[NatureNS] tide times/amplitudes, mud shrimps & signs, etc., Blomidon Beach

To: NatureNS <naturens@chebucto.ns.ca>,
From: "James W. Wolford" <jimwolford@eastlink.ca>
Date: Thu, 18 Aug 2011 18:04:31 -0300
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--Boundary_(ID_yMG4VthJSQw2sP3jd5m6AA)
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AUG. 18, 2011 - Daytime high tide today 4:35 p.m. with a mediocre  
amplitude of 11.7 metres (cf. amplitude of 15.2 m. on Aug. 31).  Here  
are the next 13 days' worth of tide times and amplitudes. The times  
are for Horton Bluff, just east of Avonport.  Tides at Scots' Bay or  
Blomidon would be an hour to a half-hour earlier, and times toward  
Truro would be later and with higher amplitudes.  There are two highs  
and two lows every 24 hours and 50 minutes, so one cycle from high to  
high or low to low would be 12 hrs. 25 min., and from high to low or  
from low to high would be 6 hrs. 12 minutes.  Thus the other times  
can be easily approximated.  Remember too that the times and  
amplitudes are predictions and can actually vary considerably because  
of, for instance, atmospheric conditions and presence or absence of  
onshore or offshore winds of any strength.  (THANKS TO SHERMAN  
WILLIAMS for providing these data for the whole year in our Blomidon  
Naturalists Society Calendar for the past 15 years or so.)

	Aug. 19, Friday -- daytime h.t. 5:19 p.m. (11.0 metres)
	Aug. 20, Sat. -- d.h.t. 6:05 p.m. (10.2 m.)
	Aug. 21, Sun. -- dht  6:31 a.m. (9.3 m.)
	Aug. 22, Mon. -- dht 7:24 a.m. (8.6 m.)
	Aug. 23, Tues. --  dht 8:22 a.m. (8.2 m.)
	Aug. 24, Wed. -- dht 9:21 a.m. (8.3 m.)
	Aug. 25, Thurs. -- dht 10:18 a.m. (8.9 m.)
	Aug. 26, Fri. -- dht 11:12 a.m. (10.0 m.)
	Aug. 27, Sat. -- dht 12:03 p.m. (11.4 m.)
	Aug. 28, Sun. -- dht 12:51 p.m. (12.8 m.)
	Aug. 29, Mon. -- dht 1:38 p.m. (14.0 m.)
	Aug. 30, Tues. -- dht 2:24 p.m. (14.8 m.)
	Aug. 31, Wed. -- dht 3:11 p.m. (15.2 m.)

At low tide today I met Janet & John Foster again, this time at Cape  
Blomidon and Blomidon Provincial Park's beach area called White  
Waters, adjacent to the lower Park gate parking lot.  We met in late  
morning, with the tide out.  Like yesterday, I took them along the  
south edge of the main waterfall's outfall, and showed them the  
surface signs of soft-shelled clams and small Macoma clams.  But they  
really wanted to see the surface signs plus burrows and actual  
critters for the mud shrimps, Corophium volutator, which are small  
amphipod crustaceans that live in U-shaped burrows in the sandy-mud  
sediments of the upper and middle intertidal zones.

All I needed was a shovel to show all three of these organisms.  The  
burrow holes for the soft-shelled clams are quite large, but the  
holes for the Macoma clams are much smaller and show radiating  
feeding lines in a star-pattern on the surface.  For the mud shrimps  
the surface signs are several: (1) narrow curving trails from early  
in the ebbing tide when the male shrimps crawl over the wet surface  
and search for burrows inhabited by females (for sex, of course) 
(early in the feeding cycle the sandpipers feverishly hunt the  
surface for these crawling males); (2) tracks of the small sandpipers  
are usually present, too; (3) lots of small surface holes, which are  
entrances and exits for water currents from the filter-feeding mud  
shrimps in the burrows when the tide is in; (4) revealed by the  
shovel, the U-shaped burrows containing the mud shrimps themselves,  
which at this time of year tend to be quite small (a huge one would  
be 1 cm. long); and (5) variably sized circular shallow excavations  
in the surface sediment, from bottom-feeding fishes like flounders  
and skates that show up when the tide gets high.  These feeding  
depressions from the fishes are excellent clues as to where the  
sediments contain a lot of food critters!

John & Janet & I had to dig many times in order to find the right  
angles and right camera/lens plus cooperative mud shrimps for the  
high-definition footage they wanted.  Hopefully that was achieved,  
and not too many critters died for educational reasons!

Thus a good time to look for them would be early in the ebbing tide  
when the mud is still wet.  When male and female get together, they  
can amplex like frogs and toads do, and then the male fertilizes the  
eggs externally as the female releases them into her brood pouch,  
where she will carry them around until the eggs hatch.

Other intertidal life there on the rocks just above the outfall on  
the upper beach were loads of barnacles, which don't look like  
crustaceans but really are so, and oodles of common periwinkle  
snails, plus a few kinds of small seaweeds.

One weird sighting occurred while we were on the Blomidon beach at  
low tide: 2 or 3 double-crested cormorants repeatedly flew along the  
beach, back and forth, at low altitude and seemed to be interested in  
us people who were on the beach.

We didn't see any shorebirds there today, but yesterday the Fosters  
did see about 10 peeps there.  Other birds seen were an adult bald  
eagle, 2+ ravens, about 20 mixed gulls, and, on the power lines along  
the road to get there, oodles of starlings in flocks.

Cheers from Jim in Wolfville

--Boundary_(ID_yMG4VthJSQw2sP3jd5m6AA)
Content-type: text/html; CHARSET=US-ASCII
Content-transfer-encoding: quoted-printable

<html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; "><div style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica"><b>AUG. =
18, 2011</b> - Daytime <b>high tide today 4:35 p.m. </b>with a mediocre =
amplitude of 11.7 metres (cf. amplitude of 15.2 m. on Aug. 31).&nbsp; =
Here are the <b>next 13 days' worth of tide times and amplitudes</b>. =
The times are for Horton Bluff, just east of Avonport.&nbsp; Tides at =
Scots' Bay or Blomidon would be an hour to a half-hour earlier, and =
times toward Truro would be later and with higher amplitudes.&nbsp; =
There are two highs and two lows every 24 hours and 50 minutes, so one =
cycle from high to high or low to low would be 12 hrs. 25 min., and from =
high to low or from low to high would be 6 hrs. 12 minutes.&nbsp; Thus =
the other times can be easily approximated.&nbsp; Remember too that the =
times and amplitudes are predictions and can actually vary considerably =
because of, for instance, atmospheric conditions and presence or absence =
of onshore or offshore winds of any strength.&nbsp; (THANKS TO SHERMAN =
WILLIAMS for providing these data for the whole year in our Blomidon =
Naturalists Society Calendar for the past 15 years or =
so.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre">	</span>Aug. 19, Friday -- daytime h.t. =
5:19 p.m. (11.0 metres)</font></div><div style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre">	</span>Aug. 20, =
Sat. -- d.h.t. 6:05 p.m. (10.2 m.)</font></div><div style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre">	</span>Aug. 21, =
Sun. -- dht&nbsp; 6:31 a.m. (9.3 m.)</font></div><div style=3D"margin-top:=
 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre">	</span>Aug. 22, =
Mon. -- dht 7:24 a.m. (8.6 m.)</font></div><div style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre">	</span>Aug. 23, =
Tues. --&nbsp; dht 8:22 a.m. (8.2 m.)</font></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre">	</span>Aug. 24, Wed. -- dht 9:21 a.m. =
(8.3 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 25, Thurs. -- dht 10:18 a.m. =
(8.9 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 26, Fri. -- dht 11:12 a.m. =
(10.0 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 27, Sat. -- dht 12:03 p.m. =
(11.4 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 28, Sun. -- dht 12:51 p.m. =
(12.8 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 29, Mon. -- dht 1:38 p.m. =
(14.0 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 30, Tues. -- dht 2:24 p.m. =
(14.8 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><span class=3D"Apple-tab-span"=
 style=3D"white-space:pre">	</span>Aug. 31, Wed. -- dht 3:11 p.m. =
(15.2 m.)</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica">At low tide today I met Janet &amp; John Foster again, =
this time at Cape Blomidon and Blomidon Provincial Park's beach area =
called White Waters, adjacent to the lower Park gate parking lot.&nbsp; =
We met in late morning, with the tide out.&nbsp; Like yesterday, I took =
them along the south edge of the main waterfall's outfall, and showed =
them the surface signs of <b>soft-shelled clams</b> and small <i>Macoma =
</i><b>clams</b>.&nbsp; But they really wanted to see the surface signs =
plus burrows and actual critters for the <b>mud shrimps</b>, =
<i>Corophium volutator</i>, which are small amphipod crustaceans that =
live in U-shaped burrows in the sandy-mud sediments of the upper and =
middle intertidal zones. &nbsp;</font></div><div style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: =
normal normal normal 12px/normal Helvetica; min-height: 14px; =
"><br></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">All I needed was a shovel to =
show all three of these organisms.&nbsp; The burrow holes for the =
soft-shelled clams are quite large, but the holes for the Macoma clams =
are much smaller and show radiating feeding lines in a star-pattern on =
the surface.&nbsp;<b> For the mud shrimps the surface signs are several: =
</b>(1) narrow curving trails from early in the ebbing tide when the =
male shrimps crawl over the wet surface and search for burrows inhabited =
by females (for sex, of course)(early in the feeding cycle the =
sandpipers feverishly hunt the surface for these crawling males); (2) =
tracks of the small sandpipers are usually present, too; (3) lots of =
small surface holes, which are entrances and exits for water currents =
from the filter-feeding mud shrimps in the burrows when the tide is in; =
(4) revealed by the shovel, the U-shaped burrows containing the mud =
shrimps themselves, which at this time of year tend to be quite small (a =
huge one would be 1 cm. long); and (5) variably sized circular shallow =
excavations in the surface sediment, from bottom-feeding fishes like =
flounders and skates that show up when the tide gets high.&nbsp; =
These<b> feeding depressions from the fishes</b> are excellent clues as =
to where the sediments contain a lot of food critters! =
&nbsp;</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><br></font></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica"><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">John &amp; Janet &amp; I had =
to dig many times in order to find the right angles and right =
camera/lens plus cooperative mud shrimps for the high-definition footage =
they wanted.&nbsp; Hopefully that was achieved, and not too many =
critters died for educational =
reasons!&nbsp;</font></div></font></div><div style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal =
normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica">Thus a good time to look for them would be early in =
the ebbing tide when the mud is still wet.&nbsp; When male and female =
get together, they can amplex like frogs and toads do, and then the male =
fertilizes the eggs externally as the female releases them into her =
brood pouch, where she will carry them around until the eggs =
hatch.&nbsp;</font></div><div style=3D"margin-top: 0px; margin-right: =
0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica"><b>Other intertidal life</b> there on the rocks just =
above the outfall on the upper beach were loads of <b>barnacles</b>, =
which don't look like crustaceans but really are so, and oodles of =
<b>common periwinkle snails</b>, plus a few kinds of small =
seaweeds.</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica">One weird sighting occurred while we were on the =
Blomidon beach at low tide: <b>2 or 3 double-crested cormorants</b> =
repeatedly flew along the beach, back and forth, at low altitude and =
seemed to be interested in us people who were on the beach. =
&nbsp;</font></div><div style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><br></div><div =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" style=3D"font: =
12.0px Helvetica">We didn't see any <b>shorebirds</b> there today, but =
yesterday the Fosters did see about 10 peeps there.&nbsp;<b> Other =
birds</b> seen were an adult bald eagle, 2+ ravens, about 20 mixed =
gulls, and, on the power lines along the road to get there, oodles of =
starlings in flocks.</font></div><div style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px =
Helvetica"><br></font></div><div style=3D"margin-top: 0px; margin-right: =
0px; margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica">Cheers from Jim in =
Wolfville</font></div>
</body></html>=

--Boundary_(ID_yMG4VthJSQw2sP3jd5m6AA)--

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