“…The 18S rDNA gene is one of the most commonly used markers for species identification and delineation due to its conserved and hypervariable regions (V1‐V9) (Kooistra et al., 2010 ; Medlin et al., 1996 ). Previous studies of protist diversity using metabarcoding have used one of the hypervariable short read regions in the 18S rDNA e.g., V1‐V2 and V3, V4, V6, V7‐V8, V8‐V9 or V9 (Amaral‐Zettler et al., 2009 ; Bradley et al., 2016 ; Bukin et al., 2023 ; de Vargas et al., 2015 ; Hadziavdic et al., 2014 ; Hatteranth‐Lehmann et al., 2019 ; Massana et al., 2015 ; Medinger et al., 2010 ; Mohrbeck et al., 2015 ; Piredda et al., 2017 ; Stoeck et al., 2010 ). Until now, most metabarcoding studies of plankton diversity has been assessed using primer pairs that produce fragments lengths <600 bp.…”