Larval Development in Tropical Gar (Atractosteus tropicus) Is Dependent on the Embryonic Thermal Regime: Ecological Implications under a Climate Change Context

Abstract

In ectotherm species, environmental temperature plays a key role in development, growth, and survival. Thus, determining how temperature affects fish populations is of utmost importance to accurately predict the risk of climate change over fisheries and aquaculture, critical to warrant nutrition and food security in the coming years. Here, the potential effects of abnormal thermal regimes (24, 28 and 32 °C; TR24, TR28, and TR32, respectively) exclusively applied during embryogenesis in tropical gar (Atractosteus tropicus) has been explored to decipher the potential consequences on hatching and growth from fertilization to 16 days post-fertilization (dpf), while effects on skeletal development and body morphology were explored at fertilization and 16 dpf. Egg incubation at higher temperatures induced an early hatching and mouth opening. A higher hatching rate was obtained in eggs incubated at 28 °C when compared to those at 24 °C. No differences were found in fish survival at 16 dpf, with values ranging from 84.89 to 88.86%, but increased wet body weight and standard length were found in larvae from TR24 and TR32 groups. Thermal regime during embryogenesis also altered the rate at which the skeletal development occurs. Larvae from the TR32 group showed an advanced skeletal development, with a higher development of cartilaginous structures at hatching but reduced at 16 dpf when compared with the TR24 and TR28 groups. Furthermore, this advanced skeletal development seemed to determine the fish body morphology. Based on biometric measures, a principal component analysis showed how along development, larvae from each thermal regime were clustered together, but with each population remaining clearly separated from each other. The current study shows how changes in temperature may induce craniofacial and morphological alterations in fish during early stages and contribute to understanding the possible effects of global warming in early development of fish and its ecological implications.

The Direct Effects of Climate Change on Tench (Tinca tinca) Sperm Quality under a Real Heatwave Event Scenario

“…Although all organisms are able to adapt their metabolism to spatial and temporal changes in environmental temperature, such variations may have wide and deep consequences in different aspects of ectotherm biology [ 37 ], including behavior [ 38 ], feeding and digestive processes [ 39 ], skeletal muscle metabolism and mechanics [ 40 ], immunology [ 41 ], growth [ 42 ], and development [ 43 , 44 ], among others. Fish reproduction is not an exception.…”

Embryonic and Larval Development of Stinging Catfish, Heteropneustes fossilis, in Relation to Climatic and Water Quality Parameters

“…High temperatures accelerate the rate of development, resulting in the appearance of certain structures at smaller larval sizes [ 70 ], as has been observed for fin formation and metamorphosis [ 71 , 72 ]. High temperature during embryogenesis induced early hatching, mouth opening, and advanced skeletal ossification at 16 days after hatching in Atractosteus tropicus [ 73 ]. Long-lasting effects of early temperature exposure have been identified in metamorphosing gilthead seabreams, including effects such as decreased critical swimming speed and the incidence of caudal fin abnormalities [ 74 ].…”