Monitoring long-term spatial and temporal trends of the infaunal community characteristics along the shallow waters of the Mediterranean coast of Israel.

Abstract

Sandy sediment and its infauna were annually sampled along the shallow waters of the Israeli coast during the 2005-2016 period, as a part of the Israeli National Environmental Program framework, aiming to detect anthropogenic interference in that province by monitoring changes in the species composition, abundance, and diversity of the infaunal communities and in accompanied abiotic parameters: the levels of total organic carbon and a series of heavy metals and the site-specific grain size distribution. The > 250-μm fraction of the fauna was segregated from the sampled sediment and was identified to species or higher taxonomic level. Three spatial biotopes were determined based on their unique faunal composition, Haifa Bay, Haifa harbor, and the southern coast. Species homogeneity among samples of each biotope was evaluated. Temporal and spatial changes of the species composition, abundance, and diversity were calculated for each biotope, mostly revealing random annual fluctuations. Only two minor temporal trends were observed: two spatially identical and temporally different faunal communities in the southern coast biotope, distinguishing the 2005-2007 and 2008-2016 periods, and a slight increase in the number of species across time in the two Haifa Bay provinces. Total organic carbon was highly correlated to the faunal composition with the highest organic carbon levels in the Haifa harbor biotope. The biotopes' mutually occurring abundant species were sufficient to determine biotope borders and the contribution of intermittently sampled rare species, including the zoogeographically Indo-Pacific originated ones was feeble, important only to identify species migration and faunistics. Practically, three sampling sites along the Israeli shallow soft substrate, corresponding to the defined spatial biotopes, are sufficient to monitor the effect of environmental changes. Seasonal sampling twice a year is recommended as well as more accurate species identification using molecular taxonomy.