Mangrove ecosystems and shrimp farming interactions along tropical coastlines; a physical and chemical assessment

Shrimp farming is one of most serious threats to the integrity of mangrove ecosystems. Expansion of shrimp ponds have reduced mangrove area as well as affected their natural biogeochemical behaviour. At the global scale, carbon stock from the mangrove biomass and soil has been directly lost due to conversion to shrimp ponds. At the local scale, effluent water, rich in particulate and dissolved organic and inorganic nutrients as well as antibiotics and heavy metals, have modified the natural processes of assimilation, decomposition, mineralization, sequestration of natural elements.

In this presentation we provide a brief assessment of the biogeochemical interactions between shrimp farms, their associated effluents, and mangroves. One main issue is the impact on the carbon cycle. In addition to the diminution of mangrove carbon stock, microbial processes, organic carbon concentration and degradation mechanisms differ from a pristine to a shrimp effluent mangrove. Similarly to the carbon element, ecosystem health is also affected by adjacent shrimp farms. As an example, previous studies estimated that only about 30 and 15%, respectively, of total nitrogen (N) and phosphorus (P) discharged in pounds are assimilated by shrimps. Therefore, most of these fertilizers are rapidly drained towards the adjacent mangroves, leading to eutrophication risks, by enhancing primary and bacterial activity. Higher heavy metals and antibiotic concentrations have also been observed in adjacent mangroves (with seasonal and spatial variations). This presentation aims at answering the question: How is shrimp farming affecting the natural behaviour of mangrove ecosystems?

Describing the impact of shrimp aquaculture on mangroves is highly relevant to suggest sustainable practice along coastal areas. Mangroves provide a large range of ecosystem services which protect and support coastal communities and activities, such as shrimp production itself. We argue that mangroves, and their associated natural processes, should be considered/integrated into the coastal shrimp production system. This presentation addresses the major risks of the shrimp aquaculture on mangrove ecosystem and suggests some natural benefits that mangroves can provide for developing a more sustainable shrimp production, such as biofiltration or natural fertilizers.