Short-term meso-scale variability of mesozooplankton communities in a coastal upwelling system (NW Spain)

Abstract

The short-term, meso-scale variability of the mesozooplankton community present in the coastal upwelling system of the Ría de Vigo (NW Spain) has been analysed. Three well-defined communities were identified: coastal, frontal and oceanic, according to their holoplankton-meroplankton ratio, richness, and total abundance. These communities changed from summer to autumn due to a shift from downwelling to upwelling-favourable conditions coupled with taxa dependent changes in life strategies. Relationships between the resemblance matrix of mesozooplankton and the resemblance matrices of meteorologic, hydrographic and community-derived biotic variables were determined with distance-based linear models (DistLM, 18 variables), showing an increasing amount of explained variability of 6%, 16.1% and 54.5%, respectively. A simplified model revealed that the variability found in the resemblance matrix of mesozooplankton was mainly described by the holoplankton-meroplankton ratio, the total abundance, the influence of lunar cycles, the upwelling index and the richness; altogether accounting for 64% of the total variability. The largest variability of the mesozooplankton resemblance matrix (39.6%) is accounted by the holoplanktonmeroplankton ratio, a simple index that describes appropriately the coastal-ocean gradient. The communities described herein kept their integrity in the studied upwelling and downwelling episodes in spite of the highly advective environment off the Ría de Vigo, presumably due to behavioural changes in the vertical position of the zooplankton.

Biogeographic and trophic drivers of mesozooplankton distribution on the northeast continental shelf and in Hauraki Gulf, New Zealand

“…However, this transitional region also sustained its own characteristic community, including high abundances of small copepods (Acartia sp., calanoid nauplii [Hall et al 2006] and copepodites, and Temora turbinata) and high densities of amphipod larvae, euphausiids (N. australis) juveniles and appendicularians (Oikopleura sp.). This was similar to the observation by Roura et al (2013) in northwest Spain that their 'frontal' sites supported specific zooplankton communities that responded to local conditions. The inner and outer Hauraki Gulf supported an abundant and diverse neritic and transitional affiliated community, as previously identified by Jillett (1971).…”

“…While dominated by holoplankton, it also included meroplanktonic larvae (primarily of crabs, bivalves and barnacles), unlike the exclusively holoplanktonic outer shelf. This reflected the proximity of these larvae to their natal benthic populations (Roura et al 2013) and the influence of ontogeny in affecting mesozooplankton distributions. The shoreward increase in diversity from outer shelf to the outer and inner gulf sites was similar to that observed by Nogueira et al (2012) in northwest Spain, who attributed the greater diversity to heterogeneity of mesocale hydrographic structure in the coastal region.…”

“…These transfers are governed both by biogeographic factors driving the distributions of mesozooplankton species abundance and by the trophic relationships the species have within the food web. Biogeographic factors include water mass fronts at shelf breaks (Mackas & Coyle 2005), at upwelling zones (Simard et al 1986;Resgalla et al 2001;Escribano et al 2012), and between shelf and neritic waters (Jillett 1969;Willis et al 2006;Nogueira et al 2012;Roura et al 2013). Trophic factors are driven by seasonality of temperature, light and nutrient supply that control lower food web structure (Chisholm 1992;Smith & Kemp 2001), affecting mesozooplankton taxon succession and interactions with the food web (Wassman 1998).…”

Anisakis simplexcomplex (Nematoda: Anisakidae) in zooplankton communities from temperate NE Atlantic waters

“…These samples belonged to communities which have recently been described in the Ría de Vigo by Roura et al (2013). These authors defined six characteristic mesozooplankton communities during the upwelling season correlated with the bathymetric gradient, in early summer and in autumn.…”

“…Mesozooplankton organisms were counted and identified to the lowest taxonomic level, as described in Roura et al (2013). Species diversity was calculated using the Shannon-Wiener Index (Omori and Ikeda 1984).…”