MORPHOLOGICAL DEFORMITIES IN BENTHIC FORAMINIFERA TESTS AS INDICATORS OF MERINE ENVIRONMENTAL STRESS UNDER THE FRESHWATER RUNOFF

Abstract

Problem Statement and Purpose. This article represents the results of studying the lateral distribution of morphological deformations in foraminifera shells on the Roma­nian shelf of the Black Sea in connection with the influence of the freshwater inflow of the Danube River. In comparison with other organisms, features of the morphology and life cycle of benthic foraminifera offer a number of advantages for this kind of study, allowing using them to be readily used as indicators of various conditions in marine ecosystems. The purpose of this project is to study morphological features of foraminifera in connection with the influence on them of river inflow.Materials S Methods. The study area includes the northwestern part of the Black Sea shelf adjacent to the Romanian part of the Danube delta. Seventeen stations were sampled on-board the Romanian research vessel «Mare Nigrum» on 3-7 May 2012 (Cruise MN-103) within the framework of the WAPCOAST project. Sediments were recovered by 0.1 m2 Van Veen Grab. For foraminiferal analysis, the sediment samples were recovered by grab from undisturbed surface (0-2 cm) sediment. All specimens were morphologically examined and taxonomically identified. Examples of all spe­cies were imaged using Scanning Election Microscopy (SEM) at the University of Manitoba. Winnipeg. Canada.Results. 15 species of benthic foraminifera were recovered. Deformations were found in 6 species: Ammonia tepida, Ammonia compacta, Ammonia ammoniformis, Porosononion subgranosus mediteiraniens, Nonion matagordanus, and Canalifera parkerae. After statistical analysis, only 3 species gave significant correlation coef­ficients with parameters of the bottom environment: Ammonia tepida, Porosononion subgranosus mediterranicus, and Nonion matagordanus. There are two main types of abnormalities: simple and combined. The basic simple deformations are "tumors" on test chambers, breaking the spiral of the test. "Siamese twins." (accreted tests), underdevelopment and swelling of the test. In the article, only simple deformations are considered. The most common simple deformations for all the species encountered were tumors. Most often, these appear in the species Ammonia tepida. The taxonomic diversity and quantitative characteristics of foraminifera on the Romanian Black Sea shelf suggest three main factors at work. Factor 1 (the main one) is the distance from the coast. The second most significant is Factor 2, which is the eutrophication of the water column. Factor 3 is anthropogenic pollution of the bottom layer of water that enters the study area from the Danube.The Danube River creates stressfiil conditions for the individual development of A. tepida and P. subgranosus mediterranicus, and. accordingly, it may cause the morphological deformations. Deformations of the "Siamese twins" type can be used as indicators of deterioration hi the oxygen regime of the basin, and the swelling of the tests - an excess of nutrients. The findings are consistent with the results of previous studies that have shown that freshwater drainage causes stress in marine ecosystems.