Unvegetated Habitats Research Articles

Blue crab (Callinectes sapidus) population structure in southern New England tidal rivers: Patterns of shallow-water, unvegetated habitat use and quality.

The blue crab, Callinectes sapidus, has a broad geographic distribution encompassing coastal waters of the eastern United States and Gulf of Mexico, but intraspecific patterns of habitat use and quality are lacking at northern latitudes. This study examined the population structure of blue crabs in the Seekonk and Taunton Rivers (Rhode Island and Massachusetts, USA): two tidally influenced rivers contiguous with the Narragansett Bay Estuary and dominated by shallow-water, unvegetated habitats. Crabs were collected fortnightly from May through August (2012-2016), and abundance- and growth-based metrics were used to assess riverine habitat use and quality. These metrics were also analyzed with respect to crab life history traits and in situ abiotic conditions to elucidate patterns of habitat selection throughout ontogeny. Crabs measuring 8 to 185 mm carapace width (CW; n = 2,577) were collected, and two distinct age-classes occupied the rivers during the spring and summer (maximum abundance ~ 5 crabs/10 m2). The younger age-0+ cohort was numerically dominant (~ 88% of total catch) and comprised of male and juvenile female crabs (mean ± SD abundance = 0.28 ± 0.26 males/10 m2 and 0.14 ± 0.12 juvenile females/10 m2). Males accounted for the majority of age-1+ crabs (~ 83% of cohort), yet sexually mature females were also observed (9% of cohort; mean ± SD abundance = 0.04 ± 0.06 adult females/100 m2; size at 50% maturity ± 95 CI = 129.0 ± 0.2 mm CW). Crabs were spatially segregated along a salinity gradient with males and juvenile females prevalent in oligohaline waters (upper river salinity ~ 5 ppt) and adult females mainly concentrating in higher salinity areas (mid- and lower river salinity ~ 11-21 ppt). Seasonal and interannual patterns in crab abundance also differed by sex and ontogeny. Peak catches of males and juvenile females occurred during the spring and mid-summer, and annual abundances were positively related to dissolved oxygen (DO) concentrations. In contrast, mature females were most abundant during August and years with elevated water temperatures. The absolute and relative growth rates of juvenile crabs equaled 0.9 ± 0.3 mm CW/day and 1.5 ± 0.6 % CW/day, respectively, and were directly related to DO levels. A synoptic examination of crab abundance and growth across a broad geographic range indicated that shallow-water, unvegetated habitats presently serve as functional nurseries in southern New England tidal rivers.

Storm tide amplification and habitat changes due to urbanization of a lagoonal estuary

Abstract. In recent centuries, human activities have greatly modified the geomorphology of coastal regions. However, studies of historical and possible future changes in coastal flood extremes typically ignore the influence of geomorphic change. Here, we quantify the influence of 20th-century man-made changes to Jamaica Bay, New York City, on present-day storm tides. We develop and validate a hydrodynamic model for the 1870s based on detailed maps of bathymetry, seabed characteristics, topography, and tide observations for use alongside a present-day model. Predominantly through dredging, landfill, and inlet stabilization, the average water depth of the bay increased from 1.7 to 4.5 m, tidal surface area decreased from 92 to 72 km2, and the inlet minimum cross-sectional area expanded from 4800 to 8900 m2. Total (freshwater plus salt) marsh habitat area has declined from 61 to 15 km2 and intertidal unvegetated habitat area from 17 to 4.6 km2. A probabilistic flood hazard assessment with simulations of 144 storm events reveals that the landscape changes caused an increase of 0.28 m (12 %) in the 100-year storm tide, even larger than the influence of global sea level rise of about 0.23 m since the 1870s. Specific anthropogenic changes to estuary depth and area as well as inlet depth and width are shown through targeted modeling and dynamics-based considerations to be the most important drivers of increasing storm tides.

The role of seagrass vegetation and local environmental conditions in shaping benthic bacterial and macroinvertebrate communities in a tropical coastal lagoon

We investigated the influence of seagrass canopies on the benthic biodiversity of bacteria and macroinvertebrates in a Red Sea tropical lagoon. Changes in abundance, number of taxa and assemblage structure were analyzed in response to seagrass densities (low, SLD; high, SHD; seagrasses with algae, SA), and compared with unvegetated sediments. Biological and environmental variables were examined in these four habitats (hereafter called treatments), both in the underlaying sediments and overlaying waters, at three randomly picked locations in March 2017. Differences between treatments were more apparent in the benthic habitat than in the overlaying waters. The presence of vegetation (more than its cover) and changes in sedimentary features (grain size and metals) at local scales influenced the observed biological patterns, particularly for macroinvertebrates. Of note, the highest percentage of exclusive macroinvertebrate taxa (18% of the gamma diversity) was observed in the SHD treatment peaking in the SA for bacteria. Benthic macroinvertebrates and bacteria shared a generally low number of taxa across treatments and locations; approximately, 25% of the gamma diversity was shared among all treatments and locations for macrofauna, dropping to 11% for bacteria. Given the low overlap in the species distribution across the lagoon, sustaining the connectivity among heterogeneous soft sediment habitats appears to be essential for maintaining regional biodiversity. This study addresses a current scientific gap related to the relative contributions of vegetated and unvegetated habitats to biodiversity in tropical regions.

Blue Carbon Stocks and Cross-Habitat Subsidies

Blue carbon ecosystems (including saltmarsh, mangrove, seagrass meadows, and other soft sediment habitats) play a valuable role in aquatic carbon dynamics and contribute significantly to global climate change mitigation. However, these habitats are undergoing rapid and accelerating shifts in extent due to climate change and anthropogenic impactsstressors. Here, we demonstrate that blue carbon stocks vary across habitats and that cross-habitat subsidies of carbon contribute significantly to blue carbon stocks. Using a case study estuary from New Zealand, organic carbon stocks in above ground biomass and sediment to 100 cm varied significantly between habitat types, from saltmarsh (90 t ha-1), to mangrove (46 t ha-1), to seagrass (27 t ha-1) and unvegetated habitats (26 t ha-1). Despite being typically overlooked in blue carbon literature, unvegetated habitats contained the majority of estuarine carbon stocks when adjusted for their large extent within the estuary (occupying 68.4% of the estuarine area and containing 57% of carbon stocks). When carbon stocks were further refined based on δ13C and δ15N mixing model results, coastal vegetation (saltmarsh, mangrove, seagrass) was found to provide important cross-habitat subsidies exchanges of carbon throughout the estuary, including contributing an estimated 41% of organic carbon within unvegetated sediments, and 51% of the total carbon stock throughout the estuary (yet occupying only 31.6% of the estuary). Given the connected nature of blue carbon ecosystems these findings illustrate the importance of considering the contribution and cross habitat subsidies of both vegetated and unvegetated habitats to blue carbon stocks in estuaries. This provides critical context when assessing the impact of shifts in habitat distributions due to impacts from climate change and anthropogenic stressors.

Spatiotemporal Dynamics of Mediterranean Shallow Coastal Fish Communities along a Gradient of Marine Protection

The importance of habitat factors in designing marine reserves and evaluating their performance over time has been regularly documented. Over three biennial sampling periods, we examined the effects of vegetated coverage and habitat diversity (i.e., patchiness) on fish density, community composition, and species-specific patterns along a gradient of protection from harvest in the shallow Spanish southern Mediterranean, including portions of the Tabarca marine reserve. With the exception of two herbivores (Sarpa salpa and Symphodus tinca), vegetated cover did not significantly affect fish densities, while habitat diversity was an influential factor across all three sampling periods. Overall, fish density was more positively associated with more continuous vegetated or unvegetated habitats, and was greatest in areas of highest protection (Tabarca II – Isla Nao site). These patterns were usually observed for four abundant fish species (Boops boops, Chromis chromis, Oblada melanura, and S. salpa). Fish community composition was distinct in the most protected portion of the Tabarca reserve, where it was also most stable. Our findings align with previous investigations of the Tabarca reserve and its surrounding areas, and demonstrate its continued effectiveness in conserving fish biomass and habitat. Together with effective management, marine reserves can facilitate greater species abundance, more stable biological communities, and resilient ecosystems.

Mangrove or mudflat: Prioritising fish habitat for conservation in a turbid tropical estuary

Mangrove habitats are typically the focus of conservation efforts in tropical estuaries because their structural complexity is thought to support greater biodiversity and nursery function than unvegetated habitats. However, evidence for this paradigm has been equivocal in turbid tropical estuaries where unvegetated mudflats are also highly productive. The present study compared the community composition, biodiversity, nursery-role and commercial fish biomass in two mangrove habitats and one mudflat habitat in the Gulf of Paria, Trinidad. A total of 12 705 fishes, comprising 63 species from 26 families, were sampled in mangrove creeks, seaward mangrove fringe and the subtidal margin of an intertidal mudflat from June 2014 to June 2015. The composition of the creek and mudflat communities were distinct, while the community of the mangrove fringe more closely resembled the mudflat than the mangrove creeks. Mean species richness (MSR), total species richness (TSR) extrapolated from species accumulation curves, and juvenile species richness (JSR) were significantly greater in the mudflat (MSR = 11.4 ± 1.0; TSR = 75 ± 14; JSR = 9.1 ± 0.8) than mangrove creeks (MSR = 9.0 ± 0.5; TSR = 49 ± 3; JSR = 6.1 ± 0.4) and the seaward mangrove fringe (MSR = 6.4 ± 0.7; TSR = 58 ± 14; JSR = 5.2 ± 0.4). Meanwhile, Shannon Weiner diversity, juvenile fish abundance and commercial fish biomass were comparable between habitats. These findings caution against the generalisation that mangroves are the most important habitat for fishes in turbid tropical estuaries. There is now a growing body of evidence that mudflats warrant consideration as important repositories of biodiversity and nursery function for juvenile fishes.

Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

Decapod assemblages in Zostera marina beds from two bays adjacent to unvegetated habitats were investigated to assess their influence on decapod assemblages. Thirty-eight decapod species belonging to four taxa were collected using a small beam trawl at four habitat types from two different locations off the coast of Namhae Island, South Korea. Dominant decapod taxon at all habitats was the caridean shrimps, with Eualus leptognathus, Heptacarpus pandaloides, Latreutes anoplonyx, La. Laminirostris, and Palaemon macrodactylus being the most abundant caridean species. Crabs were characterized with the highest biomass, but with moderate species richness and abundance. Penaeoid and sergestoid shrimps only accounted for <1% of the total decapod abundance. The number of species and their abundance of decapod assemblages varied greatly by habitat type, season, and diel patterns, but not diversity. Species number and abundance peaked in seagrass beds of southern exposed bays during the autumn and were lowest in unvegetated habitats during the summer months. Diel decapod catch rates were higher at night. Dense seagrass vegetation and nighttime supported higher decapod mean densities, but not species richness and diversity. Multivariate analyses revealed that habitat type and season significantly affected the structure of decapod assemblages, but diel patterns had a minor influence. Among decapod species, Pa. macrodactylus and Pugettia quadridens characterized the decapod assemblages in seagrass beds at the northern semi-closed bay, while Telmessus acutidens, Crangon affinis, Cr. hakodatei, Charybdis (Charybdis) japonica, and Portunus sanguinolentus were significantly associated with both vegetated and unvegetated habitats at the southern exposed bay, with the former two species more abundant during the colder season.

Importance of habitat diversity to changes in benthic metabolism over land-use gradients: evidence from three subtropical estuaries

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 631:31-47 (2019) - DOI: https://doi.org/10.3354/meps13147 Importance of habitat diversity to changes in benthic metabolism over land-use gradients: evidence from three subtropical estuaries Jian-Jhih Chen*, Naomi S. Wells, Dirk V. Erler, Bradley D. Eyre Centre for Coastal Biogeochemistry, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia *Corresponding author: k.chen.15@student.scu.edu.au ABSTRACT: Seasonal rates of benthic gross primary production, net primary production and respiration were measured and whole-system carbon budgets constructed in 3 subtropical estuaries with different catchment land-use intensities to better understand how land-use changes influence benthic metabolism. Annual benthic net ecosystem metabolism (NEM) indicates that systems become more heterotrophic with increasing land-use intensity. This is due to a combination of an increase in the area of unvegetated habitats and the unvegetated habitats becoming more heterotrophic with increasing land-use intensity. Whole-system NEM is closely linked to benthic NEM, highlighting the important control of benthic metabolism on whole-system metabolism in shallow coastal systems. Carbon mass balances show whole-system net metabolism also shifted from net autotrophic to net heterotrophic, with a concomitant switch from CO2 uptake to emission, with increasing land-use intensity. Our findings demonstrate that land-use changes shift whole-estuary metabolism by altering both habitat distribution and within-habitat metabolism rates. KEY WORDS: Estuary · Metabolism · Habitat · Land-use changes · Seagrass · Carbon budget · CO2 emissions · Net ecosystem metabolism Full text in pdf format Supplementary material PreviousNextCite this article as: Chen JJ, Wells NS, Erler DV, Eyre BD (2019) Importance of habitat diversity to changes in benthic metabolism over land-use gradients: evidence from three subtropical estuaries. Mar Ecol Prog Ser 631:31-47. https://doi.org/10.3354/meps13147 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 631. Online publication date: November 21, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Propagule composition regulates the success of an invasive seaweed across a heterogeneous seascape

Abstract Propagule pressure is acknowledged as a key determinant of invasion success. Nonetheless, the role of morphological or physiological attributes of propagules (i.e. their quality) in regulating invader establishment has been little explored. In particular, no study has investigated how the presence of propagules differing in quality within an inoculum influences establishment across heterogeneous landscapes. We experimentally tested the hypothesis that the quality (+Fronds+Rhizoids; +Fronds−Rhizoids; −Fronds+Rhizoids) and the diversity (1, 2 and 3 fragment types) of vegetative fragments of the seaweed Caulerpa taxifolia determine their establishment success across seascapes consisting of bare sediments and patches of the seagrass Zostera muelleri exposed to different disturbance intensities (control, seagrass canopy clipping and total removal). After 6 weeks, seaweed biomass, stolon and frond length, frond and rhizoid number were generally greater in unvegetated habitats (bare sediments and total seagrass removal) than full or reduced seagrass canopies. The type and the diversity of types of fragments inoculated had significant effects on the final biomass and morphological features of C. taxifolia only in vegetated habitats. In control plots, inocula of fragments retaining both fronds and rhizoids achieved higher biomass, developed longer stolons and more fronds. In canopy clipping plots, mixed inocula of +Fronds+Rhizoids and −Fronds+Rhizoids fragments had the greatest biomass and stolon length. Synthesis. Assessing how propagules differing in quality perform in different habitats might be not sufficient to draw a comprehensive picture of invasion risk, as their establishment can be modulated by both negative and positive interactions among them. Propagule composition should be, therefore, considered as a further dimension of propagule pressure. Our results also suggest that the relevance of specific propagule traits for invader establishment decreases from intact to degraded habitats. Considering propagule size in terms of amount of competent propagules, rather than an absolute measure, would refine our ability of predicting invasion risk across habitats differing in biotic or abiotic conditions.

The importance of different juvenile habitats as nursery areas for a ubiquitous estuarine-dependent marine fish species

Estuarine-dependent marine fish species rely on shallow, sheltered and food rich habitats for protection from predators, growth and ultimately recruitment to adult populations. Hence, habitats within estuaries function as critical nursery areas for a variety of fish species. Results from stomach content analysis and dietary diatom composition of a ubiquitous estuarine-dependent species Rhabdosargus holubi (Steindachner, 1881) in the main vegetated and un-vegetated habitats in the Bushmans Estuary, South Africa, were interpreted along with published information on habitat complexity, relative abundance and behaviour of this species. Although the complexity of seagrass, together with the higher abundance and behaviour of R. holubi in seagrass suggests that this is the main nursery habitat (in terms of both feeding and protection from predation), the dominance of red filamentous algae and the presence of some invertebrates mainly in the diet of fish from un-vegetated habitats indicates that this species is using a mosaic of habitats, including un-vegetated areas, for foraging. Based on the above findings, and results from other studies, it is concluded that juvenile R. holubi in permanently open estuaries makes use of a range of habitats according to macrophyte shelter from predators, the availability of preferred food resources and physical drivers such as water depth and tidal phase. This study demonstrated that a multi-method approach, as opposed to a single method approach (diet alone) is useful to assess the nursery value of juvenile fish habitats.

Temporal variation in intertidal habitat use by nekton at seasonal and diel scales

Structure provided by temperate seagrasses is expected to reduce encounter rates with predators and therefore benefit small nekton most in summer, when predation is intense and seagrass reaches peak biomass, and in the day relative to night, when darkness limits visually-oriented predators regardless of habitat. Based on seines in eelgrass (Zostera marina), unvegetated habitat, and edges in Willapa Bay, Washington, USA, nekton abundances varied across habitats and on both diel and seasonal time scales, yet only a few time-by-habitat interactions were observed, in which habitat distinctions were most pronounced at certain times. One explanation is that four of the six most abundant species disproportionately occupied unvegetated habitat or were habitat generalists, but our expectations were based on eelgrass-associated taxa. Multivariate community structure responded separately to season, habitat, and diel period, in order of importance. Total abundance showed a significant season-by-habitat interaction. A summer peak in vegetated habitats was largely driven by shiner perch and sticklebacks, two eelgrass-associated fishes, while unvegetated habitat showed year-round uniform abundances due to taxa like English sole and sand shrimp with winter and spring peaks, and no strong habitat associations or association with unvegetated habitat, respectively. In a single diel-by-habitat interaction, shiner perch were eelgrass-associated during the day but not at night. No evidence emerged of differences in body size across habitats for any species measured, but many taxa grew seasonally, likely as cohorts migrating out of the estuary. Seasonality was thus the strongest signal governing patterns of community structure, abundance, and body size across time and space, while habitat structure and diel period were less important. Our results are largely consistent with the other studies showing the primacy of seasonality in structuring estuarine nekton communities, but also show that this pattern is highly dependent on the seasonal recruitment patterns and habitat associations of abundant nekton.

Characterization of Pacific oyster Crassostrea gigas proteomic response to natural environmental differences

Global climate change is rapidly altering coastal marine ecosystems important for food production. A comprehensive understanding of how organisms will respond to these complex environmental changes can come only from observing and studying species within their natural environment. To this end, the effects of environmental drivers - pH, dissolved oxygen content, salinity, and temperature - on Crassostrea gigas physiology were evaluated in an outplant experiment. Sibling juvenile oysters were outplanted to eelgrass and unvegetated habitat at five different estuarine sites within the Acidification Nearshore Monitoring Network in Washington State, USA to evaluate how regional environmental drivers influenced molecular physiology. We tested the effects environmental conditions at outplant sites and habitat to determine if macrophyte presence and diurnal cycling buffered pH conditions and changed the oysters expressed proteome. A novel, two-step, gel-free proteomic approach was used to identify differences in protein abundance in C. gigas ctenidia tissue after a 29 day outplant by 1) identifying proteins in a data independent acquisition survey step and 2) comparing relative quantities of targeted environmental response proteins using selected reaction monitoring. While there was no difference in protein abundance detected between habitats or within Puget Sound, C. gigas outplanted at Willapa Bay had significantly higher abundances of antioxidant enzymes and carbohydrate metabolism proteins. Environmental factors at Willapa Bay, such as higher average temperature, could have driven this protein abundance pattern. These findings generate a suite of new hypotheses for lab and field experiments to compare the effects of regional conditions on physiological responses of marine invertebrates.

Pacific geoduck (Panopea generosa) resilience to natural pH variation

Pacific geoduck aquaculture is a growing industry, however, little is known about how geoduck respond to varying environmental conditions, or how the industry will fare under projected climate conditions. To understand how geoduck production may be impacted by low pH associated with ocean acidification, multi-faceted environmental heterogeneity needs to be included to understand species and community responses. In this study, eelgrass habitats and environmental heterogeneity across four estuarine bays were leveraged to examine low pH effects on geoduck under different natural regimes, using targeted proteomics to assess physiology. Juvenile geoduck were deployed in eelgrass and adjacent unvegetated habitats for 30 days while pH, temperature, dissolved oxygen, and salinity were monitored. Across the four bays, pH was lower in unvegetated habitats compared to eelgrass habitats. However this did not impact geoduck growth, survival, or proteomic abundance patterns in gill tissue. Temperature and dissolved oxygen differences across all locations corresponded to differences in growth and targeted protein abundance patterns. Specifically, three protein abundance levels (trifunctional-enzyme β-subunit, puromycin-sensitive aminopeptidase, and heat shock protein 90-α) and shell growth positively correlated with dissolved oxygen variability and inversely correlated with mean temperature. These results demonstrate that geoduck may be resilient to low pH in a natural setting, but other abiotic factors (i.e. temperature, dissolved oxygen variability) may have a greater influence on geoduck physiology. In addition this study contributes to the understanding of how eelgrass patches influences water chemistry.

Stabilizing effects of seagrass meadows on coastal water benthic food webs

Seagrass meadows ecosystem engineering effects are correlated to their density (which is in turn linked to seasonal cycles) and often cannot be perceived below a given threshold level of engineer density. The density and biomass of seagrass meadows (Z. marina) together with associated macrophytes undergo substantial seasonal changes, with clear declines in winter. The present study aims to test whether the seasonal changes in the density of recovering seagrass meadows affect the benthic food webs of the southern Baltic Sea (Puck Bay). It includes meiofauna, macrofauna and fish of vegetated and unvegetated habitats in summer and winter seasons. Two levels of organization have been tested – species-specific diet preferences using stable isotopes (δ13C, δ15N) in Bayesian mixing models (MixSIAR) and the community-scale food web characteristics by means of isotopic niches (SIBER). Between-habitat differences were observed for grazers, as a greater food source diversity in species from vegetated habitats was noted in both seasons. Larger between-habitat differences in winter were documented for suspension/detritus feeders. The community-wide approach showed that the differences between the habitats were greater in winter than in summer (as indicated by the lower overlap of the respective isotope niches). Overall, the presence of seagrass meadows increased ecological stability (in terms of the range of food sources utilized by consumers) in the faunal assemblage, while invertebrates from unvegetated areas shifted their diet to cope with winter conditions. Therefore, as a more complex system, not sensitive to seasonal changes, Z. marina meadows create a stable habitat with high resilience potential.

Habitat use patterns and edge effects across a seagrass-unvegetated ecotone depend on species-specific behaviors and sampling methods

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 598:21-33 (2018) - DOI: https://doi.org/10.3354/meps12609 Habitat use patterns and edge effects across a seagrass-unvegetated ecotone depend on species-specific behaviors and sampling methods Collin Gross1,3,*, Cinde Donoghue2, Casey Pruitt2, Jennifer L. Ruesink1 1Department of Biology, University of Washington, Seattle, Washington 98195-1800, USA 2Aquatic Assessment and Monitoring Team, Washington Department of Natural Resources, Aquatics Division, Olympia, Washington 98504, USA 3Present address: Department of Evolution and Ecology and Center for Population Biology, University of California, Davis, California 95616, USA *Corresponding author: colgross@ucdavis.edu ABSTRACT: Although habitat edges can be areas of elevated richness and intense ecological interactions, results from studies of mesopredators in seagrass ecosystems are equivocal, with some communities sensitive to the mere presence of seagrass, while others respond specifically to edges and landscape structure. We attempted to address these discrepancies through a species-specific lens, investigating patterns in aggregate and per-taxon mesopredator densities and behaviors across a seagrass-unvegetated ecotone at 3 sites in Washington State, USA, with special focus on patterns apparent on edges. Aggregate abundance was enhanced inside eelgrass (in seines) and on edges (in videos) relative to unvegetated habitats, a difference attributed to the abilities of the 2 methods to sample dominant taxa in different habitats. Both methods concurred that structure-association primarily occurred for pelagic, not benthic taxa. Videos suggested that shiner perch and stickleback moved more slowly in eelgrass interiors relative to unvegetated habitat, that stickleback fed more frequently in interior habitat, and that habitat use did not differ between low and high water. Eelgrass appears to disproportionately benefit small pelagic taxa rather than benthic species, but no distinct responses to edges were detected for the distribution or behavior of dominant taxa. Overall, responses to structure were taxon-specific, and for most taxa, shoot structure seemed more important than landscape structure for distribution and behavior. Our results suggest that the wide variation in community responses to landscape structure found in the literature may result from differences in local species pools, and the ability of sampling gear to detect specific taxa in different habitats. KEY WORDS: Edge effect · Seagrass · Mesopredators · Method comparison · Species-specific responses · Landscape ecology Full text in pdf format Supplementary material PreviousNextCite this article as: Gross C, Donoghue C, Pruitt C, Ruesink JL (2018) Habitat use patterns and edge effects across a seagrass-unvegetated ecotone depend on species-specific behaviors and sampling methods. Mar Ecol Prog Ser 598:21-33. https://doi.org/10.3354/meps12609 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 598. Online publication date: June 28, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Seagrass fish assemblages in the Namhae Island, Korea: The influences of seagrass vegetation and biomass

Seagrass habitats are highly productive areas that support vegetative habitats and provide shelter for various marine animals. In seagrass beds, vegetation patterns are important factors that control faunal assemblage structure. In this study, we surveyed fish assemblage structures in Zostera marina beds and in adjacent unvegetated habitats to assess the influences of seagrass vegetation and biomass on fish assemblage structures. In total, fifty-four fish species belonging to 30 families were collected using a small beam trawl at both seagrass beds and unvegetated habitats from two different areas off the coast of Namhae Island, South Korea. The dominant fish species in seagrass beds were Sebastes inermis and Rudarius ercodes, whereas Acanthogobius flavimanus and Takifugu niphobles were the most abundant fish species in unvegetated habitats. The number of species, their abundance, and the diversity of fish assemblages varied greatly by habitat type, study site, and season. Abundance peaked in seagrass beds and during the spring, and were lowest catch rate in unvegetated habitats and during the winter months. Multivariate analyses revealed that habitat type, site, and season affected the structure of fish assemblages. Seagrass vegetation supported higher densities and greater fish species richness, but not species diversity. Among the dominant species, Lateolabrax japonicus, Sebastes schlegelii, Syngnathus schlegeli, and Rudarius ercodes characterized the fish assemblages in seagrass beds, with the former two more abundant under conditions of higher seagrass biomass. Gobiid species were significantly correlated with unvegetated habitats.

Seasonal and habitat structures of crustacean decapod assemblages associated withZostera marinabeds in northern Jinhae Bay, Korea

Crustacean decapod assemblages were surveyed inZostera marinabeds adjacent to tidal flats (ET) and rocky shore (ER), and in unvegetated habitats (UV). Decapod samples were collected monthly throughout 2002 using a small beam trawl from northern Jinhae Bay, Korea. Water temperature, salinity, eelgrass biomass, sediment composition and organic matter were also monitored to assess any correlation between environmental variables and decapod fauna. A total of 31 decapod species belonging to five taxa (three prawns, 13 caridean shrimps, one hermit crab, one mud shrimp and 13 crabs) were collected at three different habitats. To assess variations in decapod assemblages in relation to habitat type and season, various multivariate analyses were used. The dominant caridean shrimps werePalaemon macrodactylus, Alpheus digitalisandCrangon uritai,and the dominant crabs wereCharybdis japonica, Hemigrapsus penicillatusandCharybdis bimaculata. The number, abundance and diversity of decapod species varied greatly with habitat type and season, peaking in eelgrass beds and during spring, and showing the lowest catch rate in unvegetated habitat and during winter months. The nMDS ordination and multivariate analyses revealed that habitat type and season were determinant factors affecting the structure of decapod assemblages. Seasonal shifts in the abundance of decapods corresponded with changes in eelgrass biomass and loss on ignition (LOI), but not with water temperature or salinity.

Benthic macrofaunal structure and secondary production in tropical estuaries on the Eastern Marine Ecoregion of Brazil.

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.

Seagrass corridors and tidal state modify how fish use habitats on intertidal coral reef flats

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 581:135-147 (2017) - DOI: https://doi.org/10.3354/meps12311 Seagrass corridors and tidal state modify how fish use habitats on intertidal coral reef flats Jean P. Davis1,2,*, Kylie A. Pitt1, Andrew D. Olds1,3, Alastair R. Harborne4,5, Rod M. Connolly1 1Australian Rivers Institute - Coast and Estuaries, and Griffith School of Environment, Griffith University, Gold Coast, QLD 4222, Australia 2California Department of Fish and Wildlife, Marine Region, Los Alamitos, CA 90720, USA 3School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD 4558, Australia 4Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA 5Marine Spatial Ecology Laboratory and Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia *Corresponding author: jeanpepper@gmail.com ABSTRACT: Identifying pathways that animals use to move among ecosystems has become a focus for improving conservation planning. The function of habitat corridors in facilitating animal movement among terrestrial ecosystems is well established. By contrast, the role of habitat corridors for the movement of marine animals is poorly understood. We used underwater video cameras to evaluate the effects of seagrass corridors and water depth on fish abundance, and the arrival of prey and predatory species on intertidal coral reef flats in eastern Australia. Cameras were placed in intertidal seagrass and unvegetated habitats during incoming tides and recorded fish that moved across these habitats. We found some evidence that fish were more abundant over intertidal seagrass, particularly garfish Hyporhamphus regularis ardelio, striped barracuda Sphyraena obtusata and striped grunter Pelates sexlineatus, but most species did not appear to use the intertidal seagrass as a corridor. Prey fish were generally more abundant at shallower water depths, whereas predators were more common in deeper water, but many species were present over intertidal flats throughout the incoming tide. Our findings show that the movement of fishes across intertidal flats is dynamic, and depends on the species of interest, the composition of intertidal seascapes and tidal condition. Understanding how biotic and abiotic factors interact to influence fish movement and shape patterns in habitat use is a critical challenge for conservation planning in shallow coral reef seascapes. KEY WORDS: Habitat corridor · Predation refuge · Underwater video · Mangrove Full text in pdf format Supplementary material PreviousNextCite this article as: Davis JP, Pitt KA, Olds AD, Harborne AR, Connolly RM (2017) Seagrass corridors and tidal state modify how fish use habitats on intertidal coral reef flats. Mar Ecol Prog Ser 581:135-147. https://doi.org/10.3354/meps12311 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 581. Online publication date: October 13, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Role of habitats and sampling techniques on macroinvertebrate descriptors and ecological indicators: An experiment in a protected Mediterranean lagoon

Macroinvertebrates are commonly applied for ecological investigations and as ecological indicators. However, the role of the sampling technique, effort and habitat on macroinvertebrate descriptors, diversity indices and ecological indicators in transitional water ecosystems is little known yet. This research aims to evaluate the influence of sampling techniques on macroinvertebrate assemblages and ecological indicators comparing box-corer and litterbag techniques, in prairie and unvegetated habitats. The experiment was conducted in a protected Mediterranean shallow lagoon dominated by marine water input. Three types of litterbags were prepared with: i. Phragmites australis dry leaves (terrestrial input); ii. Posidonia oceanica dry leaves (marine input), and iii. an equal mixture of both leaves. Three replicates of box-corer samples were collected in two sites per habitat, litterbags were submerged and retrieved after 30days. Macroinvertebrate abundance, species richness, diversity indices and ecological indicators were measured and compared among sampling techniques and between habitats. Macroinvertebrate data was then pooled, analysed and compared to each single technique. Twenty-seven species were sampled overall, 4 species overlapped between box-corer and litterbags, 6 species (26%) were exclusive to the box-corer and 16 species (59%) were caught using only litterbags. Species diversity in litterbags was always higher than in box-corer, but macroinvertebrate assemblages were described better when using data pooled. In prairie, the ecological indicators varied significantly between the data pooled and separate sampling technique. Finally, this research highlights the relevance of using more than one sampling technique to obtain a better description of macroinvertebrate assemblages and the ecological status of Mediterranean lagoons.