Effects of environmental variability on different trophic levels of the North Atlantic food web

2013 ◽  
Vol 477 ◽  
pp. 15-28 ◽  
Author(s):  
VH Paiva ◽  
P Geraldes ◽  
V Marques ◽  
R Rodríguez ◽  
S Garthe ◽  
...  
Keyword(s):  
Food Web ◽  
North Atlantic ◽  
Environmental Variability ◽  
Trophic Levels ◽  
The North ◽  
The North Atlantic

scholarly journals Synchronous ecological regime shifts in the central Baltic and the North Sea in the late 1980s

2005 ◽  
Vol 62 (7) ◽  
pp. 1205-1215 ◽  
Author(s):  
J. Alheit ◽  
C. Möllmann ◽  
J. Dutz ◽  
G. Kornilovs ◽  
P. Loewe ◽  
...  
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Climatic Variability ◽  
Regime Shifts ◽  
Trophic Levels ◽  
Copepod Species ◽  
The North ◽  
The North Sea ◽  
The North Atlantic ◽  
Low Levels

Abstract The index of the North Atlantic Oscillation, the dominant mode of climatic variability in the North Atlantic region, changed in the late 1980s (1987–1989) from a negative to a positive phase. This led to regime shifts in the ecology of the North Sea (NS) and the central Baltic Sea (CBS), which involved all trophic levels in the pelagial of these two neighbouring continental shelf seas. Increasing air and sea surface temperatures, which affected critical physical and biological processes, were the main direct and indirect driving forces. After 1987, phytoplankton biomass in both systems increased and the growing season was extended. The composition of phyto- and zooplankton communities in both seas changed conspicuously, e.g. dinoflagellate abundance increased and diatom abundance decreased in the CBS. Key copepod species that are essential in fish diets experienced pronounced changes in biomass. Abundance of Calanus finmarchicus (NS) and Pseudocalanus sp. (CBS) fell to low levels, whereas C. helgolandicus (NS) and Temora longicornis and Acartia spp. (CBS) were persistently abundant. These changes in biomass of different copepod species had dramatic consequences on biomass, fisheries, and landings of key fish species: North Sea cod declined, cod in the CBS remained at low levels, and CBS sprat reached unprecedented high biomass levels resulting in high yields. The synchronous regime shifts in NS and CBS resulted in profound changes in both marine ecosystems. However, the reaction of fish populations to the bottom-up mechanisms caused by the same climatic shift was very different for the three fish stocks.

Indicators for marine ecosystems affected by fisheries

2000 ◽  
Vol 51 (5) ◽  
pp. 447 ◽  
Author(s):  
Villy Christensen
Keyword(s):  
North Atlantic ◽  
Trophic Levels ◽  
Gulf Of Thailand ◽  
The North ◽  
The Gulf Of Thailand ◽  
The North Atlantic ◽  
Changes Over Time ◽  
The Impact ◽  
Ecological Dimension ◽  
Over Time

The paper explores two types of indicators: Odum’s 24 attributes for describing the state of an ecosystem based on its maturity; and the fishing-in-balance (FIB) index for describing how ecosystem exploitation changes over time. Application of the FIB index to the Gulf of Thailand and the North Atlantic fisheries, describing the development in fisheries catches and their trophic levels over time, reveals that the index is straightforward to parameterize and adds an ecological dimension to fisheries catch series; it is a useful indicator for assessing the impact of fisheries on ecosystems.

scholarly journals Basin-wide mechanisms for spring bloom initiation: how typical is the North Atlantic?

2015 ◽  
Vol 72 (6) ◽  
pp. 2029-2040 ◽  
Author(s):  
Harriet S. Cole ◽  
Stephanie Henson ◽  
Adrian P. Martin ◽  
Andrew Yool
Keyword(s):  
Interannual Variability ◽  
Mixed Layer ◽  
North Atlantic ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Theoretical Understanding ◽  
The North ◽  
The North Atlantic

Abstract The annual phytoplankton bloom is a key event in pelagic ecosystems. Variability in the timing, or phenology, of these blooms affects ecosystem dynamics with implications for carbon export efficiency and food availability for higher trophic levels. Furthermore, interannual variability in phytoplankton bloom timing may be used to monitor changes in the pelagic ecosystem that are either naturally or anthropogenically forced. The onset of the spring bloom has traditionally been thought to be controlled by the restratification of the water column and shoaling of the mixed layer, as encapsulated in Sverdrup's critical depth hypothesis. However, this has been challenged by recent studies which have put forward different mechanisms. For example, the critical turbulence hypothesis attributes bloom initiation to a reduction in turbulent mixing associated with the onset of positive net heat fluxes (NHFs). To date, the majority of studies on bloom initiation mechanisms have concentrated on North Atlantic datasets leaving their validity in other subpolar regions unknown. Here, we use chlorophyll output from a model that assimilates satellite ocean colour data to calculate bloom initiation timing and examine the basin-wide drivers of spatial and interannual variability. We find that the date that the NHF turns positive is a stronger predictor for the date of bloom initiation, both spatially and interannually, across the North Atlantic than changes in the mixed layer depth. However, results obtained from the North Pacific and Southern Ocean show no such basin-wide coherency. The lack of consistency in the response of the subpolar basins indicates that other drivers are likely responsible for variability in bloom initiation. This disparity between basins suggests that the North Atlantic bloom initiation processes are unique and therefore that this region may not be a suitable model for a global, theoretical understanding of the mechanisms leading to the onset of the spring bloom.

scholarly journals Environmental variability in the North Atlantic and Iberian waters and its influence on horse mackerel (Trachurus trachurus) and albacore (Thunnus alalunga) dynamics

2007 ◽  
Vol 64 (3) ◽  
pp. 425-438 ◽  
Author(s):  
Alicia Lavín ◽  
Xabier Moreno-Ventas ◽  
Victoria Ortiz de Zárate ◽  
Pablo Abaunza ◽  
José Manuel Cabanas
Keyword(s):  
North Atlantic ◽  
Environmental Conditions ◽  
Environmental Variability ◽  
Horse Mackerel ◽  
Wind Component ◽  
Trachurus Trachurus ◽  
The Third ◽  
The North ◽  
Thunnus Alalunga ◽  
The North Atlantic

Abstract Lavín, A., Moreno-Ventas, X., Ortiz de Zárate, V., Abaunza, P., and Cabanas, J. M. 2007. Environmental variability in the North Atlantic and Iberian waters and its influence on horse mackerel (Trachurus trachurus) and albacore (Thunnus alalunga) dynamics. – ICES Journal of Marine Science, 64: 425–438. We explore the potential impact of climatic and oceanic variables on the dynamics of horse mackerel Trachurus trachurus (coastal distribution) and albacore Thunnus alalunga (oceanic distribution). Principal components analysis of a set of environmental parameters for the years 1966–2000 allowed us to characterize the system by three components. The first consisted mainly of sea surface temperature (SST; 18.5% of variability), the second was determined by the oceanic transport indices, potential energy anomaly (PEA), and the Gulf Stream Index (15.6%), and the third by the meridional wind component and Ekman transport (11.5%). Horse mackerel recruitment was negatively correlated mainly with the first thermal component, whereas albacore age 3 catches were negatively correlated with the second oceanic component and positively with the third wind component. Multiple linear regression confirmed that environmental conditions [SST, PEA, and the zonal (east–west) wind component] explained the availability of age 3 albacore to the surface fisheries for the period 1975–1999. In contrast, cross-validation analysis showed that environmental conditions did not consistently explain horse mackerel recruitment, probably because of the short time-series available (15 y).

scholarly journals Coupled dynamics of dimethylsulfoniopropionate and dimethylsulfide cycling and the microbial food web in surface waters of the North Atlantic

2002 ◽  
Vol 47 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Rafel Simó ◽  
Stephen D. Archer ◽  
Carlos Pedrós-Alió ◽  
Linda Gilpin ◽  
Claire E. Stelfox-Widdicombe
Keyword(s):  
Food Web ◽  
North Atlantic ◽  
Surface Waters ◽  
Microbial Food Web ◽  
Coupled Dynamics ◽  
The North ◽  
The North Atlantic

scholarly journals Arctic boreal plankton species in the Northwest Atlantic

2001 ◽  
Vol 58 (11) ◽  
pp. 2121-2124 ◽  
Author(s):  
D G Johns ◽  
M Edwards ◽  
S D Batten
Keyword(s):  
North Atlantic ◽  
Sea Water ◽  
Trophic Levels ◽  
Northwest Atlantic ◽  
The North ◽  
Biological Responses ◽  
Calanus Hyperboreus ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Plankton Species

The Continuous Plankton Recorder (CPR) survey has sampled regularly in the Northwest Atlantic since the early 1960s. Over the last decade there has been a dramatic increase in the abundance of a number of arctic boreal plankton species, notably Calanus hyperboreus (Krøyer), Calanus glacialis (Jaschnov), and Ceratium arcticum, and a southerly shift of the copepod C. hyperboreus in the CPR survey. In 1998, C. hyperboreus was recorded at its farthest position south in the survey, 39°N, off the Georges Bank shelf edge. Other studies have reported similar parallel biological responses on three trophic levels. During the late 1990s, production of Labrador Sea Water (LSW) has been at a high, a direct response to the phase of the North Atlantic Oscillation (NAO). The increase in abundance of these species, up to four standard deviations from the long-term mean, is linked to variability in the hydrography of the area and the driving climatic processes of the North Atlantic.

scholarly journals Cod recruitment is strongly affected by climate when stock biomass is low

2005 ◽  
Vol 62 (3) ◽  
pp. 339-343 ◽  
Author(s):  
Keith M. Brander
Keyword(s):  
North Atlantic ◽  
Gadus Morhua ◽  
Environmental Variability ◽  
Atlantic Cod ◽  
Management Strategies ◽  
Pooled Analysis ◽  
The North ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The North Atlantic

Abstract Stocks of Atlantic cod (Gadus morhua) have been declining over much of the North Atlantic for the past 30 years, owing to a combination of overfishing and adverse changes in their environment. In a previous study, environmental effects were introduced as an extra parameter in the stock-recruit relationship, where they act as a multiplier, independent of the level of spawning-stock biomass (SSB). Using a non-parametric pooled analysis of all cod stocks on the European Shelf south of 62°N, it is shown here that environmental variability (as represented by the North Atlantic Oscillation) only has a significant effect on recruitment when the spawning stock is low. This has implications for fisheries management strategies, and for rates of stock recovery, which will be very dependent on environmental conditions.

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

2019 ◽  
pp. 73-81
Author(s):  
Oleh Poshedin
Keyword(s):  
North Atlantic ◽  
Task Force ◽  
Response Force ◽  
Cyber Attack ◽  
Adaptation Measures ◽  
Joint Force ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

Sign in / Sign up

Export Citation Format

Share Document