Changes in the northern Adriatic ecosystem and the hypertrophic appearance of gelatinous aggregates

• Published in: Science of the Total Environment Vol. 165; no. 1-3; pp. 43 - 58
• Main Authors: Degobbis, D., Fonda-Umani, S., Franco, P., Malej, A., Precali, R., Smodlaka, N.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Shannon Elsevier B.V 07.04.1995; Elsevier Science
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Environmental changes; Fundamental and applied biological sciences. Psychology; Gelatinous aggregates; Marine; Northern Adriatic; Phytoplankton community; Sea water ecosystems; Synecology; Italy; Mediterranean Sea; Adriatic Sea; Europe; Northern Adriatic; Environmental changes; Phytoplankton community; Gelatinous aggregates; Chlorophyll; Climate; Long term test; Environmental factor; Phosphorus; Mucus; Biogeochemical cycle; Oceanography; Nitrogen; Coastal zone; Aggregation; Marine environment; Species diversity; Hydrology; Seasonal variation; Phytoplankton; Chemical concentration; Population dynamics; Aggregate; Physicochemical properties; Species richness
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/0048-9697(95)04542-9

Biweekly to monthly measurements of a large number of physical, chemical, and biological parameters and visual observations (by scuba divers and underwater video cameras) were performed at 80 stations in the northern Adriatic in the framework of an ‘Alpe-Adria’ research of a phenomenon of gelatinous aggregate hypertrophy. This phenomenon was observed in the entire investigated region during the summers of 1988, 1989, and 1991 and only in the Kvarner areas in 1990. Results for some parameters were compared with available historical data series collected since 1966. Some qualitative changes in the phytoplankton communities (increased diatom contribution, decreased diversity, different dominant species) were evident during the eighties compared with the seventies. However, chlorophyl a and nutrient concentrations remained approximately at the same level. The dynamics of the Po river discharge (and nutrient inputs) during the spring, which was the critical period for aggregate formation, was different during the eighties from that in the preceding decade. An hypothesis is developed which relates the appearance of large quantities of gelatinous material to modifications of the environmental conditions (climatic, hydrology, and oceanographic).