scholarly journals Bioerosion and fungal colonization of the invasive foraminiferan <i>Amphistegina lobifera</i> in a Mediterranean seagrass meadow

2021 ◽  
Vol 18 (8) ◽  
pp. 2777-2790
Author(s):  
Martin Vohník
Keyword(s):  
Benthic Communities ◽  
Mechanical Damage ◽  
Terrestrial Ecosystems ◽  
Vital Staining ◽  
Posidonia Oceanica ◽  
Fungal Colonization ◽  
Minor Role ◽  
Indigenous Species ◽  
Dark Septate Endophyte ◽  
Fungal Organisms

Abstract. Foraminiferans are diverse micro- to macroscopic protists abundant especially in (sub)tropical seas, often forming characteristic benthic communities known as “living sands”. Numerous species have migrated through the Suez Canal to the Mediterranean and one of them, i.e., Amphistegina lobifera, turned invasive, gradually outcompeting the indigenous species. At some places, A. lobifera creates thick seabed sediments, thus becoming an important environmental engineer. However, little is known about the turnover of its shells in the invaded ecosystems. Using vital staining, stereomicroscopy, scanning electron microscopy, and cultivation and DNA fingerprinting, I investigated the vital status, destruction/decomposition and mycobiota of A. lobifera in the rhizosphere of the dominant Mediterranean seagrass Posidonia oceanica in an underwater Maltese meadow (average 284 shells g−1, representing 28.5 % of dry substrate weight), in comparison with epiphytic specimens and P. oceanica roots. While 78 % of the epiphytes were alive, nearly all substrate specimens were dead. On average, 80 % of the epiphytes were intact compared to 21 % of the substrate specimens. Abiotic dissolution and mechanical damage played only a minor role, but some bioerosion was detected in 18 % and >70 % of the epiphytic and substrate specimens, respectively. Few bioerosion traces could be attributed to fungi, and the majority probably belonged to photoautotrophs. The seagrass roots displayed fungal colonization typical for this species and yielded 81 identified isolates, while the surface-sterilized substrate specimens surprisingly yielded no cultivable fungi compared to 16 other identified isolates obtained from the epiphytes. While the epiphytes' mycobiota was dominated by ascomycetous generalists also known from terrestrial ecosystems (alongside with, for example, a relative of the “rock-eating” extremophiles), the roots were dominated by the seagrass-specific dark septate endophyte Posidoniomyces atricolor and additionally contained a previously unreported lulworthioid mycobiont. In conclusion, at the investigated locality, dead A. lobifera shells seem to be regularly bioeroded by endolithic non-fungal organisms, which may counterbalance their accumulation in the seabed substrate.

scholarly journals Dead sands: bioerosion of alien foraminiferal shells in a Mediterranean seagrass meadow

2021 ◽  
Author(s):  
Martin Vohník
Keyword(s):  
Benthic Communities ◽  
Mechanical Damage ◽  
Terrestrial Ecosystems ◽  
Vital Staining ◽  
Posidonia Oceanica ◽  
Fungal Colonization ◽  
Minor Role ◽  
Indigenous Species ◽  
Dark Septate Endophyte ◽  
Fungal Organisms

Abstract. Foraminiferans are diverse macroscopic protists abundant in (sub-)tropical seas, often forming characteristic benthic communities known as living sands. Numerous species have migrated through the Suez Canal to the Mediterranean, some turning invasive and gradually outcompeting the indigenous species. The most expansive Amphistegina lobifera often creates thick seabed sediments, thus becoming an important environmental engineer. However, little is known about the turnover of its shells in the invaded ecosystems. Using vital staining, stereomicroscopy, scanning electron microscopy, cultivation and DNA fingerprinting, I investigated the vital status, destruction/decomposition and mycobiota of A. lobifera in the rhizosphere of the dominant Mediterranean seagrass Posidonia oceanica in an underwater Maltese meadow (average 284 shells/g, representing 28.5 % of dry substrate weight), in comparison with epiphytic specimens and P. oceanica roots. While 78 % of the epiphytes were alive, nearly all substrate specimens were dead. On average, 80 % of the epiphytes were intact, compared to 21% of the substrate specimens. Abiotic dissolution and mechanical damage played only a minor role, but some bioerosion was detected in 18 % and > 70 % of the epiphytic and substrate specimens, respectively. Few bioerosion traces could be attributed to fungi and the majority probably belonged to photoautotrophs. The seagrass roots displayed fungal colonization typical for this species and yielded 81 identified isolates, while the surface-sterilized substrate specimens surprisingly yielded no cultivable fungi, compared to other 16 identified isolates obtained from the epiphytes. While the epiphytes' mycobiota was dominated by ascomycetous generalists also known from terrestrial ecosystems (alongside with, e.g., a relative of the rock-eating extremophiles), the roots were dominated by the seagrass-specific dark septate endophyte Posidoniomyces atricolor and additionally contained a previously unreported lulworthioid mycobiont. In conclusion, dead A. lobifera shells seem to be regularly bioeroded by endolithic non-fungal organisms, which may counterbalance their accumulation in the seabed substrate.

scholarly journals Insect herbivory facilitates the establishment of an invasive plant pathogen

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Martin M. Gossner ◽  
Ludwig Beenken ◽  
Kirstin Arend ◽  
Dominik Begerow ◽  
Derek Peršoh
Keyword(s):  
Invasive Plant ◽  
Pathogenic Fungus ◽  
Feeding Activity ◽  
Insect Herbivory ◽  
Forest Health ◽  
Mechanical Damage ◽  
Pathogenic Fungi ◽  
Fungal Colonization ◽  
Feeding Damage ◽  
The Impact

AbstractPlants can be severely affected by insect herbivores and phytopathogenic fungi, but interactions between these plant antagonists are poorly understood. We analysed the impact of feeding damage by the abundant herbivore Orchestes fagi on infection rates of beech (Fagus sylvatica) leaves with Petrakia liobae, an invasive plant pathogenic fungus. The fungus was not detected in hibernating beetles, indicating that O. fagi does not serve as vector for P. liobae, at least not between growing seasons. Abundance of the fungus in beech leaves increased with feeding damage of the beetle and this relationship was stronger for sun-exposed than for shaded leaves. A laboratory experiment revealed sun-exposed leaves to have thicker cell walls and to be more resistant to pathogen infection than shaded leaves. Mechanical damage significantly increased frequency and size of necroses in the sun, but not in shade leaves. Our findings indicate that feeding damage of adult beetles provides entry ports for fungal colonization by removal of physical barriers and thus promotes infection success by pathogenic fungi. Feeding activity by larvae probably provides additional nutrient sources or eases access to substrates for the necrotrophic fungus. Our study exemplifies that invasive pathogens may benefit from herbivore activity, which may challenge forest health in light of climate change.

scholarly journals Variability in the settlement of non-indigenous species in benthic communities from an oceanic island

2018 ◽  
Vol 72 (1) ◽  
Author(s):  
Léa Riera ◽  
Patrício Ramalhosa ◽  
João Canning-Clode ◽  
Ignacio Gestoso
Keyword(s):  
Benthic Communities ◽  
Oceanic Island ◽  
Indigenous Species ◽  
Non Indigenous Species

scholarly journals Influence of Bio-Pollution on Ecosystem Processes: The Impact of Introduced Lake Trout on Streams, Predators, and Forests in Yellowstone National Park

2002 ◽  
Vol 26 ◽  
pp. 71-77
Author(s):  
Jamie Crait ◽  
Merav Ben-David ◽  
Bob Hall
Keyword(s):  
Nutrient Cycling ◽  
Yellowstone National Park ◽  
National Park ◽  
Lake Trout ◽  
Cutthroat Trout ◽  
Terrestrial Ecosystems ◽  
Spawning Migration ◽  
Indigenous Species ◽  
Yellowstone Lake ◽  
The Impact

Yellowstone National Park (YNP) is a treasured national resource and an important element of tourism and the recreational economy in Wyoming. Because of its unique geological features and abundant wildlife and fisheries, YNP is a tourist destination for millions of people annually. Although this national symbol is cherished for its pristine condition and has been protected from most human influence for over 100 years, human mediated invasions of non­ indigenous species, such as several species of plants and animals, including an exotic snail (Potamopyrgus antipodarum), may alter this ecosystem. Recently an unauthorized introduction of lake trout (Salvelinus namaycush) to Yellowstone Lake was documented. Recent investigation at the University of Wyoming, indicated that in-lake predation by lake trout on juvenile and sub-adult native Yellowstone cutthroat trout (Oncorhyncus clarki bouvieri) could negatively influence recruitment of cutthroat trout (Stapp and Hayward 2002). This may lead to significant reductions in numbers of spawning adult cutthroat if current management actions are ineffective, or if they are not continuously pursued (Stapp and Hayward 2002). While lake trout invasion in Yellowstone Lake will likely have detrimental effects on in-lake communities and processes, reductions in populations of native cutthroat trout can potentially impact other aquatic and terrestrial ecosystems outside of Yellowstone Lake. Cutthroat trout in Yellowstone Lake annually migrate into tributary streams and rivers to spawn (Varley and Gresswell 1988), with runs up to 60,000 trout per season into small streams such as Clear Creek (Gresswell and Varley 1988). This spawning migration may significantly affect in­ stream communities (cf. Power 1990) and alter nutrient cycling within tributary streams (Peterson et al. 1993) and in the adjacent riparian forests (Ben­David et al. 1998; Hilderbrand et al. 1999). Therefore, spawning cutthroat trout not only have trophic effects on their ecosystem but also act as "ecosystem engineers" (i.e., species that influence structure and function of ecosystems through non­ trophic processes) because of their role in transporting large amounts of nutrients between ecosystems (Jones et al. 1994). Reductions in spawning adult cutthroat trout will likely alter in­stream processes. In addition, for piscivorous (fish­eating) predators, a significant decline in the number of adult spawning cutthroat trout may reduce recruitment and survival, and it could threaten viability of predator populations. In this project we are investigating the role of cutthroat trout in structuring stream ecosystems, their importance to a representative fish-predator - the river otter (Lontra canadensis), and possible effectson terrestrial plants through nutrient transport by otters to latrine sites (Ben-David et al. 1998 Hilderbrand et al. 1999). We hypothesize that the spawning migration of cutthroat trout will result in transport of nutrients from lake to streams, and from streams to terrestrial forests, through the activity of piscivorous predators. Because nitrogen (N) limits production in area streams (J. L. Tank and R 0. Hall unpublished data) and terrestrial ecosystems (Nadelhoffer et al. 1995) we focus our investigation of nutrient cycling on this element. These observations will enable us to predict how streams, trout predators, and the terrestrial landscape will be affected following cutthroat trout decline.

scholarly journals Phenotypic plasticity mediates climate change responses among invasive and indigenous arthropods

2007 ◽  
Vol 274 (1625) ◽  
pp. 2531-2537 ◽  
Author(s):  
Steven L Chown ◽  
Sarette Slabber ◽  
Melodie A McGeoch ◽  
Charlene Janion ◽  
Hans Petter Leinaas
Keyword(s):  
Climate Change ◽  
Invasive Species ◽  
Phenotypic Plasticity ◽  
Global Change ◽  
Terrestrial Ecosystems ◽  
Indigenous Species ◽  
Potential Threat ◽  
Human Welfare ◽  
Change Type ◽  
Climate Change Responses

Synergies between global change and biological invasion have been identified as a major potential threat to global biodiversity and human welfare. The global change-type drought characteristic of many temperate terrestrial ecosystems is especially significant because it will apparently favour invasive over indigenous species, adding to the burden of conservation and compromising ecosystem service delivery. However, the nature of and mechanisms underlying this synergy remain poorly explored. Here we show that in a temperate terrestrial ecosystem, invasive and indigenous springtail species differ in the form of their phenotypic plasticity such that warmer conditions promote survival of desiccation in the invasive species and reduce it in the indigenous ones. These differences are consistent with significant declines in the densities of indigenous species and little change in those of invasive species in a manipulative field experiment that mimicked climate change trends. We suggest that it is not so much the extent of phenotypic plasticity that distinguishes climate change responses among these invasive and indigenous species, as the form that this plasticity takes. Nonetheless, this differential physiological response provides support for the idea that in temperate terrestrial systems experiencing global change-type drought, invasive species may well be at an advantage relative to their indigenous counterparts.

EFFECT OF SPILLS OF DISPERSED AND NON-DISPERSED OIL ON INTERTIDAL INFAUNAL COMMUNITY STRUCTURE

1983 ◽  
Vol 1983 (1) ◽  
pp. 457-463 ◽  
Author(s):  
E. S. Gilfillan ◽  
S. A. Hanson ◽  
D. Vallas ◽  
R. Gerber ◽  
D. S. Page ◽  
...  
Keyword(s):  
Community Structure ◽  
Adverse Effects ◽  
Intertidal Zone ◽  
Benthic Communities ◽  
Indigenous Species ◽  
Test Plot ◽  
Infaunal Community ◽  
Dispersed Oil ◽  
Measurable Amount ◽  
Upper Intertidal

ABSTRACT The effect of two nearshore discharges of Murban crude oil on community structure in intertidal benthic communities was studied. One discharge consisted of 250 gallons of Murban crude only. Following the discharge, no measurable amount of Murban crude could be found in sediments exposed to the cloud of dispersed oil. Significant amounts were found in the test plot exposed to untreated oil. In the area exposed to untreated oil, more oil was found in the upper intertidal zone than lower down. Effects on infaunal communities mirrored the analytical results. There was no evidence of adverse effects on infaunal community structure from exposure to dispersed oil. There is clear evidence that exposure to untreated oil did adversely affect community structure. Some indigenous species were reduced in number or eliminated; there were blooms of opportunistic polychaetes. The changes in community structure brought about by the untreated oil are consistent with results observed at real-world oil spill sites.

scholarly journals Disturbance, colonization and development of Antarctic benthic communities

2006 ◽  
Vol 362 (1477) ◽  
pp. 11-38 ◽  
Author(s):  
David K.A Barnes ◽  
Kathleen E Conlan
Keyword(s):  
Temperature Stress ◽  
Benthic Communities ◽  
Larval Abundance ◽  
Indigenous Species ◽  
Benthic Organisms ◽  
Community Recovery ◽  
Sea Floor ◽  
Wind Speeds ◽  
Non Indigenous Species ◽  
The Antarctic

A decade has yielded much progress in understanding polar disturbance and community recovery—mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales—ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what we know now that we did not a decade ago.

scholarly journals The importance of different spatial scales in determining structural and functional characteristics of deep-sea infauna communities

2013 ◽  
Vol 10 (7) ◽  
pp. 4547-4563 ◽  
Author(s):  
J. Ingels ◽  
A. Vanreusel
Keyword(s):  
Functional Diversity ◽  
Deep Sea ◽  
Spatial Ecology ◽  
Spatial Scales ◽  
Benthic Communities ◽  
Standing Stock ◽  
Terrestrial Ecosystems ◽  
Small Scale ◽  
Functional Characteristics ◽  
Sampling Locations

Abstract. The urge to understand spatial distributions of species and communities and their causative processes has continuously instigated the development and testing of conceptual models in spatial ecology. For the deep sea, there is evidence that structural and functional characteristics of benthic communities are regulated by a multitude of biotic and environmental processes that act in concert on different spatial scales, but the spatial patterns are poorly understood compared to those for terrestrial ecosystems. Deep-sea studies generally focus on very limited scale ranges, thereby impairing our understanding of which spatial scales and associated processes are most important in driving structural and functional diversity of communities. Here, we used an extensive integrated dataset of free-living nematodes from deep-sea sediments to unravel the importance of different spatial scales in determining benthic infauna communities. Multiple-factor multivariate permutational analyses were performed on different sets of community descriptors (structure, structural and functional diversity, standing stock). The different spatial scales investigated cover two margins in the northeast Atlantic, several submarine canyons/channel/slope areas, a bathymetrical range of 700–4300 m, different sampling locations at each station, and vertical sediment profiles. The results indicated that the most important spatial scale for structural and functional diversity and standing stock variability is the smallest one; infauna communities changed substantially more with differences between sediment depth layers than with differences associated to larger geographical or bathymetrical scales. Community structure differences were greatest between stations at both margins. Important regulating ecosystem processes and the scale on which they occur are discussed. The results imply that, if we are to improve our understanding of ecosystem patterns of deep-sea infauna and the relevant processes driving their structure, structural and functional diversity, and standing stock, we must pay particular attention to the small-scale heterogeneity or patchiness and the causative mechanisms acting on that scale.

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