Poster Presentation International Conference on River Connectivity (Fish Passage 2018)

Barriers to migration: impacts of barotrauma on fish physiology (#216)

Helen A.L. Currie , Nicholas Flores Martin 1 , Gerardo Espindola Garcia 1 , Isabella Cristina Resende Ramos 2 , Paul S. Kemp 1 , Luiz G.M. Silva 2 3
  1. University of Southampton, Southampton, HAMPSHIRE, United Kingdom
  2. Departamento de Technologia e Engenharia Civil, Universidade Federal de São João del-Rei, Ouro Branco, Minas Gerais, Brasil
  3. Institute for Land, Water & Society, Charles Sturt University, Albury-Wondonga, New South Wales, Australia

Brazil is home to some of the largest dams in the world, relying on renewable energy sources for electricity generation, and with aims to further expand.  It also boasts the greatest continental species richness on the globe, housing approximately 2300 freshwater fish species including a number of commercially viable migratory species.  Migratory Prochilodus lineatus (“Curimbatá” or “Curimba” in Portuguese; “Sábalo” in Spanish) are considered to be a keystone species due to their importance within the food chain, and internal consumption and exportation value.  Accounting for 50 – 90 % of the biomass in its primarily native Paraná river basin, populations are on the decline, with breeding programmes in place in an attempt to restock waterways. 

Large scale hydropower dams act as inaccessible barriers to migration, causing blockades, physiological damage, and mortality across life-stages including sexually mature adults, juveniles, and drifting fertilised eggs.  Mortality rates of fish at hydropower sites are measured by the tonnage.  Instant death or injury is well understood as a result of blade strike, however less well understood are the indirect physiological effects of rapid pressure fluctuations. 

Using a custom built, manually controlled barotrauma chamber, Prochilodus lineatus were exposed to simulations of rapid decompression, similar to those occurring in a turbine, to assess the injurious effects on fish physiology.  Tested scenarios using different rates of pressures changes (RPC), only represented a fraction of what may be experienced whilst traversing hydropower structures.  Results of internal and external damage assessment (i.e. heart emboli; gill emboli; stomach emboli; expanded swimbladder; ruptured swimbladder chamber; or external haemorrhaging) however collectively indicate that even slight increases in RPC can cause irreparable damage to physotomous fish physiology.