Banca de QUALIFICAÇÃO: ANA KAROLINA DOS SANTOS SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : ANA KAROLINA DOS SANTOS SILVA
DATE: 24/11/2025
TIME: 09:00
LOCAL: SALA DE REUNIÕES DO DECOL/CB/UFRN
TITLE:

Interaction Between Zooplankton and Phytoplankton in a Tropical Reservoir During Extreme Hydrological Events

KEY WORDS:

Trophic interactions; Time series; Semi-arid region; Extreme drought; Shallow lakes.

PAGES: 40
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Quantifying the zooplankton:phytoplankton ratio can provide insights into the sensitivity of zooplankton (consumers) to changes in phytoplankton (producers) under varying environmental conditions. One metric used to assess this interaction is the biomass ratio between these communities (Zoo:Phyto). This study evaluated the zooplankton:phytoplankton interaction over a 13-year period in a reservoir subjected to extreme hydrological events (heavy rainfall and severe drought). Phytoplankton and zooplankton were sampled quarterly from 2010 to 2022 in the Gargalheiras Reservoir (RN), located in the semi-arid region of Brazil. Zooplankton were grouped according to feeding strategy and body size, and the timeline was divided into three distinct periods: wet (2011–2012; 2022), dry (2015–2018), and transitional (2013; 2014; 2019). Principal Component Analysis (PCA) revealed an environmental gradient: the wet period was associated with higher water volume and dissolved oxygen, while the dry period showed elevated total phosphorus concentrations and lower Secchi transparency. The Zoo:Phyto ratio did not change significantly over time (p > 0.05) or between hydrological periods, although a temporary increase was observed during the extreme drought, coinciding with the dominance of raptorial copepods and potentially mixotrophic nano-phytoplankton. Zooplankton community structure based on functional groups varied across periods (PERMANOVA: Pseudo-F = 2.22; r² = 0.10, p = 0.005): filtering copepods were more associated with the wet period (r² = 0.20; p = 0.013), while large raptorial copepods dominated during the extreme drought (r² = 0.30; p = 0.009). Phytoplankton biomass also differed: Euglenophytes (r² = 0.24; p = 0.001) and Cryptophytes (r² = 0.23; p = 0.005) prevailed during the extreme drought, whereas cyanobacteria dominated in the wet and transitional periods (r² = 0.18; p = 0.007). These findings suggest that extreme hydrological events, in semi-arid, influenced the functional structure of planktonic communities, although they did not alter the overall consumer–producer ratio over time.

COMMITTEE MEMBERS:
Presidente - 2412921 - JULIANA DEO DIAS
Interna - 1764855 - VANESSA BECKER
Externa ao Programa - 1434166 - LUCIANA SILVA CARNEIRO - UFRN