Logistic growth and density-dependent spatial and temporal invasion predictions of non-native Tilapia, Oreochomis niloticus (linnaeus 1757), in the Ganga river (India)

Srivastava

Verma

2021

Self Cite

In order to assess the distribution pattern and understand the prevailing factors for predicting further expansion of an exotic fish Oreochromis niloticus, this study was undertaken in the Ganga river flowing through the state of Uttar Pradesh using MaxEnt model. The authors report the distribution pattern of O. niloticus and prevailing causative factors mounting the expansion of O. niloticus in the Ganges based on MaxEnt modeling technique. The presence only occurrence data-set for this invasive species was prepared from the field data and also from data collated from the authenticated publications of different fisheries researchers. The data-set was analyzed with environmental and topographical variables typically incorporating seasonal and temporal variability using MaxEnt, a maximum entropy algorithm which showed that the area under curve was much closer to 1 ( 0.999). The model predicted elevation as the most influential predictor variable with permutation importance of 69.2% followed by slope_steepness (10.1%), Tmax_1 (7.3%) and Srad_5 (6.8%). The findings from the results suggest that invasive O. niloticus tend to spread in rivers where elevation is lower as well as slope_steepness of the river is higher and thus indicated that invasion might be higher in the downstream of the river. The model suggests that topography and its derived variable are the most significant predictors for distribution of invasive O. niloticus. The results of this study also confirm that the water qualities of the Ganga river are suitable for O. niloticus and if the model is supplemented with water quality variables data, the influential predictor variable in water quality can be well investigated with permutation importance.

“…to Tilapia population prediction for future did not differ significantly when compared from MaxEnt findings tested with presence-absence data (Singh and Srivastava, 2020).…”

Section: Discussionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

MaxEnt distribution modeling for predicting Oreochromis niloticus invasion into the Ganga river system, India and conservation concern of native fish biodiversity

Srivastava

Verma

2021

Self Cite

“…Common Carp and Tilapia have constituted the major bulk of catch at most of the rivers and reservoirs. Common Carp contributed in the range of 19.7 to 38.6% in the size group of fry, fingerlings to large one up to 22.5 kg while Tilapia in the size range of 1.5g to 1.8 kg constituting 13.2 to 26.9% of total invasive fish captured (Singh and Srivastava, 2020). The length-weight correlation (r 2 ) of Common Carp has been found above 0.67 having maximum value of 1.09.…”

Section: Fish Invasions In Inland Watersmentioning

confidence: 92%

“…In this study, hyperbolic growth function by calculating logistic growth and density-dependent factors considering data fits for ten years was carried out to predict future invasion changes for next decades (Figures 4 and 5). The predictive biomass was calculated as per described methodology (Singh and Srivastava, 2020). Mean abundance by weight (MAW) was estimated for Tilapia and Common Carp for the period from 2009 to 2018 (Concrete values) and the forecasted values in MAW based predictions was then calculated as biomass for the period from 2019 to 2048.…”

Section: Future Predictive Invasion and Challengesmentioning

confidence: 99%

State of aquatic invasive species in tropical India: An overview

2021

Self Cite

India, a megadiverse tropical country is grappling with the rising trend of aquatic invasions. Out of 532 introduced non-native fish, 16 species of freshwater aquaculture and aquarium were assessed invasive by using a risk assessment protocol, ‘Fish Invasiveness Screening Test’. Six major identified invasion pathways of the aquatic invasive species were inadvertent or deliberate releases, escapes, contaminants from hatcheries, river corridors, stowaways and unaided introductions. Invasion mechanism further elucidated the factors promoting successful invasion in freshwater ecosystems. For predictive future performance of invasive fish, the concrete and predictive values based on mean abundance by weight was calculated. Over 28.67% and 29.02 % persistent increased yield of the invasive Tilapia and Common Carp respectively was predicted in the Ganga river in the coming decades. Single species Tilapia invasion facilitated multiple species fish invasion, manifesting in invasion meltdown. The trophic changes due to fish invasion exhibited biotic homogenization with trophic downgrading. Aquatic invasive species were found highly competitive interacting with native species causing serious biodiversity loss, health hazards, and economic damage consequently affecting the ecosystem services. In spite of available regulatory approaches and guidelines to manage aquatic invasive species, fish invasion has been on the rise. This paper suggests modifications and stringent implementation of the existing regulatory mechanisms besides adopting linkages, cutting-edge research on invasion science and modern molecular containment tools for effective management.

“…Although invasive species possess many attributes that can explain its ability to spread and survive even in new habitats and harsh environments, no study has identified processes that might explain its restricted pattern of superabundance. A few researchers have tried to estimate invasive species biomass and abundance on the basis of the mean abundance by weight (Dominguez et al, 2020;Singh and Srivastava, 2020). Several models estimating spatial and temporal variation in population density are increasingly used to track shifts in population distribution subject to environmental and climatic changes (Harsch et al 2014;Thorson et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Invasion meltdown and burgeoning threats of invasive fish species in inland waters of India in the era of climate change

Srivastava

2021

Self Cite

Cyprinus carpio, Oreochromis niloticus and Clarias gariepinus are the most abundantly captured invasive fish species in the mid-stretch of the Ganga river. Fish yield and biomass data based on mean abundance by weight was calculated using algorithms and spatio-temporal population dynamics model for future prediction of these invasive fish species. Temporal biomass forecast based on mean abundance by wieght for the period from 2020 to 2029 was determined. The findings of this study predicted fish yield of 176 ± 16.33 kg km-1 day-1C. carpio and 55.43 ± 6.4 kg km-1 day-1 O. niloticus during 2029 which might result into 117.87% and 116.9% rise in temporal biomass of Common Carp and Tilapia respectively in a decade's time while 139.2% rise in temporal biomass was predicted for the invasive African catfish. The yield of invasive Common Carp, Tilapia and African Catfish was correlated with rainfall and temperature data using ANOVA and we found that variance was F = 1.36; p = 0.263 for C. carpio; F = 1.60; p = 0.326 for O. niloticus and F = 1.63; p = 0.101 for C. gariepinus, indicating that variance was very close for Tilapia and African Catfish. The observed values of variance indicated that climatic changes had more impact to these two species than to the Common Carp. The concrete and forecast values were calculated considering 95% lower and upper level of confidence, which was significant (p <0.05) and the annual regression was found to be p < 0.464, p < 0.419 and p < 0.499 for C. carpio, O. niloticus and C. gariepinus, respectively. Further, interactive performance of invaded C. carpio, O. niloticus and C. gariepinus was also assessed for understanding invasion meltdown. The results of mean abundance by weight based yield forecast of invaded Tilapia, Common Carp and African Catfish for the period of 2020 to 2029 suggest a stable production in the Ganga River in years to come. It also manifests a positive pattern of invasion in the times of climate change displaying invasion meltdown. This suggests increased pressures of fish invasions on temporal and spatial scales, and imposing new management challenges for freshwater ecosystems.