Salt marshes, which represent the final stage in the leveling of marine delta plains or the filling of depressions, embayments, and other irregularities along coasts, are to some extent a measure of coastal stability or equilibrium. The overall sedimentary sequence is therefore a potential record of coastal history; it may reveal complete successions from original estuary, delta, lagoon, or bay floors to the highest intertidal flat, including lateral variations in contemporaneous facies or subfacies. Associated mineral suites are equally important indicators of both sources and possible recycling of coastal sediments. As habitable dwelling space for numerous organisms, some of which are uniquely adapted to stressful conditions, salt marsh substrates record many details of significance in paleoecology, ichnology, and environmental reconstruction.

Coastal Salt Marshes

Suspended sediments in the turbidity maximum of Chesapeake Bay include composite particles which contain platy mineral grains, arranged both in pellets (attributable to fecal pelletization) and in networks of angular configuration (attributable to electrochemical flocculation and coagulation).

Microstructure of Agglomerated Suspended Sediments in Northern Chesapeake Bay Estuary

The classic food pyramids in the sea consist of a plant-microbial base nurtured by sunlight or organic debris, which is consumed by invertebrates, which in turn are eaten by carnivores. This food pyramid can be based on neustonic ecosystems at the sea-air interface, on planktonic ecosystems living free in the water, on epibiotic ecosystems attached to surfaces, or on benthic ecosystems within the sea floor. As a result of the feeding processes in and on each of these ecosystems, a very large amount of excrement is released into the environment. As organisms are eaten and transformed from ingesta to feces or pseudofeces to sedimenting debris, or die to follow a similar fate, they form a fifth and often overlooked or misunderstood series of fecal-sestonic ecosystems. If it were not for the bacteria which solubilize particulate organic matter and utilize soluble organic matter, and the bacteria-eating protozoa and larger forms that feed upon them, the "waste products" resulting from excretion, defecation, and death could be considered a loss to the food pyramid (234). But bacteria and bacteria-eating forms are present in considerable numbers throughout the lengths and depths of the seas and occur as indispensable components in all five ecosystems. The bacterial-protozoan partnership that utilizes dissolved organic carbon (DOC) and particulate organic carbon (POC) is not separate from "the mainstream of tropho-dynamics" as believed by Strickland (234), but is a mechanism for keeping DOC and POC in the mainstream of tropho-dynamics by connecting the ecosystems and maintaining the long-term steady state of life in the sea. A detailed reevaluation of the nature of suspended and sedimenting organic debris, also known as POC or seston, is needed because currently accepted notions may be incorrect and preventing the development of more accurate working hypotheses. Evaluations of the nature of POC in seawater (72, 185) assume that most of this material is produced from DOC that comes out of solution to form "organic

https://www.jstor.org/stable/info/2096868

Bacterial substrates and productivity in marine ecosystems

The fauna of the HEBBLE site: patterns in standing stock and sediment-dynamic effects

Coprolites (fossilized faeces) are common, yet previously unreported, elements in the Campanian (Upper Cretaceous) shallow-marine strata of Asen, southern Sweden. They are associated with a diverse vertebrate fauna and comprise at least seven different morphotypes that suggest a variety of source animals. Their faecal origin is corroborated by several lines of evidence, including chemical composition (primarily calcium phosphate), external morphology and nature of the inclusions. Preservation in a fossil coquina, interpreted as a taphocoenosis, suggests early lithification promoted by rapid entombment. This would have prevented disintegration of the faecal matter and facilitated transportation and introduction to the host sediment. The coprofabrics can generally be correlated to specific gross morphologies, supporting a morphology-determined coprolite classification. Moreover, having been deposited under presumably comparable taphonomic conditions, variations in coprofabrics infer differences in diet and/or digestive efficiency of the host animal. Size and morphology of the coprolites imply that most, if not all, were produced by vertebrates and the largest specimens infer a host animal of considerable size. Two spiralled coprolite morphotypes yield bone fragments and scales of bony fish, suggesting that the producers were piscivorous sharks. Other coprolites contain inclusions interpreted as the remains of shelled invertebrates, thus indicating that they may have derived from durophagous predators and/or scavengers. The occurrence of small scrapes, tracks and traces on several specimens suggest manipulation of the faeces by other (presumably coprophagous) organisms after deposition. The collective data from the Asen coprolites provide new insights into a shallow-water Late Cretaceous marine ecosystem hitherto known solely from body fossils. (Less)

Coprolite morphotypes from the Upper Cretaceous of Sweden: novel views on an ancient ecosystem and implications for coprolite taphonomy

Fecal pellets voided by 70 invertebrate species are described, 66 of these for the first time. Pellet size is related to size of animals, and linear regressions are given for two species. Pellet characteristics described are cross-sectional shape, sculpture, differentiation, composition, and shape. The morphology is specific for many animals. However, certain species void feces which are 1) diffuse, 2) morphologically inconsistent, or 3) lack differentiating characteristics.

https://www.jstor.org/stable/pdfplus/1351239.pdf

Dexter S. Haven

Papers

Fecal pellets of common invertebrates of lower York River and lower Chesapeake Bay, Virginia