brought about by changes in hydrodynamics etc

32 Sediment analysis How? Dry sieving stack of sieves separates particles into size classes (0.5 phi) Sub 63 micron fraction analysed by laser diffraction Quality control NMBAQC

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34 Biomass

35 Biomass Why? Provides information on energetics of a community Benthos is fundamental part of the food chain. Biomass measurements can indicate how important the community is as food for fish and birds.

36 Biomass How? Microbalance weighing down to 4 d.p. (g) Blot dry method Conversion factors to convert to AFDW

37 Biomass QC Cross-checking Balance calibration NMBAQC