Morpho-Functional Traits Reveal Differences in Size Fractionated Phytoplankton Communities but Do Not Significantly Affect Zooplankton Grazing

The recent emergence of approaches based on functional traits allows a more comprehensive evaluation of the role of functions and interactions within communities. As phytoplankton size and shape are the major determinants of its edibility to herbivores, alteration or loss of some morpho-functional phytoplankton traits should affect zooplankton grazing, fitness and population dynamics. Here, we investigated the response of altered phytoplankton morpho-functional trait distribution to grazing by zooplankton with contrasting food size preferences and feeding behaviors. To test this, we performed feeding trials in laboratory microcosms with size-fractionated freshwater phytoplankton (3 size classes, >30 µm; 5–30 µm and <5 µm) and two different consumer types: the cladoceran Daphnia longispina, (generalist unselective filter feeder) and the calanoid copepod Eudiaptomus sp. (selective feeder). We observed no significant changes in traits and composition between the controls and grazed phytoplankton communities. However, community composition and structure varied widely between the small and large size fractions, demonstrating the key role of size in structuring natural phytoplankton communities. Our findings also highlight the necessity to combine taxonomy and trait-based morpho-functional approaches when studying ecological dynamics in phytoplankton-zooplankton interactions.

Microbiological Characteristics and Heavy Metal Pollution of Crude Oil Contaminated Water Bodies in Port Harcourt Metropolis, Nigeria

Crude oil exploration has been beneficial to our economy but detrimental to our environment with the artisanal refineries further compounding the challenge. This research was aimed at investigating the microbiology and heavy metal pollution of three crude oil polluted rivers in Rivers State, Nigeria and effects on living organisms inhabiting that environment. This study was carried out in three locations in South-South Nigeria (Eagle Island, Iwofe and Chokocho rivers). A total of 64 water samples (upstream and downstream points) were collected using appropriate containers and sterile polyethene bags for 6 crab samples for a period of three months. Water and crab samples were analyzed for heavy metals using Atomic Absorption Spectrophotometric method while microbiological analysis involved isolation and enumeration of microbial populations of the water and crab samples as well as characterization and identification of the isolates using standard methods Results showed Total Heterotrophic bacteria (THB) ranged from 6.0 × 106 cfu/ml to 9.0 × 108cfu/ml for the downstream locations and 1.7 × 106cfu/ml to 3.5 × 107cfu/ml for the upstream locations. Total Heterotrophic Fungi (THF) ranged from 2.0 × 104cfu/ml to 1.1 × 105cfu/ml for downstream locations and 0.1 × 104cfu/ml to 4.0 × 104cfu/ml for upstream locations, Hydrocarbon Utilizing Bacteria (HUB) ranged from 0.8 × 103cfu/ml to 4.0 × 103cfu/ml in downstream locations and 2.0 × 103cfu/ml to 7.4 × 103cfu/ml in upstream locations, Hydrocarbon Utilizing Fungi (HUF) ranged from 1.0 × 103cfu/ml to 6.0 × 103cfu/ml for downstream locations and 5.0 × 102cfu/ml to 8.0 × 103cfu/ml for upstream locations. The bacteria identified biochemically included Serratia sp., Enterobacter sp. and Salmonella sp. for the crab samples and Bacillus sp. was dominant in the water samples (Bacillus subtilis, Bacillus cereus, Bacillus carboniphilus). The heavy metals (Fe, Ni, Zn, Cd, Cu, Mn, Cr and Pb) were below the DPR permissible limit but are likely to increase since the activities leading to pollution are still ongoing. The crab as a filter feeder, had higher concentration of heavy metals and microbial population and the location with the highest crude oil pollution (14.5mg/l) had the lowest THB (6.0 × 106cfu/ml) as physicochemical parameters like the amount of Dissolved Oxygen had been altered.

Assessing the utility of marine filter feeders for environmental DNA (eDNA) biodiversity monitoring

Aquatic environmental DNA (eDNA) surveys are transforming how we monitor marine ecosystems. The time-consuming pre-processing step of active filtration, however, remains a bottleneck. Hence, new approaches omitting active filtration are in great demand. One exciting prospect is to use the filtering power of invertebrates to collect eDNA. While proof-of-concept has been achieved, comparative studies between aquatic and filter feeder eDNA signals are lacking. Here, we investigated the differences among four eDNA sources (water; bivalves; sponges; and ethanol in which filter-feeding organisms were stored) along a vertical transect in Doubtful Sound, New Zealand using three metabarcoding primers (fish (16S); MiFish-E/U). While concurrent SCUBA diver observations validated eDNA results, laboratory trials corroborated in-field bivalve eDNA detection results. Combined, eDNA sources detected 59 vertebrates, while divers observed eight fish species. There were no significant differences in alpha and beta diversity between water and sponge eDNA and both sources were highly correlated. Vertebrate eDNA was detected in ethanol, although only a reduced number of species were detected. Bivalves failed to reliably detect eDNA in both field and mesocosm experiments. While additional research into filter feeder eDNA accumulation efficiency is essential, our results provide strong evidence for the potential of incorporating sponges into eDNA surveys.

The use of green mussel as bioindicator of heavy metal pollution in Indonesia: a review

Asian green mussel is a marine animal that is used as food by most Indonesians. The mussels are widely cultivated in tropical countries such as Indonesia, Malaysia, Thailand, and other Asian countries. The mussel, known as perna viridis, is marine biota that is a filter feeder in the waters. Therefore, the quality of its meat is greatly influenced by the quality of the sea in its habitat. It is a food that is quite popular with the community but can endanger public health due to the accumulation of heavy metals. This study used a literature review by collecting data related to heavy metal concentrations in green mussel tissue in Indonesia. The results showed that the mussels from several sampling locations still exceeded the maximum acceptable limits of lead (Pb), mercury (Hg), and cadmium (Cd) concentration according to the standards of the food and drug administration of the Republic of Indonesia. Consumption of green mussels can increase health risks if you frequently consume them from cultivating or catching locations that have been contaminated with heavy metals.

Intertidal Community Differences Between the Cook Strait and Wellington Harbour

<p>Wellington Harbour which lies near the southern tip of the North Island, New Zealand, exhibits a typical rocky intertidal shoreline with groups of species similar to those found on many temperate rocky coasts around the world. A short distance away, the Cook Strait displays a very different shoreline in community composition compared with Wellington Harbour, most notably a distinct lack of filter feeders. This thesis aims to examine how exactly the community composition is different between the two coasts at a species level and if there are any environmental factors that can explain the differing distributions. Here, a series of field and laboratory experiments aim to examine why certain filter feeders (mussels) are absent from the Cook Strait shore, yet so abundant in Wellington Harbour ... This work indicates that the Cook Strait coastline has lower filter feeder abundances and an overall different community composition than Wellington Harbour. The cause of these differences appears to be bottom up regulation through the lack of food availability (phytoplankton) during winter months in the Cook Strait. The high commercial value of coastal environments in both fisheries and tourism heightens the need to understand these habitats. Unravelling the complex relationships between the seasonal changes in the water column and onshore biota is important for conserving and protecting these essential ecosystems in New Zealand and temperate shores worldwide.</p>

Intertidal Community Differences Between the Cook Strait and Wellington Harbour

<p>Wellington Harbour which lies near the southern tip of the North Island, New Zealand, exhibits a typical rocky intertidal shoreline with groups of species similar to those found on many temperate rocky coasts around the world. A short distance away, the Cook Strait displays a very different shoreline in community composition compared with Wellington Harbour, most notably a distinct lack of filter feeders. This thesis aims to examine how exactly the community composition is different between the two coasts at a species level and if there are any environmental factors that can explain the differing distributions. Here, a series of field and laboratory experiments aim to examine why certain filter feeders (mussels) are absent from the Cook Strait shore, yet so abundant in Wellington Harbour ... This work indicates that the Cook Strait coastline has lower filter feeder abundances and an overall different community composition than Wellington Harbour. The cause of these differences appears to be bottom up regulation through the lack of food availability (phytoplankton) during winter months in the Cook Strait. The high commercial value of coastal environments in both fisheries and tourism heightens the need to understand these habitats. Unravelling the complex relationships between the seasonal changes in the water column and onshore biota is important for conserving and protecting these essential ecosystems in New Zealand and temperate shores worldwide.</p>

Seagrass Patch Complexity Affects Macroinfaunal Community Structure in Intertidal Areas: An In Situ Experiment Using Seagrass Mimics

Seagrasses, as key ecosystem engineers in coastal ecosystems, contribute to enhancing diversity in comparison with nearby bare areas. It has been proved mainly for epifauna, but data on infauna are still scarce. The present study addresses how seagrass structural complexity (i.e., canopy properties) affects the diversity of infaunal organisms inhabiting those meadows. Canopy attributes were achieved using seagrass mimics, which were used to construct in situ vegetation patches with two contrasting canopy properties (i.e., shoot density and morphology) resembling the two seagrass species thriving in the inner Cadiz Bay: Zostera noltei and Cymodocea nodosa. After three months, bare nearby areas, two mimicked seagrass patches (‘Zostera’ and ‘Cymodocea’), and the surrounding natural populations of Zostera noltei were sampled in a spatially explicit way. Shifts in organism diets were also determined using 15N and 13C analyses in available food sources and main infaunal organisms, mixing models, and niche metrics (standard ellipse area). Seagrass-mimicked habitats increased the species richness (two-fold), organism abundance (three to four times), and functional diversity compared with bare nearby areas. The clam Scrobicularia plana (deposit/filter feeder) and the worm Hediste diversicolor (omnivore) were dominant in all of the samples (> 85%) and showed an opposite spatial distribution in the reconstructed patches: whilst S. plana accumulated in the outer-edge parts of the meadow, H. diversicolor abounded in the center. Changes in the isotopic signature of both species depending on the treatment suggest that this faunal distribution was associated with a shift in the diet of the organisms. Based on our results, we concluded that facilitation processes (e.g., reduction in predation and in bioturbation pressures) and changes in food availability (quality and quantity) mediated by seagrass canopies were the main driving forces structuring this community in an intertidal muddy area of low diversity.

Microbial stowaways – waterbirds as dispersal vectors of aquatic pro- and microeukaryotic communities

Aim: Waterbirds are important dispersal vectors of multicellular organisms such as macrophytes, aquatic macroinvertebrates, and zooplankton. However, no study to date has focused on their potential role in dispersing aquatic microbial communities. Here, we carried out the first explicit study on passive transport (endozoochory) of prokaryotes and unicellular microeukaryotes by waterbirds based on a metagenomic approach. By directly comparing the dispersed set of organisms to the source pool of a natural metacommunity, we aimed for a realistic estimate of the overall importance of waterbird zoochory for natural microbial communities. Location: Seewinkel region of Austria and Hungary. Taxon: Prokaryotes and unicellular microeukaryotes. Methods: In 2017 and 2018, water samples from natural aquatic habitats along with fresh droppings of the dominant greylag goose (Anser anser) and four other waterbird species were collected in a well-delineated habitat network of temporary saline ponds (soda pans). Their prokaryotic and microeukaryotic communities were identified via 16S and 18S rRNA gene amplicon sequencing and compared across years and waterbird species. Results: We found that up to 40% of the dominant aquatic microbial OTUs were transported by A. anser. OTU richness in A. anser droppings was lower, but compositional variation was higher compared to the aquatic communities, probably resulting from stochastic pick-up of microbes from multiple aquatic habitats. We furthermore found that prokaryote species composition of bird droppings followed the interannual turnover in the aquatic communities. Finally, we found species-specific differences among different waterbird species. Among them, the planktivore filter-feeder northern shovelers (Anas clypeata) collected and dispersed a more species-rich subset of microeukaryotes than shorebirds or geese. Main conclusions: Overall, our study provides the first quantitative empirical evidence of endozoochory in natural microorganism communities. These results imply that waterbirds may be crucial in maintaining ecological connectivity between discrete aquatic habitats at the level of microbial communities. Keywords: aquatic microorganisms, bacteria, connectivity, dispersal, endozoochory, phytoplankton, protists, waterbirds

Field evidence for microplastic interactions in marine benthic invertebrates

Microplastics represent an important issue of concern for marine ecosystems worldwide, and closed seas, such as the Mediterranean, are among the most affected by this increasing threat. These pollutants accumulate in large quantities in benthic environments causing detrimental effects on diverse biocenoses. The main focus of this study is on the ‘polychaetes-microplastics’ interactions, particularly on two species of benthic polychaetes with different ecology and feeding strategies: the sessile and filter feeder Sabella spallanzanii (Gmelin, 1791) and the vagile carnivorous Hermodice carunculata (Pallas, 1766). Since not standardized protocols are proposed in literature to date, we compared efficiencies of diverse common procedures suitable for digesting organic matter of polychaetes. After the definition of an efficient digestion protocol for microplastics extraction for both polychaetes, our results showed high microplastics ingestion in both species. Microplastics were found in 42% of individuals of S. spallanzanii, with a mean of 1 (± 1.62) microplastics per individual, in almost all individuals of H. carunculata (93%), with a mean of 3.35 (± 2.60). These significant differences emerged between S. spallanzanii and H. carunculata, is probably due to the diverse feeding strategies. The susceptibility to this pollutant makes these species good bioindicators of the impact of microplastics on biota.