scholarly journals Late Holocene Paleonvironmental Evolution of Two Coastal Lakes in Mediterranean Chile and Its Implications for Conservation Planning

2021 ◽  
Vol 11 (8) ◽  
pp. 3478
Author(s):  
Isis-Yelena Montes ◽  
Andy Banegas-Medina ◽  
Nathalie Fagel ◽  
Meriam El Ouahabi ◽  
Elie Verleyen ◽  
...  
Keyword(s):  
Primary Production ◽  
Late Holocene ◽  
Anthropogenic Impacts ◽  
Marked Change ◽  
Management Program ◽  
Cyanobacterial Blooms ◽  
Nutrient Inputs ◽  
Coastal Lakes ◽  
San Pedro ◽  
Exotic Tree

Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in cyanobacterial blooms in the lacustrine system of San Pedro de la Paz in the last decades. Here, we reconstructed primary production and sedimentological changes spanning the past 2500 years in two coastal lakes in Mediterranean Chile. A multiproxy approach including sedimentological, biogenic silica, carbon and nitrogen isotopes and fossil pigments analysis in sediment cores was performed in Laguna Grande (LGSP) and Laguna Chica de San Pedro (LCSP). A marked change in the sedimentology of the lakes, likely related to the terrigenous sediment inputs derived by a transition from an arid condition in the mid-Holocene to a more humid condition in the late Holocene that favoured arboreal forest establishment at 100 BC–AD 150. A period of low primary production was identified between 850 to 1050 AC for LCSP, suggesting moist and cold conditions that were possibly related to La Niña events. In recent decades, there have been increases in primary production, probably resulting from anthropogenic disturbances. These likely include the clearance of native vegetation, the introduction of exotic tree species, and urbanisation, which in turn, resulted in nutrient inputs and hence eutrophication. We conclude that an integrated management program for both lakes is urgently needed.

scholarly journals Anthropogenic impacts on Late Holocene land-cover change and floristic biodiversity loss in tropical southeastern Asia

2021 ◽  
Vol 118 (40) ◽  
pp. e2022210118 ◽  
Author(s):  
Zhuo Zheng ◽  
Ting Ma ◽  
Patrick Roberts ◽  
Zhen Li ◽  
Yuanfu Yue ◽  
...  
Keyword(s):  
Late Holocene ◽  
Southern China ◽  
Anthropogenic Impacts ◽  
Biodiversity Loss ◽  
Freshwater Wetland ◽  
Social Changes ◽  
Rice Agriculture ◽  
Human Land Use ◽  
Key Species ◽  
The Face

Southern China and Southeast Asia witnessed some of their most significant economic and social changes relevant to human land use during the Late Holocene, including the intensification and spread of rice agriculture. Despite rice growth being associated with a number of earth systems impacts, how these changes transformed tropical vegetation in this region of immense endemic biodiversity remains poorly understood. Here, we compile a pollen dataset incorporating ∼150,000 identifications and 233 pollen taxa to examine past changes in floral biodiversity, together with a compilation of records of forest decline across the region using 14 pollen records spanning lowland to mountain sites. Our results demonstrate that the rise of intensive rice agriculture from approximately 2,000 y ago led not only to extensive deforestation but also to remarkable changes of vegetation composition and a reduction in arboreal diversity. Focusing specifically on the Tertiary relic tree species, the freshwater wetland conifer Glyptostrobus (Glyptostrobus pensilis), we demonstrate how key species that had survived changing environmental conditions across millions of years shrank in the face of paddy rice farming and human disturbance.

Anthropogenic impacts to coral reefs in Palau, western Micronesia during the Late Holocene

Coral Reefs ◽  
2007 ◽  
Vol 26 (4) ◽  
pp. 915-930 ◽  
Author(s):  
S. M. Fitzpatrick ◽  
T. J. Donaldson
Keyword(s):  
Coral Reefs ◽  
Late Holocene ◽  
Anthropogenic Impacts

scholarly journals Environmental History of an Early Spanish Settlement in the Visayas, Philippines: Excavations in the Parian District of Cebu City | Kasaysayang Pangkalikupan sa usa ka Karaang Puluy-anan Katsila sa Kabisay-an, Pilipinas: Mga Nakubkoban sa Distritong Parian, Lungsod sa Sugbu

SPAFA Journal ◽  
2020 ◽  
Vol 4 ◽  
Author(s):  
John Peterson ◽  
Archie Tiauzon ◽  
Mark Horrocks ◽  
Maria Kottermair
Keyword(s):  
Environmental History ◽  
Coastal Plain ◽  
Late Holocene ◽  
Urban Landscape ◽  
Soil Profiles ◽  
San Pedro ◽  
Guadalupe River ◽  
History Of ◽  
Core Areas ◽  
The City

The Jesuit House was built in 1730 on land reclaimed from the Tinago Marsh at the edge of the early Spanish settlement of Cebu City, Philippines, two centuries after it was first encountered by the Spanish explorer Magellan. As the city expanded from its core areas ca. 1565 around Fort San Pedro, Plaza Independencia, and the sites of Santo Nino Church and the Cebu Cathedral, waterways were drained and filled, and canals were dredged to extend the urban Spanish grid. Archaeological excavations at the Jesuit House and in the nearby Casa Gorordo Annex project document these changes in the urban landscape. Soil profiles throughout the downtown coastal plain in conjunction with chronostratigraphic data from the excavations demonstrate its submergence during the late Holocene high sea still-stand, followed by dissection by local drainages and the Guadalupe River. Relict channels and distinct interfluvial terraces are observed showing a migrating series of channels along the shoreline as well as a distinct escarpment at the back of the plain that marked the limits of marine intrusion during the high still-stand. Visayans and Spanish settlers selected higher ground for settlement in the interfluves and modified lowland areas such as the marshlands one of which became the Parian District of urban Cebu. Archaeological investigations at the Jesuit House and the Casa Gorordo Annex document the environmental history as well as the transition from native to colonial lifeways at the edge of Empire.Ang Balay Hesuita natukod niadtong tuig 1730 pinaagi sa pagtambak og yuta sa Katunggan sa Tinago diha sa ngilit sa nag-unang nahimutangan sa mga Katsila sa Sugbu, Pilipinas, mga duha ka gatusan ka tuig human kini nakaplagan sa Katsilang manunuhid nga si Magallanes. Sa dihang nilapad ang lungsod, gibana-bana 1565, nga naglangkob sa Kotang San Pedro, Hawan Independencia, ug mga luna sa Simbahang Santo Nino ug Katedral sa Sugbu, ang mga katunggan gipahubas ug gitambaka’g yuta, ug ang mga kanal gihawas-asan aron sa pagpalugway sa gilapdon sa lungsuranong Katsila. Makita kining mga kausaban sa lungsod pinaagi sa mga nakubkuban sa mga arkeyologo sa Balay Hesuita ug sa Sumpay sa Balay Gorordo nga duol niini. Ang mga takilirang hulagway’ng yuta sa tibuok kabaybayunang patag sa maong lungsod, tali sa datos nga kronostratigrapiko nga nakuha pinaagi sa mga arkeyolohikong pangubkob nagapakita sa pagkalubog niini kaniadto sa kinatas-ang naabtan sa dagat sa panahon sa Holosino, gisundan kini sa pagtabas-tabas pinaagi sa mga gagmay’ng sapa ug sa Subang Guadalupe. Makita sa mga karaang giagian sa katubigan ug tataw’ng mga hinagdanan ang nagsunod-sunod nga mga agianan sa tubig subay sa baybayon ug ang mga tataw nga tagaytay sa likod sa patag nga maoy nagpaila kung asa taman niabot ang kadagatan sa panahon sa kintas-ang gihunungan niini kaniadto. Gipili sa mga lumolupyo nga Bisaya ug Katsila ang hataas nga mga lugar para ila kining puy-an taliwala sa mga dagayday ug ilang giusab ang mga basa nga mga lugar sa ubos niini, sama sa mga katunggan diin usa niini ang Ditritong Parian sa Sugbu. Ang mga pagtulun-ang arkeyologo sa Balay Hesuita ug sa Sumpay sa Balay Gorordo nagapakita sa kaagi sa kalikupan lakip na ang pag-usab gikan sa lumadnon ngadto sa kolonyal nga mga pamaagi sa kinabuhi diha sa ngilit sa Imperyo.

scholarly journals N and P as ultimate and proximate limiting nutrients in the northern Gulf of Mexico: Implications for hypoxia reduction strategies

2017 ◽  
Author(s):  
Katja Fennel ◽  
Arnaud Laurent
Keyword(s):  
Gulf Of Mexico ◽  
Primary Production ◽  
Statistical Regression ◽  
Nutrient Inputs ◽  
Nutrient Reduction ◽  
Total N ◽  
Northern Gulf Of Mexico ◽  
P Limitation ◽  
Hypoxic Area ◽  
Reduction Strategies

Abstract. The occurrence of hypoxia in coastal oceans is a growing problem worldwide and clearly linked to anthropogenic nutrient inputs. While the need for reducing anthropogenic nutrient loads is generally accepted, it is costly and thus requires scientifically sound nutrient-reduction strategies. Issues under debate include the relative importance of nitrogen (N) and phosphorus (P), and the magnitude of reduction requirements. The largest anthropogenically induced hypoxic area in North American coastal waters (of 15,000 ± 5,000 km2) forms every summer in the northern Gulf of Mexico where the Mississippi and Atchafalaya Rivers deliver large amounts of freshwater and nutrients to the shelf. A 2001 plan for reducing this hypoxic area by nutrient management in the watershed called for a reduction of N loads. Evidence of P limitation during the time of hypoxia formation has arisen since then, and has opened up the discussion about single versus dual nutrient reduction strategies for this system. Here we report the first systematic analysis of the effects of single and dual nutrient load reductions from a spatially explicit physical-biogeochemical model for the northern Gulf of Mexico. The model has been shown previously to skillfully represent the processes important for hypoxic formation. Our analysis of an ensemble of simulations with stepwise reductions in N, P and N&P loads provides insight into the effects of both nutrients on primary production and hypoxia, and allows us to estimate what nutrient reductions would be required for single and dual nutrient reduction strategies to reach the hypoxia target. Our results show that, despite temporary P limitation, N is the ultimate limiting nutrient for primary production in this system. Nevertheless, a reduction in P load would reduce hypoxia because primary production in the region where density stratification is conducive to hypoxia development, but reduction in N load have a bigger effect. Our simulations show that, at present loads, the system is saturated with N, in the sense that the sensitivity of primary production and hypoxia to N load is much lower than it would be at lower N loads. We estimate that reduction of 63 % ± 18 % in total N load or 48 % ± 21 % in total N&P load are necessary to reach a hypoxic area of 5,000 km2, which is consistent with previous estimates from statistical regression models and highly simplified mechanistic models.

scholarly journals EFECTOS DE LA RECOMUNICACIÓN DEL RÍO MAGDALENA CON SU ANTIGUO DELTA: CAMBIOS EN LA PRODUCCIÓN PRIMARIA FITOPLANCTÓNICA Y RESPIRACIÓN EN EL COMPLEJO PAJARALES, 1989 A 2005

2016 ◽  
Vol 38 (2) ◽  
Author(s):  
Johan D. Rodríguez Chila ◽  
José E. Mancera Pineda ◽  
Héctor J. López Salgado
Keyword(s):  
Organic Matter ◽  
Experimental Design ◽  
Primary Production ◽  
Net Primary Production ◽  
Nutrient Inputs ◽  
Phytoplankton Primary Production ◽  
Physical Chemical ◽  
Magdalena River ◽  
Del Rio ◽  
Associated Variables

The phytoplankton primary production, pelagic respiration, photosynthetic pigments, and physical-chemical associated variables in the Pajarales Complex, were estimated to assess the potential effects of the Magdalena River recommunication with its former delta, The study carried out between September and December 2005, followed the same experimental design than one done before to the recommunication The results show a signicant increase of the net primary production when compared with the years 1988-89 (from 598 gC/m2/year to 982 gC/m2/year). The actual production seems to be driven mainly by ammonia, and there is no correlation neither with the water transparency nor the chlorophyll a concentration. The ecosystem is less efcient in the synthesis of organic matter after the recommunication with the Magdalena river. The respiration rate increased, showing higher and more prolonged heterotrophy, which may be associated to higher organic matter and inorganic nutrient inputs from the Magdalena River. The results conrm eutrophication increase in the CP between 1989 and 2005.

LATE HOLOCENE ANTHROPOGENIC IMPACTS ON TROPICAL ECOSYSTEMS OF NORTHERN VIETNAM

2016 ◽  
Author(s):  
Christy E. Briles ◽  
◽  
Olga Serenchenko ◽  
Lora Stevens ◽  
Adam White ◽  
...  
Keyword(s):  
Late Holocene ◽  
Anthropogenic Impacts ◽  
Tropical Ecosystems ◽  
Northern Vietnam

scholarly journals Modeling the impacts of climate extremes and multiple water uses to support water management in the Icó-Mandantes Bay, Northeast Brazil

2018 ◽  
Vol 10 (4) ◽  
pp. 893-906 ◽  
Author(s):  
Elena Matta ◽  
Hagen Koch ◽  
Florian Selge ◽  
Max Nino Simshäuser ◽  
Karina Rossiter ◽  
...  
Keyword(s):  
Water Supply ◽  
Anthropogenic Impacts ◽  
Climate Extremes ◽  
Quality Parameters ◽  
Water Diversion ◽  
Water Model ◽  
Tracer Transport ◽  
Nutrient Inputs ◽  
Diversion Channel ◽  
Set Up

Abstract The hydropower production, water supply and aquaculture services of the Itaparica Reservoir are of immense importance for the Brazilian Northeast. Uncontrolled water resources consumption (e.g. irrigation, water supply), climate and land use change effects deteriorated the water quantity and quality in the reservoir, leading to socio-economic and environmental problems. In this work, a depth-averaged shallow water model was set up for the Icó-Mandantes Bay, one major branch of the reservoir, using the open TELEMAC-MASCARET system. The aim was to assess the impacts of the newly built water diversion channel, as well as the effects of a flood and tracer transport from an intermittent tributary, both located in the bay. An alternative approach to estimate the water retention times was additionally implemented. The simulations showed that though the diversion channel did not significantly influence the hydrodynamics of the bay, it is necessary to continuously monitor water quality parameters in the withdrawal, especially during rainy periods after droughts, because of the nutrient inputs from the tributary and the overflows of the nearby drainage systems. Management measures adapting to the continuously changing natural conditions and anthropogenic impacts are thus indispensable and the model presented can be a valuable supporting tool for this purpose.

Early human impacts on vegetation on the northeastern Qinghai-Tibetan Plateau during the middle to late Holocene

2017 ◽  
Vol 41 (3) ◽  
pp. 286-301 ◽  
Author(s):  
Xiao-zhong Huang ◽  
Si-si Liu ◽  
Guang-hui Dong ◽  
Ming-rui Qiang ◽  
Zhi-juan Bai ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Human Activity ◽  
Tang Dynasty ◽  
Late Holocene ◽  
Human Impacts ◽  
Anthropogenic Impacts ◽  
Lake Basin ◽  
Pollen Record ◽  
Grassland Degradation ◽  
Gonghe Basin

The ecosystems of the Qinghai-Tibetan Plateau are regarded as being primarily regulated by climate because of the harsh environment of the region and the resulting sparse human population. Recent studies have revealed that Neolithic farmers and nomads extensively settled in the northeastern Qinghai-Tibetan Plateau from 5.2 ka (ka = cal ka BP); however, it is unclear how and to what extent human activity has affected its vegetation. Here we combine the results of the pollen analysis of a sediment core from Genggahai Lake, a shallow lake in Gonghe Basin on the northeastern Qinghai-Tibetan Plateau, with archaeological evidence and use them to assess the extent and nature of human impacts on the regional vegetation during the middle and late Holocene. The pollen record indicates that Stellera, an indicator of the extent of grazing-induced grassland degradation, first appeared at 4.7 ka, expanded during 3.6–3.0 ka, and finally increased significantly after 1.6 ka. In support of this finding, archaeological data indicate that the agro-pastoral Majiayao people arrived at ∼5 ka and groups of Kayue people, who practiced pastoralism, intensively colonized the Gonghe Basin and nearby Qinghai Lake basin during 3.6–3.0 ka. After ∼1.6 ka, from the Tang Dynasty onwards, human settlement and grazing activity intensified on the northeastern Qinghai-Tibetan Plateau, and this is in accord with the observed high percentages of Stellera in the pollen record. Based on comparison with other records, we conclude that the sediments of Genggahai Lake provide a record of anthropogenic impacts on vegetation, and that human activity may have contributed to regional forest decline during the middle Holocene, and to grassland degradation in the late Holocene. Grassland degradation caused by human activity may be an indicator of the start of the Anthropocene and potentially may have contributed to global climate change via increased dust emission to the atmosphere.

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