Novel responses of diatoms in neotropical mountain lakes to indigenous and post-European occupation

Vélez, María Isabel Álvarez; Salgado, Jorge; Brenner, Mark; Hooghiemstra, H.; Escobar, Jaime; Boom, Arnoud; Bird, Broxton W.; Curtis, Jason H.; Temoltzin-Loranca, Yunuén; Patiño, Luisa; González‐Arango, Catalina; Metcalfe, Sarah E.; Simpson, Gavin L.; Velásquez, César

doi:10.1016/j.ancene.2021.100294

Cited by 14 publications

(13 citation statements)

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“…The aquatic community of Namonte also displays evidence of considerable change during this time. Increases in abundance of colonizers S. pinnata, and A. minutissimum (Berthon et al, 2011) and LP and MP species, indicate intermittent physical disturbance, possibly associated with habitat degradation, highly variable lake levels, and environmental changes in the watershed (Passy, 2007;Berthon et al, 2011;Velez et al, 2021). High variation in the abundance of sedges and a relative increase in the abundance of Typha also support an inference for changes in lake level and periodic swampy conditions.…”

Section: Virahmentioning

confidence: 74%

“…Diatom species were grouped according to ecological guilds and motility into High Profile (HP), High Profile Planktonic (HPP), Low Profile (LP) and Motile Profile (MP), following Passy (2007) and Berthon et al (2011) (Supplementary Material 4). Although most of the studies on diatom functional groups and disturbance have been conducted in rivers and streams, the multi-proxy analyses presented in Velez et al (2021) showed that they can be used to identify anthropogenic disturbances, including drainage and deforestation, with the consequent changes in water level, water transparency and macrophyte cover. These guilds reflect the forms and life habits of diatoms that are adaptations to particular physical (currents, turbidity) and chemical (nutrients) conditions (Leira et al, 2015;Algarte et al, 2016).…”

Section: Sediment Sampling and Processingmentioning

confidence: 99%

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Influence of Late Holocene Climate Change and Human Land Use on Terrestrial and Aquatic Ecosystems in Southwest Madagascar

et al. 2021

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Madagascar’s biota underwent substantial change following human colonization of the island in the Late Holocene. The timing of human arrival and its role in the extinction of megafauna have received considerable attention. However, the impacts of human activities on regional ecosystems remain poorly studied. Here, we focus on reconstructing changes in the composition of terrestrial and aquatic ecosystems to evaluate the impact of human land use and climate variability. We conducted a paleoenvironmental study, using a sediment record that spans the last ∼1,145 years, collected from a lakebed in the Namonte Basin of southwest Madagascar. We examined physical (X-ray fluorescence and stratigraphy) and biotic indicators (pollen, diatoms and micro- and macro-charcoal particles) to infer terrestrial and aquatic ecosystem change. The fossil pollen data indicate that composition of grasslands and dry deciduous forest in the region remained relatively stable during an arid event associated with northward displacement of the Intertropical Convergence Zone (ITCZ) between ∼1,145 and 555 calibrated calendar years before present (cal yr BP). Charcoal particles indicate that widespread fires occurred in the region, resulting from a combination of climate drivers and human agency during the entire span covered by the paleorecord. Following settlement by pastoral communities and the disappearance of endemic megafauna ∼1,000 cal yr BP, grasslands expanded and the abundance of trees that rely on large animals for seed dispersal gradually declined. A reduction in the abundance of pollen taxa characteristic of dry forest coincided with an abrupt increase in charcoal particles between ∼230 and 35 cal yr BP, when agro-pastoral communities immigrated into the region. Deforestation and soil erosion, indicated by a relatively rapid sedimentation rate and high K/Zr and Fe/Zr, intensified between 180 and 70 cal yr BP and caused a consequent increase in lake turbidity, resulting in more rapid turnover of the aquatic diatom community. Land use and ongoing climate change have continued to transform local terrestrial and freshwater ecosystems during the last ∼70 years. The current composition of terrestrial and aquatic ecosystems reflects the legacy of extinction of native biota, invasion of exotic species, and diminished use of traditional land management practices.

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Section: Virahmentioning

confidence: 74%

Section: Sediment Sampling and Processingmentioning

confidence: 99%

Influence of Late Holocene Climate Change and Human Land Use on Terrestrial and Aquatic Ecosystems in Southwest Madagascar

et al. 2021

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“…The diatom assemblage during this period was composed almost exclusively of small Fragilaria sensu lato taxa, known to be dominant in many Arctic lake ecosystems (Lotter and Bigler, 2000). S. venter and S. pinnata are classified as tychoplanktonic (Velez et al 2021) and oligohalobian-indifferent (Campeau et al 1999b), primarily freshwater species capable of tolerating slightly brackish waters, providing further evidence of a predominantly freshwater environment with minimal influence from the Beaufort Sea. These taxa can exploit low-light conditions and long ice cover / short growing season lengths in cold climates like the Arctic (Keatley et al, 2008, Narancic et al 2021, and have been identified as pioneering taxa (e.g.…”

Section: Discussionmentioning

confidence: 85%

Climatic drivers of limnological change in Iqallukvik Lake, Tuktoyaktuk, Northwest Territories, Canada

et al. 2022

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The Tuktoyaktuk coastlands contain thousands of lakes along an area of the Beaufort Sea in the rapidly changing western Arctic. These lakes may be susceptible to a range of impacts associated with climate warming, including potential increased marine influence changes associated with reduced lake ice cover and thawing permafrost. We examined a 210Pb-dated sediment core from Iqallukvik Lake to reconstruct ecosystem change over the last several hundred years using sediment particle size analysis and diatom subfossils. Changes in sediment texture over the past ~200 years were broadly aligned with inferred changes in regional precipitation, known to be an important driver of regional lake level in the Tuktoyaktuk coastlands. Diatoms were functionally absent at the bottom of the sediment core, but increased after ~1850, likely in response to early warming, with further floristic changes due to accelerated warming over the last century. Diatoms throughout the core are predominantly freshwater species tolerant of broad salinity concentrations, indicating Iqallukvik Lake is likely subject to minimal direct marine influence and has not been impacted by notable inundation over the recent past. Overall, this research suggests that climate impacts to Iqallukvik Lake mainly the length of the ice-free season.

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“…5). Second, when the sediment that is generated by water erosion on the hillslopes is transferred downslope to the river network, sediment storage, erosion and remobilization can occur across the river system (Romans et al, 2016;Verstraeten et al, 2017). The effect of a specific intervention (like forestation) on soil erosion on the hillslopes is therefore not directly leading to a similar change in sediment yield at the outlet of the catchment (Fig.…”

Section: Gap Between Plot-scale and Catchment-scale Erosion Assessmentsmentioning

confidence: 99%

“…More than 85 million people lived in the Andean region by 2020, with the northern Andes being one of the most densely populated mountain regions in the world (Devenish and Gianella, 2012). The demographic growth and a stagnating agricultural productivity per hectare led to an expansion of the total agricultural land area, either upward to steep hillsides at high elevations covered by native grassland-wetlands ecosystems (Velez et al, 2021), or downward to lands east and west of the Andes covered by tropical and subtropical forests (Wunder, 1996). Land abandonment is widespread where smallholders faced unfavorable economic conditions due to restricted land bases, limited availability of farm credit and low productivity in fragile agro-ecological environments (Zimmerer, 1993).…”

Section: Introductionmentioning

confidence: 99%

The effect of natural infrastructure on water erosion mitigation in the Andes

Vanacker

Molina

Rosas

et al. 2022

SOIL

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Abstract. To expand the knowledge base on natural infrastructure for erosion mitigation in the Andes, it is necessary to move beyond case by case empirical studies to comprehensive assessments. This study reviews the state of evidence on the effectiveness of interventions to mitigate soil erosion by water and is based on Andean case studies published in gray and peer-reviewed literature. Based on a systematic review of 118 case studies from the Andes, this study addressed the following research questions. (1) Which erosion indicators allow us to assess the effectiveness of natural infrastructure? (2) What is the overall impact of working with natural infrastructure on on-site and off-site erosion mitigation? (3) Which locations and types of studies are needed to fill critical gaps in knowledge and research? Three major categories of natural infrastructure were considered: restoration and protection of natural vegetation, such as forest or native grasslands, forestation with native or exotic species and implementation of soil and water conservation measures for erosion mitigation. From the suite of physical, chemical and biological indicators commonly used in soil erosion research, two indicators were particularly relevant: soil organic carbon of topsoil and soil loss rates at plot scale. The protection and conservation of natural vegetation has the strongest effect on soil quality, with 3.01±0.893 times higher soil organic carbon content in the topsoil compared to control sites. Soil quality improvements are significant but lower for forestation and soil and water conservation measures. Soil and water conservation measures reduce soil erosion to 62.1 % ± 9.2 %, even though erosion mitigation is highest when natural vegetation is maintained. Further research is needed to evaluate whether the reported effectiveness holds during extreme events related to, for example, El Niño–Southern Oscillation.

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Novel responses of diatoms in neotropical mountain lakes to indigenous and post-European occupation

Cited by 14 publications

References 54 publications

Influence of Late Holocene Climate Change and Human Land Use on Terrestrial and Aquatic Ecosystems in Southwest Madagascar

Influence of Late Holocene Climate Change and Human Land Use on Terrestrial and Aquatic Ecosystems in Southwest Madagascar

Climatic drivers of limnological change in Iqallukvik Lake, Tuktoyaktuk, Northwest Territories, Canada

The effect of natural infrastructure on water erosion mitigation in the Andes

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