CRAB TRACES ON MUDDY TIDAL FLATS OF THE MIRA RIVER ESTUARY, PORTUGAL
Bibliographic record
Abstract
Abstract Intertidal burrowing crabs produce distinctive biogenic sedimentary structures on tidal flats and salt marshes of the mesotidal Mira River estuary in southwestern Portugal. This study shows that the morphology and spatial distribution of crab burrows vary depending on the activity of the producer, its age, tidal cycles, tidal range, time of the day, and substrate consistency. The Atlantic shore crab Carcinus maenas was observed during the daylight hours roaming the tidal flats and marshes at neap low tide (1.29 m) as well as occupying burrows and cavities. A variety of traces and tracks are attributed to C. maenas, including cheliped scratch marks, tracks and trackways, burrows/cavities with associated root penetration structures (rhizoliths), and fecal pellets. Scratch marks are understudied in neo- and paleoichnology and are often interpreted as structures resulting from crab grazing and feeding activity (fodichnia/pascichnia), and occasionally from mating behavior. Digit traces and trackways predominantly concentrate around burrows and cavities on the upper tidal flat and resemble Coenobichnus currani, representing crab locomotion (repichnia). With morphology regarded as the most important criteria for ichnotaxonomy, wide burrow apertures and cavities found on the tidal flats are most similar to Psilonichnus upsilon, P. tubiformis, and Spongeliomorpha-type crustacean burrows, representing permanent- to semi-permanent crab domichnia. Finally, cylindrical, semi-consolidated pellets are interpreted as crab fecal pellets (coprolites) similar to Favreina. Carcinus maenas is a prolific bioturbator in intertidal and supratidal habitats; however, the preservation of its traces in the rock record is dependent on the preservation potential of the host sediments.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".