Growth ofStegophiura nodosa(Echinodermata, Ophiuroidea) in the Pechora Sea

Abstract

The brittle star Stegophiura nodosa is one of the most abundant ophiuroid species living in Arctic seas and serves as a food resource for demersal fish. The study of autecological and biological patterns of S. nodosa is important for understanding the species reaction to environmental change. The growth features and growth rate of this brittle star from the Pechora Sea were estimated using the Gompertz equation as the basic mathematical model and compared with Bertalanffy equation parameters. Individual age was evaluated by counting the ring-shaped growth marks in the calcite structure of the animal's vertebral ossicle, where each visible ring was considered to be an annual growth mark. The calculations indicated: the theoretical limiting radius of the brittle star's ossicle (R∞) averages 318 ± 18 μm, and the exponential deceleration of the specific growth rate (g) is found to be 0.46 ± 0.02. The initial hidden growth marks were found to vary from 1–3, and the maximum lifespan of S. nodosa in the Pechora Sea (SE of the Barents Sea) is evaluated to be 9–10 years.

Effect of different substrates on growth and biochemical composition of the ornamental “red cherry” caridean shrimp, Neocaridina davidi (Atyidae)

“…davidi were compared among different substrates using sigmoid growth functions. These models have become popular in recent decades and have been successfully applied to other crustacean species (Aragón‐Noriega, 2017), ophiuroidea (Stratanenko & Denisenko, 2020), fish (Hart & Chute, 2009; Kielbassa et al, 2010; Wang & Ma, 2016), birds (Brunner et al, 2021; Svagelj et al, 2019), mammals (Thorley & Clutton‐Brock, 2019) and even in plants (Ukalska & Jastrzębowski, 2019). Here, it was found that N .…”