Lene Buhl-Mortensen

An extensive survey of anthropogenic and natural radionuclides in fish, surface sediments and sediment cores was conducted as part of the SCIRENA project. As of October 2024, there was no discernible impact of the war in Ukraine on radioactive contamination in Bulgarian waters. Seven demersal and pelagic fish species contained 137Cs activity concentrations ranging from <MDA to 0.59±0.06 Bq/kg wet weight (ww), all well below international guideline levels. Feeding habits influenced 137Cs levels, but no consistent pattern emerged. Surface sediments from 37 stations (12.5-97.8 m) contained 137Cs from <MDA to 90 Bq/kg dry weight (dw); confirming continued secondary inputs from Chornobyl-derived contamination delivered via rivers and coastal runoff. Natural radionuclides (226Ra, 228Ra, 228Th) ranged from <MDA to 40 Bq/kg dw, with one coastal 226Ra outlier at 79 Bq/kg dw. 40K ranged from 158 to 926 Bq/kg dw. Radionuclide concentrations in surface sediments correlated positively with total organic carbon (TOC) content and mud fraction (grain size < 63 mm). Four sediment cores (74.8-915 m depths) were analysed for 137Cs, 226Ra, 228Ra, 228Th, 40K and lead-210 (210Pb). Very low activity concentrations of 210Pb, 226Ra and 137Cs in three deep-sea cores limited reliable chronology for two, an observation previously not reported for Black Sea sediments. Applying 210Pb dating and the CF:CS model yielded mass accumulation rates of 1.22 and 0.134 kg m-2 y-1 for cores at 74.8 and 650 m, respectively. These results update regional baselines and support Bulgarian monitoring and food-safety management.

The health status of cold-water coral reefs on the West African coast was investigated with the main objective of obtaining knowledge of the adaptive capacity ofLophelia pertusato environmental stressors. Three coral sites were studied, in Northern Morocco, in the Morocco/Mauritania region (both in 2020) and, in the Ghana and Ivory coast region (visited in 2012, 2017, and 2019). Area cover of live colonies, explored through underwater videos, was used as an indicator of reef health and compared with the environmental variables: reef position, depth, water mass, temperature, dissolved oxygen concentration (DO), carbonate chemistry (pH, aragonite saturation (ΩAr), macronutrients and particles (visual). For a broader picture of the adaptations presented byLopheliaour results were compared with reefs in contrasting environments. Off Ghana and Mauritania healthy reefs (i.e., having areas with more than 20 % cover of live colonies) were found to reside at DO concentrations between 1.1 and 1.6 ml L⁻¹, in corrosive waters (pH 7.7 and ΩAr 1.0) with high nutrient concentrations. By contrast, the reefs off the North of Morocco, sitting in well-oxygenated waters with oversaturated ΩAr, had no or few live colonies. Our findings together with data from other studies show thatLopheliahas a wide tolerance to hypoxia and acidification, and that in relation to climate change increased temperature and silting could pose more serious threats. These findings highlight the importance of continued studies ofLopheliareefs in contrasting environmental conditions to better understand their adaptation potential to climate change-related stressors.

Crustaceans live on large colonial invertebrates for a variety of reasons, but in all cases must overcome the defenses of the host animal. We surveyed the crustaceans living on deep-sea octocorals collected during expeditions to the New England and Corner Rise seamounts (2003-2005) in the Northwest Atlantic and to the Aleutian Ridge (2004) in the North Pacific. Only a small number of crustacean species were found on octocorals in the Northwest Atlantic but a great many species, especially amphipods, were found on octocorals in the Northwest Pacific. We suggest that this disparity is due to both the differences in octocoral host dominance as well as differences in the available species pool between the two oceans.

"On the presence of Aristeus antennatus (Decapoda, Dendrobranchiata, Aristeidae) off the Canary Islands and Madeira (NE Atlantic)" published on 01 Sep 2023 by Brill.