Spatial variability of zooplankton community structure in Colombian Caribbean waters during two seasons

Abstract

Zooplankton is an important component to understand oceanographic dynamics, they are considered good indicators of environmental variability, since most species are short-lived they can be tight coupling of climate and population dynamics, and some taxa are sensitive to variables such as temperature, quality and quantity of food, oxygenation and stratification. In the Colombian Caribbean two oceanographic cruises were carried out, in order to characterize and analyze the biodiversity of the continental margin, for the periods May-June 2008 and November-December 2009. The objective of this study was to determine which oceanographic variable was the most important in the distribution of zooplankton in the oceanic waters, and how the variables structure the community. In each cruise, zooplankton samples were obtained by vertical hauls with a 1 m2 diameter conical net (200 μm mesh size). The zooplankton community structure was studied by automated image analysis (ZooImage), which combined with abundance data, allowed to calculate the slope of size spectrum, and diversity indexes of taxa and sizes. The environmental variables included temperature, salinity, oxygen and chlorophyll a of the water column, and were used to calculate the stratification with the Brunt-Vaiisala frequency; this information was complemented by satellite images of temperature, surface chlorophyll, geostrophic currents and sea level, obtained from MODIS and AQUA products. The association between environmental variables and the zooplankton community structure was determined using Spearman’s correlation ranges with the Bioenv routine and a stepwise regression model, and Principal component analysis (PCA). Our results showed spatial and temporal patterns in the oceanographic conditions of the study area, such as upwelling in the Northeast region, strong stratification in the Southwest, and mesoscale activity. The abundance of zooplankton exhibited differences between the two climatic seasons and zones. Temporal differences were also evident in the size and diversity of taxa (ANOVA 2-way p <0.05). These changes were related to the moderate upwelling and the activity of mesoscale eddies. Cyclonic and anticyclonic eddies of variable size can either transport or retain zooplankton over cross-shelf and oceanic areas, thus modifying the taxonomic structure of the community. According to the Bioenv analysis, the main variables that explained the abundance and composition of zooplankton were sea level and chlorophyll a (Spearman correlation = 0.49). The stepwise regression showed that stratification, oxygen and chlorophyll a were the most important predictors of zooplankton abundance and size. Rev. Biol. Trop. 66(2): 688-708. Epub 2018 June 01.

Zooplankton Size Structure in Relation to Environmental Factors in the Xiangxi Bay of Three Gorges Reservoir, China

“…4). The is mainly because the upstream areas are vulnerable to hydrological disturbances and anthropogenic activities, which generally lead to a steeper NBSS slope (Dickerson et al 2010;Ma et al 2014;Medellin-Mora et al 2018). Comparing to García-Comas et al (2014), we found that the zooplankton size diversity in the Xiangxi Bay (mean value is 2.25) is slightly higher than that (mean value is 1.57) in the East China Sea.…”

Copepods of the off-shore waters of Caribbean Colombian Sea and their response to oceanographic regulators

“…We found low salinity values in surface waters of the central zone, showing the influence of waters of the Magdalena River in the oceanic zone, as well as sectors of high stratification. Low dissolved oxygen was recorded in this zone; values were lower at the surface (4 mg l −1 ) compared with other studies in oceanic waters of the Colombian Caribbean during the same period, which found values of 6–7 mg l −1 (Lozano-Duque et al ., 2010; Medellín-Mora et al ., 2018). A recent study reported values of 4.2 mg l −1 in the river, 6.9 mg l −1 in Bocas de Ceniza and 7.0 mg l −1 in the adjacent ocean (8 km from the mouth of river at 100 m depth) (Torregroza-Espinosa et al ., 2020).…”

“…The north-east oceanic stations showed low BVF (less stratification) and the deepest MLD in comparison to the central and south-west zones; these results agree with values previously recorded for the study period during the rainy season (Medellín-Mora et al ., 2018; Montoya-Sánchez et al ., 2018; Correa-Ramírez et al ., 2020) and are consistent with high values of geostrophic currents and deeper mixing layer in the offshore waters of the northern Colombian Caribbean Sea (Supplementary Figure S5). In the Caribbean Sea off Colombia the stratification (BVF) is dominated by salinity, which makes the water column highly stable to the depth of the subsurface salinity maximum (100–200 m), and mechanical mixing is the dominant process of salt diffusion from the SUW towards the surface (Correa-Ramírez et al ., 2020).…”

“…Studies conducted in oceanic waters of Colombia that also include deep-water ecosystems (mesopelagic and bathypelagic) beyond 500 m depth are scarce (Medellín-Mora & Martínez-Ramírez, 2010; Gutiérrez-Salcedo, 2011; Medellín-Mora et al ., 2018). These studies highlight the high abundance and diversity of the copepod assemblage, its vertical structure, trophic habits, and the close relationship of distribution and abundance with cyclonic and anticyclonic circulation patterns (Panama-Colombia Gyre and mesoscale structures) and water column structure.…”

“…It is called the Caribbean Current, which drifts towards the north-west sector; the Venezuelan basin communicates with the Colombian Basin through the Aruba Passage, with a threshold of 4000 m in the north-east zone (López & Mesa, 1984; Hernández-Guerra & Joyce, 2000; Ruiz-Ochoa, 2011; Bastidas-Salamanca et al ., 2017). These circulation patterns, geomorphological features and local processes such as the La Guajira upwelling, inland water discharges from the Magdalena River and the Panama-Colombia counter-current modulate the oceanic environment and have an effect on the structure of the water column, causing copepod assemblages to change from one location to another (Andrade & Barton, 2005; Medellín-Mora & Martínez-Ramírez, 2010; Gutiérrez-Salcedo, 2011; Medellín-Mora et al ., 2018).…”