Copepods key traits in diverse habitats of tropical waters

Abstract

Copepods are the dominant marine zooplankton and perform important functions in the marine food web. However, copepod traits have not been studied in many waters. We studied the copepod community under influence of the Mekong River and the Southern Vietnamese coastal upwelling, based on their functional traits, during the southwest monsoon period in 2016. Fourteen trait categories of four key functional traits (trophic-groups, feeding-types, reproductive-strategies and diel migration) of copepod data were analyzed to investigate how environmental gradients impact on their distribution and abundance among the four defined habitats: Mekong River (MKW), upwelling (UpW), nearshore (OnSW) and offshore waters (OSW). There were seven functional groups identified in the study waters based on multiple correspondence analysis of distribution, abundance and traits of 139 copepod species. Herbivorous, current-feeding and sac-spawning copepods were dominant in all habitats with the highest abundance in OSW. Specifically, herbivorous species dominated in MKW and UpW, whereas omnivorous species dominated in OnSW and OSW. Sac-spawners dominated in all habitats, but decreased from MKW and UpW to OnSW and lowest in OSW. Cruise feeders were 2-fold higher than ambush feeders in the UpW, but the opposite was observed in the other habitats. The results suggest that impacts of Mekong River and coastal upwelling led to distinctive copepod assemblages with specific functional traits.

Copepod vertical diel migration on the continental shelf of South Central Vietnam

“…Compared to the previous study (Doan Nhu et al, 2022) Among the adult copepod previously reported as having strong migration (Oncaea media and Triconia conifera), Doan Nhu et al (2022) found that Triconia conifera migrated, but we confirmed that both species (Table 4) have medium DVM (dz ~ 14−17 m). There was probably no DVM for Oithona nana, Paracalanus parvus, and Parvocalanus crassirostris as they had inconsistent dz in migration (Table 4).…”

“…In a previous publication (Doan Nhu et al, 2022), two copepodite genera had short migrations, Paracalanus, and Oncaea, while Oithona and Corycaeus migrated long distances (dz = 25.6). The present study confirmed the two copepodite genera to have short to long DVM while Oithona and Corycaeus only showed migration at LT2.…”

“…In addition to the four copepodite genera, we found many other copepod juveniles also having DVM (Tables 2, 3). Previous research (Longhurst,1985;Doan Nhu et al, 2022) revealed the juvenile copepod migrated around the Chl-a max layers. In the present study, Chl-a max was at 20−100 m and as was the high abundance of juveniles.…”

“…Cho & Ky (1994) found the impacts of tide and seasons on the vertical migration of zooplankton in Nha Trang Bay. Recently, traitbased research on copepods revealed DVM patterns of 4 copepodite genera and 8 copepod species in south Vietnam (Doan Nhu et al, 2022). In the present stud, our investigation was conducted to understand and/or confirm the diel migration of zooplankton species in Vietnam and to understand zooplankton structure changes over 24 hours as a result of vertical migration.…”

The Spatial Distribution of Copepod Functional Traits in a Highly Anthropized Mediterranean Coastal Marine Region

“…For the former three species, the populations begin to increase at the onset of the stratification period and reached peaks during the shallowest stratification period [43]. We observed that FG1 was more abundant under the conditions of a high chlorophyll a concentration, which typically characterize inner shelf stations during summer [77,78]. This seasonal preference could be possibly explained by the feeding strategy of the FG1 species, which feed through currents carrying phytoplanktonic cells and tending to reach high abundance along the inner shelf, where rivers provide a greater supply of nutrients.…”