Seaweed biomass along the depth gradient in 2021:
In 2021, a total of 21 biomass dominant macroalgal taxa (11
Phaeophyceae, 6 Rhodophyta, 4 Chlorophyta) were collected along the
depth transect. In contrast to the previous studies, six macroalgal taxa
were not biomass relevant anymore as they were either absent
(Phaeophyceae: Chorda filum , Haplospora globosa ,Laminaria solidungula ; Rhodophyta: Cystoclonium purpureum ,Odonthalia dentata ) or were only encountered in negligible
amounts of <0.1g FW (Phaeophyceae: Battersia arctica ).
Detailed FW and DW data of single species and sums of groups in 2021 are
given in Appendix 3 and Appendix 4, respectively.
In the infralittoral zone (0m) the macroalgal community was most diverse
with 15 taxa present and understory seaweed FW (2.2 kg FW
m-²), ‘Other Phaeophyceae’ (1.2 kg FW
m-²) as well as Rhodophyta (0.9 kg FW
m-²) exhibited their maximum biomass. In contrast, the
biomass peak of overall seaweed FW (11.5 kg FW m-²)
and kelp FW (11.3 kg FW m-²) was at 2.5m. At 5 and 10m
the kelp species A. esculenta (3.6 and 0.9 kg FW
m-², respectively) showed the highest biomass of all
seaweeds. Because of the high A. esculenta FW, kelps were
responsible for 95 and 56% of the overall seaweed FW at 5 and 10m,
respectively. At 15 m the ground was almost exclusively covered with
Rhodophyta (0.335 kg FW m-²) and dominated byPhycodrys rubens (0.317 kg FW m-²), whileA. esculenta (0.0009 kg FW m-²) was near to its
lower distribution limit.