scholarly journals A millennium of trophic stability in Atlantic cod (Gadus morhua): transition to a lower and converging trophic niche in modern times

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guðbjörg Ásta Ólafsdóttir ◽  
Ragnar Edvardsson ◽  
Sandra Timsic ◽  
Ramona Harrison ◽  
William P. Patterson
Keyword(s):  
Trophic Ecology ◽  
Atlantic Cod ◽  
Marine Ecosystem ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Trophic Levels ◽  
Bone Collagen ◽  
Predatory Fish ◽  
Ecosystem Change ◽  
Data Set

AbstractStable isotope analyses of zooarchaeological material can be used to examine ecological variability in exploited species at centennial to millennial scales. Climate change is a notable driver of marine ecosystem change, although historical fishing is also likely to have impacted past marine systems. Fishing removes the oldest and largest individuals and may thereby result in shorter trophic pathways and reduced niche width of predatory fish species. In the current study we examine the trophic niche of Atlantic cod, haddock and Atlantic wolffish, in the last millennium using δ13C and δ15N values of bone collagen. We report a lower trophic level of Atlantic cod and haddock but higher level of wolffish in present times, following centuries at consistent and higher trophic levels of Atlantic cod. This results in a concurrent converging trophic niche of the demersal fish. We suggest that the current data set provides a valuable historical baseline facilitating interpretation of current variability in the trophic ecology of northern demersal fish.

scholarly journals Risk Assessment for Key Socio-Economic and Ecological Species in a Sub-Arctic Marine Ecosystem Under Combined Ocean Acidification and Warming

Ecosystems ◽  
2021 ◽  
Author(s):  
Maartje Oostdijk ◽  
Erla Sturludóttir ◽  
Maria J. Santos
Keyword(s):  
Ocean Acidification ◽  
Atlantic Cod ◽  
Marine Ecosystem ◽  
Keystone Species ◽  
Ecosystem Model ◽  
The Arctic ◽  
Predatory Fish ◽  
Important Species ◽  
Cascading Effects ◽  
Icelandic Waters

AbstractThe Arctic may be particularly vulnerable to the consequences of both ocean acidification (OA) and global warming, given the faster pace of these processes in comparison with global average speeds. Here, we use the Atlantis ecosystem model to assess how the trophic network of marine fishes and invertebrates in the Icelandic waters is responding to the combined pressures of OA and warming. We develop an approach where we first identify species by their economic (catch value), social (number of participants in fisheries), or ecological (keystone species) importance. We then use literature-determined ranges of sensitivity to OA and warming for different species and functional groups in the Icelandic waters to parametrize model runs for different scenarios of warming and OA. We found divergent species responses to warming and acidification levels; (mainly) planktonic groups and forage fish benefited while (mainly) benthic groups and predatory fish decreased under warming and acidification scenarios. Assuming conservative harvest rates for the largest catch-value species, Atlantic cod, we see that the population is projected to remain stable under even the harshest acidification and warming scenario. Further, for the scenarios where the model projects reductions in biomass of Atlantic cod, other species in the ecosystem increase, likely due to a reduction in competition and predation. These results highlight the interdependencies of multiple global change drivers and their cascading effects on trophic organization, and the continued high abundance of an important species from a socio-economic perspective in the Icelandic fisheries.

Trophic ecology of the chihuil sea catfish (Bagre panamensis) in the south-east Gulf of California, México

2017 ◽  
Vol 98 (4) ◽  
pp. 885-893 ◽  
Author(s):  
Víctor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Raul E. Lara-Mendoza ◽  
John T. Buszkiewicz ◽  
Felipe Amezcua-Linares
Keyword(s):  
Gulf Of California ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Levels ◽  
High Plasticity ◽  
Combined Use ◽  
Ecosystem Based Fisheries Management

The trophic ecology of the chihuil sea catfish Bagre panamensis was studied through high-resolution variations in its feeding habits and trophic position (TP) in the SE Gulf of California, relevant to sex, size and season. The combined use of stomach content (SCA) and stable isotope analysis (SIA) allowed us to perform these analyses and also estimate the TP of its preys. Results of this study show that the chihuil sea catfish is a generalist and opportunistic omnivore predator that consumes primarily demersal fish and peneid shrimps. Its diet did not vary with climatic season (rainy or dry), size or sex. Results from the SIA indicated high plasticity in habitat use and prey species. The estimated TP value was 4.19, which indicates a tertiary consumer from the soft bottom demersal community in the SE Gulf of California, preying on lower trophic levels, which aids in understanding the species' trophic role in the food web. Because this species and its prey are important to artisanal and industrial fisheries in the Gulf of California, diet assimilation information is useful for the potential establishment of an ecosystem-based fisheries management in the area.

Trophic ecology of the blue shark (Prionace glauca) based on stable isotopes (δ13C and δ15N) and stomach content

2015 ◽  
Vol 96 (7) ◽  
pp. 1403-1410 ◽  
Author(s):  
Sandra Berenice Hernández-Aguilar ◽  
Ofelia Escobar-Sánchez ◽  
Felipe Galván-Magaña ◽  
Leonardo Andrés Abitia-Cárdenas
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Trophic Ecology ◽  
Baja California ◽  
Marine Ecosystem ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Baja California Sur ◽  
Δ13c And Δ15n ◽  
Prionace Glauca

Occupying the upper levels of trophic webs and thus regulating prey at lower levels, sharks play an important role in the trophic structure and energy dynamics of marine ecosystems. In recent years, the removal of these individuals from upper trophic levels as a result of overfishing has negatively affected ecosystems. We analysed the diet of blue sharks (Prionace glauca) caught off the west coast of Baja California Sur, Mexico, during the months of February–June in 2001, 2005 and 2006. We employed both stomach content and stable isotope analyses as each method provides distinct yet important information regarding the role of blue sharks in marine food webs, allowing us to estimate the relative contribution of different prey items to this predator's diet. Of the 368 stomachs analysed, 210 contained food (57%) and 158 (43%) were empty. Based on stomach contents and the index of relative importance (IRI), the pelagic red crab (Pleuroncodes planipes) was the most important prey, followed by the squids Gonatus californiensis (34.1%) and Ancistrocheirus lesueurii (10.4%). The mean (±SD) values for δ15N (16.48 ± 0.94‰) and δ13C (−18.48 ± 0.63‰) suggest that blue sharks prefer feeding in oceanic waters. The trophic level based on stomach content analysis was 4.05, while that based on the stable isotope analysis was 3.8, making blue sharks top consumers in the marine ecosystem of Baja California Sur, Mexico.

scholarly journals How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry

2018 ◽  
Vol 75 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Diana M Matos ◽  
Jaime A Ramos ◽  
Joana G Calado ◽  
Filipe R Ceia ◽  
Jessica Hey ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Habitat Preferences ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Temporal Segregation ◽  
Fishery Discards ◽  
Individual Tracking ◽  
South Portugal

Abstract Fisheries produce large quantities of discards, an important resource for scavenging seabirds. However, a policy reform banning discards, which is soon to be implemented within the EU, will impose a food shortage upon scavengers, and it is still largely unknown how scavengers will behave. We studied the diet (hard remains), trophic (stable isotope analysis), and foraging (individual tracking) ecology of two gull species breeding in sympatry: Audouin’s gull Larus audouinii (AG) and yellow-legged gull Larus michahellis (YLG), in South Portugal, under normal fishery activity (NFA; work days) and low fishery activity (LFA; weekends), over two consecutive years. We established a pattern of dietary, spatial, and temporal segregation between the two gull species. Under LFA, yellow-legged gulls reduced their time spent at-sea, thus foraging more in alternative habitats (e.g. refuse dumps) and widening their isotopic niche (i.e. generalist behaviour). Contrastingly, Audouin’s gull had a narrower trophic niche (i.e. specialist behaviour), foraging exclusively at-sea, reducing the amount of demersal fish and increasing the amount of pelagic fish in their diet. Under NFA, both species foraged mostly at-sea, feeding almost exclusively on fish, with increased consumption of demersal species (i.e. fishery discards). In general, yellow-legged gull had a broader trophic niche (i.e. generalist behaviour) when compared with the narrower isotopic niche of Audouin’s gull (i.e. specialist behaviour). Overall, both gull species relied heavily on fishery discards. However, there was visible dietary, spatial, and temporal segregation between the two species, associated with their dietary and habitat preferences that could be attributed to the availability of anthropogenic resources, such as fishery discards.

scholarly journals Capelin (Mallotus villosus) distribution and climate: a sea “canary” for marine ecosystem change

2005 ◽  
Vol 62 (7) ◽  
pp. 1524-1530 ◽  
Author(s):  
G.A. Rose
Keyword(s):  
Temperature Change ◽  
North Atlantic ◽  
Marine Ecosystem ◽  
Predatory Fish ◽  
Ecosystem Change ◽  
Monitoring Methods ◽  
Mallotus Villosus ◽  
The North ◽  
Capelin Mallotus Villosus ◽  
The North Atlantic

Abstract Capelin (Mallotus villosus) is a classic “r” adapted pelagic species that inhabits the northern boreal oceans at the margins of cold Arctic waters. The species originated in the North Pacific and colonized the North Atlantic at least once during interglacial periods of the past few million years. Capelin became the main forage species for many larger predatory fish, and also for seabirds and marine mammals. The colonizing abilities of capelin have been noted in historical anecdotes, typically in concert with climate variations. In this paper, all known shifts in distribution are catalogued. Shifts have taken place at the larval and adult stages, and some result in new spawning locations, others do not. Displacement distance relates to temperature change: log10(distancekm) = 0.28 × temperature change + 2.16 (p < 0.05, r2 = 0.91). The persistence of the shifts relates to the displacement distance: log10(persistencey) = 2.62 × log10(distancekm) − 6.56 (p < 0.05, r2 = 0.83). The quick and consistent response of capelin to temperature change, its importance to the North Atlantic foodweb, and established monitoring methods suggest this species as a sea “canary” for northern boreal marine ecosystem responses to climate variability and change.

Predicted extirpation of the dominant demersal fish in a large marine ecosystem: Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence

2008 ◽  
Vol 65 (11) ◽  
pp. 2315-2319 ◽  
Author(s):  
Douglas P. Swain ◽  
Ghislain A. Chouinard
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Marine Ecosystem ◽  
Demersal Fish ◽  
Population Projections ◽  
Individual Growth ◽  
Natural Mortality ◽  
Total Allowable Catch ◽  
Spawning Stock ◽  
Large Marine Ecosystem

Atlantic cod ( Gadus morhua ) was the dominant demersal fish and most important predator in the southern Gulf of St. Lawrence ecosystem as recently as the 1980s. However, productivity of southern Gulf cod has declined, and the population is no longer viable even in the absence of fishing. We conducted population projections taking into account uncertainty in current abundance-at-age and uncertainty or variability in each of the components of population productivity (i.e., rates of recruitment, individual growth, and adult natural mortality). We defined extirpation as a spawning stock biomass less than 1000 t (<0.3% of historical levels). Based on these projections, at its current level of productivity, this population is certain to be extirpated within 40 years in the absence of fishing and in 20 years with fishery removals at the level of the total allowable catch in 2007 and 2008 (2000 t). Elevated natural mortality of adult cod (M) is the main factor contributing to the low productivity of this stock. Because M appears to be increasing, our projections are likely overly optimistic.

Trophic ecology of the mid-slope demersal fish community off southern Tasmania, Australia

2002 ◽  
Vol 53 (1) ◽  
pp. 59 ◽  
Author(s):  
C. M. Bulman ◽  
X. He ◽  
J. A. Koslow
Keyword(s):  
Fish Community ◽  
Trophic Ecology ◽  
Diet Breadth ◽  
Demersal Fish ◽  
Benthic Invertebrate ◽  
Trophic Levels ◽  
Trophic Guilds ◽  
Orange Roughy ◽  
Eastern Australia ◽  
Australasian Region

The demersal fish community on the mid-slope off southern Tasmania in south-eastern Australia is dominated by orange roughy Hoplostethus atlanticus (Trachichthyidae), several species of oreosomatids, macrourids, squalids, alepocephalids and a synaphobranchid eel. Cluster analysis based on diet dissimilarities of proportional prey weight identified five major trophic guilds: pyrosome-feeders, crustacean feeders, piscivores, benthopelagic omnivores and benthic-invertebrate feeders. Overall, the fish fed predominantly on pelagic or benthopelagic prey, consistent with other trophic studies in the Australasian region and the Northern Hemisphere. H. atlanticus, warty dory Allocyttus verrucosus, and the macrourid Coryphaenoides serrulatus were benthopelagic omnivores that ate mesopelagic fishes, crustaceans and squid. The first two species ate more mesopelagic fishes as their sizes increased. The squalids were predominantly piscivorous but might also scavenge. Macrourids were benthic-invertebrate feeders, pelagic crustacean feeders or benthopelagic omnivores. The alepocephalids and the smooth oreo Pseudocyttus maculatus were pyrosome-feeders. No seasonal variation in diet was found for any species. Ecological indices varied within each guild. Benthopelagic omnivores and piscivores had the largest diet breadth, evenness and diversity. Trophic levels ranged from 3.0 for pyrosome-feeders to 4.9 for piscivores and the overall average for the community was 3.7.

scholarly journals On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ndague Diogoul ◽  
Patrice Brehmer ◽  
Hervé Demarcq ◽  
Salaheddine El Ayoubi ◽  
Abou Thiam ◽  
...  
Keyword(s):  
Multiple Stressors ◽  
Marine Ecosystem ◽  
Trophic Levels ◽  
Sea Surface ◽  
Relative Index ◽  
Upwelling System ◽  
The North ◽  
Latitudinal Shift ◽  
Large Marine Ecosystem ◽  
North And South

AbstractThe resistance of an east border upwelling system was investigated using relative index of marine pelagic biomass estimates under a changing environment spanning 20-years in the strongly exploited southern Canary Current Large marine Ecosystem (sCCLME). We divided the sCCLME in two parts (north and south of Cap Blanc), based on oceanographic regimes. We delineated two size-based groups (“plankton” and “pelagic fish”) corresponding to lower and higher trophic levels, respectively. Over the 20-year period, all spatial remote sensing environmental variables increased significantly, except in the area south of Cap Blanc where sea surface Chlorophyll-a concentrations declined and the upwelling favorable wind was stable. Relative index of marine pelagic abundance was higher in the south area compared to the north area of Cap Blanc. No significant latitudinal shift to the mass center was detected, regardless of trophic level. Relative pelagic abundance did not change, suggesting sCCLME pelagic organisms were able to adapt to changing environmental conditions. Despite strong annual variability and the presence of major stressors (overfishing, climate change), the marine pelagic ressources, mainly fish and plankton remained relatively stable over the two decades, advancing our understanding on the resistance of this east border upwelling system.

scholarly journals Distribution of rorquals and Atlantic cod in relation to their prey in the Norwegian high Arctic

Polar Biology ◽  
2021 ◽  
Author(s):  
Hiroko K. Solvang ◽  
Tore Haug ◽  
Tor Knutsen ◽  
Harald Gjøsæter ◽  
Bjarte Bogstad ◽  
...  
Keyword(s):  
Prey Species ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Spatial Association ◽  
High Arctic ◽  
Humpback Whales ◽  
Predatory Fish ◽  
Detection Range ◽  
Minke Whales ◽  
Acoustic Methods

AbstractRecent warming in the Barents Sea has led to changes in the spatial distribution of both zooplankton and fish, with boreal communities expanding northwards. A similar northward expansion has been observed in several rorqual species that migrate into northern waters to take advantage of high summer productivity, hence feeding opportunities. Based on ecosystem surveys conducted during August–September in 2014–2017, we investigated the spatial associations among the three rorqual species of blue, fin, and common minke whales, the predatory fish Atlantic cod, and their main prey groups (zooplankton, 0-group fish, Atlantic cod, and capelin) in Arctic Ocean waters to the west and north of Svalbard. During the surveys, whale sightings were recorded by dedicated whale observers on the bridge of the vessel, whereas the distribution and abundance of cod and prey species were assessed using trawling and acoustic methods. Based on existing knowledge on the dive habits of these rorquals, we divided our analyses into two depth regions: the upper 200 m of the water column and waters below 200 m. Since humpback whales were absent in the area in 2016 and 2017, they were not included in the subsequent analyses of spatial association. No association or spatial overlap between fin and blue whales and any of the prey species investigated was found, while associations and overlaps were found between minke whales and zooplankton/0-group fish in the upper 200 m and between minke whales and Atlantic cod at depths below 200 m. A prey detection range of more than 10 km was suggested for minke whales in the upper water layers.

The summer diet of demersal fish at the South Shetland Islands

1997 ◽  
Vol 9 (4) ◽  
pp. 407-413 ◽  
Author(s):  
Masanori Takahashi ◽  
Tetsuo Iwami
Keyword(s):  
Marine Ecosystem ◽  
Stomach Contents ◽  
Demersal Fish ◽  
South Shetland Islands ◽  
Fish Prey ◽  
Shetland Islands ◽  
Antarctic Marine ◽  
Dietary Component ◽  
Gobionotothen Gibberifrons ◽  
The Antarctic

The stomach contents of demersal fish in late January 1982 were analysed. Samples were taken at 100, 300 and 500 m depth south of Elephant Island, Bransfield Strait and north of Livingston Island, and at 800 m to the east of Smith Island. Fifty four taxa of fish belonging to 11 families were collected. The diets of 2101 fish representing 38 taxa were examined. These were classified into three categories, fish feeders, krill feeders and benthos feeders. Fish prey species fed on krill and/or benthos. Krill was a major dietary component for 32 (84.2%) out of 38 taxa. Gobionotothen gibberifrons was distributed at all 10 stations (100–800 m in depth) and its diet comprised krill and benthos. The present findings verify the importance of krill in the Antarctic marine ecosystem and indicate that krill is consumed by benthic fish at greater depths than previously reported.

Sign in / Sign up

Export Citation Format

Share Document