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Survey techniques used in Halimeda kanaloana (A-D) and Avrainvillea sp. meadows Largebodied species were surveyed visually (A) or photographically (B). Unidentified species were collected with small spears (C). Small-bodied epibenthic fishes were surveyed by injecting a clove-oil solution under a 1.5 m weighted tarp (D). The anesthetized fishes were collected with fine-mesh nets and preserved for subsequent identification. Diver conducting a visual survey of Avrainvillea sp. meadow (E). Note the denser canopy.
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The invasive macroalgal species Avrainvillea sp. and native species Halimeda kanaloana form expansive meadows that extend to depths of 80 m or more in the waters off of O‘ahu and Maui, respectively. Despite their wide depth distribution, comparatively little is known about the biota associated with these macroalgal species. Our primary goals were t...
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Context 1
... All surveys were conducted between June 14th, 2005 andJune 12th, 2006. Initial surveys consisted of visual censuses supplemented by collections made with pole spears. All other surveys were conducted using tandem visual surveys combined with collections using clove-oil anesthetic in order to better assess the numbers of small epibenthic fishes (Fig. 2). For these collections, an anesthetic solution of 10% clove oil in 90% ethanol was aspirated from a squirt bottle beneath a 1.5 m weighted plastic tarp. The tarp was placed haphazardly over either sand or canopy. The solution was allowed to work for a period of 10 min, during which the diver conducted visual- and photographic surveys ...
Citations
... The mounds alter the benthos through increased sedimentation, which modifies hard substrate to resemble soft sediment habitats (Foster et al., 2019;Littler et al., 2004). The alga's ability to engineer habitat structure, its complex branching and holdfast morphology (Littler & Littler, 1992;Olsen-Stojkovich, 1985), and its possible herbivore-deterring secondary metabolites (see Hay et al., 1990) have all influenced the surrounding ecosystem by contributing to significant shifts in surrounding invertebrate (Foster et al., 2019;Longenecker et al., 2011), algal (Peyton, 2009;Smith et al., 2002), and fish communities (Langston & Spalding, 2017). ...
The relative rates of sexual versus asexual reproduction influence the partitioning of genetic diversity within and among populations. During range expansions, asexual reproduction often facilitates colonization and establishment. The arrival of the green alga Avrainvillea lacerata has caused shifts in habitat structure and community assemblages since its discovery in 1981 offshore of Oʻahu, Hawai‘i. Field observations suggest this species is spreading via vegetative reproduction. To characterize the reproductive system of A. lacerata in Hawai‘i, we developed seven microsatellite loci and genotyped 321 blades collected between 2018 and 2023 from three intertidal sites at Maunalua Bay and ʻEwa Beach. We observed one to four alleles at multiple loci, suggesting A. lacerata is tetraploid. Each site was characterized by high genotypic richness ( R > 0.8). However, clonal rates were also high, suggesting the vegetative spread of A. lacerata plays a significant role. The importance of clonal reproduction for the persistence of A. lacerata in Hawai‘i is consistent with the ecological data collected for this species and observations of other abundant macroalgal invaders in Hawai‘i and other regions of the world. These data demonstrate the necessity for implementing appropriate population genetic methods and provide insights into the biology of this alga that will contribute to future studies on effective management strategies incorporating its reproductive system. This study represents one of the few that investigate green algal population genetic patterns and contributes to our understanding of algal reproductive system evolution.
... meadows, seagrass and other macroalgae habitats are known to provide valuable nursery habitats for reef fish settlement and recruitment (Sambrook et al. 2019;Tang et al. 2020;Sievers et al. 2020). Although this function has not been extensively tested in MCEs, Halimeda meadows are known to support diverse mesophotic fish communities (Langston and Spalding 2017;Spalding et al. 2019), and we found these habitats on deep outer reef slopes and in lagoons of all the Coral Sea reefs surveyed. Given their isolation from other coastal nursery habitats, these habitats may be particularly important for the early life stages of fishes and invertebrates, and thereby the replenishment and maintenance of Coral Sea populations. ...
Seamounts and remote oceanic islands serve as valuable natural laboratories in which to study patterns and processes in marine biodiversity. A central hypothesis arising from studies of these systems is the ecological function of seamounts as stepping-stones for dispersal and population connectivity. Evidence of this mechanism exists for a range of taxa, including coral reef fishes, but is still lacking from many tropical seamounts in remote regions. In this study, we used remotely operated vehicles and baited remote underwater video systems to survey fish and benthic communities between 1 and 100 m on seamounts in the Coral Sea Marine Park (CSMP), Australia. We found evidence to support the stepping-stone model of ecological connectivity from new observations of 16 coral reef fishes which have previously not been recorded by quantitative surveys in the region. The widespread distribution of many of these species throughout the full latitudinal extent of the CSMP suggests that there is greater connectivity between mesophotic habitats in the Coral Sea and surrounding biogeographic regions than previously known. We also found a wide variety of mesophotic habitats and recorded significant depth range extensions for 78 fishes in these habitats. This further highlights the potential role of increased habitat area and heterogeneity in a stepping-stone effect throughout the region. Four of the fish occurrence records represent significant range extensions into the Coral Sea from adjacent biogeographic regions, and 13 fishes recorded by this study in the CSMP are not known from the neighbouring Great Barrier Reef, despite its close proximity. Although the Coral Sea remains relatively understudied, these findings suggest that larger-scale models of marine biogeography are relevant to communities in the region, particularly at mesophotic depths. Given the extent and the spatial arrangement of seamounts in the Coral Sea, our findings emphasise that the region is an important link between the centre of marine biodiversity in the Coral Triangle and the Southwest Pacific. Greater mesophotic sampling effort and genetic studies are necessary to understand the nature of connectivity and to establish the role of regional seamount chains, like the Coral Sea reefs, in broader marine biogeographic processes.
... and providing habitat for cryptic fish (Langston & Spalding, 2017) and invertebrates (Fukunaga, 2008). ...
The Papahānaumokuākea Marine National Monument, Hawai‘i, is one of the most isolated and protected archipelagos in the world, making it a natural laboratory to examine macroalgal-microbial diversity because of limited direct anthropogenic impacts. We collected the most abundant macroalgae from nine sites ranging from shallow subtidal (1.5 m) to mesophotic (75 m) depths around Manawai (Pearl and Hermes Atoll). We characterized the macroalgal bacterial communities via high-throughput amplicon sequencing and compared the influence of host phylum, species, site, and depth on these relationships at a single atoll. Ochrophyta species had the lowest bacterial diversity compared to Chlorophyta and Rhodophyta. Site and/or depth may influence the microbial community structure associated with Microdictyon setchellianum , indicating a possible disconnect of these microbial communities among habitats. Chondria tumulosa , a cryptogenic species with invasive traits, differed in associated microbiota compared to the native Laurencia galtsoffii , an alga from the same family collected at the same site and depth. While there was overlap of bacterial communities across sites for some algal species, the majority had minimal macroalgal-microbial community connectivity across Manawai. This mesophotic system, therefore, did not appear to be refugia for shallow water coral reefs at microscopic scales. Additional studies are required to identify other significant influences on microbial community variation.
... meadows, seagrass and other macroalgae beds are known to provide valuable nursery habitats for reef fish settlement and recruitment (Sambrook et al. 2019;Tang et al. 2020;Sievers et al. 2020). Although this function has not been extensively tested in MCEs, Halimeda beds are known to support diverse mesophotic fish communities (Langston and Spalding 2017;Spalding et al. 2019) and we found these habitats on deep outer reef slopes and in lagoons of Coral Sea reefs. Given their isolation from other coastal nursery habitats, these habitats may be particularly important for the early life stages of fishes and invertebrates, and thereby the replenishment and maintenance of populations. ...
Seamounts and remote oceanic islands provide valuable natural laboratories in which to study patterns and processes in marine biodiversity. A central hypothesis arising from studies of these systems is the ecological function of seamounts as stepping stones for dispersal and population connectivity. Evidence of this mechanism exists for a range of taxa, including coral reef fishes, but is still lacking from many tropical seamounts in remote regions. In this study, we used remotely operated vehicles and baited remote underwater video systems to survey fish and benthic communities between 1-100m on seamounts in the Coral Sea Marine Park (CSMP), Australia. We found evidence to support the stepping stone model of ecological connectivity from new observations of sixteen coral reef fishes which have previously not been recorded by quantitative surveys in the region. The widespread distribution of many of these species throughout the full latitudinal extent of the CSMP suggests that the there is greater connectivity between mesophotic habitats in the Coral Sea and surrounding biogeographic regions than previously known. We also found a wide variety of mesophotic habitats and recorded significant depth range extensions for seventy-eight fishes in these habitats. This further highlights the potential role of increased habitat area and heterogeneity in a stepping stone effect throughout the region. Four of the fish occurrence records represent significant range extensions into the Coral Sea from adjacent biogeographic regions and thirteen fishes recorded by this study in the CSMP are not known from the neighbouring Great Barrier Reef, despite its close proximity. Although the Coral Sea remains relatively understudied, these findings suggest that larger-scale models of marine biogeography are relevant to communities in the region, particularly at mesophotic depths. Given the extent and the spatial arrangement of seamounts in the Coral Sea, our findings emphasise that the region is an important link between the centre of marine biodiversity in 3 the Coral Triangle and the Southwest Pacific. Greater mesophotic sampling effort and genetic studies are necessary to understand the nature of connectivity and, to establish the role of regional seamount chains, like the Coral Sea reefs, in broader marine biogeographic processes.
... The number of species and abundance of Gobiidae of Bepondi is significantly higher than Liki and Miossu. It is concluded that Halimeda influences the abundance of Gobiidae, as previous research of Langston and Spalding (2017) in the Main Hawaiian Islands (MHI). ...
Coral fish groups have a very strong dependence on coral reef ecosystems. Nusa Manggala Expedition was carried out for twenty days to explore basic data on the diversity of species of coral reef fish in the Liki, Bepondi, and Miossu Islands. Assessment of coral fish assemblages using Underwater Visual Census (UVC). Four hundred and thirty-two species of fifty families of reef fishes found during the 2 nd session the Nusa Manggala expedition in Liki, Bepondi, and Miossu islands, northern Papua. Four species (Mobula tarapacana, M. alfredi, Oxymonacanthus longirostris, Bolbometopon muricatum, and Plectropomus areolatus) and one species (Cheilinus undulatus) categorized of IUCN as Vulnerable (VU) and Endangered (EN), respectively, were recorded in this study. There is unique pattern of reef fishes' composition in small outer islands location in pristine location that shows Pomacentridae and Labridae were almost in the same number as Gobiidae, Apogonidae, Serranidae, Chaetodontidae, and Acanthuridae. In addition, the results showed that the Liki and Miossu islands and Bepondi Island included at the Coral Fish Diversity Index (CFDI) as an extraordinary and excellent category of marine fish, respectively. The results of the expedition showed that the Liki Islands and Miossu Island had an extraordinary category of marine fish, and Bepondi Island had an excellent category of sea fish. The culture of local people in Papua called "Sasi" prove to provide full protection to the ecosystem and have a positive impact on high diversity of reef fishes.
... The red mangrove stands interrupt shallow sandflats that are home to the endemic Hawai'ian shrimp goby Psilogobius mainlandi, which co-occurs in burrows with the native snapping shrimp Alpheus rapax (Langston and Spalding 2017). Other mutualistic shrimp/goby pairs are abundant throughout the Pacific, but P. mainlandi is the only shrimp-associated goby that occurs in Hawai'i (Karplus and Thompson 2011). ...
... sandflats has negative effects on shrimp/goby burrowing. Other studies have found these same shrimp/goby pairs to be deterred by cover over the benthos; sandflat invasion of the alga Halimeda kanaloana is associated with much lower densities of these mutualist burrow-dwellers (Fukunaga 2008, Langston andSpalding 2017). In our experiment, nearby shrimp were apparently able to quickly perceive and colonize newly available habitat upon debris removal, despite their poor eyesight (Zeng and Jaafar 2012). ...
Hawai‘ian ecosystems evolved in relative isolation and support an abundance of native and endemic species. As such, they are particularly vulnerable to introduced species that alter habitat and interfere with species interactions. Although mangroves are valued globally for shoreline protection and other services, their invasion of the Hawai‘ian islands may have negative effects on the abundance and functions of native species. On an island in Kāne‘ohe Bay, O‘ahu, we explored the relationship between invasion of the red mangrove, Rhizophora mangle, and abundance of the native burrowing shrimp Alpheus rapax, which shares its burrows with the endemic goby Psilogobius mainlandi in a mutualism that reduces predation on both. We hypothesized that the abundance of shrimp/goby burrows is reduced beneath mangroves due to increased cover associated with mangrove prop roots, which trap leaves and debris and may harbor the invasive red alga Gracilaria salicornia. At 3 mangrove-invaded sites, we conducted a survey of burrow density and benthic debris and found ~4-5× lower burrow density and 4× greater cover of debris under the mangrove edge compared to sandflats that were 1.5 and 5.0 m away. Burrow density was negatively correlated with total cover of benthic debris and with subgroups of that cover composed of G. salicornia or leaves. We tested the effect of debris removal over 2 weeks, which resulted in 3-8× more burrows. Thus, we provide evidence that invasive red mangroves, through trapping leaves and pro moting presence of invasive G. salicornia among their prop roots, have strong negative effects on shrimp/goby burrow density. Although our study was limited in spatial scope, we propose that current efforts to remove mangroves in Hawai‘i, for both cultural and ecological reasons, will mitigate negative effects on endemic goby and native shrimp habitat.
... meadows and maërl beds can form complex three-dimensional habitats in an otherwise two-dimensional environment, thus providing habitat and shelter for numerous species, supporting a high degree of species and trophic group diversity, as well as important feeding and reproduction areas for marine life (e.g. Jackson et al. 2001;Barbera et al. 2003;Langston and Spalding 2017). For this reason, they should be the focus of interest/research initiatives as well as of protection measures in order coastal development be carried out in a way that minimizes the damage over the most sensitive and valued aspects of nature (Sahla et al. 2016). ...
At the time Cabo Girão natural marine park was proposed (2016) and later when it was established, (2017), its effective conservation and marine spatial planning goals were hampered by the scarce knowledge on the sea floor habitats and biotic patterns inside the area. In the present work, a combination of different datasets and underwater surveys was used to produce the first habitat map of the Natural Marine Park of Cabo Girão, which is also the first habitat map for Madeira island. Five major habitats were identified, including two previously unknown for Madeira — Avrainvillea canariensis meadows and maërl beds. 132 marine taxa (macroflora, macrofauna and fishes) were identified, including 18 commercially important species and three vulnerable fish species. The results show that the methods used are useful to produce reliable information with limited resources. The information obtained is a tool for conservation and marine spatial planning, which allows for improved policy-making and better management. This study provides a baseline for the benthic habitats of this MPA against which future marine biodiversity changes can be recognised.
... This alga may also change the community diversity and structure across invaded reefs. Langston and Spalding (2017) recorded a higher abundance of fishes above open sand versus within A. amadelpha canopy; Longenecker et al. (2011) determined that removal of A. amadelpha returned invertebrate communities to compositions observed in unaffected regions. All of these traits combine to make A. amadelpha a formidable competitive presence across reefs. ...
Algal assemblages are critical components of marine ecosystems from the intertidal to mesophotic depths; they act as primary producers, nutrient cyclers, and substrate providers. Coral reef ecosystems can be disrupted by stressors such as storm events, effluent inundation, sudden temperature shifts, and non-native invaders. Avrainvillea amadelpha is an invasive green alga that was first recorded in the main Hawaiian Islands on the west shore of Oahu and has continued to be of concern due to its extreme competitiveness with native algae and seagrasses. It has spread rapidly across the island of Oahu, decreasing the biodiversity of the benthos from shorelines to ∼90 m depth. We employed a boosted regression tree modeling framework to identify highly vulnerable regions prone to invasion. Our model indicated that regions exposed to minimal bottom currents and at least five degree heating weeks are particularly susceptible to A. amadelpha colonization. Additionally, we extrapolated our model to the main Hawaiian Islands and forecasted how a 25% increase in statewide annual maximum degree heating weeks may change habitat suitability for A. amadelpha. Across all islands, we identified particularly vulnerable “hotspot” regions of concern for resource managers and conservationists. This manuscript demonstrates the utility of this approach for identifying priority regions for invasive species management in the face of a changing climate.
... Pyle et al. (2016a, b) provide the most recent summary of Hawaiian MCE fishes. They are not ubiquitous, but occur in a broad array of MCE habitats, including black coral beds (Boland and Parrish 2005), Leptoseris beds within the 'Au'au Channel , macroalgal meadows (Langston and Spalding 2017), and limestone ledges associated with ancient sea-level stands (Brock and Chamberlain 1968). Species diversity varies among and within habitats. ...
... Although macroalgal communities generally do not comprise major habitats for large-bodied fishes in the MHI (either on MCEs or shallow reefs), endemic reef-associated fishes were found in macroalgal (Microdictyon spp.) beds at mesophotic depths in the NWHI (Kane et al. 2014). Cryptic fishes also inhabit mesophotic algal beds (Langston and Spalding 2017), and larger, predatory fish such as jacks (Carangidae) have been observed foraging in these algal beds in the MHI (Spalding 2012). Additional studies are needed on MCEs in adjacent areas with and without dense macroalgal beds or meadows to further refine the potential role of macroalgae as mesophotic habitat for reef fishes in both the MHI and NWHI. ...
... The depth-related community structure of reef fishes from the archipelago generally conform to patterns observed worldwide. Overall, fish abundance and herbivores decrease with depth (Fukunaga et al. 2016;Asher et al. 2017a, b;Kane and Tissot 2017), despite the presence of large macroalgal meadows in MCEs Langston and Spalding 2017). The most-abundant fishes in Hawaiian MCEs are planktivores and benthic-feeding invertivores (Fig. 25.8; Brock and Chamberlain 1968;Parrish and Boland 2004;Pyle et al. 2016a;Asher et al. 2017a, b;Fukunaga et al. 2017a, b;Kane and Tissot 2017). ...
The Hawaiian Archipelago is one of the largest and most isolated island chains in the world, and its marine ecosystems are well-studied. Research on Hawaiian mesophotic coral ecosystems (MCEs) began in the 1960s and has intensified during the past decade. In Hawai‘i, rich communities of macroalgae, corals and other invertebrates, and fishes inhabit MCEs and are associated with increased water clarity and decreasing average current strength with depth. Extensive calcified and fleshy macroalgal beds are found both in discrete patches, dense beds, and meadows over both hard and soft substrates. Several species of corals typical of shallow reefs extend to depths of ~60 m. The dominant corals below 60 m are in the genus Leptoseris, which can form extensive coral reefs spanning tens of km². Few octocoral species inhabit shallow reefs and upper MCEs (30–70 m) but are diverse at the deepest range of MCEs (>130 m). Sponges do not represent a major structural component of MCEs. Many species of fishes occur on both shallow reefs and MCEs, but MCEs harbor more endemic species (up to 100% endemism). Several new species of macroalgae, corals and other invertebrates, and fishes have recently been documented. Over 60% of the territorial waters surrounding the archipelago are protected as the Papahānaumokuākea Marine National Monument; however, no specific protections exist for MCEs. Generally, threats affecting Hawai‘i’s shallow reefs also affect MCEs to varying degrees. MCEs may be more insulated from some threats but more vulnerable than shallow reefs to others (e.g., water clarity).
... This contrasts with what we observed, where algae benthic cover at 20 m (19.0 ± 2.20 SE) was greater than that at 45 m (7.6 ± 1.92 SE) (Figure 7), thus making sponges the most abundant, dominant, and important taxa at upper mesophotic reefs in Guánica. Additional attention should be given to any local increase of biological threats to these deeper reefs, such as cyanobacterial mats, known to disrupt benthic community assemblages (de Bakker et al., 2017), opportunistic benthic algae blooms (Langston and Spalding, 2017;Sherman and Tuohy pers. obs.), and the aggressive overgrowing colonial ascidian (Trididemnum solidum) known to overgrow corals (e.g., Rodríguez-Martínez et al., 2012;JEGH pers. ...
The benthic and fish communities of the central portion of the Guánica, Puerto Rico shelf edge were studied to determine species abundance, distributions and species overlap between two depth stratifications, 20 and 45 m, at eight sites. A total of 67 fish species belonging to 21 families were identified. Similar species richness estimates were observed between depths, though fish assemblage composition differed significantly, with observable changes in feeding guild contributions of herbivore and omnivore (20 m) to a deeper assemblage composed of piscivores and planktivores (45 m). Coral assemblages consisted of 31 species at 20 m and 11 species at 45 m, accounting for 17.0% (±1.76 SE) and 2.6% (±0.89 SE) benthic cover for the altiphotic and mesophotic surveys, respectively. The altiphotic and mesophotic coral reef communities support different scleractinian coral assemblages with minimal species overlap. Altiphotic surveys of sponges yielded a higher species richness than mesophotic, with 60 and 54 species respectively, and an overall total of 71 species identified from both depths, with 45 species overlapping (63.0%). The percent cover of sponges surveyed at altiphotic reefs accounted for 9.0% (±1.04 SE), while the percent cover of sponges surveyed at mesophotic reefs was 14.0% (±1.96 SE). Our data show fish, coral, and sponge assemblages are differentiated between 20 and 45 m along the Guánica shelf edge offshore of the Guánica Biosphere Reserve. This study represents the first observations for species distributions of adjacent altiphotic and mesophotic coral reef habitats along the Guánica shelf edge, as well as provides an annotated species list of the local sponge fauna. Combined, these results highlight the need for continued environmental stewardship and conservation in the area.
