Sclerochronological records and daily microgrowth of the Peruvian scallop (Argopecten purpuratus, Lamarck, 1819) related to environmental conditions in Paracas Bay, Pisco, Peru

Abstract

International audienceWe investigated the rhythm of micro-striae formation in the shell of Argopecten purpuratus and environmental influence on micro-growth increments by monitoring growth over a 98-day period between April and July 2007 under bottom and suspended culture (2m above the bottom) rearing conditions. The transfer of individuals to the study site induced the formation of a notable growth mark that allowed us to count the number of micro-striae formed between transfer and sampling dates. Micro-striae counts showed a deposition rate of one stria per day independent of rearing condition. This result allowed us to analyse the relationships between growth increments and environmental conditions. We therefore examined the deviations between observed growth rates and growth rates predicted from a Von Bertalanffy growth function. Cross-correlation analysis revealed significant correlations, without time-lag, between these deviations and both particulate organic carbon and nitrogen concentrations in the bottom treatment. Additionally, we observed negative correlations with temperature and current speed at this depth with time-lags of 1 and 10 days respectively. In the suspended treatment, we observed a significant negative correlation with temperature, only with a 12-day lag-time. Our results show that growth response to environmental variability is not always instantaneous. This delay can be explained by the time delay over which metabolic processes need to be performed (e.g. digestion, use/movements of reserves, growth, reproduction). Further modeling studies could help to better understand these processes

LIFE HISTORY, ENVIRONMENT AND EXTINCTION OF THE SCALLOPCAROLINAPECTEN EBOREUS(CONRAD) IN THE PLIO-PLEISTOCENE OF THE U.S. EASTERN SEABOARD

“…In these, microgrowth-increment size increases from late winter to reach a summer maximum and then falls to a late fall minimum, succeeded by several months of little or no growth. Over the period in which the largest increments are formed, which is also the time of most rapid overall growth, the number laid down closely corresponds to the number of days elapsed (i.e., the microgrowth increments are 'daily'), as in some other scallop species (e.g., Joll 1988;Clark 2005;Velarde et al 2015). Outside this period, fewer are laid down, such that there is an increasing discrepancy with the number of days elapsed as the time-interval expands.…”

Chronic and severe hypoxic conditions in Paracas Bay, Pisco, Peru: Consequences on scallop growth, reproduction, and survival

“…More recently, high frequency monitoring under neutral (normal) ENSO conditions allowed recording dramatic variations in temperature (Aguirre-Velarde et al, 2015, 2016 and dissolved oxygen concentration (Aguirre-Velarde et al, 2016). Paracas Bay is also affected by the occurrence of milky-turquoise water events, locally known as "aguas blancas", that producers related with increased scallop mortality.…”

“…purpuratus (Thébault et al, 2008;Aguirre-Velarde et al, 2015), suggesting the importance of improving our knowledge on the effect of environmental conditions on scallop productive performance. The present study was carried out to characterize the environmental dynamics in Paracas Bay at a fine temporal scale in order to better identify the variability encountered by the scallops in cultivation and its productive consequences.…”

“…The analysis of the influence of environmental conditions on growth was performed after removing the ontogenic reduction of growth rate (Gulland and Hold, 1959) according to the procedure described in Aguirre-Velarde et al (2015). For this purpose, a weight-based von Bertalanffy growth function (VBGF) was fitted to somatic growth records from size groups 1 and 2 of the bottom treatment (considered as a reference).…”

Bradoriids (Arthropoda) and the Cambrian Diversification

“…In addition, the flat wide marginal rim would also make the shields more effective for flap swimming, with the posterodorsal lobes serving a hydrodynamic function similar to that of the anterior and posterior auricles of the Peruvian scallop Argopecten purpuratus [123]. Furthermore, the overhang of the dorsal margin by the anterior lobe in Cambroarchilocus tigris gen. nov. sp.…”