scholarly journals Prey fractionation in the Archaeocyatha and its implication for the ecology of the first animal reef systems

Paleobiology ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 652-675 ◽  
Author(s):  
Jonathan B. Antcliffe ◽  
William Jessop ◽  
Allison C. Daley
Keyword(s):  
Water Column ◽  
Geographic Distribution ◽  
Feeding Ecology ◽  
Food Resource ◽  
Outer Wall ◽  
Ecological Significance ◽  
Frequency Distributions ◽  
Upper Limits ◽  
Reef Communities ◽  
Modern Reef

AbstractArchaeocyaths are the most abundant sponges from the Cambrian period, having formed the first animal reef communities more than 500 million years ago. The Archaeocyatha are index fossils for correlating rocks of similar ages globally because of their abundance, extensive geographic distribution, detailed anatomy, and well-established taxonomy. Their ecological significance remains incompletely explored, yet they are known to have strongly competitively interacted, unlike modern sponges. This study examines the feeding ecology of the fossil remains of Siberian archaeocyath assemblages. As suspension feeders, archaeocyaths filtered plankton from the water column through pores in their outer wall. Here we outline a new method to estimate the limit on the upper size of plankton that could be consumed by an archaeocyath during life. The archaeocyaths examined were predominantly feeding on nanoplankton and microplankton such as phytoplankton and protozooplankton. Size-frequency distributions of pore sizes from six different Siberian archaeocyath assemblages, ranging from Tommotian to Botoman in age, reveal significantly different upper limits to the prey consumed at each locality. Some of the assemblages contain specimens that could have fed on larger organisms extending into the mesoplankton, including micro-invertebrates as a possible food resource. These results show that during the establishment of the first animal reef systems, prey partitioning was established as a way of reducing competition. This method has applicability for understanding the construction and the functioning of the first reef systems, as well as helping to understand modern reef systems and their development though time and space.

Population dynamics and feeding ecology of juvenile Australian salmon (Arripis trutta) in Westren Port, Victoria

1982 ◽  
Vol 33 (2) ◽  
pp. 369 ◽  
Author(s):  
AI Robertson
Keyword(s):  
Population Dynamics ◽  
Water Column ◽  
Feeding Ecology ◽  
Age Group ◽  
Gill Raker

Juveniles (0 + age group) of both subspecies of the Australian salmon were captured over eelgrass meadows in Western Port at various times between October 1974 and February 1976. The western subspecies and the eastern subspecies were present from August through April, and December through May, respectively. The western subspecies always fed on benthic-dwelling prey including fishes, crabs and shrimps, and the eastern subspecies fed on prey which inhabited the water column (crustacean larvae, insects and epitokous polychaetes) in December but switched to benthic-dwelling prey (fishes, small squid, benthic crustaceans and polychaetes) in May. The role of different gill-raker number and morphology in effecting dietary separation of the subspecies is unclear.

6. Reef fish and other major predators

2014 ◽  
Author(s):  
Charles Sheppard
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Reef Fish ◽  
Feeding Ecology ◽  
Natural Habitat ◽  
Marine Species ◽  
Reef Fishes ◽  
Symbiotic Relationships ◽  
The Earth ◽  
Reef Communities

Healthy reefs provide a habitat for an immense number of fish that come in a variety of shapes, sizes, and colours. No other natural habitat in the ocean shows this diversity and abundance. About a quarter of all marine species may be found on coral reefs even though this habitat occupies only one or two per cent of the area of the earth. ‘Reef fish and other major predators’ describes the diverse feeding ecology of reef fishes; coral reef predators such as the colourful crown of thorns starfish, Acanthaster plancii; symbiotic relationships between different species of fish or with different invertebrates; and the dangers of overfishing in reef communities.

Patterns of reef growth in the Middle Devonian Edgecliff Member of the Onondaga Formation of New York and Ontario, Canada, and their ecological significance

1992 ◽  
Vol 66 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Thomas H. Wolosz
Keyword(s):  
New York ◽  
Geographic Distribution ◽  
Water Depth ◽  
Middle Devonian ◽  
Composite Structures ◽  
Ecological Significance ◽  
Reef Growth

Reefs of the Middle Devonian Edgecliff Member of the Onondaga Formation in New York and Ontario, Canada, contain three distinct paleocommunities: the Phaceloid Colonial Rugosan Paleocommunity, the Favositid/Crinoidal Sandstone Paleocommunity, and the rare Delicate Branching Tabulate Paleocommunity. The reefs may be classified as mounds or composite structures based on the degree of intergrowth of the rugosan and favositid paleocommunities. Composite structures may be further subdivided into mound/bank, thicket/bank, and ridge/bank structures based on the degree of development of the rugosan paleocommunity. Geographic distribution of reef types suggests that these patterns of reef growth were controlled by water depth.

scholarly journals Zooplankton distribution in Mesophotic Corals at Bajo Frijol seamount, Colombian Caribbean

2021 ◽  
Vol 26 (3) ◽  
pp. 281-300
Author(s):  
Laura Contreras Vega ◽  
Alejandro Henao Castr ◽  
Gabriel R Navas S
Keyword(s):  
Water Column ◽  
Relative Abundance ◽  
Food Resource ◽  
Zooplankton Community ◽  
Mesh Size ◽  
Taxonomic Composition ◽  
Mesophotic Coral Ecosystems ◽  
Natural Park ◽  
Three Samples ◽  
Large Groups

Mesophotic coral ecosystems shelter unique communities, but have not been studied enough due to the high cost for the available technologies. The zooplankton have become the primary food resource of the polyps at these environments, due to the low photosynthesis rate of its zooxanthellae, . Therefore, the purpose of this work was to study the zooplankton community associated to the MCEs in Bajo Frijol, in the Corales de Profundidad National Natural Park, and compare its composition with the zooplankton community from shallower parts of the water column. Three samples were taken, filtering 24 L of seawater (45 µm mesh size) at each station with a device designed to collect zooplankton right on top of the reef substrate. The taxonomic composition, density and relative abundance were obtained. A resemblance analysis was performed, complemented with a cluster, an MDS and a modified Kandoorp test. The analysis showed clear differences between the water column samples from those taken close to the reef. It also showed the separation of the community at the seamount into two large groups: north and center-south, both with exclusive species.

scholarly journals Feeding ecology of the Green-cheeked Parakeet, Pyrrhura molinae (Psittaciformes, Psittacidae), in a subtropical forest of Argentina

2021 ◽  
Vol 16 (1) ◽  
pp. 205-219
Author(s):  
Analía Benavídez ◽  
Ever Tallei ◽  
Echevarría Ada Lilian ◽  
Luis Rivera
Keyword(s):  
Plant Species ◽  
Feeding Ecology ◽  
Resource Availability ◽  
Food Resource ◽  
Fruit Production ◽  
Fleshy Fruit ◽  
Wet Season ◽  
Food Items ◽  
Trema Micrantha ◽  
High Flexibility

Although there are studies on certain aspects of the feeding ecology of several species of Neotropical parrots, there is scarce ecological information about Pyrrhura molinae – a Psittacidae species which is widely distributed in South America and abundant in the Yungas of Argentina. For two years (May 2014 to June 2016), the composition and seasonal variation in the Green-cheeked Parakeet diet in the Yungas Piedmont forest in Jujuy, Argentina were examined. Furthermore, fruiting phenology transects were established to evaluate food resource availability and the patterns of food resource used by the Green-cheeked Parakeet. In 214 food plant trees, it was found that flower and dry fruit availability was highest in the dry season, and fleshy fruit production peaked in the wet season, but these phenology patterns for aged plant species suggest that there were no significant differences in food availability. The consumption of 18 plant species was recorded, being Celtis iguanaea (30.73%) and Trema micrantha (22.01%) the most consumed species. In terms of food items, fruits were the most consumed items, followed by seeds and flowers and, to a lesser extent, nectar and leaves. Levins’ niche breadth showed varying levels of diet specialisation amongst seasons, which was narrower (B = 0.28) in the wet season, indicating specialisation in diet during this season. There was a medium overlap in parakeet diet between seasons (Morisita Index = 0.59). We did not find a statistically significant relationship between resource availability and food use, but expansion and contraction in Levins Index and variation in food items consumed throughout the year and season demonstrate high flexibility in the diet. Like other congeners, the Green-cheeked Parakeet has a flexible diet that could be adjusted to the seasonal availability of food resources. These data may contribute to the design of conservation plans for the species and its habitat.

scholarly journals Missing water in Class I protostellar disks

2020 ◽  
Vol 636 ◽  
pp. A26 ◽  
Author(s):  
D. Harsono ◽  
M. V. Persson ◽  
A. Ramos ◽  
N. M. Murillo ◽  
L. T. Maud ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Column ◽  
Planet Formation ◽  
Physical Structure ◽  
Class I ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Water Abundance ◽  
Spatially Resolved ◽  
Upper Limits

Context. Water is a key volatile that provides insight into the initial stages of planet formation. The low water abundances inferred from water observations toward low-mass protostellar objects may point to a rapid locking of water as ice by large dust grains during star and planet formation. However, little is known about the water vapor abundance in newly formed planet-forming disks. Aims. We aim to determine the water abundance in embedded Keplerian disks through spatially-resolved observations of H218O lines to understand the evolution of water during star and planet formation. Methods. We present H218O line observations with ALMA and NOEMA millimeter interferometers toward five young stellar objects. NOEMA observed the 31,3–22,0 line (Eup∕kB = 203.7 K) while ALMA targeted the 41,4–32,1 line (Eup∕kB = 322.0 K). Water column densities were derived considering optically thin and thermalized emission. Our observations were sensitive to the emission from the known Keplerian disks around three out of the five Class I objects in the sample. Results. No H218O emission is detected toward any of our five Class I disks. We report upper limits to the integrated line intensities. The inferred water column densities in Class I disks are NH218O < 1015 cm−2 on 100 au scales, which include both the disk and envelope. The upper limits imply a disk-averaged water abundance of ≲10−6 with respect to H2 for Class I objects. After taking the physical structure of the disk into account, the upper limit to the water abundance averaged over the inner warm disk with T > 100 K is between ~10−7 and 10−5. Conclusions. Water vapor is not abundant in warm protostellar envelopes around Class I protostars. Upper limits to the water vapor column densities in Class I disks are at least two orders of magnitude lower than values found in Class 0 disk-like structures.

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