Role of a Paramuricea clavata ftidifithforest in modifying the coralligenous assemblages
Alice Scinto1, Marco Bertolino2, Barbara Calcinai2, Carla Huete-Stauffer1, Monica Previati1, Tiziana Romagnoli2, Carlo Cerrano1 Introduction
Habitat complexity and Biodiversity In the Mediterranean Sea the environments hosting the higher biodiversity are the Posidonia oceanica meadows and the coralligenous accretions. Introduction
Posidonia oceanica meadows can be centuries-old
The significantly lower depositional rates within the plant canopy compared to the unvegetated floor are probably attributable to the reduced turbulence inside the canopy, which buffers resuspension. Comparative data from a P. oceanica meadows aadnd a near by unvegetated aaearea inddcateicate ttathat ttehe presence of this seagrass reduced near-bottom turbulence by 2-5 folds
From Garcia and Duarte, 2001 Introduction
Coralli genous accretions grow ing a t about 0.1 mm/year, can be thousands of years old.
Contrary to P. oceanica meadows, the real ecological importance of coralligenous is still underestimated
From Ballesteros, 2006 Introduction
In the last ten years (in particular during the summer 1999 and 2003) extended mass mortality events have affected the benthic populations in many areas around the northwest Mediterranean, affecting mainly suspension feeders
But what happens when Paramuricea clavata colilonies di dide and disappear?
(Cerrano et al, 2000; Perez et al. 2000; Ribes and Coma 2005; Garrabou et al in press). Aims
Here we evaluated how P. clavata can affect its surrounding ambient and if there are species facilitated by its presence.
The effects of its regression are hypothesized Materials and methods
Experimental work
To evaluate a possible role of P. clavata in affecting the presence of other species, at 40 m depth, four different approaches were followed : 1) Analysis, in two sites, of the diversity in term of species presence/absence by pppghotosampling of standard areas (15x20 cm2) outside (30 pp)hotos) and inside (30 photos) a gorgonian forest 2) Positioning of six plastic panels both outside and inside a gorgonian forest to evidence eventual effects of sea fans on the dynamics of colonization of a substratum for a period of 4 months
3))y Evaluation of the entity of flows outside and inside a gggorgonian forest ( 11 ± 0.37 col/m2) by plaster balls (Muus, 1968)
4))p Comparison between sediment granulometries Materials and methods
The study sites Punta del Faro Marine Protected Area of Portofino
S. Stefano shoal Materials and methods
1) PHOTOSAMPLING
The considered categories
Sediment Algal mat Corallinaceous Algae Bushy Algae Boring Sponges Encructing Sponges Massive Sponges Parazoanthus axinellae Leptopsammia pruvoti Upright Bryozoa Encructing Bryozoa Outside gorgonian forest Results 1)
PtfiPortofino
50 45 40 35 30 of species of yy 25 20 15
% frequenc % 10 5 0 ryozoa ryozoa inellae psammia ral Algae hy Algae zoanthus ncrusting Sediment mat Algal ncrusting Sponge e Sponge ruvoti g Sponge Bryozoa BB xx oo oo tt ss aa vv pp EE EE a C Bu Par Lept Borin Massi Uprigh
out in
Into the gorgonian forest the cover of sediment is 5% more abundant then outside Results 1)
PtfiPortofino
50 45 40 35 30 of species of yy 25 20 15
% frequenc % 10 5 0 ryozoa ryozoa inellae psammia ral Algae hy Algae zoanthus ncrusting Sediment mat Algal ncrusting Sponge e Sponge ruvoti g Sponge Bryozoa BB xx oo oo tt ss aa vv pp EE EE a C Bu Par Lept Borin Massi Uprigh
out in
The algal fraction outside the gorgonian forest is composed mainly by algal mat (41.7%) and bushy algae (24.5%) and by corallinaceous algae (32.7%) inside Results 1)
Portofino 14
12
10
8
6
4
2
0 us a ge ht ing ing e ive ge oa mia ng tt tt hh oo nn ee gg gg ss nn Bori Spo Spo Upri Mas Bryoz Spon Bryoz pruvoti Encrus Encrus axinella Parazoant Leptopsam
OUT IN
Considering exclusively the animal fraction, Parazoanthus axinellae (1.98%)isthe most frequent outside the gorgonian forest, while inside encrusting sponges (9.48%), massive sponges (3.22%), Leptosammia pruvoti (1.46%) and upright bryozoans (0.87%) are more abundant Results 1)
S.Stefano
40 35 ss 30 25 y of specie y of
cc 20 15 10 % frequen 5 0 Sediment mat Algal Bryozoa Bryozoa xinellae oral Algae t Bryozoa shy Algae azoanthus ve Sponge topsammia pruvoti ng Sponge Encrusting ng Sponge ng ii ii rr aa hh uu CC pp B Pa Le Bori Mass Uprig Encrust
out in
Inside the gorgonian forest the cover of sediment is similar to outside Results 1)
S.Stefano
40 35 ss 30 25 y of specie y of
cc 20 15 10 % frequen 5 0 Sediment mat Algal Bryozoa Bryozoa xinellae oral Algae t Bryozoa shy Algae azoanthus ve Sponge topsammia pruvoti ng Sponge Encrusting ng Sponge ng ii ii rr aa hh uu CC pp B Pa Le Bori Mass Uprig Encrust
out in
The algal fraction outside the gorgonian forest is composed mainly by algal mat (()y25.3%) and by corallinaceous al g()gae (28.3%) inside Results 1)
S.Stefano
14
12
10
8
6
4
2
0 Sponge Bryozoa Bryozoa Encrusting Encrusting pruvoti axinellae oring Sponge ssive Sponge right Bryozoa Parazoanthus Leptopsammia BB aa pp M U
OUT IN
In S. Stefano Parazoanthus axinellae ( 3.97%) and encrusting Bryozoa (4.17%) are the dominant animal fraction outside the gorgonian forest, while inside the gorgonian forest encrusting sponge (10.43%), massive sponge (1.68%), Leptosammia pruvoti (1.73%) and upright bryozoans (9.84%) are more abundant Materials and methods
2) PANELS
2) PitiiPositioning of sixpltilastic panels outidtside and iidinside a gorgonian forest to evidence eventual effects of sea fans on the dynamics of colonization of a substratum for a period of 4 months (May-September 2008)
INSIDE OUTSIDE Results 2)
50 45 40 ies 35 30 25 ncy of spec of ncy 20 15
% freque 10 5 0 Corallinaceous Green algae Spirorbids Other serpulids Bryozoa algae
OUT IN
After 4 months outside gorgonians, green algae and serpulids represent the 38% and 10.5% resppyectively inside gorgonians, corallinaceous algae and bryozoans represent the 44.5% 25.6% respectively Results 2)
10 9 8 7 6 5 4 3 2 1 0 hiella nia orella pida opora sp. ia ea avella lium arella ricosa lanica ris solem cc tt aa pp ss nn cc nn ee cc mm hi Be ob Es Dis ven linea Diplo magel Liche Plagie sangui Schizo Schizobra
OUT IN
Shannon diversity index 3 2952,95 2,9 2,85 Shannon diversity index 2,8 2,75 underlines a major diversity 2,7 2,65 in species inside the 2,6 2,55 gorgonian forests 2,5
OUT IN Materials and methods
3) PLASTER BALLS
The entity of the current outside and inside a gorgonian forest (11 ± 0,37 col/m2) by plaster balls (Muus, 1968) was evaluated at three different levels:
At the top
In the center
At the base Results 3)
25
Water speed equivalents 20
15
ls dissolution OUT ll IN
10 V=3,65*(DF-1) (cm/sec) % plasterba
5
0 BASE CENTER TOP BASE 31,8109 Out gorgonian forest % of plaster ball dissolution OUT CENTER 33,63693 Is :17.5% at the base,12.4% in the center 6.2% at the top TOP 36,351 BASE 29,40307 Among gorgonian colonies, water movement IN CENTER 32,05264 decreased of 5.72% during calm sea period TOP 34,5112 Materials and methods
4) SEDIMENTS
The sediment was collected in the crevices of coralligenous outside and inside the sea fans with a spatula Sediment were divided into 3 size classes using a nested series of sieves (meshes <500 µm, 500 µm < 1mm, 1mm ) and weighted Results 4)
100 Sediment 90 80 70 60 50 40 30 20 10 0 < 500µm >500µm <1 mm >1 mm
OUT IN
Sediment fine fraction (<500 µm) was more abundant in gorgonians forest, coarse ftifraction (> 1mm) prevaile d out a gorgonians ftforest,while the itinterme ditdiate ftifraction (> 500 µm < 1mm) shows only little differences between out and in Discussion IN OUT
Healthy population: Damaged population:
- low current - water turbolence - fine sediment trapping - sediment resuspension - bottom stabilization - sediment run off - growth of corallinae algae - organic matter dilavation - high diversity - growth of green algae - low diversity Discussion IN OUT
Paramuricea clavata
Boring Massive Corallinaceous sponge sponge algae Leptosammia Encrustin pruvoti Upright g Bryozoa sponge
Bushy Algae
Encrusting Parazoanthus axinellae Bryozoa
Algal mat Conclusion
• Inside gorgonian forests several organisms can find an habitat characterized by peculiar physico-chemical features, a sort of “buffered zone” where modifications may occur slower respect to the surrounding ambient.
• Data here reported allowed to consider this species a true ecosystem engineer, able to affect local diversity and biomass.
• Gorgonian forest may have a great importance in the coralligenous dynamics not only affecting the community structure but also creating, at the tested depth, the optimal conditions for the development of coralline algae, the main builders of these bioconst ruc tions.
• These results ltlet us hig hlight the itimportance to promoterapid and effecti ve measures of protection of coralligenous assemblages to avoid future activities of restoration as a consequence of their loss