Anthropogenic Impact on Lake Ecosystem

Abstract

The world’s population growth in various ways impacts the waters environment, and these impacts have been observed since the twentieth century. However, paleolimnological data indicates that anthropogenic activities have been affecting the aquatic ecosystem for a long time ago. The primary determinant of the lake ecosystem damage is the change and utilization of the catchment area landscapes, which contributes to siltation as well as nutrient supply. The increased activities of agriculture and domestic work are the main causes of eutrophication due to nutrient input. Additionally, the cage aquaculture in the lake waters has led to oxygen depletion in the lower water column as an impact of organic loading input. Furthermore, habitat modification, including disturbance to the shore zone, has led to changes in riparian areas. Ultimately, these processes impact the biota population structure and degrade the lake ecosystem. Therefore, understanding the anthropogenic factors and their impact on the lake ecosystem will enable humans to control their activities and manage their impact on the ecosystem.

1. Introduction

All human efforts in exploiting and modifying the environment are anthropogenic activities that significantly impact the environment and tend to have negative consequences. To manage these impacts, it is important to distinguish between environmental and anthropogenic factors’ influence and understand how they affect human survival and well-being. This understanding is crucial for controlling the threats that humans face. Unfortunately, humans are often their own worst enemy when they are the main cause of pollution and environmental damage. While the cumulative effect from natural events on the environment is much smaller than the problems caused by human activities [1].

Over time, it has become increasingly apparent that human activities in various fields have caused a significant imbalance in the ecological system, leading to environmental disruption, and affecting human life. The negative impacts on our environment resulting from continued population growth accompanied by economic development cannot be overlooked. Therefore, it is crucial to analyze environmental conditions such as water, air, and soil, and observe the primary sources of pollution. The hope is that this analysis will minimize the impacts, regardless of where and when it occurs. Sustainable development is becoming more important as the “blue economy” concept raises awareness of the adverse effects of industrial and agricultural practices on the environment. Consideration of ecological factors gets more attention, not merely economic ones. Thus, anticipatory measures will likely be taken to address the influence of anthropogenic activities and their impact on the environment [2].

Human activities significantly impacted the environment. Figure 1 illustrates that the impact curve continues to increase with time in line with the anthropogenic activity rate, and time a peak curve pattern will reach, indicating when anthropogenic activity’s impact begins to be controlled. The timing of this peak varies significantly for each country, highlighting the need for tailored solutions to address environmental issues on a local level [3]. While it is widely acknowledged that environmental damage was severe in the twentieth century, paleolimnological records indicate that anthropogenic activity and its impact on lake waters occurred much earlier than previously thought [4].

Figure 1.

General development stages of human disturbance factors to the environment in industrialized countries [3].

Despite various mitigation efforts, especially wastewater management, other environmental impacts are still visible. One such impact is the alteration of waters morphology, increased turbidity caused by eutrophication, and the loss of biodiversity. This is a major problem in many parts of the world. Inland waters, such as lakes, are susceptible to anthropogenic impacts. As human populations grow and agricultural and industrial activities expand, aquatic ecosystems are increasingly threatened. This puts pressure on these ecosystems, and urgent action is needed to address the negative impacts on our water resources.

As economic growth has continued, humans have altered Earth’s biodiversity and ecosystems, decreasing the use value of ecosystem services. This biodiversity loss is driven by the need for various resources for human survival, which is likely to continue [5]. With a population of over 7 billion people and a rapid increase in per capita consumption of goods and services, the visible ecological footprint of human growth is changing land cover, rivers, climate systems, biogeochemical cycles, and ecosystem functions. However, historically, human attention to environmental health has been more focused on the quantitative response of the relationship between pollutant exposure and human health. More recent research has shed light on how changes in the structure and function of natural systems can also impact human health in various ways. This perspective is becoming increasingly important as the rate and extent of these changes continue to accelerate [6].

To achieve a harmonious balance between human life and nature and prevent the negative impacts of human activities, it is crucial to disclose the hidden potential of basic science. This will help us transition towards a better environment for all [7]. Furthermore, it will enable us to maximize the socioeconomic and bio-cultural benefits to improve human quality of life [8].

2. Paleolimnological review

The sediments store the lake’s history, the lake waters state, the catchment area environment, and climatic conditions. Interpretation of past situations is recorded in sedimentary structures and mineralogy, their organic and inorganic chemical components, and the morphological remains of organisms stored in them. The history of the lake can show the change in ecosystem condition, both their saprobic state and productivity. Interpreting critical records is needed to see the variable factors of the drainage basin, redistribution of sediments, and variations in the preservation of the interpreted components [9].

Paleolimnological analysis, as a study of the history of lakes in terms of physical, chemical, and biological information preserved in sediments, is an approach to understanding both natural and anthropogenic changes in the past. The palaeoecological approach is a crucial tool for understanding the long-term ecological condition of lakes, including how human activities and climate change affect these ecosystems. While natural forces such as volcanic eruptions and climate change can impact lake ecosystems, humans are the drivers of change [10, 11].

Studies from various regions of the world have traced human influences on lake ecosystems in the past, with landscape disturbance often representing an early signal from the paleolimnological record. The impacts of human activities on aquatic systems can vary widely over space and time, with evidence of human influence on inland water ecosystems worldwide dating back to pre-1850 CE (Common Era; for the last 2000-year period) based on various paleolimnological studies of lakes and wetlands at low latitudes. The impacts of human activities on lake ecosystems in the past was recorded including pollution, eutrophication, sedimentation, acidification, and salinization [10].

The study on the anthropogenic impacts on lake waters in Lake Funda, a deep crater lake located on Flores Island, part of the Azores Islands in the middle of the North Atlantic, has been conducted. The lake, which has not been affected by volcanic activity in the last 1000 years, provides a unique opportunity to investigate the effects of human activity and climate change on its condition. The evolution process of Lake Funda is divided into three distinct phases (as shown in Figure 2). The first phase (A), which lasted until 1335 CE, was driven primarily by climate and lake catchment processes. The second phase (B), between 1335 and 1560, was marked by a sudden change in the composition and diversity of diatoms and chironomids, indicating a shift in the trophic status of lake waters from mesotrophic to eutrophic conditions. This change was caused by a synergistic effect of high climate variability (Medieval Climate Anomaly) and human disturbances in the catchment, such as the introduction of livestock. In the last phase (1560 CE to present) (C), the lake has maintained a eutrophic condition, which is sustained through cycles and feedback between lake productivity and phosphorus remobilization in the lake. Climate variability and lake internal dynamics significantly influence lake ecosystems’ variability, such as phosphorus remobilization [12].

Figure 2.

The lake evolution process is divided into three main phases of conditions, namely (A) climate and lake catchment process; (B) changes in the trophic status of lake waters from mesotrophic to eutrophic; (C) the last phase with eutrophic state [12].

3. Sedimentation and siltation

Land use is one of the human interventions in nature that involves altering the condition of vegetation in the catchment area. Modifying natural vegetation can significantly contribute to the increase of erosion rate and drive the sedimentation pattern in the area. Sedimentation is closely related to erosion, influenced by various factors such as geological, topography, land slope, climate, soil type, and vegetation [13].

The study conducted on global-scale sediment flux patterns suggests that, with a few exceptions, land use impacts have a greater influence on sedimentation patterns than impact of climate change, particularly in smaller catchments (<10³ km²) [14]. The authors also observed that the intensity of land use has a qualitative impact on the sedimentation rate, although there are some caveats. In the case of the catchment of Lake Egari in Papua New Guinea, land clearing and the introduction of sweet potatoes in the nineteenth century resulted in a continued increase in sediment flux until the late twentieth century. This long-term sediment supply is expected to have an impact on the siltation of Lake Egari.

The lakes in the Pacific Northwest region of Canada have seen considerable disturbance in its catchment areas due to deforestation and road-building activities, particularly in recent decades. Therefore, the lake sedimentation rate in several cases has increased significantly along with these land use changes. However, the comparison data for other lakes did not show a significant effect of logging on sedimentation rates. Road construction activity had a particularly pronounced effect, with an average increase of 137% above the background rate and a maximum of up to 307%. Additionally, mining activities in the Lake Aldrich catchment between the early 1920s and 1954 also resulted in increased sedimentation rates during the period of land use disturbance [15].

Sedimentation has seriously threatened the Lake Tana Basin in Ethiopia, which can reduce its carrying capacity. The sedimentation is the impact of soil erosion due to agricultural activities in the catchment. Severe erosion in the Lake Tana Basin catchment is supported by inappropriate land use, especially on a high slope [16]. Similarly, Lake Malawi/Nyasa/Niassa, which is shared by Malawi, Tanzania, and Mozambique country and receives water from 13 rivers, is also impacted by sediment loads from agricultural activities and deforestation in its catchment area. The watersheds in the area are steep and narrow, with forested areas having lower sediment loads than those with extensive agricultural activities [17].

The high erosion as the impact of catchment damage has seriously threatened the sedimentation of Lake Rawa Pening. Lake Rawa Pening is a small (maximum area of 2667 ha) and shallow (the most profound part was 18 m) lake in Central Java, Indonesia. An analysis based on the Sediment Delivery Ratio Sub-Model indicated that the total sediment exports from the catchment reached 501628.6 tons/year. Sediment sources mainly come from the land with high slope and the land use was dominated by dry land agriculture and horticulture [18]. Another study on the evaluation of the impact of erosion on catchments was in Lake Tondano (the area was 4800 ha; catchment area: 31,400 ha) in North Sulawesi Indonesia, using bathymetry maps in 2015 and 2020. The results indicate a decrease in water depth from 2015 (maximum depth of 31.81 m and average depth of 12.88 m) to 2020 (maximum depth of 30.22 m and average depth of 12.66 m) at a rate of 4.4 cm y⁻¹, suggesting an increase of lake sedimentation to erosion in the catchment [19].

Siltation from catchment as an impact of land use activity allows fine sediments to be efficiently transferred from hillslopes to lake basins. Fine sediment is harmed to aquatic ecosystems [20]. A comprehensive document regarding the impact of suspended material in water has been published [21] entitled Effect of Suspended Sediment on Freshwater Fish and Fish Habitat as a collection of literature reviews. The document reveals the effect of suspended matter on eggs and larvae, physiological effects, aspects of foraging and fish growth, primary production and aquatic plants, invertebrates, and effects on the habitat, abundance, and community structure of fish. One of the effects of siltation was that it affected the attachment of Walleyes Sander vitreous fish eggs. One experiment found that rocks covered with fine sediment could not hold eggs, whereas the clean rocks could hold 35.9 + 36.6% of eggs [22].

4. Eutrophication

Eutrophication is an excessive enrichment process of water with mineral nutrients, primarily phosphorus (P), in freshwater lakes. Eutrophication is characterized by autotroph overproduction, mainly algae and cyanobacteria, which can lead to the depletion of dissolved oxygen in the water, especially in poorly mixed bottom water areas. High bacterial populations and high respiration rates contribute to the depletion of dissolved oxygen, resulting in conditions of hypoxia and anoxia. These conditions are often more pronounced in calm and dry conditions, particularly in warm waters. The relationship between P input, primary production, dissolved oxygen, and the trophic status of water clearly explained by [23].

Phosphorus (P) is a crucial nutrient for all life forms, and its availability can significantly impact primary production in aquatic ecosystems. Ecologists have identified P as the limiting factor for primary production in freshwater lakes, and input of P into waters must be managed to prevent eutrophication. However, noted that the limiting factors for primary production vary in different ecosystems, with nitrogen (N) being the limiting factor in oceans and P in lake waters [23]. Eutrophication occurs when the availability of limiting factors for photosynthesis, such as P and N, increases, leading to an overgrowth of algae [24].

Although naturally, eutrophication can take place in lake waters and is a result of the aging process of water so that lakes are described at the level of trophic status, namely oligotrophic (poor in nutrients), mesotrophic (moderate nutrient content), eutrophic (rich in nutrients) [9, 25]. However, the process of eutrophication that began in the mid-twentieth century is called cultural eutrophication, a major environmental problem in almost all lakes worldwide [26, 27, 28].

Land use and landscape modifications in the catchment area can indeed affect sediment behavior and nutrient supply to the waters area. Catchments are indeed the primary source of nutrients for lakes, and different transport capacities in each catchment can affect water quality in receiving waters. Nutrient loads supplied from catchment to lakes are influenced by various factors such as land use variety, geological, hydrological, nutrient availability, topographical factors, and response to rainfall [29]. To determine the trophic status of a lake, Total Nitrogen (TN) and Total Phosphorus (TP) are suggested as simple indicators [30]. Various criteria for trophic status have been established based on parameters such as TN, TP, chlorophyll, and Sechi depth [27, 31, 32, 33] (Table 1). However, eutrophication is a multidimensional natural event, so more than a single-factor evaluation is generally required [34]. To address of this a multidimensional approach to eutrophication classification proposed. Lakes are classified as oligotrophic, mesotrophic, and eutrophic with sub-classifications within each class based on the Trophic Status Index (TSI) of Total phosphorus (TP), chlorophyll (Chl-a), and Sechi Disc Depth (SDD) [35].

Trophic state	TN (mg/L)	TP (mg/L)	Chlorophyl-a (mg/m^3)	Sechi depth (m)	Reference
Oligotrophic	—	<0.011	<2.9	>5	[31]
	<0.3	<0.015	<3	>4	[32]
	<0.4	—	—	—	[33]
	<0.35	0.01	3.5	>4	[27]
Mesotrophic		0.011–0.0217	2.9–5.6	5–3	[31]
	0.3–0.65	0.015–0.025	3–7	2.5–4	[32]
	0.4–0.6		—		[33]
	0.35–0.65	0.01–0.03	3.5–9	2–4	[27]
Eutrophic		>0.0217	>5.6	<3	[31]
	>0.6	>0.025	>7	<2.5	[32]
	>0.65				[33]
	0.65–1.2	0.03–0.1	9–25	1–2	[27]
Hypertrophic	>1.200	>0.1	>25	<1	[27]

Table 1.

Criteria for the trophic status of lake waters based on a single parameter.

It is important to note that eutrophication caused by cultural factors is a major environmental issue in almost all lakes worldwide [26, 27, 28]. Therefore, managing land use and the transport of nutrients into the water area is crucial in preventing the negative impact of eutrophication.

Aquaculture activities in water bodies that use cages have a lot on the lakes and reservoirs in Indonesia, and have contributed as an additional input of phosphorus to the aquatic system, marking a significant cultural eutrophication phenomenon [36, 37, 38, 39]. From aquaculture activities in the cages system in Lake Maninjau, Indonesia, with a fish production of 36,219 tons, it is estimated that the phosphorus [P] load into the waters reach 387 tons y⁻¹, consisting of [P] as wasted through feces (130.5 tons y⁻¹) and wasted as dissolved (256.6 tons y⁻¹) [39]. Meanwhile, from cage aquaculture activities in Lake Toba on fish production rate 62,023 tons in 2016, the phosphorus load released into the waters was estimated at 570 tons (Table 2) [40]. The salmon (Oncorynchus mykiss; O. salar) culture activities in Lake Rupanco Chile, with the production of 1626 tons on August 2008 to July 2009, was estimated to supply TN and TP to the lake waters 76.4 tons y⁻¹- and 12.1tons y⁻¹, respectively, as unconsumed feed, feces, and urine [41].

Production of fish	(tons)^1	62,023.30
Estimated feed used	(tons)a	76,288.66
Content of P on feed	(tons)b	915.46
Retention of P by fish	(tons)c	345.13
Release of P from feces	(tons)d	192.25
Load of dissolved P in the form of metabolite residues	(tons)e	378.09
Total P release to the waters	(tons)	570.33

Table 2.

Prediction of phosphor loading from cage aquaculture activity in Lake Toba, Indonesia.

¹

Maritim Affairs and Fisheries Board, North Sumatra Province, Indonesia. Fisheries Annual Report 2015 (Unpublished).

^a

Food Conversion Ratio (FCR) of Nile tilapia = 1.23.

^b

1.2% of feed.

^c

37.7% from feed P content.

^d

21.0% from P content.

^e

41.3% from P content of feed based on Rismeyer (1988) formulation in [40].

Eutrophication is a well-known environmental stressor that impacts various ecosystem components, especially the phytoplankton community. The response to eutrophication can be observed at the individual, population, and community levels. At the individual level, physiologically, it can lead to increased mortality or rapid growth. Changes in species abundance or disappearance can be observed at the population level. At the community level, there are structural changes and alterations in biodiversity. At the ecosystem level, eutrophication can lead to the disruption of biochemical cycles and decreased productivity. These environmental stressors can increase in intensity and persistence over time, resulting in a greater impact on individual species and the ecosystem [42].

Based on various references, cyanobacteria have a positive response in line with the increase in phosphorus level. It is important to note that the response of one population level ultimately impacts the community level.

Generally, blooming cyanobacteria strongly characterize the eutrophication of freshwater ecosystems and ecologically has a negative effect, including decreasing water transparency and causing high oxygen fluctuations. Cyanobacteria blooms, on the other hand, produce toxins that are harmful to the surrounding and may have lethal effects on many aquatic or terrestrial organisms. The toxins produced by cyanobacteria include microcystins, anatoxin-a and saxitoxins. The existence of harmful cyanobacteria blooms is related to P load and N load [43, 44].

There are some toxic phytoplankton known as toxic harmful algae (HA) although in low assemblage proportion, other groups may occur harmful algal blooms (HABs) and almost on dominant composition in algal population. In fact, many HA types can grow abundantly and increase their toxin production when nutrient concentration is not in Redfieldian balance and when the inorganic nutrient components do not predominance [45].

Harmful algal blooms have become a national concern in the United States. Their appearance has become widespread globally in recent years, on the other hand, it was also recorded in every state and causes economic losses, affects human and animal health and disrupts the condition of the aquatic ecosystem itself. When cyanobacteria grow massively, die and decompose, much oxygen will be absorbed, producing an anoxic area where other organisms cannot live [46].

In a study conducted on 12 lakes in Kosciusko County, Indiana, microcystin concentrations ranged from 0.15 to 11 μg/L during blue-green algae blooms observed between 2015 and 2017. The highest mean microcystin concentrations were observed in Big Chapman Lake (1.64 μg/L) and the lowest in Big Barbee Lake (0.17 μg/L). According to the Indiana Department of Environmental Management (IDEM), microcystin concentrations above 4 μg/L and blue-green algae abundance above 20,000 cells/L pose a risk to human health. Therefore, monitoring and managing blue-green algae blooms and their associated toxins are crucial to mitigate potential impacts on both human health and the aquatic ecosystem [47].

One eutrophication phenomenon that has received little attention is the abundance of attached filamentous algae (FABs; filamentous algal blooms) in clear lakes worldwide, which mainly grow and blooms in the littoral area of the lake. These attached algal communities generally consist of groups of green algae and/or cyanobacteria, a form of lake degradation without indicating eutrophic waters. They cannot be explained in current eutrophication models. This phenomenon is allegedly due to the pollution of groundwater nutrients. Nutrient concentrations in groundwater higher than those in the water column are thought to be a driving force for the development of FABs. In contrast, phytoplankton growth in the water column is limited [48].

The blooms of FABs in the littoral zone must be considered because it is an essential area with high biodiversity. Based on observations in Bear Lake in the USA, a large and, clear lake, Cladophora glomerata dominates the FABs groups [49]. Cladophora glomerata indicates a eutrophic aquatic flora in Windermere, English Lake District, during observations from 1992 to 1993. In the southern basin of the lake, the maximum biomass of C. glomerata is almost 200 g dry weight m⁻², up to six times the biomass in the northern basin. Observations on phosphate concentration in the southern part of the lake on average was 0.12 g P m⁻² was higher than in the northern area was 0.01 g P m⁻², meanwhile, the standing stock of N in the South Basin was 1.81 g N m⁻², elevenfold that in the North Basin at 0.16 g N m⁻², on average [50].

The high biomass but low productivity of FABs can have severe consequences for lake ecosystems. The existence of periphyton assemblages, where FABs are absent, although low biomass but high productivity provide important value as food webs in lakes. The cause of the FABs phenomenon in lake waters worldwide is difficult to ascertain, mainly when various pressures occur simultaneously in a lake ecosystem. For instance, in the case discussed above, factors such as climate change, anthropogenic eutrophication, and invasive species could all contribute to the blooming of FABs [49].

The impact of eutrophication on floodplain lakes causes water conditions to change from clear to turbid and a decrease in macrophyte coverage. The decrease of macrophytes assemblages along the eutrophication gradient resulting in changes in taxonomic groups and the diversity of macrobenthic communities. These changes are attributed to the different tolerance levels of macroinvertebrate taxonomic groups to trophic states, which generally lead to decreased taxa. An increase in the abundance of phytoplankton in response to eutrophication was followed by a decrease in the euphotic depth, which inhibited macrophytes growth and impacted the number of macroinvertebrate species. Meanwhile, the response of the macroinvertebrate community to eutrophication showed a pattern of density and total macroinvertebrate biomass, where collectors-gatherers (mainly Tubificidae and Chironomidae) and predators (e.g., Tanypus) increased, scrapers (e.g., Bithyniidae) decreased, and decreased again (Figure 3). Macrophytes play an essential role in maintaining the integrity of macroinvertebrate diversity, as they serve as the primary source and habitat for epiphytic animals [51].

Figure 3.

Trend response macroinvertebrate groups based on functional feeding groups to eutrophication [51].

5. Organic loading

Many organic loads due to anthropogenic activities as allochthonous material have entered lake waters and impacted the water column and the sediment zone conditions. Organic load and other substances that are deposited into the water column in the bottom waters act as energy for bacteria, and throughout the process, will go through remineralization processes, respiration, oxidation of metabolites and consume much oxygen, causing a decrease in oxygen dissolved in the region [52, 53]. In the hypolimnetic column, various aerobic microbes mineralize the organic matter. Oxygen depletion is also accelerated in the hypolimnion region due to anaerobic processes, such as methane and ammonium [54, 55].

The supply of organic matter is often ignored in the environmental monitoring of lake waters. The crisis of anoxic conditions in almost all hypolimnion areas is also faced in tropical lakes, with rates of hypolimnion decline reaching 0.046–5.9 m²y⁻¹. This is the impact of organic loads and climate change which not allows vertical mixing and oxygen-deficient water change [56].

Cage aquaculture activities in Lake Toba Indonesia contribute to the reduction of the oxic hypolimnion layer, marked by the anoxic column in the cage area (CA) being much narrower than in the non-cage area (NCA) and dissolved oxygen availability in water the column that is suitable for animal life in CA was shallower than NCA (Figure 4) [57].

Figure 4.

Dissolved oxygen vertical stratification pattern in non-cage aquaculture (NCA) and in cage aquaculture (CA) area [57].

The tolerance values of certain macroinvertebrate groups, i,e anthropod family have been classified in a family-level biotic index (FBI) as a rapid field assessment tool of organic pollution in the lotic systems. There is a relationship between FBI, water quality and the degree of organic pollution [58, 59]. Nevertheless, a biological index based on macroinvertebrates communities related to their response to environmental stressors is not easy to apply in the lake, due to the stagnant condition, and there is a diffusion factor in the lentic ecosystem. The macroinvertebrate community structure appears to be more permanent and requires high identification until species level [60].

One postulate generally accepted that macroinvertebrates assemblages in lake benthic habitats are driven by various and integrated environmental factors including temperature, oxygen, and organic matter availability [61]. The sensitivity to organic load has formed certain of macroinvertebrates’ community clusters and responses by changing their community structure. The term eutrophication is related to community of macroinvertebrates which refer to sediment conditions that show undergoing organic enrichment and are characterized by a decrease of oxygen.

The increase of organic sediment loading and other important chemical variable indicates that eutrophication can be assessed using bio indicators such as Tubificid and lumbriculid species [62]. The occurrence of lumbriculid and tubificid species is associated to the eutrophic state of the aquatic ecosystem, which assumes that organic sediment loading originates from phytoplankton production as the dominant autochthonous source. It was demonstrated in Lake Geneva, Switzerland, which sorted sediment organic loading condition based on the black layer thickness (represent organic) of sediment upper part was <10 cm (LOS; Organic sediment was low) and on black layers thickness > 10 cm (HOS; Organic sediment was high) and how the effect to macroinvertebrate community. Show that the mean abundance of oligotrophic worm species in the LOS area reached 30%, while in the HOS area, it was below 15% [63].

In observing the effect of organic pollution which validated as high-level ammonia and orthophosphate and low oxygen in Lake Lysimachia (Western Greece) showed that Limnodrilus hoffmeisteri in particular and species of chironomids (Paratrichocladius rufiventris, and adults of Cricotopus bicinctus dan Rheocricotopus atripes) characterized as polluted community. Three species that characterize clean water condition and high oxygen, namely Psammoryctides barbatus, Dianella thiesseana, and Gammarus sp. [60].

Organic material sourced from anthropogenic activities, includes metal and total phosphorus, exerts pressure on the lake sediment area. Based on a multivariate comparison of environment chemical variables and bio indicators species obtained six groups which characterized one level of pollution and trophic status of the sediment. The groups are as follows: (1) polluted and eutrophic (Potamothrix hammoniensis, Peloscolex ferox, Limnodrilus claparedeanus); (2) polluted and mesotrophic (Psammoryctides barbatus); (3) unpolluted and mesotrophic (Limnodrilus hoffmeisteri, Limnodrilus udekemianus); (4) polluted and oligomesotrophic (Potamothrix vejdovskyi); and (5) unpolluted and oligotrophic (Stylodrilus lemani, Peloscolex velutinus) [64].

Eutrophication conditions of Lake Yamanakako, one of five lakes in Fuji including lakes Kawaguchiko, Motosuko, Saiko, Shojiko, and Yamanakako in Japan, have changed the distribution of chironomid fauna density between 1994 and 2003. Chironomus nipponensis larvae decreased while Propsilocerus akamusi increased, and at the same time, the density of Tanypodia larvae had decreased. In this study, the density of P. akamusi larva showed a positive correlation to sediment’s organic ignition loss (IL) value [65]. This show that the eutrophication of Lake Tamanakako is characterized by organic enrichment in the sediment. The decrease of Tanypodia abundance can occur due to low oxygen, as well known, Tanypodia can not adapt to low oxygen.

6. Acidification

Acidification is a process that leads to a decrease in pH in water bodies, and it can occur at both local and global scales. Local-scale acidification is often linked to soil conditions in a catchment area. On a global scale, acidification is caused by “acid rain,” which results from burning fossil fuels and has a transboundary impact. On a local scale, lake acidification is the impact of catchment soil condition. Before the period of acid rain, acidification in lakes was related to changes in catchment conditions rather than acid deposition. Lake in Galloway, Scotland, undergoing acidification (pH 5.5–6.0) before peat formation based on lake acidity data from the earlier post-glacial period. However, acidification of lakes due to acid rain began to occur after AD 1850 when acid emissions increased due to the burning of fossil fuels. It is worth noting that acidification resulting from soil acidification differs from the current acidification phenomenon, which has been widely reported in Europe and North America [66].

In the 1970–1980s, acidification of lake waters caused by atmospheric sulfur deposits became a significant international concern, leading to the implementation of strong sulfur control programs in Europe and North America. However, various factors prevented their widespread adoption. While reducing industrial sector employment, the environmental impact of sulfur control programs remained unclear. Interestingly, it was discovered that nitrogen deposition is a significant contributor to lake acidification in some regions [67].

Ammonia, mainly produced from livestock, fertilizer, and industrial activities, enters the atmosphere, and neutralizes sulfuric acid with nitrogen oxides, substantially increasing pH precipitation. When ammonium compounds enter the soil and water environment, they can be oxidized to nitric acid, releasing acid [68]. Acid deposits may contain high concentrations of NO₃ and NH₄. In the Irish Lakes, for example, precipitation from ten sampling stations during 1995–1996 had a nitrogen concentration 1.8 times that of SO₄²⁺, with NH₄⁺ concentration twice that of NO₃⁻ [69].

Based on experiments on lake acidification (from pH 6.2 to 4.7) in Little Rock Lake (Wisconsin, USA) on the species richness and annual biomass on five tropic levels of biota (phytoplankton, herbivores, omnivore, carnivorous zooplankton, and fish) indicates an impact of this acidification. There was a marked decrease in the relative richness of fish and zooplankton compared to phytoplankton, in which the phytoplankton did not appear to be affected by acidification [70].

Acidification has an impact on macroinvertebrates community and is observed in Pennsylvania lakes; Deep (Area [A]; 3.0 ha; Maximum depth [D_max]: 6.8 m), Lacawac (A: 21.0 ha; D_max: 13.5 m), and Long Pond (A; 32.8 ha; D_max: 7.0 m). The lakes showed very significant differences in acidification levels. Deep was acidified (mean total alkalinity <0.0 μeq L⁻¹; the mean pH decreased from 5.5 to 4.2 between 1981 and 1983), Lacawac was moderately sensitive to acidification (mean total alkalinity: 47 μeq L⁻¹; the mean pH 6.1) and Long Pond was the least sensitive to acidification (mean total alkalinity 190 μeq L⁻¹; mean pH 6.6). The macroinvertebrate community formed on three levels of acidification show that in acid lakes dominated by Chironomidae (71.3% in number; 19.6% in wet weight), the abundance in the number of Chironomidae was dominant (43%) in moderate acidification lakes but in biomass (wet weight) dominated by Odonata (18.6%) and Mollusk (12.7%), in the least sensitive lake show that the Amphipoda (31.3%) and Chironomidae was dominant in number but in biomass (wet weight) Mollusca makes up 55.1% of total in the least sensitive lake individual abundance is dominated by Amphipoda (31.3%) and Chironomidae (27.3%) while from Mollusca biomass it makes up 55.1% of the total [71].

7. Habitat modification

Lake ecosystem habitats are uniquely characterized by paired patterns that play a crucial role in shaping nutrient cycles, predator-prey interactions, food web structure, and ecosystem stability, creating an integrated system. Habitat modification, such as anthropogenic pressures, can significantly alter the interdependence between habitats, disrupting the crucial flow of energy and nutrients in the lake ecosystem [72]. Habitat modification, including shoreline morphology and water level changes, can impact the littoral habitat area in the lake ecosystem.

The physical condition of the shore zone of the lakes can be altered, and various activities, such as recreation and development, can lead to disturbance in the riparian and littoral zone. The shore zone plays a crucial role in maintaining the biodiversity of lake ecosystems due to its complex habitats, unique plant and animal communities, and high biochemical activity. It also contributes significantly to ecological processes and structures in aquatic ecosystems. Alterations to the morphology of the shoreline and riparian habitats can significantly impact all processes within the lake ecosystem [73].

The littoral zone is an essential lake ecosystem zone supporting the highest productivity. The littoral zone and benthic habitat of the lake waters form a microhabitat for macroinvertebrate communities, providing a feeding and breeding ground for and shelter from predators and wave action [9, 74].

Various human activities can cause modification of littoral areas and lead to severe impacts on benthic habitats. These activities include forest logging in catchment areas and riparian zones, removal of debris from lake shores, macrophyte removal, wetland drainage, dredging, and water lake management. The complexity of the littoral habitat is disrupted due to these activities, and the ecological damage caused by changes in the morphology of the shore zone is much higher than that caused by eutrophication [75]. The damage caused to riparian vegetation results in a decrease in the supply of organic matter from the land to the littoral food web system, indicating the decoupling of the littoral from the riparian zone [76].

Changes in lake hydrology, particularly those resulting in water level fluctuations beyond natural limits for the purposes of hydropower, flood control, and aquatic plant management, pose a threat to the ecological integrity of the shore zone. While water level fluctuations are a common pattern in lake ecosystems, changes in hydrology beyond natural variability can harm lake ecosystems [73]. The Miorina Dam, located in Italy and Switzerland, regulates water level fluctuations in Lake Maggiore. However, this has led to significant changes in the ecology of the littoral zone, impacting the structure and function of benthic copepod groups, including the abundance of ovigerous females, opportunists, omnivores, and deposit feeders. While no missing classes were observed, variations in the composition and function of taxonomic groups can have significant implications for entire communities [77]. Water level fluctuation due to lake discharge regulation for hydroelectric power plants is expected impact the wetland area. The semi aquatic area on lake the shore zone is considered as eel (Anguilla spp.) habitat so in the long term will affect the eel population [78].

The hydrological balance of Lake Bracciano, the largest and deepest lake in Italy, has been disturbed due to the withdrawal of water for human needs beyond its potential, which is exacerbated by climate change and decreased rainfall. This has reduced the richness and taxonomic abundance of the invertebrate assemblage of sessile forms such as water mites, gastropods, nematodes, and naidid oligochaetes that feed on living plants and epiphytic algae, and an increase in the types of mobile detritus eaters. Lowering the water level of Lake Bracciano has led to the removal of littoral habitats, especially in areas where the bottom slopes less steeply, and the distribution of macrophytes is less frequent when the annual water level is low [79].

8. Conclusion

As the human population grows and their needs and interests become more diverse, lake conditions will likely change. The most significant impact of human activity on the ecosystem is sedimentation and habitat modification which alters the biota’s habitat and physiology. Nutrient enrichment from the phosphorous loading into the water overproduces the algae and cyanobacteria, decreasing water transparency and inducing high oxygen fluctuation. High organic matter load into the water causes oxygen depletion, however, the supply of organic matter is often ignored in the environmental monitoring of lake waters. Acidification which occurs at local and global scales affects the biota community. Therefore, it is crucial to increase our knowledge and understanding of the aquatic environment, especially lakes, so that we can develop a greater appreciation for and respect towards nature.

Acknowledgments

The authors thank the Research Center for Conservation of Marine and Inland Water Resources and Research Center for Limnology and Water Resources at the National Research and Innovation Agency (BRIN), Indonesia for their support. We also would like to thank our colleagues in BRIN for constructive discussion.