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Journal articles on the topic 'Estuarine habitats'
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1
Bissoli, Lorena B., and Angelo F. Bernardino. "Benthic macrofaunal structure and secondary production in tropical estuaries on the Eastern Marine Ecoregion of Brazil." PeerJ 6 (February 28, 2018): e4441. http://dx.doi.org/10.7717/peerj.4441.
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Tropical estuaries are highly productive and support diverse benthic assemblages within mangroves and tidal flats habitats. Determining differences and similarities of benthic assemblages within estuarine habitats and between regional ecosystems may provide scientific support for management of those ecosystems. Here we studied three tropical estuaries in the Eastern Marine Ecoregion of Brazil to assess the spatial variability of benthic assemblages from vegetated (mangroves) and unvegetated (tidal flats) habitats. A nested sampling design was used to determine spatial scales of variability in benthic macrofaunal density, biomass and secondary production. Habitat differences in benthic assemblage composition were evident, with mangrove forests being dominated by annelids (Oligochaeta and Capitellidae) whereas peracarid crustaceans were also abundant on tidal flats. Macrofaunal biomass, density and secondary production also differed between habitats and among estuaries. Those differences were related both to the composition of benthic assemblages and to random spatial variability, underscoring the importance of hierarchical sampling in estuarine ecological studies. Given variable levels of human impacts and predicted climate change effects on tropical estuarine assemblages in Eastern Brazil, our data support the use of benthic secondary production to address long-term changes and improved management of estuaries in Eastern Brazil.
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Henderson, Christopher J., Ben L. Gilby, Thomas A. Schlacher, Rod M. Connolly, Marcus Sheaves, Nicole Flint, Hayden P. Borland, and Andrew D. Olds. "Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes." ICES Journal of Marine Science 76, no. 4 (February 4, 2019): 1052–61. http://dx.doi.org/10.1093/icesjms/fsz007.
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Abstract Coastal seascapes are composed of a diversity of habitats that are linked in space and time by the movement of organisms. The context and configuration of coastal ecosystems shapes many important properties of animal assemblages, but potential seascape effects of natural and artificial habitats on nearby habitats are typically considered in isolation. We test whether, and how, the seascape context of natural and urban habitats modified fish assemblages across estuaries. Fish were sampled with underwater videos in five habitat types (mangroves, rock bars, log snags, unvegetated sediments, armoured shorelines) in 17 estuaries in eastern Australia. Different habitats supported distinct fish assemblages, but the spatial context of mangroves and armoured shorelines had pervasive ecological effects that extended across entire estuaries. In most estuarine habitats, fish diversity and abundance was greatest when they were in close proximity of mangroves, and decreased due to the proximity of armoured shorelines. Many cities are centred on estuaries, and urban expansion is often associated with the fragmentation of mangrove forests. Our findings emphasize that these transformations of urban estuarine landscapes are likely to propagate to broader ecological impacts detectable in multiple habitats beyond mangrove forests.
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Murray, Taryn S., Paul D. Cowley, Rhett H. Bennett, and Amber-Robyn Childs. "Fish on the move: connectivity of an estuary-dependent fishery species evaluated using a large-scale acoustic telemetry array." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 11 (November 2018): 2038–52. http://dx.doi.org/10.1139/cjfas-2017-0361.
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Connectivity — movements of animals between and among numerous habitats — and the factors (rhythmic cycles and environmental variables) influencing connectivity of juvenile Lichia amia (Teleostei: Carangidae) were assessed in complementary acoustic telemetry studies in two geographically separated estuaries (620 km apart) in South Africa. The studies were conducted within a nationwide array of acoustic receivers moored in estuaries and coastal waters. Tagged fish in both the Kowie (n = 21) and Goukou (n = 17) estuaries displayed high levels of multiple habitat connectivity, with 81% and 76% visiting nearby marine and estuarine environments, respectively. The presence of tagged L. amia within the tagging estuaries was significantly influenced by river and sea temperature (Kowie) and river inflow and moon phase (Goukou). Tidal phase, time of day, and season were found to significantly influence marine excursions undertaken by Kowie- and Goukou-tagged fish. Our study provides an assessment of connectivity among multiple estuarine, port, and marine habitats, relating those movements to rhythmic cycles and environmental variables, and highlights the benefits of tracking animals using an extensive acoustic receiver array that spans multiple habitats.
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Pita, Ana Laura, Luis Giménez, Noelia Kandratavicius, Pablo Muniz, and Natalia Venturini. "Benthic trophic status of aquatic transitional environments with distinct morphological and dynamic characteristics on the south-western Atlantic coast." Marine and Freshwater Research 68, no. 11 (2017): 2028. http://dx.doi.org/10.1071/mf16284.
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The benthic trophic status of Uruguayan coastal estuarine habitats (permanently open estuaries and open or closed coastal lagoons) was evaluated, twice in 1 year and at different spatial scales, using the amount and biochemical composition of the sedimentary organic matter. Nested hierarchical ANOVAs were applied to evaluate differences at the habitat level, among sites for each type of estuarine habitat (three estuaries and three lagoons) and between sectors located at different distances from the sea (inner v. outer sectors). Morphological and hydrodynamic differences between the two types of habitats explained site-to-site variations in eutrophic conditions in the open or closed coastal lagoons and meso-oligotrophic conditions in permanently open estuaries. These differences followed the patterns found for sediment grain size, with inner sectors (lower-energy areas) favouring the accumulation of finer sediments and higher amounts of degraded–detrital organic matter. In autumn, biochemical parameters indicated the dominance of aged and more degraded organic matter, with both types of habitats having a low nutritional value no matter which sector was considered. By contrast, in spring, biochemical composition showed the prevalence of fresh and more labile sedimentary organic matter with a high food value, especially in the outer sectors.
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Taylor, Matthew D. "Spatial and temporal patterns of habitat use by three estuarine species of mysid shrimp." Marine and Freshwater Research 59, no. 9 (2008): 792. http://dx.doi.org/10.1071/mf07247.
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The mysids Rhopalopthalmus egregius, Haplostylus dakini and Doxomysis australiensis are abundant yet unstudied omnivorous crustaceans in Australian estuaries. Habitat use and population dynamics were investigated for these species over spring and summer in the Tweed River, Australia, to explore their ecological role in estuarine ecosystems. Overall, mysids were concentrated in shallow unvegetated and deep unvegetated estuarine habitats. H. dakini were most abundant in shallow and deep bare habitats at night, whereas R. egregius were most abundant in deep bare habitats during the night. D. australiensis were present across all habitats in the night, but negligible numbers were present during the day. Significantly greater numbers of R. egregius and D. australiensis were sampled during the new moon, compared with the full moon. Significantly larger R. egregius and D. australiensis individuals were present in benthic habitats at night, indicating possible partitioning of habitat for juvenile and adult subpopulations. Adaptive foraging strategies and habitat use facilitates the coexistence of sympatric mysid species, H. dakini and R. egregius, and within-species habitat partitioning allowed juvenile R. egregius to avoid interaction with adult R. egregius. The observed dynamics minimize inter- and intra-specific predation between mysids, and by other predators, while optimizing access to key trophic resources.
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Hughes, Brent B., Kerstin Wasson, M. Tim Tinker, Susan L. Williams, Lilian P. Carswell, Katharyn E. Boyer, Michael W. Beck, et al. "Species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries." PeerJ 7 (December 10, 2019): e8100. http://dx.doi.org/10.7717/peerj.8100.
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Recovering species are often limited to much smaller areas than they historically occupied. Conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. Southern sea otters (Enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the California outer coast, where most of their recovery has occurred. However, studies of recently-recolonized estuaries have revealed that estuaries can provide southern sea otters with high quality habitats featuring shallow waters, high production and ample food, limited predators, and protected haul-out opportunities. Moreover, sea otters can have strong effects on estuarine ecosystems, fostering seagrass resilience through their consumption of invertebrate prey. Using a combination of literature reviews, population modeling, and prey surveys we explored the former estuarine habitats outside the current southern sea otter range to determine if these estuarine habitats can support healthy sea otter populations. We found the majority of studies and conservation efforts have focused on populations in exposed, rocky coastal habitats. Yet historical evidence indicates that sea otters were also formerly ubiquitous in estuaries. Our habitat-specific population growth model for California’s largest estuary—San Francisco Bay—determined that it alone can support about 6,600 sea otters, more than double the 2018 California population. Prey surveys in estuaries currently with (Elkhorn Slough and Morro Bay) and without (San Francisco Bay and Drakes Estero) sea otters indicated that the availability of prey, especially crabs, is sufficient to support healthy sea otter populations. Combining historical evidence with our results, we show that conservation practitioners could consider former estuarine habitats as targets for sea otter and ecosystem restoration. This study reveals the importance of understanding how recovering species interact with all the ecosystems they historically occupied, both for improved conservation of the recovering species and for successful restoration of ecosystem functions and processes.
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Bernardino, Angelo Fraga, Paulo Roberto Pagliosa, Ronaldo Adriano Christofoletti, Francisco Barros, Sergio A. Netto, Pablo Muniz, and Paulo da Cunha Lana. "Benthic estuarine communities in Brazil: moving forward to long term studies to assess climate change impacts." Brazilian Journal of Oceanography 64, spe2 (2016): 81–96. http://dx.doi.org/10.1590/s1679-875920160849064sp2.
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Abstract Estuaries are unique coastal ecosystems that sustain and provide essential ecological services for mankind. Estuarine ecosystems include a variety of habitats with their own sediment-fauna dynamics, all of them globally undergoing alteration or threatened by human activities. Mangrove forests, saltmarshes, tidal flats and other confined estuarine systems are under increasing stress due to human activities leading to habitat and species loss. Combined changes in estuarine hydromorphology and in climate pose severe threats to estuarine ecosystems on a global scale. The ReBentos network is the first integrated attempt in Brazil to monitor estuarine changes in the long term to detect and assess the effects of global warming. This paper is an initial effort of ReBentos to review current knowledge on benthic estuarine ecology in Brazil. We herein present and synthesize all published work on Brazilian estuaries that has focused on the description of benthic communities and related ecological processes. We then use current data on Brazilian estuaries and present recommendations for future studies to address climate change effects, suggesting trends for possible future research and stressing the need for long-term datasets and international partnerships.
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Whitfield, AK. "Littoral habitats as major nursery areas for fish species in estuaries: a reinforcement of the reduced predation paradigm." Marine Ecology Progress Series 649 (September 10, 2020): 219–34. http://dx.doi.org/10.3354/meps13459.
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For many decades, the role of estuaries as important nursery areas for fishes was accepted as fact by scientists and environmental managers. At the turn of the 21st century, a question mark was raised in relation to the reduced predation component of the nursery function, with some scientists contending that both large and small piscivorous fish species had access to the estuarine habitats that juvenile fishes in estuaries occupied. If true on a global scale, the nursery designation for these habitats would be compromised and the long-held paradigm that estuaries are important nursery areas for fishes would need to be revised. In this review, I examine the nature of fish nursery areas in estuarine littoral habitats from a mainly predation perspective and, based on a variety of ichthyofaunal and avifaunal studies, come to the conclusion that apart from a few selected estuarine systems, there is limited predation on juvenile fishes in these particular areas. This, coupled with the abundant suitable food resources for juvenile fish from different trophic categories, shelter from high-energy marine wave action and biological connectivity between a variety of submerged and emergent macrophyte communities, renders shallow estuarine littoral areas ideal nursery areas for the juveniles of mostly euryhaline marine fish species, the dominant component of estuarine ichthyofaunas globally. In addition, there are strong indications from the fossil record that these littoral estuarine nursery areas have been functioning since the Devonian, more than 350 million years ago.
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Werry, J. M., S. Y. Lee, N. M. Otway, Y. Hu, and W. Sumpton. "A multi-faceted approach for quantifying the estuarine - nearshore transition in the life cycle of the bull shark, Carcharhinus leucas." Marine and Freshwater Research 62, no. 12 (2011): 1421. http://dx.doi.org/10.1071/mf11136.
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Understanding the ontogenetic habitat linkages of sharks is important for conservation and managing human interactions. We used acoustic telemetry, catch data, elemental and stable isotope signatures and dietary analyses to investigate ontogenetic habitat use in south-east Queensland, Australia, by the bull shark Carcharhinus leucas, a IUCN ‘near-threatened’ species that is implicated in many shark attacks on humans in urban estuaries. Sequential analyses for δ15N and δ13C of vertebrae from five adult C. leucas and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for elemental composition from 23 C. leucas, including a pregnant female, were also used to trace ontogenetic habitat dependence. Acoustic telemetry indicated large juvenile and subadult C. leucas remained in estuarine habitats. δ15N values across shark vertebrae showed an ontogenetic shift in diet with total length (TL), confirmed by stomach contents. LA-ICPMS data reflected the ontogenetic movements of C. leucas from natal habitats. Differences among adults were gender related. Shifts in habitat use by subadults were correlated with a sigmoidal δ13C relationship with TL. C. leucas have a multipartite, stage-specific dependency in their transition between habitats along the freshwater–estuarine–marine continuum, making them particularly susceptible to the habitat alteration that is occurring globally.
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Meynecke, J. O. "Coastal habitat connectivity ? implications for declared fish habitat networks in Queensland, Australia." Pacific Conservation Biology 15, no. 2 (2009): 96. http://dx.doi.org/10.1071/pc090096.
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Estuaries are widely recognized as key habitats supporting nearshore secondary production and catch of commercial fisheries. In Queensland, some of these coastal marine habitats are protected by the declared fish habitat programme run by the Department of Primary Industries and Fisheries. Expected environmental changes for Australian estuarine systems include reduced freshwater flow, increased sedimentation and with them, a loss of connectivity. At present, the relationship between the protected declared fish habitat and habitat connectivity remains unknown. By comparing long term coastal fish catch data with geomorphic characteristics of coastal habitats structural connectivity was previously identified as a potential driver of commercial fish catch in Queensland. An ecology landscape approach was used for this study to identify potential fish habitat hotspots along the coastline of Queensland thus allowing better defined networks of declared fish habitats. A comparison between this approach and the current declared fish habitats demonstrated potential deficits and provided important insights for fisheries management. Declared fish habitats should be placed in coastal habitats with high structural connectivity to ensure sustainability of fisheries in light of environmental changes.
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Kennish, Michael J. "Environmental threats and environmental future of estuaries." Environmental Conservation 29, no. 1 (March 2002): 78–107. http://dx.doi.org/10.1017/s0376892902000061.
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Estuaries exhibit a wide array of human impacts that can compromise their ecological integrity, because of rapid population growth and uncontrolled development in many coastal regions worldwide. Long-term environmental problems plaguing estuaries require remedial actions to improve the viability and health of these valuable coastal systems. Detailed examination of the effects of pollution inputs, the loss and alteration of estuarine habitat, and the role of other anthropogenic stress indicates that water quality in estuaries, particularly urbanized systems, is often compromised by the overloading of nutrients and organic matter, the influx of pathogens, and the accumulation of chemical contaminants. In addition, the destruction of fringing wetlands and the loss and alteration of estuarine habitats usually degrade biotic communities. Estuaries are characterized by high population densities of microbes, plankton, benthic flora and fauna, and nekton; however, these organisms tend to be highly vulnerable to human activities in coastal watersheds and adjoining embayments. Trends suggest that by 2025 estuaries will be most significantly impacted by habitat loss and alteration associated with a burgeoning coastal population, which is expected to approach six billion people. Habitat destruction has far reaching ecological consequences, modifying the structure, function, and controls of estuarine ecosystems and contributing to the decline of biodiversity. Other anticipated high priority problems are excessive nutrient and sewage inputs to estuaries, principally from land-based sources. These inputs will lead to the greater incidence of eutrophication as well as hypoxia and anoxia. During the next 25 years, overfishing is expected to become a more pervasive and significant anthropogenic factor, also capable of mediating global-scale change to estuaries. Chemical contaminants, notably synthetic organic compounds, will remain a serious problem, especially in heavily industrialized areas. Freshwater diversions appear to be an emerging global problem as the expanding coastal population places greater demands on limited freshwater supplies for agricultural, domestic, and industrial needs. Altered freshwater flows could significantly affect nutrient loads, biotic community structure, and the trophodynamics of estuarine systems. Ecological impacts that will be less threatening, but still damaging, are those caused by introduced species, sea level rise, coastal subsidence, and debris/litter. Although all of these disturbances can alter habitats and contribute to shifts in the composition of estuarine biotic communities, the overall effect will be partial changes to these ecosystem components. Several strategies may mitigate future impacts.
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Roberts, Christine, Oluna Ceska, Paul Kroeger, and Bryce Kendrick. "Macrofungi from six habitats over five years in Clayoquot Sound, Vancouver Island." Canadian Journal of Botany 82, no. 10 (October 1, 2004): 1518–38. http://dx.doi.org/10.1139/b04-114.
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Over 5 years, macrofungi from six habitats in Clayoquot Sound, Vancouver Island, British Columbia, were documented. Habitats were categorized as dune, spruce fringe, old-growth rainforest, second-growth forest, bog, or estuarine. All but the second-growth forest are natural ecosystems. A total of 551 taxa of macrofungi were recorded. Between 17% and 36% of the species in any one habitat were found only in that habitat. The most frequently encountered and ubiquitous species was Craterellus tubaeformis (Fr.) Quel., found in all years, habitats, and sites. Of the 551 taxa, only 28 were found every year, and 308 were found in only 1 year. Rare species that were recorded include Cordyceps ravenelii Berkeley & Curtis, Hygrophorus inocybiformis Smith, and Tricholoma apium Schaeffer in the dunes and Stereopsis humphreyi (Burt) Redhead in the spruce fringe. Similarities between habitats based on taxa in common showed that bog and estuarine habitats had only 9%17% in common with each other and the other habitats, whereas dune, spruce fringe, and the two forest types shared 21%31% of their species. Old-growth rainforest yielded approximately 4 times as many species as bog and estuarine habitats, and approximately 1.5 times as many as the other three habitats.Key words: Clayoquot Sound, Vancouver Island, macrofungi, habitats, biodiversity.
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Henderson, Christopher J., Ben L. Gilby, Edward Stone, Hayden P. Borland, and Andrew D. Olds. "Seascape heterogeneity modifies estuarine fish assemblages in mangrove forests." ICES Journal of Marine Science 78, no. 3 (February 12, 2021): 1108–16. http://dx.doi.org/10.1093/icesjms/fsab022.
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Abstract Mangroves are a dominant structural habitat within tropical and subtropical estuaries that provide a number of ecosystem services, including habitat for a range of crustaceans and fish. However, mangroves are one of the most threatened estuarine habitats globally, having been severely reduced in extent, and replaced by urban structures. Here, we test for the effects of both natural (e.g. seagrass, rock and mangroves habitat extent, and connectivity) and human (e.g. extent of urban area) landscape variables on the number and type of fish inhabiting mangroves forests. We used remote underwater video stations to quantify fish assemblages within mangroves at 150 sites in 30 estuaries across Queensland, Australia. Fish community structure was best explained by the extent of mangroves and seagrasses within an estuary, the distance to the estuary mouth, and the size of the estuary and catchment. Moderate catchment size and proximity to the estuary mouth increased species richness and abundance of harvestable fish at individual mangrove sites. In order to maintain mangrove fish assemblages and the functions they provide, management initiatives should focus on maintaining natural estuarine seascapes that are located closer to the mouth of estuaries, in particular, focusing on estuaries that have lower levels of catchment urbanization.
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Watts, Robyn J., and Michael S. Johnson. "Estuaries, lagoons and enclosed embayments: habitats that enhance population subdivision of inshore fishes." Marine and Freshwater Research 55, no. 7 (2004): 641. http://dx.doi.org/10.1071/mf04051.
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Several studies have suggested that estuaries, lagoons and enclosed embayments may offer special opportunities for local subdivision in marine species. We used data from published papers and unpublished theses to examine the effect of such water bodies on allozyme differentiation of seven species of inshore fishes in Western Australia. We included species that differ in their dispersal, and hence their intrinsic potential for gene flow. Over large distances, subdivision was generally greater among estuarine populations than among conspecific marine populations collected over similar distances. Over small distances, paired marine and estuarine samples were generally more divergent than pairs of marine samples separated by similar distances. For species with a low capability for dispersal, estuaries appear to add to the high levels of genetic subdivision that commonly result from other factors. Under special circumstances estuaries may also provide opportunities for genetic divergence in species with a high capability of dispersal that are rarely subdivided at a large geographical scale. These observations indicate that estuaries can increase the genetic subdivision of populations of inshore fishes, and that species that use both marine and estuarine habitats are likely to have greater genetic subdivision than those that are restricted to marine habitats.
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DiGiacomo, Alexandra E., Walker E. Harrison, David W. Johnston, and Justin T. Ridge. "Elasmobranch Use of Nearshore Estuarine Habitats Responds to Fine-Scale, Intra-Seasonal Environmental Variation: Observing Coastal Shark Density in a Temperate Estuary Utilizing Unoccupied Aircraft Systems (UAS)." Drones 4, no. 4 (December 8, 2020): 74. http://dx.doi.org/10.3390/drones4040074.
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Many coastal shark species are known to use estuaries of the coastal southeastern United States for essential purposes like foraging, reproducing, and protection from predation. Temperate estuarine landscapes, such as the Rachel Carson Reserve (RCR) in Beaufort, NC, are dynamic habitat mosaics that experience fluctuations in physical and chemical oceanographic properties on various temporal and spatial scales. These patterns in abiotic conditions play an important role in determining species movement. The goal of this study was to understand the impact of environmental conditions around the RCR on shark density within the high-abundance summer season. Unoccupied Aircraft System (UAS) surveys of coastal habitats within the reserve were used to quantify shark density across varying environmental conditions. A combination of correlation analyses and Generalized Linear Modelling (GLM) revealed that density differs substantially across study sites and increases with rising water temperatures, conclusions that are supported by previous work in similar habitats. Additionally, density appears to increase moving towards dawn and dusk, potentially supporting crepuscular activity in coastal estuarine areas. By describing shark density dynamics in the RCR, this study provides new information on this population and presents a novel framework for studying elasmobranchs in temperate estuaries.
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Adams, Aaron J., and R. Kirby Wolfe. "Occurrence and persistence of non-native Cichlasoma urophthalmus (family Cichlidae) in estuarine habitats of south-west Florida (USA): environmental controls and movement patterns." Marine and Freshwater Research 58, no. 10 (2007): 921. http://dx.doi.org/10.1071/mf07086.
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The geographic scope of species introductions has increased dramatically in the last 200 years. One of the greatest challenges to understanding the ecological consequences of non-native species is that it has been difficult to identify the attributes that allow them to become established outside their native range. This challenge is compounded by anthropogenic habitat alteration that often enhances the establishment and expansion of non-native species. Fishes in the family Cichlidae are notoriously adaptive, and contribute more non-native species to North America than any other fish family. This is especially true in Florida (USA), where 18 cichlid species have become established. The Mayan cichlid (Cichlasoma urophthalmus) was first documented in south Florida in 1983, and is present in many freshwater and estuarine habitats. This study reports a northward range expansion by C. urophthalmus, demonstrates the connectivity between altered freshwater habitats and tidal estuarine habitats, and suggests that the estuarine populations are ephemeral and dependent upon colonisation from populations in altered freshwater habitats.
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Hicks, Andy, Nicole C. Barbee, Stephen E. Swearer, and Barbara J. Downes. "Estuarine geomorphology and low salinity requirement for fertilisation influence spawning site location in the diadromous fish, Galaxias maculatus." Marine and Freshwater Research 61, no. 11 (2010): 1252. http://dx.doi.org/10.1071/mf10011.
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In habitats such as estuaries, which are characterised by large and fluctuating gradients in abiotic variables, finding appropriate habitat for successful spawning and egg development can be critical to a species’ survival. We explored how salinity requirements for successful fertilisation may govern the distribution of estuarine spawning habitat for the diadromous fish, Galaxias maculatus, which spawns in inundated vegetation on estuary banks during spring tides. Artificial fertilisation experiments confirmed that successful fertilisation only occurs at low salinities (<20). Thus, we predicted that egg distributions would depend upon the extent of low-salinity surface waters in an estuary. Using estuary geomorphology classification schemes, which classify estuaries by physical and chemical characteristics such as their salinity dynamics, we hypothesised that stratified estuaries would provide a greater extent of low salinity surface water than well-mixed estuaries. This prediction was supported by surveys of egg distributions in five estuaries in Victoria, Australia. Eggs were distributed over a greater proportion of ‘stratified’ v. ‘mixed’ estuary types. We suggest that combining knowledge of the spawning requirements of a species and physical properties of the habitat, such as those encapsulated in estuary geomorphic classification schemes, can greatly facilitate efforts to identify critical habitats and thus aid in species management and conservation.
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Muething, KA, F. Tomas, G. Waldbusser, and BR Dumbauld. "On the edge: assessing fish habitat use across the boundary between Pacific oyster aquaculture and eelgrass in Willapa Bay, Washington, USA." Aquaculture Environment Interactions 12 (December 3, 2020): 541–57. http://dx.doi.org/10.3354/aei00381.
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Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as ‘essential fish habitat’, restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.
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Coleman, M. A., J. S. Clark, M. A. Doblin, M. J. Bishop, and B. P. Kelaher. "Genetic differentiation between estuarine and open coast ecotypes of a dominant ecosystem engineer." Marine and Freshwater Research 70, no. 7 (2019): 977. http://dx.doi.org/10.1071/mf17392.
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Temperate intertidal shores globally are often dominated by habitat-forming seaweeds, but our knowledge of these systems is heavily biased towards northern hemisphere species. Rocky intertidal shores throughout Australia and New Zealand are dominated by a single monotypic species, Hormosira banksii. This species plays a key role in facilitating biodiversity on both rocky shores and estuarine habitats, yet we know little about the processes that structure populations. Herein we characterise the genetic diversity and structure of Hormosira and demonstrate strong restrictions to gene flow over small spatial scales, as well as between estuarine and open coast populations. Estuarine ecotypes were often genetically unique from nearby open coast populations, possibly due to extant reduced gene flow between habitats, founder effects and coastal geomorphology. Deviations from random mating in many locations suggest complex demographic processes are at play within shores, including clonality in estuarine populations. Strong isolation by distance in Hormosira suggests that spatial management of intertidal habitats will necessitate a network of broad-scale protection. Understanding patterns of genetic diversity and gene flow in this important ecosystem engineer will enhance the ability to manage, conserve and restore this key species into the future.
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Carle, Melissa Vernon, Kristopher G. Benson, and James F. Reinhardt. "Quantifying the Benefits of Estuarine Habitat Restoration in the Gulf of Mexico: an Introduction to the Theme Section." Estuaries and Coasts 43, no. 7 (July 31, 2020): 1680–91. http://dx.doi.org/10.1007/s12237-020-00807-z.
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Abstract This collection of papers provides insights into methods and data currently available to quantify the benefits associated with estuarine habitat restoration projects in the northern Gulf of Mexico, USA, with potential applicability to other coastal systems. Extensive habitat restoration is expected to occur in the northern Gulf of Mexico region over the next several decades through funding associated with the 2010 Deepwater Horizon oil spill. Papers in this section examine the development of vegetation, soil properties, invertebrate fauna, and nekton communities in restored coastal marshes and provide a conceptual framework for applying these findings to quantify the benefits associated with compensatory marsh restoration. Extensive meta-analysis of existing data for Gulf of Mexico coastal habitats further confirms that structured habitats such as marsh, submerged aquatic vegetation, and oyster reefs support greater nekton densities than nonvegetated bottom habitat, with oyster reefs supporting different species assemblages than marsh and submerged aquatic vegetation. Other papers demonstrate that while vegetation cover can establish rapidly within the first 5 years of restoration, belowground parameters such as root biomass and soil organic matter remain 44% to 92% lower at restored marshes than reference marshes 15 years after restoration. On average, amphipod and nekton densities are also not fully restored until at least 20 and 13 years following restoration, respectively. Additional papers present methods to estimate the benefits associated with marsh restoration projects, nekton productivity associated with coastal and estuarine habitats, and the benefits associated with the removal of derelict crab traps in Gulf of Mexico estuaries.
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Pontee, N. I. "Designing sustainable estuarine intertidal habitats." Proceedings of the Institution of Civil Engineers - Engineering Sustainability 156, no. 3 (September 2003): 157–67. http://dx.doi.org/10.1680/ensu.2003.156.3.157.
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Pontee, N. I. "Designing sustainable estuarine intertidal habitats." Engineering Sustainability 156, no. 3 (September 2003): 157–67. http://dx.doi.org/10.1680/ensu.156.3.157.36969.
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Bolzan, Michelle Sequine, Ryan Andrades, Henry Louis Spach, and Mauricio Hostim-Silva. "The influence of selected environmental parameters and habitat mosaics on fish assemblages in a South American estuary." Journal of the Marine Biological Association of the United Kingdom 99, no. 1 (February 13, 2018): 249–57. http://dx.doi.org/10.1017/s0025315418000012.
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Coastal environments are faced with constant habitat modification and biodiversity loss due to human occupation. Estuaries are considered to be highly productive and shelter heterogeneous habitats such as mangrove forests, tidal creeks, tidal mud flats and sandy beaches, which are important for the maintenance of natural resources. The present study aims to evaluate how different shallow juvenile habitats (sandy beaches, mangrove shoreline habitats and dense macrophyte habitats) influence fish during their early life stages in a tropical estuary of Brazil. Monthly samples using a beach seine net from July 2012 to June 2013 were collected in eight shallow areas of the São Mateus River estuary. The fish assemblage comprised mainly juvenile and small-sized fish, which included ecologically and commercially important species. Small recruits of Atherinella brasiliensis and Ctenogobius boleosoma were most abundant in the autumn, while Rhinosardinia bahiensis and Centropomus undecimalis were highly abundant during the winter. The water salinity recorded in the mid and lower estuarine portions was the most important variable for the distribution of A. brasiliensis and Sphoeroides spengleri, whereas Anchovia clupeoides, C. undecimalis, C. parallelus and Gobionellus oceanicus were positively correlated with the water depth of the upper estuarine portion. The fish species T. paulistanus, Genidens genidens and Achirus lineatus were related to the water turbidity in the upper portion. Thus, the heterogeneous shallow water habitats (and their associated environmental parameters) of the São Mateus River estuary are potential nursery grounds for the early life stages of a variety of fish species, which highlights the importance of these areas for local biodiversity management.
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Arifianti, Eka Nur, Husain Latuconsina, and Hasan Zayadi. "Composition and Density of Gastropode in Mangrove Habitat of Banyuurip, Ujung Pangkah - Gresik." Agrikan: Jurnal Agribisnis Perikanan 14, no. 1 (April 4, 2021): 65–72. http://dx.doi.org/10.29239/j.agrikan.14.1.65-72.
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Gastropods are one of the biota that live in association with mangrove habitat. This study aims to compare the species composition and structure of the gastropod community in different mangrove habitats. This research was conducted in Banyuurip Mangrove Center (BMC), Ujung Pangkah-Gresik during July-August 2020. Determination of the observation station purposively based on physical differences in mangrove habitat. Estimation of mangrove and gastrode density by systematic sampling method using belt transects. There were 12 mangrove species with the highest number of species in the coastal mangrove habitat, with the highest species composition and density of Avicennia marina. The highest mangrove density was found in coastal mangrove habitats for all criteria. The number of gastropods found were 2,171 specimens belonging to 15 species, 5 families and 5 orders. The highest number of species, families and orders in coastal mangrove habitat were 1,191 specimens, 11 species from 5 families and 5 orders, the lowest was in estuarine mangrove habitat as many as 980 specimens from 9 species, 2 families and 2 orders. Densities of gastropods differ between mangrove habitats, with the highest density in coastal mangrove habitats and the lowest in estuarine mangrove habitats. The composition and density of the highest gastropods species in the estuary mangrove habitat is Cassidula aurisfelis and in the coastal mangrove habitat is Pirenella cingulata. The importance of conservation and rehabilitation efforts for mangroves that have been degraded to support the gastropods associated in it.
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Hollweg, Terill A., Mary C. Christman, Just Cebrian, Bryan P. Wallace, Scott L. Friedman, Heather R. Ballestero, Mary T. Huisenga, and Kristopher G. Benson. "Meta-analysis of Nekton Utilization of Coastal Habitats in the Northern Gulf of Mexico." Estuaries and Coasts 43, no. 7 (October 29, 2019): 1722–45. http://dx.doi.org/10.1007/s12237-019-00633-y.
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Abstract Estuaries in the northern Gulf of Mexico (GOM) provide habitat for many ecologically, commercially, and recreationally important fish and crustacean species (i.e., nekton), but patterns of nekton abundance and community assemblages across habitat types, salinity zones, and seasons have not been described region-wide. Recognizing the wealth of information collected from previous and ongoing field sampling efforts, we developed a meta-analytical approach to aggregate nekton density data from separate studies (using different gear types) that can be used to answer key research questions. We then applied this meta-analytical approach to separate nekton datasets from studies conducted in the Gulf of Mexico to summarize patterns in nekton density across and within several estuarine habitat types, including marsh, oyster reefs, submerged aquatic vegetation (SAV), and open-water non-vegetated bottom (NVB). The results of the meta-analysis highlighted several important patterns of nekton use associated with these habitat types. Nekton densities were higher in structured estuarine habitats (i.e., marsh, oyster reefs, SAV) than in open-water NVB habitat. Marsh and SAV community assemblages were relatively similar to each other, but different from those associated with open-water NVB and oyster habitats. Densities of commercially and recreationally important crustacean and fish species were highest in saline marshes, thus demonstrating the importance of this habitat in the northern GOM. The results of our meta-analysis are generally consistent with previous site-specific studies in the region (many of which were included in the meta-analysis) and provide further evidence for these patterns at a regional scale. This meta-analytical approach is easy to implement for diverse research and management purposes, and provides the opportunity to advance understanding of the value and role of coastal habitats to nekton communities.
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Veldkornet, D. A., J. B. Adams, J. S. Boatwright, and A. Rajkaran. "Barcoding of estuarine macrophytes and phylogenetic diversity of estuaries along the South African coastline." Genome 62, no. 9 (September 2019): 585–95. http://dx.doi.org/10.1139/gen-2018-0067.
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Plant DNA barcoding serves as an effective approach to building community phylogenies and increasing our understanding of the factors that determine plant community assemblages. The aims of the study were to (i) barcode macrophytes with high estuarine fidelity and (ii) to determine the phylogenetic diversity (PD) of selected South African estuaries for conservation prioritisation. Three DNA barcoding gene regions (rbcLa, matK, and trnH-psbA) were assessed, and community phylogenies were constructed for 270 estuaries. Generally, the matK barcode had the greatest discrimination success rate of 67.4% (parsimony informative sites = 418). Closely related species formed clades that also represent estuarine habitat types. Estuaries with high phylogenetic diversity along the southeast coast were associated with a combination of mangrove and salt marsh habitats. Species richness was strongly and significantly correlated with PD (r = 0.93; p < 0.000). Based on mean pairwise distance (MPD), more temperate estuaries (56) showed significant phylogenetic clustering compared to subtropical estuaries (24) (p < 0.05). Similarly, based on mean nearest taxon distance (MNTD), significant phylogenetic clustering was highest in temperate estuaries (50) compared to subtropical estuaries (12) (p < 0.05). This suggests that the coexistence of plant species in estuaries is structured by both biotic and abiotic interactions.
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Davis, Tom R., David Harasti, and Stephen D. A. Smith. "Developing a habitat classification typology for subtidal habitats in a temperate estuary in New South Wales, Australia." Marine and Freshwater Research 67, no. 8 (2016): 1186. http://dx.doi.org/10.1071/mf15123.
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Effective estuarine management depends on adequate data about the ecology, extent and biodiversity of component habitats. However, these data are often scant, as exemplified by the Port Stephens estuary, part of the Port Stephens–Great Lakes Marine Park (NSW, Australia), for which even basic descriptions of habitat types and extent are lacking. Herein we present the results of the first quantitative assessment of subtidal benthic communities within the estuary, involving 130km of towed video transects over an area exceeding 50km2. We identified previously undocumented macroalgae-dominated habitat types and found strong correlations between habitat types and depth. The soft coral Dendronephthya australis habitat is of particular interest because this was found to occur exclusively outside current sanctuary (no take) zones. The habitat map of Port Stephens generated during the study provides the basis for more objective representative planning in future iterations of zoning in the estuarine section of the marine park. The study also suggests that depth may be a useful proxy for estuarine habitat types where specific data are lacking. The classification methodology developed during the study was cost-effective, generated robust data and consequently has potential for wider application in other large estuarine bays.
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Pacella, Stephen R., Cheryl A. Brown, George G. Waldbusser, Rochelle G. Labiosa, and Burke Hales. "Seagrass habitat metabolism increases short-term extremes and long-term offset of CO2 under future ocean acidification." Proceedings of the National Academy of Sciences 115, no. 15 (April 2, 2018): 3870–75. http://dx.doi.org/10.1073/pnas.1703445115.
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The role of rising atmospheric CO2 in modulating estuarine carbonate system dynamics remains poorly characterized, likely due to myriad processes driving the complex chemistry in these habitats. We reconstructed the full carbonate system of an estuarine seagrass habitat for a summer period of 2.5 months utilizing a combination of time-series observations and mechanistic modeling, and quantified the roles of aerobic metabolism, mixing, and gas exchange in the observed dynamics. The anthropogenic CO2 burden in the habitat was estimated for the years 1765–2100 to quantify changes in observed high-frequency carbonate chemistry dynamics. The addition of anthropogenic CO2 alters the thermodynamic buffer factors (e.g., the Revelle factor) of the carbonate system, decreasing the seagrass habitat’s ability to buffer natural carbonate system fluctuations. As a result, the most harmful carbonate system indices for many estuarine organisms [minimum pHT, minimum Ωarag, and maximum pCO2(s.w.)] change up to 1.8×, 2.3×, and 1.5× more rapidly than the medians for each parameter, respectively. In this system, the relative benefits of the seagrass habitat in locally mitigating ocean acidification increase with the higher atmospheric CO2 levels predicted toward 2100. Presently, however, these mitigating effects are mixed due to intense diel cycling of CO2 driven by aerobic metabolism. This study provides estimates of how high-frequency pHT, Ωarag, and pCO2(s.w.) dynamics are altered by rising atmospheric CO2 in an estuarine habitat, and highlights nonlinear responses of coastal carbonate parameters to ocean acidification relevant for water quality management.
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Whitfield, A. "Predation on small juvenile fishes in shallow estuarine nursery areas: Reply to Baker & Sheaves (2021)." Marine Ecology Progress Series 662 (March 18, 2021): 209–14. http://dx.doi.org/10.3354/meps13678.
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The key criticism by Baker & Sheaves (2021; Mar Ecol Prog Ser 662:205-208) of the Whitfield (2020; Mar Ecol Prog Ser 649:219-234) estuarine littoral predation paradigm review is that shallow water fish nursery habitats contain abundant predator assemblages which may create high predation pressure on the juvenile fish cohorts that occupy these areas. The primary arguments supporting Baker & Sheaves’ criticism arise from a series of papers published by them on piscivorous fish predation in certain tropical Australian estuaries. The counter-argument that shallow littoral areas in estuaries do indeed provide small juvenile fishes with refuge from small and large piscivorous fishes is provided by published papers from 4 different estuary types in South Africa, covering both subtropical and warm-temperate systems. Based on the overall published information, the argument for shallow (<1 m depth) estuarine waters providing major protection for newly settled juveniles appears to be weak in northern Australia but strong in South Africa. The global situation, as outlined in this response, is more supportive of low piscivorous predation in shallow nursery habitats, but further targeted research is needed before we can confirm that littoral estuarine waters are indeed a universal keystone attribute in this regard.
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Rosa, Leonardo Cruz, and Carlos Emilio Bemvenuti. "Effects of the burrowing crab Chasmagnathus granulata (Dana) on meiofauna of estuarine intertidal habitats of Patos Lagoon, Southern Brazil." Brazilian Archives of Biology and Technology 48, no. 2 (March 2005): 267–74. http://dx.doi.org/10.1590/s1516-89132005000200014.
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This study aimed to evaluate the effects of the burrowing crab Chasmagnathus granulata on meiofauna at three intertidal habitats across a tidal exposure gradient (i.e., an emerged salt marsh, an emerged mudflat and a submerged mudflat) in an estuarine embayment of Patos Lagoon, Southern Brazil. Meiofauna community was dominated by nematodes and ostracods, following by copepods and turbellarians. Densities of all studied organisms varied significantly among habitats. Highest values were observed in submerged mudflat while lower in salt marsh. Nematodes were unaffected by crab in either habitat, whereas ostracod, copepod and turbellarian densities were significantly lower in disturbed than control areas in both mudflat habitats. Any meiofaunal group was affected in salt marsh, probably due to a less intense disturbance. The results showed that the burrowing crab C. granulata could play an important role on meiofauna community structure in estuarine intertidal habitats of Patos Lagoon, because crab disturbance seemed to affect mainly surface populations, especially in mudflat. However, the meiofauna response to crab disturbance was variable among habitats depending of the intensity and the frequency of the disturbance.
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Romero-Berny, Emilio I., Ernesto Velázquez-Velázquez, Juan J. Schmitter-Soto, and Isaías H. Salgado-Ugarte. "The influence of habitat on the spatio-temporal dynamics of fish assemblages in a lagoon-estuarine system of the Mexican Pacific." Latin American Journal of Aquatic Research 48, no. 1 (March 3, 2020): 23–37. http://dx.doi.org/10.3856/vol48-issue1-fulltext-2349.
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Fish assemblages change significantly with physical and chemical characteristics of water; however, their response to the variability of geomorphic habitats has been rarely evaluated in lagoon-estuarine in one of these systems of the Mexican Pacific. Spatio-temporal variation of fish assemblage structure was assessed for three habitats: lagoon, estuarine, channel and inlet. The hypothesis was that sheltered areas support comparatively higher richness and abundance of fish species, with more small-sized specimens than the most exposed areas. We found that the ichthyofauna differed significantly among habitats. Several species were smaller in the lagoon compared with the other habitats, suggesting a use of the lagoon as a nursery ground. Moreover, dominant species for the lagoon were rarely found or absent in the inlet, whereas others were found only present or with higher abundance in the inlet. Although seasonal differences in richness and composition were detected, the evidence of fish-habitat associations for many species was noticeable regardless of seasonality, probably due to a high percentage of resident species during the annual cycle. The lagoon supports a greater abundance and species richness, due to a more sheltered and structured habitat, evidencing habitat-driven segregation in fish assemblages, and an aspect that should be incorporated for management of coastal ecosystems.
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Dunbar, Kimberley, Ronald Baker, and Marcus Sheaves. "Effects of forest width on fish use of fringing mangroves in a highly urbanised tropical estuary." Marine and Freshwater Research 68, no. 9 (2017): 1764. http://dx.doi.org/10.1071/mf16098.
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The size and shape of a habitat patch can influence patterns of species utilisation. The present study examined how the width of fringing mangrove habitats affects the composition and use patterns of the fish assemblage using mangrove edge habitats on the flooding tide. Underwater cameras surveyed fish approaching mangrove habitats, ranging from a thin fringe 5m wide to forests over 75m wide, in a highly modified tropical estuary. The fish assemblage composition was similar across all mangrove widths, although the temporal patterns of use varied among mangrove widths for some species. The mean maximum number of individuals in the field of view was similar among mangrove widths, but fish were visible for a significantly greater proportion of time in videos from narrow (<20m) than wide (≥20m) mangrove stands (15v. 3% respectively). At least some fish were visible in the field of view in narrow mangrove fringes throughout the first hour of the flood tide, whereas in wide mangroves areas the presence of fish declined over time. The findings suggest that estuarine fish are using mangrove edge habitat regardless of width, making narrow mangroves viable habitats for estuarine fish.
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Francis, Malcolm P., Mark A. Morrison, John Leathwick, and Cameron Walsh. "Predicting patterns of richness, occurrence and abundance of small fish in New Zealand estuaries." Marine and Freshwater Research 62, no. 11 (2011): 1327. http://dx.doi.org/10.1071/mf11067.
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Estuarine fish habitats are vulnerable to human impacts and are poorly studied. We surveyed 69 of New Zealand’s 443 estuaries across 1500 km to: determine species composition of small fishes; model and predict their richness, occurrence and abundance; test marine classification schemes as a basis for Marine Protected Areas; and inform impact mitigation measures. Boosted regression tree models produced acceptable fits for richness and occurrence at estuary and site scales and abundance at the site scale. Richness was greatest in northern North Island; the best predictors were estuary area and area of intertidal habitat. Within estuaries, richness increased towards the head, as water clarity declined and the substratum became muddier. Air temperature, estuary and intertidal area, tidal range and freshwater and seawater influx were the best predictors of occurrence at the estuary scale; water temperature and salinity were important at the site scale. Biological classification schemes seldom improved model fits and have little predictive utility. Richness predictions were made for 380 estuaries and occurrence predictions for 16 species. These predictions inform resource managers about estuarine fishes within their jurisdiction, bypassing the need to undertake expensive field surveys. However, sampling of environmental predictors is still required to drive some models.
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Mariano, Dante Luís Silva, and Francisco Barros. "Intertidal benthic macrofaunal assemblages: changes in structure along entire tropical estuarine salinity gradients." Journal of the Marine Biological Association of the United Kingdom 95, no. 1 (November 15, 2014): 5–15. http://dx.doi.org/10.1017/s002531541400126x.
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Spatial variation in the structure of macrobenthic assemblages on intertidal flats is known to be related to different environmental variables. Most of the studies have observed that along the estuarine gradient, salinity is the most important variable driving the patterns of the macrobenthic assemblages. However, the great majority of studies have been done on single estuarine systems in temperate regions. We investigated the relationship between the macrobenthic assemblages in intertidal habitats and the environmental variables along three tropical estuaries. From lower to upper estuarine regions we sampled benthic macrofauna, salinity and sediments. The structure of the benthic assemblages was primarily related to salinity. There was a decrease in the number of taxa from the upper to the lower estuarine regions, indicating important deviation from Remane's model of estuarine diversity. There were important similarities of taxa abundance along different estuarine salinity gradients which can be properly tested in other tropical and temperate regions. We advocate that in order to adopt general and robust management practices it is essential to identify broad patterns and general rules governing estuarine systems.
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Condini, Mario V., Paula E. R. Pereyra, Alexandre M. Garcia, Tatiana D. Saint'pierre, Gianfranco Ceni, Rafael Lugo, Nelson F. Fontoura, João P. Vieira, and Cristiano Q. Albuquerque. "Use of fresh water by an estuarine-resident marine catfish: evidence from gonadal and otolith chemistry analyses." Journal of the Marine Biological Association of the United Kingdom 99, no. 7 (June 20, 2019): 1667–74. http://dx.doi.org/10.1017/s0025315419000493.
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AbstractIn this study, we examine how the Guri catfish Genidens genidens uses estuarine and freshwater habitats along the largest South American coastal lagoon, through the chemical analysis of otoliths and microscopic analysis of gonads. Chemical composition (Sr:Ca) of otolith edges allowed distinguishing between individuals who used the estuarine or freshwater compartments of the lagoon. The analysis of core-to-edge chemical profiles of each individual otolith revealed that the population may present two different patterns of habitat use along the lagoon. The ‘type 1’ pattern (89.5%) includes fish who appear to have been born in estuarine waters, whereas ‘type 2’ (9.5%) includes those fish born in fresh water. Nevertheless, juveniles from both patterns appear to migrate to estuarine waters. The gonad analysis shows G. genidens may reproduce in fresh water, as nearly 57% of all sampled fish were found to spawn in the freshwater portion of the lagoon. Also, the otolith core of many adult fish presented freshwater signatures, thus suggesting consistent fresh water use during early life. Our findings based on otolith and gonadal analyses challenge the previous classification of G. genidens as an estuarine resident. Rather, our results allow the suggestion that this species should be placed in the ‘estuarine and fresh water’ guild, which includes both fish completing their life cycles within the estuary and fish who consistently use freshwater habitats.
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Matich, Philip, Robert J. Nowicki, Jonathan Davis, John A. Mohan, Jeffrey D. Plumlee, Bradley A. Strickland, Thomas C. TinHan, R. J. David Wells, and Mark Fisher. "Does proximity to freshwater refuge affect the size structure of an estuarine predator (Carcharhinus leucas) in the north-western Gulf of Mexico?" Marine and Freshwater Research 71, no. 11 (2020): 1501. http://dx.doi.org/10.1071/mf19346.
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The life histories of estuarine species are often adapted to the environmental variability they experience. However, estuaries are increasingly vulnerable to natural and anthropogenic changes, necessitating an understanding of how shifting conditions affect the survival, behaviour and population structure of estuarine-dependent animals. In this study we used data from fisheries-independent surveys collected across six estuaries with variable salinity regimes in Texas, USA, from 1975 to 2016 to investigate the role sources of freshwater inflow play in shaping juvenile bull shark Carcharhinus leucas size structure. High frequencies of co-occurrence with similarly sized conspecifics (59% of capture events) suggest bull sharks segregated within Texan estuaries based on body size. Bull shark sizes increased with distance to the nearest source of freshwater inflow, although effect sizes were small and access to freshwater habitats may be more important in shaping size-dependent distribution patterns. River mouths were disproportionately used by smaller juveniles (<90-cm total length, TL) and avoided by larger juveniles (>135cm TL). However, the use of river mouths decreased in estuaries characterised by limited freshwater inflow and greater variability in salinities at river mouths, highlighting geographic differences in the functions these habitats provide as potential environmental and predator refugia. Young-of-the-year (i.e. age-0) sharks also increased their use of river mouths throughout the 40-year study period, revealing the growing importance of river mouths as potential nursery habitats.
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PRASCHAG, PETER, ROHAN HOLLOWAY, ARTHUR GEORGES, MARTIN PÄCKERT, ANNA K. HUNDSDÖRFER, and UWE FRITZ. "A new subspecies of Batagur affinis (Cantor, 1847), one of the worlds most critically endangered chelonians (Testudines: Geoemydidae)." Zootaxa 2233, no. 1 (September 16, 2009): 57–68. http://dx.doi.org/10.11646/zootaxa.2233.1.3.
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Estuarine Batagur are among the most critically endangered chelonian species. We assess the taxonomic status of the recently discovered Cambodian relic population of Batagur by phylogenetic analyses of three mitochondrial (2096 bp) and three nuclear DNA fragments (1909 bp) using sequences from all other Batagur species and selected allied geoemydids. Furthermore, we calculated haplotype networks of the mitochondrial cytochrome b gene for Cambodian terrapins, B. affinis, B. baska, and B. kachuga and compare external morphology of estuarine Batagur populations. Genetically, Cambodian Batagur are closely related with, but distinct from B. affinis from Sumatra and the west coast of the Malay Peninsula. Morphologically, Cambodian Batagur resemble the distinctive B. affinis populations from the eastern Malay Peninsula that were not available for genetic study. We suggest that the Batagur populations from the eastern Malay Peninsula and Cambodia represent a new subspecies of B. affinis that once was distributed in estuaries surrounding the Gulf of Thailand (Batagur affinis edwardmolli subsp. nov.). Its patchy extant distribution is most probably the result of large-scale habitat alteration and century-long overexploitation. In addition, our phylogenetic analyses suggest repeated switches between riverine and estuarine habitats during the evolution of the extant Batagur species.
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Forster, Rodney M., and Bruno Jesus. "Field spectroscopy of estuarine intertidal habitats." International Journal of Remote Sensing 27, no. 17 (September 2006): 3657–69. http://dx.doi.org/10.1080/01431160500500367.
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Bigford, Thomas E., and TyAnn Lee. "Introduction: Conserving Coastal and Estuarine Habitats." Coastal Management 44, no. 3 (May 3, 2016): 157–60. http://dx.doi.org/10.1080/08920753.2016.1160200.
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Farr, Emily R., Michael R. Johnson, Mark W. Nelson, Jonathan A. Hare, Wendy E. Morrison, Matthew D. Lettrich, Bruce Vogt, et al. "An assessment of marine, estuarine, and riverine habitat vulnerability to climate change in the Northeast U.S." PLOS ONE 16, no. 12 (December 9, 2021): e0260654. http://dx.doi.org/10.1371/journal.pone.0260654.
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Climate change is impacting the function and distribution of habitats used by marine, coastal, and diadromous species. These impacts often exacerbate the anthropogenic stressors that habitats face, particularly in the coastal environment. We conducted a climate vulnerability assessment of 52 marine, estuarine, and riverine habitats in the Northeast U.S. to develop an ecosystem-scale understanding of the impact of climate change on these habitats. The trait-based assessment considers the overall vulnerability of a habitat to climate change to be a function of two main components, sensitivity and exposure, and relies on a process of expert elicitation. The climate vulnerability ranks ranged from low to very high, with living habitats identified as the most vulnerable. Over half of the habitats examined in this study are expected to be impacted negatively by climate change, while four habitats are expected to have positive effects. Coastal habitats were also identified as highly vulnerable, in part due to the influence of non-climate anthropogenic stressors. The results of this assessment provide regional managers and scientists with a tool to inform habitat conservation, restoration, and research priorities, fisheries and protected species management, and coastal and ocean planning.
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Pereira, Pedro Henrique Cipresso, Marcus Vinicius Bezerra dos Santos, Daniel Lino Lippi, Pedro Henrique de Paula Silva, and Breno Barros. "Difference in the trophic structure of fish communities between artificial and natural habitats in a tropical estuary." Marine and Freshwater Research 68, no. 3 (2017): 473. http://dx.doi.org/10.1071/mf15326.
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The present study tested the hypothesis that artificial habitats (pier and bridge) harbour different fish trophic guilds compared with natural habitats (mangrove roots) and that the trophic structure of fish communities on estuarine artificial habitats resembles adjacent coral reefs. High-definition cameras were used to survey the fish community associated with the different structures over a 6-month period. Benthos was also analysed following the point intercept method on the different habitats. In the estuary, fish abundance was up to threefold higher and species richness twofold higher on artificial structures compared with the natural habitat. Mangrove roots were mainly inhabited by juvenile carnivores, whereas the pier and bridge were mostly inhabited by sessile invertebrate feeders and roving herbivores. A less diverse benthic community was found on mangrove roots, mostly composed of mud and algae. In contrast, benthos at the bridge and pier was more diverse and dominated by sponges, octocorals and oysters. In addition, fish trophic structure from an adjacent coral reef area showed more than 60% similarity with the fish community on the artificial structures surveyed. The results of the present study indicate that artificial hard structures support unique fish communities compared with natural estuarine mangrove habitats.
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Toledo, Pamela, Edwin J. Niklitschek, Audrey M. Darnaude, Félix P. Leiva, Chris Harrod, Sergio Lillo, Vilma Ojeda, et al. "The trophic ecology of partial migration: insights from Merluccius australis off NW Patagonia." ICES Journal of Marine Science 77, no. 5 (June 18, 2020): 1927–40. http://dx.doi.org/10.1093/icesjms/fsaa065.
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Abstract Partial migration, where migrant and resident organisms coexist within the same population, has been found in many fishes. Although it seems obvious that different life cycles exploit habitats and food webs differently, few assessments about the trophic consequences of partial migration are available. To unveil part of this complexity, we combined otolith chemistry with stable isotope analyses data for hind-casting Merluccius australis habitat use and diet composition at age. By providing detailed information about lifetime variability in diet, trophic position, and prey demand of four M. australis life-cycle types, we show that these groups feed differentially in estuarine and oceanic habitats throughout their ontogeny. Although trophic positions were similar between habitats for juvenile and subadults, substantial differences between life-cycle types were found regarding lifetime diet and trophic demand. Thus, the more abundant and heavily exploited oceanic stock of M. australis was heavily dependent of estuarine habitats within the Patagonian Fjords System, where it consumes large biomasses of Macruronus magellanicus, Pasiphaea, Sprattus fuegensis, and Euphausiidae at earlier stages. We show ignoring trophic consequences of partial migration and life-cycle diversity may produce highly biased results, both in terms of prey and habitat use, which appears critical for multispecies and ecosystem management approaches.
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Becker, Alistair, and Matthew D. Taylor. "Nocturnal sampling reveals usage patterns of intertidal marsh and subtidal creeks by penaeid shrimp and other nekton in south-eastern Australia." Marine and Freshwater Research 68, no. 4 (2017): 780. http://dx.doi.org/10.1071/mf15325.
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The life cycle of most penaeid prawns includes a juvenile phase in protected coastal environments such as estuaries and embayments. In the tropics, some penaeids are known to utilise intertidal habitats, yet in temperate regions of Australia the use of marshes has not been investigated. We focused on determining the extent to which Melicertus plebejus and Metapenaeus macleayi directly utilise intertidal marsh habitat using fyke nets. Using cast nets, we also assessed the abundance of the two focal species in middle and edge habitat of adjacent subtidal creeks. Despite collecting 8300 crustaceans and 4259 teleosts, only 8M. plebejus were sampled on the marsh. Abundances of M. macleayi were greater with 90 individuals collected. Within the subtidal creeks larger M. macleayi were collected in the middle habitat and the abundance of both penaeids varied among different creeks. The nekton community as a whole also differed among creeks within marshes. This study has demonstrated that juvenile M. plebejus and M. macleayi do not directly utilise intertidal marsh habitats. Despite this, marshes may provide important resources for prawns through the export of carbon. Future isotope studies would provide valuable information in this regard, providing a broader understanding of penaeids and specific estuarine habitats.
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Levings, C. D., N. A. Hvidsten, and B. Ø. Johnsen. "Feeding of Atlantic salmon (Salmo salar L.) postsmolts in a fjord in central Norway." Canadian Journal of Zoology 72, no. 5 (May 1, 1994): 834–39. http://dx.doi.org/10.1139/z94-113.
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The feeding habits of postsmolt Atlantic salmon (Salmo salar) caught by two-boat trawling were studied in Trondheimsfjord in central Norway. Fish caught in the inner fjord near the estuaries of the Orkla and Gaula rivers had recently fed on food produced in freshwater and estuarine habitats, namely stonefly and mayfly nymphs and gammarid amphipods. Stomach contents of postsmolts caught farther seaward were dominated by adult insects, with smaller proportions of the food volume originating from marine pelagic (larval fish, hyperiid amphipods, calanoid copepods) and nearshore (gammarid amphipods) habitats.
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Passos, Ana Carolina dos, Riguel Feltrin Contente, Ciro Colodetti Vilar de Araujo, Felippe Alexandre Lisboa de Miranda Daros, Henry Louis Spach, Vinícius Abilhôa, and Luis Fernando Fávaro. "Fishes of Paranaguá Estuarine Complex, South West Atlantic." Biota Neotropica 12, no. 3 (September 2012): 226–38. http://dx.doi.org/10.1590/s1676-06032012000300022.
Full textAbstract:
The objective of this work was to present an updated checklist of the currently known fishes in the Paranaguá Estuarine Complex (PEC) and provides comments on conservation status for the treated species. We used a large dataset derived from a pool of studies which have been conducted within there along the last 30 years. Each study was based on monthly samplings and conducted in several estuarine habitat; thus, the pool covers practically all estuarine habitats and takes into account the seasonal cycle in the system. The PEC ichthyofauna represents a mixture between that fauna typical from the tropical Brazilian coast and that with affinities of temperate Argentinean and Uruguayan zones. The PEC harbors a rich fish fauna of 213 species, inserted in the families that are common along the Brazilian coast. Only a minor part (8%) of the PEC fish fauna was evaluated as regards the conservation status, mostly because of the lack of basic biological and ecological information for most species. Despite part of the among-estuaries differences are due to different and incomplete sampling efforts, the richness in the PEC is surprisingly higher than other systems in Brazil and around world, which emphasize the importance of the region for global biodiversity conservation.
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Park, Joo Myun, Ralf Riedel, Hyun Hee Ju, and Hee Chan Choi. "Fish Assemblage Structure Comparison between Freshwater and Estuarine Habitats in the Lower Nakdong River, South Korea." Journal of Marine Science and Engineering 8, no. 7 (July 5, 2020): 496. http://dx.doi.org/10.3390/jmse8070496.
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Variabilities of biological communities in lower reaches of urban river systems are highly influenced by artificial constructions, alterations of flow regimes and episodic weather events. Impacts of estuary weirs on fish assemblages are particularly distinct because the weirs are disturbed in linking between freshwater and estuarine fish communities, and migration successes for regional fish fauna. This study conducted fish sampling at the lower reaches of the Nakdong River to assess spatio-temporal variations in fish assemblages, and effects of estuary weir on structuring fish assemblage between freshwater and estuary habitats. In total, 20,386 specimens comprising 78 species and 41 families were collected. The numerical dominant fish species were Tachysurus nitidus (48.8% in total abundance), Hemibarbus labeo (10.7%) and Chanodichthys erythropterus (3.6%) in the freshwater region, and Engraulis japonicus (10.0%), Nuchequula nuchalis (7.7%) and Clupea pallasii (5.2%) in the estuarine site. The fish sampled were primarily small species or the juveniles of larger species at the estuary region, while all life stages of fishes were observed at the freshwater habitats. The diversity patterns of fish assemblages varied greatly according to study site and season, with higher trends at estuarine sites during the warm-rainy season. No significant difference in diversity between freshwater and estuarine sites during the cold-dry season were found. Multivariate analyses of fish assemblage showed spatial and seasonal differences of assemblage structures. Higher effects of between-site variability but not within seasonal variability at each site were observed. Variations in assemblage structures were due to different contributions of dominant species in each habitat. Common freshwater species characterized the fish assemblage in the freshwater region, while marine juveniles were significantly associated with the estuarine habitat. The results from the ecological guild analyses showed distinct ecological roles for freshwater and marine species, and overlapping roles for fish sampled at the fishways. The lower reaches of the Nakdong River are an important ecosystem for both freshwater and marine juveniles. Nakdong River estuarine residents and migrant fishes, however, have been negatively affected by the construction of the weir (gravity dam), due to the obstruction to migration from and to freshwater habitats. Conservation and management policies aimed at minimizing anthropogenic influences on estuary ecosystems should focus on evaluating ecological functions of estuary weirs.
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Hackradt, Carlos Werner, Fabiana Cézar Félix-Hackradt, Helen Audrey Pichler, Henry Louis Spach, and Lilyane de Oliveira e Santos. "Factors influencing spatial patterns of the ichthyofauna of low energy estuarine beaches in southern Brazil." Journal of the Marine Biological Association of the United Kingdom 91, no. 6 (November 2, 2010): 1345–57. http://dx.doi.org/10.1017/s0025315410001682.
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Estuarine beaches are low energy environments found along the coast in several protected places around the world, such as estuaries, bays or areas protected by submerged bars or coral reefs. Although common, these places have been poorly studied. Using a seine net, six beaches were sampled along an environmental gradient for 12 months. During this period, an increase of the dominant species following the increase in salinity and energy values was observed, whilst the opposite pattern occurred for species richness and abundance. Univariate and multivariate analyses showed spatial and temporal variations between beaches and months. Depth and marginal habitats appear to be more important factors than wave height and period, temperature, salinity and pH, which are normally used to describe fish habitat utilization patterns in beaches and estuaries. Nevertheless, specific sampling designs should be proposed to evaluate properly these questions.
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Dixon, Olivia, Johanna Gammal, Dana Clark, Joanne I. Ellis, and Conrad A. Pilditch. "Estimating Effects of Sea Level Rise on Benthic Biodiversity and Ecosystem Functioning in a Large Meso-Tidal Coastal Lagoon." Biology 12, no. 1 (January 10, 2023): 105. http://dx.doi.org/10.3390/biology12010105.
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Estuaries are among the world’s most productive ecosystems, but due to their geographic location, they are at the forefront of anthropogenic pressures. Sea level rise (SLR) is one major consequence of climate change that poses a threat to estuaries with extensive intertidal habitats. The ecological implications of intertidal habitat loss have been largely overlooked despite their likely significance. We aimed to address this knowledge gap by investigating how benthic macroinvertebrate communities and their contributions to ecosystem function are likely to respond to SLR. Based on a spatially extensive dataset (119 sites) from a large coastal lagoon, depth, sediment chlorophyll concentrations, mud content, and average current speed were identified as the main drivers of community compositional turnover. Shifts in benthic community structure and associated functional implications were then evaluated using depth as a proxy for SLR. Three main macrofaunal groups representing intertidal, shallow subtidal, and deep subtidal habitats were identified. Functional trait analysis indicated low functional redundancy for a key intertidal suspension-feeding bivalve (Austrovenus stutchburyi) and the lack of a shallow subtidal functional replacement should intertidal habitats become inundated. These findings strongly suggest SLR and the associated environmental changes will alter estuarine macroinvertebrate communities, with implications for future ecosystem function and resilience.
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Taddese, Fasil, Marc Schallenberg, Pavel Mikheev, Matt G. Jarvis, and Gerard P. Closs. "Ichthyofaunal assemblages in shallow littoral habitats of permanently open estuaries and intermittently closed and open lakes or lagoons in Otago, New Zealand." Marine and Freshwater Research 69, no. 8 (2018): 1222. http://dx.doi.org/10.1071/mf17334.
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Fish assemblages of New Zealand estuaries are poorly studied, and knowledge of the effects of estuary–ocean connections on the ichthyofaunal composition of estuaries remains limited. Understanding the status of fish composition of estuaries is crucial for planning for sustainable management of aquatic ecosystems. In the present study we sampled fish using a seine net from lower reaches of six permanently open estuaries and six intermittently closed and open lakes or lagoons (ICOLLs) along the Otago coastline during winter 2016 and summer 2017. Marked differences in ichthyofaunal composition were observed in the shallow littoral habitats of permanently open estuaries and ICOLLs. Fish assemblages reflected estuary–ocean connection status of estuaries during both seasons. ICOLLs showed greater fish abundance than permanently open systems. Fish abundance was higher in summer than in winter in both estuary types. Fish species with marine–estuarine opportunist and estuarine–migrant life histories dominated permanently open estuaries. Conversely, species with a diadromous life history but known to form landlocked populations were abundant in ICOLLs. Salinity and temperature were correlated with fish abundance in both estuary types.
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Withers, Kim. "Shorebird Use of Coastal Wetland and Barrier Island Habitat in the Gulf of Mexico." Scientific World JOURNAL 2 (2002): 514–36. http://dx.doi.org/10.1100/tsw.2002.112.
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The Gulf Coast contains some of the most important shorebird habitats in North America. This area encompasses a diverse mixture of estuarine and barrier island habitats with varying amounts of freshwater swamps and marshes, bottomland hardwood forests, and coastal prairie that has been largely altered for rice and crawfish production, temporary ponds, and river floodplain habitat. For the purposes of this review, discussion is confined to general patterns of shorebird abundance, distribution, and macro- and microhabitat use in natural coastal, estuarine, and barrier island habitats on the Gulf of Mexico Coast. The following geographic regions are considered: Northwestern Gulf (Rio Grande to Louisiana-Mississippi border), Northeastern Gulf (Mississippi to Florida Keys), and Mexico (Rio Grande to Cabo Catoche [Yucatan Strait]).Wintering and migrating shorebirds are most abundant along the Gulf Coast in Texas and Tamaulipas, particularly the Laguna Madre ecosystem. Other important areas are the Southwest Coast region of Florida and the area between Laguna Terminos and Puerto Progresso in Mexico. In general, relative abundances of shorebirds increase from north to south, and decrease south of the Tropic of Cancer (23° 27’ N). Based on bimonthly maximum counts within 5° latitudinal bands, the region between 25–30° N is used most heavily by wintering and spring migrating birds.Non-vegetated coastal wetland habitats associated with bays, inlets and lagoons, particularly tidal flats, and sandy beaches are the habitats that appear to be favored by wintering and migrating shorebirds. In general, these habitats tend to occur as habitat complexes that allow for movement between them in relation to tidal flooding of bay-shore habitats. This relationship is particularly important to Piping Plover and may be important to others.Although vegetated habitats are used by some species, they do not appear to attract large numbers of birds. This habitat is most widespread between the Texas-Louisiana border and the Florida Panhandle region, but it has not been studied extensively. Shorebird abundance and habitat use in this area need to be addressed.