Effects of Microplastics and Metal Pollution on Bivalves from the Bulgarian Black Sea Sublittoral, with Comments on their Adaptive Capacity * Author Pramatarov, Georgi I. Department of Biotechnology, Faculty of Biology, Sofia University “ St. Kliment Ohridski ”, 1164 Sofia, Bulgaria Author Tsvetanova, Elina R. Laboratory of Free Radical Processes, Institute of Neurobiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria Author Ilinkin, Vladimir M. National Society “ Ecological Engineering and Environmental Protection ”, Sofia, Bulgaria Author Andreeva, Madlena N. Laboratory of Free Radical Processes, Institute of Neurobiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria Author Alexandrova, Albena V. Laboratory of Free Radical Processes, Institute of Neurobiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria Author Chipev, Nesho H. Laboratory of Free Radical Processes, Institute of Neurobiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria text Acta Zoologica Bulgarica 2025 2025-01-15 77 1 107 119 https://doi.org/10.71424/azb77.1.002837 journal article 10.71424/azb77.1.002837 2603-3798 16652200

Table 1. The accumulation of microplastics and trace metal elements, and the oxidative stress markers in bivalve species from representative locations of the Bulgarian Black Sea coastal zone (** – significance p<0.05; * – significance p<0.1)

	Microplastics					Oxidative Stress Markers										Trace Elements
* Units: LPO [nmoles MDA/mg protein]; PO [nmoles PC/mg protein]; GSH [ng/mg protein]; SOD [U/mg protein]; CAT [U/mg protein]; GPX [U/mg protein]; GR [U/mg pro- tein]; GST [U/mg protein]; AChE [U/mg protein] and metal concentration [ppm].
	≤25 µm	25- 100 µm	101- 200 µm	LPO	PO	GSH	SOD	CAT	GPx	GR	GST	AChE	As	Cd	Cu	Cr	Ni	Pb	Hg	Zn	Fe
Donax trunculus
St. Konstantin & Elena
Mean	10.89** 0.11		0	2.00*	9.90**	391.0**	17.89**	2.56**	1.40 21.69** 114.16			83.93	NA	0.054	19.23*	0.378	0.104	0.240	NA	8.47	137.3
SD	1.25	0	0	0.34	1.95	50.48	4.51	0.69	0.38	6.66	29.80	26.89		0.006	2.71	0.11	0.025	0.090		0.074	44.12
Varna
Mean	14.67** 8.0**		5**	0.75	10.01**	450.5**	4.800	0.99	4.187	4.170 156.593 11.429			NA	0.055	27.09**	0.145	0.071	0.275	NA	14.92	53.00
SD	5.19	0.8	0.81	0.10	1.13	42.73	0.46	0.15	0.642	0.49	17.58	0.74		0.004	0.300	0.004	0.001	0.019		0.001	0.73
Shkorpilovtsi
Mean	10.79** 0.78		1.0**	0.36	7.43	392.3**	0.59	1.17	3.45	7.23* 114.98		37.88	NA	0.077	18.14*	0.259	0.055	0.350	NA	11.04	114.65
SD	3.36	0.16	0.71	0.02	0.35	70.41	0.04	0.14	0.71	0.48	11.34	1.05		0.00	0.95	0.02	0.02	0.03		0.28	12.14
Byala
Mean	4.25	0.09	0	0.65	3.91	120.8	15.69**	1.86*	12.68** 5.05		106.03 134.36**		NA	0.073	6.79	0.113	0.000	0.039	NA	8.74	95.79
SD	1.08	0.02	0	0.08	0.43	9.96	1.07	0.30	2.53	1.10	21.44	11.88		0.001	0.013	0.001	0.000	0.002		0.044	0.57
Obzor
Mean	3.74	0.37	0	0.55	3.32	129.3	18.70**	1.62*	11.76** 7.24* 121.52 116.11**				NA	0.097*	7.79	0.025	0	0.0326	NA	10.22	27.86
SD	1.25	0	0	0.03	0.96	12.69	2.28	0.11	0.57	2.38	26.65	9.78		0.001	0.046	0.002	0	0.002		0.023	0.10
Irakli
Mean	9.0**	3.0*	1.0**	0.80	4.17	456.5**	2.13	2.55**	0.75	5.90	141.89	73.45	NA	0.06	11.13	0.34	0.00	0.01	NA	18.04	163.49
SD	0.9	0.33	0.1	0.09	2.16	20.38	1.51	0.52	0.71	1.97	14.31	8.21		0.00	0.09	0.00	0.00	0.00		0.06	1.35
St. Vlas
Mean	10.0**	2.85*	0.5	0.99	9.06**	370.8**	5.18	2.59**	1.343	3.07	153.32	11.677	NA	0.119*	29.71**	0.298	0.121	0.025	NA	14.01	166.94
SD	2.36	1.52	0.35	0.07	0.51	39.00	0.59	0.17	0.24	0.76	7.84	1.29		0.001	0.255	0.001	0.002	0.002		0.027	0.193
Slunchev Bryag
Mean	4.0	1.0	0	0.89	11.17**	330.7*	2.755	2.83**	0.703	3.36 197.32** 14.793			NA	0.127*	21.20**	0.579	0.164	0.163	NA	14.10	275.89*
SD	1.41	0	0	0.05	1.12	28.00	0.24	0.25	0.23	0.53	14.88	0.99		0.012	2.590	0.062	0.009	0.006		1.430	34.446
	≤25 µm	25- 100 µm	101- 200 µm	LPO	PO	GSH	SOD	CAT	GPx	GR	GST	AChE	As	Cd	Cu	Cr	Ni	Pb	Hg	Zn	Fe
Pomorie
Mean	8.62**	0.55	0	0.54	4.166	200.69	15.17**	2.70**	10.03**	6.52	98.033	73.580	NA	0.047	7.68	0.065	0.186	0.172	NA	13.41	46.613
SD	4.35	0	0	0.03	0.35	16.15	0.15	0.09	1.53	0.44	10.10	6.93		0.003	0.017	0.001	0.008	0.109		0.036	0.260
Sozopol
Mean	6.0*	2.0	0	0.66	5.223	177.48	19.40**	3.33**	14.20**	8.55* 111.387		85.728	NA	0.214*	5.77	0.066	0.015	0.0685	NA	12.61	57.073
SD	2.25	1	0	0.05	0.58	12.00	1.72	0.19	0.96	0.98	11.93	6.75		0.129	0.032	0.000	0.002	0.001		0.028	0.574
Duni
Mean	0.84	0.11	0	0.71	4.922	179.81	21.84**	2.71**	11.81**	4.91 113.379		86.414	NA	0.049	6.39	0.029	2.765	1.866*	NA	12.93	24.145
SD	0.15	0	0	0.09	0.68	28.00	1.91	0.19	1.21	0.72	13.49	11.13		0.002	0.054	0.002	0.057	0.008		0.051	0.037
Arkutino
Mean	2.39	0.11	0	0.60	4.179	423.89** 2.853		2.21**	1.480	9.46* 93.921		11.108	NA	0.054	5.98	0.053	0.016	0.068	NA	10.22	46.241
SD	0.2	0	0	0.05	0.81	22.00	0.44	0.13	0.37	1.80	18.17	1.67		0.002	0.015	0.002	0.003	0.004		0.042	0.197
Ahtopol
Mean	8.42**	1.08 0.72**		0.69	9.882** 370.33* 2.224			2.72**	2.264	4.09 116.581		19.207	NA	0.230	18.71*	0.101	0.143	0.306	NA	10.07	41.553
SD	3.67	0.37	0.52	0.02	0.75	18.00	0.28	0.13	0.38	0.58	10.08	1.67	0.10438 0.43641 0.00265 0.01428 0.00786							0.04 0.14739
Cerastoderma glaucum – Varna Lake
Mean	1.40	0.49	0.40	0.66	8.08**	217.68	4.820	2.22*	3.755	7.74* 167.06		27.496	4.32	0.590*	13.89*	4.80**	24.52**	4.45** 1.66** 66.08* 957.57**
SD	0.22	0.22	0.18	0.63	1.81	12.57	2.36	1.06	1.26	1.78	9.18	6.19	0.37	0.02	0.18	0.05	0.55	0.28	0.10	0.71	37.95
Mya arenaria – Varna Lake
Mean	2.47	0.53	0.07	0.46	6.34	270.67	2.975	1.973	1.552	34.76 203.83		18.53	3.33	0.570	14.83	3.27	3.68	3.85	0.23	184.11	322.02
SD	0.48	0.16	0.007	0.07	0.65	27.67	0.328	0.287	0.157	2.112 10.18		1.08	0.59	0.07	2.45	0.38	0.66	0.53	0.05	32.41	17.88
Mytilus galloprovincialis – Varna Lake
Mean	1.44	1.11	0.33	3.93	5.71	209.22	1.09	0.380	4.10	5.09	193.7	11.83	2.44	6.825	8.03	2.18	2.76	3.05	0.26	150.61 683.44
SD	0.67	0.29	0.16	0.37	0.38	52.25	0.09	0.06	0.23	0.4	0.88	1.17	0.37	5.925	2.61	0.07	0.92	0.26	0.01	49.43	451.84