Isotopically labelled macroalgae: A new method for determining sources of excess nitrogen pollution

Climate change is increasing the frequency and magnitude of temperature anomalies that cause coral bleaching, leading to widespread mortality of stony corals that can fundamentally alter reef structure and function. However, bleaching often is spatially variable for a given heat stress event, and drivers of this heterogeneity are not well resolved. While small-scale experiments have shown that excess nitrogen can increase the susceptibility of a coral colony to bleaching, we lack evidence that heterogeneity in nitrogen pollution can shape spatial patterns of coral bleaching across a seascape. Using island-wide surveys of coral bleaching and nitrogen availability within a Bayesian hierarchical modeling framework, we tested the hypothesis that excess nitrogen interacts with temperature anomalies to alter coral bleaching for the two dominant genera of branching corals in Moorea, French Polynesia. For both coral genera, Pocillopora and Acropora, heat stress primarily drove bleaching prevalence (i.e., the proportion of colonies on a reef that bleached). In contrast, the severity of bleaching (i.e., the proportion of an individual colony that bleached) was positively associated with both heat stress and nitrogen availability for both genera. Importantly, nitrogen interacted with heat stress to increase bleaching severity up to twofold when nitrogen was high and heat stress was relatively low. Our finding that excess nitrogen can trigger severe bleaching even under relatively low heat stress implies that mitigating nutrient pollution may enhance the resilience of coral communities in the face of mounting stresses from global climate change.

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Framing nitrogen pollution in the British press: 1984–2018

Discourse & Communication ◽

10.1177/1750481319876772 ◽

2019 ◽

Vol 14 (1) ◽

pp. 84-103

Author(s):

Angela Zottola ◽

Dimitrinka Atanasova ◽

Emma Cardwell ◽

John Forrester ◽

Carly Stevens

Keyword(s):

Human Health ◽

Scientific Community ◽

Frame Analysis ◽

Active Role ◽

Nitrogen Pollution ◽

Public Understanding ◽

Government Responsibility ◽

Excess Nitrogen ◽

News Reporting ◽

British Press

Awareness of the risks posed by excess nitrogen is low beyond the scientific community. As public understanding of scientific issues is partly influenced by news reporting, this article is the first to study how the British press has discussed nitrogen pollution. A corpus-assisted frame analysis of newspaper articles (1984–2018) highlighted five frames: Activism, where environmental charities and organizations are portrayed as having an active role in fighting pollution; Government Responsibility, where privatization is presented as central and positioned as one of the main causes of pollution; Industry Responsibility, in which industries’ actions are depicted as causing pollution to increase; Pollutions as Politics, in which pollution is not discussed as a problem to be solved but rather as a means to increase votes; and Risk, where readers are warned about the possible effects of pollution on human health, flora and fauna. The analysis also points to the absence of named scientists and sources with the coverage being dominated by politicians.

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Selective Sampling and Orientation of Non-Homogeneous Tissues

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100238 ◽

1968 ◽

Vol 26 ◽

pp. 98-99

Author(s):

C. C. Clawson ◽

L. W. Anderson ◽

R. A. Good

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Light Microscopy ◽

Random Sampling ◽

New Method ◽

Microscope Examination ◽

Small Areas ◽

Selective Sampling ◽

Large Numbers ◽

Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

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