1
00:00:06,260 --> 00:00:10,240
Welcome to the second talk
2
00:00:10,240 --> 00:00:12,240
of Shared Science.
3
00:00:12,240 --> 00:00:16,240
I would like to comment before starting
4
00:00:16,240 --> 00:00:22,240
that these talks are authorized to be public,
5
00:00:22,240 --> 00:00:27,440
they will be on Repositorio Institucional of the university, Acceda.
6
00:00:27,440 --> 00:00:31,370
They are now also available on the Youtube channel
7
00:00:31,370 --> 00:00:33,400
of the Biblioteca Universitaria.
8
00:00:33,400 --> 00:00:36,880
Here is our first speaker,
9
00:00:38,460 --> 00:00:44,460
Federico Maldonado, who will go down in history.
10
00:00:53,860 --> 00:00:57,000
The idea is that we all know
11
00:00:57,000 --> 00:00:59,000
a little of what is done in
12
00:00:59,000 --> 00:01:01,000
each group of the faculty,
13
00:01:01,000 --> 00:01:03,000
which researches are made,
14
00:01:03,000 --> 00:01:05,000
to know each other
15
00:01:07,000 --> 00:01:09,420
and to share it, because it is not only the sea
16
00:01:09,420 --> 00:01:11,670
but also some do coastal things
17
00:01:11,670 --> 00:01:13,130
and we want them to participate.
18
00:01:13,130 --> 00:01:15,130
We also want to know
19
00:01:15,130 --> 00:01:17,130
if you have any doubts as well or you want
20
00:01:17,130 --> 00:01:19,130
to contribute, to share it,
21
00:01:19,130 --> 00:01:21,130
because sometimes we are too focused on
22
00:01:21,130 --> 00:01:24,130
respiration, in Fede's case, or in my case
23
00:01:24,130 --> 00:01:26,280
on currents and we forget about the rest
24
00:01:26,280 --> 00:01:28,280
and maybe things from the outside
25
00:01:28,280 --> 00:01:30,280
could help us.
26
00:01:30,980 --> 00:01:36,660
The idea is also to encourage students
27
00:01:36,660 --> 00:01:38,660
to come to these talks,
28
00:01:38,660 --> 00:01:41,970
to show the use of what you are learning.
29
00:01:42,970 --> 00:01:50,280
And Avelina is in charge to inform you.
30
00:01:53,680 --> 00:01:57,680
This was for you to see what is going on.
31
00:02:04,980 --> 00:02:09,480
Then we have here our second speaker,
32
00:02:12,330 --> 00:02:15,060
that will talk about
33
00:02:15,060 --> 00:02:19,260
migration and trophic ecology of vertical migrant
34
00:02:19,260 --> 00:02:22,500
fishes that dominate subtropical Northeast Atlantic.
35
00:02:22,500 --> 00:02:25,200
Involvement on active carbon flux.
36
00:02:25,200 --> 00:02:27,840
I believe that you all know him,
37
00:02:27,840 --> 00:02:31,510
Alejandro Ariza, he studied biology
38
00:02:31,510 --> 00:02:33,240
in the Universidad de La Laguna.
39
00:02:33,240 --> 00:02:35,640
And he specialised in marine biology,
40
00:02:35,640 --> 00:02:38,840
and there he began with his research;
41
00:02:38,840 --> 00:02:43,240
that he later continued in th ULPGC,
42
00:02:43,240 --> 00:02:46,370
signed by Santiago Hernández León.
43
00:02:46,770 --> 00:02:50,840
He works now on inter-zonal migrants
44
00:02:50,840 --> 00:02:53,310
that live in mesopelagic waters
45
00:02:53,310 --> 00:02:59,300
and I quote what he told me before:
46
00:02:59,300 --> 00:03:02,150
"We are interested in the exportation of carbon
47
00:03:02,150 --> 00:03:05,480
that those organisms do when they migrate.
48
00:03:05,480 --> 00:03:08,110
This has to do with the biological pump
49
00:03:08,110 --> 00:03:10,110
of the ocean, a complex mechanism
50
00:03:10,110 --> 00:03:13,130
that the ocean takes CO2 from the atmosphere,
51
00:03:13,130 --> 00:03:15,750
something that is very interesting in this
52
00:03:15,750 --> 00:03:17,950
global change scenario that we are living in".
53
00:03:18,250 --> 00:03:21,550
This is a little part of what he is going to tell us,
54
00:03:21,550 --> 00:03:24,750
and he also works between
55
00:03:24,750 --> 00:03:27,650
the ULPGC, with Santiago Hernández,
56
00:03:27,650 --> 00:03:32,150
and the Instituto Canario de Ciencias Marinas
57
00:03:32,150 --> 00:03:34,550
with Fernando Bordes Caballero,
58
00:03:34,550 --> 00:03:37,600
in terms of acoustic and he has stayed
59
00:03:37,600 --> 00:03:39,600
the last one in Norway,
60
00:03:39,600 --> 00:03:42,600
in an institute working on
61
00:03:42,600 --> 00:03:45,900
acoustics and he has just embarked
62
00:03:45,900 --> 00:03:51,400
in the Ramón Magalef to work in the volcanic
63
00:03:51,400 --> 00:03:53,400
crisis in El Hierro.
64
00:03:53,400 --> 00:03:56,700
Nothing else Alejandro, it is all yours.
65
00:03:56,700 --> 00:04:00,700
Thanks Avelina, you saved me a lot of explanations.
66
00:04:02,700 --> 00:04:04,700
I want to say that in this work
67
00:04:04,700 --> 00:04:08,030
other people has collaborated,
68
00:04:08,030 --> 00:04:12,330
Rupert William Reuter, Fernando Bordes Caballero
69
00:04:12,330 --> 00:04:14,330
from the Instituto Canario de Ciencias Marinas
70
00:04:14,330 --> 00:04:16,330
and Santiago, the head.
71
00:04:16,330 --> 00:04:21,830
The research of migration and trophic ecology
72
00:04:23,830 --> 00:04:27,950
address the implication of these organisms
73
00:04:27,950 --> 00:04:30,250
on the active flux efficience.
74
00:04:30,250 --> 00:04:33,050
In this work we want to focus on this especially.
75
00:04:33,050 --> 00:04:35,050
Well, let's start.
76
00:04:37,050 --> 00:04:40,050
I would like to begin with this image,
77
00:04:40,050 --> 00:04:42,050
this is an echogram,
78
00:04:42,050 --> 00:04:45,350
where we can see a migration process.
79
00:04:45,350 --> 00:04:47,350
What you can see down here is
80
00:04:47,350 --> 00:04:49,350
the Deep scattering layer
81
00:04:49,350 --> 00:04:51,250
and it is produced by the echo
82
00:04:51,250 --> 00:04:53,440
that pelagic organisms make
83
00:04:53,440 --> 00:04:56,740
that live between 400 and 700 mts deep.
84
00:04:56,940 --> 00:04:59,640
What you see up here is the migrant layer,
85
00:04:59,640 --> 00:05:03,110
and its a part of the same organisms
86
00:05:03,110 --> 00:05:04,610
that emigrate when it gets darker
87
00:05:04,610 --> 00:05:07,820
to eat epipelagic plankton in the in the surface.
88
00:05:07,820 --> 00:05:09,820
When the dawn comes, they come back
89
00:05:09,820 --> 00:05:12,110
again to deeper layers to protect themselves
90
00:05:12,110 --> 00:05:14,110
in the darkness from predation.
91
00:05:14,810 --> 00:05:18,240
This is called diel vertical migration,
92
00:05:20,240 --> 00:05:22,440
that is how in scientific articles is seen.
93
00:05:22,440 --> 00:05:27,840
And this phenomenon happens globally
94
00:05:27,840 --> 00:05:30,340
every night.
95
00:05:30,340 --> 00:05:32,820
This has a great importance in the trophic
96
00:05:32,820 --> 00:05:34,820
connection between organisms
97
00:05:34,820 --> 00:05:37,020
of the surface and the deeper ocean.
98
00:05:37,620 --> 00:05:40,020
That is why it has strong implications
99
00:05:40,020 --> 00:05:42,020
on carbon.
100
00:05:42,020 --> 00:05:44,620
These animals eat in the surface
101
00:05:44,620 --> 00:05:46,620
the organic carbon produced there,
102
00:05:46,620 --> 00:05:48,620
they transport it to intermediate layers,
103
00:05:48,620 --> 00:05:50,620
and they release it in form of
104
00:05:50,620 --> 00:05:52,860
carbon dioxide when they breath
105
00:05:52,860 --> 00:05:55,160
or these types of organic carbon
106
00:05:55,160 --> 00:05:59,160
when defecating, excreting or when they are predated.
107
00:05:59,160 --> 00:06:02,560
This active transportation of carbon
108
00:06:02,560 --> 00:06:04,030
by the migrators,
109
00:06:04,030 --> 00:06:06,460
is what we called active carbon flux,
110
00:06:06,460 --> 00:06:08,460
and with another important mechanism,
111
00:06:08,460 --> 00:06:11,530
that is the gravitational flux o passive flux,
112
00:06:11,530 --> 00:06:14,330
both are part of the biologic pump of carbon;
113
00:06:14,330 --> 00:06:16,110
that is a complex system
114
00:06:16,110 --> 00:06:20,080
that takes carbon dioxide from the atmosphere and now is more important
115
00:06:20,080 --> 00:06:22,080
due to climate change.
116
00:06:22,880 --> 00:06:25,380
Who are these migrators?
117
00:06:25,380 --> 00:06:27,620
Traditionally from the perspective of the
118
00:06:27,620 --> 00:06:28,730
biogeochemical oceanology,
119
00:06:28,730 --> 00:06:31,130
when we talk about migrators and active flux
120
00:06:31,130 --> 00:06:33,730
zooplankton is the first that comes to everyone's mind.
121
00:06:33,730 --> 00:06:36,230
I would like today to talk about another type
122
00:06:36,230 --> 00:06:38,230
that is the one that I work with, the micronekton;
123
00:06:38,230 --> 00:06:41,160
that are mainly fishes, crustaceans, cephalopods
124
00:06:41,160 --> 00:06:44,460
between 2 and 10 centimeters of size.
125
00:06:44,460 --> 00:06:47,460
They are migrators, like the zooplankton
126
00:06:47,460 --> 00:06:49,160
however they have been excluded
127
00:06:49,160 --> 00:06:51,160
of the active flux counts.
128
00:06:51,160 --> 00:06:53,160
This is like this, because
129
00:06:53,160 --> 00:06:56,160
these animals escape easily
130
00:06:56,160 --> 00:06:59,160
from the nets that are used for plankton.
131
00:06:59,160 --> 00:07:01,160
They evade them, they do not escape.
132
00:07:02,060 --> 00:07:05,360
Moreover they are little enough to
133
00:07:05,360 --> 00:07:07,360
escape from the commercial trawl nets.
134
00:07:07,960 --> 00:07:11,860
The last ones, although they get something,
135
00:07:11,860 --> 00:07:15,330
they are rare in oceanographic campaigns,
136
00:07:15,330 --> 00:07:17,030
because they consume a lot of time.
137
00:07:17,030 --> 00:07:21,030
That is why they have been excluded from the research
138
00:07:21,030 --> 00:07:21,910
of active flux.
139
00:07:21,910 --> 00:07:24,710
Nevertheless we think that it is important,
140
00:07:24,710 --> 00:07:27,910
because micronekton is able to
141
00:07:27,910 --> 00:07:32,610
control 5-10% of the diary production of zooplanknton.
142
00:07:33,410 --> 00:07:36,610
Furthermore, the majority of this micronekton is
143
00:07:36,610 --> 00:07:39,610
formed from the Myctophidae family
144
00:07:39,610 --> 00:07:43,110
that 70% of the migrant biomass are myctophids,
145
00:07:43,110 --> 00:07:45,910
and a 75% of the mesopelagic capture
146
00:07:45,910 --> 00:07:48,210
in a trawling, they are also these fishes.
147
00:07:48,210 --> 00:07:52,550
The global stock is estimated at 500 to 600 million tonnes.
148
00:07:52,550 --> 00:07:55,020
and probably understimated,
149
00:07:55,020 --> 00:07:57,920
because escapes are not considered.
150
00:07:59,920 --> 00:08:02,320
That is why we think that myctophids must
151
00:08:02,320 --> 00:08:04,320
represent an important route in the
152
00:08:04,320 --> 00:08:06,320
exportation of organic carbon to
153
00:08:06,320 --> 00:08:08,320
deeper waters.
154
00:08:08,820 --> 00:08:12,000
One issue that has always been a hotly debated one is
155
00:08:12,000 --> 00:08:14,000
the efficiency of the exportation of carbon
156
00:08:14,000 --> 00:08:16,000
of the migrators, due to that
157
00:08:16,000 --> 00:08:18,640
range that they do in these migrations.
158
00:08:18,640 --> 00:08:20,940
Because they are the inter-zonal migrations,
159
00:08:20,940 --> 00:08:22,940
represented in red,
160
00:08:22,940 --> 00:08:25,100
the ones that get through the barriers,
161
00:08:25,100 --> 00:08:28,350
barriers to the exchange of water bodies;
162
00:08:28,350 --> 00:08:30,350
are the ones that are considered efficient
163
00:08:30,350 --> 00:08:31,650
in the carbon exportation.
164
00:08:31,650 --> 00:08:34,950
Trying to move it from a compartment to another in the ocean.
165
00:08:35,650 --> 00:08:38,700
Moreover, the time that they need to come back to the deep
166
00:08:38,950 --> 00:08:40,350
layer must be smaller
167
00:08:40,350 --> 00:08:42,350
than the time that need the food
168
00:08:42,350 --> 00:08:44,350
to be processed and to be evacuated.
169
00:08:44,350 --> 00:08:46,530
If we want that a minimun of what they consume
170
00:08:46,530 --> 00:08:49,600
in the surface to be transported to deeper waters.
171
00:08:51,600 --> 00:08:53,600
That is why studying the migration
172
00:08:53,600 --> 00:08:55,770
and the food chronology is important
173
00:08:55,770 --> 00:08:58,270
to study the active flux.
174
00:08:59,270 --> 00:09:02,040
This is the way we have worked on those two issues,
175
00:09:02,340 --> 00:09:05,040
along with diet, which we have also worked on,
176
00:09:05,040 --> 00:09:07,750
and the daily ration
177
00:09:07,750 --> 00:09:11,220
the amount of body weight they ingest.
178
00:09:12,220 --> 00:09:14,550
We have done this in Hygophum hygomi,
179
00:09:14,550 --> 00:09:16,550
Lobianchia dofleini, two myctophids
180
00:09:16,550 --> 00:09:19,550
that dominate the Subtropical Northeast Atlantic.
181
00:09:20,550 --> 00:09:23,400
As I told you, micronekton does not abound
182
00:09:23,400 --> 00:09:25,600
too much in oceanographic campaigns,
183
00:09:25,600 --> 00:09:28,600
thanks to some cooperation with the
184
00:09:28,600 --> 00:09:31,480
Instituto Canario de Ciencia Marinas thanks to Fernando Bordes.
185
00:09:31,480 --> 00:09:34,980
We worked with help
186
00:09:34,980 --> 00:09:37,910
coming from some campaigns of fishing
187
00:09:37,910 --> 00:09:41,210
prospections, that were done between 1997 and 2002,
188
00:09:41,210 --> 00:09:43,880
with a poop trawling, using a trawling
189
00:09:43,880 --> 00:09:45,880
comercial semipelagic net.
190
00:09:46,880 --> 00:09:50,880
We chose sets done in Fuerteventura,
191
00:09:50,880 --> 00:09:53,680
because those catches were from different times.
192
00:09:53,680 --> 00:09:55,680
This is appropiated for this study
193
00:09:55,680 --> 00:09:58,380
of mmigration because it is a
194
00:09:58,380 --> 00:10:02,380
phenomenon that occur in a 24 hours cycle.
195
00:10:02,880 --> 00:10:05,280
We did not take every set that was done.
196
00:10:05,280 --> 00:10:08,080
We used only the ones interesting for the study,
197
00:10:08,080 --> 00:10:10,480
we prefered to work with epipelagic sets
198
00:10:10,480 --> 00:10:13,480
that we defined between 0 and 150 meters of depth.
199
00:10:13,780 --> 00:10:17,100
We got 9 sets,
200
00:10:17,100 --> 00:10:19,790
in a 24 hours cycle.
201
00:10:19,790 --> 00:10:22,240
The black colour represents the night hours
202
00:10:22,240 --> 00:10:24,040
and blue the light hours.
203
00:10:24,640 --> 00:10:26,870
The mesopelagic sets were defined
204
00:10:26,870 --> 00:10:29,370
between 300 and 700 meters of depth.
205
00:10:29,370 --> 00:10:31,370
We got 6 sets,
206
00:10:31,370 --> 00:10:33,870
distributed this other way in 24 hours.
207
00:10:34,270 --> 00:10:36,870
We took all data of abundance of these two
208
00:10:36,870 --> 00:10:39,170
species, we standardised it to 10.000 cubic meters,
209
00:10:39,170 --> 00:10:41,470
and we computed it in a histogram
210
00:10:41,470 --> 00:10:43,470
in 24 hours
211
00:10:43,470 --> 00:10:45,910
to visualise the migration phenomenon well.
212
00:10:47,210 --> 00:10:49,910
For us in food chronology,
213
00:10:49,910 --> 00:10:52,550
we could not use the samples from Fuerteventura,
214
00:10:52,550 --> 00:10:54,750
that we have the abundance data,
215
00:10:54,750 --> 00:10:56,750
but the samples were distributed in
216
00:10:56,750 --> 00:10:57,820
museums around the world.
217
00:10:57,820 --> 00:11:00,470
We have ordered them and we have them already in laboratory.
218
00:11:00,470 --> 00:11:02,470
We are working them, however
219
00:11:02,470 --> 00:11:04,470
we do not have yet the final product.
220
00:11:04,470 --> 00:11:06,470
Here are the data from
221
00:11:06,470 --> 00:11:08,470
other zone where we analyse
222
00:11:08,470 --> 00:11:11,130
food chronology with the same methodology,
223
00:11:11,430 --> 00:11:14,230
in which we studied individuals
224
00:11:14,230 --> 00:11:16,630
of the mesopelagic layer
225
00:11:16,930 --> 00:11:19,730
a bit before the nightfall
226
00:11:19,730 --> 00:11:22,210
some hours befor the next migration.
227
00:11:22,210 --> 00:11:24,310
We studied their stomach contents.
228
00:11:24,310 --> 00:11:27,040
These individuals are considered premigrators.
229
00:11:27,040 --> 00:11:29,340
We also studied the stomachs of individuals
230
00:11:29,340 --> 00:11:31,540
that we consider postmigrators,
231
00:11:31,540 --> 00:11:33,640
that were caught in the epipelagic layer,
232
00:11:33,640 --> 00:11:36,640
some hours after the nightfall.
233
00:11:38,640 --> 00:11:40,840
This is the procedure of extraction
234
00:11:40,840 --> 00:11:43,350
from the stomach of the myctophids.
235
00:11:43,350 --> 00:11:45,350
This is the look of the
236
00:11:45,350 --> 00:11:47,350
stomach of anLobianchia dofleini.
237
00:11:47,350 --> 00:11:49,850
This is even smaller than a
238
00:11:49,850 --> 00:11:52,740
grain of rice, so we have to be careful while dissecting it.
239
00:11:52,740 --> 00:11:54,740
This is an open stomach.
240
00:11:54,740 --> 00:11:56,740
In this case is really full.
241
00:11:56,940 --> 00:12:00,390
I selected this one because it is very fresh
242
00:12:00,390 --> 00:12:02,990
and it is not what I normally found, but
243
00:12:02,990 --> 00:12:05,240
I chose the one with the freshest content
244
00:12:05,240 --> 00:12:07,240
because is better for the picture,
245
00:12:07,240 --> 00:12:09,000
we can see them perfectly.
246
00:12:09,000 --> 00:12:11,800
It is completely full of copepods.
247
00:12:12,300 --> 00:12:17,200
And this is the compound eye.
248
00:12:19,200 --> 00:12:21,900
Then for the food chronology study
249
00:12:21,900 --> 00:12:23,900
we used two scales.
250
00:12:23,900 --> 00:12:27,400
A stomach fullness scale,
251
00:12:27,400 --> 00:12:30,400
that went from the stage 0
252
00:12:30,400 --> 00:12:31,840
where the stomach was full,
253
00:12:31,840 --> 00:12:34,640
to the stage 3, where it has been totally full.
254
00:12:34,640 --> 00:12:37,140
In addition to considering the filling of the stomach,
255
00:12:37,140 --> 00:12:39,140
we consider the roughness state of
256
00:12:39,140 --> 00:12:40,860
the internal pallets of the stomach,
257
00:12:40,860 --> 00:12:44,450
when the stomach is very full, the roughness disappears.
258
00:12:44,450 --> 00:12:47,770
And as we study the digestion of contents
259
00:12:47,770 --> 00:12:52,670
we did it only on copepods, because we
260
00:12:52,670 --> 00:12:55,800
assume that each group must have
261
00:12:55,800 --> 00:12:58,100
a different rate of digestion,
262
00:12:58,100 --> 00:13:00,750
to avoid this mistake, we only talk about one group.
263
00:13:00,750 --> 00:13:03,150
The copepods because they are the most commonly found,
264
00:13:03,150 --> 00:13:08,850
Then stage 1 is a fresh copepod,
265
00:13:08,850 --> 00:13:11,850
in Stage 2, has the appendices
266
00:13:11,850 --> 00:13:14,760
broken, but the main part of the body is well preserved;
267
00:13:14,760 --> 00:13:16,760
and in stage 3, it has the main part
268
00:13:16,760 --> 00:13:18,760
of the body very deteriorated.
269
00:13:18,960 --> 00:13:22,060
On both scales what we want to know
270
00:13:22,060 --> 00:13:24,060
at what time are they eating
271
00:13:24,060 --> 00:13:26,760
and how long it takes them to digest the food.
272
00:13:27,960 --> 00:13:30,760
In order to study the diet, what we did is to take
273
00:13:30,760 --> 00:13:33,260
contents of animals on the surface
274
00:13:33,260 --> 00:13:35,330
at 12 p.m. because they were eating at that time.
275
00:13:35,330 --> 00:13:37,130
Then they had the fresh contents,
276
00:13:37,130 --> 00:13:39,130
y esto venía bien para estudiar
277
00:13:39,130 --> 00:13:42,530
the contents rather than the digested ones.
278
00:13:42,530 --> 00:13:45,280
And for the study of the daily ration,
279
00:13:45,280 --> 00:13:47,780
we look at stomachs listed as
280
00:13:47,780 --> 00:13:49,780
maximum filling stage,
281
00:13:49,780 --> 00:13:52,080
and the data is expressed as a percentage
282
00:13:52,080 --> 00:13:55,580
of the animal's body weight with what it is ingesting.
283
00:13:57,580 --> 00:13:59,880
Well, let's see the results.
284
00:13:59,880 --> 00:14:02,880
These are the results of abundance.
285
00:14:02,880 --> 00:14:05,670
In the mesopelagic layer and in the epipelagic layer,
286
00:14:05,670 --> 00:14:07,870
for Hygophum hygomi and Lobianchia dofleini.
287
00:14:07,870 --> 00:14:09,870
These shaded areas represent
288
00:14:09,870 --> 00:14:11,870
the night periods.
289
00:14:11,870 --> 00:14:13,870
The first thing we see is
290
00:14:13,870 --> 00:14:15,870
that even though daylight fishing was analysed
291
00:14:15,870 --> 00:14:17,370
in the epipelagic layer,
292
00:14:17,370 --> 00:14:19,730
as expected did not register
293
00:14:19,730 --> 00:14:22,430
neither species.
294
00:14:22,430 --> 00:14:24,730
Not even the first
295
00:14:24,730 --> 00:14:26,730
half hour after the nightfall
296
00:14:26,730 --> 00:14:29,630
tampoco aparecen, se demoran un poco más en subir.
297
00:14:31,990 --> 00:14:34,630
This 0 individuals,
298
00:14:34,630 --> 00:14:37,130
and between 9pm and 1pm,
299
00:14:37,130 --> 00:14:40,030
both species have the highest abundance.
300
00:14:40,030 --> 00:14:42,030
Moreover, what we see is that
301
00:14:42,030 --> 00:14:44,030
in the case of the Lobianchia dofleini especially,
302
00:14:44,030 --> 00:14:45,240
se ve que hay una
303
00:14:45,240 --> 00:14:47,240
progressive decrease in abundance
304
00:14:47,240 --> 00:14:49,240
as the night progresses
305
00:14:49,240 --> 00:14:51,240
and with a peak of abundance
306
00:14:51,240 --> 00:14:53,540
in the lower layers.
307
00:14:53,940 --> 00:14:58,620
The pattern of no individuals here
308
00:14:58,620 --> 00:14:59,900
and at night they appear,
309
00:14:59,900 --> 00:15:02,200
is a normal migration pattern
310
00:15:02,200 --> 00:15:04,600
of night migration
311
00:15:04,600 --> 00:15:06,900
al anochecer en sentido ascendente,
312
00:15:06,900 --> 00:15:09,400
which has been well documented for years.
313
00:15:09,800 --> 00:15:11,910
And the issue of abundance growth
314
00:15:11,910 --> 00:15:14,650
together with late onset in lower layers,
315
00:15:14,650 --> 00:15:16,650
may be a phenomenon
316
00:15:16,650 --> 00:15:18,650
of midnight sinking.
317
00:15:18,650 --> 00:15:20,650
This is a hypothesis postulated by Pearre,
318
00:15:20,650 --> 00:15:21,800
in which he states that
319
00:15:21,800 --> 00:15:24,320
these individuals do not migrate in a massive way,
320
00:15:24,320 --> 00:15:26,820
do not descend in a massive way at dawn,
321
00:15:26,820 --> 00:15:28,820
but they do it in a way,
322
00:15:28,820 --> 00:15:30,820
asynchronous in some way
323
00:15:30,820 --> 00:15:33,020
individual as they feel satiated.
324
00:15:33,020 --> 00:15:35,560
When their stomachs are full, they decide to go down.
325
00:15:35,560 --> 00:15:38,420
As this is an individual phenomenon,
326
00:15:38,420 --> 00:15:40,420
it does not register very well with the
327
00:15:40,420 --> 00:15:43,920
traditional acoustic techniques.
328
00:15:43,920 --> 00:15:47,260
That is why this has not been discussed until now.
329
00:15:50,080 --> 00:15:53,260
If we look at the captures of the mesopelagic layer,
330
00:15:53,260 --> 00:15:56,260
we see that there is presence by day and by night.
331
00:15:56,260 --> 00:15:58,760
We are interested the most in
332
00:15:58,760 --> 00:16:00,960
is the presence during the night, because
333
00:16:00,960 --> 00:16:03,960
it may be the result of this sinking.
334
00:16:03,960 --> 00:16:05,960
But also a number of individuals
335
00:16:05,960 --> 00:16:07,960
who are simply not migrating.
336
00:16:07,960 --> 00:16:09,960
If you remember the image we saw
337
00:16:09,960 --> 00:16:11,960
at the beginning of the talk,
338
00:16:12,460 --> 00:16:14,960
when the migrant layer rises during the night,
339
00:16:14,960 --> 00:16:16,960
the deep layer does not disappear.
340
00:16:16,960 --> 00:16:19,560
This is not new, it has been known for a long time.
341
00:16:19,560 --> 00:16:21,560
It used to be thought that the
342
00:16:21,560 --> 00:16:24,060
species in this layer were non-migratory.
343
00:16:24,460 --> 00:16:27,360
The presence of these individuals means that
344
00:16:27,360 --> 00:16:29,860
are migratory species that choose not to migrate.
345
00:16:30,460 --> 00:16:32,310
What we are interested in is knowing
346
00:16:32,310 --> 00:16:35,300
what the motive is and what they are doing there.
347
00:16:36,800 --> 00:16:39,500
If we look at the results of stomach filling,
348
00:16:39,500 --> 00:16:41,950
we see that as we expected,
349
00:16:41,950 --> 00:16:43,950
individuals who we consider to be
350
00:16:43,950 --> 00:16:45,380
migrating on the surface,
351
00:16:45,380 --> 00:16:47,380
most of them have full stomachs and
352
00:16:47,380 --> 00:16:49,780
seedlings; this is due to what we already know
353
00:16:49,780 --> 00:16:52,480
that they eat at night on the surface.
354
00:16:52,480 --> 00:16:56,330
However, organisms in the mesopelagic layer
355
00:16:56,330 --> 00:16:58,330
are just hours away from migrating again,
356
00:16:58,330 --> 00:17:00,330
we hope they had empty stomachs,
357
00:17:00,330 --> 00:17:02,830
because most of them have full stomachs.
358
00:17:02,830 --> 00:17:04,830
We found this rather strange
359
00:17:04,830 --> 00:17:06,830
and in the bibliography you will find
360
00:17:06,830 --> 00:17:08,830
some references that
361
00:17:08,830 --> 00:17:11,590
they eat during the day in the mesopelagic layer,
362
00:17:11,590 --> 00:17:14,990
as postulated by Pearcy for myctophids in the Pacific.
363
00:17:15,990 --> 00:17:19,290
However, on the basis of the digestion results,
364
00:17:19,590 --> 00:17:22,490
we see that individuals do indeed,
365
00:17:22,490 --> 00:17:24,890
that are migrating are at the surface,
366
00:17:24,890 --> 00:17:26,890
as most of them have stomachs
367
00:17:26,890 --> 00:17:28,490
full of fresh prey.
368
00:17:28,490 --> 00:17:31,390
If not, let alone in a state of advanced digestion.
369
00:17:31,390 --> 00:17:33,390
In case of theLobianchia dofleini,
370
00:17:33,390 --> 00:17:35,690
we find less prey, less copepods,
371
00:17:35,690 --> 00:17:37,690
because they ingested fewer copepods.
372
00:17:37,690 --> 00:17:39,690
But there are still more fresh prey,
373
00:17:39,690 --> 00:17:42,800
no prey at maximum digestible state.
374
00:17:42,800 --> 00:17:45,800
This indicates that they are actively eating there.
375
00:17:47,800 --> 00:17:50,730
In the case of individuals,
376
00:17:50,730 --> 00:17:53,130
that were about to migrate,
377
00:17:53,130 --> 00:17:55,130
we see that those stomachs were full,
378
00:17:55,130 --> 00:17:56,800
but most of them
379
00:17:56,800 --> 00:17:58,800
was full of prey
380
00:17:58,800 --> 00:18:00,800
in a high state of digestion.
381
00:18:00,800 --> 00:18:02,800
So much so that in theLobianchia dofleini
382
00:18:02,800 --> 00:18:04,990
so digested that we were unable to quantify copepods.
383
00:18:04,990 --> 00:18:06,990
There was a digested mass
384
00:18:06,990 --> 00:18:08,990
which could not be quantified, and therefore
385
00:18:08,990 --> 00:18:10,990
the digestion scale methodology
386
00:18:10,990 --> 00:18:12,790
has not been efficient with this species.
387
00:18:12,790 --> 00:18:15,090
For the future we will consider using
388
00:18:15,090 --> 00:18:17,490
imaging techniques to
389
00:18:17,490 --> 00:18:20,170
quantify the area of this digested mass.
390
00:18:20,170 --> 00:18:22,770
But in any case, the results suggest
391
00:18:22,770 --> 00:18:24,770
that if there are no fresh prey,
392
00:18:24,770 --> 00:18:26,770
evidently they do not eat during
393
00:18:26,770 --> 00:18:28,770
the day in the mesopelagic layer.
394
00:18:28,770 --> 00:18:31,040
However, the question we asked ourselves,
395
00:18:31,040 --> 00:18:32,570
what worried us most was,
396
00:18:32,570 --> 00:18:35,020
why stomachs are full and very digested
397
00:18:35,020 --> 00:18:38,020
just before the next migration.
398
00:18:38,020 --> 00:18:41,020
The most plausible explanation for us
399
00:18:41,020 --> 00:18:43,020
is that these contents come from
400
00:18:43,020 --> 00:18:45,020
the last migration they carried out.
401
00:18:45,020 --> 00:18:47,020
We do not know when this last migration took place,
402
00:18:47,020 --> 00:18:49,820
whether it was 1, 2 or 3 nights before is impossible to know,
403
00:18:49,820 --> 00:18:52,160
but we know that this implies that the system
404
00:18:52,160 --> 00:18:54,560
digestive and evacuation processes are very slow.
405
00:18:54,560 --> 00:18:56,970
And something that I think deserves more research,
406
00:18:56,970 --> 00:18:58,970
because it has implications on the
407
00:18:58,970 --> 00:19:00,470
active flux issue.
408
00:19:00,770 --> 00:19:02,470
This is in line with the theory of
409
00:19:02,470 --> 00:19:04,470
Sutton and Hopkins, which says that
410
00:19:04,470 --> 00:19:06,470
the migrant population is divided into
411
00:19:06,470 --> 00:19:08,470
migrants that feed at night,
412
00:19:08,470 --> 00:19:10,470
and individuals that choose not to migrate
413
00:19:10,470 --> 00:19:12,770
because they are in a post-nesting state.
414
00:19:12,770 --> 00:19:14,770
It also fits with the hypothesis
415
00:19:14,770 --> 00:19:16,970
of Pearre, which states that not all individuals
416
00:19:16,970 --> 00:19:19,770
migrate, only those that feel hungry go up.
417
00:19:19,770 --> 00:19:21,770
They don't all go down at the same time, if not
418
00:19:21,770 --> 00:19:24,770
asynchronously as they are satiated.
419
00:19:25,770 --> 00:19:28,070
These are the results of the diet, in which
420
00:19:28,070 --> 00:19:30,070
mainly it is seen that the food
421
00:19:30,070 --> 00:19:32,070
are copepods, followed by amphipods,
422
00:19:32,070 --> 00:19:33,130
and euphausiaceans.
423
00:19:33,130 --> 00:19:35,130
and the Lobianchia dofleini,
424
00:19:35,130 --> 00:19:38,030
eats copepods and euphausiids interchangeably,
425
00:19:38,030 --> 00:19:40,730
and also some ostracods in smaller quantities.
426
00:19:41,990 --> 00:19:44,730
The daily rations we saw that
427
00:19:44,730 --> 00:19:47,230
2% of the body weight of the Hygophum hygomi
428
00:19:47,230 --> 00:19:49,630
is what it eats per day;
429
00:19:49,630 --> 00:19:52,030
and theLobianchia dofleini is 1.34.
430
00:19:52,030 --> 00:19:54,330
This is close to the values
431
00:19:54,330 --> 00:19:56,330
that Pusch obtained in the same area,
432
00:19:56,330 --> 00:19:59,330
here near the Canary Islands for the same species.
433
00:20:01,030 --> 00:20:05,030
What implications does this have for the active flux?
434
00:20:05,030 --> 00:20:07,830
What I said was the important thing about the job.
435
00:20:07,830 --> 00:20:10,530
The results suggest that these myctophids
436
00:20:10,530 --> 00:20:12,630
return to the deep reflection layer,
437
00:20:12,630 --> 00:20:14,630
just after they feel satiated.
438
00:20:14,630 --> 00:20:16,630
When they fill their stomachs they go down.
439
00:20:16,630 --> 00:20:19,630
Moreover, they seem to spend a lot of time digesting.
440
00:20:19,990 --> 00:20:22,630
This implies high efficiency in the
441
00:20:22,630 --> 00:20:25,630
export of carbon to deeper waters.
442
00:20:25,630 --> 00:20:27,630
Moreover, if we consider that this family
443
00:20:27,630 --> 00:20:29,630
constitutes 70% of this migrant mass
444
00:20:29,630 --> 00:20:31,630
and mesopelagic mass,
445
00:20:31,630 --> 00:20:33,630
we can assume that myctophids
446
00:20:33,630 --> 00:20:35,630
probably represent a part of the
447
00:20:35,630 --> 00:20:37,630
very important of the active flux.
448
00:20:38,630 --> 00:20:40,630
Only as an approximation,
449
00:20:40,630 --> 00:20:42,630
to put some values,
450
00:20:42,990 --> 00:20:46,150
using a migrant biomass value,
451
00:20:46,150 --> 00:20:48,150
in terms of carbon,
452
00:20:48,950 --> 00:20:51,150
calculated by experts
453
00:20:51,150 --> 00:20:53,150
in the Canary Islands area,
454
00:20:53,150 --> 00:20:55,850
obtained a very conservative value
455
00:20:55,850 --> 00:20:58,740
of migrant biomass of 158.2 millimoles
456
00:20:58,740 --> 00:21:00,740
carbon dioxide emissions per square metre per day.
457
00:21:00,940 --> 00:21:04,040
If we correct this with the fact that 70% of biomass
458
00:21:04,040 --> 00:21:06,040
are myctophids, and that
459
00:21:06,040 --> 00:21:09,440
ingest 1.76% of their body weight.
460
00:21:09,440 --> 00:21:11,440
It is a value we have obtained from the
461
00:21:11,440 --> 00:21:13,970
value I have shown above.
462
00:21:14,570 --> 00:21:17,370
We obtain that only myctophids and only
463
00:21:17,370 --> 00:21:20,240
considering the active flux of the digestive tract,
464
00:21:20,240 --> 00:21:25,240
are exporting 1.83 millimores of carbon
465
00:21:25,240 --> 00:21:26,740
square metre per day.
466
00:21:26,740 --> 00:21:29,120
I do not know you can imagine whether it is too much or too little,
467
00:21:29,120 --> 00:21:31,220
I have put some values around here to see
468
00:21:31,220 --> 00:21:35,220
what is the importance of this value.
469
00:21:35,220 --> 00:21:37,420
If we compare it with what they are exporting
470
00:21:37,420 --> 00:21:40,120
migrators, only the zooplankton part,
471
00:21:41,520 --> 00:21:44,120
in the Canary Islands is 0.33 and
472
00:21:44,120 --> 00:21:46,120
in Bermuda is 0.17.
473
00:21:47,000 --> 00:21:49,320
Micronekton values are much higher,
474
00:21:49,320 --> 00:21:51,820
and yet it is studied more for active flux.
475
00:21:53,820 --> 00:21:56,370
Considering micronekton values,
476
00:21:56,370 --> 00:21:58,370
the same community I work with, but
477
00:21:58,370 --> 00:22:01,470
derived from the consumption of zooplankton.
478
00:22:01,970 --> 00:22:04,470
Hernández-León in 2010 argued that
479
00:22:04,470 --> 00:22:06,470
the Canary Islands, in a scenario
480
00:22:06,470 --> 00:22:08,970
not very productive, had values between
481
00:22:08,970 --> 00:22:12,470
1.6 and 2.8, close to the value I get,
482
00:22:12,470 --> 00:22:14,470
that seems to fit the 2 methodologies
483
00:22:14,470 --> 00:22:17,270
to estimate the active flux.
484
00:22:17,270 --> 00:22:19,270
And in a bloom scenario, of course
485
00:22:19,270 --> 00:22:21,270
exceed these values.
486
00:22:22,270 --> 00:22:24,270
And well compared to the other one
487
00:22:24,270 --> 00:22:26,670
great mechanism of the biological pump that
488
00:22:26,670 --> 00:22:28,670
is the gravitational flux.
489
00:22:28,670 --> 00:22:31,480
In the Canary Islands, work by Neuer,
490
00:22:31,480 --> 00:22:33,480
values were obtained for both a scenario
491
00:22:33,480 --> 00:22:35,880
very productive and unproductive,
492
00:22:35,880 --> 00:22:37,880
had lower values than ours.
493
00:22:37,990 --> 00:22:41,880
There is also as yet unpublished data from
494
00:22:41,880 --> 00:22:44,100
Hernández-León in the Canary current,
495
00:22:44,100 --> 00:22:45,900
above the archipelago.
496
00:22:45,900 --> 00:22:49,670
The values they hold are also lower than ours.
497
00:22:49,670 --> 00:22:51,670
If we look at the values of
498
00:22:51,670 --> 00:22:53,670
Alonso González et al,
499
00:22:53,670 --> 00:22:55,670
this time in the south of the Canary Islands,
500
00:22:55,670 --> 00:22:57,670
the Canary Current, but to the south.
501
00:22:57,970 --> 00:23:02,670
We see that an area not affected by eddies,
502
00:23:02,670 --> 00:23:04,670
has a value of 5.8, which is quite a lot
503
00:23:04,670 --> 00:23:06,870
than our own, and even if we consider
504
00:23:06,870 --> 00:23:09,130
eddy zones that are enriched
505
00:23:09,130 --> 00:23:11,130
and bloom stage, these values are
506
00:23:11,130 --> 00:23:13,630
obviously bigger than the ones we got.
507
00:23:13,630 --> 00:23:16,040
And in the case of Bermuda and Hawaii,
508
00:23:16,040 --> 00:23:21,240
what I wanted to show is that to begin with
509
00:23:21,240 --> 00:23:24,000
these estimates vary widely.
510
00:23:24,000 --> 00:23:26,400
It is evident, because there is a strong spatio-temporal
511
00:23:26,400 --> 00:23:28,750
variety and depends on the methodology
512
00:23:28,750 --> 00:23:29,650
that has been used.
513
00:23:29,650 --> 00:23:31,650
In some cases our values are higher,
514
00:23:31,650 --> 00:23:32,650
in other lower.
515
00:23:32,650 --> 00:23:35,150
The important thing is that they are in the same order of magnitude
516
00:23:35,150 --> 00:23:37,650
and they are also higher than the estimates.
517
00:23:37,950 --> 00:23:40,850
All this suggests that this figure,
518
00:23:40,850 --> 00:23:42,850
we believe, it is important enough
519
00:23:42,850 --> 00:23:46,350
to begin to consider
520
00:23:46,350 --> 00:23:49,350
to start conducting specific studies
521
00:23:49,350 --> 00:23:51,850
for the estimation of the active flux of the micronekton.
522
00:23:53,850 --> 00:23:57,050
To sum up come the conclusions,
523
00:23:57,050 --> 00:23:59,550
is that the species of Hygophum hygomi and
524
00:23:59,550 --> 00:24:01,930
Lobianchia dofleini, the epipelagic abundance
525
00:24:01,930 --> 00:24:03,750
during a 24-hour cycle,
526
00:24:03,750 --> 00:24:05,750
showed that they perform vertical migrations
527
00:24:05,750 --> 00:24:07,750
normal at dusk, and that
528
00:24:07,750 --> 00:24:09,950
its presence, well above the pycnocline,
529
00:24:09,950 --> 00:24:12,950
is showing that this migration is inter-zonal.
530
00:24:12,950 --> 00:24:15,950
The decline, in particular of the Lobianchia dofleini,
531
00:24:15,950 --> 00:24:17,950
and the abundance in the epipelagic layer
532
00:24:17,950 --> 00:24:19,950
overnight, together with
533
00:24:19,950 --> 00:24:22,350
their subsequent presence in the mesopelagic layer,
534
00:24:22,350 --> 00:24:26,350
suggests that they are doing midnight sinking
535
00:24:26,350 --> 00:24:28,350
after filling their stomachs.
536
00:24:28,350 --> 00:24:31,350
And the predominance of fresh prey
537
00:24:31,350 --> 00:24:33,350
in both species at night
538
00:24:33,350 --> 00:24:35,350
in the epipelagic layer, showed
539
00:24:35,350 --> 00:24:38,350
night-time feeding in surface waters.
540
00:24:39,750 --> 00:24:41,950
Both species showed that their stomachs
541
00:24:41,950 --> 00:24:43,950
were full and well-digested, just before
542
00:24:43,950 --> 00:24:46,150
the following migration, suggesting
543
00:24:46,150 --> 00:24:48,150
that part of the population is not migrating
544
00:24:48,150 --> 00:24:50,150
and that it is in a state of post-digestion,
545
00:24:50,150 --> 00:24:52,150
and this implies a very slow evacuation system.
546
00:24:52,150 --> 00:24:54,150
Much slower than
547
00:24:54,150 --> 00:24:57,150
the time it takes for them to return to the deep reflection layer.
548
00:24:57,150 --> 00:24:59,150
In addition, they mainly eat
549
00:24:59,150 --> 00:25:02,650
copepods, euphausiids and daily allowances
550
00:25:02,650 --> 00:25:06,650
were 2% and 1.34% of body weight.
551
00:25:06,650 --> 00:25:08,650
To summarise,
552
00:25:08,650 --> 00:25:10,650
that are vertical inter-zonal
553
00:25:10,650 --> 00:25:13,330
migrants, that migration is inter-zonal,
554
00:25:13,330 --> 00:25:15,330
that feeding should be at night in
555
00:25:15,330 --> 00:25:17,330
surface waters; which are
556
00:25:17,330 --> 00:25:19,330
dropping immediately after
557
00:25:19,330 --> 00:25:21,860
ingesting the food and that the digestive system
558
00:25:21,860 --> 00:25:23,560
is extremely slow.
559
00:25:23,560 --> 00:25:25,880
These are all appropriate conditions
560
00:25:25,880 --> 00:25:27,880
to think that myctophids are
561
00:25:27,880 --> 00:25:30,770
exporting carbon to deeper layers
562
00:25:30,770 --> 00:25:32,770
and that they should play an important role in the
563
00:25:32,770 --> 00:25:34,770
in the biological carbon pump.
564
00:25:35,350 --> 00:25:38,970
Simply put, what we want to say
565
00:25:38,970 --> 00:25:41,970
is that we would like to recommend that in the
566
00:25:41,970 --> 00:25:43,970
future active flux works,
567
00:25:43,970 --> 00:25:45,970
his possibility should begin to be considered,
568
00:25:45,970 --> 00:25:47,970
the micronekton is being considered,
569
00:25:47,970 --> 00:25:50,520
which is still unknown in this field of work.
570
00:25:50,520 --> 00:25:52,520
And I would like to thank all the
571
00:25:52,520 --> 00:25:54,520
people who have helped me,
572
00:25:54,520 --> 00:25:58,520
to the Faculty of Marine Sciences where I am doing my thesis,
573
00:25:58,520 --> 00:26:02,520
the University of La Laguna, where I started my first digestion work,
574
00:26:02,820 --> 00:26:05,520
Instituto Canario de Ciencias Marinas, in particular
575
00:26:05,520 --> 00:26:07,520
Fernando Bordes for teaching me
576
00:26:07,520 --> 00:26:09,520
everything about acoustics,
577
00:26:11,520 --> 00:26:13,520
and the Minister of Science and Innovation.
578
00:26:13,520 --> 00:26:17,520
And thanks to all my colleagues for
579
00:26:17,520 --> 00:26:19,520
all moments on board, in the laboratory,
580
00:26:19,520 --> 00:26:23,520
and for the time away from work that helps.
581
00:26:23,520 --> 00:26:24,520
Thank you.
582
00:26:24,520 --> 00:26:26,520
If you have any questions.
583
00:26:28,520 --> 00:26:30,520
Please do not worry, because I do not expect you to
584
00:26:30,520 --> 00:26:32,520
to be specialised in this.
585
00:26:32,520 --> 00:26:34,520
And those questions that begin with
586
00:26:34,520 --> 00:26:36,520
"this is probably nonsense".
587
00:26:36,520 --> 00:26:39,520
are probably the best questions.
588
00:26:41,520 --> 00:26:49,520
How do they know that those who migrate do not have
589
00:26:49,520 --> 00:26:56,520
the digestive tract full and able to
590
00:26:56,520 --> 00:27:02,520
leave the waste on the surface, in that superior
591
00:27:02,520 --> 00:27:04,220
layer?
592
00:27:04,220 --> 00:27:06,220
I do not know, maybe I did not understand.
593
00:27:06,220 --> 00:27:08,220
You may say that only those who have
594
00:27:08,220 --> 00:27:11,220
empty stomach.
595
00:27:12,720 --> 00:27:15,220
When we see them feeding on the surface,
596
00:27:15,220 --> 00:27:19,720
we find all kinds of stomachs, from empty stomachs
597
00:27:19,720 --> 00:27:20,370
to full stomachs.
598
00:27:20,370 --> 00:27:22,370
I guess it depends on the individual success that
599
00:27:22,370 --> 00:27:24,370
have each finding food,
600
00:27:24,870 --> 00:27:27,510
but the material is fresh.
601
00:27:27,510 --> 00:27:34,510
It did not have time to be digested and so they did not evacuate.
602
00:27:34,510 --> 00:27:38,440
There is a minority, a residue of digested material
603
00:27:38,440 --> 00:27:41,340
much smaller than all that fresh mass.
604
00:27:41,840 --> 00:27:44,840
Then most of the well-digested preys
605
00:27:44,840 --> 00:27:46,840
are below.
606
00:27:46,840 --> 00:27:48,840
So we think that not everything
607
00:27:48,840 --> 00:27:50,840
but most of what they eat
608
00:27:50,840 --> 00:27:53,240
it takes so long to digest that it already
609
00:27:53,240 --> 00:27:56,240
when they go to evacuate are in the deep reflection layer.
610
00:27:58,240 --> 00:28:00,240
Yes, it is just that I got stuck
611
00:28:00,240 --> 00:28:02,240
because it takes so long, it takes so long, so
612
00:28:02,240 --> 00:28:04,550
I did not remember you saying that
613
00:28:04,550 --> 00:28:06,550
up there it was totally fresh what was
614
00:28:06,550 --> 00:28:08,550
in the stomach.
615
00:28:08,550 --> 00:28:10,550
If it takes that long to digest,
616
00:28:10,550 --> 00:28:12,550
between rising again,
617
00:28:12,550 --> 00:28:15,100
he still has a full stomach.
618
00:28:15,100 --> 00:28:19,500
Yes yes, but you haven't found that.
619
00:28:19,500 --> 00:28:21,830
You have only found if it was full
620
00:28:21,830 --> 00:28:23,830
was about fresh things.
621
00:28:23,830 --> 00:28:25,830
Yes, almost everything,
622
00:28:25,830 --> 00:28:27,830
there is a tiny percentage.
623
00:28:33,830 --> 00:28:35,830
Any further questions?
624
00:28:41,830 --> 00:28:43,830
Do you consider
625
00:28:43,830 --> 00:28:46,830
that in the value you give us? The 1.83.
626
00:28:52,830 --> 00:28:56,830
This is still an approximation.
627
00:28:56,830 --> 00:28:58,830
I understand and say that the majority
628
00:28:58,830 --> 00:29:01,830
ingested goes to the mesopelagic layer.
629
00:29:01,830 --> 00:29:06,830
We do not know the exact percentage.
630
00:29:06,830 --> 00:29:09,330
This value is derived from the weight of
631
00:29:09,330 --> 00:29:12,330
the contents at the maximum filling stage.
632
00:29:12,330 --> 00:29:14,330
And as everything is fresh on the surface
633
00:29:14,330 --> 00:29:16,330
and I only find myself digested
634
00:29:16,330 --> 00:29:18,830
down there, I believe that most of them
635
00:29:18,830 --> 00:29:20,830
removing a negligible part,
636
00:29:20,830 --> 00:29:23,330
maybe there is something evacuated on the surface,
637
00:29:24,230 --> 00:29:26,830
but I consider it negligible because of the quantity
638
00:29:26,830 --> 00:29:28,830
very small amount of digested material
639
00:29:28,830 --> 00:29:30,830
when they are on the surface.
640
00:29:30,990 --> 00:29:34,830
A small correction should be applied.
641
00:29:36,830 --> 00:29:38,830
But we do not know which one.
642
00:29:40,830 --> 00:29:42,830
It is an approximation, this
643
00:29:42,830 --> 00:29:44,830
is not a job that has been
644
00:29:44,830 --> 00:29:46,830
que desde el diseño muestral
645
00:29:48,240 --> 00:29:50,830
that the experiment was conducted to calculate
646
00:29:50,830 --> 00:29:52,030
the active flux.
647
00:29:52,030 --> 00:29:55,230
It is a by-product obtained from
648
00:29:55,230 --> 00:29:57,230
other work that was carried out,
649
00:29:57,230 --> 00:29:59,230
approximation
650
00:29:59,230 --> 00:30:01,730
I am well aware that the value that
651
00:30:01,730 --> 00:30:03,730
well...
652
00:30:04,730 --> 00:30:07,730
You have to go deeper, just see that value is important.
653
00:30:07,730 --> 00:30:09,730
It is important and
654
00:30:09,730 --> 00:30:11,730
This needs to be explored further.
655
00:30:15,030 --> 00:30:17,730
When you have the data that
656
00:30:17,730 --> 00:30:19,730
of the museums
657
00:30:19,730 --> 00:30:21,330
that are arriving now.
658
00:30:21,330 --> 00:30:24,330
Your idea is to build a kind of time series
659
00:30:24,330 --> 00:30:27,330
whether they nest more or eat more,
660
00:30:27,330 --> 00:30:30,830
if more individuals go up for a period?
661
00:30:34,830 --> 00:30:37,130
If you will allow me the samples that are there,
662
00:30:37,130 --> 00:30:40,130
we want to see if there are areas
663
00:30:40,130 --> 00:30:43,130
where there were periods of more or less production,
664
00:30:43,130 --> 00:30:45,130
but I am not so sure we have
665
00:30:45,130 --> 00:30:47,630
that we have that kind of sampling.
666
00:30:47,630 --> 00:30:51,630
The Fuerteventura scenario may then be restricted.
667
00:30:53,630 --> 00:30:55,630
We do not know in what,
668
00:30:55,630 --> 00:30:57,630
well we know what time of year it was.
669
00:30:57,630 --> 00:31:01,630
I mean, we do not know if we have enough
670
00:31:01,630 --> 00:31:04,630
samples to make a series of the year,
671
00:31:04,630 --> 00:31:06,630
We don't know if we have enough variety
672
00:31:06,630 --> 00:31:08,630
of bloom or non-bloom scene.
673
00:31:08,630 --> 00:31:10,630
We have to look at when all this comes in.
674
00:31:10,630 --> 00:31:13,130
But in first instance only the area of Fuerteventura.
675
00:31:17,130 --> 00:31:20,130
I think it is quite a productive area.
676
00:31:20,830 --> 00:31:24,820
We have to do work on that.
677
00:31:24,820 --> 00:31:26,820
I guess they are profiled
678
00:31:26,820 --> 00:31:30,820
CTD, chlorophylls and we can see
679
00:31:30,820 --> 00:31:33,520
whether they were in a bloom stage or not.
680
00:31:33,520 --> 00:31:36,020
We were already thinking about it.
681
00:31:40,020 --> 00:31:42,020
Any students?