SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Marine environmental research

25

Globally, non-native species (NNS) have been introduced and now often entirely replace native species in captive aquaculture; in part, a result of a perceived greater resilience of NSS to climate change and disease. Here, the effects of ocean acidification and warming on metabolic rate, feeding rate, and somatic growth was assessed using two co-occurring species of oysters - the introduced Pacific oyster Magallana gigas (formerly Crassostrea gigas), and native flat oyster Ostrea edulis. Biological responses to increased temperature and pCO2 combinations were tested, the effects differing between species. Metabolic rates and energetic demands of both species were increased by warming but not by elevated pCO2. While acidification and warming did not affect the clearance rate of O. edulis, M. gigas displayed a 40% decrease at 750 ppm pCO2. Similarly, the condition index of O. edulis was unaffected, but that of M. gigas was negatively impacted by warming, likely due to increased energetic demands that were not compensated for by increased feeding. These findings suggest differing stress from anthropogenic CO2 emissions between species and contrary to expectations, this was higher in introduced M. gigas than in the native O. edulis. If these laboratory findings hold true for populations in the wild, then continued CO2 emissions can be expected to adversely affect the functioning and structure of M. gigas populations with significant ecological and economic repercussions, especially for aquaculture. Our findings strengthen arguments in favour of investment in O. edulis restoration in UK waters.

25

Oil droplets may form and disperse in the water column after an accidental spill of crude oil or petroleum products at sea. Micro-sized oil droplets may be available for filter feeding organisms, such as the copepod Calanus finmarchicus, which has been shown to filter oil droplets. In the present paper, a modeling approach was used to estimate potential ingestion amounts by copepod filtration of oil droplets. The new model was implemented in the OSCAR (Oil Spill Contingency and Response) software suite, and tested for a series of oil spill scenarios and key parameters. Among these, the size of the filtered droplets was found to be the most important factor influencing the model results. Given the assumptions and simplifications of the model, filtration of dispersed crude oil by C. finmarchicus was predicted to affect the fate of 1-40% of the total released oil mass, depending on the release scenario and parameter values used, with the lower end of that range being more probable in an actual spill situation.

Concepts: Petroleum, Parameter, Exxon Valdez oil spill, Oil spill, Calanoida, Antarctic krill, Filter feeder

22

Human impact on the environment is of widespread concern. The majority of anthropogenic impacts are centred on coastal ecosystems, so surveying them is an important step in the protection of the marine environment. We have tested Oblada melanura (L. 1758) otoliths' fluctuating asymmetry as a bioindicator in a Mediterranean coastal zone. The French Riviera is characterised by a summer population increase leading in particular to more yachting, and seasonal climatic changes with reduced, more concentrated waterway flows and storm events causing soil erosion. The present three-year study compares nine sites, situated in three zones, and characterised by three types of chemical pollutant states (low; waterway mouth; recreational harbour). For O. melanura juveniles, we have not shown any significant difference in the otoliths' fluctuating symmetry between zones or types of sites. We hypothesize that high stress levels are needed to induce significant fluctuating asymmetry variation.

Concepts: Environment, Ecology, Natural environment, Climate, Ecosystem, Climate change, French Riviera, Asymmetry

16

Deep-sea hydrothermal-vent ecosystems have stimulated decades of scientific research and hold promise of mineral and genetic resources that also serve societal needs. Some endemic taxa thrive only in vent environments, and vent-associated organisms are adapted to a variety of natural disturbances, from tidal variations to earthquakes and volcanic eruptions. In this paper, physicochemical and biological impacts of a range of human activities at vents are considered. Mining is currently the only anthropogenic activity projected to have a major impact on vent ecosystems, albeit at a local scale, based on our current understanding of ecological responses to disturbance. Natural recovery from a single mining event depends on immigration and larval recruitment and colonization; understanding processes and dynamics influencing life-history stages may be a key to effective minimization and mitigation of mining impacts. Cumulative impacts on benthic communities of several mining projects in a single region, without proper management, include possible species extinctions and shifts in community structure and function.

Concepts: Biodiversity, Evolution, Biology, Ecology, Natural environment, Science, Hydrothermal vent, Volcano

11

The deep-sea environment is a sink for a wide variety of contaminants including heavy metals and organic compounds of anthropogenic origin. Life history traits of many deep-water fish species including longevity and high trophic position may predispose them to contaminant exposure and subsequent induction of pathological changes, including tumour formation. The lack of evidence for this hypothesis prompted this investigation in order to provide data on the presence of pathological changes in the liver and gonads of several deep-water fish species. Fish were obtained from the north east region of the Bay of Biscay (north east Atlantic Ocean) by trawling at depths between 700 and 1400 m. Liver and gonad samples were collected on board ship and fixed for histological processing and subsequent examination by light microscopy. Hepatocellular and nuclear pleomorphism and individual cases of ovotestis and foci of cellular alteration (FCA) were detected in black scabbardfish (Aphanopus carbo). Six cases of FCA were observed in orange roughy (Hoplostethus atlanticus) (n = 50) together with a single case of hepatocellular adenoma. A wide variety of inflammatory and degenerative lesions were found in all species examined. Deep-water fish display a range of pathologies similar to those seen in shelf-sea species used for international monitoring programmes including biological effects of contaminants. This study has confirmed the utility of health screening in deep-water fish for detecting evidence of prior exposure to contaminants and has also gained evidence of pathology potentially associated with exposure to algal toxins.

Concepts: Cancer, Biology, Pathology, Anatomical pathology, Histopathology, Atlantic Ocean, Ocean, Bay of Biscay

6

The European Union Marine Strategy Framework Directive (MSFD) requires individual member states to develop a robust set of tools for defining eleven qualitative descriptors of Good Environmental Status (GES), such as demonstrating that “Concentrations of contaminants are at levels not giving rise to pollution effects” (GES descriptor 8). Adopting the recommendations of the ICES/OSPAR Study Group for the Integrated Monitoring of Contaminants and Biological Effects (SGIMC), we present a case study demonstrating how the proposed approach, using chemical contaminant (metals and polycyclic aromatic hydrocarbons and polychlorinated biphenyls) and biological effects (EROD, bile metabolites and pathology) data in different matrices (sediment and biota), could be used to contribute to the determination of GES in a region of the North Sea region off the east coast of the UK.

Concepts: European Union, United Kingdom, Polycyclic aromatic hydrocarbon, Europe, Germany, France, Norway, North Sea

6

The taxonomic composition of biofilms on marine microplastics is widely unknown. Recent sequencing results indicate that potentially pathogenic Vibrio spp. might be present on floating microplastics. Hence, these particles might function as vectors for the dispersal of pathogens. Microplastics and water samples collected in the North and Baltic Sea were subjected to selective enrichment for pathogenic Vibrio species. Bacterial colonies were isolated from CHROMagar™Vibrio and assigned to Vibrio spp. on the species level by MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionisation - Time of Flight Mass Spectrometry). Respective polymers were identified by ATR FT-IR (Attenuated Total Reflectance Fourier Transform - Infrared Spectroscopy). We discovered potentially pathogenic Vibrio parahaemolyticus on a number of microplastic particles, e.g. polyethylene, polypropylene and polystyrene from North/Baltic Sea. This study confirms the indicated occurrence of potentially pathogenic bacteria on marine microplastics and highlights the urgent need for detailed biogeographical analyses of marine microplastics.

Concepts: Spectroscopy, Bacteria, Mass spectrometry, Microbiology, Pathogen, Fourier transform, Infrared spectroscopy, Fourier transform spectroscopy

4

Frameworks designed to prioritise the management of invasive non-native species (INNS) must consider many factors, including their impacts on native biodiversity, ecosystem services, and human health. Management feasibility should also be foremost in any prioritisation process, but is often overlooked, particularly in the marine environment. The Asian kelp, Undaria pinnatifida, is one of the most cosmopolitan marine INNS worldwide and recognised as a priority species for monitoring in the UK and elsewhere. Here, experimental monthly removals of Undaria (from 0.2 m2 patches of floating pontoon) were conducted at two marinas to investigate their influence on recruitment dynamics and the potential implications for management feasibility. Over the 18-month experiment there was no consistent reduction in Undaria recruitment following removals. Cleaning of pontoon surfaces (i.e. removal of all biota) led to significant short-term reductions in recruitment but caused a temporal shift in normal recruitment patterns. Non-selective removal (i.e. all macroalgae) generally promoted recruitment, while selective removal (i.e. Undaria only) had some limited success in reducing overall recruitment. The varied results indicate that the feasibility of limiting Undaria is likely to be very low at sites with established populations and high propagule pressure. However, where there are new incursions, a mixture of cleaning of invaded surfaces prior to normal periods of peak recruitment followed by selective removal may have some potential in limiting Undaria populations within these sites. Multi-factorial experimental manipulations such as this are useful tools for gathering quantitative evidence to support the prioritisation of management measures for marine INNS.

4

Despite its long history of hydrocarbon exploitation, the United Kingdom lacks scientific protocols to monitor ecological impacts of drill cuttings (mixtures between rocky material excavated from wells and drilling mud). The present study used the UK Benthos industry database to apply standardised variance partitioning and measure the scale and persistence of these effects at 19 sites across the UK sector of the North Sea. Generally, effects were limited to within 1 km from the platform, but two platforms historically drilled with oil-based mud were impacted up to 1.2 km away. Impacts persisted for at least 6-8 years in the northern and central North Sea, but were undetectable in the south where cuttings piles do not accumulate. This study underpins new recommendations to implement regional, phase-based approaches to drill cuttings monitoring, and to apply a precautionary approach in considering decommissioning options that will minimise disturbance to cuttings piles.

Concepts: Atlantic Ocean, United Kingdom, Europe, England, Scotland, North Sea, English Channel, North Sea oil

3

Coral reefs harbor the most diverse assemblages in the ocean, however, a large proportion of the diversity is cryptic and, therefore, undetected by standard visual census techniques. Cryptic and exposed communities differ considerably in species composition and ecological function. This study compares three different coral reef assessment protocols: i) visual benthic reef surveys: ii) visual census of Autonomous Reef Monitoring Structures (ARMS) plates; and iii) metabarcoding techniques of the ARMS (including sessile, 106-500 μm and 500-2000 μm size fractions), that target the cryptic and exposed communities of three reefs in the central Red Sea. Visual census showed a dominance of Cnidaria (Anthozoa) and Rhodophyta on the reef substrate, while Porifera, Bryozoa and Rhodophyta were the most abundant groups on the ARMS plates. Metabarcoding, targeting the 18S rRNA gene, significantly increased estimates of the species diversity (p < 0.001); revealing that Annelida were generally the dominant phyla (in terms of reads) of all fractions and reefs. Furthermore, metabarcoding detected microbial eukaryotic groups such as Syndiniophyceae, Mamiellophyceae and Bacillariophyceae as relevant components of the sessile fraction. ANOSIM analysis showed that the three reef sites showed no differences based on the visual census data. Metabarcoding showed a higher sensitivity for identifying differences between reef communities at smaller geographic scales than standard visual census techniques as significant differences in the assemblages were observed amongst the reefs. Comparison of the techniques showed no similar patterns for the visual techniques while the metabarcoding of the ARMS showed similar patterns amongst fractions. Establishing ARMS as a standard tool in reef monitoring will not only advance our understanding of local processes and ecological community response to environmental changes, as different faunal components will provide complementary information but also improve the estimates of biodiversity in coral reef benthic communities. This study lays the foundations for further studies looking at integrating traditional reef survey methodologies with complementary approaches, such as metabarcoding, which investigate other components of the reef community.

Concepts: Algae, Biodiversity, Ribosomal RNA, Coral, Coral reef, Scleractinia, Cnidaria, Red Sea