Temperature as main driver of the growth of an endemic Philippine freshwater copepod (Copepoda: Calanoida: Diaptomidae)

Abstract

We conducted a preliminary analysis on the effects of various physical and chemical parameters on the morphometry and reproductive capacity of the calanoid copepod Filipinodiaptomus insulanus (Wright, 1928), endemic to the Philippines, by proxying clutch size (CS). Specimens and water quality readings were obtained between October 2019 and February 2020 from four sites in northern Philippines. Only the sizes of adult males and non-ovigerous adult females showed significant differences (P < 0.05) among populations. Non-eutrophic, temporary shallow waters were the predominant habitat type of F. insulanus, corroborating earlier observations that it is mainly found in relatively pristine environments. Correlation analysis showed a significant indirect relationship (P < 0.001) between the size of individuals and temperature, a potential adaptive response to its environment. Such observations may be valuable in preventing the disappearance of this species from parts of its previously known range.