Mapping the solution space for local adaptation under global change: A test of concept for the Vietnamese Mekong delta

Over the course of the last century, humans have witnessed drastic levels of global environmental change that endangered both, the survival of single species as well as biodiversity itself. This includes climate change, in both environmental means and in variance and subsequently frequent extreme weather events, as well as land use change that species have to cope with. With increasing urbanization, increasing agricultural area and increasing intensification, natural habitat is not only lost, but also changes its shape and distribution in the landscape. Both aspects can heavily influence an individual's fitness and therefore act as a selective force promoting evolutionary change. This way climate change influences individuals' niches and dispersal. Local adaptation and dispersal are not independent of each other. Dispersal can have two opposite effects on local adaptation. It can oppose local adaptation, by promoting the immigration of maladapted indi- viduals or favor local adaptation by introducing better adapted genotypes. Which of those effects of dispersal on local adaptation emerges in a population depends on the dispersal strategies and the spatial structure of the landscape. In principle an adaptive response can include adjustment of the niche optimum as well as habitat tolerance (niche width) or (instead) ecological tracking of adequate conditions by dispersal and range shifting. So far, there has been no extensive modeling study of the evolution of the environmental niche optimum and tolerance along with dispersal probability in complex landscapes. Either only dispersal or (part of ) the environmental niche can evolve or the landscapes used are not realistic but rather a very abstract representation of spatial structures. I want to try and disentangle those different effects of both local adaptation and dispersal during global change, as well as their interaction, especially considering the separation between the effects of increasing mean and increasing variance. For this, I implemented an individual based model (IBM), with escalating complexity. I showed that both on a temporal as well as on a spatial scale, variation can be more influential then mean conditions. Indeed, the actual spatial configuration of this heterogeneity and the relationship between spatial and temporal heterogeneity affect the evolution of the niche and of dispersal probability more than temporal or spatial mean conditions. I could show that in isolated populations, an increase of an environmental attribute's mean or variance can lead to extinction, under certain conditions. In particular, increasing variance cannot be tracked forever, since increasing tolerance has distinct limits of feasibility. Increasing mean conditions can also occur too fast to be tracked, especially from generalist individuals. When expanding the model to the metapopulation level without a temporal environmental trend, the degree of spatial vs.temporal heterogeneity influenced the evolution of random dispersal heavily. With increasing spatial heterogeneity, individuals from extreme and rare patches evolve from being philopatric to dispersive, while individuals from average patches switch in the opposite direction. With the last expansion to a different set of landscapes with varying degrees of edge density, I could show that edge effects are strong in pseudo-agricultural landscapes, while in pseudo-natural habitats they were hardly found, regardless of emigration strategy. Sharp edges select against dispersal in the edge patches and could potentially further isolate populations in agricultural landscapes. The work I present here can also be expanded further and I present several suggestions on what to do next. These expansions could help the realism of the model and eventually shed light on its bearing on ecological global change predictions. For example species distribution models or extinction risk models would be more precise, if they included both spatial and temporal variation. The current modeling practices might not be suffcient to describe the possible outcomes of global change, because spatio-temporal heterogeneity and its influence on species' niches is too important to be ignored for longer.

Environmental change is multidimensional, with local anthropogenic stressors and global climate change interacting to differentially impact populations throughout a species' geographic range. Within species, the spatial distribution of phenotypic variation and its causes (i.e., local adaptation or plasticity) will determine species' adaptive capacity to respond to a changing environment. However, comparatively less is known about the spatial scale of adaptive differentiation among populations and how patterns of local adaptation might drive vulnerability to global change stressors. To test whether fine-scale (2-12km) mosaics of environmental stress can cause adaptive differentiation in a marine foundation species, eelgrass (Zostera marina), we conducted a three-way reciprocal transplant experiment spanning the length of Tomales Bay, CA. Our results revealed strong home-site advantage in growth and survival for all three populations. In subsequent common garden experiments and feeding assays, we showed that countergradients in temperature, light availability, and grazing pressure from an introduced herbivore contribute to differential performance among populations consistent with local adaptation. Our findings highlight how local-scale mosaics in environmental stressors can increase phenotypic variation among neighboring populations, potentially increasing species resilience to future global change. More specifically, we identified a range-center eelgrass population that is pre-adapted to extremely warm temperatures similar to those experienced by low-latitude range-edge populations of eelgrass, demonstrating how reservoirs of heat-tolerant phenotypes may already exist throughout a species range. Future work on predicting species resilience to global change should incorporate potential buffering effects of local-scale population differentiation and promote a phenotypic management approach to species conservation.

Impacts of global ocean changes on species have historically been investigated at the whole-organism level. However, acquiring an in-depth understanding of the organisms’ cellular metabolic responses is paramount to better define their sensitivity to environmental challenges. This is particularly relevant for species that experience highly different environmental conditions across their distribution range as local acclimatization or adaptation can influence their responses to rapid global ocean changes. We aimed at shedding light on the cellular mechanisms underpinning the sensitivity to combined ocean warming (OW) and acidification (OA) in the northern shrimp Pandalus borealis, from four different geographic origins defined by distinctive environmental regimes in the northwest Atlantic: i.e. St. Lawrence Estuary (SLE), Eastern Scotian Shelf (ESS), Esquiman Channel (EC) and Northeast Newfoundland Coast (NNC). We characterized targeted metabolomics profiles of the muscle of shrimp exposed to three temperatures (2, 6 or 10°C) and two pH levels (7.75 or 7.40). Overall, shrimp metabolomics profiles were modulated by a significant interaction between temperature, pH and origin. Temperature drove most of the metabolomics reprogramming, confirming that P. borealis is more sensitive to OW than OA. Inter-origin differences in metabolomics profiles were also observed, with temperature*pH interactions impacting only shrimp from SLE and ESS, pH affecting only shrimp from SLE and temperature impacting shrimp from all origins. Temperature influenced metabolomics pathways related to the tricarboxylic acid cycle (TCA) and amino acid metabolism, resulting mainly in an accumulation of TCA intermediates and tyrosine. Temperature*pH and pH in isolation only affected amino acid metabolism, leading to amino acids accumulation under low pH. However, the ratio of ATP : ADP remained constant across conditions in shrimp from all origins suggesting that their energetic status is not affected by OW and OA. Still, the accumulation of TCA intermediates and tyrosine suggests the possible enhancement of immune responses under future OW and OA conditions. Our findings suggest that shrimp from SLE are more sensitive at the molecular level, compared to others, to future complex environmental conditions. This underlines the importance of investigating intraspecific variation in mechanisms of responses to combined drivers when trying to define species’ sensitivity to global ocean changes.

Saltwater intrusion risk assessment is a foundational step for preventing and controlling salinization in coastal regions. The Vietnamese Mekong Delta (VMD) is highly affected by drought and salinization threats, especially severe under the impacts of global climate change and the rapid development of an upstream hydropower dam system. This study aimed to apply a modified DRASTIC model, which combines the generic DRASTIC model with hydrological and anthropogenic factors (i.e., river catchment and land use), to examine seawater intrusion vulnerability in the soil-water-bearing layer in the Ben Tre province, located in the VMD. One hundred and fifty hand-auger samples for total dissolved solids (TDS) measurements, one of the reflected salinity parameters, were used to validate the results obtained with both the DRASTIC and modified DRASTIC models. The spatial analysis tools in the ArcGIS software (i.e., Kriging and data classification tools) were used to interpolate, classify, and map the input factors and salinization susceptibility in the study area. The results show that the vulnerability index values obtained from the DRASTIC and modified DRASTIC models were 36–128 and 55–163, respectively. The vulnerable indices increased from inland districts to coastal areas. The Ba Tri and Binh Dai districts were recorded as having very high vulnerability to salinization, while the Chau Thanh and Cho Lach districts were at a low vulnerability level. From the comparative analysis of the two models, it is obvious that the modified DRASTIC model with the inclusion of a river or canal network and agricultural practices factors enables better performance than the generic DRASTIC model. This enhancement is explained by the significant impact of anthropogenic activities on the salinization of soil water content. This study’s results can be used as scientific implications for planners and decision-makers in river catchment and land-use management practices.

The panda lineage dates back to the late Miocene and ultimately leads to only one extant species, the giant panda (Ailuropoda melanoleuca). Although global climate change and anthropogenic disturbances are recognized to shape animal population demography their contribution to panda population dynamics remains largely unknown. We sequenced the whole genomes of 34 pandas at an average 4.7-fold coverage and used this data set together with the previously deep-sequenced panda genome to reconstruct a continuous demographic history of pandas from their origin to the present. We identify two population expansions, two bottlenecks and two divergences. Evidence indicated that, whereas global changes in climate were the primary drivers of population fluctuation for millions of years, human activities likely underlie recent population divergence and serious decline. We identified three distinct panda populations that show genetic adaptation to their environments. However, in all three populations, anthropogenic activities have negatively affected pandas for 3,000 years.

The hydro- and morphodynamic processes within the Vietnamese Mekong Delta are heavily impacted by human activity, which in turn affects the livelihood of millions of people. The main drivers that could impact future developments within the delta are local stressors like hydropower development and sand mining, but also global challenges like climate change and relative sea level rise. Within this study, a hydro-morphodynamic model was developed, which focused on a stretch of the Tien River and was nested into a well-calibrated model of the delta’s hydrodynamics. Multiple scenarios were developed in order to assess the projected impacts of the different drivers on the river’s morphodynamics. Simulations were carried out for a baseline scenario (2000–2010) and for a set of plausible scenarios for a future period (2050–2060). The results for the baseline scenario indicate that the Tien River is already subject to substantial erosion under present-day conditions. For the future period, hydropower development has the highest impact on the local erosion and deposition budget, thus amplifying erosional processes, followed by an increase in sand mining activity and climate change-related variations in discharge. The results also indicate that relative sea level rise only has a minimal impact on the local morphodynamics of this river stretch, while erosional tendencies are slowed by a complete prohibition of sand mining activity. In the future, an unfavourable combination of drivers could increase the local imbalance between erosion and deposition by up to 89%, while the bed level could be incised by an additional 146%.

The shifting season features of precipitation due to the El-Niño and La-Nina events, under the impacts of global climate change (GCC), have increased the potential risks of crop yield decline in rice cultivation areas (CCAs) worldwide. This study examines the relationship between the typical El-Niño and La-Nina phases and the season features of precipitation, and their subsequent impact on CCAs within the Vietnamese Mekong Delta (VMD). Daily rainfall data from 12 observation stations from 1986 to 2022 were analyzed to investigate the connection between ENSO events and season features across the VMD. The results indicate that the El-Niño and La-Nina events significantly influence the timing and duration of season features in the VMD. During the La-Niña event in the period 1999-2001, the rainy season onset date (RSOD) and rainy season cessation date (RSCD) occurred three weeks earlier and two weeks later, respectively, than the long-term average (1986-2022). Conversely, during the extreme El-Niño event of the stage 2014-2026, the RSOD and RSCD were delayed, occurring 10.9 and 5.0 days later than the long-term average, with a shorter length of rainy season (LRS) by 5.9 days over the entire VMD. These shifts in the season features of precipitation under the GCC have impacted cultivation activities in the VMD. The findings underscore the vulnerability of rice cultivation regions in the VMD to ENSO-driven climate variability, emphasizing the importance of proactively implementing adaptation solutions to mitigate the negative impacts of GCC.

Greenhouse gas emission of carbon dioxide (CO2) is one of the major factors causing global climate change. Urban green space presumes a key part in controlling the general carbon cycle and reducing climatic CO2. To Improve the Environment and control the pollution, Green space has become important to diverse Planning concerns that live in the urban environment, to comprehension the part of urban green space in the urban environment. Remote sensing is a well-known tool due to its ability of monitoring urban vegetation rapidly and continuously. This paper asks how should we plan green space? We contend that planners can improve healthier cities for more people by reconsidering three facts of green space planning: Green Space as infrastructure, Green Space as Spaces of everyday life and Green Space as leisure destinations for recreation. The main objective is to build quality infrastructure and more adaptable space throughout the city.

A few studies have evaluated the impact of land use land cover (LULC) change on surface water quality in the Vietnamese Mekong Delta (VMD), one of the most productive agricultural deltas in the world. This study aims to evaluate water quality parameters inside full- and semi-dike systems and outside of the dike system during the wet and dry season in An Giang Province. Multivariable statistical analysis and weighted arithmetic water quality index (WAWQI) were used to analyze 40 water samples in each seasons. The results show that the mean concentrations of conductivity (EC), phosphate (PO43−), ammonium (NH4+), chemical oxygen demand (COD), and potassium (K+) failed to meet the World Health Organization (WHO) and Vietnamese standards for both seasons. The NO2− concentration inside triple and double rice cropping systems during the dry season exceeds the permissible limit of the Vietnamese standard. The high concentration of COD, NH4+ were found in the urban area and the main river (Bassac River). The WAWQI showed that 97.5 and 95.0% of water samples fall into the bad and unsuitable, respectively, for drinking categories. The main reason behind this is direct discharge of untreated wastewater from the rice intensification and urban sewerage lines. The finding of this study is critically important for decision-makers to design different mitigation or adaptation measures for water resource management in lieu of rapid global changes in a timely manner in An Giang and the VMD.

Climate change is underway and the rising of oceans and frequency of destroying floods have gone on already in a considerable way. The level and the waves of the oceans threaten the coastlines. Especially in river districts of many countries we have to note the worst cases of floods. On the other hand, mankind is growing more and more and the right of adequate housing and sufficient space too. In this situation floating houses and floating settlements in coastal regions and flood plains could be the basis for a sustainable city in the future worldwide. Let us look for a local climate adaption. In this context, a lot of topics must be researched: environmental problems, energy supply, disposal, measurements of boundary conditions (climate and water quality), damage to floating homes, development of new materials, the use of pontoon’s volume as a housing or technique room and for storage of energy, goods and materials. Besides climate change, other global changes, such as the migration of people, animals and plants or the influences of industrial and financial activities should be considered too.

The article examines the development and formation of the architecture of modern rehabilitation centers within the structure of the existing urban environment as innovative polyfunctional facilities. Particular attention is given to the aspects and trends in the formation of contemporary rehabilitation centers, their spatial characteristics, specific features, and patterns of development within the structure of large cities. The article defines the meaning of terms and concepts related to rehabilitation centers and the formation of modern health-promoting spaces in the existing urban environment. It is established that modern rehabilitation centers and new health-oriented spaces play a crucial role in developing the urban environment. Their goal is to stimulate socially adaptive physical activity spaces, emphasizing the concepts of sustainable architecture, inclusion, ergonomics, environmental sustainability, and landscape integration. Additionally, it is noted that in the context of global changes, military conflicts, and emotional challenges, rehabilitation and wellness centers are becoming increasingly significant in architectural practice. Such polyfunctional facilities contribute to the creation of social spaces for integration into society, adaptation, socialization, and rehabilitation of urban residents, aiming to restore fundamental human experiences such as a sense of belonging, unity, and mutual understanding. This article analyzes the scientific and practical experience of rehabilitation center development, highlighting the importance for professional architects of regulating existing (adaptation or restoration) and developing new health-oriented spaces within the urban structure. The study explores rehabilitation center formation's specifics, characteristics, and regularities, including planning elements, spatial organization, and functional content. It is determined that these centers can be located both within cities and in natural environments outside urban areas. They are equipped with sports facilities, swimming pools, recreational spaces, cinemas, and other amenities. Thus, the development of rehabilitation centers stimulates social potential, promotes healthy social integration, and underscores the urgent need for a nationwide network of such facilities. The active growth of rehabilitation centers serves as a foundation for improving public health and is an essential component in shaping the modern appearance of cities, ensuring a harmonious integration of all elements of a cohesive urban environment.

In this study, we assessed the impact of sea level rise, one of the most ascertained consequences of global climate change, for water levels in the Vietnamese Mekong Delta (VMD). We used a hydraulic model to compute water levels from August to November - when flooding is presently critical- under sea level rise scenarios of 20 cm (=Δ 20) and 45 cm (=Δ 45), respectively. The outputs show that the contour lines of water levels will be shifted up to 25 km (Δ 20) and 50 km (Δ 45) towards the sea due to higher sea levels. At the onset of the flood season (August), the average increment in water levels in the Delta is 14.1 cm (Δ 20) and 32.2 cm (Δ 45), respectively. At the peak of the flood season (October), high discharge from upstream attenuates the increment in water level, but average water level rise of 11.9 cm (Δ 20) and 27.4 cm (Δ 45), respectively, still imply a substantial aggravation of flooding problems in the VMD. GIS techniques were used to delineate areas with different levels of vulnerability, i.e., area with high (2.3 mio ha =60% of the VMD), medium (0.6 mio ha = 15%) and low (1 mio ha =25%) vulnerability due to sea level rise. Rice production will be affected through excessive flooding in the tidally inundated areas and longer flooding periods in the central part of the VMD. These adverse impacts could affect all three cropping seasons, Mua (main rainfed crop), Dong Xuan (Winter-Spring) and He Thu (Summer-Autumn) in the VMD unless preventive measures are taken.

Modeling of hydrodynamics and sediment transport in the Mekong Delta

The article discusses the main effects of climate change on socio-economic processes in the coastal areas of Vietnam.As the climate continues to change, millions of people face growing challenges related to extreme events that affect health, economies, migration and forced displacement and other associated risks. Vietnam is one of the first countries to acutely feel the effects of global climate change. It is coastal areas, such as the Mekong Delta in the first place, that are subjected to devastating floods and tropical cyclones every year, causing enormous economic damage and causing the need to relocate large numbers of people. As a country heavily affected by climate change, Vietnam has come up with many solutions to adapt to climate change and minimize the impact of climate change. Viet Nam is also one of the first developing countries in the world to include a commitment to reduce greenhouse gas emissions in the legal system for the entire population to comply with. Gradual climate events such as rising temperatures and rising sea levels affect livelihoods and can lead to long-term migration. This article analyzes the impact of global climate change on Vietnam, namely coastal areas. Coastal areas can be a powerful engine for Vietnam's further economic and social development, but rapid urbanization, economic growth and climate change mean that disaster risks will inevitably increase in the future. The socio-economic consequences of global climate change are determined, in particular for the coastal regions of Vietnam. Attempts to respond to global climate change are presented. To date, the region has implemented many policies and programs related to climate change.

The purpose of this study is to conduct an economic valuation of creating a concrete sea dike system as an adaptation measure to counter the impacts of a rise in sea level using a risk cost-benefit analysis framework. It uses an ex-ante approach with risk considerations for storms, floods, and salinity by specifying probability distribution functions in a simulation process, in order to incorporate these risk factors into the analysis. The results showed that the benefits of storms and floods avoided dominated the dike options. The benefit of salinity avoided was also valuable, with annual rice and aquaculture productivity losses avoided of USD 331.25 per ha and USD 915 per ha, respectively. This study evaluated a range of dike options to adapt to climate change in the Vietnamese Mekong Delta, showing high levels of benefits compared to costs. The larger in scale the dike system options were, the higher the expected net present values (ENPVs) were. Of the dike alternatives applicable to the Vietnamese Mekong Delta, considering the impacts of sea level rise of storms, floods and raised salinity in soil from flooding, small scale dikes that can subsequently be increased in height should be a priority choice. The sensitivity analyses showed that the ENPVs of dike options were very sensitive with changes in discount rate but were not sensitive with increases in salinized areas at all. The findings provide evidence to support the necessity of the construction of a concrete sea dike system in the Vietnamese Mekong Delta, given the context of global climate change.