Annual change in population of Jorunna rubescens ( Bergh, 1876 )


by Philibert Bidgrain

Site Location : Lagon de l'hermitage, "La closerie du lagon"


I made each month in the late afternoon 2-3 counts on the same area of the lagoon .

This table presents the results of population monitoring. For each month, I indicated the minimum and maximum number of specimens observed ( sp ), and the number of spawns ( S ) and mating events ( M )

The purpose of this count is to show how this population evolves according to the season in several years ...

 
Janv
Feb
March
April
May
June
Jully
Aug
Sept
Oct
Nov
Dec
2010
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
min
 
 
 
 
 
 
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
3
0
0
3
0
0
0
0
max
 
 
 
 
 
 
0
0
0
1
0
0
1
0
0
1
1
0
1
1
0
0
0
0
2
0
1
4
6
0
3
5
0
1
0
0
2011
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
Sp
S
M
min
0
0
0
max
3
1
0