Mesh size effects on assessments of planktonic hydrozoan abundance and assemblage structure

Author(s)

Junior, Miodeli Nogueira ^[1] ; Pukanski, Luis Eduardo de M. ^[2] ; Souza-Conceicao, Jose M. ^[3]

Affiliation

^[1] Univ Fed Parana, MPL, Ctr Estudos Mar, Pontal Do Parana - Brazil

^[2] Univ Fed Parana, Programa Pos Grad Zool, Curitiba, Parana - Brazil

^[3] Univ Regiao Joinville, Joinville, Santa Catarina - Brazil

• Document type: Journal article
• Source: JOURNAL OF MARINE SYSTEMS; v. 144, p. 117-126, APR 2015.
• Web of Science Citations: 7

Abstract

The choice of appropriate mesh-size is paramount to accurately quantify planktonic assemblages, however there is no such information available for hydrozoans. Here planktonic hydrozoan abundance and assemblage structure were compared using 200 and 500 mu m meshes at Babitonga estuary (S Brazil), throughout a year cycle. Species richness and Shannon-Wiener diversity were higher in the 200 mu m mesh, while evenness was typically higher in the 500 mu m. Assemblage structure was significantly different between meshes (PERMANOVA, P < 0.05; n = 72 pairs of samples) both regarding taxa and size composition. These discrepancies are due to significant underestimation of small hydromedusae by the coarse mesh, like Obelia spp., young Liriope tetraphylla, Podocoryna loyola and others. Yet, larger taxa like Eucheilota maculata and adult L. tetraphylla were more abundant in the coarse mesh on some occasions and others such as Blackfordia virginica and Muggiaea kochi were similarly represented in both meshes. Overall collection efficiency of the coarse mesh (CE500) was 14.4%, with monthly averages between 1.6% and 43.0%, in July (winter) and January (summer) respectively. Differences between the meshes were size-dependent; CE500 was similar to 0.3% for hydrozoans sizing <0.5 mm, similar to 21% for those between 1 and 2 mm, similar to 56% for those between 2 and 4 mm, and nearly 100% for larger ones, reaching up to 312% for hydrozoans >8 mm in October. These results suggest that both meshes have their drawbacks and the best choice would depend on the objectives of each study. Nevertheless species richness, total abundances and most taxa were better represented by the 200 mu m mesh, suggesting that it is more appropriate to quantitatively sample planktonic hydrozoan assemblages. (C) 2014 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/09880-8 - Long-term flutuations (1963-2003) on the structure and abundance of gelatinous zooplankton (Cnidaria and Thaliacea) on South Brazilian Bight
• Grantee: Miodeli Nogueira Junior
• Support type: Scholarships in Brazil - Post-Doctorate