Morphometric and molecular identification of individual barnacle cyprids from wild plankton: an approach to detecting fouling and invasive barnacle species

Abstract

The present study used DNA barcodes to identify individual cyprids to species. This enables accurate quantification of larvae of potential fouling species in the plankton. In addition, it explains the settlement patterns of barnacles and serves as an early warning system of unwanted immigrant species. Sequences from a total of 540 individual cypris larvae from Taiwanese waters formed 36 monophyletic clades (species) in a phylogenetic tree. Of these clades, 26 were identified to species, but 10 unknown monophyletic clades represented non-native species. Cyprids of the invasive barnacle, Megabalanus cocopoma, were identified. Multivariate analysis of antennular morphometric characters revealed three significant clusters in a nMDS plot, viz. a bell-shaped attachment organ (most species), a shoe-shaped attachment organ (some species), and a spear-shaped attachment organ (coral barnacles only). These differences in attachment organ structure indicate that antennular structures interact directly with the diverse substrata involved in cirripede settlement.

Species- and stage-specific barnacle larval distributions obtained from AUV sampling and genetic analysis in Buzzards Bay, Massachusetts, USA

“…However, many larvae can influence their horizontal distribution by controlling their vertical position (Nelson, 1912;Knights et al, 2006) and thus affect transport and spatial distributions on bottom habitats. Distributional patterns and behaviors are species-specific, but larvae are difficult to identify with traditional methods (Wong et al, 2014;Chen et al, 2013a; and knowledge on vertical distribution and behavior is lacking for most species.…”

“…Following collection, larvae are traditionally identified to gross taxonomic level. Invertebrate larvae are difficult or practically impossible to identify to species using morphometric methods (e.g., Wong et al, 2014;Chen et al, 2013a for barnacles), and processing time is often prohibitive with intensive sampling . Thus, larvae are often binned into super-specific groupings (e.g., 'bivalves' or 'nauplii') that confound interpretation of results.…”

Collecting and processing thoracican, acrothoracican, and rhizocephalan cirripedes

“…2. A, photoframer made by PCV pipes; B, 25 × 25 cm quadrate taken with photoframer, showing Tetraclita barnacles; C, sampling the abundance of barnacles on seawall from a boat using a photoframer; D, relationship between running mean abundance (± 1 SD) of acorn barnacles T. japonica formosana against number of quadrats (25 × 25 cm) sampled; E, passive plankton trap (Yan et al, 2004) and its internal design (F); G, coned tube trap (Todd et al, 2006) that can sample barnacle larvae when immersed during high tides; H, an integrative trap (Chen et al, 2013b) that can collect barnacle larvae during the swash and immersed period and its internal design (I); J, roof and control roof for rocky shores (Chan and Williams, 2003); K, replicate roofs and control roofs at high and mid-tide levels on a rocky shore. the pipe threads permit closure of the trap and attachment of the internal, removable, plankton net bag (mesh size 100 μm).…”

“…Further experimental studies are needed to establish their efficiency in collecting other species or even other types of barnacle larvae. Chen et al (2013b) further developed an integrative trap that can collect zooplankton during both the submerged and swash periods. The integrative trap consists of two threaded sections of PVC piping (Fig.…”

“…Chen et al (2013a) developed a DNA extraction and PCR protocol that can extract DNA from ethanol-preserved cyprids and identified to species by comparing the DNA barcode of larvae to the adult references.…”