Abundance Of Epifauna Research Articles

Detrital traits affect substitutability of a range‐expanding foundation species across latitude

Climate‐driven range shifts of foundation species could alter ecosystem processes and community composition by providing different resources than resident foundation species. Along the US Atlantic coast, the northward expanding foundation species, black mangrove Avicennia germinans, is replacing the dominant salt marsh foundation species, marsh cordgrass Spartina alterniflora. These species have distinct detrital attributes that ostensibly provide different resources to epifauna. We experimentally examined how detritus of these species affects decomposition and community composition in different habitat contexts at regional and local scales. First, we manipulated detritus identity (Avicennia, Spartina) at 13 sites across a 5° latitudinal gradient spanning mangrove, mixed marsh‐mangrove and salt marsh habitats. Across latitude, we found that Avicennia detritus decomposed 2–4 times faster than Spartina detritus, suggesting that detrital turnover will increase with mangrove expansion. Epifaunal abundance and richness increased 2–7 times from south to north (mangrove to salt marsh) and were equivalent between Avicennia and Spartina detritus except for crabs, a dominant taxonomic group that preferred Spartina detritus. Second, to examine the whether changing habitat context affected regional patterns, we manipulated detritus identity and surrounding habitat type (mangrove, salt marsh) at a single mixed site, also including inert mimics to separate structural and nutritional roles of detritus. Epifaunal richness was similar between the two detrital types, but crabs were 2–7 times more abundant in Spartina detritus due to its structural attributes. Surrounding habitat type did not influence decomposition rate or community patterns, which suggests that latitudinal influences, not surrounding habitat, drove the regional community patterns in the first experiment. Overall, mangrove expansion could alter epifaunal communities due to the lower structural value and faster turnover of mangrove detritus. As species shift with changing climate, understanding foundation species substitutability is critical to predict community change, but we must account for concomitant environmental changes that also modify communities.

Using 3D photogrammetry from ROV video to quantify cold-water coral reef structural complexity and investigate its influence on biodiversity and community assemblage

Fine-scale structural complexity created by reef-building coral in shallow-water environments is influential on biodiversity, species assemblage and functional trait expression. Cold-water coral reefs are also hotspots of biodiversity, often attributed to the hard surface and structural complexity provided by the coral. However, that complexity has seldom been quantified on a centimetric scale in cold-water coral reefs, unlike their shallow-water counterparts, and has therefore never been linked in a similar way to the reef inhabitant community. Structure from motion techniques which create high-resolution 3D models of habitats from sequences of photographs is being increasingly utilised, in tandem with 3D spatial analysis to create useful 3D metrics, such as rugosity. Here, we demonstrate the use of ROV video transect data for 3D reconstructions of cold-water coral reefs at depths of nearly 1000 m in the Explorer Canyon, a tributary of Whittard Canyon, NE Atlantic. We constructed 40 3D models of approximately 25-m-length video transects using Agisoft Photoscan software, resulting in sub-centimetre resolution reconstructions. Digital elevation models were utilised to derive rugosity metrics, and orthomosaics were used for coral coverage assessment. We found rugosity values comparable to shallow-water tropical coral reef rugosity. Reef and nearby non-reef communities differed in assemblage composition, which was driven by depth and rugosity. Species richness, epifauna abundance and fish abundance increased with structural complexity, being attributed to an increase in niches, food, shelter and alteration of physical water movement. Biodiversity plateaued at higher rugosity, illustrating the establishment of a specific reef community supported by more than 30% coral cover. The proportion of dead coral to live coral had limited influence on the community structure; instead, within-reef patterns were explained by depth and rugosity, though our results were confounded to a certain extent by multi-collinearity. Fine-scale structural complexity appeared to be integral to local-scale ecological patterns in cold-water coral reef communities.

Differences in architecture between native and non-indigenous macroalgae influence associations with epifauna

Non-indigenous invaders may play ecologically similar roles to native species, and this may be reflected in the abundance, richness and composition of associated species assemblages. We investigated whether associations of epifauna with their macroalgal hosts differed between the non-indigenous Codium fragile ssp. fragile and native, congeneric C. fragile on three rocky shores in southeast Australia. Of the 38 taxa we recorded, 13 were unique to the native Codium and four to non-indigenous individuals. Holdfasts of non-indigenous Codium had double the taxon richness of epifauna compared to native holdfasts, and epifaunal abundances showed a similar but non-significant difference. Patterns of abundance and richness of epifaunal taxa on thalli of native and non-indigenous Codium varied depending on whether these measures were expressed per individual alga, thallus area or number of branches. The composition of epifaunal assemblages between native and non-indigenous Codium were significantly different, but differences among rocky shores were as great as those between macroalgal species. On all shores, two taxa, the gastropod Alaba opiniosa and gammarid amphipods, contributed most to compositional differences between native and non-indigenous Codium, and their abundances were influenced by branch number and associated epiphyte load. Host choice experiments manipulating the complexity and subspecies of Codium revealed that amphipods were more strongly influenced by branch number adjusted for epiphyte load than the identity of Codium. Our results highlight the importance of habitat features, such as structural complexity and associated epiphyte load, in determining whether native and non-indigenous species provide functionally equivalent habitats for associated assemblages.

Epifaunal community response to iceberg-mediated environmental change in McMurdo Sound, Antarctica

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 613:1-14 (2019) - DOI: https://doi.org/10.3354/meps12899 FEATURE ARTICLE Epifaunal community response to iceberg-mediated environmental change in McMurdo Sound, Antarctica Stacy Kim1,*, Kamille Hammerstrom1, Paul Dayton2 1Moss Landing Marine Labs, 8272 Moss Landing Rd., Moss Landing, CA 95039, USA 2Scripps Institution of Oceanography, UC San Diego, 9500 Gilman Drive #0227, La Jolla, CA 92093-0227, USA *Corresponding author: skim@mlml.calstate.edu ABSTRACT: High-latitude marine communities are dependent on sea ice patterns. Sea ice cover limits light, and hence primary production and food supply. Plankton, carried by currents from open water to areas under the sea ice, provides a transitory food resource that is spatially and temporally variable. We recorded epifaunal abundances at 17 sites in McMurdo Sound, Antarctica, over 12 yr, and found differences in communities based on location and time. The differences in location support patterns observed in long-term infaunal studies, which are primarily driven by currents, food availability, and larval supply. The temporal differences, highlighting 2004 and 2009 as years of change, match the altered persistence of sea ice in the region, caused by the appearance and disappearance of mega-icebergs. The temporal changes were driven by changes in abundance of species that filter feed on large particulates. The shift in current patterns that occurred due to mega-icebergs decreased the normal food supply in the region. In addition to the decrease in food availability, we suggest that the reduced light resulting from thicker-than-normal sea ice resulted in a shift to smaller phytoplankton. A change in food quality as well as quantity may have influenced the temporal change in epifaunal communities. KEY WORDS: Long-term · Decadal · Benthic · Megafauna Full text in pdf format Information about this Feature Article Supplementary material NextCite this article as: Kim S, Hammerstrom K, Dayton P (2019) Epifaunal community response to iceberg-mediated environmental change in McMurdo Sound, Antarctica. Mar Ecol Prog Ser 613:1-14. https://doi.org/10.3354/meps12899 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 613. Online publication date: March 21, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Detecting Indicator Taxa Associated with Benthic Organic Enrichment Using Different Video Camera Orientations

Sutherland, T.F.; Sterling, A.M.; Shaw, K.L.; Blasco, N.N.J., and Bradford, M.J., 2019. Detecting indicator taxa associated with benthic organic enrichment using different video camera orientations. Journal of Coastal Research, 35(2), 467–479. Coconut Creek (Florida), ISSN 0749-0208.Two video cameras mounted on a remotely operated vehicle (ROV) were used to generate paired forward-facing (FF) and downward-facing (DF) observations of benthic epifauna along 10 single transects at eight marine finfish aquaculture sites in British Columbia, Canada. The abundance of mat-forming primary indicators of organic enrichment, such as sulphide-oxidizing bacteria and opportunistic polychaete complexes (OPC), were quantified through percentage coverage estimates. Coverage estimates for sulphide-oxidizing bacteria were strongly correlated between the FF and DF orientations across all substrate types. The occurrence of OPC was limited to a single mixed-substrate site, which provided the strongest FF vs. DF relationship within this study. In contrast to sulphide-oxidizing bacteria, epifaunal abundance (count data) revealed strong relationships between camera orientations for fine sediments and mixed sediments and a weaker relationship observed for vertical rock wall environments. Similar observations occurred for estimates of both sessile (dominated by plumose anemones) and motile taxa guilds comprising the total epifaunal community. Weaker relationships associated with the rock wall substrate are likely due to alternating blackout periods experienced by each camera orientation as the ROV passes vertical or ledge habitat zones. Overall, a combination of FF and DF video orientations may provide more robust abundance estimates for settings that are characterized by various substrate grades and structural and/or mat-forming taxa.

Internal wave turbulence at a biologically rich Mid-Atlantic seamount.

The turbulence regime near the crest of a biologically rich seamount of the Mid-Atlantic Ridge southwest of the Azores was registered in high spatial and temporal resolution. Internal tides and their higher harmonics dominate the internal wave motions, producing considerable shear-induced turbulent mixing in layers of 10–50 m thickness. This interior mixing of about 100 times open-ocean interior values is observed both at a high-resolution temperature sensor mooring-site at the crest, 770 m water depth being nearly 400 m below the top of the seamount, and a CTD-yoyo site at the slope off the crest 400 m horizontally away, 880 m water depth. Only at the mooring site, additionally two times higher turbulence is observed near the bottom, associated with highly non-linear wave breaking. The highest abundance of epifauna, notably sponges, are observed just below the crest and 100 m down the eastern slope (700–800 m) in a cross-ridge video-camera transect. This sponge belt is located in a water layer of depressed oxygen levels (saturation 63±2%) with a local minimum centered around 700 m. Turbulent mixing supplies oxygen to this region from above and below and is expected to mix nutrients away from this biodegraded layer towards the depth of highest abundance of macrofauna.

Positive and negative interactions control a facilitation cascade

AbstractFacilitation cascades, which enhance the diversity of ecological communities in many ecosystems, have been viewed as the net outcome of positive species’ interactions. The strength and direction of these interactions, and thus the realized biodiversity, however, are likely to vary with the density and traits of the habitat‐formers and via negative interactions among interacting species. To test this, we manipulated the density and status (alive vs. dead) of a secondary habitat‐former, the razor clam Pinna sp., and measured responses by the primary habitat‐former, the seagrass Zostera muelleri, associated epifauna and infauna, and fish foraging behavior. At the plot level, for both live and dead clams, the total abundance of epifauna increased with clam density. However, for individual clams, the density of epifauna/cm2 decreased with increasing clam density. Video image analysis showed higher fish predation of epifauna on dead compared to live clams at high but not low densities and path analysis indicated that these strong negative trophic interactions increased with dead clam density via both direct and indirect pathways. By contrast, an increasing density of live but not dead clams was negatively correlated with seagrass faunal densities. However, seagrass growth and standing biomass were unaffected by clam density or status. Our study illustrates that the realized facilitation cascade is a function of nested negative and positive interactions which change as a function of the density of clams and whether they were dead or alive, and therefore do not represent a collection of hierarchical positive interactions.

The invasive kelp Undaria pinnatifida hosts an epifaunal assemblage similar to native seaweeds with comparable morphologies

Invasive seaweeds have the potential to disrupt ecosystem functioning if they are unsuitable hosts for the small mobile invertebrates (epifauna) that are an important trophic link between benthic primary producers and higher trophic levels. The Asian kelp Undaria pinnatifida has successfully invaded many coastal regions worldwide. We compared the epifaunal assemblage on U. pinnatifida with epifauna of 7 co-occurring, canopy-forming native brown seaweed species in southern New Zealand to help understand the effect of the invasive species on shallow subtidal ecosystems. The density, diversity and composition of epifauna across the 8 seaweeds were much more strongly related to host morphology than to the geographic origin of the host. U. pinnatifida and several native seaweeds with similarly simple morphologies supported relatively depauperate epifaunal assemblages dominated by copepods. More structurally complex native seaweeds supported more abundant and diverse epifaunal assemblages containing lower proportions of copepods and higher proportions of amphipods and other epifaunal groups. Our results indicate that abundances of epifauna at the ecosystem level will be reduced if U. pinnatifida displaces more structurally complex native seaweed species that host more diverse and dense epifaunal assemblages. The findings suggest that morphological complexity may be key to predicting the impacts of invasive seaweeds on epifaunal assemblages, and potentially on food webs, in other geographic regions.

Epifaunal community composition in five macroalgal species – What are the consequences if some algal species are lost?

Anthropogenic disturbances such as eutrophication and climate change are affecting the distribution and coverage of macroalgae in coastal areas worldwide. How these changes will affect the littoral food webs is challenging to predict as we still lack basic knowledge of epifaunal communities in different macroalgal species. The aim of this study was therefore to compare the epifauna in five common macroalgal species in the northern Baltic Sea. Samples of macroalgae and the associated epifauna were collected in mesh bags at 2 m depth in July–August 2014. The epifaunal abundance data were analyzed with univariate and multivariate methods. The results revealed significant differences in the epifaunal composition among the studied macroalgal species. Ceramium tenuicorne hosted the significantly highest and Fucus vesiculosus the lowest abundance of epifauna per algal dry weight. When comparing the relative epifaunal abundances in percentage, we found that different epifaunal taxa representing different functional groups dominated Pylaiella littoralis (Chironomidae, deposit feeder), Cladophora rupestris (Gammarus spp., herbivorous/omnivorous) and Furcellaria lumbricalis (Mytilus trossulus, suspension feeder). However, most of the epifaunal taxa were found in all algal species studied. We conclude that the loss or decline of specific macroalgal species will affect the ecosystem functions and energy flows to the higher trophic levels, but that none of the studied algal species seems to be crucial for the existence of single taxa or functional group of epifauna.

Epibenthic diversity and productivity on a heavily trawled Barents Sea bank (Tromsøflaket)

Shallow Arctic banks have been observed to harbour rich communities of epifaunal organisms, but have not been well-studied with respect to composition or function due to sampling challenges. In order to determine how these banks function in the Barents Sea ecosystem, we used a combination of video and trawl/dredge sampling at several locations on a heavily trawled bank, Tromsøflaket – located at the southwestern entrance to the Barents Sea. We describe components of the benthic community, and calculate secondary production of dominant epifaunal organisms. Forty-six epibenthic taxa were identified, and sponges were a significant part of the surveyed benthic communities. There were differences in diversity and production among areas, mainly related to the intensity of trawling activities. Gamma was the most diverse and productive area, with highest species abundance and biomass. Trawled areas had considerably lower species numbers, and significant differences in epifaunal abundance and biomass were found between all trawled and untrawled areas. Trawling seems to have an impact on the sponge communities: mean individual poriferan biomass was higher in untrawled areas, and, although poriferans were observed in areas subjected to more intensive trawling, they were at least five times less frequent than in untrawled areas.

Nonnative Species in British Columbia Eelgrass Beds Spread via Shellfish Aquaculture and Stay for the Mild Climate

Nonnative species cause economic and ecological impacts in habitats they invade, but there is little information on how they spread and become abundant. This is especially true for nonnative species in native Zostera marina eelgrass beds in coastal British Columbia, Canada, which play a vital role in estuarine ecosystems. We tested how nonnative species richness and abundance were related to both arrival vectors and environmental factors in northeast Pacific eelgrass. Using correlation tests and generalized linear models, we examined how nonnative macroinvertebrates (benthic, epifaunal, and large mobile) and some algae species were related to arrival vectors (shipping and aquaculture) and environmental factors (climate variables, human population density, and native richness and abundance). We found 12 nonnative species, 50 % with known negative impacts within eelgrass habitats. For benthic organisms, both nonnative richness and abundance were strongly correlated with shellfish aquaculture activities, and not with shipping activity. For epifaunal nonnative richness and abundance, neither vector was significantly correlated. Climate (temperature and salinity) helped explain nonnative richness but not abundance; there was no relationship of nonnative richness or abundance to native species richness and abundance or population density. Results suggest that aquaculture activities are responsible for many primary introductions of benthic nonnative species, and that temperature and salinity tolerances are responsible for post-introduction invasion success. While aquaculture and shipping vectors are becoming increasingly regulated to prevent further international spread of nonnative species, it will be important when managing nonnatives to consider secondary spread from intraregional transport through local shellfish aquaculture and shipping.

Recruitment pattern of benthic fauna on artificial substrates in brackish low-diversity system (the Baltic Sea)

Recruitment pattern of benthic fauna in temperate marine ecosystems is still not well recognized, particularly in inland coastal seas with distinct environmental and ecological conditions. This study investigates the effect of natural surrounding community structure, environmental variables and substrate orientation on short-term recruitment of motile and sessile epibenthos in the southern Baltic Sea. Recruitment on topsurface and undersurface of Perspex panels deployed on the seafloor in a horizontal position was monitored monthly from March 2008 to March 2010 in two coastal habitats (sandy and gravelly) in the Gulf of Gdansk. Recruitment of epibenthic invertebrates took place primarily over a growing season (March–October) indicating that reproduction and settlement are driven by water temperature and gross primary production. Communities of recruits showed relatively homogenous spatial taxonomic composition but total epifaunal abundance varied between bottom types. Planktonic larvae supply and species-specific recruitment behaviour account primarily for settlement success, particularly on panel topsurface which hosted more diverse and more abundant recruits than panel undersurface. Relative to vertical substrates, horizontal panels had less numerous barnacle recruits probably due to inhibitory effect of sediment deposition and organic biofilm.

Habitat restoration: Early signs and extent of faunal recovery relative to seagrass recovery

The overall intent of restoration is often not only to restore the habitat per se, but to restore the ecosystem services it supplies, and particularly to encourage the return of fauna. Seagrass meadows act as habitat for some of the most diverse and abundant animal life, and as the global loss of seagrass continues, managers have sought to restore lost meadows. We tested how quickly the epifaunal richness, abundances and community composition of experimental restoration plots recovered to that in an adjacent natural seagrass meadow relative to the recovery of seagrass per se. Seagrass structure in the restoration plots took three years to become similar to a nearby natural meadow. The recovery of epifaunal richness and total abundance, however, occurred within one year. These results suggest that although recovering habitats may not be structurally similar to undisturbed habitats, they can support similar richness and abundances of epifauna, and thus have greater economic and social value than otherwise might have been expected. Nevertheless, whilst epifaunal richness and total abundance recovered prior to the recovery of seagrass structure, full recovery of seagrass was required before the composition and relative abundances of the epifaunal community matched that of the natural seagrass meadow.

Fish, Macroinvertebrate and Epifaunal Communities in Shallow Coastal Lagoons with Varying Seagrass Cover of the Northern Gulf of Mexico

Coastal lagoons are ubiquitous along coastlines worldwide. Here, we compare the abundance of epifauna, seagrass-associated macroinvertebrates, and small fish across a gradient of seagrass cover in shallow coastal lagoons of the northern Gulf of Mexico. Two of the lagoons had little or no seagrass cover (0–18.8 %), and four had high cover (83.8–97.5 %). All of the lagoons were partially covered with fringing marsh. We hypothesized that, due to habitat redundancy between seagrass beds and fringing marshes, seagrass-associated fish and macroinvertebrates would not be largely reduced despite the large differences in seagrass cover among the lagoons. Our results support this hypothesis. For most sampling dates, we did not find significant differences in fish and macroinvertebrate abundance among the lagoons and, when we did, several highly vegetated lagoons did not have larger abundances than sparsely vegetated lagoons. The extreme shallowness of the lagoons studied (<1 m) may also provide further protection from large predatory fishes in the absence of seagrasses. Our results also suggest that marsh detritus, by providing habitat for epifauna and helping maintain prey availability, may further temper reductions in seagrass-associated fishes and macroinvertebrates following seagrass decline. The results highlight the importance of marsh-bordered, shallow lagoons as habitat for small fish and macroinvertebrates regardless of seagrass cover. This study contributes to the characterization of habitat redundancy in coastal ecosystems and pinpoints the importance of considering all habitats in concert for the proper understanding and management of coastal ecosystems.

Overgrowth of eelgrass by the invasive colonial tunicate Didemnum vexillum: Consequences for tunicate and eelgrass growth and epifauna abundance

The invasive tunicate Didemnum vexillum has become widely distributed in estuaries in western North America over the past decade. It has recently invaded eelgrass meadows in a central California estuary, growing directly on shoots and rhizomes. This invasion is of concern due to the important role of eelgrass as a foundation species in coastal communities and the known detrimental effects of this tunicate on sessile organisms in other habitats. The effects of tunicate overgrowth on eelgrass growth and morphology were studied using surveys, field experiments, and outdoor mesocosm experiments. In field and mesocosm experiments, there were decreases in eelgrass aboveground growth relative to unfouled shoots. Comparison of D. vexillum growth rates on eelgrass vs. hard substrate in mesocosms showed that growth was higher on hard substrate. The effects of D. vexillum overgrowth on the eelgrass epifaunal community were also characterized; overall invertebrate densities, and specifically tanaid and polychaete densities, were higher on shoots fouled with D. vexillum. Overall, the mean cover of D. vexillum on eelgrass shoots in the field was approximately 15–20% of shoot length. As the eelgrass in the mesocosms had less D. vexillum coverage than in the field, these results are conservative and suggest that relatively low D. vexillum coverage of individual eelgrass shoots may result in modest impacts on eelgrass.

Beyond the border: Effects of an expanding algal habitat on the fauna of neighbouring habitats

The impacts of novel habitat-forming organisms on associated fauna have been difficult to predict, and may affect the fauna of neighbouring habitats due to changes in the spatial configuration of habitat patches of differing quality. Here, we test whether the localised expansion of a native habitat-forming macroalga, Caulerpa filiformis, on subtidal reefs can affect the abundance of fauna associated with a neighbouring macroalgal habitat. C. filiformis was a functionally distinct habitat for fauna, and the total abundance of epifauna associated with the resident alga, Sargassum linearifolium, was reduced at some sites when in close proximity to or surrounded by C. filiformis. Experimental manipulation of habitat configuration demonstrated that the low abundance of gastropods on S. linearifolium when surrounded by C. filiformis was likely explained by C. filiformis acting as a physical dispersal barrier for mobile fauna. Changes to the spatial configuration of novel and resident habitats can thus affect the abundance of fauna in addition to the direct replacement of habitats by species undergoing range expansions or increasing in abundance.

The role of annual macroalgal morphology in driving its epifaunal assemblages

Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-vegetated habitats. In this study, intertidal annual macroalgae were used as model organisms to test the role of macroalgal morphology in driving the structure of their associated epifaunal assemblages. For this aim, 6 macroalgal species, apparently different in morphology, were sampled from two intertidal rocky shores to examine the effects of habitat morphology on the number of individuals, taxa richness and the structure of its associated epifaunal assemblages by means of univariate and multivariate techniques. To provide a complete overview of macroalgal morphology, biomass was used as a proxy of habitat quantity and fractal measures as proxies of habitat complexity. Results showed that almost all the studied pairs of macroalgae showed significant differences at least for one of the morphological measures used. Moreover, epifaunal assemblages showed significant differences between macroalgae mainly due to the different identities and relative abundance of epifaunal species. However, differences in the abundance and structure of assemblages were shore dependent, possibly due to the surrounding landscape heterogeneity. Finally, the quantity of habitat was a better predictor variable than fractal measures but fractal area was also important particularly for the abundance of the total assemblage and crustaceans.

The ecosystem service value of living versus dead biogenic reef

Mixed maerl beds (corralline red algae) comprise dead thalli with varying amounts of live maerl fragments, but previously it was not known whether the presence of the live maerl increases the ecosystem service ‘habitat provision’ of the dead maerl for the associated epibenthos. A ‘flying array’ towed sled with high definition video was used to film transects of the epibenthos in dead maerl and mixed maerl beds in two locations to the north and south of the English Channel (Falmouth and Jersey). Mixed maerl beds supported greater number of taxa and abundance than dead beds in Falmouth, while in Jersey, mixed and dead beds supported similar number of taxa and dead beds had a greater abundance of epifauna. Scallops tended to be more abundant on mixed beds than dead beds. Tube worms were more abundant on mixed beds in Falmouth and dead beds in Jersey. An increasing percentage occurrence of live maerl thalli correlated with increasing number of taxa in Falmouth but not Jersey. It was concluded that while live thalli can increase the functional role of dead maerl beds for the epibenthos, this is dependent on location and response variable. As a result of this work, maerl habitat in SE Jersey has been protected from towed demersal fishing gear.

Bimini Islands: a characterization of the two major nursery areas; status and perspectives.

Bimini Islands (Bahamas, 25°44′ N 79°16′ W) are characterized by a unique tropical marine environment which provides critical nursery habitats and food resources for many important species of ecological and economical value. Two areas are particularly important in the function and dynamics of the local marine environment: North Sound and South Bimini. Since 1998 the northern part of the island has been subject to an intense urbanization process that involves the construction of an extensive touristic complex. Over the years this activity has radically modified a substantial portion of the land, and part of the underwater environment as well, threatening the fragile balance of the North Sound nursery ground. Effects on marine habitats and on local species have been reported, and although some measures to limit the damage have already been taken, the local ecosystem could ultimately suffer from continuation of the construction work on the area. In 2010, we performed surveys of both main nursery grounds to assess the current ecological status and the main differences between the two areas, investigating macrobenthic epifauna abundance, seagrass density and abiotic parameters. The results of this study indicate that the ecosystem still appears in reasonably healthy condition, although showing some concerning trends. These data provide baseline conditions to assess further changes, and possibly to support the development of plans for the conservation of the North Sound and South Bimini coastal ecosystems.

Invasive cordgrass facilitates epifaunal communities in a Chinese marsh

Structural aspects of the environment frequently influence the taxonomic and functional diversity of associated ecological communities. Spartina alterniflora and Phragmites australis both are structure-forming species in salt marshes but reciprocal invaders. Epifaunal communities on invasive Phragmites on the east coast of North America are reduced relative to native Spartina. But, the impacts of invasive Spartina on epiphytic communities in Phragmites dominated marshes in the Western Pacific are unknown. We examined epifauna on live and dead stems of invasive S. alterniflora and native P. australis in the Yangtze River estuary in China. Epiphytic invertebrate abundance on S. alterniflora was ~5× greater than on P. australis, suggesting that S. alterniflora supports more abundant epiphytic communities than P. australis, irrespective of region. For both live and dead stems, most epifaunal groups, including Namatoda, Copepoda, Halacarida and Oligochaeta, were more abundant on S. alterniflora than P. australis. Enhanced epifaunal abundance could benefit the nursery function of marshes by increasing secondary production. Dead S. alterniflora were the best habitat for nematodes, especially bacterivores and fungivores. This suggests that differences in litter quality may be important in these nematode communities and that more active biological processes may occur on Spartina influencing nutrient cycling rates.