The seasonal distribution, diel vertical distribution and feeding behavior of Paraeuchaeta concinna in the shallow subtropical coastal waters of eastern Hong Kong

Abstract

BackgroundPredatory copepods of the family Euchaetidae are widely distributed in polar, temperate, subtropical and tropical oceans. Paraeuchaeta concinna is the most abundant Euchaetidae in the subtropical coastal seas of Hong Kong and southern China. However, compared to Euchaetidae species in temperate and polar regions, relatively little information is available on the ecology of P. concinna and other Euchaetidae species in the subtropical oceans. This paper provides information on the seasonal abundance of P. concinna in the coastal seas of eastern Hong Kong. The diel vertical distribution of P. concinna, feeding behavior, and predation impact on mesozooplankton in eastern Hong Kong were also investigated.ResultsP. concinna is most abundant in winter and spring. Their abundance decreases shoreward, and densities are generally higher in the open waters of eastern Hong Kong than in the inner parts of Mirs Bay and Tolo Harbour. P. concinna exhibits both diel vertical migration and diel feeding rhythms in Mirs Bay. P. concinna females show strong preference for the copepods of the genera Acrocalanus, Paracalanus, and Parvocalanus, and remove ~4% of their standing stocks daily.ConclusionsThe low abundance of P. concinna during most of the year suggests it is not indigenous to coastal seas of eastern Hong Kong. P. concinna performs diel vertical migration, most likely as a strategy to avoid visual predation. Gut content analysis showed that Acrocalanus, Paracalanus, and Parvocalanus are highly preferred prey of P. concinna. A daily predation impact of ~4% of the standing stocks of Acrocalanus, Paracalanus, and Parvocalanus suggests that P. concinna may play an important role in regulating the populations of these small copepods in Mirs Bay, especially during winter and spring.

Phytoplankton community size structure, primary production and copepod production in a subtropical coastal inlet in Hong Kong

“…In addition, the appearance of larger copepods in the outer part of Tolo Harbour during winter and spring may be due to the introduction of large non-native species from offshore waters. The large calanoid copepods Calanus sinicus (Hwang & Wong, 2005;Zhang & Wong, 2013) and Paraeuchaeta concinna (Wong et al, 2012) have been shown to appear in the coastal seas of eastern Hong Kong waters during late winter and early spring only. Table 1.…”

Comparison of zooplankton communities in the East Sea, East China Sea and Philippine Sea

“…Euchaeta rimana is a subtropical, open-ocean copepod common in the plankton of North Pacific central gyre (Yen et al, 1991). The abundance of E. rimana is maximum in the oceanic waters of eastern and southeastern Hong Kong (Wong et al, 2012). This species is found in the East China Sea, where water temperature and salinity are high, supposed to be influenced by warm Kuroshio Water (Zue et al, 2006;Tseng et al, 2008).…”

Depth distribution of zooplankton in relation to limnological gradients under different stratification and interannual regimes in a deep, tropical crater lake

“…This downward movement may heighten predation risk by exposing prey species to deep-dwelling predators. These seasonal oscillations can substantially alter the pattern of distribution (Burns and Mitchell, 1980;Primicerio, 2000;Wong et al, 2012) and compel organisms to occupy suboptimal depths at the expense of their overall fitness (Gliwicz, 1986;Lampert, 1993;. The vast majority of deep African tropical lakes are permanently stratified with muted seasonality of their water columns (MacIntyre, 2012).…”