Elsevier

Journal of Sea Research

Volume 133, March 2018, Pages 81-87
Journal of Sea Research

Catch me if you can: Comparing ballast water sampling skids to traditional net sampling

https://doi.org/10.1016/j.seares.2017.03.009Get rights and content
Under a Creative Commons license
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Highlights

  • Shipboard sampling skids were tested as an alternative to traditional plankton nets.

  • Untreated ballast water samples were analyzed in parallel by many analytic methods.

  • Some differences were detected between samples collected using different devices.

  • Many detected differences could not be explained by sampling device.

Abstract

With the recent ratification of the International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004, it will soon be necessary to assess ships for compliance with ballast water discharge standards. Sampling skids that allow the efficient collection of ballast water samples in a compact space have been developed for this purpose. We ran 22 trials on board the RV Meteor from June 4–15, 2015 to evaluate the performance of three ballast water sampling devices (traditional plankton net, Triton sampling skid, SGS sampling skid) for three organism size classes:  50 μm,  10 μm to < 50 μm, and < 10 μm. Natural sea water was run through the ballast water system and untreated samples were collected using paired sampling devices. Collected samples were analyzed in parallel by multiple analysts using several different analytic methods to quantify organism concentrations. To determine whether there were differences in the number of viable organisms collected across sampling devices, results were standardized and statistically treated to filter out other sources of variability, resulting in an outcome variable representing the mean difference in measurements that can be attributed to sampling devices. These results were tested for significance using pairwise Tukey contrasts. Differences in organism concentrations were found in 50% of comparisons between sampling skids and the plankton net for ≥ 50 μm, and ≥ 10 μm to < 50 μm size classes, with net samples containing either higher or lower densities. There were no differences for < 10 μm organisms. Future work will be required to explicitly examine the potential effects of flow velocity, sampling duration, sampled volume, and organism concentrations on sampling device performance.

Keywords

Ballast water sampling system
Compliance monitoring
IMO D-2 standards
Non-indigenous species
Shipping

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