2024 Red List II of Biotope complexes

The analysis of biotope complexes was carried out based on IUCN criterion C, using the SPIA methodology as good data coverage allowed for this method to be applied.

The rare biotope complex, Submarine structures made by leak­ing gases, was furthermore possible to assess also using IUCN crite­rion B2, as the limitation of this complex is situated in the Kattegat between Sweden and Denmark and is restricted in extent.

The Red List II 2024 assessment of Baltic Sea biotope complex­es reveals a concerning trend of degradation for several key habi­tats. Compared to the 2013 assessment, several biotope complexes have experienced a decline in status, highlighting the escalating pressures on these valuable ecosystems. The total list of the biotope complexes and the categories assigned to them are available in Annex 3 of the Red List II habitats report.

Overall, the Red List II 2024 results paint a daunting picture for Baltic Sea biotope complexes. The biotope complexes have ex­perienced a decline and thus an increase in the risk of collapse. This underscores the dynamic nature of these ecosystems and the complex challenges that need to be addressed for their con­servation, expressed by various anthropogenic sources of accu­mulative pressures. The lack of data for certain biotope complexes complicates the assessment and highlights the need for increased research and monitoring efforts. These findings serve as a call to action for strengthened conservation measures to protect and restore these vital components of the Baltic Sea ecosystem.

Sandbanks (1110), Reefs (1170) and Boreal Baltic Narrow Inlets (1650)

Sandbanks and Reefs were not evaluated in 2024 due to many known occurrences not reflected in the dataset and some occurrences are now questioned for their accuracy. These matters stem from the Habitat Directive reporting and therefore limit further analysis on these biotope complexes.

Boreal Baltic narrow inlets were not eligible to follow similar assessment methodology as other biotope complexes, due to HELCOM SPIA tool not having validated sensitivity scores for that biotope complex, and therefore not possible to assess the biotope complex using IUCN criterion C. This invalidates the prospects of threat categorization for the 2024 Red List II project.

Red List categories and Biotope Information Sheets

The Biotope Information sheets (BIS) were updated for those biotope complexes that were categorized as threatened during the Red List II project, meaning those assessed as Critically Endangered, Endangered and Vulnerable.

Red List II / BIS 2024	Criteria 2024	HUB code	HUB name	Red List / BIS 2013	Criteria 2013
	C1	1130	Estuaries		C1
	B2c(ii); C1	1180	Submarine structures made by leaking gases		B2c(ii)
	C1	1150	Coastal lagoons		C1
	C1	1140	Mudflats and sandflats not covered by seawater at low tide		C1
	C1	1610	Baltic esker islands with sandy, rocky and shingle beach vegetation and sublittoral vegetation		C1
	C1	1160	Large shallow inlets and bays		C1
	C1	1620	Boreal Baltic islets and small islands		C1
		1110	Sandbanks which are slightly covered by sea water all the time		C1
		1170	Reefs		C1
		1650	Boreal Baltic narrow inlets		C1