Methods to study organogenesis in decapod crustacean larvae. I. larval rearing, preparation, and fixation

Abstract

Crustacean larvae have served as distinguished models in the field of Ecological Developmental Biology (“EcoDevo”) for many decades, a discipline that examines how developmental mechanisms and their resulting phenotype depend on the environmental context. A contemporary line of research in EcoDevo aims at gaining insights into the immediate tolerance of organisms and their evolutionary potential to adapt to the changing abiotic and biotic environmental conditions created by anthropogenic climate change. Thus, an EcoDevo perspective may be critical to understand and predict the future of organisms in a changing world. Many decapod crustaceans display a complex life cycle that includes pelagic larvae and, in many subgroups, benthic juvenile–adult stages so that a niche shift occurs during the transition from the larval to the juvenile phase. Already at hatching, the larvae possess a wealth of organ systems, many of which also characterise the adult animals, necessary for autonomously surviving and developing in the plankton and suited to respond adaptively to fluctuations of environmental drivers. They also display a rich behavioural repertoire that allows for responses to environmental key factors such as light, hydrostatic pressure, tidal currents, and temperature. Cells, tissues, and organs are at the basis of larval survival, and as the larvae develop, their organs continue to grow in size and complexity. To study organ development, researchers need a suite of state-of-the-art methods adapted to the usually very small size of the larvae. This review and the companion paper set out to provide an overview of methods to study organogenesis in decapod larvae. This first section focuses on larval rearing, preparation, and fixation, whereas the second describes methods to study cells, tissues, and organs.

Larval Development of Non-Insect Arthropods: Metamorphosis and Sexual Differentiation

“…This chapter focuses on larval metamorphosis, sex determination, and sexual differentiation in non-insect arthropods, especially in decapod crustaceans and spider chelicerates. Insects have long been the frontrunners in the study of these phenomena in arthropods, however, new emerging methods such as next-generation sequencing, 3D and high-resolution imaging techniques [120,121], and genome editing methods [122][123][124][125] are opening the door for every non-model species. It is of great benefit to the wealth of available knowledge of insects.…”

Ontogeny of osmoregulation of the Asian shore crab Hemigrapsus sanguineus at an invaded site of Europe

“…Hence, given the realized invasion of E. sinensis , which includes the Baltic Sea, the osmoregulatory pattern reported in this paper is indicative of the strong potential of H. sanguineus to establish coastal populations in the newly invaded areas. Whether such full potential is realized over the full life cycle will depend on other factors, such as temperature, which is known to modulate OC in crustaceans ( Torres et al ., 2021b ) and drive salinity tolerance in the larvae of H. sanguineus ( Epifanio et al ., 1998 ). Hence, whether the full potential is currently realized will depend on latitude, with those local populations present at lower latitude being nearer such potential.…”

“…Experiments with adults were based on field-collected individuals. Experiments with larvae and first stage juveniles were run using standard methods of larval rearing ( Charmantier et al ., 2002 ; Torres et al ., 2020 , 2021b ). Larvae were reared in filtered aerated natural seawater in groups of 50 individuals in 500 ml glass bowls (density: 0.1 larva ml −1 ) in a temperature-controlled room at 24°C, 12:12 h light:dark cycle.…”

Temperature-mediated developmental plasticity in winter and summer larvae of Palaemon serratus

“…The rostro-telson length of 30 newly hatched larvae from each clutch was measured (Campillo, 1979). For each clutch, 3 groups of 104 larvae were distributed in three conical vessels, with filtered seawater at 30 ppt of salinity (± 4), at a density of 100 larvae per L (Reeve, 1969b;Torres et al, 2021). The water was initially at the same temperature as for the maintenance of the females, and then the conical vessels were distributed to 3 incubators (temperature ± 0.3°C, regulated by a TK700 cooling unit by TECO), with photoperiod 12: 12 (L: D) and constant thin aeration.…”