First insights into the influence of temperature on reproduction in Antarctic fish: The case of Notothenia coriiceps

Abstract

Understanding the reproductive biology of Antarctic notothenioid fish species is crucial for effective management and conservation efforts. This study investigates the reproductive biology of Notothenia coriiceps, focusing on the location of spawning grounds and the influence of environmental factors on this process. Sampling included 120 specimens caught at Potter Cove, South Shetland Islands, from November to late March of years 2016–2018 (austral spring-summer season). Gonadal macroscopic, histologic and physiologic features are reported. Histological analysis revealed two distinct groups of oocytes in the ovaries: a leading clutch of vitellogenic oocytes for the upcoming reproductive event and a second remnant clutch of smaller oocytes in cortical alveoli and primary growth stages. Photoperiod phases significantly associate with variations in the gonadosomatic index throughout ovarian development, indicating the influence of this parameter on fish reproduction at high latitudes. Elevated plasma levels of estradiol during vitellogenesis support its role in stimulating yolk precursor synthesis and incorporation into oocytes. In March, an increase in testosterone levels during late vitellogenesis suggests the proximity of final maturation, ovulation, and spawning. A sharp increase in both sex steroids and accelerated gonadal development of N. coriiceps was particularly evident after water temperature reached maximum values (∼2 °C), suggesting that high temperature acts as a driver of the physiological mechanisms that allow to complete vitellogenesis and reach the ovulation. Our results show that (1) N. coriiceps females captured in mid-March at Potter Cove were in late developing, suggesting that spawning likely start on April; (2) Potter Cove is likely a spawning ground for N. coriiceps in part due to its thermal regime, emphasizing the importance of inshore areas as spawning grounds for Antarctic notothenioids. Thus, this study underscores the necessity of investigating the impact of water temperature changes on notothenioids reproductive patterns in the context of global warming at West Antarctic Peninsula region.