The vertical distributions and diurnal migrations of calanoid copepods collected on the SOND Cruise, 1965 I. The total population and general discussion

Abstract

Two hundred and twelve species of calanoid copepods have been identified from a day and a night series of closing horizontal hauls made between 960 and 40 m off Fuerteventura in the Canary Islands.Displacement volumes show that the bulk of the calanoid population was at 500 m depth by both day and night, but the great majority of this population was immature. There was an increase in volume between 300 and 50 m and a decrease between 800 and 300 m by night relative to the day. This volume change is due to an upward movement in the size distribution, the mean body length per depth increasing by night above 460 m and decreasing below 500 m, which results from the migrations of abundant large species such as Plewromamma xiphias and P. abdominalis. Because of vertical migrations there were more species above 350 m by night than by day but fewer below this depth.The greatest numbers of adult calanoids were found at 40 m (day) and 50 m (night) and there were secondary numerical maxima in mid-water by both day and night. There was a decrease of over 30 % by numbers in the total night catch as compared with the day. This decrease was common to most of the genera sampled, but the reasons for it are obscure. The numbers of species considered to be contaminants at particular depths are very low. The mean body length per depth of adults increased from the surface to 900 m by both day and night. By day the number of species at a given depth increased from the surface to a maximum at 940 m; by night the maximum was at 660 m with secondary maxima at 100 m and 250 m.Previous investigations and the difficulties of making valid comparisons with the present results are discussed.

Vertical distribution and seasonal variation of pelagic chaetognaths in Sagami Bay, central Japan

“…The number of species and the diversity index decreased with depth, which is consistent with previous studies such as those from off Valparaíso, Chile (Ulloa , the Sulu and Celebes seas (Johnson et al 2006), and the waters south of the Kuroshio (Ozawa et al 2007). This pattern contrasts with that observed in many other pelagic animals, such as copepods and ostracods (Roe 1972, Angel 1993, Yamaguchi et al 2002, Shimode et al 2006, Kuriyama & Nishida 2006, in which species diversity peaks in the mesopelagic layer. In Sagami Bay, the copepod diversity in June 1996 tended to increase with depth in the upper 200 m, but reached a plateau below that layer (Shimode et al 2006), which is considerably different to the pattern observed in the chaetognaths in the present study (July 2005).…”

Arctic zooplankton do not perform diel vertical migration (DVM) during periods of midnight sun

“…Dagg (1977) postulated that, in heterogeneous pelagic environments, there is a tendency for zooplankton and their food to be patchily distributed on any spatial or temporal scale. According to Roe (1972), zooplankton is more or less randomly distributed and there is no reason to suppose that day and night catches should be equal. Day and night hauls differed during our study, for example with respect to maximum abundance of the studied taxa.…”

Spatial changes in the vertical distribution of calanoid copepods down to great depths in the North Pacific

“…Table 3 Mean abundance of copepods in each group identified through in-cluster analysis of the copepod community (see Figure 4a) peaked at 500 to 2,000 m (Figure 3b). Increases in the number of species and species diversity in the mesopelagic zone (200 to 1,000 m) and bathypelagic zone (1,000 to 3,000 m) have been reported in the North Atlantic (Roe 1972), the Mediterranean Sea (Scotto di Calro et al 1984), the western North Pacific (Yamaguchi et al 2002), and the Bering Sea (Homma and Yamaguchi 2010). This suggests that an increase in the number of calanoid copepod species in the meso-and bathypelagic zones is a common phenomenon of the ocean worldwide.…”

“…Vinogradov 1968). Examples include studies in the Arctic Ocean (Kosobokova and Hirche 2000;Auel and Hagen 2002), Greenland Sea (Richter 1994), Bering Sea (Homma and Yamaguchi 2010), Atlantic Ocean (Roe 1972;Koppelmann and Weikert 1999), subarctic Pacific (Vinogradov 1962;Arashkevich 1972;Yamaguchi et al 2002;Steinberg et al 2008), Mediterranean Sea (Scotto di Calro et al 1984;Weikert and Trinkaus 1990;Koppelmann and Weikert 2007), Arabian Sea (Madhupratap and Haridas 1990;Fabian et al 2005;Koppelmann and Weikert 2005;Wishner et al 2008), Red Sea (Weikert 1982;Weikert and Koppelmann 1993), and the Antarctic Ocean (Schnack-Schiel et al 2008). Most of these studies examined biomass, which is easy to measure, but few have identified and evaluated specimens down to species level.…”