Age and growth in the Australian freshwater mussel, Westralunio carteri, with an evaluation of the fluorochrome calcein for validating the assumption of annulus formation

Abstract

Growth and longevity of freshwater mussels (Unionida) are important for defining life-history strategies and assessing vulnerability to human impacts. We used mark-recapture and analysis of shell rings to investigate age and growth of the hyriid, Westralunio carteri, at 5 sites in southwestern Australia. We tested the utility of the in situ marker calcein for validating the assumption of annulus formation in adults. Calcein was incorporated into the shells of all recovered individuals, but it provided an interpretable reference mark in only 4 of 16 individuals. These 4 individuals produced 1 shell ring subsequent to the mark, supporting the assumption of annulus production during the austral winter. Maximum age ranged among populations from 36 to 52 y and maximum size ranged from 72.9 to 82.8 mm. Mean age and length did not differ between sexes, and growth trajectories differed between sexes at only 1 site. Estimates of growth measured by the von Bertalanffy growth constant, K, ranged from 0.021 to 0.336 among sites. Estimates from mark-recapture experiments were 20 to 52% lower than values from shell annuli at all sites except 1 where K from shell annuli was ∼½ that estimated from mark-recapture. Both methods showed a positive relationship between K and mean water temperature among sites, suggesting a role of riparian shading in regulating stream temperature, and hence, indirectly influencing mussel growth. Mussel growth and mean N or P concentrations were not related among sites, but total N at the site with highest mussel growth was >2× higher than at any other site. Westralunio carteri is a long-lived, slow-growing bivalve. Maximum age, K, and probable age at maturity (4-6 y) are similar to other slow-growing freshwater bivalve groups. This suite of life-history traits is considered an adaptation for stable aquatic habitats. Therefore, W. carteri can be expected to adapt poorly to human impacts, such as riparian clearing and water extraction, which increase the temporal variability of environmental conditions in streams.

Influence of surrounding land-use on mussel growth and glycogen levels in the St. Croix and Minnesota River Basins

“…Gascho Landis et al (2013) and Gascho Landis & found that while increasing TSS resulted in reduced reproduction, there was no impact on growth rates. Research studies have used growth rates to evaluate changes in food source, inundation frequency, temperature, and release of environmental pollutants (Klunzinger et al, 2014;Negishi et al, 2012Negishi et al, , 2014aFritts et al, 2017). Growth rate has been found to differ between sexes of some mussel species where males often reach a larger maximum size, but this is not true for every species (Haag & Rypel, 2011).…”

Research priorities for freshwater mussel conservation assessment

“…Some long-lived mussel species can persist with infrequent and low recruitment events, even though juvenile survival can be quite low (e.g., Margaritifera auricularia; Prié et al, 2018). Other species require more frequent and even annual recruitment to maintain sustainable populations (Outeiro et al, 2008;Hastie et al, 2010;Klunzinger et al, 2014). Factors leading to low recruitment include juvenile habitat degradation and decreases in the populations of fish hosts (Bolotov et al, 2012).…”

Upstream recolonization by freshwater mussels (Unionoida: Hyriidae) following installation of a fishway

“…The lack of large mussels in the upstream reach during the present survey suggests that there was little or no recruitment before fishway installation 14 years ago. Age‐at‐length measurements for other populations of this species (Klunzinger, Beatty, Morgan, Lymbery, & Haag, ) show that SLs greater than 65 mm are not reached until 15+ years, at which point growth reaches an asymptote, with maximum lengths of 75–80+ mm not reached for 25–50+ years. Mussels ranging from 65–79 mm SL were common downstream of the weir in the mainstem of the river, but the largest individual found upstream was only 64.6 mm SL.…”