Project title: Conditions, resources, enemies and biodiversity: Forces structuring marine communities of the shallow Adriatic Sea - COREBIO
Croatian:  Uvjeti, resursi, neprijatelji i bioraznolikost: Sile koje oblikuju morske zajednice u plitkom Jadranskom moru

Funding: HRZZ - Hrvatska Zaklada za Znanost / Croatian Science Foundation

Duration: 48 months   
Start date: 01.10.2014   
End date: 30.09.2018.

Project summary:  This project is an investigation of the major drivers offish community structure in the shallow Adriatic Sea of Croatia. This information is crucial for the sustainable, scientific management of coastal ecosystems, as required by EU instruments such as the Habitats Directive, Marine Strategy Framework Directive, Water Framework Directive, and the Common Fisheries Policy.

The major questions asked are:

  1. What are the ecological baselines in Croatia in community structure?
  2. How does anthropogenic activity (harvesting, coastal development) shift community structure from baseline?
  3. How do marine protected areas maintain functional communities?
  4. How is community structure changing over time?

We will investigate these questions using innovative, non-destructive techniques for quantifying fish abundance and size distribution, and benthic habitat quality. These techniques include lure-assisted, underwater visual census which was originally developed in the Schultz laboratory; baited, underwater video; and DGPS¬assisted, towed underwater video.

EU policies require that non-destructive methods for assessment and monitoring replace destructive harvest-based methods currently in widespread use, and these methods are among the most scientifically supported non-destructive methods currently available. These methods will be used to quantify fish community structure and benthic habitat at all major MPAs and former MPAs in Croatia, to compare communities within MPAs to matched locations outside MPAs.

Matched locations will be chosen to test for specific anthropogenic drivers of community structure, such as high fishing pressure, coastal development, marine tourism, aquaculture, and terrestrial runoff. These results will advance our basic understanding of coastal ecosystems, and will be crucial for satisfying Croatia's responsibilities as an EU citizen in MPA construction, management, and monitoring of marine res ources.

Project leader:
prof. dr. sc. Stewart Schultz, University of Zadar

Team members:

doc. dr. sc. Claudia Krushel, University of Zadar

Dubravko Pejdo, mag., University of Zadar

prof. dr. sc. Alen Soldo, University of Split, Odjel za studije mora
doc. dr. sc. Tatjana Bakren-Petricioli, University of Zagreb, Faculty of Science
univ.bacc. Donat Petricioli, D.I.I.V. ltd, Zagreb



Baited, remote underwater video.  Eels Conger conger and Murena helena visiting a sardine bait station on the island of Kurba, Kornati NP, October 2014.  Eels are nocturnal stalk-attack predators in tight spaces, such as dense seagrass, here Posidonia oceanica.  We use BRUV to quantify fish size and assemblages associated with environmental variables such as benthic habitat and human activity, including fishing intensity and shoreline development.



Diver-operated stereovideo fish censusCOREBIO uses this method for high-resolution census of fish size and habitat use, allowing high statistical power for quantification of benthic habitat preferences and avoidance.  We have discovered that most fish prefer heterogeneous edge habitats, usually associated with rock, and avoid homogeneous habitats such as homogeneous seagrass, sand, or rock. From top to bottom: loggerhead sea turtle Caretta caretta, striped seabream Lithognathus marmoratus, salemo porgy. Sarpa salpa, and brown wrasse Labrus merula encountered at Šilo Velo, Kornati NP, Croatia, September 2015.

Geopositional underwater videography. COREBIO uses this method for monitoring benthic habitats at permanent transects that are revisited using submeter accuracy differential GPS (EGNOS differential correction real time).  Illustrated above is a surface-based towfish method, suitable for shallow habitats < about 10 m depth.  Pictured is a transect through a meadow of the seagrass Posidonia oceanica at Kornati NP, October 2014.

Lure-assisted visual fish census. COREBIO uses this method for censusing fish species and observing fish behavior.  Kruschel and Schultz have demonstrated that this method is more successful than traditional visual census for quantifying sedentary and cryptic species, which move out of hiding to visit the lure.  Shown above is a brief demonstration of the method as employed at Kornati NP in September 2015.   In the lower video, the lead lure is dropped on a monofilament line, and two individual Coris julis can be seen visiting the lure.


Research results. Following are summaries of major COREBIO results to date.  These summaries are ongoing as data arrives to be analyzed.

Year 1

Theory of monitoring: shifts from baselines in seagrass metrics

BRUV as a method for assessing community baselines in Adriatic fish

Year 2

Habitat preference of fish species as revealed by lure-assisted visual census

Environmental risk assessment with baselines

Abundance ratios in/out of species for MPAs in Croatia

Relative abundance of fish species in response to shoreline development

Fish biodiversity inside/outside MPAs as revealed by BRUVs

Conference participation




Year 1 accomplishments: 

1. RAC/SPA Marine Vegetation Conference, presentation by Stewart T. Schultz.

2. Hiring of Dubravko Pejdo.

3. Training of graduate students in stereovideography by Dr. Jim Seager (Event Measurement, Calibration).

4. Upgrading of equipment (BRUV: underwater lights and additional systems).

5. Stakeholder roundtable discussion of COREBIO goals, methods, and socioeconomic impacts.  Presentations by Stewart T. Schultz, Dubravko Pejdo, and Ivana Zubak at the Main Ballroom, University of Zadar.

6. Multiple BRUV field deployments at Kornati NP and adjacent locations outside the NP by Dubravko Pejdo and Claudia Kruschel, .

7. Multiple benthic habitat RUV field deployments at Kornati and Dugi Otok by Stewart T. Schultz, Tatjana Bakran-Petricioli, and Donat Petricioli.

8. Publication of PLOS ONE paper: Error, Power, and Blind Sentinels: The Statistics of Seagrass Monitoring.


Year 2 accomplishments: 

1.  Habitat preferences, abundance and diversity, MPA and human effects in Brijuni and Kornati, community ordinations, habitat videography, catchability for BRUV higher than for trammel nets.

2.  Bait is optimized, Trimble R1 up and running, qGIS set up for Kornati NP GIS, 1-meter photographic resolution, new towfish with two camera system, laptop for realtime GPS tracking on the GIS.

3.  BRUV, LUVC, GRUV, DOV completed in Brijuni and Kornati, LUVC additional sampling in many other locations in Croatia, 6 BRUVS each day for four days inside and 4 days outside, over 2 km benthic video transects in Brijuni and Kornati

4.  EMBS conference, CIESM conference presentations of COREBIO results on baseline indicator theory, Kornati in/out results for Scorpaena

5.  New BRUVs constructed, cameras purchased, cables rebuilt