Table 1. Macro-habitat categories of the sampled transects in the Rio Formoso Estuary. Data are as follows: number of transects performed (total transects), number of transects in which seahorses were sighted (seahorse transects), and average density of seahorses found in each type of macro-habitat.

Density values are given as mean ± confidence interval (range).

Macro-habitat type	Total transects (n)	Seahorse transects (n)	Density ( ind./m2)
I—Dense mangrove: characterized by the presence of a dense mangrove on the banks of the river, with a large presence of submersed roots, leaves, and fallen branches of mangrove trees, mainly Rhizophora mangle, which contributes to the formation of complex habitats favoring the presence of secondary habitat components, such as sponges, algae, oysters, and octocorals.	73	48	0.032 ± 0.011 (0–0.34)
II—Sparse and/or tidal flat mangrove: mangroves present on the banks of the river with more sparse distribution, with the presence of clearings and, consequently, lower availability of submersed roots. In these places, tidal flats can also form during the lower tides, with the roots being totally or partially uncovered. They may also contain the secondary habitat components associated with the mangrove roots mentioned for type I habitat but in smaller quantities.	23	13	0.019 ± 0.011 (0–0.1)
III—Reef environment: formed mainly by rocky (inorganic) reefs with algae, coral, and sponge coverage.	9	0	0
IV—Algae and sponge banks: banks formed by agglomerates of different species of algae or sponges or, in some cases, with the presence of both.	3	2	0.006 ± 0.005 (0–0.0)
V—Sandy substrate with rocks: environment composed of sandy bottom and sparsely distributed rocks, which might contain algae or sponge coverage.	17	2	0.001 ± 0.001 (0-0.01)