Near-bottom zooplankton over three seamounts in the east Canary Islands: Influence of environmental variables on distribution and composition.

Abstract

The near-bottom zooplankton over three seamounts of the eastern Canary Islands (Amanay, El Banquete and Concepción) was analyzed, identifying the environmental variables that explain biomass distributions over them. Zooplankton composition changed between adjacent water masses, except for the two deepest assemblages associated with Atlantic Antarctic Intermediate Water (AAIW) and Mediterranean Water (MW). The highest biomass of total zooplankton and of main taxa (e.g. copepods, chaetognaths, siphonophores) were recorded at the seamount summits, i.e., over Amanay-El Banquete (summit depths of 23-24 m) associated with Surface Water (SF) and over Concepción (150 m) in upper levels of the North Atlantic Central Water (NACW). Biomass minima at the three banks were found at ca. 250-650 m, in the deepest levels of NACW. At ca. 700-1000 m (the level occupied by AAIW) and below 1000 m (MW level) biomass increased again. Near-bottom fluorometry (f 5mab , 5 m above bottom) and dissolved oxygen (O 2 5mab) were the main variables explaining changes of total zooplankton/main taxa biomass. Biomass minima (250-650 m) coincided with decreases of O 2 5mab (3.30-3.99 ml/l at 400-700 m) at deepest depths occupied by NACW. Other variables not included in our models like turbidity (resuspension of particles) may have locally enhanced zooplankton aggregation, as they may locally occur alongside Concepcion at the NACW-AAIW confluence (at ca. 700 m), probably from the effects of internal waves. Our results suggest that observations regarding the attraction of organisms to the stationary substrates of seamounts could be related to elevated chlorophyll fluorescence and O 2 5mab concentration. Peaks in those variables apparently enhance zooplankton aggregation.

Composition and distribution of the larval decapod community in the deep sea of the Western Mediterranean Sea Balearic Sub‐basin

“…The BBL, basically an ecotone between the pelagic and benthic system, seems to be a good habitat for advanced stages of decapod larvae. The BBL may play an important role in fauna dynamics due to the resuspension of particles (near‐bottom turbidity) associated with this level (Cartes, Lolacono, et al., 2013; Papiol et al., 2019), important for suprabenthic fauna (Mees & Jones, 1997).…”

“…Suspended particulate organic matter (POM) may constitute an attractive food source for shrimp (Caridea and Dendrobranchiata), which were more abundant not immediately on the bottom or in the water column off the seabed, but at 1–25 m above it. Dissolved oxygen is another factor influencing zooplankton density (Cartes, Fanelli, et al, 2013; Cartes, Lolacono et al., 2013; Papiol et al., 2019), but in this case the density of Sergestidae , which increased during stratification period (CCA‐GAM results).…”

Challenges and Advances in the Taxonomy of Deep-Sea Peracarida: From Traditional to Modern Methods

“…Manned submersibles or remotely operated vehicles (ROV) can help in the sample collection by means of push-corer, suction pump, small nets or picking up larger structures on hard substrata (for sampling specificities see Jamieson, 2016;Kaiser and Brenke, 2016;Kelley et al, 2016;Narayanaswamy et al, 2016;Frutos et al, 2017a). In water column studies, pelagic peracarid species are collected by means of mid-water trawls or plankton nets (Kürten et al, 2013;MacIsaac et al, 2014;Papiol et al, 2019); the latter are also suitable as collector of benthic peracarids if they are used as additional sampler attached to trawling devices such as otter or beam trawls (Nouvel and Lagardère, 1976;Lagardère, 1977). In addition, peracarids can also be sampled indirectly by examining the gut content of decapod or the fish stomach content, because they are their food source (Sorbe, 1981;Carrasón and Matallanas, 2001;Preciado et al, 2017).…”

Exploring the origin and fate of surface and sub-surface marine microplastics in the Canary Islands region

“…The southern direction is favored by the presence of mesoscale Mediterranean water eddies ("meddies") activity (Richardson et al, 2000;Bower et al, 2002), which are wellknown structures of accumulation and conservation of water properties (Sangrà et al, 2009). Some of these meddies regularly reach the Canary Islands latitudes where their presence has been registered over several decades influencing the water characteristics at intermediate levels (Machıń et al, 2006;Papiol et al, 2019).…”