*Correspondence author: Claudia Padovesi-Fonseca, Departamento de Ecologia, Universidade de Brasília Group of Limnological Studies (NEL), Brazil
How to cite this article:Claudia Padovesi-Fonseca.Potential Use of Zooplankton as Ecological Quality Indicator According to Water Framework Directive (WFD) in Central Brazilian Reservoir. Oceanogr Fish Open Access J. 2020; 11(3): 555814.DOI: 10.19080/OFOAJ.2020.11.555814
Zooplankton species have high sensibility to environmental changes and impacts, leading to shifts in composition and diversity of the communities and associated to increase of biodiversity, with a high potential to endemism. With the implementation of the European Water Framework Directive (WFD), there was the ecological status classification of surface waters based on the assessment of series of biological quality elements (BQE) and supported by a set of chemical and hydro morphological quality data. Despite zooplankton have being considered a key component in pelagic food web, with a significant biological indicator of water quality, this group was not included at the first moment for the WFD evaluation. The ecological potential and the chemical status of an urban Brazilian reservoir (Lake Paranoá) during a eutrophic and restoration periods, represent a robust case study for the inclusion of zooplankton as a BQE in the WFD. This reservoir had a negative history on the water quality and for three decades (1968-1998) it was subjected to intense eutrophication. With the water quality restoration process and intentional flushing, changes in the plankton assemblages have been detected. During eutrophicated period, there were a dominance of detritivores microzooplankton and high biomass; and after recovery process, zooplankton biomass had a conspicuous decline accompanied to dominance of herbivorous larger bodies species. This study constitutes the first proposal to be done in central region of Brazil.
Keywords: Brazil Cerrado Aquatic biodiversity Water quality Lake restoration
Abbrevations: WFD: European Water Framework Directive; BQE: Biological Quality Elements.
The use of biological communities on ecosystems classification as well on monitoring program can intend to access their ecological assessment. It can be got to applying multimeric and predictive models [1-3]. Nowadays have been an increasing demand for effective monitoring methods based on biotic indices [4-6]. With the implementation of the European Water Framework Directive (WFD), there was the ecological status classification of surface waters based on the assessment of series of biological quality elements (BQE) and supported by a set of chemical and hydro morphological quality data . Various biological groups were included in the WFD analysis, such as phytoplankton, aquatic macrophytes macroinvertebrates and fishes [8-11]. Despite zooplankton have being considered a key component in pelagic
food web with a significant biological indicator of water quality this group was not included at the first moment for the WFD evaluation. Indeed, zooplankton species have high sensibility to environmental changes and impacts, leading to shifts in composition and diversity of the communities associated to increase of biodiversity, with a high potential to endemism [12-15]. Claimed for the inclusion of zooplankton as a BQE in the WFD because they could even the best quality indicators than other BQE .
Brazilian Central Plateau is covered by Cerrado. This neo-tropical savannah is recognized as a relevant world´s biodiversity hotspot, being biologically the richest one and with a highdegree of endemism, as review by . The central Brazilian
region is considered the “water cradle” of Brazil, with important
springs from South American watersheds. High biodiversity and
endemism associated with water human sources has made this
region an important area for the conservation with a further
sustainable human use. Anthropic activities have caused several
impacts on drainage-basins, as water pollution and silting of
running waters, affecting riparian and aquatic biota. More than
half of the vegetation cover of the Cerrado was replaced by
pastures and agriculture, in addition to urbanization .
Lake Paranoá (15º48’S, 47º47’W) is an urban reservoir, was
built in 1959 to provide recreation activities, power generation
and enhance the microclimate in Brazil’s Federal Capital, Brasilia.
It is situated in the Central Brazilian Plateau, at an altitude 1,000
m, with surface area 38 km2, volume 498.6*106 m3, max. depth
40 m, mean depth 13 m. The reservoir had a negative history
on the water quality and for three decades it was subjected to
intense eutrophication, culming to application of copper sulfate
to control cyanobacteria blooms . It was subjected to intense
eutrophication for 30 years 1968-1998), due mainly to human
occupation of the catchment area and nutrients inflow derived to
inadequate sewage treatment, especially since 1970’s .
For three decades, there were a dominance of detritivores
microzooplankton and a monoculture of filamentous blue greenalgae, Cylindrospermopsis raciborskii (Woloszynska) Seenayya
& Subba Raju, 1972 as well as blooms of Microcystis aeruginosa
(Kützing) Kützing, 1846 . Also, there were observed extended
areas of aquatic macrophytes (Eichhornia crassipes) and frequent
fish kills were observed during this period. Since 1993 nutrient
loading in Paranoá reservoir has been reduced, as a result of the
operation of a new sewage treatment system and a water quality
restoration process . Besides of this, there were no obvious
changes in the zooplankton community, and the predominance of
species usually related to eutrophicated systems .
After intentional flushing occurred in 1998, the reservoir had
a consequent water quality improvement . After this event,
changes in the plankton assemblages have been detected. In this
scenario of adjustments between environmental conservation and
human uses of water, it is necessary meets its goals to ensure the
availability of adequate water quality standards for current and
future generations and promote the rational and integrated use
of water resources. The flushing event produced a pronounced
and fast response of zooplankton assemblages. Zooplankton
biomass had a conspicuous decline accompanied to dominance
of herbivorous larger bodies species, as Calanoida and daphnids.
Temporal trends during the eutrophicated and after flushing
periods in Lake Paranoá were marked in relation to zooplankton
biomass and their groups (Figures 1 and 2).
In the Water Framework Directive (WFD), the European water
resources management system, the water quality is not linked to
the use, but to the ecological quality of the environment. The WFD
adopts ecosystem approach in order to the water bodies achieve
minimal degradation state. In ‘good conditions’, physical, chemical,
biological and hydro morphological conditions, the waterbodies
have ‘slight’ deviation from those without human action. For the
reservoirs, the WFD allows to identify and designate artificial and
heavily modified water bodies, and the goal is to achieve good
ecological potential and good chemical status for surface waters,
considering the objectives for the uses of these reservoirs
The use of aquatic biota constitutes the biological quality
element for the ecosystem evaluation as well as further monitoring
and generating new scenarios. The ecological potential and the
chemical status of an urban reservoir (Lake Paranoá) during an
eutrophic and recovery periods (after flushing event), taking into
account the basin uses and its occupation for each evaluated period
represent a robust case study for the inclusion of zooplankton as a
BQE in the WFD. In Brazil, there are few studies based on the WFD,
and this study constitute the first proposal to be done in central
region of Brazil. Zooplankton were not included as biological
quality element (BQE) in the implementation of WFD, although
zooplankton may be a cost-efficient indicator of the ecological
quality for reservoirs.
EC- European Commission (2012) Report from the Commission to the European Parlament and the Council on the Implementation of the Water Framework Directive (2000/ 60/EC). River Basin Management Plans. Brussels 15.