Methods for the Study of Marine Benthos

A glossary and some basic taxonomy on all of the species used in this book have been provided, as an appendix, for those readers who want to go a step further. The bibliography is also in the appendix and includes all the text references as well as those only in the taxonomy section of the appendix; this should provide a good literature base for further study. A variety of applications have been shown here, such as: Climatic (including sea-level) Pollution impact, monitoring, mitigation Seismic activity “fingerprints” Sediment transport phenomena (tracers) Storm activity tracers Paleoproductivity indicators Classification and characterisation of estuaries Freshwater–marine transitions There are also remarks on several other subjects. Biostratigraphy, which is the most widely known of all microfossil applications, has been excluded as it was felt that it has been already documented in great detail elsewhere; the type of applications discussed in this book represent the future of micropaleontology and will likely be the most often used in the coming decades. It is clear that there are almost as many applications for microfossils as there are environmental problems. The authors have discussed a few examples derived from their own experience, but new types of problems arise almost daily. The readers of this book should consider these examples as just that – examples – whereas the techniques discussed in the book can be applied to any type of problem that may be encountered in aquatic environments.

Monitoring in Coastal Environments Using Foraminifera and Thecamoebian Indicators: Conclusions and Final Remarks

Biodiversity metrics are critical for assessment and monitoring of ecosystems threatened by anthropogenic stressors. Existing sorting and identification methods are too expensive and labour-intensive to be scaled up to meet management needs. Alternately, a high-throughput DNA sequencing approach could be used to determine biodiversity metrics from bulk environmental samples collected as part of a large-scale biomonitoring program. Here we show that both morphological and DNA sequence-based analyses are suitable for recovery of individual taxonomic richness, estimation of proportional abundance, and calculation of biodiversity metrics using a set of 24 benthic samples collected in the Peace-Athabasca Delta region of Canada. The high-throughput sequencing approach was able to recover all metrics with a higher degree of taxonomic resolution than morphological analysis. The reduced cost and increased capacity of DNA sequence-based approaches will finally allow environmental monitoring programs to operate at the geographical and temporal scale required by industrial and regulatory end-users.

/pdf/large-scale-biomonitoring-of-remote-and-threatened-1q2udcpwnc.pdf

Large-Scale Biomonitoring of Remote and Threatened Ecosystems via High-Throughput Sequencing

Burial of biogenic silica (bSitotal) in high sedimentation rate continental margins remains highly uncertain. Cosmogenic 32Si (t1/2~140 years) can be used to trace the fates of bSitotal postdeposition, including as opal (bSiopal) and diagenetically altered opal (bSialtered), the latter dominantly authigenic clay (bSiclay). To determine the magnitude and form of bSitotal storage in coastal sediments, conventional operational leaches targeting bSiopal and bSialtered (including bSiclay) were modified for large-scale samples necessary for measurement of 32Si. The 32Si activity was used to estimate total biogenic silica burial (bSitotal = bSiopal + bSialtered) in several depositional settings: Gulf of Papua, Gulf of Mexico, Long Island Sound, and in the previously studied Amazon-Guianas deltaic system. In subtropical and temperate regions, 32Si was detected in both traditional biogenic silica leaches (bSiopal) and residual authigenic clays. Traditional bSiopal and modified operational leaches designed to target the most reactive authigenic silicates (~bSialtered) consistently underestimate authigenic clay formation (bSiclay) and thus the magnitude of bSitotal burial in temperate coastal zones and subtropical deltas by 2–4-fold. In tropical deltas, 32Si activities in the residual fraction after removal of bSiopal demonstrate rapid and almost complete alteration of initial bSiopal to new forms, most likely bSiclay. Globally, 4.5–4.9 Tmol/yr Si may be trapped in marine nearshore deposits as rapidly formed clay (bSiclay), 100% of the “missing silica sink” in the marine silica budget.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GB005746

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic 32Si

Assessment of the ecological quality (EcoQ) of the Venice lagoon using the structure and biodiversity of the meiofaunal assemblages

The effects of the human impact on the coastal environments and relative biota can be different and even greater than those derived by natural fluctuations. The major disturbance causes in the coastal systems are rivers that may be important sources of nutrients and pollutants, particularly in a semi-closed basin such as the Adriatic Sea. In this context, we investigated the distribution of both meiobenthic and nematode assemblages in the Central Adriatic Sea to evaluate whether and how they are influenced by riverine discharges and which faunal descriptors are the most effective in detecting this type of stress. On the basis of our results, the disturbance effects in the studied area might be caused by both local streams and Po plume, and even if the latter might be considered of lesser extent, it is worthy to note its real impact at a short distance from the coastline. Meiobenthic assemblage structure appears as a good tool for detecting short-term responses of the benthic domain, whereas nematode assemblages seem more useful for defining long-term responses. Accordingly, the former highlighted from poor to sufficient ecological quality status (EQS) of this area, whereas the latter from moderate to bad EQS. Life strategy traits prove to be the most informative faunal descriptor due to their high correspondence with the environmental variables and particularly with this type of disturbance.

/pdf/meiobenthos-and-free-living-nematodes-as-tools-for-7e9fb30m5c.pdf

Meiobenthos and free-living nematodes as tools for biomonitoring environments affected by riverine impact

Multidisciplinary study to monitor consequences of pollution on intertidal benthic ecosystems (Hauts de France, English Channel, France): Comparison with natural areas

Benthic foraminifera in transitional environments in the English Channel and the southern North Sea: A proxy for regional-scale environmental and paleo-environmental characterisations.

The mineralogical composition of 95 surface sediment samples from the Cariaco Basin continental shelf and Orinoco delta was investigated in order to constrain the clay-mineral main provenance and distribution within the Cariaco Basin. The spatial variability of the data set was studied using a geo-statistical approach that allows drawing representative clay-mineral distribution maps. These maps are used to identify present-day dominant sources for each clay-mineral species in agreement with the geological characteristics of the main river watersheds emptying into the basin. This approach allows (1) identifying the most distinctive clay-mineral species/ratios that determine particle provenance, (2) evaluating the respective contribution of local rivers, and (3) confirming the minimal present-day influence of the Orinoco plume on the Cariaco Basin sedimentation. The Tuy, Unare, and Neveri Rivers are the main sources of clay particles to the Cariaco Basin sedimentation. At present, the Tuy River is the main contributor of illite to the western part of the southern Cariaco Basin continental shelf. The Unare River plume, carrying smectite and kaolinite, has a wide westward propagation, whereas the Neveri River contribution is less extended, providing kaolinite and illite toward the eastern Cariaco Basin. The Manzanares, Araya, Tortuga, and Margarita areas are secondary sources of local influence. These insights shed light on the origin of present-day terrigenous sediments of the Cariaco Basin and help to propose alternative explanations for the temporal variability of clay mineralogy observed in previously published studies

/pdf/clay-mineralogy-of-surface-sediments-as-a-tool-for-5qgg2aqfeo.pdf

E. Armynot du Châtelet

Papers

Meiobenthos and free-living nematodes as tools for biomonitoring environments affected by riverine impact

Multidisciplinary study to monitor consequences of pollution on intertidal benthic ecosystems (Hauts de France, English Channel, France): Comparison with natural areas

Benthic foraminifera in transitional environments in the English Channel and the southern North Sea: A proxy for regional-scale environmental and paleo-environmental characterisations.

Clay mineralogy of surface sediments as a tool for deciphering river contributions to the Cariaco Basin (Venezuela)