| DIVERSITY OF FISH LARVAE COMMUNITIES ACROSS THE SUBTROPICAL CONVERGENCE ZONE OF THE SARGASSO SEA A ZOOGEOGRAPHICAL ANALYSIS COMBINING MORPHOLOGICAL AND GENETIC IDENTIFICATION TECHNIQUES |
| AYALA, DANIEL, Section for Ocean Ecology and Climate, DTU Aqua, Technical University of Denmark, Charlottenlund, Denmark, 2720, djay@aqua.dtu.dk; Munk, Peter , Section for Ocean Ecology and Climate, DTU Aqua, pm@aqua.dtu.dk; Riemann, Lasse, Marine Biological Section, Copenhagen University, Helsingoer, Denmark, 3000, lriemann@bio.ku.dk. |
| Diversity, abundance and distribution of larval and juvenile fish were investigated in the Sargasso Sea, employing morphologic and genetic identification. This combination of methods provided a powerful tool for biodiversity investigation, allowing a high resolution of regional fish diversity. Four stations were examined, transecting frontal zones across the Subtropical Convergence Zone (STCZ) between 24-28 degrees North. From the total of 2064 specimens collected, we molecularly examined 582 larval fish, and identified at least 119 species from 44 families. Characteristic patterns of the fish larval community were apparent. The family Myctophidae was by far the most species-rich, with at least 31 species represented. The myctophid, Notolychnus valdiviae was the most common individual collected at all stations. The four next most abundant species included two other myctophids (Lepidophanes gaussi and Ceratoscopelus warmingii), and two eel species (Nemichthys scolopaceus and Ariosoma balearicum). Species diversity between sampled stations revealed variations in communities and diversity across environmental gradients of the STCZ. The most common eel species were found concentrated in the STCZs stratified waters, while the most common myctophids showed an opposite trend, and were concentrated on the outer edges of the two frontal systems bordering the STCZ. Calculations showed levels of species diversity almost twice as high as regional values found in previous Sargasso studies. Combining morphologic and genetic identification tools allowed 80% more species to be discriminated in this study, and almost 100% more individuals could be identified to species level. Prior ichthyodiversity surveys not using this multidisciplinary approach may have under-reported actual species diversity by 80%. |
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