Epiphytic Invertebrates Research Articles

Varying Responses of Invertebrates to Biodynamic, Organic and Conventional Viticulture

Alternative farming methods must be deployed to mitigate the detrimental impacts of intensive agriculture on climate, biodiversity, and ecosystem services. Organic and biodynamic farming are environmental-friendly practices that progressively replace conventional agriculture. While potential biodiversity benefits of organicvs. conventional farming have been studied repeatedly, the effects of biodynamic farming on biodiversity remain ill-understood. We investigated the effects of these three main management regimes, and their interaction with ground vegetation cover, on vineyard invertebrate communities in SW Switzerland. Invertebrates were sampled three times during the vegetation season in 2016, focusing on ground-dwelling (pitfall traps) and epiphytic (sweep-netting) invertebrates, and their abundance was modelled for single, additive, and interactive influences of management and ground vegetation cover. Overall, organic and, but to a lesser degree, biodynamic vineyards provided better conditions for invertebrate abundance than conventional vineyards. On the one hand, there was a significant interaction between management and ground vegetation cover for epiphytic invertebrates with a positive linear increase in abundance in organic, a positive curvilinear relationship in biodynamic but a negative curvilinear response to vegetation cover in conventional vineyards. The abundance of ground-dwelling invertebrates was primarily affected by the management regime alone, i.e. without any interaction with ground vegetation characteristics, leading to much higher abundances in organic compared to conventional vineyards, while biodynamic did not differ from the other two regimes. We interpret the patterns as follows: organic grape production offers more suitable habitat conditions for invertebrates due to a spatially more heterogenous but also less often disturbed (compared to biodynamic management) or destroyed (compared to conventional) ground vegetation cover, in line with the predictions of the intermediate disturbance hypothesis. Biodynamic and conventional viticultural management regimes often provide a habitat that is either too mineral (conventional: ground vegetation widely eliminated) or subject to soil disturbance happening frequently through ploughing (biodynamic). We conclude that alternative farming methods do promote biodiversity in vineyard agro-ecosystems, especially so organic management.

Sharing the neighbourhood: assessing the impact of kelp harvest on foraging behaviour of the European shag

Coastal kelp forest ecosystems create dynamic and productive habitats, supporting a wide range of epiphytic flora, invertebrates, fish and seabirds. Worldwide, kelp is harvested commercially, affecting kelp-associated animal communities. There is, however, limited knowledge of how fish and seabird respond to kelp harvest, highlighting the need to evaluate the ecological impact of harvest on all ecosystem levels. Using 6 years of GPS-tracking data, we examined the effects of kelp harvest on foraging behaviour of breeding European shags (Phalacrocorax aristotelis) from a colony in central Norway. We determined the spatial overlap between kelp harvest and foraging areas of shags and assessed the immediate, short- and long-term impacts of harvest on shag foraging behaviour. Our results demonstrated large spatial and temporal overlap in areas used by foraging shags and kelp harvest. We could not detect any clear alterations in the diving activity of shags due to kelp harvest. However, the broad temporal and spatial scale of our study constrained the detection of fine scale changes in shag behaviour in response to kelp harvest. Our study, nonetheless, identifies several issues that should be addressed before concluding on the effects of kelp harvest on seabird populations. This includes the need for experimental studies using directed and controlled harvest to investigate the effects of kelp harvest through the different trophic levels, including top predators. This is essential for ecosystem-based management of coastal resources, considering the many species composed in the coastal ecosystem.

Effects of macroalgal morphology on marine epifaunal diversity

AbstractMacroalgae play important ecological roles, including as hosts for a wide range of epifauna. However, the diversity relationships between macroalgae and epifauna are poorly understood for most tropical host species and algal morphologies. This study aims to characterize and analyse the diversity of invertebrates present amongst macroalgae with three distinct morphologies (three-dimensional, filamentous and foliose) across different tropical intertidal sites in Singapore. Morphological and DNA barcoding tools were employed for epifaunal species identification, and ordination statistics and multiple linear regression were used to test the effects of algal morphology, species and site on community structure and diversity of epiphytic invertebrates. Overall, epifaunal communities were distinct among sites and algal morphologies, and diversity was affected significantly by algal morphology. In particular, filamentous macroalgae hosted the highest abundance of epifauna dominated mainly by amphipods, which were able to take advantage of the high surface area to volume ratio in filamentous algal mats as a consequence of their thinner forms. Foliose species showed a significantly negative effect on invertebrate diversity. Our findings highlight the diverse associations between intertidal macroalgae and invertebrates with high turnover between algal morphology and sites that contribute to the high biodiversity of tropical shores. Future studies should consider the effects of the host habitat, seasonality and more algal species on epifaunal diversity.

The distribution and mitochondrial genotype of the hydroid Aglaophenia latecarinata is correlated with its pelagic Sargassum substrate type in the tropical and subtropical western Atlantic Ocean.

The pelagic brown macroalga Sargassum supports rich biological communities in the tropical and subtropical Atlantic region, including a variety of epiphytic invertebrates that grow on the Sargassum itself. The thecate hydroid Aglaophenia latecarinata is commonly found growing on some, but not all, Sargassum forms. In this study, we examined the relationship between A. latecarinata and its pelagic Sargassum substrate across a broad geographic area over the course of 4 years (2015–2018). The distribution of the most common Sargassum forms that we observed (Sargassum fluitans III and S. natans VIII) was consistent with the existence of distinct source regions for each. We found that A. latecarinata hydroids were abundant on both S. natans VIII and S. fluitans III, and also noted a rare observation of A. latecarinata on S. natans I. For the hydroids on S. natans VIII and S. fluitans III, hydroid mitochondrial genotype was strongly correlated with the Sargassum substrate form. We found significant population genetic structure in the hydroids, which was also consistent with the distributional patterns of the Sargassum forms. These results suggest that hydroid settlement on the Sargassum occurs in type-specific Sargassum source regions. Hydroid species identification is challenging and cryptic speciation is common in the Aglaopheniidae. Therefore, to confirm our identification of A. latecarinata, we conducted a phylogenetic analysis that showed that while the genus Aglaophenia was not monophyletic, all A. latecarinata haplotypes associated with pelagic Sargassum belonged to the same clade and were likely the same species as previously published sequences from Florida, Central America, and one location in Brazil (São Sebastião). A nominal A. latecarinata sequence from a second Brazilian location (Alagoas) likely belongs to a different species.

Effects of Epiphytes and Depth on Seagrass Spectral Profiles: Case Study of Gulf St. Vincent, South Australia.

Seagrasses are a crucial indicator species of coastal marine ecosystems that provide substratum, shelter, and food for epiphytic algae, invertebrates, and fishes. More accurate mapping of seagrasses is essential for their survival as a long-lasting natural resource. Before reflectance spectra could properly be used as remote sensing endmembers, factors that may obscure the detection of reflectance signals must be assessed. The objectives in this study are to determine the influence of (1) epiphytes, (2) water depth, and (3) seagrass genus on the detection of reflectance spectral signals. The results show that epiphytes significantly dampen bottom-type reflectance throughout most of the visible light spectrum, excluding 670–679 nm; the depth does influence reflectance, with the detection of deeper seagrasses being easier, and as the depth increases, only Heterozostera increase in the exact “red edge” wavelength at which there is a rapid change in the near-infrared (NIR) spectrum. These findings helped improve the detection of seagrass endmembers during remote sensing, thereby helping protect the natural resource of seagrasses.

Diversity of planktonic and epiphytic microinvertebrates associated with the macrophyte Eichhornia crassipes (Mart.) in River Nile at El-Qanater El-Khiria region, Egypt

The present work aims to study the relationship between some physico-chemical parameters and both planktonic and epiphytic microinvertebrates associated with the floating plant Eichhornia crassipes in River Nile at Qanater region. Water samples, planktonic and epiphytic microinvertebrates were collected seasonally from eight sites in the investigated region. The results indicated that the maximum occurrence of planktonicinvertebrates (810 org./L) was recorded during Winter. Rotifera formed the highest percentage of zooplankton (96.77 %), followed by Copepoda (1.88 %) and Cladocera (1.10 %). Meroplankton and Protozoa formed the lowest dominant groups. Thirty seven planktonicspecies were recorded belonging to Rotifera (30 species), Cladocera (2 species), Copepoda (1 species), Protozoa (2 species) and Meroplankton (2 species). On the other hand, the maximum occurrence of epiphytic invertebrates (1612100 org./m2 plant) was recorded during spring. Forty five species were recorded belonging to Rotifera (27 species), Protozoa (5 species), Cladocera (9 species), Copepoda (2 species) and Oligochaeta (2 species). The epiphytic microinvertebrates associated with the floating plant Eichhornia crassipes in River Nile at Qanater region recorded the highest number of species and groups than planktonic invertebrates. This indicates that the aquatic plant Eichhornia crassipes habitats are more diverse and have high species richness. The principal component analysis (PCA) was conducted between physico-chemical parameters and planktonic and microinvertebrates.

Epiphytic invertebrate patterns in coastal lakes along a gradient of salinity and water exchange with the sea

The species composition and abundance of epiphytic fauna inhabiting common reed (Phragmites australis (Cav.) Trin. ex Steud.) was performed in five coastal lakes in Słowiński National Park (southern Baltic coast in northern Poland). The lakes represent a salinity gradient (from freshwater to β-oligohaline waters) and four types of coastal lakes: (1) lagoon, L (Lake Łebsko, seawater enters it permanently); (2) coastal lake with periodically brackish water, CLB (Lake Gardno); (3) freshwater costal lake, CLF (Lake Smołdzińskie); and (4) coastal dune lakes, CLD (Dołgie Wielkie and Dołgie Małe). Using statistical ordination techniques, we found that the structure of epiphytic fauna (microinvertebrates and macroinvertebrates) is determined primarily by hydrological connectivity (water exchange) with the sea. Canonical Correspondence Analysis, coupled with variance partitioning, showed that hydrological connectivity accounted for 24% of the variation in the invertebrate community, followed by physico-chemical (19%) and trophic (8%) factors. Our results indicate that the assemblages of Ciliata-libera and Cnidaria are characteristic for L (β-oligohaline), Rotifera, Suctoria, Chaetogaster sp., Gastropoda and Trichoptera are characteristic for CLB (limnetic/β-oligohaline), but no taxonomic groups are characteristic for CLF and CLD (both limnetic). The index of multivariate dispersion showed a decreasing trend with the increasing lake isolation from the open sea, except for CLD. However, in terms of the structure of epiphytic fauna, Multi-Response Permutation Procedures showed that CLD significantly differed only from CLB. Our results suggest that the identified characteristic taxonomic groups of plant-associated macroinvertebrates have a high potential to be used as bioindicators of salinity and water exchange with the sea, due to their sensitivity to environmental stress.

Does Dredging of Floodplain Lakes Affects The Structure of The Macrophytes and Epiphytic Fauna Inhabiting Stratiotes Aloides?

Hydrotechnical activities on the Slupia river above the town of Slupsk (northern Poland) were performed against floods in the valley. The results based on the data on fauna and flora gathered before (in 2003, T +0 ) and after (in T +2 , T +6 and T +11 ) the reclamation showed that the river canalization and oxbow lake dredging can significantly disturb the ecology of water bodies adjacent to the river. Observations of the oxbow lake (OLS5), showed the decrease in the number of macrophyte phytocenoses from 11 before the dredging to 6 very valuable Potametea phytocenoses , after wards. The development of common pleustonic phytocenoses of Lemnetea minoris and the massive development of green algae resulted from the bottom sediment removal. In the case of population, Stratiotes aloides was rebuilt after elimination during dredging already in T +2 . Before hydrotechnical works, the oxbow lake was characterized by 12 invertebrate taxa inhabiting S.aloides , whereas only 9 were found first period after the dredging, 15 taxa in second period and 23 in a recent study. During both observation periods, dominated by Chironomidae larvae (T +0 ), Trichoptera larvae (T +2 and T +6 ) and again Chironomidae larvae (T +11 ). The hydrotechnical activities significantly altered in the first period the structure of fauna and flora inhabiting the water body. Such radical interference in natural values of oxbow lakes is un-suitable for the preservation of ecosystems due to the significant decrease in their biodiversity. Achieved on a similar or higher level of macrophytes diversity and epiphytic invertebrates was noticeable ten years after the dredging of a water body.

Multi‐trophic impacts of an invasive aquatic plant

Summary Natural resource agencies are increasingly required to prioritise management of multiple non‐native aquatic plants (macrophytes) in freshwater ecosystems. Characterising the consequences of invasions for ecological processes and corresponding ecosystem services is fundamental to this decision‐making process, but requires an understanding of impacts across physical, chemical, and biological responses. Accordingly, we evaluated the multi‐trophic impacts of the invasive macrophyte Myriophyllum aquaticum (Haloragaceae; parrotfeather) along the mainstem Chehalis River, Washington, U.S.A. We examined invertebrate, plant and fish community responses to varying degrees of parrotfeather abundance and simultaneously characterised variation in physical structure and dissolved oxygen (DO) across the dominant native and non‐native plant species. DO concentrations were significantly reduced and approached hypoxic levels in areas dominated by parrotfeather compared with native vegetation. Increased structural complexity, volume and biomass of parrotfeather was associated with increased diversity of epiphytic invertebrates. However, these more diverse invertebrate assemblages were dominated by amphipods, whereas native macrophytes were characterised by cladocerans, chironomids and gastropods. Non‐native fishes (primarily centrarchid species) were more strongly associated with sites where parrotfeather was present and diversity of non‐native fishes was positively correlated along a gradient of parrotfeather abundance. Native fish associated with parrotfeather areas were those that tend to be tolerant of degraded or lower quality habitats. We saw little evidence of exclusion of other macrophytes; native and non‐native plant diversity and abundance were positively correlated with the parrotfeather gradient. This may reflect that analysis was done at a site level, and competitive dominance might be apparent by changes in species richness at smaller (plot) scales or over longer periods. Alternatively, parrotfeather may demonstrate minimal effects on native plant composition. Given the effects observed across multiple habitat characteristics and biota, parrotfeather appears to be a highly impactful invader where it establishes. Many of the changes we observed appear to derive from the emergent leaves and dense mat formation of parrotfeather compared with a submersed structure more typical of the native community. Our results suggest that managers should specifically consider contrasting characteristics between non‐native and native physical structure when assessing and prioritising threats of invasive macrophytes.

Macroinvertebrate responses to regime shifts caused by eutrophication in subtropical shallow lakes

The ecological status of subtropical floodplain lakes is threatened by eutrophication, which can shift lakes from a clear, macrophyte-dominated equilibrium state to a turbid, phytoplankton-dominated state. Such a shift is reflected in their macroinvertebrate assemblages, which may serve as good indicators of long-term changes in such lake ecosystems. We conducted a survey of benthic macroinvertebrates in 20 lakes in the Yangtze floodplain that were disconnected from the river channel to identify invertebrate response patterns along a gradient of eutrophication. Macroinvertebrate assemblages changed in parallel to the observed regime shift of a subgroup of those lakes. The most abundant groups were epiphytic invertebrates (e.g., Bithyniidae) in the macrophyte-dominated lakes and pollution-tolerant invertebrates (e.g., Tubificidae, Tanypus) in the phytoplankton-dominated lakes. Planktonic chlorophyll a concentration and wet biomass of submersed macrophytes were the key factors structuring macroinvertebrate assemblages. Macroinvertebrate taxon richness decreased along the eutrophication gradient, but density reached a minimum at a moderate eutrophication level and then increased. Scraper density (e.g., Bithyniidae) dropped abruptly at the moderate eutrophication level and did not increase again, whereas collector–gatherers (mainly Tubificidae and Chironomidae) and predators (e.g., Tanypus) increased continuously along the eutrophication gradient. We conclude that the abrupt disappearance of macrophytes during the regime shift means the loss of key habitat for biota associated with aquatic plants. Therefore, ecological restoration projects should be designed to reduce the nutrient concentration of floodplain lakes enough to allow re-establishment of a clear-water lake equilibrium dominated by aquatic macrophytes.

Open Structured Woodland and the Ecological Interpretation of Scotland's Ancient Woodland Inventory

ABSTRACTFollowing intensive human land use over millennia, European forest ecosystems record among the largest values of deforestation globally. This puts a premium on European ancient woodland, which has existed in the landscape minimally over several centuries. Ancient woodland in the UK was quantified in the Ancient Woodland Inventory (AWI). In cross-checking AWI sites in Scotland, it came to our attention that a proportion of ‘Class 3’ woodlands, which are thought to be of recent origin (regenerated since the nineteenth century), retain scattered tree symbols. This paper quantifies the degree to which Class 3 AWI sites may correspond to areas of scattered trees or open growth woodland. We show that a significant number (c. 50%) of Class 3 sites appear to have continuity of tree/woodland habitat; this may be particularly important for interpreting the distribution of ecological guilds such as tree-dependent epiphytic lichens and invertebrates. The study serves to re-emphasise that (i) technological limits and priorities of map makers, (ii) value systems of historical geographers, and (iii) biology of species, should be carefully considered and aligned during ecological research, so that potential anomalies, for example, the continuous existence of open structured woodland, can be fully recognised during application of systems such as the AWI.

Response of rocky invertebrate diversity, structure and function to the vertical layering of vegetation

Macroalgae comprise a prominent part of the rocky benthos where many invertebrates develop, and are believed to be undergoing severe declines worldwide. In order to investigate how the vegetation structure (crustose, basal and canopy layers) contributes to the diversity, structure and function of benthic invertebrates, a total of 31 subtidal transects were sampled along the northeast Atlantic coast of Spain. Significant positive relationships were found between the canopy layer and faunal abundance, taxonomic diversity and functional group diversity. Canopy forming algae were also related to epiphytic invertebrates, medium size forms, colonial strategy and suspensivores. By contrast, basal algae showed negative relationships with all variables tested except for detritivores. Multivariate multiple regression analyses (DISTLM) point to crustose as well as canopy layers as the best link between seaweeds and invertebrate assemblage structure. A close relationship was found between taxonomic and functional diversities. In general, low levels of taxonomic redundancy were detected for functional groups correlated with vegetation structure. A conceptual model based on the results is proposed, describing distinct stages of invertebrate assemblages in relation to the vertical structure of vegetation.

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.

Epiphytic seaweeds and invertebrates associated with South African populations of the rocky shore seagrass Thalassodendron leptocaule — a hidden wealth of biodiversity

Seagrasses support a great diversity of epiphytic organisms. There are no detailed published accounts of algae and animals growing on seagrasses in South Africa. The seagrass Thalassodendron leptocaule (previously known as Thalassodendron ciliatum) is unique among southern African seagrasses in that it occurs on exposed rocky outcrops along the Mozambican and north-eastern South African coasts; most other seagrasses are restricted to sheltered bays and estuaries. Here we present accounts of species of flora and fauna identified growing epiphytically on this seagrass in northern KwaZulu-Natal. A total of 52 taxa of macroalgae and 204 species of macroinvertebrates were identified as epiphytic on South African T. leptocaule. The most frequently observed macroalgal epiphytes were predominantly Rhodophyta and were common among periodically exposed, intertidal and subtidal habitats. The crustose red coralline algae Pneophyllum amplexifrons and Hydrolithon farinosum were frequently observed, primarily on stems and leaves of the seagrass respectively. The most diverse groups of epiphytic invertebrates were Arthropoda, Annelida and Mollusca, which together comprised 76% of the macroinvertebrate species recorded. This seagrass species is evidently an important substratum and ecosystem that supports a hidden wealth of biodiversity.

Coral reef fish association with macroalgal beds on a tropical reef system in North-eastern Brazil

Macroalgal beds are recognised for their role as nursery and feeding grounds for several marine species. This study was conducted in the Tamandaré reef complex within the limits of the Costa dos Corais Marine Protected Area (MPA), North-eastern Brazil. The macroalgal bed studied is subjected to several disturbances, especially from tourism. The reef fish were assessed with free dives during the day and night using visual censuses within transects (20 × 2 m) and random swims. The percentage algal cover was estimated using quadrats (40 cm2). The behavioural traits of the fish also provided an understanding of their habitat use. In total, 68 fish species were recorded. The most abundant species were representatives of the families Labridae, Pomacentridae, Acanthuridae and Haemulidae. Sargassum polyceratium, Dictyopteris delicatula and Canistrocarpus cervicornis were the most abundant macroalgae. Because the most abundant fish trophic guild included primarily mobile invertebrate feeders (41.8%) and carnivores (28.4%), it is suggested that the high-canopy macroalgae harbour epiphytic invertebrates, which these fish use for food. Thereby, the study area would act as important nursery and feeding grounds. Tourism activity (e.g. laying chairs, trampling and anchoring) may disrupt fish behaviour and life- history traits and result in damage that would require mitigation through environmental awareness and law enforcement in the most affected areas.

Ecological and socio‐economic impacts of invasive water hyacinth (Eichhornia crassipes): a review

Summary1. Water hyacinth (Eichhornia crassipes) is one of the world’s most invasive aquatic plants and is known to cause significant ecological and socio‐economic effects.2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants.3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability.4. Effects of water hyacinth on fish are largely dependent on original community composition and food‐web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels.5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density.6. The socio‐economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem‐level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic‐levels are needed to further our understanding of invasive species.

Epiphytic macroinvertebrate communities on Eurasian watermilfoil (Myriophyllum spicatum) and native milfoils Myriophyllum sibericum and Myriophyllum alterniflorum in eastern North America

Aquatic macrophytes play an important role in the survival and proliferation of invertebrates in freshwater ecosystems. Epiphytic invertebrate communities may be altered through the replacement of native macrophytes by exotic macrophytes, even when the macrophytes are close relatives and have similar morphology. We sampled an invasive exotic macrophyte, Eurasian watermilfoil ( Myriophyllum spicatum ), and native milfoils Myriophyllum sibericum and Myriophyllum alterniflorum in four bodies of water in southern Quebec and upstate New York during the summer of 2005. Within each waterbody, we compared the abundance, diversity, and community composition of epiphytic macroinvertebrates on exotic and native Myriophyllum. In general, both M. sibericum and M. alterniflorum had higher invertebrate diversity and higher invertebrate biomass and supported more gastropods than the exotic M. spicatum. In late summer, invertebrate density tended to be higher on M. sibericum than on M. spicatum, but lower on M. alterniflorum than on M. spicatum. Our results demonstrate that M. spicatum supports macroinvertebrate communities that may differ from those on structurally similar native macrophytes, although these differences vary across sites and sampling dates. Thus, the replacement of native milfoils by M. spicatum may have indirect effects on aquatic food webs.

Density and distribution of epiphytic invertebrates on emergent macrophytes in a floodplain billabong

AbstractThe abundance of epiphytic invertebrates living on both submerged and emergent macrophytes in lentic systems is influenced by a range of environmental features at both spatial and temporal scales. Such features include water chemistry, habitat complexity, hydrology and external influences such as climatic cycles. Dugays 2 billabong is a floodplain lake on the highly regulated, mid‐upper Murray River in southeastern Australia. Giant rush (Juncus ingens N.A. Wakefield) is the dominant habitat feature in this billabong. This plant is a simple, single‐stemmed, densely packed emergent macrophyte that fringes the littoral margins. The macrophyte habitat available to epiphytic invertebrates in this billabong is highly variable through time largely due to the variable water levels imposed by the regulated river channel for downstream irrigation needs, particularly through summer. To investigate both spatial and temporal patterns in the epiphytic invertebrates of Dugays 2 billabong, invertebrates were sampled within giant rush stands on five occasions over one year. Spatial variability in epifaunal density was generally low, while temporal densities were highly variable through time. Spatial patterns of invertebrate abundance revealed few associations with habitat structure or water quality, apart from those associated with water depth, particularly when sampling had been preceded by fluctuating water levels. High temporal variability in assemblage structure of the epifauna reflects the high background environmental variation that occurs in this system. Copyright © 2007 John Wiley & Sons, Ltd.

Structure and Ordination of Epiphytic Invertebrate Communities of Four Coastal Wetlands in Green Bay, Lake Michigan

Epiphytic macroinvertebrate communities of four coastal wetlands of Green Bay, Lake Michigan were compared by taxonomic composition, feeding group composition, and environmental influences using Bray-Curtis ordination. Ordination scores from the most sheltered oligotrophic site, Portage Marsh, were distinct from the eutrophic, exposed sites located in middle and lower Green Bay— Seagull Bar, Little Tail Point, and Dead Horse Bay. Epiphyton chlorophyll a, phytoplankton chlorophyll a, and specific conductance strongly correlated to the ordination axes, indicating the trophic gradient within Green Bay was a primary environmental influence. The feeding group compositions at the sites were consistent with the type and abundance of food available. Portage Marsh is a scraper-shredder system, with macroinvertebrates feeding mainly on epiphyton and coarse particulate detritus. Dead Horse Bay and Little Tail Point are collector systems, sustained by phytoplankton and fine particulate organic matter. Seagull Bar is intermediate in trophic position along the ordination axes, but more closely resemble the latter two sites. The type and abundance of food resources available to these invertebrate communities are influenced by wave exposure, light attenuation, nutrient levels, and algae levels of the littoral and pelagial waters. Macroinvertebrate communities were sensitive to shifts in food resources, which generated shifts in trophic structure.

Importance of aquatic macrophyte for invertebrate diversity in large subtropical reservoir

The abundance and preferences of individual invertebrate populations (including zooplankton) closely associated with the substrates provided by aquatic plant structures and open-water areas of Lake Nasser were quantified in this study in order to gain understanding of the importance of submerged macrophyte for invertebrate diversity, and their relation to water properties. The following water parameters were measured: temperature, pH, dissolved oxygen (DO), total dissolved salts, electrical conductivity, turbidity, total suspended solids, carbonate, bicarbonate, nitrate, nitrite, phosphate, sulphate, silica, potassium, total hardness, calcium and magnesium. Five macrophyte species were recorded: Myriopyllum spicatum, Najas horrida, Potamogeton schweinfurthii, Potamogeton pectinatus and Vallisneria spiralis. In total 67 invertebrate species were recorded, comprising 39 Rotifera, 12 Cladocera, 4 Copepoda, 4 Insecta, 2 Protozoa, 2 Ostracoda and one species of Turbellaria, Tardigrada, Annelida and Nematoda. Thirty-seven species were exclusively epiphytic, 11 species were collectively planktonic and 19 species were found in both habitats. The greatest abundance of epiphytic invertebrates occurred in association with N. horrida– P. schweinfurthii community. The results indicated that total suspended solids (TSS), TH and NO 2 are the most influential water variables on the distribution of the aquatic macrophyte samples and their invertebrate communities. Also, the study indicates that water variables have a higher impact on the aquatic macrophytes than on the associated invertebrate populations. P, NO 3, K, Na, Mg, Cl and DO were the most influential water variables that dictate the distribution of invertebrate groups recorded in the open-water zone. Water temperature, electric conductivity, pH, NO 2, SO 4 −−, SiO 3 −, CO 3 −− and turbidity have a lesser influence of the distribution of the invertebrates recorded in this zone.