Epifaunal Assemblages Research Articles

Evaluating fish foraging behaviour on non-indigenous Asparagopsis taxiformis using a remote video foraging system

The proliferation of pest and invasive marine macroalgae threatens coastal ecosystems, with biotic interactions, including direct effects such as grazing and indirect effects such as the trophic cascades, where one species indirectly affects another through its interactions with a third species, play a critical role in determining the resistance of local communities to these invasions. This study examines the foraging behaviour and preference of native fish communities toward native (Halopteris scoparia, Sargassum vulgare) and non-indigenous (Asparagopsis taxiformis) macroalgae using the Remote Video Foraging System (RVFS). Fifty-four weedpops were deployed across three locations to present these macroalgae, while associated epifaunal assemblages were also collected. Video analysis revealed that four common fish species displayed preference towards native macroalgae, possibly due to by the presence of zoobenthos rather than herbivory. This observation suggests that these fish species identified the macroalgae as a habitat that harboured their preferred food items. In contrast, A. taxiformis was consistently avoided, suggesting limited integration into the local food web. Site-specific variations in fish-macroalgae interactions and epifaunal diversity highlighted the complexity of these dynamics. This study contributes to understanding of the ecological implications of invasive macroalgae and supports the use of RVFS as a tool for assessing local biotic resistance against non-indigenous species in coastal ecosystems globally.

Prior stress by marine heatwaves and micro-habitat fragmentation drive the colonisation of epifaunal assemblages in marine forests

Macroalgae species of the genus Cystoseira s.l. (Fucales, Phaeophyceae) and genera Cystoseira, Ericaria, and Gongolaria are habitat-forming species from temperate areas characterised by their high productivity and associated biodiversity. These key species are declining worldwide due to multiple anthropogenic and biotic pressures, such as habitat loss or climate change-related effects. These impacts are leading to local/regional extinctions of marine forests and increasing their fragmentation and isolation. Discrete extreme temperature events in the ocean, known as marine heatwaves (MHWs), are emerging as threats to marine systems in many areas of the planet due to climate change. We analysed 74 yr of daily sea surface temperature data on the occurrence of MHWs in the Cantabrian Sea (northern Iberian Peninsula), finding a clear increase in their frequency, duration and intensity in the last 20 yr. We also performed a 10 d mesocosm experiment to assess how MHWs affect fragmented and non-fragmented patches of Ericaria selaginoides. After this experiment, the experimental patches were deployed in a tidal rock pool for 10 d to detect effects on composition and structure of associated epifaunal assemblages. Mesocosm experiment results showed how the biomass, productivity and oxygen consumption of E. selaginoides significantly decreased as MHW intensity increased. Field deployment revealed that abundance, composition and structure of the epifaunal assemblages were significantly affected by the interaction of prior stress by MHWs and patch fragmentation. Overall, our results showed how a canopy-forming macroalga is affected by extreme temperature events and, consequently, having effects on the colonisation of epifauna according to the level of microhabitat fragmentation with potential implications for the conservation of these endangered systems.

Colonization in Artificial Seaweed Substrates: Two Locations, One Year

Artificial substrates have been implemented to overcome the problems associated with quantitative sampling of marine epifaunal assemblages. These substrates provide artificial habitats that mimic natural habitat features, thereby standardizing the sampling effort and enabling direct comparisons among different sites and studies. This paper explores the potential of the “Artificial Seaweed Monitoring System” (ASMS) sampling methodology to evaluate the natural variability of assemblages along a coastline of more than 200 km, by describing the succession of the ASMS’ associated macrofauna at two Rías of the Galician Coast (NW Iberian Peninsula) after 3, 6, 9, and 12 months after deployment. The results show that macrofauna assemblages harbored by ASMS differ between locations for every type of data. The results also support the hypothesis that succession in benthic communities is not a linear process, but rather a mixture of different successional stages. The use of the ASMS is proved to be a successful standard monitoring methodology, as it is sensitive to scale-dependent patterns and captures the temporal variability of macrobenthic assemblages. Hence, the ASMS can serve as a replicable approach contributing to the “Good Environmental Status” assessment through non-destructive monitoring programs based on benthic marine macrofauna monitoring, capturing the variability in representative assemblages as long as sampling deployment periods are standard.

Effects of structural complexity on epifaunal assemblages associated with two intertidal Mediterranean seaweeds

Brown foundation seaweeds are key elements increasing substrate heterogeneity and shaping the biodiversity in rocky coastal ecosystems. They are, however, vulnerable species that are declining due to multiple anthropogenic and climate change stressors, leading to a shift to less structural complex habitats. We investigate the role of structural attributes of two intertidal macroalgae, Ericaria amentacea and Laurencia obtusa, in shaping the abundance and diversity of their associated epifaunal assemblages. For this aim, we measured seaweeds’ biomass, thallus volume and length (used here as proxy of substrate complexity), and explored which seaweeds’ substrate attribute explained better variation of epifaunal assemblages. Results showed that E. amentacea was more complex than L. obtusa and hosted a higher number of epifaunal individuals. However, unlike that expected, the epifaunal assemblage of L. obtusa was more structured with higher Shannon–Wiener diversity and Pielous’ evenness. Our findings indicate that, besides seaweed’s substrate attributes, other mechanisms such as wave action and chemical defense might play a role in structuring epifaunal assemblages. We suggest that a shift from E. amentacea to L. obtusa population could have effect on structure and abundance of associated epifaunal assemblages. Certainly, further investigations are needed to clear up the consequences of these changes.

Seasonal effects of edge and habitat complexity on eelgrass epifaunal assemblages

Habitat degradation and fragmentation reduce habitat structural complexity (e.g. amount of physical features) and increase habitat edges. While many studies have focused on the effects of habitat edges or complexity on biodiversity, relatively few have disentangled them or investigated their effects over time. We investigated how proximity to the edge of eelgrassZosterasubg.Zostera marinaLinnaeus, 1753 habitat, shoot density and their interactions across seasons can influence the diversity pattern of epifaunal assemblages in meadows situated in a Mediterranean lagoon (France). We used a combination of field sampling andin situmanipulations with artificial seagrass units (ASUs) mimicking low and high shoot densities. During autumn and spring, we found that shoot density, Z. marina biomass and leaf area index (LAI) were higher inside the meadows than at the edge, while epiphyte load was the highest in spring at the edges. Epifaunal abundance and diversity were higher at the edge than inside the meadow for both natural shoots—regardless of the epiphyte load—and ASUs in spring. In autumn, epifaunal abundance varied positively with ASU density, regardless of the position in the meadow. Our results also showed that edges and habitat complexity affect the epifaunal structure differently across seasons. Therefore, we suggest that recruitment of macrofauna is the main mechanism explaining a positive edge effect during spring. This work highlights the need to consider seasonal dynamics in the assessment of habitat fragmentation and degradation.

Spatial distribution of benthic flora and fauna of coastal placentia bay, an ecologically and biologically significant area of the island of newfoundland, atlantic Canada

Coastal habitats have the potential to be biodiversity hotspots that provide important ecosystem services, but also hotspots for human development and exploitation. Continued use of coastal ecosystem services requires establishing baselines that capture the present state of the benthos. This study employs habitat mapping to establish a baseline describing the spatial distribution of benthic organisms along the western coast of Placentia Bay, an Ecologically and Biologically Significant Area (EBSA) in Newfoundland, Canada. The influence of seafloor characteristics on the distribution of four dominant epifaunal assemblages and two macrophyte species were modelled using two machine learning techniques: the well-established Random Forest and the newer Light Gradient Boosting Machine. When investigating model performance, the inclusion of fine-scale (<1 m) substrate information from the benthic videos was found to consistently improve model accuracy. Predictive maps developed here suggest that the majority of the surveyed areas consisted of a species-rich epifaunal assemblage dominated by ophiuroids, porifera, and hydrozoans, as well as prominent coverage by Agarum clathratum and non-geniculate crustose coralline algae. These maps establish a baseline that enables future monitoring of Placentia Bay’s coastal ecosystem, helping to conserve the biodiversity and ecosystem services this area provides.

A Tropical Macroalga (Halimeda incrassata) Enhances Diversity and Abundance of Epifaunal Assemblages in Mediterranean Seagrass Meadows

The introduction and successful expansion of tropical species into temperate systems is being exacerbated by climate change, and it is particularly important to identify the impacts that those species may have, especially when habitat-forming species are involved. Seagrass meadows are key shallow coastal habitats that provide critical ecosystem services worldwide, and they are threatened by the arrival of non-native macroalgae. Here, we examined the effects of Halimeda incrassata, a tropical alga that has recently colonized the Mediterranean Sea, on epifaunal assemblages associated with Cymodocea nodosa seagrass meadows of Mallorca Island (Western Mediterranean Sea). This invasive macroalga is an ecological engineer and thus has a high potential of modifying native habitats. A seagrass meadow colonized by H. incrassata exhibited important changes on associated epifaunal assemblages, with an increase in abundance and diversity, particularly driven by higher abundances of Gammaridae, Polychaeta, Copepoda and Caprellidae. Given the key ecological contribution of epifauna to food webs, these alterations will likely have important implications for overall food web structure and ecosystem functioning of native ecosystems.

Habitat‐complexity regulates the intensity of facilitation along an environmental stress gradient

Positive interactions between foundation species and their associated species are expected to be influenced by the degree of environmental stress as well as trait variations of the species involved. However, there is scarce empirical evidence regarding how these two factors interact and shape the intensity of facilitation. To test how facilitation varies with stress, a colonization experiment using artificial algal units that varied in a functional trait (morphological complexity) was conducted at different intertidal height levels. The isolated effects of shore‐height and host‐complexity are as expected: the number of species and overall abundance of epifauna decreased with lower complexity host units and greater exposure to environmental stress. However, in contrast to the initially proposed model, based on the stress gradient hypothesis, the magnitude of positive interactions increased at lower tidal heights (those levels with, presumably, milder environmental conditions). An additional predation exclusion experiment ruled out the effects of predation pressure as a major factor driving the structure of mobile epifaunal assemblages in these intertidal habitats. Thus, further studies are needed to identify the factors that explain the patterns of facilitation intensity found in the present study.

Diversity and time-series analyses of Caribbean deep-sea coral and sponge assemblages on the tropical island slope of Isla de Roat\xe1n, Honduras

Shore-based submersible operations, from 2006 to 2020, have allowed us to examine megabenthic assemblages along the island margin of Isla de Roatán from depths of about 150 to 750 m, including repeated observations of the same organisms. These dives were used to photo-document a diverse benthic assemblage and observe the health and condition of the sessile fauna in a well-explored but relatively undocumented area of the Mesoamerican Reef. Samples were collected by dip net, and some dives profiled the water column chemistry in the year 2011. The deep-sea coral assemblage observed off Roatan exhibits high abundance and diversity. The sessile habitat-forming taxa consist primarily of at least 20 different octocorals (e.g., Plexauridae, Primnoidae, Coralliidae, Isididae, and Ellisellidae) and 20 different sponges each (Demospongiae and Hexactinellida), with several known and unknown taxa of Zoantharia, Antipatharia (Bathypathes spp), and Scleractinia (e.g., Desmophyllum pertusum, Dendrophyllia alternata, Madracis myriaster, and solitary taxa). Crinoidea were also abundant and diverse, represented by at least nine species. Epifaunal assemblages associated with corals include at least 24 macroinvertebrate species dominated by Asteroschema laeve (Ophiuroidea) and Chirostylus spp. (Decapoda: Anomura). Repeated observations of a few large octocoral colonies over many years illustrate patterns of predation, recolonization, and epibiont host fidelity, including a 14-year record of decline in a plexaurid octocoral (putatively Paramuricea sp.) and loss of its resident ophiuroids. The shore-based submersible provides a practical and relatively inexpensive platform from which to study coral and sponge assemblages on a deep tropical island slope. The deep-sea coral gardens are likely to harbor new species and new discoveries if more samples can be acquired and made available for taxonomic research.

Structure and Trophic Niches in Mobile Epifauna Assemblages Associated With Seaweeds and Habitats of Syngnathid Fishes in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberia)

Syngnathids are vulnerable fishes closely associated with seaweeds and seagrass, which provide shelter and food resources. Even though most syngnathids commonly feed on small crustaceans, the feeding regimes may differ depending on the species and prey availability. This is the first monitoring study to explain syngnathid abundances and dietary regimes within macroalgal beds in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberian Peninsula). We sampled the epifaunal assemblages in seaweed communities dominated by the canopy-forming macroalgaeGongolaria baccataandCodiumspp. seasonally during 2 years. The epifaunal structure was mostly represented by harpacticoid copepods, amphipods (especially gammarids) and gastropods. Epifauna exhibited low plant-host specificity and a higher dominance of amphipods on the more structurally complex macroalgaeG. baccata.The epifaunal assemblages and syngnathid specimens were assessed for trophic structure using stable isotopes (δ13C and δ15N). The three syngnathids (Hippocampus guttulatus,Syngnathus acus, andEntelurus aequoreus) inhabiting Cíes Archipelago were sympatric. They occupied highly similar trophic positions (TPs), but differed in niche size, in such a way that the snake pipefishE. aequoreuswould likely feed on smaller prey. The assessment of the feeding regime in the dominant great pipefishS. acusrevealed that amphipods mostly contributed to bulk diet, followed by isopods, carideans, and copepods, whereas mysidaceans were not highly consumed. Seasonal changes in both epifaunal structure and syngnathids abundance confirmed that syngnathids are seasonal residents in Cíes Archipelago, migrating to other areas in autumn when the seaweed cover is drastically reduced and the epifaunal structure modified. This study showed the importance ofGongolariaassemblages in Cíes Archipelago, providing rich dietary sources and potentially contributing to higher abundances and diversity of syngnathids. Ongoing cover reduction inGongolariaassemblages in certain regions (e.g., Mediterranean) should be considered a potential ecological concern for syngnathids and accompanying fauna, requiring further investigations.

The invasive seaweed Asparagopsis taxiformis erodes the habitat structure and biodiversity of native algal forests in the Mediterranean Sea

Invasive seaweeds are listed among the most relevant threats to marine ecosystems worldwide. Biodiversity hotspots, such as the Mediterranean Sea, are facing multiple invasions and are expected to be severely affected by the introduction of new non-native seaweeds in the near future. In this study, we evaluated the consequences of the shift from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis habitat on the shallow rocky shores of Favignana Island (Egadi Islands, MPA, Sicily, Italy). We compared algal biomass and species composition and structure of the associated epifaunal assemblages in homogenous and mixed stands of E. brachycarpa and A. taxiformis. The results showed that the biomass of primary producers is reduced by 90% in the A. taxiformis invaded habitat compared to the E. brachycarpa native habitat. The structure of the epifaunal assemblages displayed significant variations among homogenous and mixed stands. The abundance, species richness and Shannon-Wiener diversity index of the epifaunal assemblages decreased by 89%, 78% and 40%, respectively, from homogenous stands of the native E. brachycarpa to the invasive A. taxiformis. Seaweed biomass was the structural attribute better explaining the variation in epifaunal abundance, species richness and diversity. Overall, our results suggest that the shift from E. brachycarpa to A. taxiformis habitat would drastically erode the biomass of primary producers and the associated biodiversity. We hypothesize that a complete shift from native to invasive seaweeds could ultimately lead to bottom-up effects on rocky shore habitats, with negative consequences for the ecosystem structure, functioning, and the services provided.

Differential tolerance of species alters the seasonal response of marine epifauna to extreme warming

Marine heatwaves are occurring with greater frequency and magnitude worldwide and can significantly alter community structure and ecosystem function. Predicting changes in community structure in extreme temperatures requires an understanding of variation among species in their thermal tolerance, and how potential acclimatization to recent temperatures influences survival. To address this, we determined the tolerance to extreme temperatures in a crustacean epifaunal assemblage that inhabits macroalgae in the southeast Australian ocean warming hotspot. Amphipods were the most abundant group and the thermal tolerance of the most abundant species (two in winter and four in summer) was tested to determine their thermal limits and probability of survival in near-future extreme temperatures. Survival, measured as time to immobilization, was compared across species, sexes, life stage and body size. The greatest variation in tolerance to extreme temperatures was among species (not body sizes or life stages), indicating that heatwaves could shift the composition of the macroalgal associated epifaunal assemblage. Comparison of recent thermal history (between 18 °C to 22 °C) revealed greater thermal tolerance of warm acclimatized individuals. Our results indicate that the impacts of a marine heatwave will depend on local species composition and their timing relative to recent climate conditions.

Evaluating the vulnerability of coralligenous epifauna to macroalgal invasions

Abstract This work constitutes the first comprehensive study of the epifaunal response to biological invasions in coralligenous habitats, which are one of the main hotspots of biodiversity in the Mediterranean. The epifaunal community inhabiting the invasive macroalga Rugulopteryx okamurae and other dominant sessile hosts on coralligenous habitats (i.e. the sponge Spongia lamella, the gorgonian Paramuricea clavata, and the macroalga Sphaerococcus coronopifolius) was characterized. A total of 137 taxa were found. There was a lack of functional equivalence between macroalgal species (both native and invasive) and sessile invertebrates. Despite the absence of significant differences in mean density values and number of species per replicate among host species, epifaunal composition on gorgonians and sponges differed significantly from that on both macroalgae. Epifaunal assemblages, especially those inhabiting macroalgal species, were dominated by generalist detritivorous species that can inhabit different hosts, while specialized interactions between mobile epifauna and sessile hosts were observed almost exclusively on sessile invertebrates. Moreover, epifaunal community associated with invertebrate hosts showed higher spatial heterogeneity in comparison with native and invasive macroalgae. A competitive displacement of native hosts by the spreading of R. okamurae on coralligenous habitats would likely result in a biotic impoverishment in terms of overall number of species and a taxonomical and functional homogenization of the epifaunal community. Specialist species with a heterogeneous distribution could be gradually replaced by a spatially homogeneous assemblage dominated by generalist species.

High biomass and productivity of epifaunal invertebrates living amongst dead coral

Climate change is transforming coral reef structures, with important yet largely unknown consequences for reef food webs. Crustaceans, molluscs, polychaetes, and other small motile invertebrates living as epifauna on coral habitats represent an essential trophic link between primary producers and a diverse and abundant invertivorous fish fauna. Here, we investigate variation in assemblages of motile epifaunal invertebrates on live coral and dead coral heavily overgrown by turf algae. Sampling was conducted 2–3 years following mass bleaching within the study region at four locations broadly spanning the distribution of corals on the eastern seaboard of Australia—along the northern and central Great Barrier Reef, and, adjacent to the central east coast, the Solitary Islands and offshore Elizabeth and Middleton Reefs (> 2000 km total distance). Epifaunal assemblages differed significantly between live and dead ‘turf-covered’ coral habitats, with overall density, biomass, and productivity of epifauna more than an order of magnitude greater on dead than on live coral. The size structure and composition of assemblages also differed: turf-covered dead coral supported greater abundances of small animals than live coral, notably harpacticoid copepods, while live coral assemblages had proportionally greater abundances of larger decapods. A ten-fold increase in secondary productivity of motile invertebrates is predicted as live corals are replaced by turf-covered dead coral, however, this productivity will predominantly be available as small harpacticoid copepod prey (size range: 0.125–0.25 mm). Associated flow-on effects through reef food webs are likely, as changes to epifauna will directly affect invertivore communities, which in turn potentially influence larger carnivores and other functional groups.

Does the invasive macro-algae Sargassum muticum (Yendo) Fensholt, 1955 offer an appropriate temporary habitat for mobile fauna including non indigenous species?

The fauna inhabiting the brown seaweed Sargassum muticum was studied on a spatial scale along the Normandy coast from the Normand-Breton Gulf to the Bay of Seine (English Channel) in both shallow sandy and rocky tidal pools during the springs 2018 and 2019. In this paper, we test the following hypothesis: do the areas with dense populations of S. muticum represent an appropriate habitat for dense motile fauna including other Non-Indigenous Species (NIS)? The ALEX (ALien biotic indEX) is used to ascertain whether or not S. muticum favours the establishment of other NIS in this new habitat. Results show that the epifaunal assemblage associated with S. muticum differs between the five sampling sites. However, the fauna at all five sites is dominated by arthropoda, especially the amphipods and isopods. In addition, five non indigenous species are observed inhabiting the brown seaweed (four amphipods: Aoroides longimerus, Aoroides semicurvatus, Monocorophium acherusicum, Monocorophium sextonae and one decapod: Hemigrapsus sanguineus). In spite of the presence of Non-Indigenous Species (NIS) associated with the invasive Sargassum, the ALEX yields a high Ecological Quality Status for all the sites. Nevertheless, the results suggest that S. muticum is a suitable habitat for many invertebrates especially amphipods and isopods, while also representing a potential source of food for several local fish and cephalopod species.

Small invertebrate consumers produce consistent size spectra across reef habitats and climatic zones

Changes in invertebrate body size‐distributions that follow loss of habitat‐forming species can potentially affect a range of ecological processes, including predation and competition. In the marine environment, small crustaceans and other mobile invertebrates (‘epifauna') represent a basal component in reef food webs, with a pivotal secondary production role that is strongly influenced by their body size‐distribution. Ongoing degradation of reef habitats that affect invertebrate size‐distributions, particularly transformation of coral and kelp habitat to algal turf, may thus fundamentally affect secondary production. Here we explored variation in size spectra of shallow epifaunal assemblages (i.e. the slope and intercept of the linear relationship between log abundance and body size at the assemblage level) across 21 reef microhabitats distributed along an extensive eastern Australian climatic gradient from the tropical northern Great Barrier Reef to cool temperate Tasmania. When aggregated across microhabitats at the site scale, invertebrate body size spectra (0.125–8 mm range) were consistently log‐linear (R2 ranging 0.87–0.98). Size spectra differed between, but not within, major groups of microhabitats, and exhibited little variability between tropical and temperate biomes. Nevertheless, size spectra showed significant tropical/temperate differences in slopes for epifauna sampled on macroalgal habitats, and in elevation for soft coral and sponge habitats. Our results reveal epifaunal size spectra to be a highly predictable macro‐ecological feature. Given that variation in epifaunal size spectra among groups of microhabitats was greater than variation between tropical and temperate biomes, we postulate that ocean warming will not greatly alter epifaunal size spectra directly. However, transformation of tropical coral and temperate macroalgal habitats to algal turfs due to warming will alter reef food web dynamics through redistribution of the size of prey available to fishes.

Multiple stressors and disturbance effects on eelgrass and epifaunal macroinvertebrate assemblage structure

Multiple forms of environmental change and anthropogenic pressure co-occur in coastal marine ecosystems. These external forces affect ecosystem structure, functioning, and, eventually, services to humans. Studies that include more than 2 simultaneous stressors are still needed to understand potential interactions among multiple stressors. We evaluated single and interactive effects of density reduction of Zostera marina L. (a habitat-forming species), shading, and sediment nutrient enrichment on the response of Z. marina and its associated epifauna over 10 wk. Shading had the greatest effect on reducing the eelgrass relative leaf elongation rate (RLE), non-structural carbohydrate reserves, and eelgrass shoot density. A reduced eelgrass density sustained higher epifaunal densities and increased the eelgrass RLE. Sediment nutrient enrichment increased eelgrass shoot density but decreased epifaunal richness, diversity, and total abundance. Our disturbance and pair of stressors differed in their influence on diversity measures, but all affected assemblage structure. Most of the changes to the epifaunal assemblage and diversity likely occurred due to altered habitat availability and epiphytic algae load. We observed additive, antagonistic, and negatively synergistic interactions among our treatments, while most of the cumulative effects showed dominance by one stressor over another. Our results highlight the importance of field experiments that are based on multiple disturbances and stressors to determine their interaction type on communities.

Feeding ecology of pipefish species inhabiting Mediterranean seagrasses

Pipefish are a vulnerable and diverse group of ichthyofauna tightly associated to seagrass meadows, key habitats in shallow marine areas. Despite of their charismatic role, main ecological features, habitat and diet of this group remain largely unknown. This study focuses on assessing pipefish habitat and feeding preferences including different hosting seagrasses such as Posidonia oceanica and Cymodocea nodosa from the Balearic Islands, western Mediterranean. Four species (Syngnathus typhle, S. abaster, Nerophis ophidion and N. maculatus) were found associated to different seagrasses. S. typhle and N. maculatus were more frequent in P. oceanica meadows, while S. abaster and N. ophidion in C. nodosa. Individuals of all species captured in P. oceanica were larger than those living in C. nodosa, suggesting a size-dependent habitat preference. Feeding preferences, however, were driven by prey availability and fish features, e.g head/snout morphology. For the first time in the western Mediterranean, a thorough description of the diet and potential preys of this group was carried out. Epifaunal assemblages (potential prey) were dominated in both habitats by harpacticoid copepods and gammarid amphipods, and they were also the primary preys according to stomach contents of all species. These results can contribute to future pipefish conservation and management actions, such as targeting crucial habitat identification and designing culture and reintroduction protocols.

Spatiotemporal variation of the epifaunal assemblages associated to Sargassum muticum on the NW Atlantic coast of Morocco.

Epifaunal assemblages inhabiting the non-indigenous macroalga Sargassum muticum (Yendo) Fensholt were investigated on two physically distinct intertidal rocky (S1) and sandy (S2) sites along the Atlantic coast of Morocco. The objective of this study was to test whether the habitat-forming marine alga S. muticum invasive in these sites supported different epifaunal assemblages under different environmental conditions and through time. The gastropods Steromphala umbilicalis, S. pennanti, and Rissoa parva and the isopod Dynamene bidentata were the most contributive species to the dissimilarity of epifaunal assemblage structure between both sites throughout seasons. SIMPER analysis showed a dissimilarity of 58.3-78.5% in the associated species composition of S. muticum between study sites with respect to sampling season. Species diversity and total abundance were significantly higher at the rocky site compared to the sandy site. PERMANOVA analyses showed significant differences of associated epifaunal assemblage structure for the season and site interaction. Accordingly, site and season were determinant factors conditioning the role of habitat in structuring epifaunal assemblages.

Epifaunal invertebrate assemblages associated with branching Pocilloporids in Moorea, French Polynesia.

Reef-building corals can harbour high abundances of diverse invertebrate epifauna. Coral characteristics and environmental conditions are important drivers of community structure of coral-associated invertebrates; however, our current understanding of drivers of epifaunal distributions is still unclear. This study tests the relative importance of the physical environment (current flow speed) and host quality (e.g., colony height, surface area, distance between branches, penetration depth among branches, and background partial mortality) in structuring epifaunal communities living within branching Pocillopora colonies on a back reef in Moorea, French Polynesia. A total of 470 individuals belonging to four phyla, 16 families and 39 genera were extracted from 36 Pocillopora spp. colonies. Decapods were the most abundant epifaunal organisms (accounting for 84% of individuals) found living in Pocillopora spp. While coral host characteristics and flow regime are very important, these parameters were not correlated with epifaunal assemblages at the time of the study. Epifaunal assemblages associated with Pocillopora spp. were consistent and minimally affected by differences in host characteristics and flow regime. The consistency in abundance and taxon richness among colonies (regardless of habitat characteristics) highlighted the importance of total habitat availability. With escalating effects of climate change and other localized disturbances, it is critical to preserve branching corals to support epifaunal communities.