Zooplankton processing
Background
LEVEL OF IDENTIFICATION:
For Cladocera (all life stages) and adult Copepoda, identifications are to the species level with the exception of the following genera: Acanthocyclops, Microcyclops, Alona, Camptocercus, Eurycercus, and Ceriodaphnia. For copepodids, Limnocalanus macrurus and Senecella calanoides are identified to species. Epischura copepodids are identified to the genus level. All other copepodids and all nauplii are identified to the order level (Cyclopoida or Calanoida). Harpacticoida are only identified as such. A Leica M205C stereomicroscope is used for this work.
FRACTIONS:
Unless a whole sample count is requested, sub-samples are generated by using a precise starting volume from which carefully measured aliquots are derived using Hensen-Stempel pipettes. Even if the count targets are reached after examining a portion of a sub-sample, the examination of the remaining sub-sample is completed in its entirety. The total fraction analyzed is meticulously noted for each type of immature Copepoda and for each species so that the whole sample density can be extrapolated.
ZEBRA2:
To generate biomass assessments, I use the ZEBRA2 semi-automated processing software. Digital caliper measurements taken off a video monitor attached to a microscope camera are translated into weights based on established length-weight regressions (page 89) for formalin preserved samples.
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For ethanol preserved samples, the client can provide their own length-weight regressions. If this data is not available, sample processing includes counts, identifications to the lowest practical level, and sexing (upon request). This captures community level species and density data, without biomass.
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PYTHON:
Although well known, the ZEBRA2 program (developed in the early 1990s) only produces data files and bench sheets in antiquated formats that are difficult to interpret (i.e., .prn and .dbf). To work around this, I engaged the services of Data Analyst Emily Smenderovac who produced custom Python scripts to my specifications. These automate the population of custom Excel spreadsheets I designed with the measurement and species data from the raw ZEBRA2 files; hence, Python scripts dramatically reduce the amount of manual data entry and also considerably speed up the entire process. These were tailored to specific client data needs, as outlined below.
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ZOOPLANKTON PICTURES:
All projects include a set of high quality digital images taken with a Leica MC170 HD microscope camera, at no added cost. Species (or genera if that is the lowest practical level of identification) encountered during processing will be included.
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Processing Protocols
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Many protocols can be applied, depending upon the study goals. For all protocols, the level of identification outlined above is applied (i.e., generally to species). A rare species scan can be added to any protocol if a full species list is required. In this case, the remaining sample is examined and all the species not included in the count are identified and enumerated within the Comments section of the bench sheet.​ Due to the added processing effort, rare species scans do incur an added cost.
1. Dorset protocol (pages 81-84): this protocol was developed by the Dorset Environmental Science Centre of the Ontario Ministry of the Environment, Conservation & Parks. It is my "default" protocol, unless the client has more specific project goals. The aim is to minimize counts of immature Copepoda and also weed out the dominant species by ensuring that no species accounts for more than 20% of the count. Every individual included in the count is also measured.
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count and measure 15-35 of each type of nauplii (Cyclopoida and Calanoida)
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count and measure 15-35 of each type of copepodid (Cyclopoida and Calanoida)
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the remaining number of individuals, up to the minimum of 240, is divided amongst Cladocera and adult Copepoda. Count and measure 45-60 individuals for a dominant species in a sub-sample.
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identify and enumerate any zebra mussel veligers, Chaoborus and Bythotrephes encountered during the count, and note in the Comments. No measurements need to be taken and the entire sample does not need to be scanned for these species.
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in the Comments section, the genera of the most common Rotifera encountered during the count are noted. A rotifer index between 0 and 5 (0 meaning none present to 5 meaning extreme abundance) is assigned for each sample. [Note that Rotifera counts are generally not included in any protocol and are a very rough assessment only!]
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2. Simcoe Bythotrephes protocol: the Ontario Ministry of the Environment, Conservation & Parks Lake Simcoe Monitoring Branch has a specific protocol which targets the invasive species, Bythotrephes cederstroemii (i.e., spiny water flea).
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measure every Bythotrephes in the sample and record its attributes (sex, instar, stage of fecundity, clutch size, and tail spine morphology) in ZEBRA2
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measure every Mysis and record its sex in ZEBRA2
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all other larger taxa (e.g., Leptodora, mites, etc.) are enumerated in a separate Excel spreadsheet
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The Ontario Ministry of the Environment, Conservation & Parks compiled their own length-weight regressions (page 89) which are incorporated into their custom Python script, written by Emily Smenderovac. This applies to count protocols 1 and 2.
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3. Bowen protocol: another protocol I use extensively is that developed by the Department of Fisheries and Oceans, Great Lakes Laboratory for Fisheries and Aquatic Science in Burlington, Ontario (i.e., GLLFAS). Unlike the above protocols designed by the MECP, only a subset of the count are measured then the average weight is applied to the entire per species count.
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remove Bythotrephes, Mysis, and Cercopagis before splitting the sample with the syringe method. If present, count them ALL but only measure adults and count eggs in 30/species. If a sample is very dense with Bythotrephes, these are removed to a separate gridded tray and only 20% are included in the count (30 measured with eggs also counted).
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minimum count set at 400 (200 if only 1 species is present) OR a maximum of 20% of the starting working volume. Count is evenly divided between Cladocera, mature Copepoda, immature Calanoida, and immature Cyclopoida. Veligers encountered during the count are also included.
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measure 30 each for the zebra mussel veligers, Calanoida nauplii, Cyclopoida nauplii, Calanoida copepodids, and Cyclopoida copepodids, then 50 each for the species of Cladocera and the species of mature Copepoda
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record if the measured animals have eggs (if so, note the number of eggs/animal)
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for loose eggs in the sample, track a maximum of 100 eggs and identify as belonging to Cladocera (neonates included), Cyclopoida, or Calanoida
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The GLLFAS compiled their own length-weight regressions (page 15) which are incorporated into their custom Python script, written by Emily Smenderovac.
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4. Cultus protocol: The Department of Fisheries and Oceans, Cultus Lake Salmon Research Laboratory in BC developed this protocol. Similar to the Bowen protocol, the count is divided between categories but in this case, the target groups are based upon the measurements outlined below, not taxonomic divisions. Also, every individual included in the count is measured.
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minimum count set at 400, with 4 size class targets as outlined below
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50 maximum Copepoda nauplii < 0.6 mm
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100 minimum zooplankton < 0.6 mm
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150 minimum zooplankton >= 0.6 mm and < 1.2 mm
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100 minimum zooplankton >= 1.2 mm
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a whole sample rare species scan for larger taxa is also required
The Cultus Lab required integration with their long-term zooplankton database. A custom Python script, written by Emily Smenderovac, populates Excel spreadsheets which I designed to Cultus' exact specifications with the raw ZEBRA2 measurement and species data. Cultus also has their own set of species codes which I associated to ZEBRA2's species codes. Both sets of codes are shown in their Excel spreadsheets.
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5. Size class protocol: Identical to the above "Cultus protocol", minus the elements specific to Cultus' database (i.e., Cultus species codes and database formatting). Therefore, data is sorted into the 4 size classes outlined under "Cultus".
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6. MFFP/UQAM protocol (Ministère des Forêts, de la Faune et des Parcs in association with l'Université du Québec à Montréal, QC): Only a subset is measured then the average weights are applied to the entire count/species.
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count up to 200 individuals of the same species, or
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count to 1000 individuals as the stopping point, or
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count the entire sample if criteria 1 or 2 are not met
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only 10 individuals/species or immature Copepoda group are measured
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a whole sample rare species scan for larger taxa is also required
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in the Comments section, the genera of the most common Rotifera encountered during the count are listed.
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End Notes
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For all projects, species and density data are provided to the client in an Excel spreadsheet for each sample. An Excel species list is also created per lake or per year (format is at the client's discretion). Protocols using ZEBRA2 add mean lengths, mean weights, and biomass data and also produce a separate Excel measurement file.
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With the aim of being as environmentally responsible as possible, I reduce my generation of waste products by re-using client preservative on a per project basis. To this end, excess waste is strongly discouraged and may incur a surcharge. Please see note at bottom of the page on "Shipping samples".
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I pride myself on providing highly customized solutions to meet any data needs. Although I am most familiar with the above protocols, I can adopt any requested method of processing zooplankton samples to ensure consistency with the work of previous Zooplankton Taxonomists.