DOI: 10.5061/dryad.bnzs7h4jc
title: Data from: Fish responses to manipulated microhabitat complexity in urbanised shorelines

description: The diversity-habitat complexity relationship has been utilised widely in
 conservation and biodiversity enhancement interventions, but few studies
 have attempted to tease apart the components of complexity that drive this
 relationship. The ecological engineering of seawalls is one area where
 this topic has advanced, albeit not at scales relevant to fish. We
 constructed habitat enhancement units (Simple, Complex, and Freestyle
 ‘fish houses’) out of hollow concrete blocks and installed them at the
 base of tropical rip-rap seawalls. Both the Simple and Complex fish houses
 were cuboid, had the same surface area and volume, and included 100 holes
 (microhabitats). The holes in Simple fish houses were all the same size,
 whereas 25 size variations were used in the Complex design
 (volume-independent manipulation of a single complexity element). The
 Freestyle fish house was non-cuboid and had more overall volume,
 microhabitat types and sizes. We examined the volume-independent (Simple
 vs Complex fish houses) and volume-dependent (Freestyle fish house)
 effects of microhabitat complexity on fish taxonomic and functional
 assemblage metrics at two spatial scales and across diel cycles We also
 investigated diurnal and nocturnal fish-microhabitat size relationships.
 There was a modest, but not significant, volume-independent effect of
 complexity on fish assemblages. The Freestyle design supported
 significantly greater abundance, species richness and distinct taxonomic
 and functional compositions. These results were dependent on spatial
 scales and diel cycles. Diel variation in fish activity patterns resulted
 in stronger size-matching relationships between fish and microhabitat at
 night than day. Synthesis and applications. Our study shows that, to
 enhance fish diversity, it is important to provide three-dimensional
 habitat architecture that incorporates a wide range of microhabitat sizes
 and types. Our findings also highlight some key considerations when
 assessing the performance of intervention designs, including spatial-scale
 dependent effects of structural complexity, diel variation in
 fish-microhabitat relationships, and choice of intervention assessment
 metric (i.e. taxonomic vs functional diversity).
description: # Data from: Fish responses to manipulated microhabitat complexity in
 urbanised shorelines [Access this dataset on
 Dryad](https://doi.org/10.5061/dryad.bnzs7h4jc) This dataset is associated
 to the published paper "Fish responses to manipulated microhabitat
 complexity in urbanised shorelines". The study tested whether
 manupulated microhabtat complexity influences fish diversity and
 assemblage composition at two spatial scales (microhabitat and
 whole-structure scales) and across diel cycles as well as diurnal and
 nocturnal fish-microhabitat size relationships. ## Experimental setup and
 sampling protocols We constructed four replicates of three habitat
 enhancement units called 'fish houses' with varying degrees of
 habitat complexitry (Simple, Complex, and Freestyle), made of concrete
 blocks and installed them at the base of rip-rap seawalls in October 2019.
 Both the Simple and Complex fish houses were cuboid, had the same surface
 area and volume, and included 100 holes (microhabitats). The holes in
 Simple fish houses were all the same size, whereas 25 size variations were
 used in the Complex design (volume-independent manipulation of a single
 complexity element). The Freestyle fish house was non-cuboid and had more
 overall volume, microhabitat types and sizes. Fish surveys were conducted
 during daytime and nighttime. Diurnal fish assemblages were surveyed using
 underwater video cameras (1 h per sampling) with six repeated measures in
 March 2020 and July-September 2020 while the night surveys were carried
 out visually via SCUBA diving with five repeated measures in
 August-October 2020. This study examined the volume-independent (Simple vs
 Complex fish houses) and volume-dependent (Freestyle fish house) effects
 of microhabitat complexity on fish taxonomic and functional assemblage
 metrics at two spatial scales and across diel cycles as well as diurnal
 and nocturnal fish-microhabitat size relationships. ## Description of the
 data and file structure The dataset consists of seven files below:
 'day_diversity.csv' and 'night_diversity.csv' contain
 the taxonomic and functional diversity metrics per fish house namely,
 abundance (n), species richness (sr), Shannon’s diversity index (H),
 Pielou’s evenness index (J), functional richness (FRic), Rao’s quadratic
 entropy (RaoQ) and functional evenness (FEve) at microhabitat and
 whole-structure (only for day surveys) scales during daytime and nightime,
 respectively. Microhabitat- and structure-scale abundances were calculated
 based on count per 1 h and MeanCount per frame for day surveys,
 respectively while count per fish house was used for night surveys. Both
 microhabitat- and structre-scale species richness was count of species per
 sampling. For more details on functional traits, please see Supporting
 Information Table S3. 'microhabitat_taxo_composition.csv' and
 'microhabitat_func_composition.csv' contain abundance (count per
 fish house) of each species and community-weighted mean (CWM) values of
 each functional trait per fish house at the microhabitat scale,
 respectively. 'structure_taxo_composition.csv' and
 'structure_func_composition.csv' contain abundance (MeanCount
 per frame) of each species and community-weighted mean (CWM) values of
 each functional trait per fish house at the whole-structure scale,
 respectively. 'size-matching_relationship.csv' includes the
 total length (tl in cm) and body depth (bd in cm) of fish that utilised
 microhabitats within fish houses and the volume of microhabitats utilised
 by them (per observation) during daytime and nighttime. The information
 about hole type and hole volume (cm3) is available in Supporting
 Information Figure S2.