Decades Of Monitoring Research Articles

Impact of hydrogeology factors on geotechnical conditions of the heritage Kyiv-Pechersk Lavra Monastery complex: Lessons from three decades of monitoring

Abstract The architectural ensemble of the Kyiv-Pechersk Lavra monastery located in the city of Kyiv on the Right Bank of the Dnipro River, which represents historical and cultural heritage of world significance, suffers from a wide range of hazardous geological processes. The review and analysis of data of the long-term (since the 1990s) groundwater monitoring studies of the Kyiv-Pechersk Lavra shows that hydrogeological hazards caused by a complex combination of natural and anthropogenic factors (as well as sometimes by engineering miscalculations) have led to a significant number of emergency situations that threaten the heritage architectural monuments. Monitoring data illustrate a wide range of hydrogeological hazards (flooding, subsidence, landslides, suffusion), and emphasize the importance of consideration of hydrogeological aspects for safeguarding architectural monuments in the urbanized context. The paper also summarizes experience in engineering measures aimed at mitigating of hydrogeological hazards and discusses the pending research tasks

Two decades of monitoring in Mauritania

Two decades of monitoring in Mauritania

Mapping air quality trends across 336 cities in India: Insights from three decades of monitoring (1987–2019)

Over a span of 34 years (1987–2019), an in-depth analysis of PM10, SO2, and NO2 trends across India was conducted using data from the National Ambient Air Quality Monitoring Programme’s manual monitoring stations in 336 cities. The study encompassed six geographical regions over three time blocks, revealing a correlation between the expansion of monitoring networks and the nation’s economic growth. Regions like the densely populated Indo-Gangetic Plains (IGP) and Central India consistently hosted more monitoring stations, while the Himalayan and Northeast regions saw substantial increases from initial scarcity. SO2 concentrations showed a declining trend, while NO2 levels remained relatively stable with intermittent fluctuations. Conversely, national average PM10 concentrations exhibited an upward trajectory, notably spiking by 128 % between 2006 and 2009 due to economic activities, construction, network expansion, the 2009 drought, and heightened coal consumption. Spatially, pollutant concentrations across three blocks demonstrated improved SO2 levels, several cities exceeding NO2 standards, and persistently high PM10 levels in the IGP. PM10 levels in block 3 were lower than in block 2, reflecting effective policy interventions. State rankings, however, did not consistently reflect pollutant trends across blocks. Regionally, the IGP consistently had the highest PM10 concentrations, while the Northeast recorded the lowest. Population-weighted exposure levels indicated an overall increase in public exposure to PM10. Analysis of major city per region aligned with national trends, as evidenced by Delhi (IGP), Guwahati (Northeast), Vadodara (Northwest), and Bhopal (Central) showing increased PM10 concentrations since 2006, followed by intermittent declines. In contrast, Shimla (Himalayan) and Chennai (Southern) exhibited distinct patterns. Major industrial cities such as Parwanoo, Bongaigaon, Angul and Talcher, and Visakhapatnam mirrored national trends, with PM10 levels rising since 2009, highlighting the significant impact of industrial activities on air quality. This research underscores the need for targeted, effective mitigation strategies based on spatial and temporal pollutant trends.

Patterns in Fish-Assemblage Structure Over a Decade of Monitoring in the Upper Delaware River Watershed

Patterns in Fish-Assemblage Structure Over a Decade of Monitoring in the Upper Delaware River Watershed

Polychlorinated biphenyls in mussels, small pelagic fish, tuna, turtles, and dolphins from the Croatian Adriatic Sea waters: an overview of the last two decades of monitoring.

This review summarises our two decades of polychlorinated biphenyl (PCB) monitoring in different marine organisms along the eastern Adriatic Sea. The aim was to gain an insight into the trends of PCB distribution in order to evaluate the effectiveness of past and current legislation and suggest further action. Here we mainly focus on PCB levels in wild and farmed Mediterranean mussels, wild and farmed bluefin tuna, loggerhead sea turtles, common bottlenose dolphins, and small pelagic fish. The use of artificial intelligence and advanced statistics enabled an insight into the influence of various variables on the uptake of PCBs in the investigated organisms as well as into their mutual dependence. Our findings suggest that PCBs in small pelagic fish and mussels reflect global pollution and that high levels in dolphins and wild tuna tissues raise particular concern, as they confirm their biomagnification up the food chain. Therefore, the ongoing PCB monitoring should focus on predatory species in particular to help us better understand PCB contamination in marine ecosystems in our efforts to protect the environment and human health.

Nearshore fish community changes along the Toronto waterfront in accordance with management and restoration goals: Insights from two decades of monitoring.

Aquatic habitat in the Greater Toronto Area has been subject to anthropogenic stressors. The subsequent aquatic habitat degradation that followed led to the Toronto and Region waterfront being listed as an Area of Concern in 1987. Thus, extensive shoreline and riparian habitat restoration have been implemented as part of the Toronto and Region Remedial Action Plan in conjunction with local stakeholders, ministries, and NGOs in an overall effort to increase fish, bird, and wildlife habitat. A key aspect of current fish habitat restoration efforts, monitored by Toronto and Region Conservation Authority, is to account for long-term community changes within the target ecosystem to better understand overall changes at a larger spatial scale. Here we use electrofishing data from the past 20 years with over 100,000 records and across 72km of coastline to show how declines and fluctuations in fish biomass and catch along the waterfront are driven by a few individual species across three main ecotypes, such as coastal wetlands, embayments, and open coast sites, with the remaining species showing a high level of stability. Using community traits and composition for resident species we demonstrate native warmwater species have become more dominant along the waterfront in recent years, suggesting that restoration efforts are functioning as intended. Additionally, piscivore and specialist species have increased in their relative biomass contribution, approaching existing restoration targets. Altogether this waterfront-wide evaluation allows us to detect overall changes along the waterfront and can be beneficial to understand community changes at an ecosystem level when implementing and monitoring restoration projects.

Life History of the Andean Condor in Ecuador

Background and Research Aims: Little information exists on the breeding behavior of the Andean Condor ( Vultur gryphus). Its global population, estimated at 6700 adult individuals, is declining throughout its distribution range. With less than 150 condors, the Endangered condor population in Ecuador is of conservation concern. This study aimed to analyze the breeding behavior of wild-born Andean Condors in Ecuador. Methods: Between 2009 and 2021, we monitored 22 egg-laying attempts in eight Andean Condor nests, evaluated the parental care of three breeding pairs of condors and recorded the species' interactions with other raptors and mammals during the nestling-rearing season, and examined the breeding success of an Andean Condor pair during a decade of monitoring. Results: Our breeding records indicated that Andean Condor lay eggs throughout the year, and 16 nestlings spent between six and 10 months in the nest before making their first flights. We found differences in the length of time that the parents remain with the nestling, and described agonistic encounters between condors and other raptors and a Spectacled Bear ( Tremarctos ornatus) in the condor nesting areas. The breeding success of the monitored condor pair was 0.88 nestlings per clutch, and the female laid an egg on average every 15 months. Conclusion: Considering the small size of the Andean Condor population in Ecuador, studies on the breeding behavior of wild-born condors are a high research priority to assess population trends and prevent extinction. Specifically, we recommend further research on parental care, breeding success, nestling survivorship, and nesting phenology. Implications for Conservation: Beyond the importance of the protected area system, strategic planning of key areas for the maintenance of condor populations in the northern Andes must encompass the evaluation of new potential protected areas that offer direct benefits to these birds. These should include nesting sites in human-dominated landscapes such as rural Andean areas.

Environmental state of a small intertidal estuary a decade after mangrove clearance, Waikaraka Estuary, Aotearoa New Zealand

Unlike many parts of the world, mangrove coverage has been steadily increasing in Aotearoa,New Zealand since the 1900s. Intentional mangrove removal in Aotearoa New Zealand is often motivated by a desire to remove muddy sediment from sites that were once sand-dominated. Mangrove removal can result in geomorphic and ecologic evolution over decadal timescales, yet monitoring of removal sites is often limited to a few years. This study presents the result of over a decade of monitoring in Waikaraka Estuary, a quiescent embayment where mangroves were removed between 2003 and 2012. Surface elevation was monitored between 2006 and 2019, and sediment cores and surface samples collected in 2019 were analysed for grain size, total organic content, and root biomass to assess geomorphic change. Remaining mangroves areas and benthic macrofauna were surveyed throughout the estuary to assess ecologic change. Despite initially rapid movement of mud out of cleared areas, the estuary has experienced little bed-elevation change over a decade. The upper estuary remains muddy, and much of the root biomass has not decomposed. However, the region near the mouth of the estuary has become sandier with the return of bivalve species Austrovenus stutchburyi (cockles) and Macomona liliana. These long-term measurements demonstrate the slow pace of recovery following mangrove removal in quiescent embayments. Without major changes to hydrodynamics, mud is unlikely to be flushed out and bivalve habitat is unlikely to be restored even after a decade. Site-specific characteristics should be assessed when evaluating the efficacy of mangrove removal for estuary restoration, to moderate community expectations.

Multi-decadal shoreline mobility of a managed sandy tidal coast (Normandy, France): Behavioural variability in a context of sea-level rise and increasing storm intensity

A unique dataset of 27 years of shoreline changes along the western coast of Cotentin Peninsula (Normandy, France) with a high temporal resolution (about 60 fields surveys) provides an opportunity to analyse the space and time variability of a tidal sandy wave-exposed shoreline and to identify the main drivers of this variability. Spatially, as often observed around the world, this coast shows a clear balance between erosional and accretionary sectors. Maximum shoreline retreat and mean annual erosional rates are, however, greater by a factor of two than maximum and mean accretion rates, with hotspots mainly observed in the vicinity of tidal inlets. A cluster analysis highlighted nine groups of shoreline behaviour that show important contrasts, depending on locations, between erosional and accretionary trends. Linear trends over the nearly three decades of monitoring are uncommon and reverse trends are frequent. Clear divergences in behaviour were observed over the same time periods depending on location, e.g., erosion and accretion can be contemporaneous as can accretion and stability, independently of the antecedent multi-annual trends. Ebb delta zones show heterogeneous patterns, and survey locations belonging to the same clusters appear spatially scattered. The temporal shoreline behaviour can be linked to combinations of high wave energy and high spring tides only for at best 37.5% of the survey locations, and this only over the last decade. No obvious link with mean sea-level rise and the 18.6 y lunar tidal cycle was observed. However, as in the case of wave activity, these external drivers can often be masked by local factors such as inlet dynamics or/and anthropogenic influences (essentially shoreline engineering). Further insight on sand supply and beach elevation changes is necessary to improve the understanding of the main factors driving space and time variability in shoreline mobility, and it is expected that sea-level rise in the future will be of increasing concern, with important, potentially negative, implications for shoreline mobility on the low sandy sectors of the Normandy coast.

Long‐Term, High‐Resolution Permafrost Monitoring Reveals Coupled Energy Balance and Hydrogeologic Controls on Talik Dynamics Near Umiujaq (Nunavik, Québec, Canada)

AbstractRising temperatures in the Arctic and subarctic are driving the rapid thaw of permafrost by reducing permafrost cooling, increasing active layer thickness, and promoting talik formation. In this study, the cyrohydrogeology of a permafrost mound located within the discontinuous permafrost zone near Umiujaq (Nunavik, Québec, Canada) is characterized through the analysis of a dataset covering more than two decades of monitoring. This dataset captures a high degree of interannual variability in air temperature and ground thermal conditions, as well as the formation and closure of a supra‐permafrost talik. Data indicate that variable saturation and advective heat transport directly contribute to the expansion and contraction of the talik. Data further indicate the presence of two distinct thermo‐hydrologic settings resulting from differences in surface conditions, as well as subsurface thermal and flow regimes. The first, found at the top of the mound feature, is characterized by very low moisture contents (<0.05 m3/m3), while the second, found at the side of the mound feature, shows higher annual moisture contents that strongly influence the dynamics of heat and groundwater flow. The data were synthesized into a detailed conceptual model of the cyrohydrogeological dynamics that highlights the important role of hydrogeological characterization and long‐term data sets in understanding the effects of groundwater flow on seasonal frost and permafrost dynamics. Specifically, the results presented here show that in the absence of long‐term data sets, longer‐period transient phenomena such as talik opening and closure may be misrepresented as uni‐directional feedback loops, as opposed to highly dynamic temporary phenomena.

Primarily neutral effects of river restoration on macroinvertebrates, macrophytes, and fishes after a decade of monitoring

Restoring river habitat heterogeneity is expensive and time consuming, yet often has little effect on aquatic biota. Such poor restoration outcomes could be partly caused by the predominance of short‐term studies, which do not account for natural temporal fluctuations nor changes in the effects of restoration through time. Consequently, research that examines the longer‐term dynamics of river restoration is crucial for providing a temporal perspective of restoration outcomes and for informing the effectiveness of restoration methods. We used the Nidda River in Germany as a case study of the temporal effects of river hydromorphological restoration on different aquatic taxa. We surveyed macroinvertebrate, macrophyte, and fish communities across three sites prerestoration (2008) and then monitored changes in one control versus two restored sites across 10 years (2010–2019). Overall, we found few effects of restoration on the macroinvertebrate and macrophyte communities, with no effects whatsoever on fishes. Restoration improved some components of the macroinvertebrate and macrophyte communities; however, these positive effects were temporally inconsistent and did not translate to improvements in river ecosystem health (based on an index of ecological quality). Our findings illustrate how allowing for more time for community development will not necessarily alter the fact that local‐scale river habitat restoration can elicit little to no change in aquatic communities. Combining local‐ with broad‐scale restoration efforts that address the primary drivers of hydroecological decline, in addition to long‐term monitoring, may therefore be required to ensure that river restorations successfully meet their ecological goals.

On the recurrence times of neutron star X-ray binary transients and the nature of the Galactic Centre quiescent X-ray binaries

ABSTRACT The presence of some X-ray sources in the Galactic Centre region which show variability, but do not show outbursts in over a decade of monitoring has been used to argue for the presence of a large population of stellar mass black holes in this region. A core element of the arguments that these objects are accreting black holes is the claim that neutron stars (NSs) in low-mass X-ray binaries (LMXBs) do not have long transient recurrence times. We demonstrate in this paper that about half of the known transient LMXBs with clear signatures for NS primaries have recurrence times in excess of a decade for outbursts at the sensitivity of MAXI. We furthermore show that, in order to reconcile the expected total population of NS LMXBs with the observed one and with the millisecond radio pulsar (MSRP) population of the Galaxy, systems with recurrence times well in excess of a century for outbursts detectable by instruments like MAXI must be the dominant population of NS LMXBs, and that few of these systems have yet been discovered.

Sea ice extent and phenology influence breeding of high-Arctic seabirds: 4 decades of monitoring in Nunavut, Canada.

Seabirds breeding in the high Arctic contend with variable annual sea ice conditions, with important consequences depending on a species' unique reproductive and foraging ecology. We assessed the influence of sea ice extent and phenology on seabird breeding biology using monitoring data collected for northern fulmar (Fulmarus glacialis), glaucous gull (Larus hyperboreus), black-legged kittiwake (Rissa tridactyla), and thick-billed murre (Uria lomvia) breeding at Prince Leopold Island, Nunavut, Canada over 4 decades. We expected that years of later sea ice break-up and greater ice cover around the colony would create greater challenges to foraging and could result in delayed nest initiation, decreased colony attendance, and lower nesting success, but with distinct responses from each species. We also tested for time-lagged effects of ice conditions, where sea ice in a given year could impact food availability or juvenile recruitment in later years. Ice conditions around the colony exhibited no significant overall temporal trends or changepoints over the past 50years (1970-2021), while counts of kittiwakes and murres increased over the study period 1975-2013. No trends were evident in counts of fulmars or gulls or in egg-laying dates or nest success for any species. However, three species (all but glaucous gulls) exhibited unique responses between breeding metrics and sea ice, highlighting how breeding decisions and outcomes may differ among species under the same environmental conditions in a given year. Time-lagged effects were only detected for kittiwake nest counts, where the date of spring ice break-up around the colony was negatively associated with counts at a 5-year lag. Greater distances to open water were associated with lower colony attendance by fulmars and later nest initiation by kittiwakes and murres. Our analyses provide additional insights to effects of sea ice on high-Arctic seabird breeding ecology, which will be useful in predicting and planning for the complex effects of a changing climate and changing human pressures on this high-latitude ecosystem and for the management of high-Arctic marine-protected areas.

Condition Assessment of August A. Busch Bridge Deck Using Portable Seismic Property Analyzer and Ground Penetrating Radar

Ground penetrating radar (GPR) and the portable seismic property analyzer (PSPA) have been extensively used in the past two decades for monitoring, quantifying, and mapping the deterioration of bridge decks. Using PSPA and GPR ensures regular monitoring of bridge conditions, leads to the early detection of deterioration. This research is to address the condition of August A. Busch bridge deck owned by the Missouri Department of Conservation. Visual inspection, GPR, and PSPA data were acquired on the bridge deck. Over 90% of the bridge deck was in fair to good condition with an average compressive strength of over 2500 psi. GPR data showed no indication of significant deterioration. The overall bridge deck was determined to be in fair to good condition.

Progress or Regress? A Systematic Review on Two Decades of Monitoring and Addressing Land Subsidence Hazards in Semarang City

Land subsidence is a major cause of environmental degradation. It increases the exposure of global sea level rise-related disasters in coastal cities lying on young sediment. Ample monitoring, adaptation, and mitigation measures have been taken to tackle the impact of such coastal hazards for decades in Semarang City. However, to date, land subsidence still has a negative impact on people’s quality of life. This brings us to the question of whether the measures are progressing towards better management or going to the opposite side. This paper is aimed to answer that question through an extensive literature review using PRISMA Guidelines to 125 scholarly articles and quantitative supporting analysis. We found that land subsidence is overlooked. Although the monitoring measures are progressing towards better technology utilization, it was not properly integrated into mitigation and adaptation measures. Instead of investing more on developing better urban water management, groundwater extraction still became the preferred water source. Thus, there is a major shift needed with regard to urban activities that need to pay more heed to the environment.

Monitoring and analysis of the exceptional displacements affecting debris at the top of a highly disaggregated rockslide

The activity of large rockslides is dependent on a combination of interplaying factors that control strain localization within the slope. In some cases, continued deformation may lead to widespread disaggregation of the slide mass (i.e., loss of cohesion and development of debris). Layers with markedly different composition and strength may eventually form, making it difficult to assess the actual nature of hazards and related risks posed to the valley bottom. This paper provides updated insights into the highly disaggregated and rapidly evolving Ruinon rockslide (Central Italian Alps) based on more than a decade of monitoring by means of a Ground-Based Interferometric Synthetic Aperture Radar (GBInSAR). The rockslide was recently affected by a prolonged period of exceptional surface velocities—consistently exceeding 1 m/day. Monitoring data are examined in order to estimate the thickness of the rapidly moving layer of upper chaotic debris by means of the balanced cross-section method as well as determine the effects of hydrological forcing on the slope displacements. Finite-element modelling is then used to derive hypotheses concerning the deformation behavior of the slide mass at greater depth and different elevations. It is suggested that the upper debris moves at rates several orders of magnitude higher than the underlying substrate, and that in relative terms the sensitivity to sliding of the two layers is similarly governed by the increase of piezometric levels in the spring/summer. On lower slopes, the activity of the upper debris appears to be also influenced by precipitation events that are not accompanied by a notable increase of the piezometric levels measured at the rear of the slide. Our findings show the importance of implementing long-term GBInSAR monitoring at challenging sites like Ruinon, where fieldwork and installation of instruments on the slide mass are not feasible.

Trends in Meeting the Physical Activity Guidelines: Muscle-Strengthening Alone and Combined With Aerobic Activity, United States, 1998-2018.

The National Health Interview Survey is unique among US federal surveillance systems with over 20 years of consistent assessment of muscle-strengthening and aerobic activity. The authors examined trends in the prevalence of US adults who met the muscle-strengthening (2 or more days per week) and the combined muscle-strengthening and aerobic physical activity (at least 150min/wk of moderate-intensity equivalent activity) guidelines from 1998 to 2018. The 1998-2018 National Health Interview Survey data were analyzed. Age-adjusted prevalence of meeting the muscle-strengthening and combined aerobic and muscle-strengthening guidelines by selected respondent characteristics were estimated for each year and linear and higher-order trends were assessed. From 1998 to 2018, prevalence of meeting the muscle-strengthening guideline increased from 17.7% to 27.6%, and meeting the combined aerobic and muscle-strengthening guidelines increased from 14.4% to 24.0%. All subgroups demonstrated significant increases in meeting both guideline measures over this period although trends varied across the 21 years; increasing trends were more commonly sustained in the second decade of monitoring. Although increasing trends in prevalence of meeting the muscle-strengthening and combined guidelines are encouraging, current prevalence estimates remain low. Opportunities exist for the continued promotion of muscle-strengthening activity using evidence-based approaches.

The influence of natural vs anthropogenic factors on trace metal(loid) levels in the Mussel Watch programme: Two decades of monitoring in the Spanish Mediterranean sea

The spatial distribution and temporal trends of trace metals (i.e. Cd, Cu, Hg, Pb and Zn) and a metalloid (i.e. As) along the Spanish Mediterranean coast from 1993 to 2013 are presented with a new estimation of their background levels monitored using wild mussels. Over a 20 years period, yearly mussel monitoring was undertaken with a rigorous field sampling protocol using 3 pooled samples strategy (3 x n = 80, with 8 mussels in the 3.0 to 3.9 size categories at each site), obtained in the pre-spawning period (May–June) to minimize biological factors and seasonal variability, which is a fundamental element of the international programme. Spatial distribution was characterized every 5 years and temporal trends were determined in 11 locations. The main aims of the present long term study are to evaluate the environmental status of different coastal locations regarding trace metal levels and follow the evolution of these levels over time after the implementation of regulatory measures. Regarding spatial distribution, the highest values for Cd, Cu, Hg and Pb were found close to known highly anthopogenic cities or shipyard areas. However, As and Zn did not strictly follow this pattern, showing natural increased concentrations in the Levantine Balearic and Strait of Gibraltar-Alboran Sea demarcations respectively. These distributions are associated with the conjunction of two geological formation inputs (Massif Central in France and Iberian Pyritic Belt in Spain) and the oceanographic conditions in the adjacent coastal area. In the case of temporal trends, metal concentrations decreased significantly over time in most stations, confirming the effectiveness of the regulatory measures and prohibitions established under European legislation. Concentrations of Pb were above the established thresholds for human consumption in only 12–14% of the sampling areas. With the information obtained for this study, we estimate background concentrations and propose new Background Assesment Criteria (BAC) for the Spanish Mediterranean coast as a threshold criterion: 1.62 mg/kg d.w. for Cd, 8.75 mg/kg d.w. for Cu, 0.202 mg/kg d.w. for Hg and 2.83 mg/kg d.w. for Pb.Exceptions should exist for As and Zn, for which there should be different levels in each demarcation, due to the geological, hydrological and oceanographic peculiarities of the Spanish coast. For the Levantine-Balearic demarcation, the proposed background concentrations are 117 mg/kg d.w. for As and 200 mg/kg d.w. for Zn., whereas in the Strait of Gibraltar-Alboran Sea demarcation, they are 27.5 mg/kg d.w. for As, and 471 mg/kg d.w. for Zn. This work demonstrates the vital importance of defining the background levels of metal(loid)s at a regional or subregional level because, for areas not affected by anthropogenic causes which have high values as the result of natural processes, this would avoid the risk of constantly surpassing the levels proposed in directives.

The changing role of natural and human agencies shaping the ecology of an African savanna ecosystem

AbstractReconstructing the historical interplay of wildlife and pastoralists in the African savannas is clouded in contemporary studies by the transformation of subsistence societies and land use changes. We draw on five decades of monitoring by the Amboseli Conservation Program to illustrate the rainfall–plant–herbivore linkages in a free‐ranging wildlife–livestock system transitioning to contemporary savanna landscapes. In half a century, the coupled interactions of wildlife and livestock in the Amboseli ecosystem driven by rainfall and water sources have been severed and reshaped by farming, land subdivision, sedentism, poaching, and intensified herbivory. Livestock ranges have expanded, wildlife ranges have contracted, and overlapping spatial use has fluctuated with population sizes. In contrast, wildlife and livestock herds have been sustained where the rangelands remain open. A decrease in the mean body size reflecting a shift to small stock among pastoralists has increased species dominance, decreased diversity, and elevated biomass turnover and the probability of extreme shortfalls. In recent droughts, pastoralists have been importing food supplements to reduce drought risk and purchased livestock to restock herds, further uncoupling the rainfall‐herbivore link. Our study reinforces the view that biomes worldwide are shaped at an accelerating pace by human agencies rather than endogenous environmental factors. Disputes over models of rangeland systems echo the wider debate over using natural ecosystems as benchmarks for conservation verses “gardening” nature. We argue that models of natural ecosystems fail to account for the dominant role of humans in contemporary ecosystem yet that it is possible to monitor the complex interplay of human and natural systems and interpret the changes in terms of ecological function using macroecological analysis. The key finding for conservation is the importance of space, landscape heterogeneity, social networks, and mobility in sustaining the large herbivore populations.

Spatial and temporal changes of dissolved oxygen in waters of the Pajarales complex, Ciénaga Grande de Santa Marta: Two decades of monitoring

Ciénaga Grande de Santa Marta lagoon complex, located in the Colombian Caribbean, is a highly degraded estuarine system, in which massive deaths of organisms have occurred since the 1990s, causing socioeconomic effects on the inhabitants, who are mostly artisanal fishermen. These deaths have been attributed to the deoxygenation of the water at night, as a result of the eutrophication of the system. To understand the variability of dissolved oxygen and its relationship with other water quality variables, the monthly time series collected between 2001 and 2019, in seven stations of the Pajarales Complex (western side of the estuarine complex), were analyzed. Analyzes showed that there are significant differences between stations, as well as between the surface and the bottom of the water, indicating that the behavior of oxygen in the system is not homogeneous, a product of the hydrodynamics of the system. Also, temporal differences were found related to the periods of rain and drought, even with larger-scale climatic events such as El Niño and La Niña, with the lowest concentrations being recorded during the rainy seasons. On the other hand, the analysis of the time series of the average surface temperature of the seven stations analyzed showed a slight tendency to increase over time. Results indicate that the system is very dynamic and its oxygenation conditions are determined by climatic factors that promote changes in water chemistry, such as variations in salinity, temperature, and pH, and biological activity, determined by the abundance of the organisms. Analysis of this information becomes a tool to propose an alert system that allows reducing the impact of deaths.