The imperiled fish fauna in the Nicaragua Canal zone

Abstract

Large‐scale infrastructure projects commonly have large effects on the environment. The planned construction of the Nicaragua Canal will irreversibly alter the aquatic environment of Nicaragua in many ways. Two distinct drainage basins (San Juan and Punta Gorda) will be connected and numerous ecosystems will be altered. Considering the project's far‐reaching environmental effects, too few studies on biodiversity have been performed to date. This limits provision of robust environmental impact assessments. We explored the geographic distribution of taxonomic and genetic diversity of freshwater fish species (Poecilia spp., Amatitlania siquia, Hypsophrys nematopus, Brycon guatemalensis, and Roeboides bouchellei) across the Nicaragua Canal zone. We collected population samples in affected areas (San Juan, Punta Gorda, and Escondido drainage basins), investigated species composition of 2 drainage basins and performed genetic analyses (genetic diversity, analysis of molecular variance) based on mitochondrial cytb. Freshwater fish faunas differed substantially between drainage basins (Jaccard similarity = 0.33). Most populations from distinct drainage basins were genetically differentiated. Removing the geographic barrier between these basins will promote biotic homogenization and the loss of unique genetic diversity. We found species in areas where they were not known to exist, including an undescribed, highly distinct clade of live bearing fish (Poecilia). Our results indicate that the Nicaragua Canal likely will have strong impacts on Nicaragua's freshwater biodiversity. However, knowledge about the extent of these impacts is lacking, which highlights the need for more thorough investigations before the environment is altered irreversibly.

Pervasive admixture and the spread of a large‐lipped form in a cichlid fish radiation

“…Interspecific competition is widely considered an important driver of adaptation to underexploited ecological opportunities (Schluter, 2000;Yoder et al, 2010). Relative to other large lakes where cichlids have radiated rapidly, the diversity of fish species in the two Nicaraguan great lakes is comparably lower (Bussing, 1976), although we lack the complete picture on the distribution and abundance of many species in this region (Härer et al, 2017). In combination with relatively low levels of interspecific competition, high admixture and introgression between the species could homogenize much of the genome, overcoming reproductive isolation as a result of divergent selection, relaxing selection on niche specialization and, ultimately, diversification (Barluenga et al, 2006).…”

Neotropical freshwater fishes imperilled by unsustainable policies

“…During the last half century, human threats transformed unique, pristine or highly diverse regions—the Maya Mountains, Caribbean drainages, Lake Nicaragua, Andean headwaters, Cerrado savannas, Caatinga semi‐arid ecosystems, Atlantic rainforest remnants, Pantanal wetlands, Gran Chaco, Llanos del Orinoco and Moxos, and Chilean Patagonia (e.g. Abilhoa, Braga, Bornatowski, & Vitule, ; Alcorn, Zarzycki, & de la Cruz, ; Cooney & Kwak, ; Esselman et al., ; Habit & Cussac, ; Harer, Torres‐Dowdall, & Meyer, ; Killeen, ; Klink & Machado, ; Leal, Silva, Tabarelli, & Lacher, ). Even the Amazon system, relatively well preserved, is under pressure by urban, hydropower, mining and agribusiness expansion (Castello et al., ; Lees, Peres, Fearnside, Schneider, & Zuanon, ; Winemiller et al., )—and currently by non‐native species (Bittencourt, Silva, Silva, & Tavares‐Dias, ; Padial et al., ; Van Damme et al., ).…”

“…Our specific analysis focused on Brazil, but unsustainable activities such as hydropower expansion, land use changes and the introduction of non‐native organisms are widespread across the Neotropical region. The situation is more dramatic if we consider that many other activities (not considered here) are planned or in course to accelerate regional development, for example roads, railways, ports, waterways and power plants (Harer et al., ; Huete‐Perez, Tundisi, & Alvarez, ; Killeen, ; Lapola et al., ; Lima Junior et al., ). Furthermore, prohibited harmful actions are growing across the region, such as clandestine fish introductions, overfishing, pollution, fires, illegal mining and deforestation (e.g.…”

“…Countries in Latin America have proposed strategic actions to accelerate economic growth (e.g. Alcorn et al., ; Anderson et al., ; Bellfield, ; Bernard et al., ; Castello & Macedo, ; Cremers et al., ; Finer & Jenkins, ; Harer et al., ; Killeen, ; Lapola et al., ; Lees et al., ; Valladão et al., ), and some countries (e.g. Brazil) became leading economies among emerging nations.…”

Frank Golley’s Perspectives on Environmental Ethics and Literacy: How to Avoid Irreversible Impacts of Hydro-Power and Inter-Oceanic Canal Development on Mesoamerican Tropical Ecosystems

“…Mixing of native and non-native invasive species could greatly alter the biodiversity and food web of the lake. Impacts of the proposed excavations on freshwater fish continue to be identified, but much more study is needed (Härer et al, 2017). Large environmental impacts on the Brito River Estuary and unique western tropical dry forest ecosystems are also highly likely (Muñoz Ardila et al, 2017).…”