Icelandic Waters Research Articles

Observations of two deep-sea chimaeroids in Icelandic waters.

Long-term survey time series repeated occurrence of the deep-sea chimaeroid species small-eyed rabbitfish Hydrolagus affinis and large-eyed rabbitfish H. mirabilis have been observed at same but few locations in Icelandic waters over 23 years. For H. affinis the catch at one specific station has consisted almost exclusively of mature males over the time period. Identification of potential aggregation locations is of vital importance to natural resource management because such aggregation may render these species vulnerable to potential fishing activities.

Isolation, Characterization and Biotechnological Potentials of Thraustochytrids from Icelandic Waters.

The following study reports on the first thraustochytrid isolates identified from Iceland. They were collected from three different locations off the northern coast of the country (Location A, Skagaströnd; Location B, Hveravík; and Location C, Eyjafjörður). Using 18S rDNA sequence analysis, isolates from Locations A and B were identified within the Thraustochytrium kinnei species while other isolates within the Sicyoidochytrium minutum species when compared to other known strains. Cells isolated from Locations A ( g/L) and B ( g/L) produced more biomass than the ones isolated from Location C ( g/L). This study offers the first-time examination of the utility of byproducts from fisheries as a nitrogen source in media formulation for thraustochytrids. Experiments showed that isolates produced more biomass (per unit of substrate) when cultured on nitrogen of marine ( g/L) as compared to of commercial origin ( g/L). Glycerol ( g/L) was a better carbon source than glucose ( g/L) in growth studies. Fatty acid (FA) profiles showed that the isolates from Location C (S. minutum) had low ratios of monounsaturated () and omega-6 () FAs. However, the isolates also had high ratios of docosahexaenoic acid (DHA; ) and total omega-3 FAs (), indicating that they could serve as a source of marine oils for human consumption and in aquaculture feeds. The T. kinnei isolates from Location A could be used in biodiesel production due to their high ratios of monounsaturated () long chain () FAs.

Drivers of growth for Atlantic cod (Gadus morhua L.) in Icelandic waters - A Bayesian approach to determine spatiotemporal variation and its causes.

This study assesses spatiotemporal and sex-specific growth of Atlantic cod Gadus morhua in Icelandic waters. We use a Bayesian approach which lends itself to fitting and comparing nested models such as these. We then compare fitted parameters of these models to potential explanatory variables using a redundancy analysis (RDA) to look for drivers of growth in G. morhua. Results indicate that models that incorporate differences in growth among time, space and sex are the best-fitting models according to deviance information criterion (DIC). Results from RDA indicate that capelin Mallotus villosus recruitment and biomass is highly correlated with deviations in the von Bertalannfy growth parameter k and that L∞ is correlated with G. morhua landings in the model that uses year to account for time-varying growth and estimated G. morhua recruitment in the model that uses cohort to account for time-varying growth.

Decreased influx of Calanus spp. into the south-western Norwegian Sea since 2003

The copepods Calanus hyperboreus and C. finmarchicus are the ecologically most important copepod species in the Nordic Seas. The larger C. hyperboreus, of polar origin, is advected into the south-western Norwegian Sea with the East Icelandic Current (EIC), and can therefore be considered an indicator species of these waters. Using large spatio-temporal hydrographic and zooplankton data sets, we show that an abrupt reduction in abundance of C. hyperboreus around the year 2003 in the south-western Norwegian Sea coincided with a reduction in the volume of Modified East Icelandic Water (MEIW) in the intermediate layers (R = 0.64, lagged one year). Abundance of C. hyperboreus and the volume of MEIW have since remained lower compared to the previous years (Mann-Whitney U tests, p < 0.05). The total zooplankton biomass in spring within the EIC, east of Iceland, was also much reduced around 2003 and has also since remained low. A comparable post-2003 reduction is observed in the abundance of overwintered stages of C. finmarchicus in May. Our results suggest that the reduction of zooplankton in the south-western Norwegian Sea around 2003 was caused by reduced influence of subarctic waters from the western region. This may in turn impact the extensive feeding migration of herring to this region.

Migration pattern and evidence of homing in Atlantic wolffish (Anarhichas lupus)

Homing and site fidelity of Atlantic wolffish Anarhichas lupus was studied at the main spawning ground and four different feeding grounds in Icelandic waters. A total of 883 fish were tagged with T-bar anchor tags, whereof 349 fish also received an internally implanted data storage tag (DST). The DSTs data revealed consistent year-to-year migrations between spawning grounds and feeding grounds. Arrival time at the main spawning ground was similar for males and females, but males departed two months later, suggesting that peak of hatching of larvae was in late February. Homing was estimated to be 93% for the main spawning ground and 87% for feeding grounds. Fish tagged at the main spawning ground did not exclusively migrate to one feeding ground during the feeding season, and fish tagged at each feeding ground migrated to more than one potential spawning ground. Fish tagged at the southeast feeding ground appear to be isolated from the other areas investigated. Atlantic wolffish in Icelandic waters is currently managed as one single stock, hence the single stock management approach might need to be reconsidered.

First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 38:67-77 (2019) - DOI: https://doi.org/10.3354/esr00936 ESR Special: Marine vertebrate bycatch: problems and solutions First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters Charla J. Basran1,2,*, Chiara G. Bertulli3, Arianna Cecchetti4, Marianne H. Rasmussen2, Megan Whittaker5, Jooke Robbins6 1Department of Life and Environmental Sciences, University of Iceland, 101 Reykjavik, Iceland 2Húsavík Research Centre, University of Iceland, 640 Húsavík, Iceland 3Sea Watch Foundation, New Quay, Wales SA45 9NR, UK 4Biology Department, cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, University of the Azores, Ponta Delgada, Azores 9501-855, Portugal 5Elding Adventures at Sea, 101 Reykjavik, Iceland 6Center for Coastal Studies, Provincetown, Massachusetts 02657, USA *Corresponding author: cjb2@hi.is ABSTRACT: Entanglement in fishing gear is a significant anthropogenic source of large whale injury and mortality. Although entanglements have been reported in the eastern North Atlantic, their frequency has not been previously estimated. This study used systematic scar analysis to estimate the frequency of non-lethal entanglements among individual humpback whales Megaptera novaeangliae off coastal Iceland, from 2005 through 2017. Images of the caudal peduncle and fluke insertions of 379 individuals were analyzed for wrapping injuries and notches known to be indicative of entanglement. The results indicated that at least 24.8% (n = 94, 95% confidence intervals [95% CI]: 20.5-29.1%) of individuals had a history of prior entanglement when first encountered. Depending on the metric used, the whales subsequently acquired new entanglement-related injuries at an average rate of 1.9% (95% CI: 0.6-3.2%) or 16.3% (95% CI: 3.0-29.3%) per year, with no statistically significant change over time. Furthermore, evidence suggests that at least some entanglements occurred locally. Observations of whales with gear still entangling the body confirmed the patterns of injury studied here. These results are lower than scar-based estimates from other parts of the world, but the cause of this difference requires further study. Scar-based methods underestimate the frequency of prior entanglement because some injuries heal beyond recognition, do not involve the caudal peduncle, and may occur on whales that die before they are studied. Long-term monitoring of humpback whale entanglement in Icelandic coastal waters is important for evaluating the local effects of fisheries, as well as the viability of the endangered Cape Verde breeding population. KEY WORDS: Entanglement · Humpback whales · Scar analysis · Iceland · Megaptera novaeangliae · North Atlantic Full text in pdf format PreviousNextCite this article as: Basran CJ, Bertulli CG, Cecchetti A, Rasmussen MH, Whittaker M, Robbins J (2019) First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters. Endang Species Res 38:67-77. https://doi.org/10.3354/esr00936 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 38. Online publication date: February 07, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Tracking Holocene drift-ice limits on the northwest–southwest Iceland shelf: Comparing proxy data with observation and historical evidence

ABSTRACTWe detail variations in the weight percent (wt%) of quartz, a proxy for drift ice, in fifteen marine sediment cores from the northwest, west, and southwest Iceland shelf throughout the past 10 cal ka BP. We present the first map of iceberg distributions in Iceland waters between 1983 and 2011 and a new compilation of sea-ice records in the century from 850 to 1950 CE. The wt% of quartz, determined by quantitative X-ray diffraction (qXRD) analysis, is used to evaluate changes in the importation of drift ice. Small wt% of quartz were added to milled basalt (0% quartz), and to a mixture of non-clay and clay minerals; the qXRD method replicated 0 percent quartz, while measured 1–3 percent quartz always resulted in a “presence” estimate. The outer sites in the northwest sector lie close to the average position of the sea-ice margin between 1870 and 1920 CE; the southwest shelf sites lie south of this limit. Transects of cores along the Húnaflói and Djúpáll troughs indicate that the traces of drift ice decrease rapidly landward from the outer sites. The cores from the west/southwest of Iceland have limited amounts of quartz, generally possibly limited incursions of drift ice.

O, H and C isotopic systematics of Icelandic groundwater

Stable water isotopes of oxygen and hydrogen have been studied in Icelandic natural waters since 1960 for hydrological and geothermal research. All the waters are of meteoric and seawater origin. The measured range in δD and δ18O is large -131 to +3.3‰ and -20.8 to +2.3‰ respectively. Some of the waters are more depleted than any present-day precipitation suggesting a pre-Holocene component in the groundwater. Carbon isotopes of streams, rivers, soil and groundwater have been studied since 1990 in order to evaluate the carbon sources and reactions that possibly influence the carbon systematics of the water. Results show large range of values, for δ13CDIC -27.4 to +4.5‰ and for 14CDIC +0.6 to +118 pMC. Apart from atmospheric, organic and rock leaching, input of gas at depth with similar isotopic composition as the pre-erupted melt of the upper mantle and lower crust beneath Iceland have been identified as sources for carbon in the deeper groundwater.

Exploring the effects of discarding using the Atlantis ecosystem model for Icelandic waters

Discarding fish has been a part of the fisheries for centuries but it has been very difficult to monitor how much is discarded, especially in areas where it is an illegal activity. In this study the ecological and economic effects of discarding were investigated using the Atlantis model for Icelandic waters. Five different scenarios were compared, using different discarding rates and selectivities. The results showed that a complete stop of discarding fish (cod and haddock) and landing everything instead had little ecological and economic impact. Improved selectivity, which would result in not catching the fish that would be discarded, had great beneficial economic effects. The increase in biomass led to higher landings, which consequently led to higher revenue. Also, the cost decreased with increasing biomass, which increased the profit of the fisheries. None of the five scenarios had great ecological effects but only discarding of cod and haddock, which have low discard rates, were considered in this study.

Prey of killer whales (Orcinus orca) in Iceland.

Killer whales have a cosmopolitan distribution and as a species are generalists, feeding on a variety of prey. However, local populations tend to specialise on specific prey types. In Icelandic waters, killer whales are generally associated with herring and, thus, have been presumed to be herring specialists. However, recent studies suggest a more complex foraging ecology, possibly including a mosaic of strategies. With increased observational effort in recent years due to research and whale-watching activities, there have been several reports of interactions with different prey, including confirmed predation events. In this study we aimed to summarise the range of potential prey of killer whales observed in Icelandic waters. We report on 12 previously unpublished accounts and review 15 accounts published in the scientific literature or local newspapers, making a total of 27 events where killer whales were observed interacting with actual or potential prey. Thirteen different species, including birds (n = 1), cephalopods (n = 1), fish (n = 5) and marine mammals (n = 6), are reported, although herring is by far the species that killer whales are most often observed interacting with. This study provides the first summary of actual and suspected killer whale prey in Icelandic waters, and contributes towards our understanding of this population’s prey preferences. However, describing the diet of individuals/groups was not possible and this study points to a need for continued monitoring to understand the intricacies of killer whale foraging behaviour in this area.

What happened in the mid-1990s? The coupled ocean-atmosphere processes behind climate-induced ecosystem changes in the Northeast Atlantic and the Mediterranean

Northeast Atlantic marine ecosystems such as the Bay of Biscay, Celtic Sea, English Channel, Subpolar Gyre region, Icelandic waters and North Sea as well as the Mediterranean Sea show concomitant ‘regime shift’-like changes around the mid-1990s, which involved all biota of the pelagial: phytoplankton, zooplankton, pelagic fish assemblages, demersal fish assemblages and top predators. These shifts were caused by complex ocean-atmosphere interactions initiating large-scale changes in the strength and direction of the current systems, that move water masses around the North Atlantic, and involved the North Atlantic Oscillation (NAO), the Atlantic Meridional Overturning Circulation (AMOC), and the subpolar gyre (SPG). The contractions and expansions of the SPG and fluctuations of the Atlantic Multidecadal Oscillation (AMO) play a key role in these complex processes. Small pelagic fish population trends were the sentinels of these changes in the mid-1990s in the ecosystems under investigation.

Bacterial diversity in the marine sponge Halichondria panicea from Icelandic waters and host-specificity of its dominant symbiont "Candidatus Halichondribacter symbioticus".

Marine sponges can harbour diverse bacteria that contribute to host metabolism and defence. Identifying these stable members of sponge bacterial communities remains a necessary step in understanding their ecological roles and underlying co-evolutionary processes. In this study, we applied high-throughput sequencing of 16S rRNA gene amplicons, ribosomal nucleotide variant analysis and fluorescence in situ hybridisation to characterise the core members of the bacterial community in the marine sponge Halichondria panicea from Icelandic waters. We show that the core bacterial community across all samples consisted of a single, dominant bacterial taxon, for which we propose a candidate status 'Candidatus Halichondribacter symbioticus'. Comparison against public databases showed that 'Ca. H. symbioticus' is both a highly abundant specialist in H. panicea and a low abundant opportunist in other sponge species. Additionally, H. panicea with and without 'Ca. H. symbioticus' co-exist in similar locations in the North Atlantic. This dichotomy paired with the presence of geographically distinct ribosomal sequence variants of the symbiont make H. panicea an interesting sponge species for studying sponge-symbiont co-evolution and functional interactions.

Comparing the steady state results of a range of multispecies models between and across geographical areas by the use of the jacobian matrix of yield on fishing mortality rate

Like other fisheries models, multispecies models are subject to various sources of error. However, with regard to their use for ecosystem-based fisheries management (EBFM) between model errors are likely to be most important. As multispecies models are by definition many-dimensional, comparing them is potentially a complex task. The paper uses a simple approach. This is to calculate the Jacobian matrix of long term steady state catch by species with respect to the fishing mortality relative to status quo levels on all species. This enables the comparison of the relative strength of species interactions among models both within and between regions. This Jacobian matrix approach to comparing multispecies models is applied to available models for the North Sea, the Baltic Sea and from Icelandic waters. Moreover, this information is used to provide the basis for estimating a multidimensional quadratic yield surface for each model in the near field. Used this way it is possible to compare different model estimations of fishing mortality rate changes needed to approach yield-related management goals. The results suggest considerable variation between models in their detailed results but more coherence in suggesting directions for changing fishing mortality rate. Thus the approach is of considerable importance in specifying the confidence with which it is possible to make multispecies predictions for EBFM.

The existence and population connectivity of Icelandic spring-spawning herring over a 50-year collapse period

Abstract In the late 1960s, two local herring stocks and one seasonal migratory herring stock in Icelandic waters collapsed primarily due to overfishing. While the stocks of Icelandic summer-spawning herring (ISSH) and Norwegian spring-spawning herring (NSSH) have recovered, Icelandic spring-spawning herring (ISPH) has not. The main objective of this work is to explore the existence of ISPH and identify potential signs of recovery. Analyses were based on samples from the autumn fishery and survey data from 1962 to 2016. In the autumn, local ISSH and ISPH cohabitated and mixed in the main fishery, where sampled fish were categorized into stocks on basis of maturity stage. The results indicate that the proportion of ISPH was in the range of 13–33% in the 1960s while below 5% and on average 1.4% during 1970–2016. Several year classes of ISPH exhibit notable differences from the general low levels and caused a slight increase in ISPH spawning-stock biomass for corresponding years. An increase in proportion of generally old ISPH around 2004 and 2013 occurred simultaneously with the reappearances of NSSH in the feeding areas east and north of Iceland, respectively. Altogether, it supports earlier suggestions that ISPH might require immigration from NSSH to recover, as these were considered closely related stocks. This is consistent with the source-sink theoretical model of stock size regulation.

Pushing the limits of a data challenged stock: A size- and age-structured assessment of ling (Molva molva) in Icelandic waters using Gadget

In recent years a greater emphasis has been placed on developing management strategies that prevent over-exploitation. Harvest control rules (HCRs) have therefore, in many places, been developed and implemented. Commonly these HCRs are developed for stocks that are assessed using age-structured models, and various platforms exist to evaluate their performance and analyze various sources of bias for that particular class of models. Many stocks, however, cannot be assessed reliably using classical age-structured methods due to data limitations (gaps in data series, unreliable age readings, etc.). One such stock is the common ling (Molva molva) in Icelandic waters. Availability of data on the stock dynamics, in particular age data for both survey and commercial samples, has been a limiting factor when assessing the stock. When modeling stocks such as this, data limitations need to be considered, and how associated uncertainty is propagated both through the assessment and into the advice. In this study, ling was assessed using the size- and age-structured model Gadget after synthesizing all available data. Having limited age data available causes high uncertainty in the model fitting process, especially in estimating growth. However, including this key uncertainty in the assessment allowed the subsequent management strategy evaluation to take it into account directly while deriving common management reference points and estimating uncertainties in stock status and other derived quantities. Uncertainty was estimated using a specialized bootstrap for disparate data sets that mimics the sampling process. The process of assimilating data for the assessment model and the bootstrap procedure was performed using a specialized database program, MFDB, ensuring that the whole process is reproducible.

End-to-end model of Icelandic waters using the Atlantis framework: Exploring system dynamics and model reliability

Icelandic waters are very productive and the fisheries are economically important for the Icelandic nation. The importance of the fisheries has led to progressive fisheries management and extensive monitoring of the ecosystem. However, fisheries management is mainly built on single species stock assessment models, and multi-species or ecological models are essential for building capacity around ecosystem-based fisheries management. This paper describes the first end-to-end model for the Icelandic waters using the Atlantis modeling framework. The modeled area is 1,600,000 km2, and covers the area from Greenland through Icelandic waters to the Faroe Islands. The ocean area was divided into 51 spatial boxes, each with multiple vertical layers. There were 52 functional groups in the model: 20 fish groups (8 at a species level), 5 groups of mammals, 1 seabird group, 16 invertebrates, 5 primary producers, 2 bacteria and 3 detritus groups. The reliability of the model was evaluated using a skill assessment and a sensitivity analysis was conducted to understand the dynamics of the system. The sensitivity study revealed that saithe, redfish and tooth whales had the greatest effect on other groups in the system. The skill assessment showed that the model was able to replicate time-series of biomass and landings for the most important commercial groups and that modeling of the recruitment processes was important for some of the groups. This model now provides a solid basis for evaluating alternative ecosystem and fisheries management scenarios, and should produce reliable results for the most important commercial groups.

Predictive models using randomForest regression for distribution patterns of meiofauna in Icelandic waters

The exchange of cold polar waters from the north and warm North Atlantic waters from the south is limited by the Greenland-Iceland-Scotland Ridge (GSR) which then may act as a barrier for faunal exchange from the deep Artic and deep Atlantic basins. We investigated the meiofauna density and distribution patterns from different regions north and south of the GSR at water depths between 307 and 2749 m. A total of 84 multicore samples were examined collected during the IceAGE1 (Icelandic marine Animals: Genetics and Ecology) project in summer 2011. We used a gradientForest approach to assess the magnitude of compositional change and the thresholds of remarkable community changes along environmental variables. randomForest regression was applied to predict the meiofauna on a spatial contiguous scale with a set of 23 environmental variables. Meiofauna density ranged between 187 and 3185 individuals per 10 cm2 with the highest densities observed north of the GSR. Nematoda was the most abundant taxon among the meiofauna community, followed by Copepoda and Nauplii. In the Irminger Basin, Gastrotricha was the third most abundant taxon, while in all other regions, Ostracoda was the third most abundant. Food supply, water depth, bottom water oxygen, and hydrographic activity being the most important variables for community changes explain up to 86% of the variation observed in the meiofauna communities.

Hidden diversity in two species complexes of munnopsid isopods (Crustacea) at the transition between the northernmost North Atlantic and the Nordic Seas

Eurycope producta Sars, 1868 and Eurycope inermis Hansen, 1916 are two widely distributed and highly abundant isopod species complexes within Icelandic waters, a region known for its highly variable environment. The two species complexes have bathymetric depth ranges from 103 to 2029 m (E. producta) and from 302 to 2113 m (E. inermis). Molecular evidence was used for species delimitation within these species complexes by analyzing nuclear (18S rDNA, H3) and mitochondrial (16S rDNA, COI) sequence data. Tree-based methods (BI and ML) and four species delimitation methods (ABGD, GMYC, NDT, PTP) were applied, in order to disentangle the two species complexes. A total of eight and four species clades could be identified within samples of the E. producta and E. inermis complexes and respectively included the closely related species E. dahli Svavarsson, 1987; E. hanseni Ohlin, 1901; and E. cornuta Sars, 1864. The morphological findings coincide with the observed molecular species clades. The elucidated species clades were geographically and bathymetrically much more restricted than previously assumed. Eight species clades featured depth spans of less than 400 m and only four species clades featured depth spans of 1000 to 1500 m. Only two species clades (E. producta sensu stricto and E. inermis sensu stricto) were found on both sides of the Greenland-Scotland Ridge. Further, species distribution maps were generated using random forest, to predict potential distributional patterns for the resolved species clades of the two species complexes. We present the first attempt of combining morphological, molecular, and species distribution models in marine isopods thus far.

Preface—biodiversity of Icelandic waters

Preface—biodiversity of Icelandic waters

Biogeographic distributions of Cytheropteron species (Ostracoda) in Icelandic waters (sub-polar North Atlantic)

The ostracod genus Cytheropteron (Ostracoda: Crustacea) has been widely used for paleoenvironmental, paleoceanographic, and paleobiogeographic studies. But species-level data remain limited, especially for deepwater species. Here, we show the depth and spatial distribution patterns of 33 species of the ostracod genus Cytheropteron found in recent surface sediments of Icelandic waters. Species-specific depth ranges may serve as a useful tool in ostracod-based paleoenvironmental reconstruction. Biogeographic distributions of Cytheropteron species indicate the shallow Greenland-Iceland-Faroe Ridge as the major barrier for the distribution of deep-sea organisms.