File Name: coral reef fishes dynamics and diversity in a complex ecosystem .zip
Santander No. Such a steep gradient facilitates the identification of patterns of variation in species abundance and diversity along depth.
Table of Contents New Book on the Crisis. The Lab and The Blog. Targeted Research Project. Coastal Zone management in the Arabian Gulf.
Coral Reef Fishes
While there is increasing evidence for habitat specialization in coral reef fishes, the extent to which different corals support different fish communities is not well understood. Here we quantitatively assess the relative importance of different coral species in structuring fish communities and evaluate whether sampling scale and coral colony size affect the perceived strength of fish-habitat relationships. Fish communities present on colonies of eight coral species Porites cylindrica , Echinopora horrida , Hydnophora rigida , Stylophora pistillata , Seriatopora hystrix , Acropora formosa , A.
Additionally, the differences in fish communities supported by three coral species P. Substantial differences in fish communities were observed across the different coral species, with E. Coral species explained more of the variability in fish species richness For three focal coral species, a greater amount of total variation in fish species richness and fish abundance was evident at a larger scale of sampling.
Together, these results indicate that the structure of reef fish communities is finely tuned to coral species. Loss of preferred coral species could have profound effects on reef fish biodiversity, potentially more so than would be predicted on the basis of declining coral cover alone. Editor: Heather M. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are available at doi: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exists. Habitat characteristics are known to play a key role in structuring natural communities [ 1 — 2 ]. In many ecosystems, living organisms create biogenic habitat that provides critical resources for a wide variety of mobile species.
For example, terrestrial forest biomes form the habitat structure essential for the survival of many insects, birds and mammals [ 3 — 5 ]. Likewise, macro-algae and seagrasses have a similar habitat-forming role in freshwater and temperate marine ecosystems [ 6 — 7 ].
Numerous studies have examined relationships between the abundance of focal species and the areal cover of biogenic habitat [ 8 — 10 ], however, the strength of these relationships may depend on the level at which organisms discriminate among habitat types [ 11 — 12 ]. If focal organisms are highly specialised and discriminate among habitat-forming species, then habitat availability should be measured at the species level.
In addition, the strength of the relationships between organisms and their habitat may depend on the scale of sampling [ 13 ]. Organism-habitat relationships may be obscured if inappropriate taxonomic resolution or spatial scale of sampling are applied [ 14 — 16 ]. Therefore, to understand population and community responses to degrading habitats, it is necessary to understand these species and scale-specific phenomena. On coral reefs, the complex structure of scleractinian corals produces a diversity of habitat types that provide shelter, food and sites for reproduction for other reef organisms [ 17 — 19 ].
Coral cover is often considered the key variable that influences the abundance of coral-reliant organisms [ 8 , 20 ]. However, there is increasing evidence that many organisms preferentially associate with particular coral species or coral morphologies at critical stages of their development [ 12 , 19 , 21 — 24 ]. For example, Bonin [ 23 ] demonstrated that new recruits of at least four damselfish species Chrysiptera parasema , Pomacentrus moluccensis , Dascylus melanurus and Chrosmis retrofasciatus had a strong preference for a limited number of Acropora species.
Hence, measures of overall coral cover may fail to detect species-specific habitat associations that are important in explaining the diversity of reef communities.
Some studies have shown that the presence of different coral species influences the structure of fish communities and identified the characteristics of the corals likely to be responsible for these differences [ 21 — 23 , 25 — 26 ]. For example, Messmer et al. Acropora nasuta and Seriatopora hystrix. The physical characteristics of coral species that attract and support a high diversity and abundance of fishes may relate to the branching structure of the coral colonies [ 21 — 22 , 25 ]. In general, structurally more complex habitats tend to support more diverse and abundant animal communities by providing a greater variety and number of refuge sites, which in turn can decrease encounter rates between competitors as well as between predators and their prey [ 27 — 29 ].
Consequently, structurally complex coral species are predicted to support richer and more abundant fish communities. The observed relationships between fish diversity or abundance and the structure of the coral community may also be dependent on the spatial scale of sampling. At very small spatial scales of sampling, fish-habitat associations may appear to break down due to patchy distribution of individuals [ 15 , 30 ].
In contrast, at a large spatial scale, habitat patchiness can become homogenised and other environmental characteristics, such as depth and currents, become more important in structuring fish communities [ 14 — 16 , 21 ].
Therefore, the spatial scale of sampling of different corals could have a significant effect on the perceived relationships between the coral community structure and the structure of fish communities [ 31 ]. Understanding habitat associations of coral reef fishes is critical given the differential susceptibility of coral species to increasing temperatures and other stressors associated with climate change [ 23 , 32 — 34 ].
A decline in the abundance of particular coral species could have significant effects on fish communities if those coral species support diverse and abundant fish assemblages. Understanding the influence of coral species, coral structural complexity and coral colony size on fish communities will assist efforts to predict the likely consequences of coral loss to reef fish communities [ 18 , 36 ]. The overall aim of this study was to assess the influence of coral species, sampling scales and coral colony size in structuring reef fish communities.
We compared the abundance and richness of fish assemblages at Lizard Island on the Great Barrier Reef across a range of common coral species to determine if:. This research did not involve any endangered or protected species and no animals were sampled. The Lizard Island lagoon is relatively shallow with a maximum depth of approximately 15 meters and with the majority of reefs situated in three to six meters depth. The lagoon is sheltered from the prevailing southeast swell and has well developed reefs around its margins.
To determine if some species of coral support more diverse and abundant fish communities than others, we compared fish community structure among eight of the most commonly occurring coral species in the Lizard Island lagoon: Porites cylindrica , Echinopora horrida , Hydnophora rigida , Stylophora pistillata , Seriatopora hystrix , Acropora formosa , A. These species have a complex branching structure, but differ in characteristics such as average branch length, branch density, overall colony morphology, and maximum colony size.
In order to provide quantitative physical and structural descriptions of the eight coral species, we conducted different physical measures on multiple colonies of each study coral species. These measurements were used to classify corals as species with high and low structural complexity. Inter-branch space of 8—16 colonies of each of the eight coral species were measured to determine if there were significant differences in physical characteristics.
Additionally, the branch length was measured for the six coral species with a branching morphology: A. Ten random distances between branch tips and the length of ten randomly selected branches were measured to the nearest millimetre using callipers or a ruler for longer branches. Corals were randomly sampled from around the lagoon of Lizard Island. ANOVA and Kruskal-Wallis tests were used to examine differences in branch length and inter-branch space, respectively, among the coral species.
The mean of ten branch lengths six coral species was calculated for each coral colony before performing ANOVA. Branch length was log10 transformed to meet the assumptions of normality and homoscedasticity Section A in S1 Supporting Information. The mean of ten inter-branch spaces eight coral species was also calculated for each coral colony before performing nonparametric independent samples Kruskal-Wallis test, as the data did not meet the assumptions for ANOVA Section A in S1 Supporting Information.
The analysis was performed using SPSS. To determine if some species of coral support more diverse and abundant fish communities than others, we compared fish community structure among the eight coral species selected for the study listed above. A minimum of five haphazardly selected colonies of each coral species were sampled at 0. Only colonies that showed no obvious signs of disease, bleaching or partial mortality were used.
The fish assemblage occupying each coral colony up to 0. During the first three minutes all the larger and more obvious fishes were counted from a distance of approximately one meter.
For the following three minutes the spaces between branches were carefully and systematically searched for cryptic fish species. Only individuals that appeared to use the coral head or hovered above the coral head for the entire time of the observation were recorded. Fish that swam past the coral head during the observation period were not counted. Individuals were identified to species level and a life stage for each individual was recorded adult, juvenile, new settler.
Fish species richness, total fish abundance, and fish community structure were compared among the eight coral species that were sampled at 0. ANOVA was used to test for significant differences in fish species richness and total fish abundance among the eight coral species.
Fish species richness and fish abundance were log10 transformed to meet assumptions of normality and homoscedasticity Section B in S1 Supporting Information. The 16 most abundant and frequently occurring fish taxa minimum of 4.
Life stages of each fish taxa new settlers, juveniles and adults were considered separately in the analysis. The data for these fish species were pooled together to form higher classification groups: Gobiodon , Pomacentrids, Pomacentrid juveniles, Labrids, Other Juveniles and Other New Settlers.
Further pair-wise PERMANOVA tests were conducted as a post hoc test to identify which coral species were significantly different from each other in fish community structure. The data for this analysis were fourth root transformed prior to analysis to reduce the influence of extreme values of highly abundant fish species.
Unrestricted permutations of raw data and Type III sums of squares were used to generate P -values due to the unbalanced design. Bootstrapped values were calculated over replications per coral species. To determine if the spatial scale of sampling influenced the relationship between fish community structure and coral species identity, single-species coral stands of P.
The spatial scales were selected based on the site attached behaviour and relatively small home ranges of the majority of the encountered fish species and on the availability of the study coral stands. Due to differences in growth forms, these were the only three of the eight coral species that could be sampled at all three spatial scales.
A minimum of six haphazardly selected healthy colonies of each coral species were sampled at each spatial scale Table 1. In most instances, individual coral colonies that closely matched one of the sampling scales were chosen.
The size of each coral colony was estimated with a measuring tape. In a few instances 2x2 m scale only , the area surveyed was a portion of a larger coral colony. In these instances, a 2x2 m quadrat was haphazardly placed over the coral to delineate the sample area. Each coral colony was sampled at only one spatial scale. Fish assemblages were quantified as described above. Additionally, water depth and reef zone within the lagoon were recorded for each sampled coral.
A regression tree approach [ 39 ] was used to explore and describe the relationships between coral species, fish species richness and fish abundance at the three different scales. Depth and reef zone were also included in the analysis to account for their potential effects on the fish variables. Fish abundance was log10 transformed to reduce the influence of extreme values Section C in S1 Supporting Information.
Absolute deviations were used to estimate tree branching and the size of trees was selected by cross-validation, choosing the tree with the smallest estimated predictive error. Regression tree analysis was used because it is suited to the exploration of relationships between ecological communities and multiple environmental variables and where the sampling of variables may be unbalanced, where missing values occur, or where there are non-linear relationships between the ecological community and the environmental variables [ 39 ].
The analysis was performed using the TreesPlus S-Plus statistical computer package [ 39 ]. To determine if different coral species accumulate fish species richness and total abundance at different rates with increasing colony size we compared the relationship of these traits to colony size for the three coral species for which a range of colony sizes was available: P. Colony maximum height, width and length were measured to the nearest centimetre.
All fish present within the colony and up to 0. The branches of each colony were carefully searched for cryptic species.
Coral decline threatens fish biodiversity in marine reserves
Reef fish community structure on three islands of Itaipu, Southeast Brazil. We provide here the first assessment of the composition, abundance and distribution of rocky reef fishes of Itaipu Sound, Rio de Janeiro, off the southeastern Brazilian coast. A total of individual fish, belonging to 29 families and 42 species were recorded. The most abundant fish species were Parablennius pilicornis, Haemulon steindachneri, Orthopristis ruber and Diplodus argenteus. Sheltered and complex habitats showed the most abundant and diverse fish populations. There was a major significant separation between sampling sites and a secondary seasonal pattern.
While there is increasing evidence for habitat specialization in coral reef fishes, the extent to which different corals support different fish communities is not well understood. Here we quantitatively assess the relative importance of different coral species in structuring fish communities and evaluate whether sampling scale and coral colony size affect the perceived strength of fish-habitat relationships. Fish communities present on colonies of eight coral species Porites cylindrica , Echinopora horrida , Hydnophora rigida , Stylophora pistillata , Seriatopora hystrix , Acropora formosa , A. Additionally, the differences in fish communities supported by three coral species P. Substantial differences in fish communities were observed across the different coral species, with E.
The worldwide decline in coral cover has serious implications for the health of coral reefs. But what is the future of reef fish assemblages? Marine reserves can protect fish from exploitation, but do they protect fish biodiversity in degrading environments? The answer appears to be no, as indicated by our 8-year study in Papua New Guinea. A devastating decline in coral cover caused a parallel decline in fish biodiversity, both in marine reserves and in areas open to fishing.
David W. Copeia 1 February ; 1 : — Peter F.
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