Interrelation between plankton and benthos in the littoral algal community of Lake Yunoko,Central Japan

To ascertain the floristic interaction between phytoplankton and benthos in the littoral, the composition of each community was investigated and the effect of the substrata on the benthic communities was also examined.The main component of the benthic algal population wasFragilaria pinnata followed byF. pinnata var.lancettula. Although the dominant species of the plankton in the upper layers were similar to those in the limnetic, and those immediately above the bottom contained species of benthic origin, the similarity index of C implied high similarity between these two plankton layers. This index was developed by Morishita (1959) to measure the degree of overlap of component species between two communities. The value of C distributes from 0 to 1. The closer the value approaches 1, the more the communities are similar.For the dominant species, a significant difference was observed between the phytoplankton and benthic communities and in addition, C values indicated low overall similarity in the composition of the communities. These results suggest that there is little interrelation between phytoplankton and benthos even in the shallow littoral zone.     

Middle gaspé limestones communities on the forillon Peninsula,Quebec, Canada (Siegenian,Lower Devonian)

Lower Devonian quiet-water marine benthic communities were examined to determine what parameters of community structure are maintained from locality to locality. The preserved elements of the communities are dominated by brachiopods. Each community has a characteristic taxonomic composition and diversity. From stratigraphically lowest to highest the communities include the newly proposed Dawsonelloides Community which has relatively low diversity, and is strongly dominated by a single species. The Beachia Community is less strongly dominated by a single species. The newly proposed Leptostrophia Community is very strongly dominated by a single species; less common species are rare or absent in the other communities. The Plicoplasia Community is slightly less diverse than the preceeding two communities, but unlike them has six species which dominate one or more collections and are commonly found in reduced abundance in the other collections. The gradual change in taxonomic composition and structure from one community to adjacent communities coupled with the similar structure of diversity and dominance within particular communities suggest that these characteristics are time-averaged and primary structural features of the communities.     

Patterns in the composition of the rotifer communities from high mountain lakes and ponds in Sierra Nevada (Spain)

On the basis of periodic collections of rotifers from 29 lakes and ponds over 2500 m above sea level in the Sierra Nevada (Southern Spain), patterns of species richness, distribution and community composition were evaluated. Results allow us to distinguish communities which fall into two major lake types. One is defined by the presence of typically planktonic species as well as lower specific richness whereas the other includes communities of mainly benthic and periphytic species. Both lake types seem to be related to small differences in their physical and chemical characteristics. These relationships and the influence of littoral vegetation are discussed.Research supported by CAICYT Project n° 3069/83     

Littoral zone fish communities of two Florida lakes and a comparison with Michigan lakes

Synopsis The abundance and habitat distribution of littoral zone fishes in two small southern Florida lakes were quantified by underwater censuses. The bluegill (Lepomis macrochirus) and large-mouth bass (Micropterus salmoides) accounted for 75–80% of community biomass in both lakes; important coexisting species were predominantly benthic feeders in Lake Sirena and planktivores in Lake Annie. All species were largely confined to areas of macrovegetation which extended to a depth of 4 m in Lake Annie but only to 1.2 m in Lake Sirena. The differences in community structure were related to differences in habitat and also variation in water levels and benthic production.A comparison of community composition with that of small Michigan lakes indicated that similar numbers of species coexist in the littoral zones, despite a three-fold difference in the size of regional species pools. The majority of families and about 50% of the species were common to lakes in both regions; in addition a number of ecological analogues were noted. A major difference was that the small inshore species were members of the Cyprinodontiformes in Florida and Cyprinidae in Michigan. Together the largemouth bass and bluegill comprise similar community proportions in the two regions as do other major feeding groups. Lakes in the two regions that are similar in amount and distribution of vegetation exhibit greater similarity in fish communities than those within regions that differ in littoral vegetation.     

The benthic macroinvertebrate community in a coastal sand dune lake relative to habitat and changing lake levels

The benthic macroinvertebrate community (BMI) in a freshwater coastal dune lake without a surface outlet was investigated in May and October, 1986. Fifty-three invertebrate taxa were identified from Carter Lake, including three euryhaline crustacean species (Corophium spinicorne, Gnorimosphaeroma oregonensis lutea, and Acanthomysis awatchensis). Corophium spinicorne dominated the BMI communities of the littoral zones and sphaeriid clams dominated the deepwater community.The lake level dropped about 2.5 m between April and October. Based upon this decline, the lake bottom was divided into four major habitats: a sandy temporarily submerged littoral zone (A); a sandy submerged littoral zone (B); and mid-depth zone of mixed mud and sand and the macrophyte, Nitella (C); and a deep zone (D) with soft mud. The average density of BMI was highest in the littoral zones (A and B) in May and in zone B in October (zone A was dry). The lowest density occurred in zone D. In May, BMI biomass was highest in the littoral zones, but the biomass was highest in the mid-depth zone in October. The mid-depth zone in October. The mid-depth zone had the most diverse community.The two most abundant species in the temporarily submerged area, Corophium spinicorne and Juga plicifera, were found in greater numbers deeper in the lake after the water level dropped, suggesting migration by these species in response to changing water levels.     

Assessment of Littoral Benthic Invertebrate Communities at the Land–Water Interface in Lakes Recovering from Severe Acid- and Metal-Damage

Benthic invertebrate communities within confluence sites, or areas of sediment deposition, are shaped by the input of catchment products including coarse woody debris, organic and inorganic particulates, and contaminants, but these sites also appear to be potential “hotspots” where recolonization of severely damaged ecosystems begins. Two species of leaf packs and a sweep netting technique were used to assess benthic invertebrate communities across a gradient of 14 confluence sites in 3 recovering lakes near the copper and nickel smelters in Sudbury, Canada. Environmental variables including delta habitat composition, delta area and length, and composition of deposited materials were used to detect spatial patterns in littoral benthic invertebrate communities. Benthic invertebrate community relationships with water chemistry were also assessed. Partial redundancy analysis (pRDA) showed that all sampling methods detected similar gradients of increasing invertebrate community richness and diversity as area and length of the sediment delta and the surface organic matter abundance increased. Two-way nested ANOVAs showed significant differences (p < .05) in taxa richness and diversity metrics among sites. Of the three methods, the benthic invertebrate community measurements from the birch leaf packs provided the strongest correlations with measures of organic matter inputs or habitat characteristics of the confluence zones. These correlations suggest that tree planting in riparian areas, or organic matter or macrophyte additions to littoral zones, may enhance littoral benthic invertebrate richness and diversity in acid and metal damaged lakes.     

Spatial scale and benthic community organisation in the littoral zones of large oligotrophic lakes: potential for cross-scale interactions

1. We studied the spatial organisation of littoral, benthic invertebrate communities in two large oligotrophic lakes with very extensive heterogeneous littoral zones, and report that littoral communities show significant variation in their structure at multiple spatial scales. 2. At coarser scales, littoral zone topography, riparian inputs and exposure may be important drivers of community spatial structure. At finer scales, the composition of substrates, particularly macrophytes and inorganic sediments, may be drivers of community spatial structure. 3. The effects of substrates on community spatial patterns were non‐additive across scales; community‐habitat correspondence became very noisy when we attempted to extrapolate results throughout the littoral. We present some evidence to suggest that this non‐additivity is because of the interaction among structuring processes that operate at different scales.     

Multiple scales and the relationship between density and spatial aggregation in littoral zone communities

Understanding the constraints on community composition at multiple spatial scales is an immense challenge to community and ecosystem ecologists. As community composition is basically the composite result of species’ spatial patterning, studying this spatial patterning across scales may yield clues as to which scales of environmental heterogeneity influence communities. The now widely documented positive interspecific relationship between ‘regional’ range and mean ‘local’ abundance has become a generalisation describing the spatial patterning of species at coarse scales. We address some of the shortcomings of this generalisation, as well as examine the cross‐scale spatial patterning (aggregation and density levels) of littoral‐benthic invertebrates in very large lakes. Specifically, we (a) determine whether the positive range‐abundance relationship can be reinterpreted in terms of the actual spatial structure of species distributions, (b) examine the relationship between aggregation and density across different spatial scales, and (c) determine whether the spatial patterning of species (e.g. low density/aggregated distribution) is constant across scales, that is, whether our interpretation of a species spatial pattern is dependent on the scale at which we choose to observe the system. Spatial aggregation of littoral invertebrates was generally a negative function of mean density across all spatial scales and seasons (autumn and spring). This relationship may underlie positive range‐abundance relationships. Species that were uncommon and highly aggregated at coarse spatial scales can be abundant and approach random distributions at finer spatial scales. Also, the change in spatial aggregation of closely related taxa across spatial scales was idiosyncratic. The idiosyncratic cross‐scale spatial patterning of species implies that multiple scales of environmental heterogeneity may influence the assembly of littoral communities. Due to the multi‐scale, species‐specific spatial patterning of invertebrates, littoral zone communities form a complex spatial mosaic, and a ‘spatially explicit’ approach will be required by limnologists in order to link littoral‐benthic community patterns with ecosystem processes in large oligotrophic lakes.     

Development of filamentous green algae in the benthic algal community in a littoral sand-beach zone of Lake Biwa

Temporal changes of biomass and dominant species in benthic algal communities were investigated in a littoral sand-beach zone in the north basin of Lake Biwa from December 1999 to September 2000. Chlorophyll-a amounts of benthic algal communities per unit area of the sandy sediments rapidly increased from late April to June. Increases in biomass of the benthic algal communities are considered to result from the propagation of filamentous green algae Oedogonium sp. and Spirogyra sp. The cell numbers of filamentous green algae and chlorophyll-a amounts of benthic algal communities at depths of 30 and 50cm at a station protected by a breakwater in May were significantly higher than those of a station exposed directly to wave activity. Thus, the biomass accumulation of the benthic algal communities seems to be regulated strongly by wave disturbance. The development of filamentous green algae may contribute to the increase in biomass of the benthic algal community and to the changes in seasonal patterns of biomass in the sand-beach zone of Lake Biwa. We consider that the development of the filamentous green algal community in the littoral zone of Lake Biwa is the result of eutrophication.     

Seasonal variability of macrozoobenthos in a lagoon having a periodic connection with the sea (Ptich’e Lake,southern Sakhalin)

The seasonal variability of the macrozoobenthos in a saline lagoon characterized by the absence of a permanent connection with the sea is described according to the results of a survey in Ptich’e Lake (southern Sakhalin) in 2012–2013. Changes in the species composition, abundance, and biomass of the macrozoobenthos have been revealed. Features of the formation of species complexes, benthic communities, and trophic groups are shown. Causes of the phenomena described are discussed.     

Trophic structure of shallow-water benthic communities in the sub-Antarctic Strait of Magellan

Trophic structure is among the most fundamental characteristics of an ecosystem since it is a useful way to determine the main energy flow at the ecosystem level. In the Magellan Strait, the local spatial heterogeneity at the shallow-waters ecosystems may have a great variety of potential food sources; however, knowledge about their biological communities and their structure is still unclear. We examined the trophic structure of shallow-water-mixed bottom communities at two sites in the sub-Antarctic Magellan Strait based on carbon (δ ¹³C) and nitrogen (δ ¹⁵N) stable isotope ratios. The benthic communities were composed of 46 species from 20 major taxa at Bahía Laredo (BL) and 55 species from 18 major taxa at Punta Santa Ana (PSA). Benthic macroalgae and organic matter associated with sediment are the major primary food sources at both sites. Although both sites are quite similar in their food sources and in their vertical trophic structure (≥three trophic levels), the food web structure varied distinctly. Functionally, predators and grazers dominated both communities, but top predators were shorebirds, carnivore anemones and predatory nemerteans at BL, and sea stars, shorebirds, crabs and fishes at PSA. The distinct differences in the trophic structure at BL and PSA highlight the important variability of δ ¹⁵N at the base of the benthic food web, the role of local environmental conditions and community dynamics in structuring shallow-water communities.

     

Intertidal rocky shore biotopes of the Azores: a quantitative approach

Rocky littoral communities of the Azores are dominated by macroalgae where turf formations represent the main life form as on many subtropical and tropical shores. The present study aimed at describing and classifying benthic intertidal biotopes of the Azores using clear quantification and data analysis methodologies to be used in similar studies for spatial and/or temporal comparison. This numerical approach intends to have management and conservation applicability. Thirty study locations along the coast of São Miguel island were characterised by substratum type (cobbles, boulders or bedrock – different stability levels) and exposure to wave action (high, medium or low exposure), from June to August 2002. Algae, sessile and sedentary invertebrates were recorded along transects, and the more conspicuous taxa quantified. Community structure is mainly shaped by substratum stability – unstable cobble communities are separate from those of more stable boulders and bedrock. Boulders present an intermediate community composition between cobbles and bedrock. Exposure to wave action induces smaller variation in community composition. Sixteen biotopes have been recognised. Ultimately the present paper provides an objective set of biotope definition tools for a broad public whose interest focuses on spatial and temporal comparison of coastal communities and associated habitats.     

Peculiarities of the Structure of and Trends in the Macrobenthos Community of the Ermolinskaya Bay Lagoon Ecosystem,Kandalaksha Bay,White Sea

The species composition and spatial and trophic structures of the macrobenthos communities of the Ermolinskaya Bay were studied, and the main changes that had occurred since previous explorations (the 1960s) were analyzed. The most significant changes in the spatial structure of the macrobenthos community (species diversity, population density and biomass, and similarities of the species’ distribution) were observed with regard to the sea level zone: the most pronounced at the upper littoral, followed by the middle littoral, lower littoral, and sublittoral. The longitudinal gradient of the community structure (from the innermost area seaward) was pronounced less strongly. Altogether, four macrobenthos communities can be identified in Ermolinskaya Bay; they differ in species composition, diversity, population density and biomass, and trophic structure: (1) community of the upper littoral with the dominance of collecting deposit feeders, Hydrobia ulvae, and scrapers, Littorina saxatilis; (2) community of the middle littoral with the prevalence of deposit feeders, Hydrobia ulvae and Macoma balthica, seston feeders, Mya arenaria, and, to a lesser extent, Mytilus edulis; (3) community of the lower littoral with the domination of the filtering organisms, Mytilus edulis, to a lesser extent collecting deposit feeders, Hydrobia ulvae and Macoma balthica, and scrapers, Littorina littorea; and (4) community of the sublittoral, where the leading positions belong to the group of collecting deposit feeders, Macoma balthica, to a lesser extent also Hydrobia ulvae (in the innermost area) and Capitella capitata, Arenicola marina (in the marine part of the bay). The gradual siltation of the bay and the reduction of its connection to the sea have led to the development of a littoral complex of species in the sublittoral, whereas the species typical at the sublittoral in the 1960s are now mainly found at the outlet of the bay.     

Do introduced crayfish affect benthic fish in stony littoral habitats of large boreal lakes?

Invasive crayfish are spreading rapidly across Europe, where they are replacing the native crayfish species and impacting negatively on some other biota. Freshwater crayfish and many benthic fishes share similar habitat and food requirements and hence potentially compete for resources. In this study, we investigated impacts of the introduced signal crayfish (Pacifastacus leniusculus) on fish in stony littoral habitats of two large boreal lakes. We compared the littoral fish community composition and the densities of two common benthic fish species between sites with and without crayfish. To evaluate whether signal crayfish share the same food resources as benthic littoral fish or change their feeding habits, we used mixing models and trophic niche estimates based on analyses of stable isotopes of carbon and nitrogen. Both the community composition of littoral fish and the densities of benthic fish species were similar at sites with and without signal crayfish. Even though stable isotope signatures indicated strong dietary overlap between crayfish and benthic fish, the use of food sources and trophic niche widths of fish were not noticeably different between crayfish sites and non-crayfish sites. Our results suggest that, at current densities, the non-native signal crayfish does not have significant impacts on benthic fish in the stony littoral habitats of large boreal lakes.     

Collapse of the native ruffe (<Emphasis Type="Italic">Gymnocephalus cernua</Emphasis>) population in the Biesbosch lakes (the Netherlands) owing to round goby (<Emphasis Type="Italic">Neogobius melanostomus</Emphasis>) invasion

We investigated the change in benthic fish communities in three artificial lakes of the Biesbosch area in the Netherlands between two time periods: before and after the invasion of round goby (Neogobius melanostomus). Native ruffe (Gymnocephalus cernua), the dominant species in benthic gillnet and littoral beach seining catches before the invasion, almost completely disappeared in all lakes only 2 years after the invasion. We found a significant increase in 0 + perch (Perca fluviatilis) and, in some lakes, pikeperch (Sander lucioperca) abundance in gillnet catches after invasion. In the post-invasion period, the 0 + fish community was dominated by perch, and the older fish community was dominated by round goby. The species richness of 0 + fish increased in the post-invasion period owing to the invasion of gobiids. However, it did not change for older fish between periods. Our results clearly show that, owing to a similar benthic lifestyle and high niche overlap, ruffe was the only species negatively influenced by the round goby invasion. The competitive superiority of round goby over ruffe is so strong that the once-dominant species of the overall benthic fish community collapsed after only a few years of coexistence.     

In situ experiments on the effects of increased sediment loads on littoral rocky shore communities in Lake Tanganyika, East Africa

1. Two in situ experiments investigated the responses to artificially increased sediment loads of the gastropod and fish communities, and of the whole benthos, of the rocky shores of Lake Tanganyika. Sediments were emptied once onto randomly selected quadrats using SCUBA, with control quadrats receiving no addition of sediment. Quadrats were monitored up to 6 months after sediment addition. 2. While the abundance of Lavigeria grandis (Mollusca; Gastropoda) was reduced greatly by the addition of sediment, low abundance and biomass of the whole gastropod community on sediment‐impacted quadrats 6 months after sediment addition suggests more general impacts of inundation in the longer term. 3. Benthic invertebrate communities inundated by sediment had significantly fewer individuals and numbers of taxa than control communities. No significant community recovery was recorded on sediment‐impacted quadrats within the timescale of the experiment. A short‐term period of high turbidity brought about by the emptying of sediments onto sediment‐impacted quadrats also caused severe decreases in benthic invertebrate abundance on controls 10 days after sediment addition. This suggests that even short‐term pulses of sediment may have significant detrimental effects on littoral communities. 4. Although significant impacts of sediment on fish community dynamics were found, and a significant reduction in the number of benthic algivorous species was recorded immediately after sediment addition, littoral fish communities showed strong resistance overall to the addition of sediments. This apparent resistance, however, may be a consequence of the small scale at which the experiment took place. Littoral fish communities were also shown to be more dynamic than indicated previously.     

Effects of UV radiation on the structure of Arctic macrobenthic communities

At present, information on the effects of ultraviolet radiation (UVR) on structure and diversity of polar, in particular Arctic, benthic communities is scarce. It is unclear whether and to what extent communities of different successional age are susceptible to UVR and whether UVR effects known to be detrimental at the species level can be buffered at the community level. In a subtidal field study on Spitsbergen (Norwegian Arctic), we investigated the potential effect of distinct UVR regimes on macrobenthic communities of different successional ages, grown on ceramic tiles. Total taxon cover, taxon composition, evenness, and richness were assessed after experimental exposure of 4 and 8 weeks. Overall, 17 algal and invertebrate taxa were encountered in the study and diatoms dominated the communities regardless of successional age or radiation treatment. UVR effects were dependent on both exposure time and community age. We did not find overall detrimental UVB effects. In contrast, abundance of several species increased in UVR-exposed communities. Especially, UVA seemed to have a beneficial effect in that several green and brown algal taxa increased in abundance (e.g. Ulothrix flacca, Chlorophyta, and Desmarestia sp., Phaeophyceae). In general, UVR effects depended on species composition and thus on successional age of communities, with later successional communities likely to be able to buffer and alleviate possible negative effects of UVR at species level. Overall, the presented study provides a first insight into the complex role UVR plays in structuring Arctic epibenthic communities.     

Fishing-induced changes in predation pressure by perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis>) regulate littoral benthic macroinvertebrate biomass,density, and community structure

We aimed to study whether the varying changes in predation pressure by perch (Perca fluviatilis) reflect the biomass, density, and community structure of the benthic macroinvertebrates. Prey preference is size-dependent, and overall predation pressure is density dependent, and thus the size structure of the P. fluviatilis population should affect the structure of the macroinvertebrate community, and the population density of P. fluviatilis should reflect the overall density of benthic macroinvertebrates. We sampled the littoral benthic community in a boreal lake that had been divided into two parts that were subjected to two different fishing procedures during 2007–2012 period and analyzed the macroinvertebrate diet of fish. The benthic macroinvertebrate community reflected the predation pressure. Total macroinvertebrate biomass increased during the study period in the lake division with a non-size-selective fishing procedure (NSF), i.e., all invertivorous perch size-classes targeted, but decreased in the section with negatively size-selective fishing procedure (SSF), i.e., large invertivorous individuals ≥ 16 cm were not targeted. This difference was a result of the increase in large-sized species, such as Odonata, for the NSF procedure and decrease in the SSF procedure. In contrast to total biomass, total macroinvertebrate density did not show a response to predator size structure but rather total macroinvertebrate density decreased with increasing fish density. The study demonstrates the effect of predation pressure of P. fluviatilis on benthic communities, thus highlighting the keystone predator role of the species in boreal lakes and gives more insight on the multiple effects of fish predation on littoral benthic communities.     

The role of settlement in structuring a hard-substratum community in the deep sea

Larval settlement can play an important role in the structure of benthic communities in shallow-water habitats. Experimental studies of settlement and colonization in the deep sea, however, are few, and have concentrated exclusively on sedimentary habitats. Results are presented here from an in situ study designed to determine whether larval settlement patterns on a common, deep-sea hard substratum (manganese nodules) determine the subsequent structure of the epifaunal community. In a 7-wk deployment at a depth of 1240 m, settlement onto manganese nodules resting on the sediment in a relatively “low-flow” environment was significantly greater than onto nodules suspended in a “higher-flow” regime. After 2 yr, this difference in total number of individuals was no longer significant, but a new pattern in community composition emerged, which correlated to the presumed supply of paniculate food. Suspension-feeders dominated the elevated nodules (correlating to higher horizontal participate fluxes) and deposit-feeders dominated the nodules sitting on the sediment (correlating to higher particulate deposition). The faunal settlement patterns observed after 7 wk, therefore, appear to be altered by adult feeding requirements of the component species.     

Seasonal variation in benthic invertebrate recolonization of small-scale disturbances in a subtropical Florida lake

Approximately 11.5% of the littoral zone of a hypereutrophic Florida lake is disturbed by the construction of spawning beds by the cichlid fish, Sarotherodon aurea, during a single spawning season. Simulations of these beds were created during three seasons of the year to test for variation in recolonization rates and patterns in the benthic macroinvertebrate community.The seasonal variation in densities of benthic invertebrate populations suggests a direct relationship between reproductive activity and recolonization rate. Recolonization rates of the numerically dominant species, Polypedilum halterale (Diptera: Chironomidae), were much more rapid in the spring and summer than in the winter. In contrast, Hyalella azteca and Glyptotendipes paripes attained peak population densities during the winter season when Polypedilum was present in low densities. These organisms invaded the disturbed area in unusually high abundances and later declined to background levels. The final result was a winter population with densities comparable to the control (undisturbed) area, but the species composition was different.Similarity between disturbed and control communities during the winter season only reached 67% a month after disturbance, while communities during the warmer months attained nearly 90% similarity in less than 15 days. This lack of similarity during the winter indicates that disturbance, at the appropriate time, may play a role in community organization.