Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study of Acartia, Temora and Eurytemora species in the south-west Baltic

Information on physiological rates and tolerances helps one gain a cause-and-effect understanding of the role that some environmental (bottom–up) factors play in regulating the seasonality and productivity of key species. We combined the results of laboratory experiments on reproductive success and field time series data on adult abundance to explore factors controlling the seasonality of Acartia spp., Eurytemora affinis and Temora longicornis, key copepods of brackish, coastal and temperate environments. Patterns in laboratory and field data were discussed using a metabolic framework that included the effects of ‘controlling’, ‘masking’ and ‘directive’ environmental factors. Over a 5-year period, changes in adult abundance within two south-west Baltic field sites (Kiel Fjord Pier, 54°19′89N, 10°09′06E, 12–21 psu, and North/Baltic Sea Canal NOK, 54°20′45N, 9°57′02E, 4–10 psu) were evaluated with respect to changes in temperature, salinity, day length and chlorophyll a concentration. Acartia spp. dominated the copepod assemblage at both sites (up to 16,764 and 21,771 females m−3 at NOK and Pier) and was 4 to 10 times more abundant than E. affinis (to 2,939 m−3 at NOK) and T. longicornis (to 1,959 m−3 at Pier), respectively. Species-specific salinity tolerance explains differences in adult abundance between sampling sites whereas phenological differences among species are best explained by the influence of species-specific thermal windows and prey requirements supporting survival and egg production. Multiple intrinsic and extrinsic (environmental) factors influence the production of different egg types (normal and resting), regulate life-history strategies and influence match–mismatch dynamics

Environmental control of mesozooplankton community structure in the Seine estuary (English Channel)

This paper is the first to describe the spatio-temporal changes of mesozooplankton in the Seine estuary. Monthly samples were collected along the estuary in 1996 in order to analyse the seasonal changes of the mesozooplankton community and to identify the major environmental parameters that may influence the spatial distribution of zooplankton in this megatidal estuary. Statistical analysis (canonical correspondence analysis) showed that salinity was the main factor correlated with the longitudinal distribution of zooplankton. Marine species (Temora longicornis, barnacle larvae...) were located in the outer part of the estuary, while more oligohaline species (Eurytemora affinis) were recorded in the inner part of the estuary. A mixed zone was characterised by the presence of the neritic copepods Acartia spp. and Eurytemora affinis. The marine species (e.g. T longicornis, Oikopleura dioica, Barnacle larvae) showed maximum abundance at the end of spring (June) while the most abundant estuarine species, E. affinis, peaked in late winter-spring and declined with the onset of summer. This copepod dominated the estuarine zooplankton throughout the year, and found in the Seine estuary very high favourable conditions to exhibit ultimate abundances (> 190 000 ind m(-3)) which is one order of magnitude higher than those found in other European estuaries. It represented the main prey for major planktonivorous species such as suprabenthic and fish species located living in the upstream zone of the Seine estuary. (C) 2002 Ifremer/CNRS/IRD/Editions scientifiques et medicales Elsevier SAS. All rights reserved.Des prélèvements mensuels ont été réalisés en 1996 afin d’analyser les changements temporels de la communauté mésoplanctonique estuarienne et d’identifier les principaux paramètres responsables de la distribution spatiale du zooplancton dans cet estuaire mégatidal. Des analyses statistiques (analyse canonique des correspondances) ont montré que la salinité est le principal facteur contrôlant la distribution spatiale du zooplancton. Une zone intermédiaire comporte un assemblage faunistique composé d’espèces néritiques comme les copépodes du genre Acartia et le copépode oligohalin Eurytemora affinis. Les espèces marines (e.g. T. longicornis, Oikopleura dioica, larves de cirripèdes) atteignent leur maximum d’abondance à la fin du printemps (juin) alors que le copépode prépondérant dans l’estuaire, E. affinis, a un maximum à la fin de l’hiver et au début du printemps. Son abondance commence à décliner dès l’été. Cependant, ce copépode domine la communauté mésozooplanctonique estuarienne toute l’année et trouve, dans l’estuaire de la Seine, des conditions de développement très favorables puisque les densités maximales dépassent 190 000 ind m–3, soit un ordre de grandeur plus élevé que dans les autres grands estuaires européens. Il est la proie favorite de nombreuses espèces planctonophages et suprabenthiques ainsi que des poissons fréquentant cette partie amont de l’estuaire de la Seine

Zooplankton distribution and dynamics in a temperate shallow estuary

Abstract The spatial, temporal and tidal dynamics of the zooplanktonic community of the Mondego estuary was studied from January 2003 to 2004. The monthly sampling procedure included the measurement of hydrological parameters (salinity, temperature, Secchi transparency, chlorophyll a and nutrients) and the collection of zooplankton with a Bongo net of 335 µm mesh size. Zooplankton composition, distribution, density, biomass and diversity were determined. The principal component analysis (PCA) revealed the existence of a spatial gradient with the upstream sampling stations, associated to high values of nutrients, in opposition to the downstream stations characterized by higher salinity and transparency values. The Copepoda was the main dominant group and Acartia tonsa revealed to be the more abundant taxon. The spatial and temporal dynamics of zooplanktonic communities analysed by non-metric MDS showed the existence of four assemblages of species-sites, reflecting differences in zooplankton composition between both branches of the estuary. The results suggest that abundance, biomass and diversity of the zooplanktonic community are strongly influenced by the hydrological circulation pattern and by direct or indirect human impacts that occur in each branch. The northern branch is dominated by the river flow suffering from regular dredging activities and the southern branch is dominated by tidal circulation suffering from an ongoing eutrophication process

Mesozooplankton structure and seasonal dynamics in three coastal systems of Argentina: Bahía Blanca Estuary, Nuevo Gulf and Ushuaia Bay

Mesozooplankton communities in coastal ecosystems have successfully adapted to a wide range of environments. However, the current rate of coastal modification is challenging the survival of resident species. In this chapter, we describe the structure and annual dynamics of the mesozooplankton community in recent years for three coastal systems in Argentina that are subject to human disturbance: (1) Bahía Blanca Estuary, (2) Pirámide Bay in Nuevo Gulf and (3) Ushuaia Bay in the Beagle Channel. The seasonal dynamics of mesozooplankton abundance in Bahía Blanca Estuary during 2009-2010 exhibited a unimodal pattern with an increase during the warm seasons, while organism abundance increased linearly with both salinity and turbidity. In Nuevo Gulf, research on the seasonal dynamics of mesozooplankton conducted during 2014-2015 exhibited a bimodal abundance pattern with peaks in late summer and spring. No significant relationships between mesozooplankton and the environmental variables included in Nuevo Gulf were found. The seasonal dynamics of mesozooplankton in Ushuaia Bay in the years 2006-2008 exhibited a bimodal abundance pattern with peaks in summer and early autumn; this pattern was mainly driven by the concentration of chlorophyll a. In Bahía Blanca Estuary, a gradual decrease in species richness was observed throughout the last four decades, while changes in species composition were also observed, suggesting that some species have the ability to acclimate to higher salinity and turbidity as well as to pollution. In Nuevo Gulf, the mesozooplankton community showed no significant modifications over time, which may be related to the low anthropogenic pressure. Although no profound shifts in mesozooplankton were observed in Ushuaia Bay, eutrophication may have an impact in the future through its effect on primary producers.Fil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: López Abbate, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: D'agostino, Valeria Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Presta, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Uibrig, Román Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: García, Tami Mailén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Nahuelhual, Eugenia Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Chazarreta, Carlo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Garcia, Maximiliano Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Capitanio, Fabiana Lia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin