Patterns of growth, brooding and offspring size in the invasive mussel Sinanodonta woodiana (Lea, 1834) (Bivalvia: Unionidae) from an anthropogenic heat island

Growth patterns of the pan‐European freshwater mussel, Anodonta anatina (Linnaeus, 1758) (Bivalvia: Unionidae), vary with sex and mortality in populations

“…This indicates that females presented a higher tendency for the post-maturation growth than males. Published information on sex-specific growth of unionids creates an inconsistent picture, with some papers reporting that females reach larger sizes than males (Labecka & Czarnoleski, 2019;Zieritz & Aldridge, 2011) and others indicating no apparent size differences among sexes (Dudgeon & Morton, 1983;Reis & Araujo, 2016).…”

“…Following Haukioja and Hakala (1978), the annual rings deposited on shells were used to assess the age of the mussels (years). This technique was successfully used in previous works on mussels, including the authors' research (Czarnoleski et al, 2003(Czarnoleski et al, , 2005Labecka & Czarnoleski, 2019;Müller et al, 2015), though note that it can underestimate the age of the oldest mussels that slow down growth (Haag & Commens-Carson, 2008;Neves & Moyer, 1988). Our study did not aim at absolute values of mussel longevity, so any potential underestimations of these values (if any) would affect all our population datasets, and thus not change the nature of cross-population relationships that were studied.…”

“…A two-parameter Bertalanffy's formula L ( t ) = L max ( 1 − e − kt ) was used to find a mathematical representation of growth curve trajectories of female and male mussels in each population (Bertalanffy, 1957;Czarnoleski et al, 2003Czarnoleski et al, , 2005Labecka & Czarnoleski, 2019 and were expressed by scores of extracted principal components.…”

“…Classic life history models (Stearns, 1992) predict that such a difference in the prevalence of parasites should select females for earlier maturation, resulting in a smaller asymptotic size in females versus males. Yet, with reference to the life history model of Heino and Kaitala (1996), additionally supported by empirical evidence for Sinanodonta woodiana mussels (Labecka & Czarnoleski, 2019), we considered that (iii) gill-brooding might select females for an increased allocation to post-maturation growth, leading to a larger asymptotic size in females versus males.…”

“…Another notable aspect of unionids’ life strategy is an incomplete cessation of somatic growth after maturation. Consequently, mature individuals continue alternated allocation to growth and reproduction even up to the end of their lives, which results in so‐called indeterminate growth (Kozlowski, 1996; Kozlowski & Uchmański, 1987; Labecka & Czarnoleski, 2019). The indeterminate growth strategy has evolved in many other species of molluscs, and also in nematodes, annelids, crustaceans, insects, fish, amphibians, reptiles, and plants, but its adaptive value is vague (Stearns, 1992).…”