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Abstract Zooplankton was sampled in the Southern Gulf of Mexico, during autumn 2010, summer 2011 and winter 2013. Hydrographic data, dynamic topography and geostrophic velocities showed the presence of alternating cyclonic and anticyclonic gyres in the area, and a quasi-permanent gyre in the Bay of Campeche, with higher surface temperatures and lower salinities during autumn and summer, than in winter. Stronger rainfall was present during summer, which coincided with a strong salps "bloom" that considerably increased biovolumes. A significant difference in biovolumes was found for the three seasons, with highest zooplankton biovolumes during summer, and lowest during autumn. A shoaling of higher fluorescence and higher nutrients (Nitrate + Nitrite) was found in the BOC, in coincidence with higher biovolumes during the three seasons sampled. Multivariate analysis showed that the variables controlling the productivity were mainly fluorescence and nutrients for summer 2011 and winter 2013. Higher biovolumes were present in autumn, summer and winter at the same stations, being higher during summer. Data obtained show that the Bay of Campeche is a high productivity area, all year round, particularly inside the quasi-permanent gyre where high biovolumes were present in autumn, summer and winter, but with considerable seasonal variations in primary and secondary productivity, probably dependent in great measure from river discharge and rainfall. Highlights • Campeche Bay has high productivity during the entire year, around the quasi-permanent gyre. • A shoaling of high fluorescence and high nutrients produces higher biovolumes of zooplankton. • The seasonal variability is always higher in the studied area of Campeche Bay. [ABSTRACT FROM AUTHOR]

The copepod Calanus glacialis is endemic to the Arctic Ocean and peripheral seas and forms a key component of the Arctic marine ecosystems. It is the major contributor to zooplankton biomass, a predominant grazer, and an important prey for seabirds, and fish. As for a planktonic species, its dispersal is expected to be widespread and mediated by ocean currents. However, complex circulation patterns and the existence of semi-enclosed fjords and seas in the Arctic can be hypothesized to influence the population genetic structure of this species. In this study, we aimed to infer patterns of connectivity between populations of C. glacialis distributed around the Arctic and across putative barriers formed by oceanographic currents and semi-enclosed fjords and seas. To achieve this, we used 11 polymorphic microsatellite loci to genotype 189 individuals from 7 locations: Svalbard fjords (Kongsfjorden, Hornsund, Isfjorden, Rijpfjorden, and Storfjorden), White Sea, and Amundsen Gulf, thus providing greater genetic resolution over a larger biogeographical scale than in previous studies. The results revealed a lack of structure among all seven locations around the Arctic, indicating a panmictic population with large-scale gene flow. This study also supports the hypothesis that the planktonic fauna of the White Sea is not isolated from that of the other Arctic regions. [ABSTRACT FROM AUTHOR]

The article discusses a study that used an optical plankton counter (OPC) to assess temporal and spatial changes in the zooplankton size spectra in Japan's neighboring waters from May to August 2011. Topics covered include zooplankton groups observed in the northern Japan Sea, Okhotsk Sea and Kuroshio extension, temporal changes resulting from the seasonal vertical descent of Neocalanus copepods, and the slope of the normalized biomass size spectra (NBSS) of the stable marine ecosystem.

The article presents research which examined the presence of Antarctic copepods in Antarctic Chilean Peninsula in 2012. Topics covered include the impact of oceanographic conditions on their physical conditions as well as diversity. Also mentioned is the assessment of the distribution patterns of zooplankton in the area.

Diel vertical migration (DVM) is a common behavior adopted by zooplankton species. DVM is a prominent adaptation for avoiding visual predation during daylight hours and still being able to feed on surface phytoplankton blooms during night. Here, we report on a DVM study using a Video Plankton Recorder (VPR), a tool that allows mapping of vertical zooplankton distributions with a far greater spatial resolution than conventional zooplankton nets. The study took place over a full day-night cycle in Disko Bay, Greenland, during the peak of the phytoplankton spring bloom. The sampling revealed a large abundance of copepods performing DVM (up during night and down during day). Migration behavior was expressed differently among the abundant groups with either a strong DVM (euphausiids), an absence of DVM (i.e., permanently deep; ostracods) or a marked DVM, driven by strong surface avoidance during the day and more variable depth preferences at night ( Calanus spp.). The precise individual depth position provided by the VPR allowed us to conclude that the escape from surface waters during daytime reduces feeding opportunities but also lowers the risk of predation (by reducing the light exposure) and thereby is likely to influence both state (hunger, weight and stage) and survival. The results suggest that the copepods select day and night time habitats with similar light levels (~10 μmol photon s m). Furthermore, Calanus spp. displayed state-dependent behavior, with DVM most apparent for smaller individuals, and a deeper residence depth for the larger individuals. [ABSTRACT FROM AUTHOR]

The paper presents data on the structure of total zooplankton according to comparison of microfraction and mesofraction of quantitatively important zooplankton groups in the Jabuka Pit region. Research work was carried out during six cruises from 1986 to 1992 in the framework of the Adriatic Scientific Coordinating Programme (ASCOP). The samples were collected by vertical tows in three layers (50 to 0 meters, 100 to 50 meters and bottom to 100 meters). The microzooplankton was sampled with a 53 μm Nansen net equipped with a closing device and mesozooplankton with a Juday-Bogorov 250 μm net. There was no significant difference in zooplankton abundances between the eastern and western part of Jabuka Pit. The differences in the vertical distribution pattern, precisely between the surface and near the bottom samples were significant. Qualitative composition of some of the zooplankton groups differ between the western and eastern part of the Pit primarily due to the appearance of oceanic species in its eastern part, carried with mediterranean and south Adriatic water masses. This influence was most pronounced in December 1986 and August 1992. It should be noted that in September 1987 and in August 1992, small Oithona and Oncaea genera' copepods prevailed, whereas in December 1986, May 1987 and August 1990, the calanoids were the dominant group. [ABSTRACT FROM AUTHOR]

During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historical context to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference for changes in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms. [ABSTRACT FROM AUTHOR]

New baseline information is presented on biogeography, abundance and distribution of euphausiids from discrete depth samples collected throughout the water column to 3000 m at 42 locations along the Mid-Atlantic Ridge (MAR) between Iceland and the Azores. Eighteen species were recorded, with Euphausia krohni and Thysanoessa longicaudata being most abundant. Eight species had not been recorded in the area previously. The Subpolar Front is a northern boundary to some southern species, but not a southern boundary to northern ubiquitous species that show submergence. Four major species assemblages were identified and characterized in terms of spatial distribution and species composition. Numerical abundance was highly variable but decreased logarithmically with depth. The greatest average abundance and the greatest spatial variation in abundance occurred in northern waters, over the Reykjanes Ridge. Abundance declined less with depth in the sub-Arctic Intermediate Water/North Atlantic Current Water than in other areas and water masses. The near bottom layer (0–200 m from the seabed) had typically low density of euphausiids. The MAR is generally deeper than the usual depth distribution of euphausiids (0–300 m), but many species conduct vertical migrations to ridge crest depths. Euphausiid distribution and abundance patterns appeared only weakly affected by the MAR. [ABSTRACT FROM AUTHOR]

The genus Pseudocalanus (Copepoda, Calanoida) consists of seven species, all of which are known to co-occur with two or more sibling species in some areas of their geographic ranges. Despite the ecological importance of this abundant genus, there is no available method that can reliably and accurately identify Pseudocalanus species without knowledge of origin. We present evidence of several observations of Pseudocalanus moultoni [Frost (1989) Can. J. Zool., 67, 525–551] in fjords of Svalbard and northern Norway; this species has previously been known to occur only on the east and west coasts of North America. Patterns of DNA sequence variation of the mitochondrial cytochrome oxidase subunit I (COI) gene allow us to confidently identify the species, discriminate it from co-occurring sibling species and infer relationships among the newly discovered and previously sampled P. moultoni populations. Our observations suggest that NE Atlantic populations of P. moultoni are self-sustaining and we discuss potential source populations and pathways of transport. In light of recent reports of climate-driven shifts in distributional ranges of marine zooplankton, accurate species identification is essential for monitoring and understanding marine ecosystems. [ABSTRACT FROM AUTHOR]

The article discusses research on the physical control of the distribution of zooplankton at the Strait of Gibraltar in an episode of internal wave generation. It references a study by D. Macís at the Universidad de Cádiz in Spain, and his colleagues, published in the June 3, 2010 issue of "Marine Ecology Progress Series." The researchers studied the effect of physical forcing on the distribution of zooplankton biomass as a tidal phase function. They conclude the significance of physical forcing on biogeochemical distributions in the main channel of the Strait of Gibraltar, which has already been pointed out in various studies.

Large-scale biogeographical changes in the biodiversity of a key zooplankton group (calanoid copepods) were detected in the north-eastern part of the North Atlantic Ocean and its adjacent seas over the period 1960–1999. These findings provided key empirical evidence for climate change impacts on marine ecosystems at the regional to oceanic scale. Since 1999, global temperatures have continued to rise in the region. Here, we extend the analysis to the period 1958–2005 using all calanoid copepod species assemblages (nine species assemblages based on an analysis including a total of 108 calanoid species or taxa) and show that this phenomenon has been reinforced in all regions. Our study reveals that the biodiversity of calanoid copepods are responding quickly to sea surface temperature (SST) rise by moving geographically northward at a rapid rate up to about 23.16 km yr−1. Our analysis suggests that nearly half of the increase in sea temperature in the northeast Atlantic and adjacent seas is related to global temperature rises (46.35% of the total variance of temperature) while changes in both natural modes of atmospheric and oceanic circulation explain 26.45% of the total variance of temperature. Although some SST isotherms have moved northwards by an average rate of up to 21.75 km yr−1 (e.g. the North Sea), their movement cannot fully quantify all species assemblage shifts. Furthermore, the observed rates of biogeographical movements are far greater than those observed in the terrestrial realm. Here, we discuss the processes that may explain such a discrepancy and suggest that the differences are mainly explained by the fluid nature of the pelagic domain, the life cycle of the zooplankton and the lesser anthropogenic influence (e.g. exploitation, habitat fragmentation) on these organisms. We also hypothesize that despite changes in the path and intensity of the oceanic currents that may modify quickly and greatly pelagic zooplankton species, these organisms may reflect better the current impact of climate warming on ecosystems as terrestrial organisms are likely to significantly lag the current impact of climate change. [ABSTRACT FROM AUTHOR]

The article presents a study which focuses on the geographical distribution of zooplankton carbon demand and its day or night variability. It emphasizes that the zooplankton community plays an important role in the binding activity of biological carbon in the epipelagic marine ecosystem. The evaluation of zooplankton carbon requirements is determined through the respiration rates of the Electron Transport System (ETS) activity in the mitochondrial membrane. The samples were measured over a 24-hour period in the top 200 meters of the water column at ten sampling stations across the Mediterranean Sea, such as the Strait of Gibraltar and the Isle of Rhodes. The researchers investigate the zooplankton's species composition, biomass, and abundance to interpret ETS.

Abstract: As part of the international MENU collaboration, we compared and contrasted ecosystem responses to climate-forced oceanographic variability across several high latitude regions of the North Pacific (Eastern Bering Sea (EBS) and Gulf of Alaska (GOA)) and North Atlantic Oceans (Gulf of Maine/Georges Bank (GOM/GB) and the Norwegian/Barents Seas (NOR/BAR)). Differences in the nitrate content of deep source waters and incoming solar radiation largely explain differences in average primary productivity among these ecosystems. We compared trends in productivity and abundance at various trophic levels and their relationships with sea-surface temperature. Annual net primary production generally increases with annual mean sea-surface temperature between systems and within the EBS, BAR, and GOM/GB. Zooplankton biomass appears to be controlled by both top-down (predation by fish) and bottom-up forcing (advection, SST) in the BAR and NOR regions. In contrast, zooplankton in the GOM/GB region showed no evidence of top-down forcing but appeared to control production of major fish populations through bottom-up processes that are independent of temperature variability. Recruitment of several fish stocks is significantly and positively correlated with temperature in the EBS and BAR, but cod and pollock recruitment in the EBS has been negatively correlated with temperature since the 1977 shift to generally warmer conditions. In each of the ecosystems, fish species showed a general poleward movement in response to warming. In addition, the distribution of groundfish in the EBS has shown a more complex, non-linear response to warming resulting from internal community dynamics. Responses to recent warming differ across systems and appear to be more direct and more pronounced in the higher latitude systems where food webs and trophic interactions are simpler and where both zooplankton and fish species are often limited by cold temperatures. [Copyright &y& Elsevier]

The Mediterranean Sea is located in a crossroad of mid-latitude and subtropical climatic modes that enhance contrasting environmental conditions over both latitudinal and longitudinal ranges. Here, we show that the large-scale environmental forcing is reflected in the basin scale trends of the adult population of the calanoid copepod Centropages typicus. The species is distributed over the whole Mediterranean basin, and maximal abundances were found in the north-western basin associated to oceanic fronts, and in the Adriatic Sea associated to shallow and semi enclosed waters. The peak of main abundances of C. typicus correlates with the latitudinal temperature gradient and the highest seasonal abundances occurred in spring within the 14–18°C temperature window. Such thermal cline may define the latitudinal geographic region where C. typicus seasonally dominates the >200 μm-sized spring copepod community in the Mediterranean Sea. The approach used here is generally applicable to investigate the large-scale spatial patterns of other planktonic organisms and to identify favourable environmental windows for population development. [ABSTRACT FROM AUTHOR]

Factors affecting mesozooplankton distributions in the northeastern tropical Pacific Ocean were investigated using data obtained along a meridian line (5°–12°N, 131.5°W) in the summers of 1998, 1999, and 2003. The survey periods corresponded to a sharp transition between the 1997–1998 El Niño and 1998–1999 La Niña events, the 1999 La Niña event, and near-normal conditions after the moderate 2002–2003 El Niño in the equatorial Pacific. A strong upwelling in the divergence zone from 10.5° to 11°N caused a shoaling of the thermocline depth (∼30m), resulting in increases in nitrate and phytoplankton chlorophyll a (chl-a) concentrations, and, in turn, mesozooplankton abundance during the La Niña in 1999. In contrast, in 1998, remnants of El Niño characteristics, deeper thermocline depth (60–150m) and warm surface water (>28°C), led to low concentrations of nitrate, chl-a and low mesozooplankton abundance, except in the convergence zone around 7°N. The thermocline depth and nitrate concentration obtained during the near-normal period in 2003 corresponded to intermediate values as compared to those obtained during El Niño and La Niña conditions. Interannual changes in the position and strength of ecotones, such as divergence and convergence zones, affected mesozooplankton community structure and cyclopoid-to-calanoid ratios along the 131.5°W meridian line. The clustering pattern of the mesozooplankton community was mostly characterized by calanoid (mainly Clausocalanus sp.) and cyclopoid (mainly Oncaea sp.) copepods, accounting for most of the observed differences among groups during the study period. Cyclopoids and calanoids were more abundant in 1999 than in 1998 or 2003, with a sharp increase to the north, while they were less abundant to the north in 1998 and 2003. The cyclopoid-to-calanoid ratio peaked in the convergence zone in 1998 and the divergence zones in 1999 and 2003, apparently due to the strength and location of the ecotones. Principal component analysis (PCA) with environmental factors and dominant mesozooplankton groups showed that dominant groups were affected by nitrate and chl-a concentrations in 1998, by sigma-t (water density), nitrate and chl-a concentrations in 1999, and by sigma-t, salinity and chl-a concentration (except siphonophores) in 2003. Latitudinal distribution of thermocline depth before and after the 1998/99 La Niña event showed a distinct interannual difference. The abundance of mesozooplankton in the divergence zone in 1999 was distinctively higher than abundances found in the convergence and divergence zones in 1998 and 2003, which resulted from the shallow thermocline depth due to an intensified upwelling during the strong 1998–1999 La Niña event. [Copyright &y& Elsevier]

Temporal and spatial variability of micro and mesozooplankton was studied in 1998 and 1999 at four stations in the Neretva Channel area influenced by the Neretva river and the open waters of the south Adriatic Sea. The area is orthophosphate limited, but an excessive accumulation of land derived nitrogen is prevented by phytoplankton uptake and the general circulation pattern. Microzooplankton was dominated by ciliates, with average abundances comparable to other Adriatic channel areas (122-543 ind. l). Non-loricate ciliates (NLC) generally peaked in the warmer periods, but a winter increase was evident towards the inner part of the channel. Tintinnid abundances generally increased in autumn. A significant relationship with temperature was not recorded for either protozoan group. An inverse relationship between NLC and salinity might be indirectly caused by their preference for the food abundant surface layer. Mesozooplankton was dominated by copepods, with distinct summer maxima throughout the area and pronounced winter maxima of >10,000 ind. m at the inner stations. The community was predominantly neritic but the open sea waters were important in structuring the mesozooplankton assemblage at all stations during the autumn-winter period. Although temperature regulated the seasonal dynamics of most metazoans and the species succession in the copepod community, small omnivorous copepods ( Oncaea media complex, Oithona nana and Euterpina acutifrons) dominated regardless of the season. A trophic link between copepods and ciliates was evident in winter during low phytoplankton biomass. [ABSTRACT FROM AUTHOR]

The distribution of phytoplankton and zooplankton around three sandbanks (Gootebank, Westhinder and Buitenratel sandbank) off the Belgian Coast was investigated in February 1994. The abundance of phytoplankton taxa was significantly different between the sandbanks. Community analysis using TWINSPAN resulted in a clear separation of clusters corresponding to the different sandbanks. The zooplankton community analysis, on the contrary, showed a rather indistinctive division of the sandbank stations. This was due to the omnipresence of three dominant copepod species (Temora longicornis, Pseudocalanus elongatus and Centropages hamatus). When these species were excluded from the analysis, a clearer distinction between the different sandbanks was found. The observed differences in phyto- and zooplankton species distribution could be explained by the position of the sandbanks. Westhinder is positioned further from the coast than Buitenratel, while Gootebank has an intermediate position. Buitenratel and Gootebank harbour typical coastal plankton communities, while the plankton community over Westhinder is clearly influenced by the Atlantic current penetrating the southern North Sea from the English channel. More phyto-benthic species were found at Buitenratel than at Gootebank, probably because of its limited depth. Thus, the Belgian coastal zone, which is considered as one box in most spatial descriptions of the North Sea plankton, in fact harbours heterogeneous plankton communities at the end of winter. [ABSTRACT FROM PUBLISHER]

The distribution of total dry weight of zooplankton, copepod numbers and ichthyoplankton across the outer continental shelf in the central Great Barrier Reef was examined at bi-weekly intervals for three months over summer of 1983. Copepods were sampled (236 μm net) within 10 m of the surface and within 10 m of the bottom. Mean densities in surface waters decreased markedly from the mid-shelf to outer shelf and the Coral Sea, but no cross-shelf gradient occurred in the bottom-water. Densities of copepods on the mid-shelf (surface and bottom waters) and in bottom-waters of the outer shelf were typically ca. 400 m. Significantly lower densities (ca. 100 m) occurred in surface waters of the outer shelf, except during outbursts of Acartia australis, when densities in these waters differed little from those elsewhere on the shelf. In oceanic waters, 10 km from the outer shelf station, copepod densities in surface waters were ca. 40 m. Four of the five most abundant copepod taxa in surface waters, Paracalanus spp., Eucalanus crassus, Acrocalanus gracilis and Canthocalanus pauper, tended to be most abundant at the mid-shelf end of the transect. Acartia australis was sporadically very abundant in surface waters of the outer shelf, as was Paracalanus spp. in bottom-water of the outer shelf. An assemblage of Coral Sea species of copepod occurred in bottom-water of the outer shelf during two major intrusions, but not at other times. Densities of all common species varied considerably between cruises. Maximum densities of all common species except A. australis tended to be associated with diatom blooms linked to intrusions but a bloom did not necessarily mean all common species were abundant. Fish larvae included both reef and non-reef taxa, with reef taxa predominating on the outer shelf (approx 2:1 in density of individuals) and non-reef taxa dominating in nearshore samples (approx 2:1). Nine of the ten most abundant taxa analysed showed highly significant variation in numbers among stations and all but one of these also exhibited significant station x cruise interactions. Interactions generally reflected changes in the rank importance of adjacent stations from one cruise to the next or lack of any significant cross-shelf variation on some cruises where overall abundance of the taxa was low. [ABSTRACT FROM AUTHOR]

The present study details the effects of basin-scale hydrographic characteristics of the Red Sea on the macroecology of Chaetognatha, a major plankton component in the pelagic realm. The hydrographic attributes and circulation of the Red Sea as a result of its limited connection with the northern Indian Ocean make it a unique ecohydrographic region in the world ocean. Here, we aimed to identify the prime determinants governing the community structure and vertical distribution of the Cheatognatha in this ecologically significant world ocean basin. The intrusion of Gulf of Aden Water influenced the Chaetognatha community composition in the south, whereas the overturning circulation altered their vertical distribution in the north. The existence of hypoxic waters (< 100 µmol kg−1) at mid-depth also influenced their vertical distribution. The detailed evaluation of the responses of the different life stages of Chaetognatha revealed an increased susceptibility of adult individuals to hypoxic waters compared to immature stages. Higher oxygen demands of the adults for the egg and sperm production might have prevented them from inhabiting the oxygen-deficient mid-depth zones. The carbon and nitrogen content of the Copepoda and Chaetognatha communities and the quantification of the predation impact of Chaetognatha on Copepoda based on the feeding rate helped in corroborating the significant trophic link between these two prey-predator taxa. The observed influences of physical and chemical attributes on the distribution of Chaetognatha can be used as a model example for the role of the hydrography on the zooplankton community of the Red Sea. [ABSTRACT FROM AUTHOR]