Respiratory bronchoscopy of subadult American alligators (Alligator mississippiensis) and tracheal wash evaluation.

Twelve healthy approximately 3-yr-old captive-born 4.5-9 kg American alligators (Alligator mississipiensis) each had bronchoscopy and tracheal washes performed four times during a 10-mo period to evaluate seasonal respiratory microbiology and cytology. Cytologic evaluation of most samples showed a small amount of mucus and low numbers of ciliated columnar epithelium, cubodial epithelium, and keratinized squamous cells. No bacteria or parasites were observed, and there was no seasonal variation in the cytology. No significant bacterial or fungal growth was identified in any season. Hematology performed in the spring and fall evaluations showed seasonal variation in the red blood cell count, hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin concentration, eosinophil count, and thrombocyte count. The lower respiratory tract (at the tracheal level) of healthy subadult alligators appears to be sterile, and cytology is similar to that described in domestic mammals.     

Wound management in a juvenile tiger (Panthera tigris) with vacuum-assisted closure (V.A.C. Therapy).

A 6-wk-old tiger (Panthera tigris) was evaluated for severe skin lacerations from an adult tiger attack. A caudal superficial epigastric skin flap was surgically placed to cover a defect that could not be closed over the hind limb; however, the skin flap did not adhere well to the granulation tissue over a period of 1 mo. The granulation bed matured and deteriorated. A subatmospheric pressure technique (vacuum-assisted closure, V.A.C. Therapy, Kinetic Concepts Inc., San Antonio, Texas 78219, USA) was utilized, and flap adherence occurred after 4 wk. This technique should be considered when dealing with severe or chronic wounds in tractable animals.     

Latitudinally distinct stocks of Atlantic cod face fundamentally different biophysical challenges under on-going climate change

The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ considerably across the species' geographical distribution. Here we investigated the life history, focusing on reproductive ecology, of three spatially distant populations (stocks) of Atlantic cod (Gadus morhua, Gadidae) (50–80° N), in the Irish/Celtic Seas-English Channel Complex, North and Barents Seas, under past and projected climate. First, experimental tracking of spawning behaviour evidenced that the ovulation cycle is highly distressed at ≥9.6 (±0.25)°C (T_up). This knife-edge threshold resulted in erratic spawning frequencies, whereas vitellogenin sequestration remained unaffected, indicating endocrine rather than aerobic scope constraints. Cod in the Celtic Sea-English Channel are, therefore, expected to show critical stock depensation over the next decades as spawning grounds warm above T_up, with Irish Sea cod subsequently at risk. Second, in the relatively cooler North Sea, the northward retraction of Calanus finmarchicus (Calanidae) and Para-Pseudocalanus spp. (Clausocalanidae) (1958–2017) limit cod larvae feeding opportunities, particularly in the southernmost subarea. However, the contrasting increase in Calanus helgolandicus (Calanidae) does not counteract this negative effect, likely because cod larvae hatch ahead of its abundance peaks. Overfishing again comes as a twin effect. Third, in the still relatively cold Barents Sea, the sustainably harvested cod benefit from improved food conditions in the recent ice-free polar region but at the energetic cost of lengthier and faster spawning migrations. Consequently, under climate change local stocks are stressed by different mechanistic factors of varying management severity.     

Sensitivity of plants to acidic soils exemplified by the forest grass Bromus benekenii

The aim of this paper is to study the role of Al- and H-ions, base cation deficiency and N-nutrition as solely NH₄ in disturbing plant growth on acid soils. Effects of these factors on growth of the forest grass Bromus benekenii were studied experimentally and in the field and compared to other deciduous forest plants. Bromus benekenii is most frequent at pH >4.5 (soil solution) and absent at pH 3.8. In a pot experiment using an acid soil of pH 3.3, raised by steps to pH 5.2 by carbonate addition, growth of Bromus benekenii and nine other species (out of 17) was limited at pH <4.1. Toxicity of H-ions to Bromus benekenii was confirmed in a solution experiment at pH ≤4.2. Al-toxicity occurred at low Al-concentrations (20 μM) in Bromus benekenii and nine other tested species. Base cation (Ca+Mg) mitigation of Al-toxicity was found in a factorial solution experiment. Our experiments also indicate that H- and Al-ions interact in a way that makes combined treatments equally toxic as concentrations of H-or Al-ions alone. Incubation experiments showed that soil nitrification is retarded in acid soils. This may affect Bromus benekenii as it was most demanding on NO₃-availability out of 15 species in a solution experiment. Only 50% growth was attained in a NH₄- as compared to a NH₄+NO₃-treatment. Comparing experimental results with field data, we conclude that H- and Al-toxicity and unfavourable N-nutrition (as solely NH₄) to a similar extent may explain the acidifuge behaviour of field layer plants.