Global climate change and local aquaculture

E-mail Print


Editors Note: The following is from Issue 21.
By Tarsicio Antezana
Global climate change caused by the increase in greenhouse gases requires greater knowledge of ecosystems and major changes to extraction and the way natural resources are used in Chile.
The impact of climate change and the increasingly serious effects of aquaculture in inland seas call for urgent and radical behavioral and policy changes. While acidification in the ocean on a global scale has reached 26 percent and the reduction in oxygen dissolved stands at less than 2 percent, aquaculture has produced acidification of 900 percent and a 71 percent reduction in oxygen in water near to industrial salmon and mussel farms.
The reduction in oxygen causes suffocation and death, while acidification leads to malformations of the shells of many marine organisms, in this way threatening the survival of marine life. However, the Chilean government, academics, and aquaculture companies have all failed to study the extent of this problem and the impact of oxygen reduction and a decrease in the pH level on biodiversity and the structure and functioning of benthic and pelagic communities (plankton and nekton).
There has been a systematic failure to evaluate, mitigate and eliminate many of the other impacts of aquaculture, such as pollution on the coast and the sea bottom, the dumping of pesticides, antibiotics, the introduction of disease, and the escape of salmon.
Other effects are less well known, but that does not mean that their consequences are any less severe. Chilean mussel farming turns the sea into a desert bereft of food for pelagic fauna due to its high phytoplankton filtration capacity, which in turn rains down large quantities of feces or pseudofeces on the sea bottom which eventually disperse toward the coastline.
This can have serious consequences when the salmon farms are located near wetlands (such as Pullao, Putemun, Curaco Chullec and Quinchao, in the Chiloe archipelago). These areas are a high priority for conservation because they are home to between 70 and 90 percent of the Hudsonian godwit (Limosa haemastica) population. These shorebirds migrate to the Southern Hemisphere from Alaska and Canada to avoid the winter there. Chilean mussel farming in the area is associated with the recent formation of putrefied black silt and a lack of food for the species when it returns to reproduce. This is a further example of the impact of aquaculture (these areas were deemed “suitable for aquaculture”) as a result of the apathy, ignorance and operational inefficiency of those responsible for the protection of the country’s natural heritage.
The Chilean government’s approach to “development” focuses on economic growth driven by private sector activity at the expense of the preservation of rural and coastal culture. Laws concerning the environment and aquaculture have been shaped by private interests, which means that the authorities have not considered the marine ecosystem as a harmonious whole and have ignored the interaction of chemistry, physics, biology, meteorology and geology in the ocean, as well as the numerous problems with aquaculture (such as the impact of red tides, the capacity to absorb pollution, carrying capacity, the spread of disease, the use of pesticides and the protection of biodiversity).
In addition to reexamining the principle of subsidiarity in the use of this marine heritage, which has had a major environmental and social impact, and has completely neglected its structure and the functioning of its ecosystems, we should declare an urgent moratorium on aquaculture until a rigorous evaluation can be carried out on four elements: carrying capacity, pollution, the capacity of bacteria to absorb the overload of pollutants, and the impact of antibiotics and pesticides.
This moratorium should apply to the expansion of aquaculture to pristine environments, national parks and areas that are used by the indigenous peoples of the Magallanes region. Simultaneously, I urge the creation of an Institute for Marine Sciences and Culture in the province of Chiloé and Guaitecas, and a significant increase in investment in marine science research in Chile. Are self-reflection and major changes to national environment policy concerning ecosystems and aquaculture in inland seas too much to hope for? Or will we have to wait for widespread civilian protest in the country?
The author, Tarsicio Antezana, is an oceanographer. He divides his time between Chiloe, where he leads the local citizen group Association for Defense of Environment and Culture, and California where he is a visiting researcher at Scripps Institution at UC San Diego and the Interamerican Tropical Tuna Commission.