Mesh selection of copepodite and nauplius stages of four calanoid copepod species

Nichols, James Hastings; Thompson, A. B.

doi:10.1093/plankt/13.3.661

Cited by 128 publications

(72 citation statements)

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“…However, as indicated from the 95% CI, the ratio of 50 μm mesh net abundance to water bottle abundance did not significantly differ from 1 (except in one case). The smallest of the 30 NI/NII we measured were 50 μm wide and the average was 62 μm; individuals of these sizes are captured by a 50 μm mesh net with an efficiency of ~50 and 90% respectively (Nichols & Thompson 1991). Losses of NI/NII are likely to be small, but would lead to some overestimation of mortality across egg-NI/NII stages and underestimation across NI/NII-NIII/NIV stages.…”

Section: Stage Abundancementioning

confidence: 89%

Spring mortality of the cyclopoid copepod Oithona similis in polar waters

Hirst¹,

Ward²

2008

Mar. Ecol. Prog. Ser.

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Section: Stage Abundancementioning

confidence: 89%

Spring mortality of the cyclopoid copepod Oithona similis in polar waters

Hirst¹,

Ward²

2008

Mar. Ecol. Prog. Ser.

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“…A mesh aperture of 200 m retains >95% of Calanus finmarchicus copepodite stage CI and 100% of CII and later stages, but retains only a small proportion of naupliar stages (Nichols and Thompson, 1991). The nets were towed vertically from around 10 m above the sea-bed to the surface at a speed of 30-40 m min 1 , except at Weathership M, where sampling was confined to the upper 1600 m. The zooplankton samples were preserved in 4% neutralized formalin until later analysis in the laboratory ashore.…”

Section: Field Samplingmentioning

confidence: 99%

Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

HEATH¹

2004

ICES Journal of Marine Science

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. 2000. Comparative analysis of Calanus finmarchicus demography at locations around the Northeast Atlantic.Standardized time-series sampling was carried out throughout 1997 at seven locations around the Northeast Atlantic to investigate regional variations in the seasonal demography of Calanus finmarchicus. Sites ranged from an inshore location in the North Sea, where C. finmarchicus formed only a small component of the zooplankton (<10 mgC m 2 during spring and early summer), to the shelf south of Iceland, and Weathership M in the Norwegian Sea, where the species dominated the zooplankton (>2000 mgC m 2 during spring and summer). The internal consistency of the demographic time series from each site was investigated by three partial models of life-cycle processes. In general, the demography of late copepodites could be accounted for by a relatively simple forecast model of stage development and diapause. However, there was a large discrepancy between nowcast estimates of egg production based on female abundance, temperature, and chlorophyll, and hindcast simulations of the egg production required to account for the observed abundance of early copepodite stages. The results point to a gap in our understanding of seasonal variations in rates of egg production and/or survival of nauplii. Overall, the population sampled at Weathership M appeared to be reasonably self-contained, but all other sites were reliant on invasion of overwintered stock in spring. At least two generations were observed at all but one site, but the extent to which these were generated by discrete bursts of egg production varied between sites and seemed to be partly dependent on the proximity to an overwintering location.

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“…Note: (1) cutoffs for the 50/Taxon, 150/Sample, and 200/Taxon methods were based on counts of broader taxonomic categories than the 100/Species and Double Count methods (see text for further details) and (2) letters in parentheses after the number of individuals counted for each method indicate significant differences between methods. (Gannon 1980;Nichols and Thompson 1991;Johannsson et al 1992). Given these biases, investigators must understand the limitations of their gear.…”

Section: Discussionmentioning

confidence: 99%

A comparative analysis of zooplankton field collection and sample enumeration methods

Mack

Conroy

Blocksom

et al. 2012

Limnology & Ocean Methods

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Understanding differences in zooplankton abundance depends on comparing similar data. Scientists employ numerous methods to collect and count freshwater zooplankton, potentially leading to difficulties when comparing studies. As scant information concerning specific biases exists, we quantified how (1) net mesh size and (2) counting techniques influence zooplankton size and abundance estimates. We compared mesh sizes by collecting zooplankton with four vertically hauled nets differing only in mesh size. We examined mesh‐size effects on filtration efficiency across a suspended sediment gradient by comparing the known (quantified with a flowmeter) and assumed (from site depth) sample volumes. Finally, eight samples were counted with each of four methods to compare estimates of zooplankton abundance among techniques that differ in the minimum number of individuals counted. We found that only 64‐µm mesh nets effectively capture small‐bodied zooplankton (small cladocerans, copepod nauplii, and rotifers, mean size = 0.13−0.30 mm) whereas all nets effectively collected larger‐bodied zooplankton (mean size > 0.48 mm). All three > 100 µm‐mesh nets were > 90% efficient, regardless of suspended solids abundance. In contrast, the 64‐µm mesh net was at best 60% efficient; hence, actual volume sampled must be determined to avoid underestimation. We found counting‐method‐specific shortcomings, particularly for those in which few individuals were counted. We recommend, then, that a moderate number of individuals are counted for many finely resolved taxonomic categories or many individuals are counted for fewer, broader taxonomic categories. Consequently, to directly compare zooplankton densities between studies, scientists need a clear understanding of field collection and laboratory enumeration methods.

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Mesh selection of copepodite and nauplius stages of four calanoid copepod species

Cited by 128 publications

References 0 publications

Spring mortality of the cyclopoid copepod Oithona similis in polar waters

Spring mortality of the cyclopoid copepod Oithona similis in polar waters

Comparative ecology of over-wintering Calanus finmarchicus in the northern North Atlantic, and implications for life-cycle patterns

A comparative analysis of zooplankton field collection and sample enumeration methods

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