The impact of the massive mucilage outbreak in the Sea of Marmara on gorgonians of Prince Islands: A qualitative assessment

Nur Eda Topçu, Bayram Öztürk

ORCID IDs: N.E.T. 0000-0003-2734-2695; B.Ö. 0000-0001-7844-2448

Marine Biology Department, Faculty of Aquatic Sciences, Istanbul University, Istanbul, TURKEY
Turkish Marine Research Foundation, (TUDAV), Beykoz, Istanbul, TURKEY

Abstract

In autumn 2020, a large mucilaginous outbreak was recorded in the entire Sea of Marmara and lasted until summer 2021. Mucilaginous aggregates in the water column and the impacts on gorgonians were qualitatively monitored at Prince Islands. Suspending and drifting mucilaginous aggregates in several forms and sizes were present from April to July 2021. All four main gorgonian species present in the area were observed to be covered with mucilage; some colonies were still healthy, some showed total mortality, while others had partial mortality. The population of the red gorgonian Paramuricea clavata was already severely declined in the area and might be expected to be the worst impacted. Gorgonian populations in the area could potentially recover but the recurring nature of mucilage outbreaks might prevent a recovery by rejuvenation as mucilage deposition mainly impact young colonies. Considering with accelerating climate-driven changes, mucilage outbreaks would probably recur in this semi-enclosed sea with clearly altered environmental conditions. The ecological status is clearly alarming and effective measures need to be taken urgently to prevent the formation of another large-scale and long-lasting mucilage event. The implementation of the recent Action Plan for the conservation of the Sea of Marmara could highly improve the conditions if genuinely applied throughout the basin.

Keywords: Mucilaginous, sea fan, sea snot, benthos, coralligenous

References

Aktan, Y., Dede, A., Çiftci, P.S. (2008) Mucilage event associated with diatoms and dinoflagellates in Sea of Marmara. Harmful Algae News 36: 1-3.

Balkis, N., Atabay, H., Türetgen, I., Albayrak, S., Balkis, H., Tüfekçi, V. (2011) Role of single-celled organisms in mucilage formation on the shores of Büyükada Island (the Marmara Sea). Journal of the Marine Biological Association of the United Kingdom 91: 771-781.

Balkıs, N., Sivri, N., Linda Fraim, N., Balci, M., Durmus, T., Sukatar, A. (2013) Excessive growth of Cladophora laetevirens (Dillwyn) Kutzing and enteric bacteria in mats in the Southwestern Istanbul coast, Sea of Marmara. IUFS Journal of Biology 72(2): 41-48.

Cerrano, C., Danovaro, R., Gambi, C., Pusceddu, A., Riva, A., Schiaparelli, S. (2010) Gold coral (Savalia savaglia) and gorgonian forests enhance benthic biodiversity and ecosystem functioning in the mesophotic zone. Biodiversity and Conservation 19: 153-167.

Danovaro, R., Fonda Umani, S., Pusceddu, A. (2009) Climate change and the potential spreading of marine mucilage and microbial pathogens in the Mediterranean Sea. PLoS One 4(9): e7006.

Giani, M., Rinaldi, A., Degobbis, D. (2005) Mucilages in the Adriatic and Tyrrhenian Sea: an introduction. Sci Total Environ 353: 3-9.

Giuliani, S., Virno Lamberti, C., Sonni, C., Pellegrini, D. (2005) Mucilage impact on gorgonians in the Tyrrhenian Sea. Sci Total Environ 353: 340-349.

Mistri, M., Ceccherelli, V.U. (1996a) Effects of a mucilage event on the Mediterranean gorgonian Paramuricea clavata. 1. Short term impacts at the population and colony levels. Italian Journal of Zoology 63: 221-230.

Mistri, M., Ceccherelli, V.U. (1996b) Effects of a mucilage event on the Mediterranean gorgonian Paramuricea clavata. 2. Population recovery after two years. Italian Journal of Zoology 63: 231-236.

Özalp, H.B. (2021) First massive mucilage event observed in deep waters of Çanakkale Strait (Dardanelles), Turkey. J Black Sea/Medit Environ 27(1): 49-66.

Piazzi, L., Atzori, F., Cadoni, N., Cinti, M.F., Frau, F., Ceccherelli, G. (2018) Benthic mucilage blooms threaten coralligenous reefs. Marine Environmental Research 140: 145-151.

Piazzi, L., Atzori, F., Cadoni, N., Cinti, M.F., Frau, F., Pansini, A., Pinna, F., Stipcich, P., Ceccherelli, G. (2021) Animal forest mortality: Following the consequences of a gorgonian coral loss on a Mediterranean coralligenous assemblage. Diversity 13(133): 1-11.

Ponti, M., Grech, D., Mori, M., Perlini, R.A., Ventra, V., Panzalis, P. A., Cerrano, C. (2016) The role of gorgonians on the diversity of vagile benthic fauna in Mediterranean rocky habitats. Marine Biology 163: 1-14.

Ponti, M., Perlini, R.A., Ventra, V., Grech, D., Abbiati, M., Cerrano, C. (2014) Ecological shifts in Mediterranean coralligenous assemblages related to gorgonian forest loss. PLoS One 9: e102782.

Ponti, M., Turicchia, E., Ferro, F., Cerrano, C., Abbiati, M. (2018) The understorey of gorgonian forests in mesophotic temperate reefs. Aquatic Conserv: Mar Freshw Ecosyst 28: 1153-1166.

Precali, R., Giani, M., Marini, M., Grilli, F., Ferrari, C.R., Pecar, O., Paschini, E. (2005) Mucilaginous aggregates in the northern Adriatic in the period 1999-2002: typology and distribution. Sci Total Environ 353: 10-23.

Rossi, S. (2013) The destruction of the ‘animal forests’ in the oceans: Towards an over-simplification of the benthic ecosystems. Ocean & Coastal Management 84: 77-85.

Rossi, S., Bramanti, L., Gori, A., Orejas Saco del Valle, C. (2017) Marine Animal Forests. The Ecology of Benthic Biodiversity Hotspots. Springer International Publishing, Cham, Switzerland.

Savun-Hekimoğlu, B., Gazioğlu, C. (2021) Mucilage problem in the semi-enclosed seas: Recent outbreak in the Sea of Marmara. International Journal of Environment and Geoinformatics 8(4): 402-413.

Schiaparelli, S., Castellano, M., Povero, P., Sartoni, G., Cattaneo-Vietti, R. (2007) A benthic mucilage event in North-Western Mediterranean Sea and its possible relationships with the summer 2003 European heatwave: short term effects on littoral rocky assemblages. Mar Ecol 28: 1-13.

Toklu-Alicli, B., Polat, S., Balkıs-Ozdelice, N. (2020) Temporal variations in the abundance of picoplanktonic Synechococcus (Cyanobacteria) during a mucilage event in the Gulfs of Bandırma and Erdek. Estuarine, Coastal and Shelf Science 233: 1-12.

Topcu, E.N., Öztürk, B. (2015) Composition and abundance of octocorals in the Sea of Marmara, where the Mediterranean meets the Black Sea. Scientia Marina 79(1): 125-135.

Topcu, N.E., Turgay, E., Yardımcı, R.E., Topaloğlu, B., Yüksek, A., Steinum, T.M., Karataş, S., Öztürk, B. (2019) Impact of excessive sedimentation caused by anthropogenic activities on benthic suspension feeders in the Sea of Marmara. Journal of the Marine Biological Association of the United Kingdom 99(5): 1075-1087.

Tüfekçi, V., Balkıs, N., Beken, C.P., Ediger, D., Mantıkçı, M. (2010) Phytoplankton composition and environmental conditions of a mucilage event in the Sea of Marmara. Turkish Journal of Biology 34: 199-210.

Yentur, R.E., Büyükates, Y., Ozen, O., Altın, A. (2013) The environmental and socioeconomical effects of a biologic problem: Mucilage. Mar Sci Technol Bull 2: 13-15.