GIS-based species distribution modeling of invasive Mnemiopsis leidyi in the southern caspian sea using satellite imageries

Abstract

Due to its unique variety of species, the Caspian Sea has great ecological-economic values and the people living on its coasts use this environmental asset as a source of income. Mnemiopsis leidyi’s invasion of this ecosystem in 1999, however, has led to instability of the ecosystem and decreased access to the services provided by it causing a decline in the population of Kilka fish and in the fishing industry. Accordingly, the present study attempted to carry out spatial modeling of M. leidyi using Multi-Criteria Evaluation (MCE) and Maximum Entropy (MaxEnt) models in summer and autumn. The main goal of comparing these two models was to find the best distribution sites of M. leidyi as an inhibiting species for the ecosystem services. The modelling was based on the following variables including: chlorophyll a concentration, photosynthetic active radiation (PAR), water temperature, turbidity, concentration of nitrogen, phosphorus, oxygen, salinity, sea level anomaly, depth, distance from the coast and bottom slope on Mazandaran coasts of Iran in the southern basin of the Caspian Sea. The findings indicated that the most favorable distribution of M. leidyi was in summer near the central (sub-region N 6563 in Behshahr and 6463 in Babolsar (and eastern coasts (sub-region N 6663 in Noshahr), and the least favorable distribution was near the western coast (sub-region N 6163 in Ramsar). In autumn, however, all the coastal zones had a high level of favorability for the viability of Mnemiopsis leidyi. ‘Distance from the coast’ and ‘depth’ were identified as the most important variables explaining the variation in the distribution of M. leidyi and helping to identify the favorable areas for the viability of M. leidyi in summer and autumn. The obtained results can help to understand better the behavior of M. leidyi, its spatial and temporal distribution, as well as to improve the ecosystem services in the southern basin of the Caspian Sea including in location of cage aquaculture sites.