Midlittoral polychaete communities in the Eastern Mediterranean Sea: new information from the implementation of the Natural Geography in Shore Areas (NaGISA) protocol and comparisons at local and regional scales

Abstract

The aim of this study was to attempt to fill current knowledge gaps on midlittoral Mediterranean biodiversity at local and regional scales, by using benthic polychaetes as a model taxon. Two different data sets were analysed: (i) a quantitative data set from the two Natural Geography in Shore Areas (NaGISA) study sites in Crete and (ii) a qualitative data set from multiple sites across the Mediterranean. At the local scale, the results provide evidence that (i) discrete species communities are formed in midlittoral Mediterranean habitats, which vary by geographical location and year, depending on the scale of observation; (ii) macrophyte coverage and Chl‐a are the only environmental variables associated, albeit weakly, with the above pattern; (iii) although naturally disturbed, the Cretan NaGISA sites do not seem to experience any anthropogenic stress; (iv) environmental heterogeneity and history seem to be much less important in shaping the polychaete communities than inter‐specific interactions; however, it is not possible to specify at this stage whether local or regional processes or even their interactions may shape the polychaete communities. At the regional scale, the results indicate that (i) the only factor that seems to be involved in the regional pattern is the identity of the study providing the data sets, which implies variability and bias in how research projects are carried out, from the sampling design through to data collection and analysis; (ii) the Cretan NaGISA sites may be considered as representative of the habitat in the Mediterranean, under certain conditions.

Sponge-Associated Polychaetes: Not a Random Assemblage

“…In total 13 publications provided polychaete species lists from massivesponges along the Mediterranean covering a time span of 95 years (Santucci, 1922;Pansini and Daglio, 1980;Alos et al, 1981;Koukouras et al, 1985Koukouras et al, , 1996Voultsiadou-Koukoura et al, 1987;Cinar and Ergen, 1998;Gherardi et al, 2001;Gerovasileiou et al, 2016;Pavloudi et al, 2016;Papatheodoulou et al, 2019;Çinar et al, 2019;Goren et al, 2021). In accordance with previous studies, the Mediterranean Sea was divided to five zoogeographic zones (Figure 1; Arvanitidis et al, 2002;Voultsiadou, 2009;Chatzigeorgiou et al, 2017). Literature data were incorporated into a Microsoft Excel database along with zoogeographic (study area, region, and entire Mediterranean Sea), ecological (feeding guilds), and taxonomical information.…”

Epibenthic Communities on Artificial Reefs in Greece, Mediterranean Sea

“…Consequently, this affected development-especially that of grazers of turf (filamentous) algae and cyanobacteria-might influence the abundance of other groups, such as gastropods (e.g., [32]). Algal assemblages have also been proven to affect polychaete distribution and composition [48,50]. This demonstrates once more how water turbidity recorded at the Ierissos AR might create a cascade of effects on the community structure.…”

“…For example, Ierissos receives a great amount of freshwater influx, producing an area with lower salinity and higher chl-α concentration compared to Kalymnos and Preveza. The distinctive environment of Ierissos is evidently reflected in the community composition, since polychaetes' diversity, richness, and distribution has been proven to correlate with higher chl-α concentration values and fresh water input [31,33,48].…”

Polychaetes of Greece: an updated and annotated checklist

“…In fact, regional patterns of polychaete diversity in the Mediterranean seem to be biased by researcher identity (Chatzigeorgiou et al 2017) and existing inventories are characterised by a large number of questionable species (e.g. 23.7% of the Mediterranean inventory (Arvanitidis 1994); 16% of the current Greek inventory).…”