scholarly journals Historical Shifts in Benthic Infaunal Diversity in the Northern Gulf of Mexico since the Appearance of Seasonally Severe Hypoxia

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 49
Author(s):  
Nancy N. Rabalais ◽  
Melissa M. Baustian
Keyword(s):  
Species Richness ◽  
Dissolved Oxygen ◽  
Bottom Water ◽  
Benthic Communities ◽  
Penaeid Shrimp ◽  
Severe Hypoxia ◽  
Low Oxygen ◽  
Large Area ◽  
Surface Deposit ◽  
Deposit Feeders

Severe and persistent bottom-water hypoxia (≤2 mg O2 L−1) occurs on the Louisiana/Texas continental shelf from mid-May through mid-September over a large area (up to 23,000 km2 in mid-summer). Benthic infauna are less mobile than demersal organisms and become stressed by the low dissolved oxygen; benthic community composition, abundance, diversity, and biomass become altered. From the 1950s to the early 1970s, when sediment core indicators identified the initiation and subsequent worsening of dissolved oxygen conditions, there were no hydrographic data or benthic infaunal studies within the current area of frequent bottom-water hypoxia. This study highlights the impacts of severe hypoxia on benthic macroinfaunal communities and how they may have changed from less-hypoxic periods. Polychaetes were and are the dominant taxa in the available studies, but polychaete species richness in summer is now curtailed severely beginning with our 1985–1986 data. Species richness of polychaetes in summer hypoxia (1985–1986 and 1990–1991) was about 60% less than comparable taxa in 1972–1973. Abundance of polychaetes was much less in summer than spring, and recent infaunal biomass in summer was only 15% of what was found in spring. The result is less prey for demersal penaeid shrimp and fishes. Over the period of our comparison, infaunal feeding modes shifted from subsurface deposit feeders and surface deposit feeders to primarily surface deposit feeders (i.e., 95.5% of all polychaetes). Most were opportunistic, hypoxia tolerant, and recruited in high numbers following hypoxia abatement, some in fall and winter but most in spring. As benthic communities succumb to the stress of severe and continued seasonal low oxygen, they occupy the few upper centimeters of the sediment profile above the redox discontinuity layer with negative feedbacks to the water column by way of altered biogeochemical processes.

Infaunal benthic community structure and function in the Gulf of Carpentaria, northern Australia

1994 ◽  
Vol 45 (3) ◽  
pp. 293 ◽  
Author(s):  
BG Long ◽  
IR Poiner
Keyword(s):  
Species Richness ◽  
Species Density ◽  
Physical Factors ◽  
Suspension Feeding ◽  
Sediment Texture ◽  
Surface Deposit ◽  
Feeding Mode ◽  
Sediment Grain Size ◽  
South Eastern ◽  
Deposit Feeders

The infaunal benthos (>20 m) of the Gulf of Carpentaria was surveyed during November and December 1990. In all, 684 taxa were collected from 105 stations, each with three replicate 0.1-m2 grab samples (Smith-McIntyre grab). Trends in abundance and species richness were correlated with gulf-wide trends in sediment texture and depth. Highest abundance (20-153 individuals per 0.1 m2), wet-weight biomass (X=7.6 g per 0.1 m2) and species density (X=25.8 taxa per 0.1 m2) occurred in the sands and muddy sands along the eastern and south-eastern margins of the gulf. Lowest abundance (3.3-20.0 individuals per 0.1 m2), biomass (X=3.0 g per 0.1 m2) and species density (X=9.5 taxa per 0.1 m2) occurred in the muds and sandy muds in the centra, western and north-western gulf. Infaunal abundance and biomass were similar to those of other tropical continental shelves but were lower than those of some temperate-region shelves and upwelling areas. Species richness was also lower than in temperate areas of upwelling or high production. Scavengers/carnivores (44%) and deposit feeders (43%) numerically dominated throughout the gulf. Suspension feeding was less prevalent (13%), and few herbivores were found (< 1%). There was a trend in the proportion of deposit and suspension feeders that was related to sediment texture. Suspension feeding was highest in the muddy sands of the eastern and south-eastern gulf and lowest in the muds of the north-west. The proportion of deposit feeders was highest in muddy sediments and lowest in sandy sediments. Small (<5 mm) surface deposit feeders numerically dominated within this feeding mode. The 15 numerically dominant taxa were comprised mainly of opportunistic or second-stage colonizing taxa. Most had gulf-wide distribution patterns, but levels of abundance were correlated with sediment and depth. The infaunal benthic communities in the Gulf of Carpentaria appear to be regulated by physical factors of the environment that correlate with sediment grain size and depth.

scholarly journals Mg/Ca and Mn/Ca ratios in benthic foraminifera: the potential to reconstruct past variations in temperature and hypoxia in shelf regions

2013 ◽  
Vol 10 (7) ◽  
pp. 5125-5138 ◽  
Author(s):  
J. Groeneveld ◽  
H. L. Filipsson
Keyword(s):  
Dissolved Oxygen ◽  
Trace Metal ◽  
Benthic Foraminifera ◽  
Bottom Water ◽  
Oxygen Depletion ◽  
Open Ocean ◽  
Low Oxygen ◽  
Saturation State ◽  
Bottom Water Temperature ◽  
Fish And Shellfish

Abstract. Shelf and coastal regions are exceptionally important for many countries as they provide the main habitat for many economically important fish and shellfish species. With ongoing climate change and human-induced eutrophication the shelf regions are especially affected, resulting in increased temperatures and stratification as well as oxygen depletion of the bottom waters. In order to be able to predict the magnitude of these changes in the future, it is necessary to study how they varied in the past. Commonly used foraminiferal climate and environmental proxies, e.g., stable isotopes and trace metal/Ca ratios, that are applied in open-ocean settings are not necessarily applicable in shelf regions, either as faunas are significantly different or as conditions can change much faster compared to the open ocean. In this study we explore the use of Mg/Ca as paleothermometer and Mn/Ca as a potential proxy for changing dissolved oxygen conditions in bottom water on the benthic foraminifera Bulimina marginata and Globobulimina turgida. Living specimens were collected from the Skagerrak and the Gullmar Fjord (SW Sweden); the latter is hypoxic for several months a year. As the specimens were alive when collected, we assume it unlikely that any diagenetic coatings have already significantly affected the trace metal/Ca ratios. The Mg/Ca ratios are similar to previously published values but display much larger variation than would be expected from the annual temperature change of less than 2 °C. An additional impact of the difference in the calcite saturation state between the Skagerrak and the Gullmar Fjord could explain the results. Mn/Ca ratios from G. turgida can potentially be related to variations in dissolved oxygen of the habitat where the foraminifera calcify. Samples from the Skagerrak display increased Mn/Ca in specimens that lived deeper in the sediment than those that lived near the surface. G. turgida samples from the low-oxygen Gullmar Fjord showed significantly increased Mn/Ca, being highest when bottom water dissolved oxygen was at a minimum. Our study suggests that trace metal/Ca ratios in benthic foraminifera from shelf regions have the potential to record past variations in bottom water temperature and dissolved oxygen concentrations, but an additional impact of the inorganic carbonate chemistry cannot be excluded.

Tolerance to low dissolved oxygen by the tubicolous polychaete Loimia medusa

1994 ◽  
Vol 74 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Roberto J. Llanso ◽  
Robert J. Diaz
Keyword(s):  
Dissolved Oxygen ◽  
Common Species ◽  
Severe Hypoxia ◽  
Sediment Surface ◽  
Low Oxygen ◽  
Low Dissolved Oxygen ◽  
Oxygen Concentrations

Tolerance and behaviour to hypoxia and anoxia by the annelid Loimia medusa (Savigny) (Polychaeta: Terebellidae), a common species in estuarine habitats where summer hypoxic events often occur, were examined in the laboratory. The worm can tolerate anoxia or severe hypoxia (7% air saturation at 26°C) for 3 to 5 d. Under low dissolved oxygen (<14% air saturation) feeding stops, although tube irrigation continues and periodic protrusions from the tube are common. Most worms come out to the sediment surface, but the number of worms dead on the surface is higher in anoxia than in hypoxia. The prevalence of L. medusa in deep estuarine channels may be partially explained by its tolerance to prolonged periods of hypoxia (14 d at 14% air saturation). Our data, however, suggest that subtle changes in oxygen concentrations may be important in the control of populations of L. medusa in habitats affected by low oxygen disturbances.

The proliferating Gastropoda Crepidula fornicata may stimulate macrozoobenthic diversity

1999 ◽  
Vol 79 (6) ◽  
pp. 1069-1077 ◽  
Author(s):  
X. de Montaudouin ◽  
P.G. Sauriau
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Western Europe ◽  
Benthic Communities ◽  
Coarse Sand ◽  
Community Diversity ◽  
Crepidula Fornicata ◽  
Deposit Feeders ◽  
Wide Range ◽  
Muddy Sediments

Since the late 19th century, the accidentally introduced Gastropoda Crepidula fornicata has been invading sheltered coastal waters of western Europe. The consequences of this proliferation on macrozoobenthic communities were studied in the Bay of Marennes-Oléron, France. Crepidula fornicata was found in a wide range of sediment grain sizes and depths, with however, a predilection for shallow muddy areas where abundance and biomass reached 4770 ind m−2 and 354 g DW m−2, respectively. Soft-sediment macrofaunal assemblages were compared in similar habitats, in the presence and absence of C. fornicata. In muddy and medium sand areas, abundance, biomass and species richness of macrofauna were generally greater in presence of C. fornicata, with Annelida dominating, although the differences were significant (P<0.05) only in one location out of five. The species composition was moderately different in the presence of C. fornicata. In coarse sand, the abundance of C. fornicata was low and did not affect abundance, biomass and species richness of the macrofauna. However, species composition differed where C. fornicata was absent, with a higher proportion of mobile Crustaceana. The effect of C. fornicata on benthic communities differs in relation to the habitat they colonize: in muddy sediments, the presence of C. fornicata apparently stimulates zoobenthic community diversity and abundance (mostly deposit-feeders), whereas in coarser sediments, macrofauna community is different (more suspension-feeders) from the community associated with C. fornicata.

scholarly journals Benthic foraminiferal response to variations in temperature, salinity, dissolved oxygen and organic carbon, in the Guanabara Bay, Rio de Janeiro, Brazil

2003 ◽  
Vol 26 ◽  
pp. 36-51
Author(s):  
Patrícia P. B. Eichler ◽  
Beatriz B. Eichler ◽  
Luiz B. de Miranda ◽  
Evelyn Da R. M. Pereira ◽  
Patrícia B. P. Kfouri ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Bottom Water ◽  
Distribution Patterns ◽  
Organic Carbon Content ◽  
Guanabara Bay ◽  
Low Oxygen ◽  
Water Conditions ◽  
Lower Temperature ◽  
Inner Parts

Recent benthic foraminiferal distribution patterns in Guanabara Bay are investigated in relation to temperature, salinity, dissolved oxygen and organic carbon content. Patterns of foraminiferal fauna differ between the entrance of the bay and inner parts. The primary result of the present study is that the distribution of Cassidulina subglobosa and Discorbis williamsoni appear to be governed by lower temperature and higher salinities being found in the entrance of the bay. According to dissolved oxygen content it was observed that Quinqueloculina seminulum occurs when values are higher than 2 mg/l, being intolerant to low oxygen bottom water conditions. By the other hand, Buliminella elegantissima, Bolivina striatula and Bulimmina elongata flourishes under low oxygen waters and in sediment where the organic matter accumulation is high, being found mainly in the central parts of the bay.

Spatio-temporal variability of zoobenthic communities in a tectonic lagoon (Lake Vouliagmeni, Attika, Greece)

2008 ◽  
Vol 88 (5) ◽  
pp. 873-881 ◽  
Author(s):  
Chariton Chintiroglou ◽  
Chryssanthi Antoniadou ◽  
Panagiotis Damianidis
Keyword(s):  
Multivariate Analyses ◽  
Benthic Communities ◽  
Marine Species ◽  
Trophic Group ◽  
Spatial And Temporal Scales ◽  
Mediterranean Lagoons ◽  
Deposit Feeders ◽  
Spatio Temporal ◽  
Lagoon Lake ◽  
Hard Substrata

Lake Vouliagmeni (Attica, Greece) is a lagoon of great scientific interest due to its endemic fauna, widely used for recreational activities. Understanding the dynamics of this peculiar ecosystem is essential for its conservation. An ecological survey of the benthic communities was carried out, in both spatial and temporal scales. Material was collected with SCUBA diving, by taking off samples from the principal habitats of the lagoon, i.e. meadows, soft and hard substrata. The identification of the collected 61,975 living specimens revealed the presence of 12 floral and 20 faunal species. Multivariate analyses separated the sampling sites according to the four different habitats of the lagoon, whereas no temporal patterns came up. Micrograzers were the dominant trophic group, followed by deposit feeders regardless of the habitat studied. Lake Vouliagmeni is among the less diverse Mediterranean lagoons, mostly due to its isolation from the sea that hinders the entrance of marine species.

Minimal Dissolved Oxygen Requirements of Aquatic Life with Emphasis on Canadian Species: a Review

1975 ◽  
Vol 32 (12) ◽  
pp. 2295-2332 ◽  
Author(s):  
John C. Davis
Keyword(s):  
Dissolved Oxygen ◽  
Water Body ◽  
Physical Factors ◽  
Seasonal Temperature ◽  
Low Oxygen ◽  
Aquatic Life ◽  
Invertebrate Species ◽  
Oxygen Regime ◽  
Response Thresholds ◽  
Oxygen Requirements

This article reviews the sensitivity, responses, response thresholds, and minimum oxygen requirements of marine and freshwater organisms with strong emphasis on Canadian species. The analysis attempts to define low dissolved oxygen thresholds which produce some physiological, behavioral, or other response in different species.Oxygen availability is discussed with reference to seasonal, geographical, or spatial variation in dissolved oxygen. Factors affecting availability of dissolved oxygen include atmospheric exchange, mixing of water masses, upwelling, respiration, photosynthesis, ice cover, and physical factors such as temperature and salinity. Dissolved oxygen terminology is summarized and tables are included for both fresh and saltwater O2 solubility at different temperatures.Incipient O2 response thresholds are used in a statistical analysis to develop oxygen criteria for safeguarding various groups of freshwater and marine fish. These include mixed freshwater fish populations including or excluding salmonids, freshwater salmonid populations, salmonid larvae or mature salmonid eggs, marine anadromous and nonanadromous species. Criteria are based on threshold oxygen levels which influence fish behavior, blood O2 saturation, metabolic rate, swimming ability, viability and normal development of eggs and larvae, growth, circulatory dynamics, ventilation, gaseous exchange, and sensitivity to toxic stresses. The criteria provide three levels of protection for each fish group and are expressed as percentage oxygen saturation for a range of seasonal temperature maxima.Oxygen tolerances and responses of aquatic invertebrates to low oxygen are reviewed for freshwater and marine species according to habitat. No invertebrate criteria are proposed owing to the capacity for many invertebrate species to adopt anaerobic metabolism during low O2 stress. It is suggested that the criteria proposed for fish species will provide a reasonable safeguard to most invertebrate species. It appears likely, however, that a change in oxygen regime to one of increased O2 scarcity will probably influence invertebrate community structure.It is suggested that criteria for protection of aquatic life be implemented by groups of experienced individuals. The group should consider the natural oxygen regime for a specific water body and its natural variability, the aquatic life therein and its value, importance, relative O2 sensitivity, and the possibility of interactions with toxicants and other factors that may compound the stress produced by low O2 on aquatic life. Each water body and its aquatic life should be considered as a unique situation and criteria application should not encompass diverse areas, habitats, or biological associations as if they were identical.

scholarly journals First record of Dero (Aulophorus) bimagnasetus Harman (Oligochaeta) from Brazil and habitat characteristics

2014 ◽  
Vol 74 (2) ◽  
pp. 483-488
Author(s):  
R. Campitelli-Ramos ◽  
JV. Lucca ◽  
LLD. Oliveira ◽  
MR. Marchese ◽  
O. Rocha
Keyword(s):  
Benthic Communities ◽  
First Record ◽  
Biological Data ◽  
Habitat Characteristics ◽  
Low Oxygen ◽  
Body Width ◽  
Ecological Information ◽  
Freshwater Biota ◽  
Physical And Chemical ◽  
First Time

Annelid worms represent a significant part of freshwater benthic communities worldwide and Oligochaeta is a particularly species-rich group. Dero (A) bimagnasetus (Naididae) previously found and described from a small marsh in Surinam in 1974, has now been found for the first time in Barra Lake, MG, Brazil. Due to the scarce biological data and absence of ecological information in the literature regarding this species we are presenting morphological information on the specimens obtained and the physical and chemical characteristics of the habitat they were found. This species occurred only in the littoral zone of Barra Lake, in muddy, low oxygen, low conductivity and low organic matter sediment. The four individuals collected ranged 3.17-4.15 mm total length; 0.25 - 0.26 mm body width and 0.16-0.21 mm3 total volume. Considering the present anthropic pressures on freshwater biota and fast biodiversity losses worldwide it is now recognized that attention must be paid to low abundance species and the urgency for preservation of their habitats.

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