Assessment of nitrogen flows into the Cuban landscape

Abstract

The alteration of the nitrogen (N) cycle by human activities is widespread and has often resulted in increased flows of nitrogen to the marine environment. In this paper we have attempted to know the changes of N fluxes in Cuba by quantifying the N inputs to the landscape from (1) fertilizer applications, (2) atmospheric deposition, (3) biological nitrogen fixation and (4) net import of food and feeds. N-inputs to the country progressively increased until the end of the 20th century, reaching a peak during the 80s when low cost fertilizer imported from the former Soviet Union led to heavy rates of application. This rapid growth represented more than a 5-fold increase with respect to pristine values; higher than the two-fold global increase of anthropogenic N reported by Vitousek et al. (1997 Human alteration of the global nitrogen cycle: sources and consequences. Ecol. Appl. 7:737-750). Inorganic fertilizer was the largest single source of reactive N, followed by atmospheric deposition, biological fixation, and net imports of foods and feedstocks. Nitrogen inputs peaked in 1987 and data expressed on an area basis show that N flux to the Cuban landscape, in the 80s, was one of the highest reported in the literature. During the 90s, there was a dramatic drop in nitrogen inputs mainly associated to a decrease in the use of inorganic fertilizer. Other factors reducing nutrient inflows to Cuba, during the same period, were imports of foodstuff and livestock feeds, a decrease of nitrogen oxide emissions, and a decrease in the sugar cane crop area. Using an empirical relationship (Howarth et al. 1996 Regional nitrogen budgets and riverine N & O fluxes for the drainages to the North Atlantic Ocean: Natural and human influences. Biogeochemistry 35:75-139) we present a very preliminary estimate of N-inputs to coastal waters and discuss the consequences of these changes on the coastal zone.

Integrating Anthropogenic and Climatic Factors in the Assessment of the Caribbean Spiny Lobster (<i>Panulirus argus</i>) in Cuba: Implications for Fishery Management

“…The consequence of both factors, the anthropogenic effect on nutrient and water supplies to the coastal area is reflected in the AEI time series, with high levels in 1965~1991 and low values since 1993, coincident with the periods of higher and lower recruitment and catches. Inorganic fertilizer was the largest single source of reactive nitrogen to the Cuban marine environment (Baisre, 2006). In a similar way, river damming and fertilizer consumption in agriculture activity played a significant role in the Mediterranean fishery.…”

“…Since Cuba is located in the oligotrophic Caribbean Sea (Richards and Bohnsack 1990), without significant coastal upwelling and tidal mixing, the river discharges are the main source of nutrients supporting the productivity of marine coastal fisheries (Baisre and Arboleya, 2006 (Baisre, 2006). The consequence of both factors, the anthropogenic effect on nutrient and water supplies to the coastal area is reflected in the AEI time series, with high levels in 1965~1991 and low values since 1993, coincident with the periods of higher and lower recruitment and catches.…”

“…On the other hand, Oczkowski et al (2009) found that the fishery production can be stimulated by fertilizer and sewage runoff that increases nutrient loading in an oligotrophic sea. Inorganic fertilizer consumption by agricultural activities is the largest single source of nitrogen and probably of other nutrients to Cuban landscape (Baisre, 2006).…”

“…Therefore the aim of this article is to evaluate anthropogenic and climate factors that could impact the Cuban spiny lobster stock, through their possible direct or indirect effects on the recruitment success. Some previous results examined the anthropogenic effect on the supply of water and nutrients from the terrestrial system to the Cuban marine coastal area (Baisre, 2006;Baisre and Arboleya, 2006) and the increase of the potential destructiveness of tropical cyclones in the North Atlantic (Emanuel, 2005). Therefore, we integrated two indices related to water and nutrients supply and tropical cyclones activity in the assessment of Cuban spiny lobster dynamics.…”

Atmospheric Deposition of Nitrogen to a Caribbean Coastal Zone (Cayo Coco, Cuba): Temporal Trends and Relative Importance as a Nitrogen Source

“…In Cuba, due to the absence of important coastal upwelling, and to the low tidal ranges, the main sources of nutrients to the coastal zone are limited to atmospheric deposition, N 2 fixation and river, groundwater, and wastewater discharges (Baisre 2006). Nevertheless, the economic crisis that started in Cuba since the collapse of the socialist countries in 1989 has caused drastic reductions of N inputs in the country, including the use of fertilizers, industrial activity, and fossil fuel consumption.…”