Size assessment in polychaete worms—application of morphometric correlations for common North Atlantic taxa

Abstract

Body size is a basic animal feature that defines its functioning in multispecies assemblages. Polychaetes are numerically dominant components of marine macrobenthos, playing a key role in benthic productivity. They are also the most problematic group regarding body‐size assessments due to common fragmentation of fragile bodies during sample processing that inhibits direct assessments of their size and biomass. Here, we present quantified relationships that allow an estimation of the total‐body length based on morphometric features (widths of thoracic chaetigers) that remain intact after standard macrobenthic sample treatment. The best‐fitted regression equations (p < 0.001, r from 0.41 to 0.99) were selected for 28 polychaete families, six orders, two infraclasses, and one subclass based on the measurements on 3580 complete individuals collected in the North Atlantic (Norwegian and Spitsbergen fjords and continental margin). In Capitellidae, Cirratulidae, Oweniidae, and Trichobranchidae, the shapes of the relationships differed among dominant species/genera, and so, specific formula was proposed. The method has been applied to assess the size spectra of macrozoobenthos based on 18 van Veen grab samples collected at six stations in two Spitsbergen fjords. The percentage contribution of complete individuals in polychaete biomass and abundance in size classes varied between 0% and 43%, with the lowest percentages noted in two dominant families—Cirratulidae and Lumbrineridae. The presented method is likely to be widely applied in studies requiring polychaete individual size assessments (e.g., benthic biomass size spectra, population dynamics, and secondary production).

Organic Carbon Origin, Benthic Faunal Consumption, and Burial in Sediments of Northern Atlantic and Arctic Fjords (60–81°N)

“…Five hundred randomly selected meiofaunal nematode individuals per sample were measured using semi‐automated image analysis method (Mazurkiewicz et al, ). Morphometric relationships were used to assess body length in damaged polychaetes (Górska et al, ). For macrofauna taxa with over 250 specimens per sample, a subsample of 200 randomly picked individuals was measured.…”

Seasonal constancy (summer vs. winter) of benthic size spectra in an Arctic fjord

“…For macrofauna-body shapes were matched with geometric figures (Hillebrand et al 1999; Online Resources 1 Table ESM2). The total lengths of fragmented polychaetes (needed for the individual biovolume estimation) were calculated with use of regression formulas based on relationships between widths of selected chaetigers and animal lengths (Górska et al 2019). WM was calculated by multiplying the biovolume by a specific gravity factor of 1.13 (Andrassy 1956).…”

Biogenic Silver Nanoparticles (AgNPs) from Marphysa moribidii Extract: Optimization of Synthesis Parameters

“…These polychaetes were categorized based on their body width: Class I (3-5 mm), Class II (6-8 mm), and Class III (9-11 mm). For each polychaete, the body widths of the first seven chaetigers were measured and expressed in mm (Górska et al, 2019). It should be noted that the width of chaetigers does not include parapodia or bristles.…”