Pelagic denitrification and methane oxidation in oxygen-depleted waters of the Louisiana shelf

Anthropogenic nutrient inputs fuel eutrophication and hypoxia ([O₂]?<?2 mg L^?1), threatening coastal and near shore environments across the globe. The world’s second largest anthropogenic coastal hypoxic zone occurs annually along the Louisiana (LA) shelf. Springtime loading of dissolved inorganic nitrogen (DIN) from the Mississippi River, combined with summertime stratification and increased water residence time on the shelf, promotes establishment of an extensive hypoxic zone that persists throughout the summer. We investigated the patterns of pelagic denitrification and methane (CH₄) oxidation along the LA shelf. Microbial activity rates were determined along with concentrations of dissolved nutrients and greenhouse gases, nitrous oxide (N₂O) and CH₄, during summer in 2013, 2015, and 2016. We documented denitrification rates up to 1900 nmol N L^?1 d^?1 and CH₄ oxidation rates as high as 192 nmol L^?1 d^?1 in hypoxic waters characterized by high concentrations of N₂O (range: 1 to 102 nM) and CH₄ (range: 3 to 641 nM). Ecosystem scaling estimates suggest that pelagic denitrification could remove between 0.1 and 47% of the DIN input from the Mississippi River, whereas CH₄ oxidation does not function as an effective removal process with CH₄ escaping to the atmosphere. Denitrification and CH₄ oxidizing bacteria within the LA shelf hypoxic zone were largely unable to keep up with the DIN and CH₄ inputs to the water column. Rates were variable and physiochemical dynamics appeared to regulate the microbial removal capacity for both nitrate/nitrite and CH₄ in this ecosystem.

     

In-Water Bridge Construction Effects on Manatees with Implications for Marine Megafauna Species

Globally, increasing coastal development requires construction and maintenance of transportation infrastructure that affects terrestrial and aquatic ecosystems. Construction of bridges as part of transportation networks introduces a series of risks to aquatic species near construction zones. We reviewed relevant literature and obtained exemplary case studies to synthesize potential effects of bridge construction on the West Indian manatee (Trichechus manatus), a nearshore megafauna species vulnerable to human activities. Stages of bridge construction including dredging, pile driving, and installation and assembly of bridge components each involve potential direct and indirect effects on manatees. Direct effects such as vessel interactions, entanglement or ingestion, and entrainment may result in acute physical injury or mortality. Indirect effects from construction such as habitat obstruction or degradation and increased noise from construction activities can alter behavior and intraspecies communication and reduce access to essential resources. Some effects of construction may be immediately difficult to quantify, but cumulative effects through time can result in major habitat and species loss. To prevent large-scale negative effects of construction on manatees and other aquatic species, use and evaluation of mitigation strategies should be implemented pre-, during, and post-construction. As the global human population increasingly occupies coastal zones, effective planning of coastal development, including bridge and other in-water construction, will be essential to support conservation and recovery efforts for manatees and other species at risk in these areas. © 2021 The Wildlife Society.     

Crabby commotions: visual not vibrational-orientated searching behaviours guide aggregation formation around key resources

Journal of Ethology - Incidental stimuli produced by animal aggregations may be utilised by conspecifics to locate key resources in areas, where resources are patchily distributed and temporally...     

<Emphasis Type="Italic">Vive la différence</Emphasis>: naming structural variants in the human reference genome

The HUGO Gene Nomenclature Committee has approved gene symbols for the majority of protein-coding genes on the human reference genome. To adequately represent regions of complex structural variation, the Genome Reference Consortium now includes alternative representations of some of these regions as part of the reference genome. Here, we describe examples of how we name novel genes in these regions and how this nomenclature is displayed on our website, http://genenames.org.     

Note: A Convenient Method for the Preparation of N2, N2-Dimethylguanosine

Abstract

The preparation of N², N²-dimethylguanosine is described. The use of the 2-(p-nitrophenyl)ethyl group instead of the benzyl protecting group for the O⁶ position of the guanine ring resulted in better yields and shorter protocols.     

Qualitative veterinary risk assessment of the role of wild deer in the likelihood of incursion and the impact on effective disease control of selected exotic notifiable diseases in England

A qualitative risk assessment was undertaken to analyse the likelihood of the incursion of selected exotic infectious disease into deer populations in GB and the potential impacts these animals could have on effective disease control. In order to identify the exposure pathways, it was necessary to consider not only the epidemiology of the pathogens but also to understand the impact of the ecology and behaviour of wild deer on disease transmission. It was concluded that the greatest risk of exotic disease incursion into wild deer in GB was disease incursions occurring in domestic ruminants first then transmitting to wild deer. The qualitative risk assessment considered geographic spread and habitats of wild deer and the susceptibility of wild deer to notifiable exotic diseases of domestic ruminants. Data of some diseases in some deer species is limited and the overall assessment of impact varied between diseases and deer species. Red deer pose the highest risk of the species reviewed. The overall risk assessment of low is primarily influenced by the low risk of incursion of exotic diseases generally into the UK.