Ecosystem services trade-offs informing impacts of marine aquaculture development in the southern Caspian Sea.

Humans have always benefited from marine ecosystems and the use of their services has increased over time. The principal challenge of managing ecosystem services is that they are not independent of each other. Attempts to optimize a single service have often led to the reductions or losses of other services; in other words, they are "traded-offs". Based on the purpose of assessing the impacts of marine aquaculture development in the Southern Caspian Sea, 3 management scenarios were utilized to model 3 categories, including marine aquaculture, Water Quality (WQ) and Habitat Risk Assessment (HRA) through marine Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST). Marine aquaculture model was first considered for Oncorhynchus mykiss that the results were as follows: in the baseline scenario with 9 farms, the amounts of the total weight of fish produced and Net Present Value (NPV) measured during 1 year equaled 1970 tons and 2,247,000 dollars; in the conservation scenario with 4 farms, their amounts were 800 tons and 1 million dollars; in the expansion scenario with an increased number of farms (20 farms), their amounts were estimated to be 4000 tons and 5 million dollars, respectively. The results of the marine aquaculture model were utilized as the inputs both to WQ (amount of BOD released from each farm) and HRA (habitats of four species of fish (Rutilus frisii kutum, Acipenser stellatus, Acipenser persicus, and Huso huso) models. The results revealed 41%, 16%, and 60% of WQ reductions and 35%, 20%, and 45% of HRA changes in the baseline, conservation, and expansion scenarios, respectively. Considering the current production of 9 existing farms (1970 tons per year) and the impact of this production on water quality (41%) and habitat risk (35%), it is recommended to reduce this production volume and doing aquaculture development in the Southern Caspian Sea without considering and managing negative consequences can have dangerous consequences for this sensitive ecosystem.

Responses of surface water quality to future land cover and climate changes in the Neka River basin, Northern Iran.

The spatial and temporal dimensions of environmental impacts of climate and land cover changes are two significant factors altering hydrological processes. Studying the effects of these factors on water quality, provides important insight for water resource management and optimizing land planning given increasing water scarcity and water pollution. The impact of land cover and climate changes on surface water quality was assessed for the Neka River basin in Northern Iran. The widely used Soil and Water Assessment Tool (SWAT) was applied for pollutant modeling, and was calibrated using the Sequential Uncertainty Fitting (SUFI-2) algorithm. An ensemble of 17 CMIP5 climate models under two IPCC greenhouse gas emission scenarios were selected, and future land cover change (LCC) was modeled based on the evolution that occurred in the last decades. We simulated the impacts of climate change (CC) and LCC on sediment, nitrate, and phosphate for the 2035-2065 time slice. The annual loads of sediment, phosphate, and nitrate are projected to decrease under both CC scenarios based on the inter-model average, and generally follow a pattern similar to the change in river discharge. Nitrate concentrations show an increase across all seasons, while the sediment and phosphate concentrations increase in winter and autumn under CC conditions. Results indicate that pollutants are expected to increase under LCC alone, mainly due to the expansion of the cultivated areas. Overall, it seems CC has a greater impact than LCC on the variation of water quality variables in the Neka River basin. With a combined change in climate and land cover, the annual nitrate concentrations are expected to increase by + 19.7% and + 17.9%, under RCP 4.5 and RCP 8.5, respectively. The combined impacts of the CC and LCC caused a decline in the annual sediment and phosphate concentrations by -10.1% and -2.2% under RCP 4.5 and -9%, and -3.2% under RCP 8.5, respectively.

Interactive impacts of climatic, hydrologic and anthropogenic activities on watershed health.

The current study aimed to comprehensively assess the potential watershed health (WH) using an adapted reliability, resilience and vulnerability (RelResVul) framework for the 24 sub-watersheds of Shazand, Markazi Province, Iran. Towards this goal, the appropriate criteria and acceptable corresponding thresholds were adapted to calculate the main WH indictors of reliability (Rel), resilience (Res) and vulnerability (Vul). Accordingly, the RelResVul framework was conceptualized and customized for five criteria of standardized precipitation index (SPI), normalized difference vegetation index (NDVI), soil erosion, and low and high flow discharges. The effect sizes of used criteria and indicators on the Shazand WH status were also determined. Consequently, the status of Rel, Res and Vul indicators and integrated WH status were mapped for four years of 1986, 1998, 2008 and 2014 and for the whole watershed by developing an integrated watershed health index (IWHI). Finally, the change detection approach was applied to determine the trend of changes in IWHI during last three decades. The results approved the high variability in effectability of Rel, Res and Vul indicators and integrated health status of the Shazand Watershed from the selected criteria in study four years. The results revealed that in the all study years, the Rel indicator almost had the higher contribution rate (≥34%) in the Shazand WH. None of sub-watersheds in the study years were assessed in a healthy status in terms of IWHI based on the RelResVul framework. In terms of WH change detection over the study periods, WH was found to declining by some 4% in the periods of 1986-1998 and 1986-2008 due to impact of industrialization and urban development. Whilst, the health status was non-significantly improved in other study periods. The present procedure can be supposed as a screening tool for a directive and efficient management of the watersheds.