Identifying suitable proxies for climate changeimpacts in shallow Mediterranean habitats: sponge filtration not a ready-to-use tool yet

The identi#cation of reliable proxies is crucial to undertake experimental manipulationand test hypotheses on climate change impacts. We evaluated the potential use ofsponge #ltering activity as a proxy for the e$ect of temperature (T) increase in shallowmarine habitats since: i) Porifera are ubiquitous, sessile and long-lived aquatic organisms;ii) Porifera are active #lter feeders and play a key-role in benthic-pelagic coupling;iii) #ltering activity already proved reliable to detect T e$ects on bivalves. The systematicscreening of current literature to gather data and test the assumption “T increase ->increase in sponge #ltering activity” led to a #rst list of 840 sources (title relevance level).After abstract screening, 85 documents related to Porifera #ltration or feeding activitieswere retained. Yet, information and results are highly heterogeneous in terms of purposeof study, species, habitat, methods and measured units. A high fraction of studies donot report #ltration data and less than 10% include relevant information about T.Given such dispersion of data, formal meta-analysis may not be performed and theassumption could not quantitatively be tested, thus evidencing a knowledge gap thatneeds further research e$orts. At the state of the art, sponge #ltering activity is not aready-to-use proxy for climate change.