Preliminary comparison of natural versus model-predicted recovery of vessel-generated seagrass injuries in Florida Keys National Marine Sanctuary

Each year, more than 500 motorized vessel groundings cause widespread damage to seagrasses in Florida Keys National Marine Sanctuary (FKNMS). Under Section 312 of the National Marine Sanctuaries Act (NMSA), any party responsible for the loss, injury, or destruction of any Sanctuary resource, including seagrass, is liable to the United States for response costs and resulting damages. As part of the damage assessment process, a cellular automata model is utilized to forecast seagrass recovery rates. Field validation of these forecasts was accomplished by comparing model-predicted percent recovery to that which was observed to be occurring naturally for 30 documented vessel grounding sites. Model recovery forecasts for both Thalassia testudinum and Syringodium filiforme exceeded natural recovery estimates for 93.1% and 89.5% of the sites, respectively. For Halodule wrightii, the number of over- and under-predictions by the model was similar. However, where under-estimation occurred, it was often severe, reflecting the well-known extraordinary growth potential of this opportunistic species. These preliminary findings indicate that the recovery model is consistently generous to Responsible Parties in that the model forecasts a much faster recovery than was observed to occur naturally, particularly for T. testudinum, the dominant seagrass species in the region and the species most often affected. Environmental setting (i.e., location, wave exposure) influences local seagrass landscape pattern and may also play a role in the recovery dynamics for a particular injury site. An examination of the relationship between selected environmental factors and injury recovery dynamics is currently underway. (PDF file contains 20 pages.)

The myogenic automatism of the systemic heart of Octopus vulgaris (Cephalopoda: Coleoidea): evidence for localized stretch sensitivity and pacing activity

The localization of the stretch sensitivity and myogenic automatism in the systemic heart of Octopus vulgaris has been studied on an isolated preparation in which the ventricle was zoned by ligatures. Each region has been submitted to two different levels of internal hydrostatic pressure (1 and 2 kPa). Only the two atrio-ventricular regions were able to contract regularly when submitted to internal pressure, with a frequency dependent from the pressure value, while the ventricle-aortic region was insensitive to the stretching by internal pressure. This result supports the hypothesis that the automatism in this heart is localized. Electrocardiogram recordings from different areas of an isolated and perfused preparation of the systemic heart ventricle are also reported, which suggest that the electrical activity of the ventricle originates in two narrow areas near the atrio-ventricular valves.

Determination of ubiquinone and tocopherol in heart, liver and muscle tissues of fresh water fish, Rohu (Labeo rohita, Hamilton)

The liver, heart and muscle tissues of Rohu, (Labeo rohita, Hamilton) were examined for their ubiquinone (UQ) and tocopherol contents. These three tissues contained respectively 11.60, 3.94 and 0.19 mg of ubiquinone and 10.16, 5.32 and 3.58 mg of tocopherol per 100 g. The 4% (V/V) of diethyl ether (EE) in light petroleum ether (PE) fractions of all three tissues on paper chromatographic separation gave spots having the same Rf value as standard ubiquinone-50 (UQ 10). Both the 4% and 6% (V/V) diethyl ether in light petroleum ether fraction of liver, heart and muscle tissues gave a single spot with the same Rf value as α – tocopherol.

Effect of electric stimulation on heart beat and body muscle in fish

The effect of AC and DC electric stimulations on the heart-rate and the entire body of Heteropneustis fossillis, Tilapia mossambica and Macrobrachium rosenbergii were studied and presented in kymograph tracings. The reaction of spinal cord in Puntius ticto, Heteropneustis fossilis and Tilapia mossambica to D. C. field was observed to find out its role in electric shocks. A test-check of the electrical resistance of a few species was also conducted. The effect of D. C. and A.C. on the body muscle was found to be the same as that in the case of frog. Different degrees of cardiac slowing were observed in AC and DC. Unbalanced galvanotropic movements were also noticed in spinal fishes.

The triglyceride fatty acids from heart lipids of Puntius sarana and their variation with different sizes

The triglyceride fatty acid components from the heart lipid of Puntius sarana of different sizes have been characterized by thin-layer and gas liquid chromatography. Csub(10) to Csub(24) acids including both odd-numbered and branched chain acids were detected. The major constituents were ante-iso Csub(10), Csub(10), Csub(12:2), Csub(14), Csub(16), Csub(16:1),Csub(17), Csub(18) , Csub(18:1), Csub(18:2), Csub(18:3) and Csub(20:4) while twenty other acids were detected in lower proportion. The composition of these acids and their variation with size of fish have been investigated and discussed.

Chronotropic and inotropic effects of adenosine and AMP on the isolated systemic heart of Octopus vulgaris

The effect of adenosine on the function of the heart in Octopus vulgaris was studied using an isolated heart preparation. Bolus injections of adenosine or AMP (adenosine precursor) induced both positive chronotropic and inotropic effects. The maximum inotropic effect preceded the maximum chronotropic effect. The impermeable adenosine analogue 2-chloroadenosine elicited a similar effect, while the adenosine uptake blocker dipyridamole did not affect the adenosine response. These results suggest that adenosine acted extracellularly. The concentration-response curves of adenosine and AMP were also determined, by evaluating the effects on ventricular and coronary function. Under these conditions, the potent chronotropic effect elicited by both substances apparently masked or compensated for the inotropic effect, owing to the negative force-frequency relationship known to occur in the octopus heart. The AMP displayed a lower threshold than adenosine, suggesting an higher affinity for the purinergic receptors involved or a strict association between 5'-nucleotidase and the adenosine receptor on the plasma membrane.

Development of cell culture from caudal fin and heart of Tor tor (Hamilton-Buchanan)

Tor mahseer (Tor tor), possess high commercial and recreational value as they are potential game as well as food fish of India. Two cell culture systems were developed from fin and heart of T. tor (Hamilton-Buchanan). The explants excised aseptically from fingerling of T. tor were cultured in Leibovitz-15 (L-15) medium with 20% fetal bovine serum (FBS). Radiation of cells started after 72 hours and 48 hours of explant attachment from caudal fin and heart respectively. Confluent monolayer of cells with heterogeneous morphology around fin explants was observed after 7-10 days, where as a homogenous confluent layer of fibroblastic cells from heart explant was observed after 12-13 days. The establishment of cell culture systems from different organs and tissues of commercial important species would facilitates in vitro research.