The spring mesozooplankton variability and its relationship with hydrobiological structure over year-to-year changes (2003–2013) in the southern Bay of Biscay (Northeast Atlantic)

Abstract

Mesozooplankton can be considered the most important secondary producers in marine food webs because they hold an intermediate position between the phytoplankton assemblage and the upper trophic levels. They also are a robust indicator of climatic and hydrological conditions. We conducted an analysis of the interannual variability of the spring mesozooplankton assemblage, as sampled by the PELGAS fisheries survey in the southern part of the Bay of Biscay (Northeast Atlantic Ocean) between 2003 and 2013. We examined hydrology and trophic drivers to explain the variability. Our results revealed that the subsurface temperature, the subsurface salinity, the biomasses of subsurface pico-, nano-, and microphytoplankton, and the copepod assemblage exhibited a recurrent spatial pattern that was driven mainly by freshwater and nutrient inputs from the main rivers. The mesozooplankton assemblage was dominated by copepods (82%), composed of coastal, neritic, and oceanic copepod genera that paralleled the various hydrological fronts converging in the southern Bay of Biscay. The copepod community displayed high temporal-variability; there were three periods of abundant adult copepods throughout the southern Bay of Biscay. The copepod community was structured primarily around the drive for resource control, especially by the microphytoplankton biomass (24.3% of the total variability), and to a lesser extent by hydrological features (13.7% of the total variability). Highlights ► Spring mesozooplankton was studied over a decade in the southern Bay of Biscay. ► Hydrobiological features of habitats displayed relatively stable spatial patterns. ► Spatial structuration of habitats was mainly driven by continental outflow. ► Mesozooplankton abundance decreased from 2007 to 2009 but recovered afterward. ► High percentage of gelatinous organisms and low percentage of copepods occurred in 2006. ► In springtime, the copepod dynamics was mainly governed by resource availability.

Primary production and depth drive different trophic structure and functioning of fish assemblages in French marine ecosystems

“…The predominance of zooplankton feeding species is also classical in the Gulf of Lions. Low energy densities recorded for zooplankton, notably when compared with counterparts in the Bay of Biscay (Chen et al, 2019;Dessier et al, 2018), also confirms that the basal energy is too low to support losses linked with energy dissipation at several trophic levels (Bănaru et al, 2013(Bănaru et al, , 2019.…”

“…Values measured for small zooplanktonic groups (calanoids, Oithona, Oncaea and Temora) were used as proxies of pelagic production, as these groups dominate the pelagic environment and pelagic fish diet (Chouvelon et al, 2015;Dessier et al, 2018). In the Gulf of Lions, prickly cockle Acanthocardia echinata individuals were sampled during MEDITS and analyzed simultaneously with fish, whereas data for the 200-300 µm zooplankton size class was used as a proxy of pelagic production (D. Bănaru, unpubl.…”

Major changes in sardine growth and body condition in the Bay of Biscay between 2003 and 2016: Temporal trends and drivers

“…Such a result could therefore suggest that despite a high level of Chl-a, other factors such as zooplankton quality and quantity may negatively impact body condition and growth, leading to their decrease. Analyzing temporal trends in the mesozooplankton and copepod communities Dessier et al (2018) highlighted three temporal phases of adult copepod dominance. The periods 2003-2006 and 2010-2013 were characterized by higher abundance values in copepods than the mean decadal abundance in spring, while a lower abundance was found during the period 2007-2009.…”

Antxoaren maneiu eta kontserbazioa: biomasan eragiten duten faktoreen azterketa

“…Beraz, harrapari horien ugaritzeak zooplanktonaren ugaritasuna murrizten du [34]. Bizkaiko Golkoan 2006ko udaberrian zegoen kopepodo proportzio baxua, esaterako, organismo gelatinakaren (knidario eta sifonoforoak batik bat) proportzio altuarekin erlazionaturik dago [35].…”

“…Horrela, antxoak eskuratzen duen energiaren murriztapen horrek indibiduoak muskuluaren aktibitatera bideratuko duen energia gutxituko du. Hala, haren igeriketa efizientzia murriztuko da, besterik ezean; antxoa gazteak (baita helduak ere) gosez hil daitezke behar adina harrapakin ez aurkitzeagatik, batik bat negu bukaeran [34,35,57]. Era berean, indibiduo ahulenak harraparien harrapakin izango dira [71].…”