Effects of urbanisation on the parasitoid community of a leafminer

Urbanisation may have detrimental effects on communities of parasitoids, affecting their species richness, abundance, and species dominance. Here we investigated the influence of the degree of urbanisation on parasitoid communities of Liriomyza commelinae (Frost) (Diptera: Agromyzidae), a leafminer of Commelina erecta L. (Commelinaceae), in the city of Córdoba, Argentina. To study changes in species richness, the specific composition of parasitic complexes and their degree of impact on the leafminer, 18 sampling sites from the centre to the outskirts of the city were selected and different variables indicative of urbanisation were quantified in each site. During January and February of 2005 and 2006, all mined leaves found in each plant patch were collected and the following variables were estimated: proportion of mined patches, abundance of the leafminer, total parasitoid species richness, total parasitism rates and parasitism due to the most abundant parasitoid species. The percentage of mined patches and leafminer abundance increased with urbanisation degree. Estimates of parasitoid species richness were not influenced by urbanisation degree but increased with species richness of mined plants. Changes in the specific composition of species along the urbanisation gradient were observed. Although parasitism by one of the species studied was higher in more urbanised sites of the city, the total parasitism rate of L. commelinae was not affected by urbanisation degree, species richness of mined plants or leafminer abundance. It appears that urbanisation benefits the herbivore species here studied but not through altering parasitoid activity. Changes in parasitoid community composition reflex dissimilar tolerance to environmental conditions displayed by different parasitoid species.     

Urban densification causes the decline of ground-dwelling arthropods

Urban densification is often considered has a green planning policy. However, its effects on woodland arthropods have been rarely analysed. To fill this gap, a multi-taxa approach using three ground-dwelling arthropod assemblages was conducted on 11 woodlands located along an urbanisation gradient. The gradient range from rural areas to one of the most urbanized cities in the world: Paris (France). Spiders, ground beetles and rove beetles were sampled with pitfall traps. We addressed the two following questions: (i) do the responses to urbanisation differ between taxa and/or between trait groups (habitat affinity to woodlands and dispersal capability) along the gradient? (ii) do the richness and abundance show a linear or an intermediate response? Our results showed a replacement of forest and non-flying species by generalist species and flying species with an increasing level of urbanisation. In term of species richness and abundance, the response varied between taxonomical and also trait groups. Some groups showed a strong linear decrease like forest carabids but other groups like spiders showed maximum values at intermediate levels of urbanisation. However, after a threshold of 70 % of built-in area, urbanisation negatively affected the species richness of all taxa and almost all trait groups, with a stronger effect on forest species. We suggest that the urban densification strongly impacted the assemblages of ground-dwelling arthropods by modifying both landscape and local properties of woodlands. To be considered as a green planning policy, the deleterious effects of urban densification should be mitigated.     

Spider communities in urban green patches and their relation to local and landscape traits

Urbanization and urban landscape characteristics greatly alter plant and animal species richness and abundances in negative and positive directions. Spiders are top predators, often considered to be sensitive to habitat alteration. Studies in urban environments frequently focus on ground-dwelling spiders or on spiders in built structures, leaving aside foliage spiders. Effects of habitat, landscape type and structure and local characteristics on spider species composition, richness and relative abundance were evaluated in urban green patches in a temperate city of South America. We also assess whether Salticidae could be an indicator group for the broader spider community in the urban environment. Spiders were sampled with a G-VAC (aspirator) in urban green patches in Córdoba city, Argentina, in urban, suburban and exurban habitats (18 sites; six per habitat) and local and landscape traits were assessed. Overall, the exurban was richer than the urban habitat, however, at the site level Salticidae richness and abundance (but not the total spider assemblage) were significantly lower in urban sites. Species composition moderately differed between urban and exurban sites. Results indicate that on urban green spaces a low impervious surface cover, a coverage of trees, herbaceous vegetation and a vertical structure of vegetation at least up to 1 m in height contribute to higher richness and abundance of spiders, Salticidae being more sensitive than the overall spider community to local effects. In addition, Salticidae richness can predict 74% of the total spider richness recorded and may be used as spider diversity bio-indicators in this climatic region.     

Where is the UK's pollinator biodiversity? The importance of urban areas for flower-visiting insects

Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km²) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.     

Contemporary Land Change Alters Fish Communities in a San Francisco Bay Watershed,California, U.S.A.

Urbanization is one of the leading threats to freshwater biodiversity, and urban regions continue to expand globally. Here we examined the relationship between recent urbanization and shifts in stream fish communities. We sampled fishes at 32 sites in the Alameda Creek Watershed, near San Francisco, California, in 1993–1994 and again in 2009, and we quantified univariate and multivariate changes in fish communities between the sampling periods. Sampling sites were classified into those downstream of a rapidly urbanizing area (“urbanized sites”), and those found in less impacted areas (“low-impacted sites”). We calculated the change from non-urban to urban land cover between 1993 and 2009 at two scales for each site (the total watershed and a 3km buffer zone immediately upstream of each site). Neither the mean relative abundance of native fish nor nonnative species richness changed significantly between the survey periods. However, we observed significant changes in fish community composition (as measured by Bray-Curtis dissimilarity) and a decrease in native species richness between the sampling periods at urbanized sites, but not at low-impacted sites. Moreover, the relative abundance of one native cyprinid (Lavinia symmetricus) decreased at the urbanized sites but not at low-impacted sites. Increased urbanization was associated with changes in the fish community, and this relationship was strongest at the smaller (3km buffer) scale. Our results suggest that ongoing land change alters fish communities and that contemporary resurveys are an important tool for examining how freshwater taxa are responding to recent environmental change.     

Importance of scale,land‐use,and stream network properties for riparian plant communities along an urban gradient

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Changes in carabid beetle assemblages across an urban-rural gradient in Japan

As part of the international Globenet project, carabid beetles (Coleoptera, Carabidae) were collected using pitfall traps from four urban, four suburban and four rural sites in Hiroshima City, Japan, during the 2001 summer season. In agreement with expectation, carabid abundance and species richness decreased significantly from rural to urban sites. Furthermore, no large, and only few individuals of medium-sized specialist species were collected from the urban environment, while many specimens of medium-sized and some large-sized specialist species were collected from the suburban and rural sites. Hiroshima city was characterised by medium-sized generalist carabids, while the suburbs and the rural environments were characterised by small-sized generalist beetles. These results did not apply at the species level. To summarise, we found a significant effect of urbanisation on the composition of carabid beetle assemblages in Hiroshima City. These changes were similar to those found in previous studies performed in Sofia (Bulgaria), Edmonton (Canada) and Helsinki (Finland). Thus, it appears that urbanisation has some similar and predictable effects on carabid assemblages in various parts of the world.     

A standardized sampling method to estimate mosquito richness and abundance for research and public health surveillance programmes

Programmes involving mosquito research and surveillance are normally focused on the study of aquatic larval stages, but sampling methods are varied and not systematized, which hinders the comparative analysis of ecological data. A standardized method for assessing the richness and abundance of mosquito larval populations of value for the analysis of mosquito diversity is presented. Based on the study of all the aquatic sites in a one hectare sample area with a proportional number of dips according to the size of the aquatic habitat, comparative data can be obtained on species richness and relative abundance of species found between pairs of sites or in the same area at different times. This technique provides information on the total mosquito fauna at each site, helps recognize species of medical importance and estimates the abundance of each species; parameters that are not estimated by the current entomological indexes used in surveillance programmes. The quality of the inventory is obtained by estimation of the efficiency effort. Procedures for calculating alpha, beta and gamma diversity are presented. The technique was validated in a natural and an urban zone at La Mancha, Veracruz, Mexico, over two years of sampling made during different climatic seasons.     

Wild bees respond complementarily to ‘high-quality’ perennial and annual habitats of organic farms in a complex landscape

Agricultural intensification leads to large-scale loss of habitats offering food and nesting sites for bees. This has resulted in a severe decline of wild bee diversity and abundance during the past decades. There is an urgent need for cost-effective conservation measures to mitigate this decline. We analysed the impact of five different high-quality habitats on species richness and abundance of wild bees in a complex landscape of north-western Switzerland at six sites. The five habitat types included 45 plots situated on eight organic farms and were composed of 16 low-input meadows, six low-input pastures, seven herbaceous strips adjacent to hedges, five sown flower strips and eleven organic cereal fields. All of them are financially subsidised by the Swiss agri-environmental scheme. Wild bees were sampled between the end of April and end of August 2014 by using trio-pan traps and complementary sweep netting on these five habitat types. On 45 plots we recorded 3973 bee specimens, belonging to 91 species, 16 of which are red listed, revealing a high bee species richness in the study area. Wild bee species richness and abundance were best explained by habitat type, number of flowering plants and site. A strong relationship of increasing number of flowering plants and bee species richness and abundance was found. Grassland habitats, especially low-input meadows, harboured the highest species richness and abundances. Organic cereal fields showed a potential to conserve bee species relevant to nature conservation (harbouring exclusively two red list species and four rare species). Ordination analysis of the bee communities showed a relative dissimilarity between the habitat types and indicates their complementary effects to benefit the diversity of wild bees. Our results demonstrate that a matrix of low-input habitats are needed to sustain rich assemblages of wild bees in agroecosystems.     

The worldwide impact of urbanisation on avian functional diversity

Urbanisation is driving rapid declines in species richness and abundance worldwide, but the general implications for ecosystem function and services remain poorly understood. Here, we integrate global data on bird communities with comprehensive information on traits associated with ecological processes to show that assemblages in highly urbanised environments have substantially different functional composition and 20% less functional diversity on average than surrounding natural habitats. These changes occur without significant decreases in functional dissimilarity between species; instead, they are caused by a decrease in species richness and abundance evenness, leading to declines in functional redundancy. The reconfiguration and decline of native functional diversity in cities are not compensated by the presence of exotic species but are less severe under moderate levels of urbanisation. Thus, urbanisation has substantial negative impacts on functional diversity, potentially resulting in impaired provision of ecosystem services, but these impacts can be reduced by less intensive urbanisation practices.     

Recovery of Native Plant Community Characteristics on a Chronosequence of Restored Prairies Seeded into Pastures in West‐Central Iowa

Restored grasslands comprise an ever‐increasing proportion of grasslands in North America and elsewhere. However, floristic studies of restored grasslands indicate that our ability to restore plant communities is limited. Our goal was to assess the effectiveness of restoration seeding for recovery of key plant community components on former exotic, cool‐season pastures using a chronosequence of six restoration sites and three nearby remnant tallgrass prairie sites in West‐Central Iowa. We assessed trends in Simpson's diversity and evenness, richness and abundance of selected native and exotic plant guilds, and mean coefficient of conservatism (mean C). Simpson's diversity and evenness and perennial invasive species abundance all declined with restoration site age. As a group, restoration sites had greater richness of native C₃ species with late phenology, but lower richness and abundance of species with early phenology relative to remnant sites. Total native richness, total native abundance (cover), mean C, and abundance of late phenology C₃ plants were similar between restoration and remnant sites. Observed declines in diversity and evenness with restoration age reflect increases in C₄ grass abundance rather than absolute decreases in the abundance of perennial C₃ species. In contrast to other studies, restoration seeding appears to have led to successful establishment of tallgrass prairie species that were likely to be included in seeding mixtures. While several floristic measures indicate convergence of restoration and remnant sites, biodiversity may be further enhanced by including early phenology species in seeding mixes in proportion to their abundance on remnant prairies.     

Macro‐ and microenvironmental factors affecting tyre‐breeding flies (Insecta: Diptera) in urbanised areas

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Evaluating the effects of urbanisation on salamander abundances using a before‐after control‐impact design

1. Urbanisation represents a significant threat to semi‐aquatic amphibian populations, especially stream‐dwelling salamanders. Although studies of urbanisation effects on amphibians have been conducted, there is an urgent need to follow populations over longer time periods, account for imperfect detection and determine the response time to urbanisation. Consequently, we used a before‐after control‐impact (BACI) study design to estimate changes in abundances of larval and adult salamanders in streams affected by urbanisation. 2. From 2005 to 2009, we used standard sampling techniques to obtain a count of salamanders in 13 first‐order streams that underwent urbanisation of their catchments after the first year of sampling. Simultaneously, we counted salamanders in 17 streams that experienced no disturbance within stream catchments. Additionally, we measured environmental variables at each stream. 3. We used Royle’s binomial mixture model to estimate annual mean abundances and individual detection probabilities, and Bayesian inference was used to estimate population parameters for each stage and species. 4. Although mean abundance estimates varied among years in control and urbanised streams, we found that urbanisation had a negative effect on larval and adult salamander abundances. Larval salamander abundances at sites 1 year after urbanisation were significantly lower than abundances from control sites. Abundances of adult two‐lined salamanders (Eurycea cirrigera) at urbanised sites were lower than abundances at control sites 2 years post‐urbanisation, and adult dusky salamander (Desmognathus fuscus) abundances at urbanised sites were lower than abundances at control sites 3 years post‐urbanisation. Maximum conductivity, sedimentation level and maximum stream channel width differed between urban and non‐urban streams. 5. Our results suggest that stream‐dwelling salamanders exhibit little resistance to urbanisation. Our study also highlights the use of the BACI design to study how urbanisation affects populations in semi‐aquatic habitats. We emphasise that inferences regarding urbanisation effects on population response may be compromised unless urban populations are compared to populations in control sites, especially for species in which populations fluctuate.     

Differential Responses to Woodland Character and Landscape Context by Cryptic Bats in Urban Environments

Urbanisation is one of the most dramatic forms of land use change which relatively few species can adapt to. Determining how and why species respond differently to urban habitats is important in predicting future biodiversity loss as urban areas rapidly expand. Understanding how morphological or behavioural traits can influence species adaptability to the built environment may enable us to improve the effectiveness of conservation efforts. Although many bat species are able to exploit human resources, bat species richness generally declines with increasing urbanisation and there is considerable variation in the responses of different bat species to urbanisation. Here, we use acoustic recordings from two cryptic, and largely sympatric European bat species to assess differential responses in their use of fragmented urban woodland and the surrounding urban matrix. There was a high probability of P. pygmaeus activity relative to P. pipistrellus in woodlands with low clutter and understory cover which were surrounded by low levels of built environment. Additionally, the probability of recording P. pygmaeus relative to P. pipistrellus was considerably higher in urban woodland interior or edge habitat in contrast to urban grey or non-wooded green space. These results show differential habitat use occurring between two morphologically similar species; whilst the underlying mechanism for this partitioning is unknown it may be driven by competition avoidance over foraging resources. Their differing response to urbanisation indicates the difficulties involved when attempting to assess how adaptable a species is to urbanisation for conservation purposes.     

Surrounding land use significantly influences adult mosquito abundance and species richness in urban mangroves

Mangroves harbor mosquitoes capable of transmitting human pathogens; consequently, urban mangrove management must strike a balance between conservation and minimizing public health risks. Land use may play a key role in shaping the mosquito community within urban mangroves through either species spillover or altering the abundance of mosquitoes associated with the mangrove. In this study, we explore the impact of land use within 500 m of urban mangroves on the abundance and diversity of adult mosquito populations. Carbon dioxide baited traps were used to sample host-seeking female mosquitoes around nine mangrove forest sites along the Parramatta River, Sydney, Australia. Specimens were identified to species and for each site, mosquito species abundance, species richness and diversity were calculated and were analyzed in linear mixed effects models. We found that the percentage of residential land and bushland in the surrounding area had a negative effect on mosquito abundance and species richness. Conversely, the amount of mangrove had a significant positive effect on mosquito abundance, and the amount of industrial land had a significant positive effect on species richness. These results demonstrate the need for site-specific investigations of mosquito communities associated with specific habitat types and the importance of considering surrounding land use in moderating local mosquito communities. A greater understanding of local land use and its influence on mosquito habitats could add substantially to the predictive power of disease risk models and assist local authorities develop policies for urban development and wetland rehabilitation.     

Effects of land use on water quality and aquatic biota of three North Carolina Piedmont streams

Three streams in the Piedmont ecoregion of North Carolina were studied to evaluate the effect of land use (forested, agricultural, urban) on water quality and aquatic biota. In comparison with the forested stream, there were few changes in water quality at the agricultural and urban streams. Suspended-sediment yield was greatest for the urban catchment and least at the forested catchment. Suspended-sediment concentrations during storm events followed this same pattern, but at low-moderate flows suspended-sediment concentrations were greatest at the agricultural site. Most nutrient concentrations were highest at the agricultural site, and the amount of available dissolved nitrogen was elevated at both the urban and agricultural sites. High concentrations of metals (totals) in the water column were sometimes observed at all sites, but maximum average concentrations were recorded at the urban site (especially Cr, Cu, and Pb). Maximum sediment metal concentrations, however, were not found at the urban site, but were usually recorded at the forested site. Only minor differences were noted between fish communities of the forested and agricultural sites, although both abundance and average size of some species increased at the agricultural site. The fish community at the urban site was characterized by low species richness, low biomass, and the absence of intolerant species.Invertebrate taxa richness, a biotic index, and the number of unique invertebrate species (found at only one site) indicated moderate stress (Fair water quality) at the agricultural site and severe stress (Poor water quality) at the urban site. At the agricultural site, declines in taxa richness within intolerant groups were partially offset by increases within tolerant groups. The agricultural stream had the highest abundance values, indicating enrichment. The urban site, however, was characterized by low species richness for most groups and very low abundance values. Analysis of seasonal patterns suggested detritus was the most important food source for invertebrates in the forested stream, while periphyton was of greater importance in the agricultural stream. Dominant macroinvertebrate groups shifted from Ephemeroptera at the forested site, to Chironomidae at the agricultural site, and Oligochaeta at the urban site. There was little between-site overlap in dominant species (8–7%), indicating that land use strongly influenced the invertebrate community. Chemical and physical parameters measured at the three sites did not seem sufficient to account for all of the observed differences in the invertebrate communities, suggesting some unmeasured toxicity. Biological measurements, especially macroinvertebrates community structure, consistently indicated strong between-site differences in water and habitat quality.     

Variability of zooplankton community along a section of the Upper Victoria Nile, Uganda

Zooplankton community along a stretch of Upper Victoria Nile was investigated at selected sites between Kalange and Namasagali during April, August and October 2000 as part of a wider ecological study to generate biological baseline data prior to construction of a hydropower plant at Dumbbell Island. The study provided an opportunity to investigate a riverine zooplankton community for comparison with the more studied lake communities. Field sampling was made with a plankton net of 25 cm mouth opening and 60 μm nitex mesh; fitted with sandbags for ease of operation in water currents. Zooplankton subsamples were examined under an inverted microscope at ×100 magnification. The 27 species encountered belong to three broad taxonomic groups: Copepoda, Cladocera and Rotifera. Rotifers had the highest number of species (sixteen) followed by copepods (six). Species richness and total numerical abundance were high at the two upstream sites and decreased significantly downstream. High zooplankton densities at upstream sites during April plummeted to much lower levels in August and October. By comparison, species richness and numerical abundance were much lower than those of Lake Victoria; the ultimate source of the Upper Victoria Nile water. This may be due to differences between lotic and lentic habitats as both physical and biological processes are known to be limited under flowing water conditions. The high species richness and numerical abundance at the two upstream sites may be due to positioning of sampling points downstream of islands and/or rock outcrops for ease of net sampling as well as a richer food environment observed in a parallel study of algal biomass. The type and level of impacts of the proposed hydropower station on biological communities will be determined by site location: either upstream or downstream of the plant. Monitoring surveys of both environment and biological parameters during and after construction of the power plant will be necessary to keep track of ecosystem changes and their implications.     

Influences of low-head dams on the fish assemblages in the headwater streams of the Qingyi watershed, China

The influences of low-head dams on the fish assemblages were examined in this study, using fish data collected in six treatment and five reference sites at three low-head dams in the headwater streams of the Qingyi watershed, China. Comparing with those in the reference sites, local habitat variables were significantly altered by low-head dams in the treatment sites, involving wider channel (only in the impoundment area), deeper water and slower flow. Fish species richness varied significantly across seasons, not across site categories, suggesting that these low-head dams did not alter species richness. However, significant decreases in fish abundance and density were observed in the impoundment areas immediately upstream of dams, but not in the plunge areas downstream. Fish assemblage structures kept relative stability across seasons, and their significant difference between-site was only observed between the impoundment areas and the sites far from dams upstream. This variation in assemblage structures was due to the differing relative abundance of some co-occurring species; more lentic but less lotic fish was observed in the impoundment areas. The spatial and temporal patterns of fish assemblages were correlated with local habitat in this study area. Wetted width had negative correlation with fish species richness, abundance and density, respectively. Water temperature also positively affected species richness. In addition, wetted width, water depth, current velocity and substrate were the important habitat variables influencing assemblage structures. Our results suggested that, by modifying local habitat characteristics, low-head dams altered fish abundance and density in the impoundment areas immediately upstream of dam, not in the plunge areas immediately downstream, and thereby influenced fish assemblage structures in these stream segments.     

Effects of stream restoration and wastewater treatment plant effluent on fish communities in urban streams

1. Fish community characteristics, resource availability and resource use were assessed in three headwater urban streams in Piedmont North Carolina, U.S.A. Three site types were examined on each stream; two urban (restored and unrestored) and a forested site downstream of urbanisation, which was impacted by effluent from a wastewater treatment plant (WWTP). Stream basal resources, aquatic macroinvertebrates, terrestrial macroinvertebrates and fish were collected at each site. 2. The WWTPs affected isotope signatures in the biota. Basal resource, aquatic macroinvertebrate and fish δ¹⁵N showed significant enrichments in the downstream sites, although δ¹³C signatures were not greatly influenced by the WWTP. Fish were clearly deriving a significant part of their nutrition from sewage effluent‐derived sources. There was a trend towards lower richness and abundance of fish at sewage‐influenced sites compared with urban restored sites, although the difference was not significant. 3. Restored stream sites had significantly higher fish richness and a trend towards greater abundance compared with unrestored sites. Although significant differences did not exist between urban restored and unrestored areas for aquatic and terrestrial macroinvertebrate abundances and biotic indices of stream health, there appeared to be a trend towards improvements in restored sites for these parameters. Additional surveys of these sites on a regular basis, along with maintenance of restored features are vital to understanding and maximising restoration effectiveness. 4. A pattern of enriched δ¹³C in fish in restored and unrestored streams in conjunction with enriched δ¹³C of terrestrial invertebrates at these sites suggests that these terrestrial subsidies are important to the fish, a conclusion also supported by isotope cross plots. Furthermore, enriched δ¹³C observed for terrestrial invertebrates is consistent with some utilisation of the invasive C4 plants that occur in the urban riparian areas.     

Effects of Long Piers on Birds in Tidal Wetlands

ABSTRACT As human development continues in coastal areas, shoreline properties adjacent to expansive tidal marsh habitat are increasingly used for access to coastal waterways via long piers (>30 m) over marsh habitat. These tidal wetlands provide breeding and foraging habitat for many marsh birds, which may be affected by the human disturbance associated with long piers. Our objectives were to determine the effect of long piers over vegetated tidal marshes on the relative abundance and species richness of marsh birds. We completed combined passive and callback surveys in tidal marsh habitat at 22 sites with long piers and 24 sites without long piers, May-July 2005–2006 in Worcester County, Maryland, USA. Pier sites had lower relative abundance and species richness of obligate marsh birds than nonpier sites. Pier sites had a greater relative abundance of gulls, terns, herons, and egrets than nonpier sites. Pier sites had fewer species of herons and egrets than at nonpier sites. The presence of long piers had no affect on facultative marsh birds. Long pier density was negatively related to obligate marsh bird relative abundance and species richness, and facultative marsh bird species richness, whereas it was positively related to the relative abundance and species richness of gulls and terns. Herons and egrets relative abundance and species richness were not related to long pier density. Obligate marsh birds were negatively affected by long piers, whereas herons, egrets, gulls, and terns appeared to benefit from perching opportunities. Based on the negative effects of long piers on obligate marsh birds, management should focus on reducing the presence and density of long piers in tidal marshes by requiring the removal of existing long piers, or reducing or eliminating permits for construction of new long piers.