No abstract

Zooplankton were collected from LakeTaal between January and December 2008 in order to test for differences in species composition and abundance between a lake basin with intensive fish cage (FC) aquaculture and an open water area without FCs. Most species showed similar patterns of occurrence in both basins while having differences in abundance. Several rotifer species were more abundant in FC sites most of the year, while for microcrustaceans higher abundances in FC sites only happened during the first 2 months. Their distribution is attributed to the presence of higher nutrient levels in FC sites as well as wind-induced basin-wide water movements during the different monsoon seasons which disperse plankton and nutrients from FC sites to other parts of the lake. Zooplanktonic indicators, (QBrr) and the ratio. of calanoids to c1adocerans and cyclopoids, clearly demonstrate the eutrophic state of the lake. A comparison with previous studies suggests that the lake was already eutrophic prior to the introduction of aquaculture in the 1970s. The trophic conditions in Lake Taal may be attributed to the lakes' tropical and volcanic nature, with productivity further enhanced by increased nutrient input from aquaculture.

The Mananga River today is a source of potable water to meet the demands of a fast growing Cebu metropolis. The physicochemical parameters of Mananga River were studied to assess its water quality status. Six sample collections were done from February to December 2006 in 3 monitoring stations covering the upstream (S1), midstream (S2) and downstream (S3) of Mananga River. Results showed significant spatial variation (p<0.05) in the studied physicochemical parameters except for alkalinity, total phosphates and nitrate-nitrogen (NO3-N). Significant temporal variation (p<0.05) was also observed for the factors except for stream width, biological oxygen demand (BOD5) and total suspended solids (TSS). Flow velocity showed significant positive correlation with discharge, pH, DO and NO3-N, and negative correlation with water temperature and TSS. Water temperature correlated negatively with DO and pH, and positively with TSS, with the latter showing a positive correlation with BOD5. The results implied that water currents play a major role in the distribution of dissolved substances and the suspension of sediments. Water quality of the studied segments of Mananga River progressively decreased downstream and was more pronounced during the dry periods. Results also indicated that the river was receiving loads of organic matter from natural and anthropogenic sources.   Keywords - ecology, Mananga River, water quality, flow velocity, Cebu City, Philippines

Abstract. Napaldet JT, Buot Jr. IE, Zafaralla MT, Lit Jr. IL, Sotto RC. 2019. Effect of phytoremediation on the morpho-anatomical characters of some aquatic macrophytes. Biodiversitas 20: 1289-1302. In constructed wetland studies, the effect of pollutants or the phytoremediation set-up on aquatic macrophytes is often not investigated. This literature gap may prove useful in realizing the full phytoremediation potential of aquatic macrophytes. This study was conducted to examine the effect of phytoremediation, the set-up, and the pollutants, on the morpho-anatomical characters of aquatic macrophytes used in the constructed wetlands. This was investigated in Amaranthus spinosus, Eichhornia crassipes, Eleusine indica, and Pennisetum purpureum. Simultaneously, interesting anatomical features in the aquatic macrophytes were discovered. Anomalous secondary growth was discovered in roots and stems of A. spinosus while isobilateral anatomy of the leaf with two layers of vascular bundles and two palisade layers under each epidermis were noted in E. crassipes. The anatomy of P. purpureum was also first reported here. Results showed that the response of the aquatic macrophytes toward phytoremediation treatments was species-specific. E. indica and P. purpureum were the ones significantly affected by the phytoremediation treatment in contrasting ways. E. indica under phytoremediation suffered significantly lower growth rate than those in the uncontaminated site which could be attributed to the inability of its relatively short root system to tap into the water and nutrients. On the other hand, P. purpureum exhibited higher biomass and growth rate under phytoremediation treatment which is primarily due to the water pollutants absorbed as nutrients by the plant. There were no structural differences observed in the anatomy of the aquatic macrophytes between sampling sites except in E. indica. The root’s cortex in samples under phytoremediation has no aerenchyma while this is present in uncontaminated site and Balili River samples. This shows that, indeed, some aquatic macrophytes were significantly affected (p=0.00) by phytoremediation that should be taken in consideration when planning and designing constructed wetlands.

Contamination of lead in fishes from Laguna de Bay was previously recorded to have the highest concentrations that may pose a hazard to human health. However, no previous study was conducted on its biomagnification. This research is the first exploratory study that examined lead biomagnification in a food web of the lake. Water quality, aquatic communities, trophic levels and lead concentrations were analyzed during the dry and wet seasons. Lead concentrations were analyzed using Atomic Absorption Spectrometry. Levels of lead in the water were 0.05 mg L-1 and 0.03 mg L-1for dry and wet seasons, respectively. Lead concentrations increased in phytoplankton with 3.87 and 9.66 mg kg-1 lead during wet and dry season, respectively. Furthermore, lead levels increased in zooplankton with 2.92 and 14.31 mg kg-1 during wet and dry seasons, respectively. In fishes, the highest lead concentration in dry season was detected in Hypophthalmichthys nobilis with 0.38 mg kg-1 while the highest during wet season was observed in Oreochromis niloticus with 0.67 mg kg-1. Lead biomagnification was observed in this study in the following order: water < phytoplankton < zooplankton. However, this increasing trend did not continue up to fishes.