Functional and trophic diversity of fishes in the Mekong-3S river system: comparison of morphological and isotopic patterns

Montaña, Carmen G.; Ou, Chouly; Keppeler, Friedrich W.; Winemiller, Kirk O.

doi:10.1007/s10641-020-00947-y

Cited by 17 publications

(16 citation statements)

References 43 publications

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“…In 2008, the total active storage capacity of reservoirs in the Mekong River basin was 8.6 km 3 , or 2% of its annual discharge [33,34]. The basin can activate the reservoir storage to 86.8 km 3 by 2025, approximately 20% of its annual discharge [24,34]. However, the existing and planned dams in China were not counted [35], which shows the active and dead storage of 8.7 km 3 by 2025.…”

Section: The Proposed Eleven Hydropower Dams In the Mekong River Mainmentioning

confidence: 99%

“…Such impacts are also documented for some dams in the LMB [12,21,27,41,42]. Dams create reservoirs that may support large fisheries, but the overall effect of large dams is usually a loss of fish production [16,24,43]. It has been shown that fisheries in the Mekong Delta are principally controlled by flow regime, nutrient dynamics correlated with transport and removal of sediments, and barriers to migration [38].…”

Section: Impacts On Fisheriesmentioning

confidence: 99%

“…There has been an increase in power demand in these regions, and future demand is forecasted to be even greater. Volatile prices in international energy markets have intensified interest in hydropower development [22][23][24][25]. Governments, especially Lao PDR, have harbored potential earnings from hydropower development for reducing poverty, lowering national debts, supporting economic growth as well as achieving regional energy security.…”

mentioning

confidence: 99%

“…Governments, especially Lao PDR, have harbored potential earnings from hydropower development for reducing poverty, lowering national debts, supporting economic growth as well as achieving regional energy security. On the other hand, it is argued that the proposed dams might cause significant and negative effects on fisheries and agriculture of the LMB [22][23][24][25]. The benefits from hydropower generation may provide 6-32 billion USD but the potential damage from fisheries capture may reach 2-13 billion USD [13,25].…”

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confidence: 99%

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Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin

et al. 2020

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The riverine ecosystems of the Mekong River Basin possess the world’s most productive inland fishery and provide highly productive food crops for millions of people annually. The development of hydropower potential in the Mekong River has long been of interest to governments in the region. Among the existing 64 dams, 46 dams have been built in the Lower Mekong Basin (LMB) to produce up to 8650 MW of electricity. Additionally, of the 123 proposed built hydropower dams, eleven hydropower plants have been nominated for the river mainstream and are expected to install a total of 13,000 MW in the LMB countries. However, serious concerns have intensified over the potential negative economic consequences, especially on fisheries and agriculture in Cambodia and Vietnam. To date, most of the concerns have concentrated on the impacts on hydrology, environment, livelihood, and diversity in the LMB attributed to hydropower development. This paper, however, discusses the fishery and agricultural sectors of the LMB and focuses on the downstream floodplains of Cambodia and Vietnam. The dam construction has caused greater losses of biodiversity and fisheries than climate change in the LMB. The reduction of 276,847 and 178,169 t of fish, 3.7% and 2.3% of rice, 21.0% and 10.0% of maize will contribute to a decrease of 3.7% and 0.3% of the GDP of Cambodia and Vietnam, respectively. Lao PDR may benefit the most revenue from electricity generation than the other country in the LMB, as most of the proposed dams are projected in the country. Cambodia burdens 3/4 of the reduction of total capture fishery destruction, whilst Lao PDR, Thailand, and Vietnam endure the remaining 1/3 losses. The tradeoff analyses reveal that losses of capture fisheries, sediment or nutrients, and social mitigation costs are greater than the benefits from electricity generation, improved irrigation, and flood control of the LMB region. The socioeconomic and environmental damage caused by hydropower dams in developing countries, including the Mekong, is greater than the early costs in North America and Europe. It is proposed that dam construction for hydropower in the Mekong River, as well as other rivers in developing countries, should be gradually removed and shifted toward solar, wind, and other renewable resources.

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Section: The Proposed Eleven Hydropower Dams In the Mekong River Mainmentioning

confidence: 99%

Section: Impacts On Fisheriesmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin

et al. 2020

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“…For most species, we sampled 3 individuals, although in a few cases this number was higher (max = 7) or lower (min = 2) depending on availability of preserved specimens from the field studies (Table S1). Although not uncommon in community ecology studies (e.g., Montaña, Ou, Keppeler, & Winemiller, 2020), small isotopic sample sizes may provide poor representation of species/population isotopic signatures when there is high variation associated with isotopic samples. This could ultimately weaken the association between isotopic ratios and other datasets (e.g., diet and morphological traits).…”

Section: Isotopic Datamentioning

confidence: 99%

Can ancestry and morphology be used as surrogates for species niche relationships?

Keppeler

Winemiller

2020

Ecology and Evolution

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Species interactions are difficult to quantify, and, consequently, many studies have used species traits and phylogeny as proxies under an assumption of niche conservatism (i.e., closely related and morphologically similar species should have similar niches). However, few studies have investigated whether niches actually are conserved within and across diverse communities. Here, we tested the degree to which phylogenetic relatedness and morphological similarity predict diets and stable isotopic ratios (δ15N and δ13C), two common descriptors of the trophic niche, in fish assemblages of two small streams in the Neotropics. We also tested the strength of the association between isotopic ratios and diet composition and found significant correlations implying that isotopic signals reveal trophic structure despite error associated with estimates of trophic enrichment and variation associated with tissue preservation, metabolism, and other factors affecting isotopic ratios. Morphological traits yielded a significant phylogenetic signal, and both morphological traits and phylogeny were correlated with diet composition, with morphological traits being a stronger predictor. We infer that functionally relevant morphological traits of fish can be used to infer trophic niches for certain kinds of questions and analyses when trophic data are lacking. However, we highlight that using phylogenetic and morphological data in combination with dietary and/or isotopic data can improve resolution of assemblage trophic structure and niche diversification.

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Trophic Ecology and Resource Partitioning of Common Snook and Mexican Snook in the Usumacinta River Delta

et al. 2022

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Coexisting species often develop resource‐partitioning mechanisms to reduce their direct competition and optimize energy harvesting. Common Snook Centropomus undecimalis and Mexican Snook C. poeyi are carnivorous fish that coexist in estuaries of the Usumacinta River delta, in the southern Gulf of Mexico, and play an important role for fisheries and economy in this region. We analyzed spatial, temporal, and ontogenetic variability in trophic dynamics and distribution of Common and Mexican snooks. To identify patterns of trophic resource partitioning, we analyzed stomach content and stable isotopes (δ13C, δ15N) of the two species. Fifty‐one prey items were identified, with fish remains being the most abundant component (>35%). The two snook species appeared to be specialized carnivores of the third or fourth trophic level. Diet comparison indicated significant differences among species: Common Snook presented a higher proportion of fish from the families Engraulidae, Clupeidae, and Elopidae, while Mexican Snook consumed a higher fraction of fish from the families Cichlidae, Poeciliidae, and Loricariidae. The diet also presented significant variations between size‐classes. Small‐sized (<350 mm SL) Common Snook showed significantly higher reliance on invertebrates than large‐sized fish (>500 mm SL). Medium‐sized (351–499 mm SL) Mexican Snook consumed a higher proportion of Poeciliidae fish than small‐sized or large‐sized fish. The diet of the two snook species also presented important differences among seasons and sites. Trophic niche overlap between Common and Mexican snooks varied among systems, with higher overlap in the Pom−Atasta system than in the Palizada River. This study indicates that Common Snook and Mexican Snook have developed strategies for spatial partitioning of resources that favor their coexistence in the Usumacinta River delta.

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Functional and trophic diversity of fishes in the Mekong-3S river system: comparison of morphological and isotopic patterns

Cited by 17 publications

References 43 publications

Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin

Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin

Can ancestry and morphology be used as surrogates for species niche relationships?

Trophic Ecology and Resource Partitioning of Common Snook and Mexican Snook in the Usumacinta River Delta

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