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ideae#c --001a1141babadbc77b05673aa504 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Having raised many waterfowl chicks at CWRC last summer, we always include duckweed in their diet and we had to look HARD for it last year..whereas other years it was everywhere. Helene Helene Van Doninck DVM Cobequid Wildlife Rehabilitation Centre 2220 Irwin Lake Rd Brookfield NS Canada B0N1C0 902-893-0253 helene.birdvet@gmail.com <birdvet@hotmail.com> www.cwrc.net Find us on Facebook <https://www.facebook.com/pages/Cobequid-Wildlife-Rehabilitation-Centre/134= 671693239334> and Twitter <https://twitter.com/CobequiWildlife> ****Wildlife Matters**** On Sat, Mar 10, 2018 at 5:42 PM, N Robinson <nrobbyn@gmail.com> wrote: > Interesting discussion - thank you! > > And then there is Wikipedia re interesting research going on: > https://en.wikipedia.org/wiki/Lemnoideae > > "Duckweed is being studied by researchers around the world as a possible > source of clean energy. In the United States, in addition to being the > subject of study by the DOE, both Rutgers University > <https://en.wikipedia.org/wiki/Rutgers_University> and North Carolina > State University > <https://en.wikipedia.org/wiki/North_Carolina_State_University> have > ongoing projects to determine whether duckweed might be a source of > cost-effective, clean, renewable energy > <https://en.wikipedia.org/wiki/Renewable_energy>.[18] > <https://en.wikipedia.org/wiki/Lemnoideae#cite_note-18>[19] > <https://en.wikipedia.org/wiki/Lemnoideae#cite_note-19> Duckweed is a > good candidate as a biofuel because it grows rapidly, produces five to si= x > times as much starch as corn per unit of area, and does not contribute to > global warming.[20] > <https://en.wikipedia.org/wiki/Lemnoideae#cite_note-20>[21] > <https://en.wikipedia.org/wiki/Lemnoideae#cite_note-21> Unlike fossil > fuels, duckweed removes carbon dioxide from the atmosphere instead of > adding it.[22]" <https://en.wikipedia.org/wiki/Lemnoideae#cite_note-22> > > Nancy > > > On Sat, Mar 10, 2018 at 3:52 PM, David <dwebster@glinx.com> wrote: > >> Hi Steven & All, >> Good points. Aquatic plants typically have specialized tissues of >> interconnected passages which are filled with gas when the plant is acti= ve >> and I would expect this to be true of Lemna also. The relative solubilit= y >> of CO2 and O2 in water is no doubt relevant; CO2 is 16.4 and 31.5 times = as >> soluble in water as O2 at 0o C and 10oC respectively. So during the grow= ing >> season, photosynthesis would keep such aerenchyma filled with O2. With >> shorter days and less photosynthesis, CO2 production by respiration (ye= ar >> round in all living tissue night and day) would gradually exceed O2 >> production and lead to a flooding of the ballast tanks as the CO2 >> dissolves; submarine down. >> No doubt details of the anatomy play a part but I would expect >> stomata if present to be on the upper surface. >> Yt, DW,Kentville >> >> >> ------ Original Message ------ >> From: "Stephen Shaw" <srshaw@Dal.Ca> >> To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca> >> Sent: 3/10/2018 3:20:47 PM >> Subject: Re: [NatureNS] Duckweed >> >> Interesting puzzle, perhaps not so simple. Any cell system like a live >> leaf is bound to be somewhat denser than pond water, regardless of dense= r >> starch, so will naturally sink at all times unless kept buoyant by the >> extracellular gas bubbles or some other modification. What seems to nee= d >> explaining is why the bubbles are maintained in summer (dissolved gases = can >> pass through lipid cell membranes quickly, so you=E2=80=99d expect them = to dissolve >> out into the surrounding pond), and why they disappear in winter. He >> doesn=E2=80=99t seem to know if it=E2=80=99s CO2 or O2 in the bubbles, o= r both. Perhaps >> they are largely O2 in summer and dissolve and normally pass out of the >> leaf to oxygenate the pond and dissolved CO2 moves in, but leaf >> photosynthesis is sufficiently high in summer to maintain them, despite >> these losses. In winter gas production simply stops, and the non-buoyan= t >> plants sink. As winter ends, respiration produces bubbles with a differ= ent >> gas, CO2, and they rise again then switch over to O2 as photosynthesis >> picks up. >> >> It therefore seems likely that these leaves have some special surface >> coating that slows down gas exchange with the pond. Maybe they still >> retain stomata under the leaf which normally facilitate gas exchange for >> leaves in air, but these are modified to block or regulate gas exchange = in >> water? Maybe this is already known, just not to us here? >> Steve >> >> On Mar 10, 2018, at 10:45 AM, David <dwebster@glinx.com> wrote: >> >> Hi Nancy & All, >> I admit not having wondered about this but I think he makes a simple >> process complicated. The air pockets to which he refers are presumably >> intercellular spaces which in the absence of photosynthesis presumably c= an >> become water filled. Starch has a specific gravity of 1.5 g/mL and, in >> cooler weather starch will accumulate when respiration slows more than >> photosynthesis and the submarine will sink. With warming, growth resumes= , >> respiration and starch consumption rates increase and the submarine ris= es. >> Yt, DW, Kentville >> >> ------ Original Message ------ >> From: "nancy dowd" <nancypdowd@gmail.com> >> To: naturens@chebucto.ns.ca >> Sent: 3/10/2018 9:08:02 AM >> Subject: [NatureNS] Duckweed >> >> This is an interesting article on Duckweed seasonal disappearance and >> reappearance in the Spring 2018 issue of Northern Woodlands Magazine. >> https://northernwoodlands.org/outside_story/article/duckweed-migration >> >> I had never really thought about where it went in Fall or how it >> re-emerges in Spring. Such an important floating pond plant in >> productive fresh water >> >> Nancy D >> >> Sent from my iPad >> >> >> > > > -- > Nancy Robinson > 514-605-7186 <(514)%20605-7186> > > > --001a1141babadbc77b05673aa504 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">Having raised many waterfowl chicks at CWRC last summer, w= e always include duckweed in their diet and we had to look HARD for it last= year..whereas other years it was everywhere.<div><br></div><div>He