Body size and its variability in the copepodAcartia margalefi(Calanoida) from Lake Acquatina (SE Italy)

Abstract

A long-term study on the body size of adult copepods was carried out on the Acartia margalefi population of Lake Acquatina in 1988-1991. Males were unusually longer than females independently from the season or the year. The specimens (both sexes) collected during cold months were longer than those collected during warm months. The body size of A. margalefi was strongly correlated with temperature. A correlation was found also with photoperiod, salinity and (but only for females) with adult sex-ratio and population density. The average body size of 1988-specimens proved statistically different from other years. Specimens collected from the lake were smaller than those from the sea, where in addition they did not show any sex size-dimorphism. These results suggest that the body size of A margalefi (a. species adapted to variable environments) is inversely correlated with favourable conditions for reproduction, and it shows a different variability range in the two sexes probably due to the different cost of gametogenesis in two sexes.

First report of the presence of Acartia bispinosa Carl, 1907 (Copepoda, Calanoida) in a semi-enclosed Bay (Sharm El-Maya), northern Red Sea with some notes on its seasonal variation in abundance and body size

“…The observed seasonal variability of the body size, seems to be inversely related to temperature, as confirmed by the Pearson correlation. Similar seasonal variability in size with a winter maximum are commonly observed in copepods (Deevey 1960, Uye et al 1982, Liang and Uye 1996, Belmonte and Cavallo 1997, Mauchline 1998, Riccardi and Mariotto 2000, Ara 2002, Gaudy and Verriopoulos 2004, Tellioglu 2006, Bozkurt and Can 2014). Among the other factors affecting copepod body size, food availability seems to be of great importance, at least in some ecosystems (Deevey 1960, Durbin et al 1983, Viitasalo et al 1995).…”

Factors affecting Oithona nana and Oithona similis along a salinity gradient

“…(Cepeda et al, 2015). As for other copepods, Belmonte and Cavallo (1997) found that the body size of female Acartia (Acartiura) margalefi Alcaraz, 1976 (a species adapted to variable environments) was strongly and inversely correlated with confinement. According to Uye (1994), the general shift to small-sized copepods in a progressive enhancement of confinement could be due to changes in the composition of food particles (replacement of diatoms by much smaller prey).…”

“…It is well known that plankton of confined environments is of smaller size than that of the open sea (Uye, 1994;Belmonte et al, 2013). Even the same species has a smaller body size in confined environments (Belmonte & Cavallo, 1997). This well-known result is generally correlated with salinity (lower salinity, smaller body size, and vice versa).…”

Coexistence of Two Copepods, Recorded for the First Time, in NW Iberian Shelf: The Case of Oithona atlantica and the Allochthonous O. davisae

“…If we observe its geographical distribution, O. atlantica could be considered a typical species of these waters. Furthermore, other studies [63] have shown that the copepod size composition can decrease with eutrophication and in confined coastal waters [64]. This fact could also explain the greater abundance of O. davisae in the inner part of the Ría de Arosa.…”