This study is focused to the aquatic environments of the Sian Ka’an reserve, a World Heritage Site. We applied protocols recently developed for the rapid assessment of most animal taxa inhabiting any freshwater system, by using light traps, and DNA barcodes, represented by the mitochondrial gene Cytochrome Oxidase I (COI). We DNA barcoded 1037 specimens of mites, crustaceans, insects, and fish larvae from 13 aquatic environments close or inside the reserve, with a success rate of 99.8%. In total, 167 Molecular Operational Taxonomic Units (MOTU’s) were detected. From them we identified 43 species. All others remain as a MOTU. For analyzing the adult fish communities, we applied the non-invasive method of environmental DNA (eDNA), and identified the sequences obtained with the Barcode of Life Database (BOLD). We found 25 fish species, and other terrestrial vertebrates from this region. No alien species was found. After a comparison of the MOTU’s from all systems, we found that each water body was unique respect the communities observed. The reference library presented here represents the first step for future programs to detect any change in these ecosystems, including invasive species, or improve knowledge of freshwater zooplankton, because most of the MOTU’s are possibly new species to science.

The main objective of this paper was description of seasonal and interannual trends in secondary production and mortality rates of the three most important Copepoda taxa in the Gulf of Gdańsk (southern Baltic Sea). Samples were collected monthly from 6 stations located in the western part of the Gulf of Gdańsk during three research periods: 1998-2000, 2006-2007 and 2010-2012. Production was computed basing on copepod biomass and mortality rates estimated according to vertical life table approach. Redundancy analysis was used to investigate relationship between secondary production and environmental conditions. Considering the entire research period there was significant interannual and seasonal variability of secondary production, mortality rate as well as abundance and biomass anomalies. Conducted analysis revealed correlation between increasing temperature and production of Acartia spp. and T.longicornis developmental stages, while older copepodites of P.acuspes showed almost negative correlation with temperature. The mortality rate estimations obtained for Acartia spp. Were highest in summer, while for T.longicornis peak was usually noted in spring-summer period. Lowest mortality rate estimations were noted in autumn and winter for almost all stages of investigated taxa.