Seasonal fish abundance and seagrass cover data, Zanzibar, Tanzania 2014-2015

We conducted a field survey in four
sites around Unguja Island (Zanzibar, Tanzania): two no-take MPAs (Chumbe and
Mnemba Islands)  and two unprotected, fished sites (Changuu island
and Mnemba reef).
The study was conducted during three
seasons in 2014-2015: November-December 2014, April-May
2015 and July-August 2015. Sampling was carried out in sub-tidal
seagrass beds dominated by Thalassodendron ciliatum.
At each site, fish and seagrass sampling
was conducted in 10 replicate transects (except in one of the MPAs, where only 7
transects could be sampled due to the limited size of the protected seagrass
bed), which were randomly placed > 5 m apart and parallel to the shore. The
surveys were carried out during high neap tide (± 3 h) through underwater
visual census by snorkelling along 25×4 m belt transects. A snorkeler swam the transects twice during approx. 10 min. All fish observed within or
crossing the transect were counted, identified to the lowest taxonomic level
possible (usually species), and their body length was visually estimated to the
nearest 5 cm. Based on the estimated sizes, all individual fish were then grouped
into three age classes (juveniles, subadults and adults). The bottom per cent cover of
seagrass was visually estimated within 0.25 m² quadrates placed at 5 m intervals along
each transect (resulting in six subsamples per transect).