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Context Whilst the composition and arrangement of habitats within landscape mosaics are known to be important determinants of biodiversity patterns, the influence of seascape patterning and connectivity on temperate reef fish assemblages remains largely unknown. Objectives We examined how habitat patterns at multiple spatial scales (100–1000 m) explained the abundance and diversity of temperate reef fish in a reef-seagrass dominated seascape. Methods Fish assemblages were surveyed using remote underwater videos deployed on 22 reefs in Jervis Bay, NSW, Australia. Using full-subset GAMMs, we investigated if habitat area, edge, structural connectivity and a metric for habitat diversity (Shannon’s diversity index) of reef and seagrass can predict variations in a temperate reef fish assemblage. Results A key finding of the study was that temperate reefs close (< 55 m) to large (> 6.25 ha) seagrass meadows contained greater abundance and diversity of fish. A consistent negative correlation was also found between reef area (> 0.01 ha) and the fish assemblage. The influence of seascape metrics on the abundance of fishes varied with functional traits (trophic groups, mobility and habitat associations). Fish-seascape relationships occurred at a range of spatial scales with no single scale being solely important for structuring the fish assemblage. Conclusions We demonstrate that it is important not to view reef habitats in isolation, rather consider a reefs context to adjacent seagrass when predicting the distribution of temperate reef fish. This finding improves current understanding of the multi-scale factors structuring temperate reef fish assemblages and highlights the importance of reef-seagrass connectivty for the management of temperate marine ecosystems.
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Temperate zone coastal seascapes: seascape patterning
and adjacent seagrass habitat shape the distribution
of rocky reef fish assemblages
Daniel S. Swadling .Nathan A. Knott .Matthew J. Rees .Andrew R. Davis
Received: 10 February 2019 / Accepted: 23 August 2019 / Published online: 30 August 2019
ÓSpringer Nature B.V. 2019
Context Whilst the composition and arrangement of
habitats within landscape mosaics are known to be
important determinants of biodiversity patterns, the
influence of seascape patterning and connectivity on
temperate reef fish assemblages remains largely
Objectives We examined how habitat patterns at
multiple spatial scales (100–1000 m) explained the
abundance and diversity of temperate reef fish in a
reef-seagrass dominated seascape.
Methods Fish assemblages were surveyed using
remote underwater videos deployed on 22 reefs in
Jervis Bay, NSW, Australia. Using full-subset
GAMMs, we investigated if habitat area, edge,
structural connectivity and a metric for habitat diver-
sity (Shannon’s diversity index) of reef and seagrass
can predict variations in a temperate reef fish
Results A key finding of the study was that temper-
ate reefs close (\55 m) to large ([6.25 ha) seagrass
meadows contained greater abundance and diversity
of fish. A consistent negative correlation was also
found between reef area ([0.01 ha) and the fish
assemblage. The influence of seascape metrics on the
abundance of fishes varied with functional traits
(trophic groups, mobility and habitat associations).
Fish-seascape relationships occurred at a range of
spatial scales with no single scale being solely
important for structuring the fish assemblage.
Conclusions We demonstrate that it is important not
to view reef habitats in isolation, rather consider a
reefs context to adjacent seagrass when predicting the
distribution of temperate reef fish. This finding
improves current understanding of the multi-scale
factors structuring temperate reef fish assemblages and
highlights the importance of reef-seagrass connectivty
for the management of temperate marine ecosystems.
Keywords Seascape ecology Connectivity
Spatial scale Temperate reef fish Seagrass Full-
subsets generalized additive mixed models
(GAMMs) Remote underwater video (RUV)
Electronic supplementary material The online version of
this article ( con-
tains supplementary material, which is available to authorized
D. S. Swadling (&)A. R. Davis
Centre for Sustainable Ecosystem Solutions and School of
Earth, Atmospheric and Life Sciences, University of
Wollongong, Wollongong, NSW 2522, Australia
N. A. Knott M. J. Rees
NSW Department of Primary Industries, Fisheries
Research, PO Box 89, Huskisson, NSW 2540, Australia
Landscape Ecol (2019) 34:2337–2352,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Further investigation is required to determine how predator-prey interactions influence species richness and abundance across meadow sizes. Furthermore, movement patterns and the abundance of estuarine fish are known to be affected by the quality and proximity of edge habitats (Irlandi and Crawford 1997); however, this relationship is most often demonstrated in adjacent or nearby biogenic habitats (e.g., saltmarsh (Irlandi and Crawford 1997;Baillie et al. 2015), mangrove forests (Jelbart et al. 2007a;Skilleter et al. 2017), kelp (Olson et al. 2019), and reefs (Irlandi and Crawford 1997;Swadling et al. 2019)). Less attention has been paid to the role of non-biogenic edge habitats such as rock and cobble fields in terms of their impact on fish assemblages in adjacent eelgrass meadows. ...
... species movement, foraging activities, predator-prey interaction) of the focal eelgrass nursery habitat. Analyzing eelgrass communities in the context of their surrounding habitats is becoming increasingly common (e.g., Olson et al. (2019); Gilby et al. (2018); Whippo et al. (2018); Swadling et al. (2019)) with results producing valuable insights into the ecology of eelgrass meadows and nearshore areas in general. This suggests that eelgrass meadows, including those in CS and BS, do not function in isolation, but rather are functionally connected to the broader mosaic of habitats across the seascape. ...
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Eelgrass ( Zostera marina ) meadows are important fish habitats in temperate coastal areas. Understanding the relationships between seascape patterns—the spatial and temporal variability of biological and physiochemical drivers—and fish diversity in eelgrass meadows is crucial to conserving and managing these important habitats. The main objective of this study was to determine the environmental variables that influence the diversity of fish in eelgrass meadows in British Columbia, and whether a rich mosaic of edge habitats is positively associated with species richness and diversity, owing to the increased niche dimensionality and foraging opportunities provided by heterogeneous adjacent habitats. Using a spatiotemporal multispecies model based on long-term eelgrass fish diversity monitoring program data (2004–2020), we found that seascape variables, particularly those derived from unmanned aerial vehicles (meadow area, edge habitat heterogeneity), explained the most variation in species occurrence and abundance. We also found a positive effect of edge habitat heterogeneity on species richness in small and medium-sized meadows, with higher species richness and diversity in small and medium-sized meadows with high edge habitat heterogeneity. The relationship between edge habitat heterogeneity and species richness and diversity in large meadows was less clear. We also found that species richness has declined through time while diversity has been variable through time, remaining relatively stable in one region and generally decreasing in the other region. This analysis provides key insights into how seascape variables influence the distribution of species and the diversity of fish assemblages in nearshore eelgrass habitats in British Columbia.
... The growth of human populations, overexploitation of natural resources and climate change are modifying ecosystems globally, increasing habitat degradation and unpredictably altering habitat complexity [11][12][13], resulting in impacts on biodiversity [14], Working across six estuaries that include some of the most impacted P. australis meadows in south-eastern Australia, we quantify how habitat complexity (seagrass density, meadow fragmentation and distance to meadow edge) is related to: (1) fish abundance and species composition, (2) mobile epifauna abundance, (3) fish predation rates and (4) erosion rates. As marine fauna and processes can respond to complexity at different spatial scales [56], we used a seascape approach that incorporates variability at different levels including sub-patch (e.g., seagrass shoot scale; e.g., seagrass shoot scale; [57]), withinpatch e.g., distance to meadow edge; [40]) and among-patch (connectivity) or seascape scale [58]. Seascape ecology is a growing field of marine science that brings spatial approaches common in terrestrial landscape ecology into marine ecosystems to help resolve spatial patterns [59,60]. ...
... Individual fish can rely on different habitats, move among them with the tides, time of day and during different stages of their life [29]. The presence of different surrounding habitats may enhance fish abundance and species [58] as they tend to prefer habitats with high diversity and high connectivity [87]. A more detailed interrogation including seascape variables such as distance from natural reefs, mangroves and saltmarshes may contribute to explaining some of the patterns. ...
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Habitat complexity plays a critical role in shaping biotic assemblages and ecosystem processes. While the impacts of large differences in habitat complexity are often well understood, we know less about how subtle differences in structure affect key ecosystem functions or properties such as biodiversity and biomass. The late-successional seagrass Posidonia australis creates vital habitat for diverse fauna in temperate Australia. Long-term human impacts have led to the decline of P. australis in some estuaries of eastern Australia, where it is now classified as an endangered ecological community. We examined the influence of P. australis structural complexity at small (seagrass density) and large (meadow fragmentation) spatial scales on fish and epifauna communities, predation and sediment erosion. Fine-scale spatially balanced sampling was evenly distributed across a suite of environmental covariates within six estuaries in eastern Australia using the Generalised Random Tessellation Structures approach. We found reduced erosion in areas with higher P. australis density, greater abundance of fish in more fragmented areas and higher fish richness in vegetated areas further from patch edges. The abundance of epifauna and fish, and fish species richness were higher in areas with lower seagrass density (seagrass density did not correlate with distance to patch edge). These findings can inform seagrass restoration efforts by identifying meadow characteristics that influence ecological functions and processes.
... The raster file was resampled into a pixel size of 7x7 m 2 and projected into UTM WGS84. Seascape pattern analysis was carried out at a scale of 1000 m, which is the maximum scale selected in previous studies, for example [12]. This scale was measured for radius with a coordinate of 46 stations at its center (figure. ...
... Area and perimeter of seagrass patches were selected for detecting the relationship between seagrass meadows and reef fish [14]. The area and edge of reef patches were the metrics to examine the influence of reef characteristics on the fish assemblages [12], while Shannon's diversity index was selected as a representative metric of reef complexity [3], and see table.1 for seascape metrics. ...
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We examined the effect of mangrove, seagrass meadows, reef characteristics, and complexity of seascape heterogeneity on reef fish assemblages in Ternate, Natuna and Bintan-Indonesia. The analytical approach of seascape ecology was undertaken, using field survey data of reef fish community and maps of mangrove covers and habitat benthic. The fish data had been collected during reef health monitoring in 2015 through the Coral Reef Rehabilitation and Management Program-Coral Triangle Initiative. Map of benthic habitats and mangroves was provided by Indonesia’s data custodians in 2015-2016. Generalized Additive Models were performed to analyze non-linear and non-monotonic relationships. The results showed that mangroves and seagrasses were essential for reef fishes, and as expected, reef characteristics were also important. Accordingly, the conservations of coral reefs should consider mangrove and seagrass protection and vice versa. Therefore, this information could be considered for managers of marine protected areas (MPA) to better practice MPA management.
... Ikan menjadi salah satu biota laut yang membutuhkan mangrove, terumbu karang, dan lamun untuk kelangsungan hidupnya. Ketiga ekosistem tersebut memiliki pengaruh terhadap persebaran ikan dan proses ekologi yang terjadi di dalamnya yang membuat adanya konektivitas antara ekosistem pesisir dengan ikan itu sendiri (Ricart et al., 2018;Swadling et al., 2019). Konektivitas tersebut dapat terjadi saat ikan melakukan mobilisasi ke sekitar ekosistem mangrove dan terumbu karang untuk mencari makan (Mumby, 2006). ...
... Radius tersebut juga dipilih berdasarkan home range dari komunitas ikan yang ditemukan. Berdasarkan penelitian oleh Swadling et al. (2019) dan Ulumuddin et al. (2021) Setelah membuat dataset kemudian dilakukan analisis korelasi untuk memeriksa korelasi antara kedua matriks tersebut. Hasil korelasi yang dijalankan pada software RStudio menghasilkan tabel korelasi yang memuat koefisien korelasi tiap matriks. ...
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Ikan karang selama hidupnya dapat mendiami satu habitat saja atau melakukan migrasi ke ekosistem di sekitarnya. Faktor tersebut membuat terjadinya interaksi antara ikan karang dengan ekosistem mangrove dan terumbu karang. Pendekatan bentang laut (seascape ecology) masih belum banyak dilakukan mengingat pendekatan ini penting untuk mengetahui kelimpahan ikan yang berada di sekitar area terumbu karang, sehingga dapat dijadikan sebagai pedoman dalam pengelolaan kawasan pesisir. Oleh karena itu penelitian ini bertujuan untuk mengetahui struktur bentang laut (seascape), interaksinya dengan ikan karang, dan menilai tingkat konektivitas dari keduanya di Raja Ampat dan Maluku Tenggara. Metode penelitian yang digunakan yaitu pengolahan dan analisis data spasial dan statistika menggunakan software QGIS 3.14 dan RStudio versi 2.0.4. Hasil penelitian dari analisis data statistika menggunakan analisis korelasi dan regresi diperoleh bahwa kelimpahan Ikan Lutjanidae pada Pulau Kei Kecil, Maluku Tenggara memiliki konektivitas dengan nilai regresi tertinggi yang dijelaskan oleh metrik Distance to Mangrove (DistM) dengan nilai koefisien korelasi sebesar -0,88; R2 0,7777; dan nilai AIC (Akaike Information Criterion) 18,01. Berdasarkan hasil penelitian, kesimpulan yang diperoleh adalah matriks Distance to Mangrove (DistM) menjadi matriks yang memiliki hubungan erat dengan Ikan Lutjanidae yang dapat mempengaruhi kelimpahan Ikan Lutjanidae di lokasi penelitian. Reef fish, during their lifetime, can inhabit only one habitat or migrate to the surrounding ecosystem. These factors make the interaction between reef fish with mangrove ecosystems and coral reefs. However, the seascape ecology approach is still not widely used, considering that it is important to determine the abundance of fish around coral reef areas, so that it can be used as a guideline in the management of coastal areas. Therefore, this study aims to determine the structure of the seascape, its interaction with reef fish, and assess the level of connectivity of both in Raja Ampat and Southeast Maluku. The research method used is the processing and analysis of spatial and statistical data using software QGIS 3.14 and RStudio 2.0.4. The results of statistical data analysis using correlation and regression analysis showed that the abundance of Lutjanidae on Kei Kecil Island, Southeast Maluku had connectivity with the highest regression value described by the Distance to Mangrove (DistM) metric and has a correlation coefficient value of -0.88; R2 0.7777; and the AIC (Akaike Information Criterion) score of 18,01112. Based on the results of the study, the conclusion obtained is that the Distance to Mangrove (DistM) metric is a metric that has a close relationship with Lutjanidae fish which can affect the abundance of Lutjanidae fish in the research location.
... This generally positive influence of seagrass coverage on fish abundance was expected, as seagrass is well known as important habitat for many juvenile fish (Heck et al., 2003;Swadling et al., 2019). Here, we assume that fish found at the mangrove sites during high tide are conducting tidal migrations, to or through seagrass patches. ...
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Mangroves often support rich fish and crustacean communities, although faunal abundance and diversity show strong spatiotemporal variability. Consistent patterns in mangrove animal communities might be dictated by forest characteristics, by seascape context or by some combination of these factors. Predicting drivers of spatial heterogeneity in mangrove faunal communities can better support the zoning of forests for management purposes, for example by identifying sites important for fisheries nursery provision. We sampled 14 sites within a large (4000 ha) mangrove forest in Kenya, quarterly over a period of 2 years. There were clear and consistent differences in the quality of sites for fish and crustacean abundance and diversity. Forest characteristics (as summarised by the complexity index, CI) and seascape metrics (the presence, area and configuration of contiguous seagrass) were strong predictors of site differences. However, they showed opposite influences on dominant members of the fish and crustacean faunas, with CI correlated negatively with fishes and positively with crustaceans, and seagrass area correlated positively with fishes and negatively with crustaceans. Synthesis and applications . Sites within the same mangrove forest exhibit consistent differences in fish and crustacean abundance. However, the fish and crustacean communities (and particularly dominant species within them) act differently in response to forest and seascape characteristics. Old growth, mature forest, set in a seascape of seagrass patches with bare sediment, was associated with highest crustacean abundance. In contrast, denser smaller trees and seascapes with larger, continuous areas of seagrass correlated better with fish abundance. Zoning for management, as mandated in new Kenyan policy, will need to consider these differences in seascape use between fish and crustaceans.
... This, along with the occurrence of other vulnerable species in the ecotone areas surveyed, typically associated with soft-bottom habitats such as G. galeus, highlights the need to adequately manage these transitional environments, including both reefs-and their adjacent soft-bottom habitats. While for reef fishes with high levels of site attachment the protection of small areas could be effective, the variability in the ecological features of fishes mainly associated with soft-bottom and pelagic habitats may demand larger protected areas and the consideration of landscape issues for monitoring, management and conservation plans (Moore et al., 2011;Rees et al., 2014;Reis-Filho et al., 2019;Swadling et al., 2019). Current findings about ecotone areas contribute to the existing knowledge of the ecological role of different habitats in the Southwestern Atlantic Ocean surveyed using BRUVs (e.g., Alves-Bezerra et al., 2022;Reis-Filho et al., 2019;Rolim et al., 2019). ...
/// Link to full article: /// We investigated changes in the structure of coastal fish assemblages in Northern Patagonia, Southwestern Atlantic, by using baited remote underwater video stations (BRUVS) deployed at increasing distances from rocky reefs: 0–5 m, 15–20 m and 50–60 m. We estimated species richness and abundance (total and by preferred habitat type) and searched for diagnostic species in each distance range. We recorded 14 taxa across 11 families in 19 areas surveyed. Species richness and abundance were higher on reef ledges and decreased with distance from them, at a finer spatial scale than previously reported. Acanthistius patachonicus and Sebastes oculatus were indicative of reef ledges; they were less abundant at 15–20 m and disappeared at 50–60 m. Callorinchus callorynchus and Odontesthes spp. occurred only at distances >15–20 m from the reefs, while Galeorhinus galeus was distributed homogeneously throughout the surveyed area. Our findings have practical implications for monitoring ecotone demersal habitats with BRUVS.
... T A B L E 1 Summary of the fragmentation metrics and anthropogenic disturbance variables. Blank ('-') minimum and maximum values for anthropogenic disturbances indicate that variables were not included in the analyses at the respective scale The fragmentation metrics used in this study were types of spatial pattern metrics, which are routinely applied to quantify changes in the composition and configuration of patches in both landscape (McGarigal, Cushman & Regan, 2005;Schindler et al., 2013) and seascape ecology (Sleeman et al., 2005;Wedding et al., 2011;Swadling et al., 2019). The fragmentation metrics selected (Table 1) were patch density (PD), landscape division (LD), area-weighted mean perimeter to area ratio (AWMPAR) and mean radius of gyration (2016) and Santos et al. (2022), but was adapted to include the number of holes metric as follows: ...
• Although it is well established that human activities are linked to the loss of seagrasses worldwide, the influence of anthropogenic disturbances on the habitat fragmentation of seagrass meadows is less understood. This information is essential to identify how humans are modifying seascapes and what disturbances pose the greatest risk to seagrasses, which is pertinent given the rapid urbanization occurring in coastal areas. • This study examined how the habitat fragmentation of an endangered seagrass Posidonia australis varied in relation to several anthropogenic disturbances (i.e. human population, marine infrastructure, terrestrial run-off and catchment land-usage) within 10 estuaries across 620 km of coastline in New South Wales, Australia. • When comparing between estuaries, the fragmentation of P. australis meadows was significantly greater in estuaries adjacent to highly populated metropolitan centres – generally in the Greater Sydney region. At sites within estuaries, the density of boat moorings was the most important predictor of habitat fragmentation, but there was also evidence of higher fragmentation with increased numbers of jetties and oyster aquaculture leases. • These results suggest that the fragmentation of seagrass meadows will become more pervasive as the human population continues to grow and estuarine development increases. Strategies to mitigate anthropogenic disturbances on seagrass meadow fragmentation could include prohibiting the construction of boat moorings and other artificial structures in areas where seagrasses are present or promoting environmentally friendly designs for marine infrastructure. This knowledge will support ongoing management actions attempting to balance coastal development and the conservation of seagrasses.
... The first groups were indicated by the reefs that had mangroves within a 1000-3000m radius from the center of the station. The distance between sites and the presence of mangroves were taken into account in the reef fish home range (Swadling et al. 2019). According to this criteria, there are eight stations located near mangrove habitats and six stations with an absence of mangroves ( Figure 1). ...
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Utama RS, Renyaan J, Nurdiansah D, Makatipu PC, Suyadi, Hapsari BW, Martha E, Rahayu EMD, Sugiharto A. Akbar N. 2022. Diversity of reef fish species in presence of mangrove habitat in Ternate, North Maluku, Indonesia. Biodiversitas 23: 5184-5193. Research on reef fish has been widely reported, where information about reef fish communities is an important factor for evaluating fisheries management and coral reef management. Mangroves as the nursery, foraging, and growing areas were also important to assure sustainable reef fish fisheries. This paper studies reef fish abundance and diversity in Ternate Waters in the presence of mangrove in coral reef habitats. To determines coral reef condition underwater photo transect was performed while an underwater visual census (UVC) was used to determine the abundance and diversity of reef fishes in Ternate waters between 2017 and 2018. A total of 14 stations were used, with eight stations near the mangroves and six stations that did not contain mangroves. Based on the observation, fish species richness in mangrove absence was higher than in the presence of mangroves, with 68 and 65 species in 2017 and 66 and 62 species in 2018. However, the abundance of reef fish was recorded high in the presence of mangroves than in the absence of mangroves, with 390 and 289 individual differences in 2017 and 2018. Mangroves' complexity affected part of reef fish communities in Ternate water, particularly Lutjanidae, Serranidae, and Scaridae, which might influence the abundance of reef fishes rather than the species richness. In addition, carnivore shows a negative effect in the presence of mangroves, in contrast with herbivores. It is related to mangrove functioning as a temporary shelter when high-pressure presence in their natural habitat (reef) and a place for foraging. Therefore, mangrove management must be a consideration in the coral reef or fisheries management program.
... One possible explanation for this result is the tendency towards more frequent movements between adjacent eelgrass and reef habitats. Swadling et al. (2019) found greater fish density and diversity on temperate reefs near seagrass beds, and Obaza et al. (2015) noted higher piscine predator abundance in nighttime surveys of eelgrass beds. Therefore, fishes found in eelgrass beds further from reef habitats may not travel to nearby reef areas. ...
Eelgrasses Zostera are foundation species that perform myriad ecosystem services, yet research into their habitat function is often focused on regions susceptible to intense anthropogenic disturbance. This trend has created a data gap on the role more remote eelgrass beds provide among the mosaic of other temperate marine habitats. In this study, we surveyed 15 Z. marina and Z. pacifica beds along Catalina Island and the Southern California Bight (SCB) mainland coast from 2018 to 2020 for areal coverage, structural components and fish assemblages, from which a relativized index of fish utilization was then created. We then evaluated the landscape and structural components that potentially drive fish utilization in Z. marina using the index as a response variable in a model selection procedure. Zostera beds ranged in size from 0.06 ha to >27.5 ha. Fish assemblages in Z. marina and Z. pacifica beds were significantly different, and in the case of fishes found in both, individuals were often below size at maturity in Z. marina and above size in Z. pacifica. Distance to the nearest reef and bed area, both positively related to the fish assemblage index, were the most important factors. The results suggest Z. marina beds function as a nursery habitat while Z. pacifica are used by mid-level predators for foraging. These data represent the first rigorous study of fish utilization of open-coast Z. marina and Z. pacifica beds, and are invaluable to marine spatial planning efforts that may incorporate a more holistic approach to habitat management in temperate regions.
... (2) Build a water body model: ere are two ways to create a water body model: one is to use the parametric modeling tool Unity3D water body to set relevant parameters (including water energy, ripple, reflection) according to the direction, drop and other related conditions, etc.) to complete Modeling of the river water system; First, when the dynamic effect of the water system is not high, the texture of the water body can be simulated with 3DMax [37,38]. e method is simple, the amount of data is small, and it can meet the general conditions. ...
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Traditional villages refer to the villages that formed earlier, are rich in traditional resources, and have various values and must be protected. This paper aims to study how to draw three-dimensional landscapes of traditional villages based on the big data information system. This paper puts forward the problem of 3D landscape rendering, which is based on big data and modeling, and then elaborates around the concept of data mining and related algorithms and designs and systematically tests 3D landscape rendering. The experimental results show that when the number of rendered patches is less than 120193 between 120193 and 242029, the system can run smoothly. It can achieve acceptable and relatively smooth operation; when it exceeds 242029, the system is obviously stuck. The design scheme of the three-dimensional landscape geographic information system of the traditional villages is reasonable and feasible, the operation is stable, and the expected research goals are achieved.
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Knowledge of connectivity and population structure is integral to the sustainable management of fished populations, yet such information is unavailable for many species over scales relevant to their exploitation. We examined broad-scale patterns and drivers of adult movement for a putatively mobile carangid (Pseudocaranx georgianus) on Australia’s southeast coast using an angler tag-recapture dataset. More than 6300 individuals were tagged and released across 1007 km of coastline, with anglers recapturing 157 (2.48%) individuals during a 14-year period. Median distance moved was 5 km and a substantial proportion of individuals (19%) were recaptured at their release location. Recapture latitude was also strongly predicted by release latitude (r2 = 0.87). However, a broad range of movements were observed (0–508 km), with 6% of individuals moving further than 100 km. Most individuals recaptured in areas now designated as Marine Protected Areas (MPAs) were originally released in the same area (79.2%). Larger body size, longer periods at liberty, and releases during Spring all positively influenced distance moved. Results support restricted movement over an intermediate scale, punctuated by occasional large movements. Our findings suggest adult movement of P. georgianus in southeastern Australia primarily occurs over smaller distances than the current spatial scale of management.
Marine ecology seeks to understand the factors that shape biological communities. Progress towards this goal has been hampered by habitat‐centric approaches that ignore the influence of the wider seascape. Coral reef fishes may use non‐reef habitats (e.g. mangrove and seagrass) extensively, yet most studies have focused on within‐reef attributes or connectivity between reefs to explain trends in their distribution and abundance. We systematically review the evidence for multihabitat use by coral reef fishes across life stages, feeding guilds and conservation status. At least 670 species of “coral reef fish” have been observed in non‐reef habitats, with almost half (293 species) being recorded in two or more non‐reef habitats. Of the 170 fish species for which both adult and juvenile data were available, almost 76% were recorded in non‐reef habitats in both life stages. Importantly, over half of the coral reef fish species recorded in non‐reef habitats (397 spp.) were potential fisheries targets. The use of non‐reef habitats by “coral reef” fishes appears to be widespread, suggesting in turn that attempts to manage anthropogenic impacts on fisheries and coral reefs may need to consider broader scales and different forms of connectivity than traditional approaches recommend. Faced with the deteriorating condition of many coastal habitats, there is a pressing need to better understand how the wider seascape can influence reef fish populations, community dynamics, food‐webs and other key ecological processes on reefs.
Seagrass habitats worldwide are degrading and becoming fragmented, threatening the important ecosystem services they provide. Fauna associated with seagrasses, particularly cryptic species, are expected to respond to these changes, but are difficult to detect at ecologically meaningful scales using non-extractive techniques. We used a small, wide-angle camera (GoPro) and a small quantity of bait positioned within the canopy of Posidonia australis meadows in Jervis Bay, New South Wales to assess the response of fishes to seagrass cover. We saw a clear positive relationship with the condition of P. australis; a high cover of this seagrass had positive effects on the diversity and abundance of cryptic fauna. Our findings highlight ecosystem shifts associated with the loss and fragmentation of biogenic habitat. These changes are of particular relevance for P. australis meadows given their current status as an endangered ecological community in several locations in NSW and their slow rate of recovery from disturbance.
Habitat classes are often used as surrogates to represent or capture species assemblages in the design of spatial conservation strategies, such as multi-use marine protected areas (MPAs). Little research, however, has critically evaluated how well habitat classes can reliably predict species distributions and abundances over scales relevant to spatial planning. In this study, we used hierarchical models to quantify spatial variability in demersal and mid-water fishes at multiple scales to determine whether habitat classes are appropriate surrogates for temperate fishes. Baited remote underwater video systems (BRUVS) and mid-water BRUVS were used to sample fish assemblages in Jervis Bay, NSW, Australia, over rocky reef, seagrass Posidonia australis and unvegetated sediment among locations (>3 km), habitat classes (~400 m) and sites within habitats (~200 m). Each habitat class displayed a distinct assemblage of demersal fish driven by many species and families showing strong habitat associations (e.g. platycephalids and labrids). In contrast, the mid-water fish assemblage and certain demersal families, such as habitat generalists (e.g. sparids), showed no differentiation among habitat class. Considerable variation in the fish assemblage was also observed among locations. Seascape connectivity explained much of this variability, as reefs surrounded by large areas of seagrass harboured a greater abundance and diversity of fishes. Overall, we provide quantitative support for the use of habitat classes as surrogates for most temperate fishes. Spatial planners, however, need to be aware of species-specific relationships with habitat and the importance of seascape patterning when using habitat-based surrogates for MPA design.
The spatial properties of landscapes influence numerous ecological attributes on land and in the sea, including the efficacy of conservation areas. In this context, seascape connectivity (landscape connectivity in the sea) has been shown to modify reserve performance in low‐energy marine ecosystems (e.g. coral reefs, mangroves, seagrass), but it is not clear whether similar spatial linkages also shape reserve effectiveness on high‐energy, exposed coastlines. We used the surf zones of ocean beaches in eastern Australia as a model system to test how seascape connectivity and reserve attributes combine to shape conservation outcomes. Spatial patterns in fish assemblages were measured in 12 marine reserves and 15 fished beaches, across two thousand kilometers of exposed coastline, using baited remote underwater video stations. Reserve performance was shaped by both the characteristics of reserves, and the spatial properties of the coastal seascapes in which reserves were embedded. More fish species and a greater abundance of harvested fishes were recorded in surf‐zone reserves that had three key attributes: i) they encompassed a sizeable area of surf‐zone habitat (>1.5 km of coastline); ii) were located close (<100 m) to rocky headlands; and iii) included pocket beaches in a heterogeneous seascape. Conservation outcomes for exposed coastlines might, therefore, be enhanced by prioritizing sufficiently large areas of seascapes, with strong linkages to abutting complementary habitats. Our findings have broader implications for coastal conservation planning, which is limited by the absence of empirical data to describe how the ecological features of high‐energy shorelines influence conservation outcomes, and we suggest that seascape connectivity might have similar ecological effects on reserve performance on both sheltered and exposed coastlines. This article is protected by copyright. All rights reserved
Nocturnal studies of fish assemblages are relatively rare, particularly at depths greater than 100 m, despite the relevance of diel shifts in habitat usage to fisheries management. This study assesses fish diversity and abundance from remotely operated vehicle (ROV) video recordings that were collected by industry during the day and at night in the course of a subsea pipeline survey, at 130 m depth. A total of 34,862 fish from 41 species and 25 families were recorded along the 23 km of pipeline. The pipeline was characterised by a high abundance of commercially important snapper (Lutjanidae) and grouper (Epinephelidae) species. The fish assemblage sampled along the pipeline during the day differed markedly to that sampled at night time. Several ubiquitous predatory species, e.g. Epinephelus areolatus, Lutjanus quinquelineatus, Lutjanus russellii, where present during the day but not at night, likely moving off the pipeline to feed in nearby habitats. Structurally complex mesophotic epibenthic habitat forming invertebrates were observed on the pipeline including; mesophotic corals, crinoids (featherstars), gorgonocephalids (basket stars), hydroids, true anemones and sponges, but elsewhere in the region, historical trawling effort is thought to have removed such organisms and extensively modified the original habitat. These complex epibenthic habitats were considered to be important to commercial target species and the modification or loss of these habitats is thought to have negatively impacted the valuable commercial fisheries in the region. This study suggests pipelines can offer a significant epibenthic habitat and refuge for fish, potentially comparable to the historical habitats lost to trawling. Fish diversity and abundance was observed to be consistently greater where a gap/crevice existed beneath the pipeline and many species were frequently observed in conjunction with the complex invertebrate matrix above the pipeline, under spanning sections beneath the pipeline and at the pipeline-sediment interface, regardless of time of day. Further dietary analysis, spatially explicit fisheries modelling and off-pipeline surveys on the natural seafloor are required to further investigate the ecological value of pipelines and its influence in fish behaviour. The study builds knowledge of mesophotic coastal fish ecology and will help to inform discussions regarding the ecological and fisheries implications of decommissioning and the removal of subsea infrastructure.
This book describes an array of power tools for data analysis that are based on nonparametric regression and smoothing techniques. These methods relax the linear assumption of many standard models and allow analysts to uncover structure in the data that might otherwise have been missed. While McCullagh and Nelder's Generalized Linear Models shows how to extend the usual linear methodology to cover analysis of a range of data types, Generalized Additive Models enhances this methodology even further by incorporating the flexibility of nonparametric regression. Clear prose, exercises in each chapter, and case studies enhance this popular text.
This study investigated variations in the composition and biomass of demersal fish assemblages over a 570-metre depth gradient on the temperate, lower west coast of Australia (32° S) in the south-eastern Indian Ocean. Fish assemblages were sampled using Baited Remote Underwater Stereo Video systems (stereo-BRUVs, n=284 deployments) from shallow waters around a mid-shelf island (Rottnest Island) to the continental slope within a submarine canyon (Perth Canyon). A total of 9013 individual fishes (i.e. ΣMaxN) belonging to 179 species and 75 families were identified. Multivariate statistical analyses revealed three distinct fish assemblages associated with the continental shelf (5–199 m), margin (200–300 m) and upper slope (300–570 m). A distance-based linear model revealed that among environmental covariates, benthic biota (sessile invertebrates and macroalgae) accounted for the highest proportion of variation in fish assemblage composition (16.9%) followed by depth (12.5%) and seabed relief (10.5%). Generalised additive models indicated higher biomass of fish associated with habitats characterised by benthic biota. Species richness decreased with increasing depth across the continental shelf but remained constant with increasing depth on the continental slope. Average fish length was not correlated with depth but was greatest at 200–400m depth. The continental margin and upper slope habitats revealed a distinct change in assemblage composition as well as a peak in biomass of species that was dominated by larger-bodied meso-predators at the continental margin. The trends exhibited in fish assemblage characteristics across this broad depth range can inform ecosystem based management for deepwater fisheries resources.