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Temporal and spatial zooplankton dynamics in a multistressor environment (Belgian part of the North Sea)
Rakotondrazafy, S.R.A. (2016). Temporal and spatial zooplankton dynamics in a multistressor environment (Belgian part of the North Sea). MSc Thesis. Oceans & Lakes, Interuniversity Master in Marine and Lacustrine Science and Management: Antwerpen, Gent and Brussel. 54 pp.

Thesis info:

Beschikbaar in  Auteur 
Documenttype: Doctoraat/Thesis/Eindwerk

Trefwoorden
    Aquatic communities > Plankton > Zooplankton
    Calanoida [WoRMS]; Copepoda [WoRMS]
    Marien
Author keywords
    Copepods; calanoids; temporal/seasonal and spatial dynamics; environmental stressors; Belgian part of the North Sea (BNPS)

Auteur  Top 
  • Rakotondrazafy, S.R.A.

Abstract
    Climate change, eutrophication and pollution are worldwide known to cause pressure on the marine environment. In the BNPS, earlier investigations have demonstrated seasonal and spatial changes in zooplankton density and distribution. Zooplankton communities are considered as good indicators of environmental stressors. However, the interactive and cumulative effects of physical and chemical factors on these organisms remain unclear. In this research, spatial and temporal dynamics of zooplankton communities in relation to environmental variables such as temperature, salinity, chlorophyll a, nutrients and toxicants were analyzed. Zooplankton samples were collected with a WP2 zooplankton net from winter to spring: February, April and May 2015 in the BNPS, along a nearshore-midshore axis with four selected stations. Environmental parameters, nutrient and Vessel (RV) Simon Stevin. The packages Primer v6, R and SPSS Statistics 23 were used for statistical analysis. This study revealed distinct spatial (nearshore and midshore) and temporal/seasonal variations both in the overall zooplankton and copepod communities. Zooplankton densities were often higher in the nearshore than in the midshore stations of the BNPS and increased from winter to spring. Zooplankton total densities differed significantly between stations (p= 0.001 and months (p= 0.001). Similarly, significant differences in total density between stations (p= 0.001) and months (p= 0.001) were found in the copepod community. The most abundant zooplankton groups in the BNPS were the copepods (Phylum Arthropoda) and the appendicularians (Phylum Chordata). The dominant copepods were the calanoids (order Calanoida) represented by Acartia clausi, Temora longicornis, Paracalanus parvus, Centropages hamatus, Pseudocalanus elongatus Calanus sp. and Centropages typicus. Acartia clausi and Temora longicornis were the most abundant calanoid species in the area. These seasonal and spatial variations were significantly related to temperature, salinity, chlorophyll a and PCB concentrations. Temperature was the variable which explained best density variations. The case study of Temora longicornis demonstrated environmental factors also influenced copepod body size. Mean prosome lengths of Temora longicornis were significantly correlated to temperature (p = 0.0001, r2 = 0.954), salinity (p= 0.0001, r2 = 0.851) and nutrient concentrations (p= 0.0001, r2 = - 0.686). Besides, significant correlations between densities of Temora longicornis and temperature (p= 0.0001, r2 = 0.786), PCB52 concentrations (p= 0.003, r2 = 0.496) and PAH concentrations (p= 0.006, r2 = 0.465) were found. This paper indicated temperature is the most important abiotic factor influencing zooplankton community structure. Cumulative and interactive effects of climate change with eutrophication and pollution on zooplankton community have been less examined so far and require special attention in the BNPS. Further investigations are needed to better understand the responses of zooplankton to multiple environmental stressors.

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