Abstract
Water temperature is an important variable in aquaculture as growth and survival of aquatic animals and molluscs strongly depend on it. Water temperature can be measured through satellites by using the infrared part of the electromagnetic spectrum and capturing the thermal emission. Satellites dedicated to Earth Observation (SEO) regularly acquire information both on land and at sea.
The aim of this study was to collect analysis ready data derived from Earth Observation to investigate the trend of Sea Surface Temperature (SST), over the last 15 years of the coastal waters facing Abruzzo Region. Knowing the trend of sea temperature could help shellfish farming management, as temperature is a key factor for the growth and survival of all organism. To provide aquaculture with useful information, the SST values were extracted at the central point of the farms, for both existing and potential sites.
Among the available satellite-derived products, the “Mediterranean Sea High Resolution and Ultra High Resolution Sea Surface Temperature Analysis" was chosen from the CMEMS repository of European Copernicus programme as a good compromise among spatial accuracy, temporal frequency and temporal coverage (Buongiorno Nardelli et al., 2013), besides undergoing gap-filling procedure.
The data spanning from 2008 to 2022 was acquired and processed using customized procedures developed within the framework of open-source software, specifically R and QGIS.
A time series analysis method was applied to the average daily values of the SST identifying the components of the additive model: trend, seasonality and random effects. The significance of the trend was evaluated through the Mann-Kendall statistical test for all farms, most of which showed a statistically significant increasing trend. A linear regression analysis applied on trend data (excluding seasonality and background noise), estimated an annual average temperature increase of 0.010 degrees Celsius over the given period (Filipponi et al., 2017).
The SST seasonality follows the atmospheric temperature one, with colder winters and hot summers in the study area.
Climate change represents a potential limiting factor for the breeding of bivalve molluscs by directly interfering with their survival and their behaviour. It has been demonstrated that the increase in temperature is also one of the main factors triggering events that lead to the accumulation of some biotoxins in European bivalves (Dhanji-Rapkova et al., 2023).
Continue monitoring the surface temperature of the seas is of fundamental importance for assessing the ecosystem health and evaluate the resilience of marine ecosystems. Satellite Earth Observation could greatly help in this objective, providing free data of sea surface waters, remotely detected, with high frequency and high accuracy.
References
Buongiorno Nardelli, B., Tronconi, C., Pisano, A., & Santoleri, R. (2013). High and ultra-high resolution processing of satellite sea surface temperature data over southern european seas in the framework of MyOcean project. Remote Sensing of Environment, 129, 1-16. doi:10.1016/j.rse.2012.10.012
Filipponi F., Valentini E., Taramelli A. (2017). Sea Surface Temperature changes analysis, an Essential Climate Variable for Ecosystem Services provisioning. 1-8. 10.1109/Multi-Temp.2017.8035255.
Dhanji-Rapkova, M., Teixeira Alves, M., Triñanes, J. A., Martinez-Urtaza, J., Haverson, D., Bradley, K., Baker-Austin, C., Huggett, J. F., Stewart, G., Ritchie, J. M., & Turner, A. D. (2023). Sea temperature influences accumulation of tetrodotoxin in British bivalve shellfish. The Science of the total environment, 885, 163905. https://doi-org.bibliosan.idm.oclc.org/10.1016/j.scitotenv.2023.163905