The evolutive and adaptive capacity of Antarctic fish

Antarctica is a continent located in the South Pole and has been surrounded by a circumpolar current for over 40 million years. This barrier keeps warmer waters and non native species away from the continent, but fish that inhabit Antarctic waters are well adapted to temperatures between -2 to 2℃.

In the Antarctic ocean, the marine fauna includes 222 fish species, of which 101 belong to the suborder Notothenioidei. This suborder includes 8 families and is the most abundant in the Ross Sea.

These species developed unique structural, physiological and behavioral characteristics. Some of these evolutive characteristics resulted from regressive events such as:

– antifreeze proteins that protect the organism from freezing in temperatures below zero;

– low bone density, i.e., less calcium concentrations, with consequent decrease in energy needed for movement;

– low metabolism, which also contributes to low energy losses;

– loss of blood hemoglobin, which makes the blood almost translucid, and consequent decrease in oxygen transport;

– aglomerular kidneys, i.e. lack of glomerular Malpighi needed for blood filtration in most species;

– higher mitochondrial density.

These characteristics, and others, were developed for thousands of years and resulted in the adaptation and survival of these fish species to the harsh conditions of the Antarctic ocean. However, climate change can affect the region through the disruption of the Antarctic circumpolar current and, consequently allow invasive species to move south. Currently, a group of researchers from the Centro de Ciências do Mar (CCMAR), including myself, are focusing on the evolution of the immune system in Antarctic fish and potential response, as well as defense mechanisms, to temperature increase and interaction with new, potentially pathogenic species (e.g. bacteria, viruses, fungus) that can threat their survival.

——–

Source: Matschiner, M., Colombo, M., Damerau, M., Ceballos, S., Hanel, R., Salzburger, W. (2015). The adaptive radiation of Notothenioid Fishes in the Waters. Extremophile Fishes, 35-57. doi: 10.1007/978-3-319-13362-1_3

Author: Cármen Sousa

Share

Leave a Reply