Aquaculture category description form

Please submit a separate form for each type of culture to be described and try to obtain information on as many of the variables listed below as possible

Information provider

Name: Tarzan Legovic

Affiliation or address: R. Boskovic Institute, POB 180, HR-10002 Zagreb, Croatia

Source of information: EIA on aquacultures in Krka estuary, Sibenik, 2005.

Part 1 – General description

a. Country: Croatia

b. Environment

  • Coastal
  • Offshore
  • Estuarine
  • Other (please specify)

c. Type of organisms produced

  • Finfish
  • Mostly Shellfish
  • Algae

d. Availability of support for research (please specify what equipment, facilities are available and how far these are from the proposed study site).

Martinska Research Station of the R. Boskovic Institute, at the Krka estuary,

opposite of the Sibenik town. Two vesels, own port.

Laboratories. Equipment storage. Divers.

Distance to aquacultures: 3 to 10 km.

e. Relationship of the local staff with the fish farm operator (good, bad, other)

Part 2 – Detailed farm description

a. Species produced: Mussels, oysters, seabass, seabream.

b. Annual production level: 400 t mussels, 10 000 oysters, 20 t (seabass, seabream).

c. Gear used (net pens, lines, etc.)

d. Distance to nearby aquaculture farms (how many other farms?)

This is a set of small 26 farms. Other farms are not nearby.

e. Environmental conditions & ecological information

  • Depth: From 20 to 40 m.
  • Sediment type

Rocky on the slopes, sandy on the bottom, occasionally mud.

  • Water conditions (calm, rough)
  • Water quality (all relevant information, e.g. dissolved oxygen, nutrients, etc)

O2: 70 - 110 % of saturation.

PO4 0.03, NO2 0.06, NO3 2.27, SiO4 1.4, NH4 0.6 (ug/l)

DOC 1-2 mg/l, POC: 0.2-0.8 mg/l

  • Range of chlorophyll a levels

Chlorophyll-a: up to 1.5 ug/l

  • Air and water temperature,annual range

Air: 5-35oC. Water: marine layer 12 to 20oC.

  • Salinity range. Sharp salinity gradient at 1 to 3 m below the surface

depending on the river flow.

  • Range of current velocities: 0 to 60 cm/s
  • Water exchange rate (residence time)

Upper brackish layer from 5 days to 30 days depending on the Krka river inflow.

Lower marine layer from 15 days to 6 months depending on the Krka river inflow

and entrainment into the upper brackish layer.

Detailed farm description (cont)

  • Presence of seagrass beds

No.

  • Information on benthic communities

Several transects from the surface to the bottom have been investigated by divers.

Information on benthic community is relatively complete with species list and

densities of organisms.

  • Are there endangered/protected species in the area? what are they?

Pina nobilis.

  • Are there bathymetry data available?

Yes.

Part 3 – Effects of the environment on aquaculture (WP3)

Problems, actual or anticipated – please rate on scale of 0 (very minor) to 4 (serious) and provide detailed description of the problem.

  • Storm damage: negligible
  • Freezing: No.
  • Pollution: Micro: No. Macro: When spotted it is picked up.

Heavy metals: 500 ng Zn /l , 35 ng Pb /l , 180 ng Cu /l , i 10 ng Cd /l

0,5-2,5ng(total Hg)/l, 0,1-0,8ng(dissolved Hg)/l, 0,04-0,75 ug(particulate Hg)/g.

  • Harmful Algal Blooms

Not in the area designated for aquacultures.

  • Disease

Investigated but not found.

  • Predators

Few.

  • Birds

Very few.

Part 4 – Effects of aquaculture on the environment (WP2)

a. Briefly assess the possible adverse, and/or positive, consequences of aquaculture at this site, e.g. altered benthic community, increased water column turbidity, wild fish diseases, eutrophication, risk of escapes and breeding with wild stocks, etc.

Adverse: Accumulation of particles below aquacultures.

Positive: Decrease of a possibility for phytoplankton blooms in the marine layer.

b. List existing marine uses, with emphasis on user-conflicts (e.g. competition for habitat with wild fisheries) and also such issues as stakeholders disturbed by the view of fish pens or by boat motors and fumes, etc.

Marine uses in conflict with aquacultures. Passage of pleasure boats in the proximity of the aquacultures. There is a proposal to limit the trafic in the estuary.

Part 5 – Regulatory issues (WP2)

Which tools, models and indicators are currently used by the regulatory agencies (the "managers") with regard to aquaculture?

EIA, monitoring:

Water column

1. Temperature and pH

2. Salinity

3. Dissolved oxygen

4. Organic matter dissolved an particulate

5. Phytoplankton, chl-a

6. Zooplankton

7. Nutrients.

8. Sanitary- bacteriological (E. coli, total coliforms, streptococus)

9. Suspended particles

10. Sulphur

11. Metals

Sediment

1. Redox potential, organic carbon and nitrogen.

2. Sulphur

3. Metals

4. Specific organic pollution (PCB, PAH)

Fish and sehellfish

1. Deseases

2. Nutritional quality

3. Hydrocarbons and xenobiotics

4. Metals

5. Bacteria (E. coli, total coliforms, streptococus)

6. PSP, DSP and ASP- during higher phytoplankton concentration.

7. Biological effects of metals (metalotioneins)

7. Contents and structure of benthos.

Part 6 - Dissemination (WP6)

Who are the relevant industry representatives? Who are the aquaculturists? Who are the regulators? Who are the other stakeholders?

Representatives: Association of aquaculturists in the Sibenik county.

Aquaculturists are residents of Sibenik county.

Regulators are Ministry of environmental protection, physical planning and construction.

Sibenik county office for development.