Seasonal changes in the dietary patterns and reproductive aspects of deep-water rose shrimp Parapenaeus longirostris in the central Adriatic Sea

The deep-water rose shrimp Parapenaeus longirostris is one of the most important commercial species caught by trawl fisheries in the Mediterranean Sea. The species has a warm-water affinity and its landings are increasing in the whole basin. Detailed information on its trophic ecology, niche width and role within demersal food webs is dated or lacking in the Adriatic Sea, the most exploited basin of the Mediterranean. Therefore, to detect seasonal changes in diet and trophic levels, seasonal samplings were conducted in this area from January to December 2021, collecting 400 specimens, and integrating information from both stomach content analysis and stable isotope analyses (SIA). To identify potential links between the biological cycle of the species and fluctuations in energy demand, seasonal changes in fullness, as a proxy of feeding intensity, and gonadosomatic and hepatosomatic indices were assessed. The deep-water rose shrimp is confirmed to be a benthic feeder that predominantly preys on molluscs, crustaceans, fish, echinoderms and polychaetes. According to SIA, P. longirostris is defined as a secondary consumer. Observed seasonal dietary changes precede the reproductive periods, likely due to the need for more energetic prey.