Dead Zones Discovered in Coastal Waters

Dead Zones ◽  
2021 ◽  
pp. 21-35
Author(s):  
David L. Kirchman
Keyword(s):  
North America ◽  
Gulf Of Mexico ◽  
Chesapeake Bay ◽  
Dead Zone ◽  
The Black Sea ◽  
Low Oxygen ◽  
Coastal Regions ◽  
Dead Zones ◽  
The World ◽  
The Baltic

This chapter describes the discovery of coastal dead zones, such as the Gulf of Mexico and Chesapeake Bay in North America and the Baltic and Black Seas in Europe. Gene Turner sailed out of Pascagoula, Mississippi, in the spring of 1975, on the first of seven cruises that led to the discovery of the Gulf of Mexico dead zone. In the Chesapeake Bay, an unlikely environmentalist, Charles Officer, sounded the alarm in 1984. The biggest dead zone, however, is the Baltic Sea. Even as early as 1969, ecologists feared hypoxia was turning the Baltic into a “biological desert.” The northwest shelf of the Black Sea turned hypoxic in the 1970s, which killed bottom-dwelling fish like goby and flounder. Many coastal regions around the world have low oxygen waters that devastate marine life and habitats. The early studies emphasized one or two of three ingredients—sewage, fresh water, and plant nutrients—thought to be essential in creating a dead zone. This chapter and Chapter 3 discuss these ingredients before revealing which is most important.

Coastal Dead Zones in the Past

Dead Zones ◽  
2021 ◽  
pp. 36-51
Author(s):  
David L. Kirchman
Keyword(s):  
Gulf Of Mexico ◽  
Dead Zone ◽  
Low Oxygen ◽  
Dead Zones ◽  
Oxygen Levels ◽  
The Past ◽  
Oxygen Sensitive ◽  
The Dead ◽  
The Baltic ◽  
The 19Th Century

This chapter discusses the dead zones of coastal areas: specifically the Gulf of Mexico and Europe’s Adriatic and Baltic Seas. Scientists were able to eliminate sewage from the list of ingredients that make a dead zone in the Gulf of Mexico and other coastal regions, but there was still the possibility that the loss of oxygen was natural. It wasn’t clear when the dead zone rose in the Gulf and the Baltic Sea. Systematic monitoring of dissolved oxygen in the Gulf, led by Nancy Rabalais, once called “Queen of the Dead Zone,” started only in 1986, so scientists have had to use indirect ways to deduce oxygen levels in the past. Studies using foraminifera (“forams”) and other oxygen-sensitive indices found that the proliferation of the Gulf dead zone and others started around 1950. Both the Gulf and the Baltic experienced low oxygen levels in the 19th century or earlier, but hypoxia became more common and more extensive in the middle of the 20th century.

scholarly journals Metagenomic Assembly and Prokaryotic Metagenome-Assembled Genome Sequences from the Northern Gulf of Mexico “Dead Zone”

2018 ◽  
Vol 7 (9) ◽  
Author(s):  
J. Cameron Thrash ◽  
Brett J. Baker ◽  
Kiley W. Seitz ◽  
Ben Temperton ◽  
Lauren Gillies Campbell ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Dissolved Oxygen ◽  
Dead Zone ◽  
Microbial Metabolism ◽  
Genome Sequences ◽  
Coastal Regions ◽  
Northern Gulf Of Mexico ◽  
The World ◽  
Metagenomic Assembly

Coastal regions experiencing declining dissolved oxygen are increasing in number and severity around the world. However, despite the importance of microbial metabolism in coastal hypoxia, few metagenomic surveys exist.

scholarly journals Open ocean dead zones in the tropical North Atlantic Ocean

2015 ◽  
Vol 12 (8) ◽  
pp. 2597-2605 ◽  
Author(s):  
J. Karstensen ◽  
B. Fiedler ◽  
F. Schütte ◽  
P. Brandt ◽  
A. Körtzinger ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Dead Zone ◽  
Marine Ecosystem ◽  
High Surface ◽  
Open Ocean ◽  
Depth Range ◽  
Low Oxygen ◽  
Dead Zones ◽  
Tropical North Atlantic

Abstract. Here we present first observations, from instrumentation installed on moorings and a float, of unexpectedly low (<2 μmol kg−1) oxygen environments in the open waters of the tropical North Atlantic, a region where oxygen concentration does normally not fall much below 40 μmol kg−1. The low-oxygen zones are created at shallow depth, just below the mixed layer, in the euphotic zone of cyclonic eddies and anticyclonic-modewater eddies. Both types of eddies are prone to high surface productivity. Net respiration rates for the eddies are found to be 3 to 5 times higher when compared with surrounding waters. Oxygen is lowest in the centre of the eddies, in a depth range where the swirl velocity, defining the transition between eddy and surroundings, has its maximum. It is assumed that the strong velocity at the outer rim of the eddies hampers the transport of properties across the eddies boundary and as such isolates their cores. This is supported by a remarkably stable hydrographic structure of the eddies core over periods of several months. The eddies propagate westward, at about 4 to 5 km day−1, from their generation region off the West African coast into the open ocean. High productivity and accompanying respiration, paired with sluggish exchange across the eddy boundary, create the "dead zone" inside the eddies, so far only reported for coastal areas or lakes. We observe a direct impact of the open ocean dead zones on the marine ecosystem as such that the diurnal vertical migration of zooplankton is suppressed inside the eddies.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
New Mexico ◽  
North America ◽  
Gulf Of Mexico ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Rio Grande ◽  
Large River ◽  
Freshwater Species ◽  
The World ◽  
Native Fishes

<em>Abstract.</em>—The Rio Grande is the fourth longest river in North America and the 22nd longest in the world. It begins as a cold headwater stream in Colorado, flows through New Mexico and Texas, where it becomes warm and turbid and finally empties into the Gulf of Mexico. The diversity of native fishes is high in the Rio Grande ranging from freshwater salmonids in its upper reaches to coastal forms in the lower reaches. Historically, about 40 primary freshwater species inhabited the waters of the Rio Grande. Like many rivers throughout North America, the native fish fauna of this river has been irrevocably altered. Species once present are now extinct, others are threatened or endangered, and the majority of the remaining native fishes are declining in both range and numbers. Today, 17 of the 40 primary native freshwater fishes have been either extirpated in part or throughout the Rio Grande drainage. This chapter examines the river, its fauna, and its current plight.

Liebig’s Law and Haber’s Tragedy

Dead Zones ◽  
2021 ◽  
pp. 89-105
Author(s):  
David L. Kirchman
Keyword(s):  
Gulf Of Mexico ◽  
Chesapeake Bay ◽  
19Th Century ◽  
Algal Growth ◽  
Oxygen Depletion ◽  
Nitrogen And Phosphorus ◽  
Limiting Nutrient ◽  
Von Liebig ◽  
The Baltic ◽  
Fritz Haber

The fertilizers commonly used by gardeners have many ingredients, but the biggest two are nitrogen and phosphorus, either of which can limit plant and algal growth. The idea that only one nutrient limits growth is encapsulated by Liebig’s Law of the Minimum, named after Justus von Liebig, a 19th-century German chemist. Liebig is also called the “father of fertilizer” because of his work on formulating and promulgating commercial fertilizers. However, he wasn’t the first to discover the Law, and he was wrong about the most important ingredient of fertilizers. This chapter outlines the arguments among limnologists, oceanographers, and geochemists about whether nitrogen or phosphorus sets the rate of algal growth and thus production of the organic material that drives oxygen depletion. The chapter discusses that the limiting nutrient varies with the type of aquatic habitat. In dead zones like the Gulf of Mexico, parts of the Baltic Sea, and Chesapeake Bay, bioassay experiments have shown that nitrogen is usually limiting. The nitrogen necessary for fertilizer and ammunitions comes from the Haber-Bosch process. The chapter reviews the life of one of the two German inventors, Fritz Haber, and how it was full of contradictions if not tragedy.

Demodex phocidi (Acariformes: Demodecidae) from Phoca vitulina (Carnivora: Phocidae) – the second observation in the world and a supplement to the species description

2020 ◽  
Vol 49 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Joanna N. Izdebska ◽  
Leszek Rolbiecki ◽  
Karolina Cierocka ◽  
Iwona Pawliczka
Keyword(s):  
North America ◽  
Baltic Sea ◽  
Phoca Vitulina ◽  
High Density ◽  
Species Description ◽  
The Baltic Sea ◽  
Taxonomic Description ◽  
The World ◽  
The Baltic

AbstractThe present study describes a finding of the demodecid mite Demodex phocidi in the seal Phoca vitulina in the Baltic Sea. This is the first identification in Europe and the second in the world. This is also the first observation of the Demodecidae family in the pinnipeds outside North America. A high density of demodecid mites was observed in the skin of the examined seal, but no symptoms of parasitosis were observed. Our findings also supplement the taxonomic description and morphometry of D. phocidi.

Giving the Land a Kick

Dead Zones ◽  
2021 ◽  
pp. 72-88
Author(s):  
David L. Kirchman
Keyword(s):  
Mississippi River ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Dead Zone ◽  
Direct Link ◽  
White House ◽  
Fertilizer Use ◽  
Dead Zones ◽  
The World ◽  
Excessive Nutrients

When it became clear that nutrients cause the rise of dead zones, scientists next examined the possible sources of the nutrients. This chapter argues the biggest source today is agriculture. The expansion of the Gulf of Mexico dead zone directly follows the huge increase in agricultural productivity, especially for corn. Yields increased over six times since 1930 in part because farmers used more fertilizer, “to give the land a kick.” As the chapter explains, Nancy Rabalais and Gene Turner found a direct link between fertilizer use and nutrient levels in the Mississippi River. In spite of opposition from agribusinesses, their work led to the formation of a White House committee and passage of legislation to support work on the hypoxia problem. Agriculture is also the main source of nutrients feeding dead zones in other regions of the world. The chapter later points out that the biggest user of fertilizer is now China, where excessive nutrients have caused massive harmful algal blooms and other environmental problems.

scholarly journals St. Augustinegrass for Florida Lawns

EDIS ◽  
2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Laurie E. Trenholm ◽  
Marco Schiavon ◽  
J. Bryan Unruh ◽  
Travis W. Shaddox ◽  
Kevin E. Kenworthy
Keyword(s):  
Gulf Of Mexico ◽  
The State ◽  
Coastal Regions ◽  
Stenotaphrum Secundatum ◽  
Previous Version ◽  
The World ◽  
The Mediterranean

St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze) is widely adapted to the warm, humid (subtropical) regions of the world. It is believed to be native to the coastal regions of both the Gulf of Mexico and the Mediterranean. St. Augustinegrass is the most commonly used lawn grass in Florida (Figure 1). This publication is intended for homeowners and turfgrass managers that manage St. Augustinegrass in the state of Florida. Previous version: Trenholm, Laurie, Bryan Unruh, and Travis Shaddox. 2017. “St. Augustinegrass for Florida Lawns”. EDIS 2017 (September). https://doi.org/10.32473/edis-lh010-2017.

scholarly journals Metabolic roles of uncultivated bacterioplankton lineages in the northern Gulf of Mexico “Dead Zone”

2016 ◽  
Author(s):  
J. Cameron Thrash ◽  
Kiley W. Seitz ◽  
Brett J. Baker ◽  
Ben Temperton ◽  
Lauren E. Gillies ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Algal Blooms ◽  
Dead Zone ◽  
Demersal Fish ◽  
Nitrite Reduction ◽  
Anthropogenic Activity ◽  
Metabolic Potential ◽  
Dead Zones ◽  
Northern Gulf Of Mexico ◽  
Low Do

AbstractMarine regions that have seasonal to long-term low dissolved oxygen (DO) concentrations, sometimes called ‘dead zones,’ are increasing in number and severity around the globe with deleterious effects on ecology and economics. One of the largest of these coastal dead zones occurs on the continental shelf of the northern Gulf of Mexico (nGOM), which results from eutrophication-enhanced bacterioplankton respiration and strong seasonal stratification. Previous research in this dead zone revealed the presence of multiple cosmopolitan bacterioplankton lineages that have eluded cultivation, and thus their metabolic roles in this ecosystem remain unknown. We used a coupled shotgun metagenomic and metatranscriptomic approach to determine the metabolic potential of Marine Group II Euryarchaeota, SAR406, and SAR202. We recovered multiple high-quality, nearly complete genomes from all three groups as well as those belonging to Candidate Phyla usually associated with anoxic environments-Parcubacteria (OD1) and Peregrinibacteria. Two additional groups with putative assignments to ACD39 and PAUC34f supplement the metabolic contributions by uncultivated taxa. Our results indicate active metabolism in all groups, including prevalent aerobic respiration, with concurrent expression of genes for nitrate reduction in SAR406 and SAR202, and dissimilatory nitrite reduction to ammonia and sulfur reduction by SAR406. We also report a variety of active heterotrophic carbon processing mechanisms, including degradation of complex carbohydrate compounds by SAR406, SAR202, ACD39, and PAUC34f. Together, these data help constrain the metabolic contributions from uncultivated groups in the nGOM during periods of low DO and suggest roles for these organisms in the breakdown of complex organic matter.ImportanceDead zones receive their name primarily from the reduction of eukaryotic macrobiota (demersal fish, shrimp, etc.) that are also key coastal fisheries. Excess nutrients contributed from anthropogenic activity such as fertilizer runoff result in algal blooms and therefore ample new carbon for aerobic microbial metabolism. Combined with strong stratification, microbial respiration reduces oxygen in shelf bottom waters to levels unfit for many animals (termed hypoxia). The nGOM shelf remains one of the largest eutrophication-driven hypoxic zones in the world, yet despite its potential as a model study system, the microbial metabolisms underlying and resulting from this phenomenon—many of which occur in bacterioplankton from poorly understood lineages—have received only preliminary study. Our work details the metabolic potential and gene expression activity for uncultivated lineages across several low DO sites in the nGOM, improving our understanding of the active biogeochemical cycling mediated by these “microbial dark matter” taxa during hypoxia.

What Happened in 1950?

Dead Zones ◽  
2021 ◽  
pp. 52-71
Author(s):  
David L. Kirchman
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Organic Material ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Mark Twain ◽  
Dead Zone ◽  
Algal Growth ◽  
Fish Kills ◽  
Dead Zones

This chapter discusses what happened around 1950 that led to the expansion of dead zones. For the Gulf of Mexico, there are many reasons to think the flow of the Mississippi River has changed since the days of Mark Twain, considering the construction of so many levees, dikes, floodways, spillways, weirs, and revetments. Rain-absorbing grasslands and forests have been replaced by asphalt, roof shingles, and other hydrophobic material that hasten rainwater to the Gulf. But the flow of the Mississippi has not changed enough to explain why the Gulf dead zone grew around 1950. As the chapter discusses, what did change was nutrients. It shows that concentrations doubled in the Mississippi River from the 1930s to the 1990s, which stimulated algal growth and production of organic material that eventually led to depletion of dissolved oxygen. In addition to creating dead zones, the increase in nutrients has stimulated harmful algal blooms, leading to fish kills and beach closings.

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