Small Oceanic Islands (SOIs) face distinct vulnerabilities to climate change, presenting significant challenges for sustainable aquaculture expansion. While many aquaculture initiatives focus on high-trophic finfish, their dependence on external feed inputs and sensitivity to environmental stressors often limit their suitability in oligotrophic waters. This is especially pertinent as ocean temperatures rise and acidification increases. This abstract proposes a strategic approach to species selection in mariculture for SOIs, prioritizing low-trophic species that efficiently utilize existing marine resources and demonstrate enhanced resilience to climate change impacts.
Located in the Northeastern Atlantic, the Macaronesia Archipelagos (Madeira, Canaries, and the Azores) serve as a relevant case study for Project ACUICONECTA (1/MAC/1/1.1/0123, Interreg MAC2021-2027). This relevance stems from their oligotrophic oceanic waters and, specifically for Madeira and the Canaries, an established offshore aquaculture sector primarily focused on gilthead seabream (Sparus aurata). We recommend diversifying into species such as specific macroalgae and herbivorous invertebrates (e.g., abalone, limpets and sea urchins) through integrated multi-trophic aquaculture (IMTA) systems. These low-trophic organisms can derive nutrition directly from the water column or lower levels of the food web, reducing the reliance on finite wild fisheries for feed and minimizing the carbon footprint of aquaculture. Moreover, these species often demonstrate greater physiological tolerance to varying temperatures and pH levels, making them inherently more resilient to the projected scenarios of climate change. However, increasing seawater temperatures may pose challenges for early life stages and could lead to a greater dependence on energy-intensive hatchery cooling systems.
The strategic integration of low-trophic cultures can also provide valuable ecosystem services, such as nutrient cycling and potentially offering refuge or food for wild fish populations. By co-locating or integrating these cultures with existing offshore sea bream operations, we can explore synergistic benefits, including optimized spatial use and potential enhancements to local trophic dynamics.