Biology subjects

Agiadi, K.

Publications and source records attributed to Agiadi, K..

5 recordsLinked to original sources

bioRxiv2025

Climate versus human impacts on the marine fauna of the Mediterranean Sea during the pre-industrial period

Historical baselines are essential for evaluating the cumulative impacts on modern marine ecosystems, particularly in regions such as the Mediterranean, where human activities have been intensive for millennia and climate change is accelerating. However, quantitative evidence of historical impacts remains fragmented. In this study, we investigate changes in the presence, abundance and body size of the Atlantic bluefin tuna, gilthead sea bream, banded-dye murex and turbinate monodont across the Mediterranean Sea from 130,000 years Before Present until the Industrial Revolution (1850 AD), using geological, archaeological, and historical records. Our results reveal significant temporal shifts in the abundance and body size of the banded-dye murex, Atlantic bluefin tuna and gilthead sea bream. Environmental factors, particularly seawater temperature, were the primary drivers of abundance and size in Atlantic bluefin tuna in the past. Human activities, especially exploitation, influenced the abundance of banded-dye murex and Atlantic bluefin tuna, as well as the body size of gilthead sea bream. These findings underscore the importance of integrating long-term ecological data to better understand the interplay between climate, human pressures and ecosystem dynamics.

ecology↗

bioRxiv2025

Commercially Relevant Species in the Mediterranean Sea: A Perspective from Late Pleistocene to the Industrial Revolution

The Mediterranean Sea is the worlds second-largest biodiversity hotspot and has been impacted by several environmental changes and human activities since pre-historic times. We present the results of a systematic review of the published literature on the nature and extent of these impacts on the ancient-historic Mediterranean marine ecosystems. We aim to provide an overview of the current state of knowledge and identify research gaps about climate and human-activity impacts on commercially relevant species of marine mammals, fishes, and molluscs in the Mediterranean Sea over the last 130 thousand years until the Industrial Revolution (the year 1850). In most of the reviewed publications, species were used as indicators of past climatic conditions or human subsistence strategies. A research gap remains, however, in quantifying their effects on marine ecosystems. Based on our results, we identify data trends in time and space and by functional group. Data are available primarily from the Holocene rather than the Late Pleistocene, reflecting a heterogeneous availability of records. The Adriatic Sea is underrepresented among subregions, which may indicate variability of accessible data between subregions, rather than an actual lack of information. Marine mammals were less studied than fishes and molluscs in the three subregions. Despite the lack of standardised guidelines to conduct studies and subsequent variability in information, this work provides novel insights into the importance of studying the evolution of research focused on past environmental and anthropogenic impacts in the Mediterranean Sea. Research efforts need to be balanced to examine both economically and ecologically valuable species in the marine ecosystem. We also reinforce the need for uniform approaches to gather data in a usable format for posterior research.

ecology↗

bioRxiv2024

Pelagic ecosystem responses to changes in seawater conditions during the Middle Pleistocene Transition in the Eastern Mediterranean

AbstractMesopelagic fishes play a crucial role in the global carbon cycle through their diel vertical migration (DVM), but the impacts of neither natural nor anthropogenic climate change on DVM patterns are currently known. Studying the geological past can elucidate changes in DVM patterns under swelling climate pressure and allow estimating the impacts of the current climate crisis. We present a multi-proxy, ecosystem-level assessment of paleoenvironmental changes in the Eastern Mediterranean during the Middle Pleistocene (marine isotope stages MIS 23-18; 923-756 ka B.P.) and use the carbon and oxygen isotopic composition of fossil fish otoliths to assess the impacts of these changes on DVM and their possible implications on the biological pump. Temperature was the primary driver of ecosystem change during MIS 21 interglacial, whereas productivity became a dominant factor in MIS 19 interglacial. Responses of organisms throughout the water column varied. Our results indicate increased productivity across trophic levels during MIS 19, which affected foraminiferal biomasses, but did not inhibit fish DVM. In contrast, the early MIS 21 warming led to a reduction in DVM by mesopelagic fishes and consequently a drop in biological pump efficiency.

systems biology↗

bioRxiv2024

Late Miocene transformation of Mediterranean Sea biodiversity

Understanding deep-time marine biodiversity change under the combined effects of climate and connectivity changes is fundamental for predicting the impacts of modern climate change in semi-enclosed seas. We quantify the Late Miocene-Early Pliocene (11.63-3.6 Ma) taxonomic diversity of the Mediterranean Sea for calcareous nannoplankton, dinocysts, foraminifera, ostracods, corals, molluscs, bryozoans, echinoids, fishes, and marine mammals. During this time, marine biota was affected by global climate cooling and the restriction of the Mediterraneans connection to the Atlantic Ocean that peaked with the Messinian Salinity Crisis. Although the net change in species richness from the Tortonian to the Zanclean varies by group, species turnover is greater than 30% in all cases. The results show clear perturbation already in the pre-evaporitic Messinian (7.25-5.97 Ma), with patterns differing among groups and sub-basins.

paleontology↗

bioRxiv2022

Palaeontological evidence for community-level decrease in mesopelagic fish size during Pleistocene climate warming in the eastern Mediterranean

Mesopelagic fishes are an important element of marine food webs, a huge, still mostly untapped food resource, and great contributors to the biological carbon pump, whose future under climate change scenarios are unknown. The shrinking of commercial fishes within decades has been an alarming observation, but its causes remain contended. Here, we investigate the effect of warming climate on mesopelagic fish size in the eastern Mediterranean Sea during a glacial-interglacial-glacial transition of the Middle Pleistocene (marine isotope stages 20-18; 814-712 Kyr B.P.), which included a 4 {degrees}C increase of global seawater temperature. Our results based on fossil otoliths show that the median size of lanternfishes, one of the most abundant groups of mesopelagic fishes in fossil and modern assemblages, declined by ~35% with climate warming at the community level. However, individual mesopelagic species showed different and often opposing trends in size across the studied time interval, suggesting that climate warming in the interglacial resulted in an ecological shift toward increased relative abundance of smaller-sized mesopelagic fishes due to geographic and/or bathymetric distribution range shifts, and the size-dependent effects of warming.

paleontology↗