A suction pump sampler for invertebrate drift detects exceptionally high concentrations of small invertebrates that drift nets miss

Details

• Journal Title:
  Hydrobiologia
• Personal Author:
  Neuswanger, Jason R. ; Schoen, Erik R. ; Wipfli, Mark S. ; Volk, Carol J. ; Savereide, James W.
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; AFSC (Alaska Fisheries Science Center)
• Description:
  Invertebrate drift is a key process in riverine ecosystems controlling aquatic invertebrate distribution and availability to fish as prey. However, accurately quantifying drifting invertebrates of all sizes is difficult because the fine-mesh nets required to capture the smallest specimens clog easily, which reduces filtration efficiency and measurement accuracy. To address this problem, we developed a gas-powered pump system that delivers 20 m3/hour of river water through nested 80- and 750-μm-mesh nets suspended in the air. We compared 17 pumped samples with those obtained by adjacent, conventional deployment of a 250-μm drift net in a clear-water Alaskan river during both low and high flows. Our drift pump system sampled a geometric mean drift concentration of 467 invertebrates m−3 (maximum 5637 m−3) – eleven times the mean concentration of 42 m−3 estimated using the drift net. Invertebrates ≤ 3 mm long, primarily chironomids, comprised the entire difference between methods. Investigators for whom the drift of 0.5–3 mm invertebrates might be relevant (e.g., those applying foraging models for juvenile drift-feeding fishes) should consider using a pump or similar aerial filtration method to quantify small invertebrate drift, lest they underestimate it by an order of magnitude.
• Keywords:
  Distribution Invertabrates Invertebrate Surveys Invertebrate Surveys
• Source:
  Hydrobiologia 849: 2077–2089
• DOI:
  https://doi.org/10.1007/s10750-022-04849-1
• Document Type:
  Journal Article
• Funding:
  Grant no. NA18NMF4380261
• Rights Information:
  Accepted Manuscript
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:bc28e5e1eb7cac89681b8a5fb11133fe8520f9e05b6719e1e806fd9bc7e1fdeb
• Download URL:
  https://repository.library.noaa.gov/view/noaa/39494/noaa_39494_DS1.pdf
• File Type:
  [PDF - 435.53 KB ]