Changes In Benthic Habitats Research Articles

Assessing the spatial distribution of meiofaunal communities in Krossfjord, Svalbard Archipelago: Foraminifera diversity as a key component

The study furnishes an insight into the ecology of meiofauna through an elaborate examination of the living Foraminifera in the Krossfjorden system of the Svalbard Archipelago. Samples collected during the Summer Phase Indian Arctic Expeditions of 2017 and 2018 were analyzed to reveal novel insights into the distribution, abundance and species composition of living Foraminifera in this less studied fjord system. The investigation uncovered a rich and diverse meiofaunal community consisting of ten taxonomic groups, among which living Foraminifera emerged as a prominent component. The spatial patterns of Foraminifera distribution were examined, revealing their preferences for specific habitats and environmental conditions within the Krossfjorden system. The Shannon diversity index (H’) indicates good overall diversity of foraminifera in the Krossfjord region, with H’ ranging from 4.49 to 4.891 in 2017 and from 3.885 to 4.984 in 2018. The research discovered noteworthy inequalities in the distribution of Foraminifera species amid inner and outer stations, as inferred by PERMANOVA analysis (p<0.05). The foraminiferan species Nonionellina labradorica was the dominant species in outer, middle and inner zones in the fjord, while species Lobatula lobatula, Quinqueloculina seminulum, Hormosinella sp., and Procerolagena sp. played significant roles in driving the dissimilarity between outer, middle, and inner zones. Environmental factors accounted for a substantial 83.1% of the variations observed in foraminiferan species distribution across four CCA axes. The fluctuations in potential temperature, sand fraction, chlorophyll-a, C:N ratio, organic matter, and salinity have had a noteworthy effect on the distribution of species. These findings underscore the susceptibility of Foraminifera and the broader meiofaunal community to the impacts of environmental variations in this rapidly changing Arctic ecosystem. The outcomes of this research provide a crucial baseline for understanding the ecological dynamics of meiofaunal communities in the Krossfjorden system, contributing to predicting future changes in benthic habitats, including the potential repercussions for meiobenthic productivity.

Habitat development and species arrival drive succession of the benthic invertebrate community in restored urban streams

BackgroundUrban streams are characterised by species-poor and frequently disturbed communities. The recovery of heavily polluted urban streams is challenging but the simple community structure makes recolonisation patterns more transparent. Therefore, they are generally applicable model systems for recolonisation of restored streams. Principal questions of stream restoration concern the drivers and patterns of recolonisation processes. Rarely, recolonisation of restored streams is recorded for a sufficient time to observe patterns of habitat and community development in detail. Over 10 years, we monitored benthic habitat changes and macroinvertebrate communities of eight restored sites in an urban stream network that was formerly used as an open sewer and thus, almost uninhabitable for macroinvertebrates prior to restoration. We analysed changes in environmental variables and communities with a selection of multi-variate analyses and identified indicator species in successional stages.ResultsProportions of stony substrate and conductivity decreased over time since restoration, while the riparian vegetation cover increased along with the amount of sandy substrate. The communities fluctuated strongly after restoration but began to stabilise after around eight years. TITAN analysis identified 9 species, (e.g. the mayfly Cloeon dipterum and the beetle Agabus didymus), whose abundances decreased with time since restoration, and 19 species with an increasing abundance trend (e.g. several Trichopteran species, which colonised once specific habitats developed). Woody riparian vegetation cover and related variables were identified as major driver for changes in species abundance. In the last phase of the observation period, a dry episode resulted in complete dewatering of some sites. These temporarily dried sections were recolonised much more rapidly compared to the recolonisation following restoration.ConclusionsOur results underline that community changes following urban stream restoration are closely linked to the evolving environmental conditions of restored streams, in particular habitat availability initialised by riparian vegetation. It takes about a decade for the development of a rich and stable community. Even in streams that were almost completely lacking benthic invertebrates before restoration, the establishment of a diverse macroinvertebrate community is possible, underlining the potential for habitat restoration in formerly heavily polluted urban areas.

Artificial hard-substrate colonisation in the offshore Hywind Scotland Pilot Park

Abstract. Artificial substrates associated with renewable offshore energy infrastructure, such as floating offshore wind farms, enable the establishment of benthic communities with a taxonomic composition similar to that of naturally occurring rocky intertidal habitats. The size of the biodiversity impact and the structural changes in benthic habitats will depend on the selected locations. The aim of the study is to assess colonisation and zonation, quantify diversity and abundance, and identify any non-indigenous species present within the wind farm area, as well as to describe changes in the epifouling growth between 2018 and 2020, with regards to coverage and thickness. This article is based on work undertaken within the offshore floating Hywind Scotland Pilot Park, the first floating offshore wind park established in the world, located approximately 25 km east of Peterhead, Scotland. The floating pilot park is situated in water depths of approximately 120 m, with a seabed characterised predominantly by sand and gravel substrates with occasional patches of mixed sediments. The study utilised a work class remotely operated vehicle with a mounted high-definition video camera, deployed from the survey vessel M/V Stril Explorer. A total of 41 structures, as well as their associated sub-components, including turbines substructures, mooring lines, suction anchors and infield cables, were analysed with regards to diversity, abundance, colonisation, coverage and zonation. This approach provides comprehensive coverage of whole structures in a safe and time-saving manner. A total of 11 phyla with 121 different taxa were observed, with macrofauna as well as macroalgae and filamentous algae being identified on the different structures. The submerged turbines measured approximately 80 m in height and exhibited distinct patterns of zonation. Plumose anemones (Metridium senile) and tube-building fan worms (Spirobranchus sp.) dominated the bottom and mid-sections (80–20 m) of the turbines, while kelp and other Phaeophyceae with blue mussels (Mytilus spp.) dominated top sections of the turbines (20–0 m). A general increase in the coverage of the epifouling growth between 2018 and 2020 was observed, whereas the change in thickness between years was more variable.

Offshore Wind Energy and Benthic Habitat Changes: Lessons from Block Island Wind Farm

Study concepts, oversight, and funding for the RODEO Program were provided by the US Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program, Washington, DC, under HDR’s IDIQ Contract No. M15P2.

Decadal-scale response of detritivorous surgeonfishes (family Acanthuridae) to no-take marine reserve protection and changes in benthic habitat.

No-take marine reserves (NTMR) are increasingly being implemented to mitigate the effects of fishing on coral reefs, yet determining the efficacy of NTMRs depends largely on partitioning the effects of fishing from the effect of benthic habitat. Species of coral-reef fishes typically decline in density when subjected to fishing or benthic disturbances, but this is not always the case. This study documents the long-term (8-31 years) response of six species of detritivorous surgeonfishes (family Acanthuridae) to NTMR protection and benthic habitat change at four islands (Apo, Sumilon, Mantigue, Selinog) in the central Philippines, each island with a NTMR and a monitored fished site. Despite being subject to moderate fishing pressure, these species did not increase in density with NTMR protection. However, density of these surgeonfishes had a strong negative relationship with cover of live hard coral and a strong positive relationship with cover of dead substratum (sand, rubble, hard dead substratum). These surgeonfishes typically feed over dead substrata and thus probably increase in density following large environmental disturbances that substantially reduce live hard coral cover. Here, we describe effects of environmental disturbance events (e.g., use of explosives, typhoons) that reduced live hard-coral cover and subsequent large increases (up to 25 fold) in surgeonfish densities, which then slowly (over 5-15 years) decreased in density as live hard coral recovered. Density of these functionally important surgeonfish species was influenced more by changes to benthic cover than by NTMR protection. Thus, we highlight the greater importance of bottom-up controls (i.e., benthic changes to food availability) than top-down control (i.e., fishing) on a functionally important group of coral-reef fishes.

Long-Term Monitoring Data Provide Evidence of Declining Species Richness in a River Valued for Biodiversity Conservation

Abstract Free-flowing river segments provide refuges for many imperiled aquatic biota that have been extirpated elsewhere in their native ranges. These biodiversity refuges are also foci of conservation concerns because species persisting within isolated habitat fragments may be particularly vulnerable to local environmental change. We have analyzed long-term (14- and 20-y) survey data to assess evidence of fish species declines in two southeastern U.S. rivers where managers and stakeholders have identified potentially detrimental impacts of current and future land uses. The Conasauga River (Georgia and Tennessee) and the Etowah River (Georgia) form free-flowing headwaters of the extensively dammed Coosa River system. These rivers are valued in part because they harbor multiple species of conservation concern, including three federally endangered and two federally threatened fishes. We used data sets comprising annual surveys for fish species at multiple, fixed sites located at river shoals to analyze occupancy dynamics and temporal changes in species richness. Our analyses incorporated repeated site-specific surveys in some years to estimate and account for incomplete species detection, and test for species-specific (rarity, mainstem-restriction) and year-specific (elevated frequencies of low- or high-flow days) covariates on occupancy dynamics. In the Conasauga River, analysis of 26 species at 13 sites showed evidence of temporal declines in colonization rates for nearly all taxa, accompanied by declining species richness. Four taxa (including one federally endangered species) had reduced occupancy across the Conasauga study sites, with three of these taxa apparently absent for at least the last 5 y of the study. In contrast, a similar fauna of 28 taxa at 10 sites in the Etowah River showed no trends in species persistence, colonization, or occupancy. None of the tested covariates showed strong effects on persistence or colonization rates in either river. Previous studies and observations identified contaminants, nutrient loading, or changes in benthic habitat as possible causes for fish species declines in the Conasauga River. Our analysis provides baseline information that could be used to assess effectiveness of future management actions in the Conasauga or Etowah rivers, and illustrates the use of dynamic occupancy models to evaluate evidence of faunal decline from time-series data.

Off‐reef planktivorous reef fishes respond positively to decadal‐scale no‐take marine reserve protection and negatively to benthic habitat change

AbstractThe effects of no‐take marine reserve (NTMR) protection and changes in benthic habitat on fusiliers (family Caesionidae) were investigated at four small Philippine offshore islands on time scales of 10–31 years. Fusiliers are highly mobile, schooling, medium‐sized planktivorous fish that generally feed “off‐reef.” For these reasons, and given the small size of the NTMRs (3.6–37.5 ha) in this study, it was predicted that fusilier density would be unlikely to show clear effects of NTMR protection, or to respond to changes in benthic habitat. In contrast to predictions, clear NTMR effects were observed on fusilier density at three of the four NTMRs, with durations of protection from 14 to 31 years. Furthermore, the study provided strong evidence that benthic variables, specifically cover of live hard coral and dead substratum, affect the density of fusiliers. This effect of benthic habitat on density was highlighted by several major environmental disturbances that caused shifts in the benthic habitat from live hard coral to dead substratum. For two of the three most abundant species of fusiliers individually, and for all three of them combined (Pterocaesio pisang + Caesio caerulaurea + Pterocaesio digramma/tessellata), as live hard coral cover decreased, fish density decreased. It is hypothesized that these “off‐reef” daytime feeders may have such a strong association with live hard coral cover because they use this habitat as nocturnal sleeping sites. Multivariate analyses indicated that, across all sites and times sampled, cover of live hard coral and dead substratum accounted for 38% of the variation in fish assemblage structure. These results are important as there are very few reports in the published literature of strong effects of NTMR protection or changes in benthic habitat on the density and assemblage structure of fusiliers.

Decadal-scale effects of benthic habitat and marine reserve protection on Philippine goatfish (F: Mullidae)

Reef fish populations can be affected by both fishing and changes in benthic habitat. Yet, partitioning these effects is often difficult, usually requiring an appropriate sampling design and long-term monitoring. Here we quantify, over a 30-yr period, the effects of benthic habitat change and no-take marine reserve (NTMR) protection on the density and species richness of a lightly harvested benthic-feeding reef fish family, the Mullidae (goatfish), at four Philippine islands. Boosted regression trees demonstrated that goatfish density and species richness had strong negative associations with hard coral cover and strong positive associations with cover of dead substratum. No-take marine reserve protection had no effect on the density or species richness of goatfish over 19 and 30 yr at Sumilon and Apo islands, respectively. However, environmental disturbances (e.g., typhoons, coral bleaching) that reduced hard coral cover subsequently led to increases in goatfish numbers for periods ranging from 2 to 8 yr. After initial increases due to benthic disturbance, goatfish populations decreased during coral recovery, occurring on timescales of 10–20 yr. This long-term, “natural experiment” demonstrated that changes to benthic habitat (bottom-up control) had a far greater effect on Philippine goatfish populations than protection from fishing (a top-down effect) in NTMRs. Given the strong positive response of goatfish populations to loss of live hard coral cover, this group of fishes may be a valuable indicator species for habitat degradation on coral reefs.

Reconstructing diatom and chironomid assemblages to infer environmental spatiotemporal trends within Lake Diefenbaker, a narrow river-valley reservoir on the Canadian Prairies

Lake Diefenbaker (Saskatchewan, Canada) is a large reservoir in the southern Canadian Prairies. However, limited monitoring data were available to assess long-term trends in environmental quality. Therefore, a paleolimnological study was conducted to investigate temporal trends in the trophic status of the reservoir. Sediment cores were collected along the length of Lake Diefenbaker, and sediment subsections were analyzed for sub-fossil remains of diatoms and chironomid larvae. The compositions of diatom and chironomid communities were consistent over approximately the previous decade at up-reservoir locations, with a meso-eutrophic species, Stephanodiscus parvus, dominating the diatom communities. This taxon also dominated the early down-reservoir diatom communities along the main flow of the reservoir. However, during the 1980s, dominance of the diatom assemblage shifted from S. parvus to a combination of Aulacoseira ambigua and Tabellaria flocculosa in the majority of down-reservoir regions. Based on total phosphorus concentration optima for these species, this shift suggests a reduction in total phosphorus both spatially and temporally. However, these observed shifts could also have been due to increased water clarity or changes to thermal stratification regime both spatially (from up- to down-reservoir) and over time down-reservoir. An increase in relative abundance of the chironomid tribe Tanytarsini, both with distance down-reservoir and over time, was likely due to spatial and temporal changes in benthic habitat (i.e., sediment character). Results highlight the need to interpret temporal trends within the context of spatial gradients in physical processes, chemistry, and biology along the longitudinal axis of narrow river valley reservoirs.

Habitat dynamics, marine reserve status, and the decline and recovery of coral reef fish communities

Severe climatic disturbance events often have major impacts on coral reef communities, generating cycles of decline and recovery, and in some extreme cases, community-level phase shifts from coral-to algal-dominated states. Benthic habitat changes directly affect reef fish communities, with low coral cover usually associated with low fish diversity and abundance. No-take marine reserves (NTRs) are widely advocated for conserving biodiversity and enhancing the sustainability of exploited fish populations. Numerous studies have documented positive ecological and socio-economic benefits of NTRs; however, the ability of NTRs to ameliorate the effects of acute disturbances on coral reefs has seldom been investigated. Here, we test these factors by tracking the dynamics of benthic and fish communities, including the important fishery species, coral trout (Plectropomus spp.), over 8 years in both NTRs and fished areas in the Keppel Island group, Great Barrier Reef, Australia. Two major disturbances impacted the reefs during the monitoring period, a coral bleaching event in 2006 and a freshwater flood plume in 2011. Both disturbances generated significant declines in coral cover and habitat complexity, with subsequent declines in fish abundance and diversity, and pronounced shifts in fish assemblage structure. Coral trout density also declined in response to the loss of live coral, however, the approximately 2:1 density ratio between NTRs and fished zones was maintained over time. The only post-disturbance refuges for coral trout spawning stocks were within the NTRs that escaped the worst effects of the disturbances. Although NTRs had little discernible effect on the temporal dynamics of benthic or fish communities, it was evident that the post-disturbance refuges for coral trout spawning stocks within some NTRs may be critically important to regional-scale population persistence and recovery.

Measuring nearshore variability in benthic environments: An acoustic approach

Hardbottom and sedimentary habitats in the nearshore are continually affected by natural and anthropogenic disturbances. Currently used monitoring practices rely on visual techniques, aerial and underwater photography, which are conducted on an annual basis. These practices do not allow for rigorous assessment of the effects of human-induced or natural events on the distribution and composition of these habitats. We investigated the use of an acoustic ground discrimination system (RoxAnn) to determine changes in benthic habitats in the nearshore area of northern Indian River County, FL where hardbottom outcrops occur. It was determined that this method was precise and repeatable when deployed in a highly variable surf zone environment. Multiple surveys assessed temporal and spatial changes in bottom types. Spatial distributions of several bottom types were identified: bare rock surfaces, Sabellarid worm reef, sponge covered rock, and rock covered with two dominant algal species. Short-term (weekly) changes in the distribution of sand coverage were detected during a relatively calm hydrodynamic period. At one site (R-15), there was an increase of 11% in sediments, which attributed to approximately 2 750 m2 of coverage; 2.1 km south (R-22) there was a 6% decrease in sediments in six days. The latter equates to a change of almost 1 500 m2 of available habitat. These results suggest that the current practice of annual surveying is limited for assessing the magnitude and impact of episodic disturbances on benthic habitats. Based on these data, acoustic ground discrimination systems provide an unbiased, technology-based data collection method to distinguish benthic habitats in the surf zone. Employing this method will benefit researchers and coastal resource managers.

Detecting patterns of change in benthic habitats by acoustic remote sensing

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 477:1-13 (2013) - DOI: https://doi.org/10.3354/meps10264 FEATURE ARTICLE Detecting patterns of change in benthic habitats by acoustic remote sensing A. Rattray1, D. Ierodiaconou1,*, J. Monk1, V. L. Versace2, L. J. B. Laurenson1 1School of Life and Environmental Sciences, Faculty of Science and Technology, and 2University Department of Rural Health, Deakin University, Greater Green Triangle, Warrnambool, Victoria 3280, Australia *Corresponding author. Email: iero@deakin.edu.au ABSTRACT: Changes in benthic habitats occur as a result of natural variation or human-induced processes. It is important to understand natural fine-scale inter-annual patterns of change to separate these signals from patterns of long-term change. Describing change from an acoustic remote sensing standpoint has been facilitated by the recent availability of full coverage swath acoustic datasets, but is limited by cost pressures associated with multiple surveys of the same area. We studied the use of landscape transition analysis as a means to differentiate seemingly random patterns of habitat change from systematic signals of habitat transition at a shallow (10 to 50 m depth) 18 km2 site on the temperate Australian continental shelf in 2006 and 2007. Supervised classifications for each year were accomplished using independently collected high-resolution swath acoustic and video reference data. Of the 4 representative biotic classes considered, signals of directional systematic changes occurred between a kelp-dominated class, a sessile invertebrate-dominated class and a mixed class of kelp and sessile invertebrates. We provide a detailed analysis of the components of the traditional change detection cross tabulation matrix, allowing identification of the strongest signals of systematic habitat transitions. Identifying patterns of habitat change is an important first step toward understanding the processes that drive them. KEY WORDS: Multibeam sonar · Kelp · Video · Monitoring · Habitat mapping Full text in pdf format Information about this Feature Article NextCite this article as: Rattray A, Ierodiaconou D, Monk J, Versace VL, Laurenson LJB (2013) Detecting patterns of change in benthic habitats by acoustic remote sensing. Mar Ecol Prog Ser 477:1-13. https://doi.org/10.3354/meps10264 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 477. Online publication date: March 12, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Late Quaternary paleoceanography of the Eurasian Basin, Arctic Ocean

We reconstructed late Quaternary deep (3000–4100 m) and intermediate depth (1000–2500 m) paleoceanographic history of the Eurasian Basin, Arctic Ocean from ostracode assemblages in cores from the Lomonosov Ridge, Gakkel Ridge, Yermak Plateau, Morris Jesup Rise, and Amundsen and Makarov Basins obtained during the 1991 Polarstern cruise. Modern assemblages on ridges and plateaus between 1000 and 1500 m are characterized by abundant, relatively species‐rich benthic ostracode assemblages, in part, reflecting the influence of high organic productivity and inflowing Atlantic water. In contrast, deep Arctic Eurasian basin assemblages have low abundance and low diversity and are dominated by Krithe and Cytheropteron reflecting faunal exchange with the Greenland Sea via the Fram Strait. Major faunal changes occurred in the Arctic during the last glacial/interglacial transition and the Holocene. Low‐abundance, low‐diversity assemblages from the Lomonosov and Gakkel Ridges in the Eurasian Basin from the last glacial period have modern analogs in cold, low‐salinity, low‐nutrient Greenland Sea deep water; glacial assemblages from the deep Nansen and Amundsen Basins have modern analogs in the deep Canada Basin. During Termination 1 at intermediate depths, diversity and abundance increased coincident with increased biogenic sediment, reflecting increased organic productivity, reduced sea‐ice, and enhanced inflowing North Atlantic water. During deglaciation deep Nansen Basin assemblages were similar to those living today in the deep Greenland Sea, perhaps reflecting deepwater exchange via the Fram Strait. In the central Arctic, early Holocene faunas indicate weaker North Atlantic water inflow at middepths immediately following Termination 1, about 8500–7000 year B.P., followed by a period of strong Canada Basin water overflow across the Lomonosov Ridge into the Morris Jesup Rise area and central Arctic Ocean. Modern perennial sea‐ice cover evolved over the last 4000–5000 years. Late Quaternary faunal changes reflect benthic habitat changes most likely caused by changes in the import of cold, deepwater of Greenland Sea origin and warmer and middepth Atlantic water to the Eurasian Basin through the Fram Strait, and export of Arctic Ocean deepwater.Appendix Tables Al‐A4 are available on microfiche. Orderfrom the American Geophysical Union, 2000 Florida Avenue,N.W., Washington, DC 20009. Document P94‐002; $2.50.Payment must accompany order.

Sewage sludge disposal and winter flounder, red hake, and american lobster feeding in the New York Bight

Little is known of the effects of sewage sludge disposal on fish and shellfish feeding. This paper presents the results of a 39-month study on the effects of sewage sludge disposal and its abatement on feeding of three species in the New York Bight. Feeding variables were measured in winter flounder, red hake and American lobster at three sites along a gradient of sludge influence. Post-abatement changes in benthic habitats included reduced sediment total organic carbon (TOC) and metal contamination, and increased summer bottom water dissolved oxygen (DO) and changes in the abundances of some benthic infaunal species at the study sites. Statistically significant diet changes were only evident in winter flounder, however. The limited sample sizes and relatively high variability of the results for red hake and lobster gave the tests on the percentage of empty stomachs a relatively low power (1− β = < 0·20) for detection of change, or greater than 80% chance of incorrectly accepting the null hypothesis at a 95% confidence limit (and detectable effect size) even with percentage of empty stomach changes of up to 52% for these two species. There were, however, changes in the frequency of occurrence of certain artifacts or minor, pollution-sensitive prey in the diets that can be associated with sludge disposal abatement. The importance of these changes to predator health was not assessed.