Effect of climate change on “Eichhornia crassipes” infestation in Lake Tana Sub-Basin, North Western Ethiopia

ABSTRACT

Climate change-induced alteration of ecosystem conditions can enable the spread of invasive plant species through both range expansion and the creation of habitats and conditions suitable for newly introduced exotic species. This research tries to evaluate the effect of climate change on ‘Eichhornia crassipes’ intensification in Lake Tana Sub-Basin, North Western Ethiopia. Land use land cover change was analyzed using ArcGIS 10.8 and temperature and rainfall data were interpolated to evaluate the effect of climate change on water hyacinth infestation. The result of the study shows that the area covered by water was decreased, whereas the area covered by water hyacinth was increased by 9.3%. The highest decrease −82.41% in land cover was recorded for savanna forest land which was found in the surrounding area of the lake. A significant amount of water bodies was also converted to wetlands due to the invasion of water hyacinths. The result also shows that areas with high annual temperature readings result in a high rate of water hyacinth invasion. The study also suggests that areas that receive high rainfall were characterized by having a high invasion of water hyacinth. From the study, it is possible to conclude that climate change facilitates the invasion of water hyacinths in Lake Tana. Comprehensive management strategies need to be developed by the government, policymakers, and environmentalists especially considering the positive use of water hyacinth.

KEYWORDS:

• Climate change
• invasive species
• land use
• water hyacinth

1. Introduction

Diverse invasive plant species are being impacted by climate change (Diez et al., 2012). Since rising temperatures and warmer winters improve the likelihood of successful invasion growth and reproduction as well as higher transmission rates of water hyacinth, many invasive plants, including water hyacinth, may benefit from climate change (Bellard et al., 2014). According to Dukes and Mooney (1999), the indirect effects of climate change on water hyacinth are very considerable. For instance, warmer, shorter winters in lower temperate regions will stress host species, making them more susceptible to invasion (Pysˇek et al., 2008). Although some of these modifications may be advantageous, such as when a biocontrol agent targets a weed, the overall impact may be negative due to drought and increased atmospheric carbon dioxide levels (Piao et al., 2019). Climate change has resulted in changing rainfall patterns, drying of local springs and streams, and alterations in water hyacinth distribution, phenology, and morphology (Keith et al., 2008). Additionally, there has been a shift in the agriculture calendar, increased invasion of exotic plant species, and the emergence of diseases and pests (IPCC, 2014). The warming temperatures and changes in CO₂ concentrations that lead to climate change are likely to increase opportunities for invasion of water hyacinth due to their adaptability to disturbance and a broader range of environmental conditions and controls (Thomas et al., 2008). Furthermore, invasive plant species can move along previously inaccessible pathways of spread in both natural and artificial environments facilitated by warmer temperatures (Katharina Engel & J, 2011) since they have a wider range of tolerance.

The interplay between climate change and the spread of water hyacinth is expected to increase the vulnerability of aquatic environment to degradation (Wiens et al., 2019). Aquatic ecosystems and invasive plant species will be significantly affected by increased CO₂, rising temperatures, changing precipitation patterns, and more frequent occurrences of extreme events such as fire and flooding (Bertrand et al., 2011). Among these variables, water is expected to play a crucial role in facilitating invasion, mainly by weakening the resistance of agricultural and native ecosystems (Masters and Norgrove, 2010).

The current rate and magnitude of climate change are projected to exceed the survival and adaptation abilities of several species, resulting in increased extinction rates (Carroll et al., 2017). Ecologically speaking, climate velocity refers to the speed and trajectory that a species must move to maintain its existing climate conditions under climate change (Molinos et al., 2019). This scenario is especially relevant in Africa, where ongoing threats such as habitat destruction, land use change, and population growth interact nonlinearly with climate change, resulting in higher-than-anticipated negative impacts (Barlow et al., 2018).

The management of invasive plant species is further complicated by climate change, as warming temperatures, changing humidity, and fluctuating precipitation are causing shifts in the ranges of various species (Thomas et al., 2008). This shift is expected to expose certain regions to new invasion vectors and pathways, facilitating the expansion of some species into areas where they previously could not survive or reproduce (Dai et al., 2022). This will result in an unprecedented influx of new invaders and range expansions of established ones (Thomas et al., 2008). However, it remains uncertain which species, regions, and ecosystem services are most at risk due to the intensification of invasive plant species facilitated by climate change (Dai et al., 2022). On the other hand, modeling how climate change will affect invasive species provides a unique opportunity to identify and prevent range-shifting species from becoming widespread and problematic. The study mainly focuses on temperature and rainfall fluctuation which are two most climate change indicators. This research tries to provide new insight for developing invasive species management with the current and future fragile climate variables due to the resistance of the weed to the existing physical removal control method. The research was also significant to implement sustainable lake utilization and management to adapt climate change. Additionally, the research contributes a lot for achieving sustainable development goals 13 (mitigation of climate change impact). This research tries to evaluate the effect of climate change on the infestation of water hyacinths at the Lake Tana sub-basin.

2. Description of study area

The research site is situated in the Amhara National Regional State, specifically in the Lake Tana Sub-basin (LTSB) of the Blue Nile Basin (Figure 1). The Blue Nile Basin is recognized as the largest river basin in Ethiopia and comprises the LTSB, home to the world’s largest freshwater and oligotrophic-high altitude lake, Lake Tana (CSA, 2012). The area cover a total land area of 1,589,654.98 hectares in the upper reaches of the Blue Nile River (CSA, 2012). The atmospheric temperature at Lake Tana sub-basin typically falls between 13 and 22 °C, with a decrease of 0.7 °C per 100 m in elevation (Goshu & Aynalem, 2017). Located geographically in the range of 10°45054.1” N, 36°10024.9” E and 12°50015.9” N, 38°50054.48” E (Dersseh et al., 2019), Lake Tana experiences an average annual rainfall of 1248 mm per year (mm yr − 1). This represents a 7% reduction in rainfall when compared to the surrounding watershed.

Figure 1. Map of the study area.

The Lake Tana basin is mainly characterized by cultivable land, which accounts for 71% of the area, followed by grazing land (9%), infrastructure (6%), forestland (3%), and other types of land. The major land cover types include farmland, water bodies, wetlands, forests, woodlands, shrubs, rangeland, grassland, and settlements. The dominant soil types on Lake Tana’s islands, peninsulas, wetlands, and upland areas are Nitosols, Luvisols, and Vertisols (Goshu & Aynalem, 2017).

3. Method

3.1. Data sates

To address the research question, both satellite imagery and meteorological data were utilized. The satellite imagery was obtained via download from Google Earth Engine, while the meteorological data was acquired from the NASA climatic database. To access the meteorological data, five meteorological stations located in the study area were used. These data sets were calibrated to validate the accuracy of the NASA climatic database. Rainfall and temperature data were collected for 27 sample points based on the nearby metrological station. This data was used to interpolate with the area extent change for that land use land cover change in water hyacinth covered area in the study area. This temperature and rainfall data were used to relate invasion of water hyacinth since growth, survival and establishment of the weed was strongly dependent on temperature and rainfall.

3.2. Satellite images

Several satellite image data sets were used to explore how climate change may affect the distribution of an invasive species, notably the Water Hyacinth. Landsat Thematic Mapper (TM) from 1986, Enhanced Thematic Mapper Plus (ETM+) from 2011, 2015, and 2020, and Multispectral Scanner (MSS) from 1972 comprised the satellite imagery. For Landsat TM and ETM+ photos, all images were taken for scenes with a worldwide reference system (WRS2) path of 170 and row 053. The scene with WRS1 path 182 and row 053 was recorded for the Landsat MSS image, completely enclosing the research region. The satellite images were downloaded from USGS and purchased from the Ethiopian Map Agencies (EMA).

In this study, the dry season was determined to be the optimal period for detecting the impact of climate change on the distribution of the invasive species Water Hyacinth. This is due to the difficulty in analyzing satellite images taken during the rainy season, particularly from June to December according to the Ethiopian calendar. Thus, satellite images were obtained for the months of January to April over a span of three consecutive years with five-year intervals. GIS and remote sensing methods were utilized to relate climatic variables, such as temperature and rainfall fluctuations, to assess their influence on the extent of water hyacinth coverage in the lake and surrounding terrestrial land use.

In this study, a high-resolution satellite image from Planet Constellation was employed to ascertain the spatial and temporal distributions of the invasive species within the study area. Utilizing a finer resolution than RapidEye, PlanetScope was utilized to map the spatial distribution of the invasive species coverage. PlanetScope has a daily revisit rate with a spatial resolution of 3–5 m in the visible (455–515 nm, 500–590 nm, and 590–670 nm) and near-infrared (780–860 nm) spectrum (Altena et al., 2017). The PlanetScope satellite image encompassing the study area was obtained on 9 January 2021, with 12 cloud-free images collected between January 2020 and April 2021, with particular focus given to areas where invasive species infestation is extensive. Geometrically corrected images were obtained through the use of highly accurate distributed ground control points provided by PlanetScope (Thi et al., 2019).

3.3. Metrological data

From NASA’s most recent 30-year record, two bioclimatic variables were taken out in order to represent the current climate conditions of the research area (Fick & Robert, 2017). These variables included a variety of climatic factors, including monthly extremes for temperature and precipitation in the study area as well as annual averages, seasonality metrics, and monthly extremes.

3.4. Image pre processing

In this study, a supervised classification technique was utilized to classify time-series images collected from satellite imagery. The classified images for each month were then processed in both the spatial analyst tool and conversion tools (from raster to polygon) of ArcGIS 10.8 software to calculate water hyacinth-covered areas within the Google Earth Engine platform. The estimated values were further analyzed using descriptive and analytical statistical tools. Additionally, relevant bands were analyzed in both ERDAS IMAGENE2015 and Arc GIS 10.8 software after geo-referencing Landsat images.

To account for any geometric and radiometric distortion that may occur from remote-sensing technology, such as earth rotation, platform instability, and atmospheric effects, image preprocessing was necessary (Teshome Abate Beza, 2011). Geometric correction, georeferencing, and image enhancement were applied as standard preprocessing techniques (ERDAS, 1999). This study utilized ENVI 4.3 software to conduct preprocessing techniques, including projection of Landsat images to UTM 37 north and WGS84 and clipping the projected image with the study area boundary shape file. Image enhancement was also conducted in line with (Coppin et al., 1996)method to improve visibility and interpretability of each image.

3.5. Extent and rate of changes

Analysis of the aerial extent and spatial distribution of land characteristics between two eras is the process of change detection (Mallupattu et al., 2013). Due to the well-known proliferation of invasive species throughout these years, this study conducted change detection over two time periods, specifically from 2011 to 2015 and from 2016 to 2021 with five-year intervals. Using land use and land cover maps from the two distinct periods, the land change module tab in ArcGIS software was used to examine changes in terms of gain, loss, net change, and net contribution. Net contribution information provides a complete understanding of land-use and land-cover dynamics, including which classes changed and by how much. Transitions detection was also performed for two time periods. Finally, this study solely conducted a net contribution analysis for the invasive species (water hyacinth), as it is the main focus of the research.

While the LULC statistics was calculated in various ways, the variations in LULC in the three periods were determined by the difference in the values of 2011, 2015, and 2021 of the same category (Gashaw et al., 2018), which are shown in Equations below

Total gain, loss = Area of final year − Area of initial year,

$\mathrm{Percentage}\mathrm{LULC}\mathrm{Change}=\frac{\mathrm{Area}\mathrm{final}\mathrm{year}-\mathrm{Area}\mathrm{initial}\mathrm{year}}{\mathrm{Area}\mathrm{initial}\mathrm{year}}\times 100$

$\mathrm{LUI}=\frac{\mathrm{Ub}-\mathrm{Ua}}{\mathrm{Ua}}\times \frac{1}{\mathrm{T}}\times 100$

where LUI = the annual rate of change in area for the land use classes. Ua = area of land use class at time a, Ub = area of land use class at time b, and T = length of time in the year between a and b. If LUI < 0, the land cover type is in a state of depletion. The larger the absolute value of LUI indicates, the more intensively land has been depleted. LUI ≥ 0 means just the opposite (the land cover type in a state of expansion) (Yirsaw et al., 2016).

To prepare the selected satellite images for analysis, raw data was converted to reflectance using provided coefficients. A maximum likelihood supervised classification method was utilized to classify the preprocessed satellite image. This study found the maximum likelihood classification algorithm to be highly suitable due to the low correlation between the bands used in classification, resulting in a stable inverse matrix of the variance-covariance matrix. Training samples representative of the study area were collected for individual images to facilitate supervised classification. Validation of the supervised classification will take place on 25 April 2022, using invasive species coverage tracked via boat and handheld GPS. Following validation, the same supervised classification approach will be applied to the selected images.

3.6. Data Analyses

The study utilized MS Excel’s descriptive statistics feature to analyze data related to rainfall, humidity, and temperature. ERDAS Imagine 2015, ENVI 4.7, ArcGIS 10.8, and Global Mapper 11 were employed for all image processing and analysis. To examine the correlation between climatic variables and invasive species coverage, interpolation techniques in ArcGIS 10.8 were used to overlay the trend of climatic variables with the area coverage of invasive species. The study also analyzed the impact of climate change on increasing the area coverage of invasive species via interpolation techniques by examining the relationship between area coverage of each invasive species and climate change.

4. Result and discussion

4.1. Extent of water hyacinth invasion on the surface of Lake Tana

This study examined changes in land use and land cover for 3 years (2011, 2015, and 2021) using three-generation Landsat time-series data. Six different classes were considered: cropland, water hyacinth vegetation, bare land, built-up areas, water, and wetlands. The resulting LULC maps for each year were classified and displayed in Figure 2 to illustrate the spatial distribution of the various land use and land cover types.

Figure 2. Land use land cover map of Lake Tana and surrounding areas.

The study’s findings indicate an upward trend in the area covered by water hyacinth within the study area over time. Specifically, there was a 9.3% increase in the invasive weed’s coverage area from 13.26 km² in 2011 to 14.5 km² in later years (Table 1). Conversely, the savanna forest, which typically safeguards the lake entrance against muddy runoff, experienced a significant reduction in coverage, decreasing at a rate of −82.41%. Additionally, the area covered by water in the study area decreased annually by 0.35% (Table 1). The permanent wetland area was increased by 45.05%, resulting in a gradual decrease in the water body’s size (Table 1).

Table 1. Shift in land use land cover in terms of area in (km2)

Land use/land cover type	Area(km^2) in 2011	Area(km^2) in 2021	Rate of change (%)
Savanna	0.78	0.14	−82.41
Water hyacinth	13.26	14.50	9.30
Wetland	77.35	112.20	45.05
Cropland	0.56	0.35	−37.87
Urban buildup land	0.21	0.21	0.00
Bare land	43.72	16.89	−61.36
Water body	2935.68	2925.49	−0.35

The findings presented in Table 1 demonstrate substantial changes in land use and cover between 2011 and 2021. Specifically, the coverage area of small-scale farmlands (cropland) decreased significantly by −37.87%. This reduction in cropland coverage also drove changes in other areas surrounding the lake. For instance, the proportionate area of bare land expanded by −61.36% during the same period (Table 1).

Table 1 and Figure 3 illustrate that the rate of change in coverage area has decreased for savanna forests (−82.42%), cropland (−37.87%), bare land (−61.36%), and water bodies (−0.35%). Conversely, the rate of change in coverage area has increased for water hyacinth (9.3%) and wetlands (45.05%).

Figure 3. Rate of land use land cover change at Lake Tana and surrounding areas.

Figure 3 highlights that the most significant change in the coverage area of the lake has been due to the spread of water hyacinth. Specifically, water hyacinth appears to have taken over water bodies, bare land, and croplands in the study area. It is worth noting that the bare land coverage area could have already been degraded or exhibited low levels of vegetation before water hyacinth invaded. Therefore, our findings provide evidence that the invasion of water hyacinth is a critical factor driving changes in land use and land cover, leading to losses of ecosystem services in the study area (Figure 4).

Figure 4. Land use land cover dynamics at Lake Tana and surrounding areas.

Figure 4 reveals that water hyacinth is surrounding the lake, with its coverage area increasing over time. The figure also provides insight into how the invasion of water hyacinth has contributed to a decrease in water content on the lake’s surface. Additionally, Figure 5 classifies six primary land use and cover types based on their respective coverage areas and rates of change over time.

Figure 5. Water hyacinth invaded area on the study area.

4.2. Effect of climate change on invasion of water hyacinth over the lake surface

In line with our research, temperature changes were significantly connected with the invasion of water hyacinth. Figure 6 show that areas of the lake that experienced high temperatures also experienced high levels of water hyacinth infestation. As a result, compared to the lake’s center, sections around the lake’s edge, which frequently had higher surface temperatures, had more water hyacinth invasion.

Figure 6. Effect of temperature fluctuation on water hyacinth invasion.

Further evidence from the interpolated image points to a tendency for water hyacinth invasion rates to reduce as lake depth rises (Figure 6). A significant incidence of water hyacinth invasion was correlated with greater surface temperatures in the eastern and western parts of the lake, specifically. The northern and southern portions of the Lake Shore, where water hyacinth was somewhat abundant, also displayed a correlation with rising temperatures (Figure 6).

By interpolating the annual rainfall trend, our analysis demonstrated a strong correlation between rainfall fluctuations and water hyacinth invasion (Figure 7). Specifically, regions with high levels of rainfall in the lake had correspondingly high occurrences of water hyacinth infestations. Given that the lake’s shoreline tends to receive more annual rainfall, it is not surprising that this area sees a higher degree of water hyacinth invasion compared to the central part of the lake, which receives less rainfall and therefore experiences less water hyacinth invasion.

According to our analysis, which required extrapolating the results of the annual rainfall trend, the rate of water hyacinth invasion tends to decline as lake depth rises, which is consistent with a decline in rainfall amounts (Figure 7). Water hyacinth invasion rates on the lake’s surface were significantly greater in the eastern and western parts of the lake, which receive more annual rainfall. The Lake Shore’s northern and southern regions, which are strongly correlated with variations in yearly rainfall, likewise showed substantial water hyacinth coverage (Figure 7).

Figure 7. Effect of rainfall fluctuation on water hyacinth infestation.

4.3. Discussion

Our study indicates a significant increase in water hyacinth-invaded areas and wetlands, accompanied by a decrease in communal grazing lands, woodlands, croplands, and bare land. The study shows that the savanna or wood land was decreased due to excessive clearance of tree, shrub and herb species for fuel wood and construction materials by local communities. Some savanna species were unable to resist the flooding effect which removes the species from the lakeshore areas. This reduction in area coverage was found to be highly associated with the invasion of water hyacinth, which competes for water resources with other plant species, leading to a decline in water body coverage. The decrease in water body of the lake due to increase in water hyacinth invasion affects fish production since it can minimize the suitability of the habitat for fish reproduction and growth. Invasion of water hyacinth also decreases the food availability for fish. Agricultural and bare lands were particularly affected over time as they became overrun by invasive weeds. Our findings are consistent with those of other studies, including (Sarah et al., 2016).

The analysis of land use and land cover change in the study area has revealed a concerning situation, with significant losses in the indigenous water body and savanna, as well as a decline in cropland. These changes are driven by several factors, including agricultural practices, climate change, invasive species, population growth, and poverty (Katusiime et al., 2023). Moreover, the area covered by water in the lake has been decreasing due to the invasion of water hyacinths, which quickly uptake water and contribute to the reduction of the water body. These findings are consistent with those of (Soeprobowati et al., 2021), who observed a decrease in water body area in Galela Lake, followed by an increase in the riparian zone from 71.28 ha in 2002 (0.92% of the total area) to 81.54 ha (1.05%) in 2015 and 92.34 ha (1.19%) in 2019.

Climate change impacts the growth, reproduction, and distribution of plant species and is likely to be contingent upon their life history characteristics. For instance, annual and biennial plant species with shorter generation times may have greater opportunities to establish new genotypes that can adapt more readily to changing environmental conditions compared to perennial species (Copeland et al., 2018). Reproduction in clonal plant species may be less affected by harsh climates than non-clonal species since they can bypass temperature-regulated flower and fruit production and propagate asexually (Ye et al., 2014). Clonal plants possess unique traits that enable them to naturalize quickly in challenging environments (Negreiros et al., 2014). The reproductive system of water hyacinth facilitated its easy adaptation to changes caused by climate change and enabled it to invade Lake Tana. Our findings are consistent with those of (Lodaya et al., 2022), who reported that Thrips parvispinus (Karny) was infesting chili crops grown in middle Gujarat due to climate change.

The Northern, Eastern, and Western parts of Lake Tana provide suitable habitats for water hyacinth due to the availability of tributary rivers such as River Megch, River Ribe, and River Gumara, which are major contributors to the lake (Siddiqui et al., 2021). Invasions of water hyacinth are prevalent in these areas due to high nutrient flow from the surrounding watersheds, which is often related to high rainfall and temperature. The high nutrient load during summer season from the surrounding area provide high nutrient for growth of water hyacinth and this can be controlled by establishing physical and biological soil and water conservation strictures, conducting afforestation program on bar land areas and buffering the lake area using vegetation. This may be attributed to the lower supercooling and freezing points Siddiqui et al. (2021). Previous studies by (Iverson et al., 2019)and (Walker et al., 2017) have shown that water hyacinth can invade different water bodies across the Lake surface, and both northern and southern temperate zones are suitable for its invasion, which is consistent with our results.

The relative abundance of submerged aquatic plants has slowly declined in recent decades, providing evidence that changes in climate and land use are impacting the composition of aquatic plant communities (Ge et al., 2018). The invasion of water hyacinth on the surface of the lake is the reason for decline of submerged aquatic plants. Extensive management of the invasive weed can be the best option to increase the abundance of submerged aquatic plants in the study area. Warmer temperatures can stimulate organic matter mineralization in lake sediment (Gudasz et al., 2010), modify bicarbonate concentrations, and increase the likelihood of water hyacinth infestations in lakes (Shi et al., 2017). Furthermore, altered land use amplifies nutrient loading in lake habitats, hastening the water hyacinth invasion process (Davis et al., 2010). The invasion of water hyacinth on the surface of the lake minimizes the light entering to the bottom part of the lake by its dense mat overplayed on the surface of the lake. The mineralization of organic matter provides essential nutrients for growth of water hyacinth and nutrient availability for submerged aquatic species was minimized. To restore submerged aquatic plants the invasion of water hyacinth should be managed since it can compete and reduce the population in the lake. The proliferation of water hyacinths impedes the growth of submerged aquatic plants by reducing available light (van Gerven et al., 2015). Water hyacinth blooms generally have less effect on floating-leaved or free-floating species, which have photosynthetic leaves at the water surface, than they do on submerged species, thereby increasing the propensity for water hyacinth invasions (Kim & Nishihiro, 2020).

As temperatures raise, the photosynthesis rate of invasive species increases, promoting high growth and invasion rates in lakes. This increase in photosynthesis causes high biomass production of the weed and eutrophication of the lake. The ecosystem energy balance was affected due to over growth of one species which affect the ecosystem service and function. The invasion of the lake by water hyacinth minimizes the species composition which affects the ecosystem health of the lake. The shallowness of the lake near the shore provides easy access to nutrients that support the rapid growth of these species (Xie et al., 2019). These findings align with a study by (Beaury et al., 2020), which found that climate change, manifested by rising temperatures, strongly influences the invasion of non-native species and should be considered in their management. Similarly, Hussein and Estifanos (2023)found a correlation between temperature and rainfall fluctuation and the increased occurrence and habitat shift of the invasive species Opuntia ficus-indica (L.).

The study’s findings suggest that an increase in temperature enables water hyacinth to occupy a greater area than native species due to the high metabolic activity and organic matter mineralization, which provide the necessary nutrients for the weeds to invade the lake easily. These results correspond with those of (Li et al., 2023), who found that increasing temperatures resulted in an increased invasion of T. diversifolia and B. balsamifera, attributed to more sunlight and photosynthesis. Similarly, Penfound et al. (2022) discovered that temperature increases highly affected the invasion of D. antarctica, C. quitensis, and P. annua, with greater temperature increases facilitating more rapid species expansion in the Antarctic Peninsula and surrounding islands. Water hyacinth was invasive plant species in which its growth and invasion was highly affected by temperature and rainfall fluctuation. As the result of the study indicates increasing in temperature and rainfall increase the invasion increase the invasion of water hyacinth.

The seasonal increase in rainfall caused by climate change has significant direct effects on the composition and phenology of invasive plant communities (Guo et al., 2020). The fluctuation of rainfall facilitates the composition, growth, and invasion of water hyacinth (Prevéy & Timothyd, 2014). The increase in rainfall and temperature favor the existence of water hyacinth because water hyacinth can easily adapt the fluctuation of temperature and rainfall than other species. Fluctuation of temperature and rainfall allow dominance of water hyacinth on the surface of the lake affecting the phenology of plant community in the lake. This could be due to heavy rainfall and subsequent runoff removing nutrients from various land use systems. The availability of nutrients resulting from high rainfall facilitates the growth and invasion of water hyacinths. These findings align with those of (Raymundo et al., 2021), who discovered that rainfall fluctuations caused by climate change increase the community composition of non-native invasive species. Similarly, (Tripathi et al., 2019) found a significant correlation between invasive species and anomalies, revealing the affinity of invasive species towards warmer, drier, and wetter locations. The results also correspond with those of (Yu et al., 2019), who found that E. crassipes can invade higher latitudes due to climate warming and water eutrophication trends.

5. Conclusion and policy implication

Climate change is a significant factor in governing the variety of biological, physical and chemical mechanisms that affect the development, distribution and sequence of invasive species across the globe. The invasion of species and climate change are two major environmental factors that can modify ecological systems. Based on the study’s findings, it is possible to infer that there has been a change in land-use and land-cover on the lake’s surface.

The study’s findings point to a positive increase in the rate of water hyacinth invasion and a negative rate of change in areas that are used as crops and barren land. The invasion of water hyacinth and climate change minimize the fish resource and the phytoplankton composition of the like which had an implication to loss of biodiversity in the lake. The invasion of water hyacinths in the research area has also reduced the area covered by water bodies. The spread of water hyacinth has caused a sizeable amount of the lake area to become a wetland.

The study’s outcomes reveal the significant impact of climate change on promoting the invasion of water hyacinths. The rise in temperature provides a favorable environment for the weed to spread its coverage, thanks to the escalated rate of photosynthesis and organic matter mineralization. Regions of the lake that experience high precipitation were attacked by water hyacinths. Thus, this signifies that variations in rainfall levels within the lake’s vicinity influence the weed invasion on the lake’s surface and its surrounding regions.

To minimize the impacts of water hyacinth invasion on biodiversity composition, ecosystem services, and the livelihoods of communities, the existing physical removal with mass mobilization should be substituted with encouraging positive use of the invasive weed, using the weed for biofuel, energy and bio fertilizer. Comprehensive management strategies need to be developed by the government, policymakers, and environmentalists especially considering the positive use of water hyacinth. These management strategies should take into account the existing climate change scenario. Furthermore, further research is necessary to identify the best management practices for minimizing the effects of water hyacinth invasion on the diversity frequency dominance and important value index of species found in the lake. The research implies that climate change can facilitate the invasion of water hyacinth in the study area and in lakes found in the world.

Public interest statement

Ethiopia is endowed with water source and the century is termed as ”water tower at the horn of Africa”. The water sources of the country were highly affected by natural and anthropogenic factors. Climate change and invasive species were responsible for disturbance of lakes and rivers found in the country. Climate change which is supported by unlimited human need cause for eradication of some lakes and rivers. Climate change can facilitate the invasion of water hyacinth which affects ecosystem, biodiversity and socioeconomic activities in the study area.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are openly available in the hand of the researcher and ready to provide it in the time of need.

Additional information

Notes on contributors

Tesfaye Bayu

Tesfaye Bayu is a lecturer in the Department of Natural Resources Management, Debre Markos University Burie Campus and has MSc in land resource management from Bahir Dar University, and PhD from Diponogoro University. He has taught several courses for general forestry, natural resources management, plant science and horticulture students. His areas of interest are conducting research on status of food security, soil fertility management, environmental management, climate change mitigation and adaptation; invasive species land resource management, watershed management, etc.