Effects of aquaculture on Mediterranean marine ecosystems

1. Effects of aquaculture on Mediterranean marine ecosystems I. Karakassis, D. Angel

2. Effects of aquaculture on marine biotic communities (modified after Milowski 2001)

3. Posidonia protects the seabed from errosion

4. Posidonia rhizomes Plagiotropic rhizome Orthotropic rhizome

5. Spp reproducing in P. oceanica meadows Lithignathus mormyrus Sparus auratus Oblada melanura Sapra sapra Paracentrotus lividus Symphodus roissali Antedon mediterraneus Murena helena Conger conger Lichia amia Seriola dumerili Mullus surmuletus Posidonia: provides shelter to juvenile fish and many manire invertebrates

6. Under anthropogenic pressure Posidonia meadows easily become degraded

7. … so that its past presence can only be detected by rhizomes left on the seabed

8. High turbidity in the water column is known to adversely affect Posidonia The reduced availability of light reduces the potential space for colonization by Posidonia to a more and more narrow coastal zone

9. During recent years it has been reported that Posidonia oceanica faces strong copetition by Caulepa taxifolia C. taxifolia is an alien species that recently invaded W. Mediterranean. It has no local grazers or other means to control its population and it excludes P. oceanica from coastal waters when established there

10. Mediterranean endemic (in need of protection under the Habitat Directive) a nursery ground for several species provides important services for coastal marine ecosystems (3D habitat for several invertebrate species) it stabilises the sandy beaches in the littoral zone under increasing pressure due to anthropogenic effects (pollution, trawling, harbour constructions etc) under increasing pressure due to nutrient enrichment of the coastal zones and flourish of fast growing macroalgae, e.g. Cladophora spp., Caulerpa sp. Why Posidonia is of vital importance

11. The habitat of P. oceanica (coarse sediment and strong currents) is “ideal” for fish farming since: it allows rapid dispersion of solute wastes minimal accumulation of particulates and excellent oxygenation of the water Posidonia meadows as fish farming sites

12. Posidonia is stressed at farming sites

13. reducing penetration or availability of light immediately under the cages (shadow effect) due to increased phytoplankton biomass due to increased suspended particulates by favouring the growth of epiphytes on Posidonia leaves competition with fast growing macroalgae accumulation of OM in the sediments increasing NH4 and H2S in the sediments However f/f causes adverse effects on Posidonia by:

14. Posidonia: primary production near and far from fish farms Reference station Changes in pp by an order of magnitude Farm sites Cancemi et al. (2003) Estuar coastal shelf Sci vol56

15. MedVeg sampling sites

16. MedVeg: sampling design MedVeg Report 2005, unpublished data

17. MedVeg fluxes measured with sediment traps Alicante Flux P=0.26*x-0.41 Sounion Flux P=0.10*x-0.59 MedVeg Report 2005, unpublished data

18. MedVeg Bioassays

19. MedVeg Bioassays * * * * * * * * * * * * * * Control site * signif different from control site MedVeg Report 2005, unpublished data

20. MedVeg Bioassays - Ulva * * * * * * * * * * Control site * signif different from control site MedVeg Report 2005, unpublished data

21. MedVeg: Posidonia mortalities with distance MedVeg Report 2005, unpublished data

22. MedVeg: Posidonia mortalities with sedimentation rate Mortality increases rapidly beyond the sedimentation rate of 6g m-2 d-1 MedVeg Report 2005, unpublished data

23. MedVeg: Posidonia density & cover Decrease close to the farms MedVeg Report 2005, unpublished data

24. MedVeg: Posidonia biomass Decrease close to the farms MedVeg Report 2005, unpublished data

25. If monitoring studies indicate a decrease in seagrass meadow extension or shoot density, the amount of waste material (as C, N and P loads) must decrease for a equivalent percentage until recovery of the previous conditions. Alternatively, cages should be moved to other sites, according to guidelines reported above. Concessionaires must present a plan for the monitoring of possible pressures and damages to seagrass beds and include this in the Environmental Agenda for certification ISO14000 and EMAS (Eco-Management and Audit Scheme). A suitable monitoring program must use reliable techniques and include quality control procedures, and should be based on the rapid assessment techniques as described below MedVeg recomendations-2

26. Morphometric descriptors shoot biomass, expressed as the average dry weight of at least ten replicates shoots Physiological descriptors total phosphorus content in different tissues, specifically young leaves and rhizomes, expressed as % of dry weight. total non-structural carbohydratesreserves in rhizomes, expressed as % of dry weight elemental sulphur content (as μmol per g dry weight) in roots. MedVeg descriptors/indicators:at individual plant level

27. At population level shoot density, based in counting the number of shoots inside patches of Posidonia oceanica and expressed as the number of shoots per square meter . At community level epiphyte biomass, expressed as the dry weigh of epiphytes in relation of the size of the shoots. sea-urchin density, based on counting the number of individuals inside patches of Posidonia oceanica and expressed as the number of individuals m-2 MedVeg descriptors/indicators:

28. Our results do not mean that any fish farming activity should be banned at distance less than 800m from anyPosidonia oceanica plant in the Mediterranean. However, adopting this distance could be an appropriate precautionary measure in the vicinity of important and well-developed Posidonia meadows that environmental authorities have set as priority areas for conservation. Whenever a fish farm is located in the vicinity of seagrass meadows, the health of the seagrass meadow should be annually monitored. Working definitions of the term "Posidonia meadow" should be harmonised among Mediterranean countries and common standards are set regarding priorities for conservation of such meadows. Otherwise, it is likely that MedVeg recommendations will be enforced differently in different member states and other Mediterranean countries thereby resulting in both inadequate environmental protection and in violating equal terms of competition within aquaculture industry. However...

29. Mass balance models Karakassis et al. (2005) Sci Mar vol 69

30. Land-based tanks input output • Diel high frequency sampling experiments on fluxes of • Nutrients • POC • PON • Bacteria • tanks containing • different fish sizes • (1, 31 & 53gr) sea bass Tsapakis, Pitta, Karakassis (2006) Aquat. Liv. Resour vol 19

31. Nutrient dynamics Fish size: 1gr Significant difference and Diel pattern in discharge Tsapakis, Pitta, Karakassis (2006) Aquat. Liv. Resour vol 19

32. POC and PON dynamics Significant difference and Diel pattern in discharge Tsapakis, Pitta, Karakassis (2006) Aquat. Liv. Resour vol 19

33. N & P mass balance: % losses over feed input Fish Size (gr) PON (%) NH4 (%) PO4 (%) 1 7 21 13 31 5 29 16 53 7 27 13 Average 6 26 14 Fine particulate material settling at very slow rates and over larger distance from the discharge points Tsapakis, Pitta, Karakassis (2006) Aquat. Liv. Resour vol 19

34. Several studies have failed to detect significant changes in dissolved nutrients, Chl-a and POC concentrations even at fairly short distance from the cages (Pitta et al 1998, La Rosa et al., 2002, MEDVEG unpublished data, Soto & Norambuena 2004) This paradox might be due to: The dispersive nature of the sites (nutrients are rapidly diluted) Inefficient sampling (concentrations vs fluxes) Intensive grazing and transfer to higher trophic levels Combination of the above However

35. filtered Chlorella unfiltered Grazing experiment in Creteusing dialysis chambers 8 6 4 Chl a (mg l-1) 2 0 0 80 200 >500 30 Distance (m) Karakassis et al. (submitted)

36. Analyses • Local Fisheries landings :time series analysis • Environmental: OC, Chla, Nutrients • Fish: Species, Abundance + Biomass per species, diversity, biodiversity, LF, age, condition factor, fecundity, G Index, stomachs, lipids, proteins • Mega: S, A + B per species, diversity, biodiversity • Macro: S, A, B total, diversity • Bacteria: Counts • Micro zoo + Phytoplankton: S, A, B (total), diversity • Fish spatial structure: geostatistics

37. Fish communities The communities differed firstly according the substrate and secondly according to fish-farms presence. The effect of fish-farm presence was mainly quantitative No significant differences in diversity or biodiversity indices (taxon. distinctness etc)

38. Fish communities • The total abundance and biomasswas higher near to fish farms in May – and fairly similar in the recruitment period in September. • It seems that during the recruitment period all sites (Near and Far) are stocked with fish close to the carrying capacity

39. Effects on Landings • Total Landings • Farm Production

40. A B Effects on Landings: MAFA analysis • The correlation between the size of the fishing fleet & the landings trend could be coincidental: due to a clear declining trend because of a vessel withdrawal policy • Rainfall & Temperature did not show any correlation with the common trend (except Chios) • fish-farming production related to an increase of local fisheries landings

41. AQCESS conclusions • No change in macrofauna • Small changes in megafaunal biomass • Big change in fish abundance and biomass documented through: • Before-after study: Machias et al 2004, ECSS, v. 60 • Near-far study: Machias et al 2005, MEPS, v. 288 • Landings: Machias et al. (2006) Aquaculture v. 261 • Hydroacoustics: Giannoulaki et al. 2005, JMBA UK v. 85 • FAD effect? No, the list of species (<30 spp) aggregating near the cages are known (Dempster et al 2002 MEPS for W. Med, Smith et al submitted from the E. Med). Not the ones increasing in the above studies

42. AQCESS conclusions • Not all benthic communities respond in the same way to disturbance • Large long living animals could be more efficient means for monitoring subtle changes • The most possible explanation is the rapid transfer of nutrients up the food web in a nutrient-starving environment

43. sediment: horizontal changes current Eh (mV) TON (%) TOC (%) Cephalonia Ithaki Sounion Karakassis et al. (2000) ICES J mar sci 57

44. Meta-analysis of benthic effects Kalantzi & Karakassis (2006) Mar. Pollut. Bull vol 52

45. Meta-analysis of benthic effects Kalantzi & Karakassis (2006) Mar. Pollut. Bull vol. 52

46. Meta-analysis of benthic effects

47. Sediment profiling imagery (SPI): an «inverted periscope» camera glass mirror

48. SPI images beneath fish farms UF CH4 or H2S Bg FS FS BLT BT BLT Source: Karakassis, Tsapakis, Smith, Rumohr. (2002) Mar Ecol Prog Ser, 227

49. Multivariate analysis of SPI data October February July Euclidean distance fauna SPI Comparisons between multivariate patterns Source: Karakassis, Tsapakis, Smith, Rumohr. (2002) Mar Ecol Prog Ser 227

50. Minimizing monitoring requirements All correlation coefficient values were significant (p<0.001) Lampadariou, Karakassis, Pearson (2005) Mar. Pollut Bull vol 50