Distribution pattern, density and growth of the stout razor clam Tagelus plebeius in a South-west Atlantic estuarine system

Abstract

The population biology of the stout razor clam Tagelus plebeius is poorly understood, despite the species' current wide distribution, and the potential use of its Holocene shell deposits to infer past environmental and ecological conditions. This study investigates distribution and growth pattern of T. plebeius in the south-western Atlantic Mar Chiquita Coastal lagoon (37°32′S 57°19′W), Argentina. The population includes the oldest individuals (up to 27 years) reported so far with shell length up to 77.9 mm. A von Bertalanffy model with L∞ = 67.60 mm (95% CI = 64.55; 70.64), k = 0.181 year−1 (CI = 0.142; 0.218), and t0 = −0.77 (CI = −1.46; −0.08) best described their individual growth for the whole population. The higher density, growth rate k, t0 and maximum age and lower L∞ were in the low intertidal rather than in the medium intertidal, but there were no differences in density and age between medium and high intertidal. Given the results and the current knowledge on the effects of different factors influencing this species, we conclude that the distribution pattern and shell growth observed in our study reflect a response to metabolic necessities in combination with a strong influence of biological interactions.

Growth changes of the stout razor clam Tagelus plebeius (Lightfoot, 1786) under different salinities in SW Atlantic estuaries

“…Thus, differences in growth parameters are not related to temperature. A previous study in MC showed somewhat different values for Tagelus plebeius k and L∞ (k = 0.181, L∞ = 67.60, Lomovasky et al, 2016) when compared with the present study. Nevertheless, these differences may be due to the use of clams pooled from different locations along the salinity gradient and with ages ranging from 0 to 27 years old, while the range of ages in this study was from 3 to 17.…”

“…Sampling of abiotic variables were carried out in the medium intertidal level (following Lomovasky et al, 2016), where along the semidiurnal tide cycle the water covers when flooding and uncover when ebbing in every tidal cycle. To describe salinity and to verify the patterns reported in the literature (Piccolo and Perillo, 1997;Reta et al, 2001;Isacch et al, 2006), water samples were taken monthly or bimonthly depending on logistical constrains and salinity was measured with a handheld refractometer.…”

“…Tagelus plebeius forms annual internal shell growth bands (Lomovasky et al, 2005;Lomovasky et al, 2016) represented by opaque growth bands (fast growth) and translucent growth lines (slow growth; see Lomovasky et al, 2016 for details) allowing the determination of clam age and development of the corresponding growth models as size-age curves (following Richardson, 2001). Each left shell was embedded in polyester resin, sectioned along the maximum H growth axis using a saw with a diamond blade and the cross-sections were polished on lapidary wheels using sandpaper of 400, 600, 1200, 2500 and 4000 grade (following Lomovasky et al, 2016). The number of translucent internal growth lines (Jones et al, 1990) was counted to assess the age (years) of each individual using a stereo microscope (following age validation made by Lomovasky et al, 2016).…”

“…Each left shell was embedded in polyester resin, sectioned along the maximum H growth axis using a saw with a diamond blade and the cross-sections were polished on lapidary wheels using sandpaper of 400, 600, 1200, 2500 and 4000 grade (following Lomovasky et al, 2016). The number of translucent internal growth lines (Jones et al, 1990) was counted to assess the age (years) of each individual using a stereo microscope (following age validation made by Lomovasky et al, 2016). From the growth models commonly used for bivalves (e.g., Cruz-Vásquez et al, 2012), only Von Bertalanffy (1938) and Logistic (Ricker, 1975) could be statistically compared.…”

Responses of the mussel Brachidontes rodriguezii to aerial exposure: implications on growth and physiological condition

“…Our results suggest that shell growth of B. rodriguezii exhibited a considerable seasonality, probably due to the increment of food availability and water temperature. Other molluscs from the region like Zidona dufresnei (Donovan, 1823) (Giménez et al 2004), the wedge clam Donax hanleyanus Philippi, 1847 (Herrmann et al 2009), and the razor clam Tagelus plebeius (Lightfoot, 1786) (Lomovasky et al 2018), exhibit the same growth pattern, showing a greater increase in shell length when water temperature was higher.…”