Local changes in copepod composition and diversity in two coastal systems of Western Europe

Abstract

While long-term monitoring is essential to improve our knowledge of marine ecosystems health, 37 it remains challenging to summarise complex ecological data in order to characterise and understand 38 biodiversity trends. To compile monitoring data across large numbers of species, scientists and policymakers mainly rely on diversity and species richness indices. This task may prove complicated 40 however, as many indices exist and no individual metric undoubtedly emerges as the best overall. Here, 41 using data from zooplankton surveys from 1998 to 2014, we examined year-to-year changes in copepod 42 communities in two littoral ecosystems of Western Europe-the Arcachon Bay and the Gironde estuary 43-that share similar climate, but with different local ecological processes, especially hydrological 44 conditions. We tested the ability of commonly used α and ß-diversity metrics, such as species richness, 45 Pielou's evenness or Jaccard's index, to mirror year-to-year changes in species abundances and we 46 detected a synchronous change in both copepod abundances and α-diversity that took place circa 2005 47 in the two sites. In response to changes in environmental conditions such as nutrients, salinity, river 48 discharge or particulate matter, two opposite biodiversity trends were observed, with a decrease in 49 copepod diversity in the Arcachon Bay but an increase in the downstream part of the Gironde estuary. 50 Although diversity metrics allowed us to well detect trends, the use of multivariate approaches such as 51 principal component analysis provided important information on how and why diversity fluctuates. Our 52 study provides evidence that long-term monitoring programmes must be encouraged for optimising 53 management and conservation actions such as the Marine Strategy Framework Directive and that more 54 local comparative studies need to be initiated for better characterising diversity trajectories at very fine 55 scales at which ecologists often work.

Bi-decadal variability in physico-biogeochemical characteristics of temperate coastal ecosystems: from large-scale to local drivers

“…In other lowsalinity ecosystems, especially in wetlands and lagoons, an increase in salinity can lead to a decrease in zooplankton abundance and a reduction in species richness (Schallenberg et al 2003). Richirt et al (2019) showed that changes in copepod abundance in the Arcachon Lagoon, one of the studied ecosystem, are governed by changes in physico-biogeochemical parameters, including salinity and SPM.…”

WGEUROBUS – Working Group “Towards a EURopean OBservatory of the non-indigenous calanoid copepod Pseudodiaptomus marinUS”

“…The first appearance of P. marinus was in the southern sector of the Bay of Biscay and dates back to 2010 in the estuary of Bilbao (Albaina et al 2016;Uriarte et al 2016), followed by occurrence in the Gironde Estuary (Brylinski et al 2012;Richirt et al 2019), and since 2016 in the Guadalquivir Estuary (Reyes-Martı ´nez and Gonza ´lez-Gordillo 2019) (Fig. 3, LD).…”

“…Over the last decade, Pseudodiaptomus marinus has been increasingly recorded in European waters: Mediterranean Sea (de Olazabal and Tirelli 2011; Delpy et al 2012; Erdog ˘an and Ertan 2014; Karuza Luc ˇic ´et al 2015;Pansera et al 2014;Sabia et al 2015;Stefanni et al 2018;Vidjak et al 2019;Zagami and Brugnano 2013), Black Sea (Garbazey et al 2016), European Atlantic coasts (Brylinski et al 2012;Reyes-Martı ´nez and Gonza ´lez-Gordillo 2019;Richirt et al 2019;Uriarte et al 2016), and Southern North Sea (Deschutter et al 2018;Gu ¨nther et al 2018;Jha et al 2013;Wootton et al 2018). In November 2017, P. marinus was also found in three coastal sites in the Gulf of Gabe ´s (Tunisia) (33.90°N, 10.20°E) (N. Makhlouf, M. Nejib Daly Yahia and M. Pagano, pers.…”

“…The majority of main ports (Rotterdam, Antwerp, Amsterdam, Bremerhaven, London, and Immingham) are located in the Southern sector of the North Sea and are typically accessed via a route through the English Channel (Nilsson et al 2018). The first observations of P. marinus in the region were : Gravelines (Brylinski et al 2012); : Calais (Brylinski et al 2012); : Gironde Estuary (Brylinski et al 2012;Richirt et al 2019); : Estuary of Bilbao (Albaina et al 2016;Uriarte et al 2016); : Guadalquivir Estuary (Reyes-Martı ´nez and Gonza ´lez-Gordillo 2019); : Berre Lagoon (Delpy et al 2012); : Marina di Carrara (Sabia et al 2015); : Lake Fusaro (Sabia et al 2015); : Gulf of Naples (multiple sites) (Sabia et al 2015); : Lake Faro and Lake Ganzirri (Pansera et al 2014;Sabia et al 2015;Zagami and Brugnano 2013); : Mar Piccolo of Taranto (Karuza et al 2016 made from samples taken in Calais harbour and in Gravelines (France) in 2010 (Brylinski et al 2012), followed by further records in Southern North Sea (Deschutter et al 2018;Gu ¨nther et al 2018;Jha et al 2013;Wootton et al 2018) (Fig. 3, LD).…”

Seasonal Variations in the Biodiversity, Ecological Strategy, and Specialization of Diatoms and Copepods in a Coastal System With Phaeocystis Blooms: The Key Role of Trait Trade-Offs

“…For a comprehensive assessment of environmental gradients, the calculation was, therefore, based on the ecological specialization of long-term diatom and copepods datasets, collected between 1996 and 2019 at the station "C, " and from 2001 to 2017, respectively, in the downstream part of the Gironde estuary (Breton et al, 2000;Schapira et al, 2008;Breton et al, 2017;Richirt et al, 2019). Environmental tolerance was based on species biomass, considering: (i) SST, S, Pa, nutrients, and PAR for diatoms; and (ii) SST, S, Pa, TSM, and POC for copepods.…”