Increased salinity affects survival and osmotic response of rusty crayfish Orconectes rusticus Girard, 1852 and northern clearwater crayfish O. propinquus Girard, 1852 (Decapoda: Astacoidea: Cambaridae) as salinity increases: the potential for estuarine invasions
Bibliographic record
Abstract
The potential colonization of the rusty crayfish, Orconectes rusticus (Girard, 1852), has previously focused on lakes and streams of northeastern United States and southeastern Canada, but estuaries have not been considered. Rusty crayfish have recently been reported in tributaries of the Chesapeake Bay and the potential exists for crayfishes to invade and spread into the estuary. We determined survival, hemolymph osmotic pressure, and identified possible mechanisms of osmoregulation of the invasive O. rusticus and northern clearwater crayfish, Orconectes propinquus (Girard, 1852), in salinities of 0.5, 5, 15, and |$30\;{\rm{ppt}}$|. Survival of both crayfishes |$( \gt 83\% )$| was unaffected at salinities of up to |$15\;{\rm{ppt}}$| but declined significantly at |$30\;{\rm{ppt}}$| to |$17\% $| for O. rusticus|$(P \lt 0.05)$| and |$50\% $| for O. propinquus|$(P \gt 0.05)$|. Hemolymph osmotic pressure in both species was higher than the external medium up to |$15\;{\rm{ppt}}$|, and then became nearly isosmotic with salinities at |$30\;{\rm{ppt}}$| with a significant species by treatment interaction |$({F_{3,55}} = 4.4627,\;P = 0.0071)$|. The primary osmoregulatory mechanisms in crayfishes involve ions (|${\rm{N}}{{\rm{a}}^ + }$| and |${\rm{C}}{{\rm{l}}^ - }$|) and free amino acids (FAAs) in muscle tissues. Concentrations of |${\rm{N}}{{\rm{a}}^ + }$| and |${\rm{C}}{{\rm{l}}^ - }$| increased with increasing salinity in both species and accounted for |$74-91\% $| of the total hemolymph osmotic pressure with a significant species (Pillai’s |${\rm{Trace}} = 0.9565,\;P \lt 0.0001$|) and treatment effect (Pillai’s |${\rm{Trace}} = 0.23189,\;P \lt 0.0001$|). FAA concentrations in hemolymph remained low |$(1-4\;{\rm{mM}})$| and did not differ significantly with increased salinity |$(P \gt 0.05)$|. FAA in tail muscle tissue increased significantly with increasing salinity with a significant species by treatment interaction |$({F_{3,20}} = 5.1911,\;P = 0.0082)$|. Both O. rusticus and O. propinquus were active in salinities of up to |$15\;{\rm{ppt}}$| and were able to osmoregulate. Based on these laboratory experiments, the potential exists for both of these species to spread through large areas of estuaries into new rivers potentially threatening previously isolated watersheds.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".