Ricerca ProgettiMECOThe ProjectMethodology and activitiesEcologySampling-1

Biological characterization of study sites

SAMPLING FOR THE BIOLOGICAL CHARACTERISATION OF SANDY COASTAL
AREAS USED IN THE MALTESE ISLANDS
 

Sampling Methods

 

Transepts are laid down at pre-determined sites. The number of transepts used are determined by the size of the bay. Ideally the transepts shall traverse the whole length of the bay from the fore shore (mean sea-level) to the more developed dune system (if present) further up shore. 

The transepts are divided into three sub-zones: 
1. Wet zone – intertidal, between low tide and high tide limits; 
2. Dry zone – eulittoral, from high tide marks to the base of the fore dune; 
3. Dune zone (where present). 

Samples and readings are taken at 5m intervals for each transept. Quadrats are used where necessary. In the case of sand collection, the top few cm of sand are brushed away manually to prevent sampling lately shifted sand. 

The quantitative sampling is supplemented by more general sampling including the use of pitfall traps and general searches. 

 

Physical parameters to be measured on sand:

•  Salinity
•  PH
•  Temperature
•  % organic matter
•  water content
•  grain size

 

Species analysis 
Only species which are larger than 1 mm are collected. 

 

Two methods are employed 

•  A standard search method for sampling mobile organisms
•  A sieving method for sampling burrowing organisms

 

Standard search 

•  Walk slowly for 10 minutes along each transept;
•  Scan the sand surface in a band 0.5 m on either side;
•  Capture any mobile organisms encountered and fix on site in 70% ethanol (fix only a few   representative of each species – total numbers can be estimated by direct counting);
• The position of each organism along the transept is noted.

 

Analysis of macrofauna (sieving) 

•  Collect samples at 5 m intervals along the transept (sample collected by a box quadrat 0.15m X 0.15 m);
•  Take top 30 cm and place in sieve (mesh size 1 mm) – dry or wet sieved in water (depending on the wetness of sand;
•  Preserve any organisms retained in sieve in 70% ethanol (to count and identify).

 

Analysis of macroflora 

• Collect contiguous samples using a quadrat starting from fore-dune regione – up shore to dune-soil transition;
•  Identify and estimate the % coverage of each species.