A basin-wide Black Sea Mnemiopsis leidyi database

A specific marine biological data management tool, the Black Sea Mnemiopsis leidyi database system was created within the European Commission 6th framework Black Sea SCENE project for the Black Sea region and is now being supported by the Permanent Secretariat of the Black Sea Commission. The core team of scientists studying M. leidyi in the Black Sea was brought together and all their available M. leidyi data and metadata were loaded into the common database. This works on the Internet and has a simple user interface. It gives Black Sea scientists the option to load all their corresponding data on the database and to use it as an effective tool to work both with M. leidyi and, in future, with other gelatinous organisms’ data, including another invasive ctenophore Beroe ovata. All loaded metadata and historical data are available to the entire scientific community. More recent data are available to the team members and with some restrictions to other scientists.JRC.H.5-Land Resources Managemen

Ocean current connectivity propelling the secondary spread of a marine invasive comb jelly across western Eurasia

Publication history: Accepted - 15 February 2018; Published - 16 May 2018.Aim: Invasive species are of increasing global concern. Nevertheless, the mechanisms driving further distribution after the initial establishment of non-native species remain largely unresolved, especially in marine systems. Ocean currents can be a major driver governing range occupancy, but this has not been accounted for in most invasion ecology studies so far. We investigate how well initial establishment areas are interconnected to later occupancy regions to test for the potential role of ocean currents driving secondary spread dynamics in order to infer invasion corridors and the source–sink dynamics of a non-native holoplanktonic biological probe species on a continental scale. Location: Western Eurasia. Time period: 1980s–2016. Major taxa studied: ‘Comb jelly’ Mnemiopsis leidyi. Methods: Based on 12,400 geo-referenced occurrence data, we reconstruct the invasion history of M. leidyi in western Eurasia. We model ocean currents and calculate their stability to match the temporal and spatial spread dynamics with large-scale connectivity patterns via ocean currents. Additionally, genetic markers are used to test the predicted connectivity between subpopulations. Results: Ocean currents can explain secondary spread dynamics, matching observed range expansions and the timing of first occurrence of our holoplanktonic non-native biological probe species, leading to invasion corridors in western Eurasia. In northern Europe, regional extinctions after cold winters were followed by rapid recolonizations at a speed of up to 2,000 km per season. Source areas hosting year-round populations in highly interconnected regions can re-seed genotypes over large distances after local extinctions. Main conclusions: Although the release of ballast water from container ships may contribute to the dispersal of non-native species, our results highlight the importance of ocean currents driving secondary spread dynamics. Highly interconnected areas hosting invasive species are crucial for secondary spread dynamics on a continental scale. Invasion risk assessments should consider large-scale connectivity patterns and the potential source regions of non-native marine species.Danish Council for Independent Research; Grant/Award Number: DFF-1325-00102B; FP7 People: Marie-Curie Actions, Grant/Award Number: MOBILEX, DFF - 1325-00025; EU, BONUS, BMBF, Grant/ Award Number: 03F0682; Excellence Cluster “Future Ocean”, Grant/Award Number: CP153

Parameters of population dynamics and energetics of ctenophore Mnemiopsis leidyi in Sevastopol Bay from January 1995 to March 1996

Population dynamics of abundance and biomass were studied and specific production of population of ctenophore Mnemiopsis leidyi was estimated in the Sevastopol Bay from January 1995 to March 1996. The ctenophores achieved maximum abundance and biomass in July during period of intensive reproduction. Young specimens (<5 mm) contributed during that period as much as 50-87% to total abundance of population. Annually averaged daily specific growth rate was 0.039. Growth, food consumption, and rate of filtration were measured in a laboratory under two concentrations of food (Acartia clausi and Moina micrura: 60 and 100 specimens per liter, 0.35 and 0.60 mg wet weight/l). Both concentrations sustained growth of animals with dry weight less than 20 mg. However these concentrations were insufficient to sustain growth of larger ctenophores. Specific growth rate of the ctenophores with dry weight <20 mg under favorable food conditions was 0.20-0.30 l/day. Specific growth rate of the ctenophores in the Sevastopol Bay never exceeded 0.093 l/day, mean biomass of fodder zooplankton in the bay being 90 mg/m**3 in terms of wet weight. Hence a conclusion was made that population of M. leidyi in the bay was limited by lack of food

Trophic ecology and assessment of the predatory impact of the Moon jellyfish Aurelia aurita (Linnaeus, 1758) on zooplankton in the Black Sea

Experiments on the feeding of the Moon jellyfish Aurelia aurita have shown that digestion time of zooplankton typically varies between 2.2 and 5.1 h depending on the body weight of the predator, diet composition, amount of food, and seawater temperature. The daily ration of a Moon jellyfish with a wet body mass of 1 g reached 0.025-2.845 mg zooplankton.ind(-1).day(-1) corresponding to a carbon-specific food uptake of 0.2-9.1% C day(-1) with a mean value around 0.5% C day(-1). Such mesozooplankton consumption rates are consistent with the ration values (around 0.9% C day(-1)) calculated from the feeding rate experiments of jellyfish at natural food concentrations. However, in both cases the amount of mesozooplankton was insufficient to compensate for the minimum food requirements, calculated from oxygen consumption (6.7 +/- 0.6% C day(-1)) of the jellyfish. On average, the metabolic expenses of A. aurita were about one order of magnitude greater than its ration supplied by mesozooplankton, indicating the important role of visually overlooked food components in the jellyfish diet

Invasive Ctenophore Mnemiopsis Leidyi in the Caspian Sea: Feeding, Respiration, Reproduction and the Predatory Impact on Zooplankton Community

The impact of the invasive ctenophore Mnemiopsis leidyi on the zooplankton community of the Caspian Sea was quantified according to food consumption and other major physiological activities (i.e. respiration and reproduction), coupled with field data on population structure. The adverse effects of M.leidyi on the zooplankton community during the first years of the invasion were tremendous for the Caspian Sea compared to other regions affected by this ctenophore. The impact was highest in summer, due to high water temperatures and a population size structure in which juvenile ctenophores with mean lengths of 2 to 5 mm accounted for most of the population. During winter/spring, these ctenophores could consume the available stock of zooplankton in 3 to 8 d, whereas in summer consumption took only 1 d. The computed critical ctenophore biomass that does not affect (decrease) the abundance of mesozooplankton in the Caspian Sea is about 4 g m3 (or 120 g m2, assuming most of the ctenophores occur in the upper 30 m layer). As is clear from the monitoring data, the M.leidyi biomass in summer in different regions of the Caspian Sea is far in excess of this value. Such a high abundance of ctenophores, if maintained, would constantly keep the nongelatinous zooplankton biomass at very low levels, and, as a consequence, no recovery could be expected in the pelagic fishery.JRC.G.3-Agricultur

Spatial Distribution, Population Structure, and Predatory Impact of Gelatinous Predators on Zooplankton Community in Inshore Waters off Crimean Coast of the Black Sea

Приводятся данные по распределению и хищничеству желетелого макропланктона на шельфе Крыма в апреле 2016 г. В районах исследований желетелый макропланктон был представлен сцифомедузой Aurelia aurita (Linnaeus, 1758) и тремя видами гребневиков (Mnemiopsis leidyi A. Agassiz, 1865, Beroe ovata Bruguire, 1789, Pleurobrachia pileus (O. F. Müller, 1776)). A. aurita всюду доминировала по биомассе, изменявшейся в пределах от ~62 до 1330 г·м‑2 в разных районах. Максимальная биомасса медуз A. aurita отмечена в районе Южного берега Крыма, минимальная – в районе Каркинитского залива, что при высокой численности говорит о преобладании в популяции мелких животных. Размерная структура популяции A. aurita различалась по районам с увеличением доли крупных медуз с запада на восток. Гребневик M. leidyi при небольшой численности (0,33–1,45 экз·м‑2) и биомассе (<1–51,7 г·м‑2) (исключение – станция в Керченском проливе, где численность составляла 2 экз·м‑2, а биомасса – 126,3 г·м‑2) встречался в Черном море лишь на 33– 45 % станций (исключение – Каркинитский залив –17 %). В популяции преобладали крупные взрослые животные 55–70 мм. Биомасса P. pileus во всех районах была ниже биомассы A. aurita и M. leidyi при значительно более высокой его численности. Суточные рационы A. aurita варьировали в широких пределах как внутри каждого района, так и от района к району. Величина суточного рациона в отдельных районах и на всей исследованной акватории коррелировала с содержанием углерода в теле медуз. Выедание зоопланктона A. aurita на шельфе Крыма было очень низким и не приводило к кардинальному сокращению численности зоопланктона. Влияние M. leidyi, даже при его низкой численности и биомассе, было значительно выше по сравнению с медузамиThe study reports the data on the distribution and predatory impact of the gelatinous macroplankton on mesozooplankton in the inshore waters of Crimea in April 2016. In the study areas, gelatinous macroplankton comprised Scyphomedusae Aurelia aurita (Linnaeus, 1758) and three ctenophore species (Mnemiopsis leidyi A. Agassiz, 1865, Beroe ovata Bruguire, 1789, and Pleurobrachia pileus (O. F. Müller, 1776). The biomass of A. aurita dominated everywhere and varied from ~ 62 to 330 g·m‑2 in different areas. The largest A. aurita biomass was observed in the South Coast of Crimea and the smallest in Karkinitsky Bay, where the number of jellyfish was high, suggesting the predominance of small individuals in the population. The size structure of A. aurita population differed by region: the proportion of large animals increased from the West to the East. The abundance and biomass of M. leidyi were rather low: 0.33–1.45 ind·m‑2 and 1–51.7 g·m‑2, respectively (the exception was the position in the Kerch Strait, where M. leidyi abundance reached 2 ind. m‑2 and biomass 126.3 g·m‑2); that species occurred only at 33–45 % of the stations (the exception was Karkinitsky Bay – 17 %), with the maximum values in the South Coast of Crimea. Large, 55–70-mm, adult individuals predominated. P. pileus biomass was lower than the biomass of A. aurita and M. leidyi in all areas, but its abundance was much higher. The daily rations of A. aurita varied widely both in the entire area and from one region to another. The daily ration values correlated with the carbon content in A. aurita body. The predation pressure of A. aurita on zooplankton in the inshore waters of Crimea was very low and did not result in a crucial decrease in mesozooplankton abundance. The effect of M. leidyi, even with its low abundance and biomass, was much stronge

Invasive ctenophore Mnemiopsis leidyi in the Caspian Sea: feeding, respiration, reproduction and predatory impact on the zooplankton community

The impact of the invasive ctenophore Mnemiopsis leidyi on the zooplankton community of the Caspian Sea was quantified according to food consumption and other major physiological activities (i.e. respiration and reproduction), coupled with field data on population structure. The adverse effects of M. leidyi on the zooplankton community during the first years of the invasion were tremendous for the Caspian Sea compared to other regions affected by this ctenophore. The impact was highest in summer, due to high water temperatures and a population size structure in which juvenile ctenophores with mean lengths of 2 to 5 mm. accounted for most of the population. During winter/spring, these ctenophores could consume the available stock of zooplankton in 3 to 8 d, whereas in summer consumption took only 1 d. The computed critical ctenophore biomass that does not affect (decrease) the abundance of mesozooplankton in the Caspian Sea is about 4 g m(-3) (or 120 g m(-2), assuming most of the ctenophores occur in the upper 30 m layer). As is clear from the monitoring data, the M. leidyi biomass in summer in different regions of the Caspian Sea is far in excess of this value. Such a high abundance of ctenophores, if maintained, would constantly keep the non-gelatinous zooplankton biomass at very low levels, and, as a consequence, no recovery could be expected in the pelagic fishery