Laminated diatomaceous sediments from Effingham Inlet, British Columbia, are described and classified in this study. Analyses were made from ten 15-cm long sediment slabs, spanning the last 5500 years, and 52 thin sections from which 408 sedimentary couplets were identified. Microfossil analysis and radiocarbon dating of the sediments reveal that the laminae are annually deposited (i.e., varves), with couplets containing a terrigenous and diatomaceous lamina pair. Terrigenous laminae, averaging 0.56 mm in thickness, consist of silt, organic debris, and robust diatoms, and are deposited during the winter months. Diatomaceous laminae, with a mean thickness of 1.85 mm, can be divided into three component laminae of differing compositions that reflect changing seasonal conditions during the spring, summer, and autumn months. This seasonal succession is seen in 76% of the couplets examined, recurring year after year with variations in couplet thickness and species occurrence. Couplets lacking the succession may represent deposition during periods of low diatom production or years with low seasonality (e.g., El Niño). Variability in couplet styles corroborates climate trends derived from pollen and Neoglacial studies. Sediments older than 4000 yr BP (calibrated radiocarbon dates) contain couplets with a distinct annual succession, and are interpreted to have been deposited during conditions that were warmer than today. Sediments deposited between 2000 to 4000 yr BP also contain couplets with an annual succession, but the laminated intervals are interrupted by brief nonlaminated intervals. The sediments were likely deposited during cooler and wetter conditions than today. Sediments younger than 2000 yr BP were deposited during modern conditions. This study illustrates the effective utility of an ultra high-resolution analysis of laminated sediment records, once proxy indicators are defined, and is important for understanding post-glacial climate evolution along the coast of British Columbia and throughout the northeast Pacific Ocean during the late Holocene.

In a companion study to earlier work in the Indo-Pacific, taphonomic alteration in reef-coral death assemblages was assessed in four distinct reef habitats ranging from 2–30 m water depth in the Florida Keys reef tract. Physical and biological taphonomic attributes measured from coral specimens showed great variability with respect to reef environment. Physico-chemical degradation (abrasion and dissolution) was greatest in reef-crest and patch-reef environments. With the exception of encrusting foraminifera, coverage by epi- and endobionts was higher in deep-reef environments (20 m and 30 m). Variability in dissolution and abrasion is likely the result of the different energy regimes present in the reef habitats examined. Variability in biological attributes results from a combination of increased residence time of coral skeletons on substrates in deep-reef environments, higher overall coral skeletal densities of corals inhabiting deep reef environments, and increased nutrient availability in the deep reefs sampled. Clear gradients in the degree of taphonomic alteration of reef corals with reef habitat indicate the utility of corals as taphofacies indicators in ancient reef settings. In contrast to shallow-water reefs on the Great Barrier Reef, taphonomic alteration of corals in the Florida Keys was equitable across growth forms.

Certain members of the bryozoan genus Celleporaria form large, erect colonies of hollow branches (∼10–30 cm tall and 1–3 cm diameter). These are common and conspicuous in Pleistocene and Cenozoic neritic strata of the southern margin of Australia. Most of these basins are characterized by decimeter-scale cycles through subtidal, heterozoan, cool-water, carbonate sediments. Several intervals are further characterized by pervasive celleporarid bryozoan thickets (10–30 cm thick), individual units of which can be traced for many tens of kilometers.

Study of modern, live celleporarid bryozoans from the continental shelf of the Great Australian Bight (GAB), Pleistocene celleporarid mounds stranded below the shelf break of the Australian margin, and Miocene celleporarid thickets from the Murray and Torquay Basins indicates that Celleporaria thickets form under specific environmental conditions: i.e., low-energy or sub-swell wave-base settings, mud-silt substrate, medium-high mesotrophy, and moderate sedimentation rate. These conditions, however, are not site specific. They are manifested here in two different environmental settings: (1) a deep-water (>200 m), upwelling nutrient source, below the shelf break during extreme sea-level low stands; and (2) shallow-water (<50 m), terrestrial nutrient source, in embayments, far inland from the shelf break during relative high stands of sea-level.

The celleporarid growth habit (species specific—not an ecomorph) allows their populations to proliferate in spatially restricted, transitional, geologically short-lived environments where most other bryozoans cannot cope. Their environmental sensitivity means that Celleporaria have great potential for paleoenvironmental analysis of Cenozoic carbonate Tethyan sediments.

During the Middle to Late Oxfordian (locally ranging into the earliest Kimmeridgian), the epicontinental shelf that persisted in the southeastern paleomargin of Iberia (Prebetic Zone) was largely colonized by siliceous sponges (Dictyida, Lychniskida, and Lithistida, in descending order of abundance). Spongiolithic lithofacies (sponge-rich deposits in which buildups are rare and small) represent a marine environment extensively colonized by sponges in the form of large sponge meadows showing associated epibenthic organisms (brachiopods, bivalves, and echinoderms). Marl-limestone rhythmites represent muddy bottoms colonized by scarce endobenthos (bivalves and irregular echinoids). However, the occurrence of patchy sponge bioherms provided a favorable substrate for epibionts and microbial lithoherms (microbialites). The record of meter-scale buildups showing sponge bioherm-microbial lithoherm in marl-limestone rhythmites resulted from the preferred colonization of sponge patches by benthic microbial communities, the growth of which on surrounding muddy bottoms was very limited or impossible. Sedimentation rate, substrate, bathymetry, light, nutrients, oxygenation, and environmental (water) energy determined the eco-sedimentary conditions responsible for the occurrence and composition of spongiolithic facies in the area studied. Throughout the Late Oxfordian and the earliest Kimmeridgian, the progressive increase in the rate of sedimentation, especially influx of siliciclastics, forced the disappearance of sponge bioherms-microbial lithoherms from the Prebetic shelf.

The stems of once-living Ordovician crinoids, especially the genera Ectenocrinus, Iocrinus, and Cincinnaticrinus, provided suitable attachment sites for the growth and development of both individuals and clusters of Cornulites—a tubiculous, suspension-feeding, worm-like organism. This association of cornulitids as opportunistic secondary tierers on crinoids was common from the Late Edenian into the Maysvillian in the Kope and Fairview portions of the Cincinnatian Series in the Cincinnati Arch area and less common in the Richmondian. Cornulitids utilizing this elevated location avoided some of the turbidity problems associated with an unstable, muddy substrate, and benefited from their ability to feed at a higher tier level. Several specimens of the byssate clam Ambonychia document the presence of Cornulites as secondary, low-level tierers on these bivalves, mainly during the Richmondian. Cornulitids positioned themselves on these ambonychiids to take advantage of feeding currents generated by the host. Cornulitids were also epizoans on the epifaunal clam Caritodens.

Using a field analysis of Upper Ordovician mollusc-rich faunas of the Cincinnati Arch, this study tests whether the large-scale patterns of Ordovician gastropods and bivalves observed in a companion study are maintained at the finer scales of individual strata and localities, and when utilizing abundance data in addition to taxonomic richness. Non-metric multidimensional scaling and several statistical analyses show that the taxonomic richness and abundance of these classes within samples were significantly negatively correlated, such that bivalve-rich settings were only sparsely inhabited by gastropods and vice versa. There also were important environmental differences between these classes. Gastropods were most dominant in shallow, carbonate-rich, and generally low-turbidity settings. Gastropods also occurred in restricted lagoons, where bivalves were only minor elements. In contrast, bivalves were most dominant in deep subtidal, siliciclastic shales with high levels of turbidity. Both in terms of abundance and taxonomic richness, these results strongly support those observed at the larger scales of paleocontinents and the globe. Taken together, these results argue that, despite similar taxonomical diversification patterns of these classes at the global scale and heterogeneous patterns among paleocontinents and among regions within Laurentia, gastropods and bivalves had quite different, yet unchanging, environmental distributions throughout the Ordovician, and that these classes did not co-occur to a significant degree, either in terms of taxonomic richness or abundance.

Tiering and ichnoguild analysis provide valuable evidence on marine benthic paleoecology. This paper provides the first detailed study on the ecology of a Cambrian deep-marine ichnofauna by means of the analysis of its ichnoguilds and tiering structure. Endobenthic tiering in this Early Cambrian deep-sea community was moderately developed. Biogenic structures were emplaced mostly in the uppermost millimeters of the substrate, with the exception of post-depositional burrows preserved on the base of turbidite sandstones. Four ichnoguilds are defined. The Palaeophycus ichnoguild includes semi-permanent, shallow-tier, suspension feeder structures produced by vagile vermiform organisms. The Oldhamia ichnoguild consists of semi-permanent, very shallow-tier, undermat-miner structures produced by stationary vermiform organisms. The Helminthopsis ichnoguild comprises transitory, near-surface to very shallow-tier, mat-grazer structures produced by vagile vermiform animals. The Diplichnites ichnoguild consists of transitory, surface structures produced by vagile arthropods. Comparisons with coeval ichnofaunas indicate that these ichnoguilds are widespread in Vendian–Cambrian deep-marine biotas. This analysis suggests that Cambrian deep-water communities were remarkably different from younger examples and stresses the importance of microbial mats on the ecology of Neoproterozoic–Cambrian ecosystems. Feeding strategies associated with microbial mats persisted in the deep sea after the agronomic revolution that took place in shallow-water environments, suggesting a gradual closure of a taphonomic window during the Proterozoic–Cambrian transition. The presence of post-depositional burrows of the Palaeophycus ichnoguild at the base of turbidite sandstones indicates a higher burrowing depth than those envisaged by current models.