Figure 1
Fish samples
Table 1
Stomach contents in Syngnathus abaster
| Prey items | F% | N% | W% | IRI% |
|---|---|---|---|---|
| Copepods | ||||
| Calanipeda aquaedulcis | 51.06 | 64.71 | 1.26 | 10.99 |
| Other cyclopoids | 4.26 | 1.76 | 0.20 | 0.03 |
| Ostracods | 10.64 | 0.79 | 0.16 | 0.03 |
| Amphipods | 68.09 | 18.44 | 0.81 | 4.28 |
| Amphipod pieces | 10.64 | 0.00 | 0.00 | 0.00 |
| Diptera | ||||
| Chironomidae larvae | 4.26 | 0.48 | 93.67 | 1.31 |
| Fish larvae (Syngnathus sp.) | 2.13 | 0.32 | 0.74 | 0.01 |
| Unknown eggs | 2.13 | 13.51 | 3.16 | 0.12 |
| Total prey number | 629 | |||
| Number of full stomachs | 52 | |||
[i] Note: F% – percentage frequency; N% – percentage of prey number; W% – percentage dry weight; IRI% – percentage relative importance index.
Table 2
Food composition in S. abaster size groups
| Prey items | Fish length groups | |||||
|---|---|---|---|---|---|---|
| < 60 mm | 60–100 mm | 100 mm > | ||||
| F% | IRI% | F% | IRI% | F% | IRI% | |
| Copepods | ||||||
| Calanipeda aquaedulcis | 0.00 | 0.00 | 56.10 | 0.49 | 7.37 | 28.99 |
| Other cyclopoids | 0.00 | 0.00 | 4.88 | 0.88 | 0.00 | 0.00 |
| Ostracods | 0.00 | 0.00 | 14.63 | 1.66 | 0.00 | 0.00 |
| Amphipods | 0.00 | 0.00 | 56.10 | 82.12 | 75.00 | 57.56 |
| Amphipod pieces | 0.00 | 0.00 | 36.59 | 0.00 | 0.00 | 0.00 |
| Diptera | ||||||
| Chironomidae larvae | 0.00 | 0.00 | 4.88 | 7.31 | 0.00 | 0.00 |
| Fish larvae (Syngnathus sp.) | 0.00 | 0.00 | 2.44 | 0.06 | 8.33 | 0.61 |
| Unknown eggs | 0.00 | 0.00 | 2.44 | 0.95 | 8.33 | 12.84 |
Figure 2
Relationship between the total length and the stomach fullness index in S. abaster
Table 3
Food composition in S.abaster stomachs in two seasons
| Prey items | Autumn | Spring | ||
|---|---|---|---|---|
| F% | IRI% | F% | IRI% | |
| Copepods | ||||
| Calanipeda aquaedulcis | 0.00 | 0.00 | 96.00 | 97.55 |
| Other cyclopoids | 6.67 | 3.22 | 0.00 | 0.00 |
| Ostracods | 16.67 | 3.63 | 0.00 | 0.00 |
| Amphipods | 53.33 | 76.81 | 64.00 | 2.17 |
| Amphipod pieces | 43.33 | 0.00 | 0.00 | 0.00 |
| Diptera | ||||
| Chironomidae larvae | 6.67 | 16.14 | 0.00 | 0.00 |
| Fish larvae (Syngnathus sp.) | 3.33 | 0.18 | 4.00 | 0.002 |
| Unknown eggs | 0.00 | 0.00 | 8.00 | 0.28 |
Table 4
Stomach contents in Syngnathus acus
| Prey items | F% | N% | W% | IRI % |
|---|---|---|---|---|
| Algae | ||||
| Diatom (Surirella sp.) | 1.54 | 0.15 | 0.00 | 0.004 |
| Brown algae pieces | 1.53 | 0.00 | 0.00 | 0.00 |
| Copepods | ||||
| Calanipeda aquaedulcis | 44.62 | 51.35 | 1.58 | 42.37 |
| Other Calanoids | 1.54 | 0.30 | 0.002 | 0.009 |
| Oithona sp. | 1.54 | 0.15 | 0.009 | 0.004 |
| Other cyclopoids | 10.77 | 3.61 | 0.64 | 0.82 |
| Harpacticoids | 1.54 | 0.15 | 0.0002 | 0.004 |
| Ostracods | 4.61 | 0.45 | 0.24 | 0.06 |
| Mysids | 1.54 | 0.15 | 0.09 | 0.007 |
| Amphipods | 66.15 | 42.62 | 2.90 | 54.04 |
| Amphipod pieces | 36.92 | 0.00 | 0.00 | 0.00 |
| Gastropods | 3.08 | 0.15 | 0.01 | 0.009 |
| Diptera | ||||
| Chironomidae larvae | 1.54 | 0.15 | 46.96 | 1.29 |
| Other Diptera larvae | 1.54 | 0.15 | 46.69 | 1.29 |
| Fish larvae (Syngnathus sp.) | 3.08 | 0.30 | 4.35 | 0.08 |
| Fish scales | 1.54 | 0.15 | 0.00 | 0.04 |
| Total prey number | 664 | |||
| Number of full stomachs | 65 | |||
Figure 3
Relationship between the total length and the stomach fullness index in S. acus
Table 5
Food composition in S. acus size groups
| Prey Items | Length groups | |||||
|---|---|---|---|---|---|---|
| < 60 mm | 60–100 mm | 100 mm > | ||||
| F% | IRI% | F% | IRI% | F% | IRI% | |
| Algae | ||||||
| Diatom (Surirella sp.) | 0.00 | 0.00 | 2.13 | 0.004 | 4.00 | 0.00 |
| Brown algae pieces | 0.00 | 0.00 | 0.00 | 0.00 | 4.00 | 0.00 |
| Copepods | ||||||
| Calanipeda aquaedulcis | 100.00 | 100.00 | 51.06 | 76.57 | 16.00 | 3.23 |
| Other Calanoids | 0.00 | 0.00 | 2.13 | 0.01 | 0.00 | 0.00 |
| Oithona sp. | 0.00 | 0.00 | 2.13 | 0.004 | 0.00 | 0.00 |
| Other Cyclopoids | 0.00 | 0.00 | 14.89 | 0.72 | 4.00 | 0.02 |
| Harpacticoids | 0.00 | 0.00 | 2.13 | 0.004 | 0.00 | 0.00 |
| Ostracods | 0.00 | 0.00 | 4.26 | 0.02 | 4.00 | 0.02 |
| Mysids | 0.00 | 0.00 | 0.00 | 0.00 | 4.00 | 0.02 |
| Amphipods | 0.00 | 0.00 | 59.57 | 22.47 | 60.00 | 96.65 |
| Amphipod pieces | 0.00 | 0.00 | 31.91 | 0.00 | 40.00 | 0.00 |
| Gastropods | 0.00 | 0.00 | 2.13 | 0.04 | 0.00 | 0.00 |
| Diptera | ||||||
| Chironomidae larvae | 0.00 | 0.00 | 0.00 | 0.00 | 4.00 | 0.03 |
| Other Diptera larvae | 0.00 | 0.00 | 2.13 | 0.18 | 0.00 | 0.00 |
| Fish larvae (Syngnathus sp.) | 0.00 | 0.00 | 2.13 | 0.01 | 4.00 | 0.02 |
| Fish scales | 0.00 | 0.00 | 2.13 | 0.004 | 0.00 | 0.00 |
Table 6
Prey groups consumed by S. acus during two seasons
| Prey items | Autumn | Spring | ||
|---|---|---|---|---|
| F% | IRI% | F% | IRI% | |
| Algae | ||||
| Diatom (Surirella sp.) | 3.13 | 0.22 | 0.00 | 0.00 |
| Brown algae pieces | 0.00 | 0.00 | 1.35 | 0.00 |
| Copepods | ||||
| Calanipeda aquaedulcis | 3.13 | 0.22 | 37.84 | 93.19 |
| Other calanoids | 3.13 | 0.44 | 0.00 | 0.00 |
| Oithona sp. | 3.13 | 0.23 | 0.00 | 0.00 |
| Other cyclopoids | 3.13 | 0.23 | 8.11 | 0.0002 |
| Harpacticoids | 0.00 | 0.00 | 1.35 | 0.0002 |
| Ostracods | 9.38 | 1.98 | 0.00 | 0.00 |
| Mysids | 3.13 | 0.22 | 0.00 | 0.00 |
| Amphipods | 50.00 | 85.18 | 36.49 | 6.75 |
| Amphipod pieces | 43.75 | 0.00 | 13.52 | 0.00 |
| Gastropods | 3.13 | 0.23 | 0.00 | 0.00 |
| Diptera | ||||
| Chironomidae larvae | 3.13 | 9.18 | 0.00 | 0.00 |
| Other Diptera larvae | 0.00 | 0.00 | 1.35 | 0.06 |
| Fish larvae (Syngnathus sp.) | 6.25 | 1.42 | 0.00 | 0.00 |
| Fish scales | 3.13 | 0.22 | 0.00 | 0.00 |
Figure 4
Relationships between the total length and the mouth width in pipefish species
Figure 5
Relationship between the total length and the total weight of ingested food in pipefish species