Endangered right whales enhance primary productivity in the bay of fundy

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Marine mammals have recently been documented as important facilitators of rapid and efficient nutrient recycling in coastal and offshore waters. Whales enhance phytoplankton nutrition by releasing fecal plumes near the surface after feeding and by migrating from highly productive, high-latitude feeding areas to low-latitude nutrient-poor calving areas. In this study, we measured NH4 + and PO4 3- release rates from the feces of North Atlantic right whales (Eubalaena glacialis), a highly endangered baleen whale. Samples for this species were primarily collected by locating aggregations of whales in surface- Active groups (SAGs), which typically consist of a central female surrounded by males competing for sexual activity. When freshly collected feces were incubated in seawater, high initial rates of N release were generally observed, which decreased to near zero within 24 hours of sampling, a pattern that is consistent with the active role of gut microflora on fecal particles. We estimate that at least 10% of particulate N in whale feces becomes available as NH4 + within 24 hours of defecation. Phosphorous was also abundant in fecal samples: Initial release rates of PO4 3- were higher than for NH4 +, yielding low N/P nutrient ratios over the course of our experiments. The rate of PO4 3- release was thus more than sufficient to preclude the possibility that nitrogenous nutrients supplied by whales would lead to phytoplankton production limited by P availability. Phytoplankton growth experiments indicated that NH4 + released from whale feces enhance productivity, as would be expected, with no evidence that fecal metabolites suppress growth. Although North Atlantic right whales are currently rare (approximately 450 individuals), they once numbered about 14,000 and likely played a substantial role in recycling nutrients in areas where they gathered to feed and mate. Even though the NH4 + released from fresh whale fecal material is a small fraction of total whale fecal nitrogen, and recognizing the fact that the additional nitrogen released in whale urine would be difficult to measure in a field study, the results of this study support the idea that the distinctive isotopic signature of the released NH4 + could be used to provide a conservative estimate of the contribution of the whale pump to primary productivity in coastal regions where whales congregate

Monitoring and modelling marine zooplankton in a changing climate

Zooplankton are major consumers of phytoplankton primary production in marine ecosystems. As such, they represent a critical link for energy and matter transfer between phytoplankton and bacterioplankton to higher trophic levels and play an important role in global biogeochemical cycles. In this Review, we discuss key responses of zooplankton to ocean warming, including shifts in phenology, range, and body size, and assess the implications to the biological carbon pump and interactions with higher trophic levels. Our synthesis highlights key knowledge gaps and geographic gaps in monitoring coverage that need to be urgently addressed. We also discuss an integrated sampling approach that combines traditional and novel techniques to improve zooplankton observation for the benefit of monitoring zooplankton populations and modelling future scenarios under global changes

Sea ice meltwater and circumpolar deep water drive contrasting productivity in three Antarctic polynyas

In the Southern Ocean, polynyas exhibit enhanced rates of primary productivity and represent large seasonal sinks for atmospheric CO2. Three contrasting east Antarctic polynyas were visited in late December to early January 2017: the Dalton, Mertz, and Ninnis polynyas. In the Mertz and Ninnis polynyas, phytoplankton biomass (average of 322 and 354 mg chlorophyll a (Chl a)/m2, respectively) and net community production (5.3 and 4.6 mol C/m2, respectively) were approximately 3 times those measured in the Dalton polynya (average of 122 mg Chl a/m2 and 1.8 mol C/m2). Phytoplankton communities also differed between the polynyas. Diatoms were thriving in the Mertz and Ninnis polynyas but not in the Dalton polynya, where Phaeocystis antarctica dominated. These strong regional differences were explored using physiological, biological, and physical parameters. The most likely drivers of the observed higher productivity in the Mertz and Ninnis were the relatively shallow inflow of iron‐rich modified Circumpolar Deep Water onto the shelf as well as a very large sea ice meltwater contribution. The productivity contrast between the three polynyas could not be explained by (1) the input of glacial meltwater, (2) the presence of Ice Shelf Water, or (3) stratification of the mixed layer. Our results show that physical drivers regulate the productivity of polynyas, suggesting that the response of biological productivity and carbon export to future change will vary among polynyas

The importance of Antarctic krill in biogeochemical cycles

Antarctic krill (Euphausia superba) are swarming, oceanic crustaceans, up to two inches long, and best known as prey for whales and penguins – but they have another important role. With their large size, high biomass and daily vertical migrations they transport and transform essential nutrients, stimulate primary productivity and influence the carbon sink. Antarctic krill are also fished by the Southern Ocean’s largest fishery. Yet how krill fishing impacts nutrient fertilisation and the carbon sink in the Southern Ocean is poorly understood. Our synthesis shows fishery management should consider the influential biogeochemical role of both adult and larval Antarctic krill

One hundred priority questions for advancing seagrass conservation in Europe

17 pages, 2 figures.-- Open AccessSeagrass meadows provide numerous ecosystem services including biodiversity, coastal protection, and carbon sequestration. In Europe, seagrasses can be found in shallow sheltered waters along coastlines, in estuaries & lagoons, and around islands, but their distribution has declined. Factors such as poor water quality, coastal modification, mechanical damage, overfishing, land-sea interactions, climate change and disease have reduced the coverage of Europe’s seagrasses necessitating their recovery. Research, monitoring and conservation efforts on seagrass ecosystems in Europe are mostly uncoordinated and biased towards certain species and regions, resulting in inadequate delivery of critical information for their management. Here, we aim to identify the 100 priority questions, that if addressed would strongly advance seagrass monitoring, research and conservation in Europe. Using a Delphi method, researchers, practitioners, and policymakers with seagrass experience from across Europe and with diverse seagrass expertise participated in the process that involved the formulation of research questions, a voting process and an online workshop to identify the final list of the 100 questions. The final list of questions covers areas across nine themes: Biodiversity & Ecology; Ecosystem services; Blue carbon; Fishery support; Drivers, Threats, Resilience & Response; Monitoring & Assessment; Conservation & Restoration; Governance, Policy & Management; and Communication. Answering these questions will fill current knowledge gaps and place European seagrass onto a positive trajectory of recoveryThis project was initiated and carried out under the EuroSea project using funding from the United Nations Educational, Scientific and Cultural Oragnisation. Additional support was from the UK Natural Environment Research Council RESOW grant to Swansea University (NE/V016385/1). The EuroSea project is funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 862626. Thanks to Toste Tanhua and Emma Heslop for their supporting this process. Thanks are due to FCT/MCTES for the financial support to CESAM (UIDB/50017/2020 + UIDP/50017/2020 + LA/P/0094/2020), through PT national funds. Financial support from Fundacao para a Ciencia e a Technologia was also provided through the research contract to A.I. Sousa (CEECIND/00962/2017)Peer reviewe

Effects of exotic riparian vegetation on leaf breakdown by shredders: a tropical-temperate comparison

Displacement of riparian vegetation by exotic species is a global phenomenon with the potential to affect leaf breakdown rates by shredders. We predicted that exotic riparian vegetation would have a greater effect on leaf breakdown by temperate than by tropical shredders because temperate shredders usually feed on a limited range of generally palatable leaves, whereas tropical shredders are naturally exposed to a higher variety of leaves, many of them unpalatable. We tested 3 hypotheses with common shredder assemblages from tropical Queensland and temperate Tasmania (Australia): 1) tropical shredders are equally efficient at breaking down native and exotic vegetation, whereas temperate shredders are less efficient at breaking down exotic vegetation; 2) tropical shredders are more generalist in their leaf choices than temperate shredders; and 3) shredders are more generalist in their leaf choices among exotic than among native vegetation. Hypothesis 1 was not supported. Caddisflies (tropical or temperate) were able to consume both native and exotic leaves, whereas non-caddisfly shredders fed only on native leaves, a result suggesting that shredding capacity depends on the identity of the shredder species or their phylogenetic position rather than on their origin. Hypothesis 2 was supported. Tropical shredders fed on various leaf types, whereas most temperate shredders chose one leaf type and fed on it for the duration of the experiment. Hypothesis 3 was not supported. Specificity of shredder choices did not differ between native and exotic leaves, a result suggesting that shredding behavior is not flexible, regardless of the leaf litter available. Thus, invasive riparian plants may affect leaf breakdown by shredders, particularly in temperate streams, but effects may vary depending on assemblage composition, the nature and timing of litterfall, and interactions with climate.Peer Reviewe

Rapid Prototyping of Clarkson’s Lattice Reduction for MIMO Detection

Abstract—This paper presents the field-programmable gate array (FPGA) implementation of a variant of the Lenstra-Lenstra-Lovász (LLL) lattice reduction (LR) algorithm, known as the Clarkson’s Algorithm (CA), and its application to uncoded multiple input-multiple output (MIMO) detection. The CA provides practically the same performance as the LLL algorithm while having a considerably lower complexity, especially for MIMO systems with a large number of transmit and receive antennas. The algorithm has been implemented in real-time using a rapid prototyping methodology, greatly reducing its development time. Implementation results indicate that the variable complexity and the sequential nature of LR algorithms, like the CA, remain their main drawbacks from an implementation point of view. Index Terms—MIMO, lattice reduction, rapid prototyping. I