Temporal Variability of Abundance, Morphological and Reproductive Traits of the InvasiveArctodiaptomus dorsalis (Copepoda: Calanoida: Diaptomidae) in Relation to the Reduction of Aquaculture in Lake Taal (2008 & 2013)
Justine R. de Leon1, Henberson G. de Vera1, Earvin Justin A. Giron1, Hazel Joyce A. Guerrero1, Sophie Chambord3, Anissa Souissi3, Sami Souissi3, and Rey Donne S. Papa1,2
1Department of Biological Sciences, College of Science,
University of Santo Tomas, Manila, Philippines
2Research Center for the Natural and Applied Sciences and the Graduate School,
University of Santo Tomas, Manila, Philippines
3Université Lille1 – Sciences et Technologies,
Laboratoire d’Océanologie et de Géosciences – UMR LOG 8187, Wimereux, France
corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.; This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Calanoid copepods are the dominant zooplankton group of pelagic ecosystems and act as an intermediary between producers and higher level consumers. The abundance of copepods can be an indicator of favorable conditions in an aquatic environment. Arctodiaptomus dorsalis is an invasive calanoid species that thrives in many eutrophic lakes in the Philippines. This study aims to determine the differences between the morphometrics, abundance, and reproductive traits of A. dorsalis samples from 2008 and 2013 and if these changes were influenced by environmental factors in Lake Taal. Morphometric analysis and abundance were compared between samples collected in 2008 and 2013. Similar temporal trends in abundance were observed for both years. However, the abundance decreased in the 2013 samples except for the mature male A. dorsalis. Morphometric measurements showed that total length and total width were larger in 2013 compared to 2008. Reproductive traits such as egg size and clutch size did not vary between years. Secondary data on physico-chemical variables obtained from the Bureau of Fisheries and Aquatic Resources (BFAR) and the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) did not vary between the 2 years as well. The data seems to indicate that the reduction of aquaculture and the prevailing water quality in Lake Taal did not directly affect the increased body size of A. dorsalis in 2013. The results propose that the increase in body size and lower populations of A. dorsalis may have been affected by factors such as fish predation and the trophic status of the lake.
INTRODUCTION
Taal (13°53’00”N - 120°56’00”E) is considered the third largest lake in the country and is classified as a caldera lake. It has a 682.8-km2 catchment area and drains via the Pansipit River to Balayan Bay in the southwest (Papa et al. 2008; Perez et al. 2008). . . . . . read more
