Factors influencing Diaptomus distributions: An experimental study in subtropical Florida1

Abstract

In central and southern Florida Diaptomus dorsalis is the sole diaptomid in most eutrophic lakes whereas Diaptomus floridanus and Diaptomus mississippiensis co‐occur in oligotrophic and mesotrophic lakes. The importance of food availability and water quality in determining the species distributions of Diaptomus was ascertained by culturing the three species in water from a lake of each type with its natural phytoplankton present and with the natural phytoplankton removed and Chlamydomonas added at a concentration above feeding saturation. The experimental evidence indicated that neither food availability nor water quality is important in excluding D. floridanus and D. mississippiensis from the eutrophic lakes. Additional data suggested that strong predation pressure may prevent these two species from occupying lakes of this type. However, low food availability seemed of major importance in excluding D. dorsalis from the oligotrophic and mesotrophic lakes. Competition is likely because food levels are always limiting and a potential competitor is present in the form of D. floridanus—in the same subgenus and close to the same size. Additional evidence suggests that predation is probably of lesser importance to the zooplankton in lakes of these types.

The effects of temperature and food on naupliar development, growth and metamorphosis in three species of Boeckella (Copepoda:Calanoida)

“…Elmore's slow developing small species and my fast developing large species are inconsistent with theoretical predictions concerning development times and body size (Hall et al, 1976) . The correlation between distribution of Diaptomus species and trophic level which Elmore (1983) found in his studies does not hold for Boeckella nauplii . For example, D. floridanus nauplii (a species inhabiting oligotrophic-mesotrophic lakes) developed faster than D. dorsalis (a species inhabiting eutrophic lakes) in an oligotrophic-mesotrophic treatment whereas D. dorsalis nauplii developed faster in eutrophic treatments .…”

“…In this experiment mortality was highest at colder temperatures (8 .5 and 12°C) and deaths mostly occurred among older naupliar stages . Elmore (1983) compared the development times, size and survival of three diaptomid species in a variety of food and temperature conditions . The survival and size data are only presented for complete development from egg to adult but development time data for nauplii are consistent with my observations .…”

The effects of temperature and food on copepodite development, growth and reproduction in three species of Boeckella (Copepoda; Calanoida)

“…Three authors to date have examined these effects: Vidal, 1980Vidal, , 1980aVidal, and 1980bWoodward andWhite, 1983 andElmore, 1983. Woodward and White worked on the same genus and found that Boeckella symmetrica copepodite development varied between 19.…”

Copepod post-embryonic durations: pattern, conformity, and predictability. The realities of isochronal and equiproportional development, and trends in the opepodid-naupliar duration ratio

“…1). The egg generally hatches as the first nauplius larva (Nl), and development proceeds through successive naupliar stages, maximally six in total (Nl-N6 Elmore, 1983Kamps, 1978Geiling & Campbell, 1972Munro, 1974Eckstein, 1964Weglenska, 1971 Jacobs (continued). the Dc/Dn ratio (see Table 1 for definitions and terminology) were included.…”