Aspects of paleoclimatic and paleoceanographic evolution of the north Aegean Sea through the Holocene are revealed by the study of quantitative variations in planktonic foraminiferal, pteropodal, and palynomorph assemblages; the isotopic composition of planktonic foraminifera; and hydrographic-related indices, extracted from two high-sedimentation rate cores from the North Aegean Trough. Focusing on the last ~10 cal ka BP, the current Holocene subdivision (Greenlandian, Northgrippian, and Meghalayan) confirms the traditional understanding of an evolution from wetter (Greenlandian) to gradually drier (Northgrippian and Meghalayan) climatic conditions and further highlights the role of changing seasonality during this time. The most warm and humid phase corresponds to the time of the sapropel S1 deposition (9.6–6.1 cal ka BP). The Holocene climatic instability of the study area is further supported by six episodes of brief cooling (North Aegean cooling; NAEGC6–NAEGC1) centered at 9.30, 8.05, 7.05, 4.55, 3.55, and 2.05 cal ka BP, reflected by significant faunal changes and oxygen isotope enrichments. These cold/arid events are coeval with equivalent cooling events that have been described in different basins of the Mediterranean Sea, while signal similarities with equivalent changes in the intensity of the Siberian high suggest a climatic link between the studied area and the high-latitude areas.

Cetacean stranding reports in the North Aegean Sea were recorded since 1998 from Strimonikos Gulf in Chalkidiki up to Alexandroupoli on the Turkish border and in a few northern Aegean islands. On site, the specimens were examined to identify species, gender, approximate age and, when possible, cause for stranding. A total of 26 filled stomachs of five cetacean species collected since 2002 were analysed: bottlenose dolphins Tursiops truncatus (N = 8), common dolphins Delphinus delphis (N = 8), harbour porpoises Phocoena phocoena (N = 5), striped dolphins Stenella coeruleoalba (N = 4) and Risso's dolphins Grampus griseus (N = 1). From the analysed stomachs it was found that the bottlenose dolphins fed mainly on snake blenny Ophidion barbatum (34%), bogue Boops boops (22%) and round sardinella Sardinella aurita (13%); common dolphins on round sardinella (17%), picarels Spicara spp. (10%) and Cocco's lantern fish Lobianchia gemellaris (9%); harbour porpoises on Gobidae (four-spotted goby Deltentosteus quadrimaculatus 41% and black goby Gobius niger 37%) and round sardinella (7%); striped dolphins on Myctophydae (Madeira lantern fish Ceratoscopelus maderensis 51%), and on Pfeffer's enople squid Abraliopsis morisii (10%) and bogue (8%); and Risso's dolphin exclusively on Teuthidae (31%), the umbrella squid Histioteuthis bonellii (30%) and the reverse jewel squid H. reversa (14%). The present work represents the first attempt to investigate the diet up to species level for several cetaceans in Greek waters and for harbour porpoises stranded in the Mediterranean Sea.

In the present study gut type was described and intestinal indices (i.e. mean gut length, relative gut length and Zihler's index) were estimated and compared for 58 fish species from the North Aegean Sea. A strong relationship between gut length (GL) and total length (TL) (significant relationships (P < 0.05) for 52 species) was found, whereas the hypothesis of the allometric growth of GL with TL was confirmed for 27 out of the 52 species. For the same TL, GL differs for species with different feeding habits (in omnivores > carnivores), as previously reported. Finally, for the same TL, GL also differs for species with different habitats (reef-associated > pelagic > benthopelagic > demersal) and gut types (Z-shaped with multiple loops > looped Z-shaped > Z-shaped >straight > convoluted > short with spiral valve).