Detrital Subsidies in the Diet of Mytilus edulis; Macroalgal Detritus Likely Supplements Essential Fatty Acids

Detritus is a frequent, poorly defined, component of bivalve growth and carrying capacity models. The purpose of this study was to determine the proportional contributions of detrital material derived from primary producers (phytoplankton, macroalgae, Spartina alterniflora, and terrestrial leaf litter) to particulate organic matter (POM) and blue mussel’s (Mytilus edulis) diet within a temperate bay (Saco Bay, ME, United States). We assessed which detrital sources, if any, warranted incorporation into modeling efforts. Stable isotopes (δ13C and δ15N) and fatty acid biomarkers (FA) of mussels, size fractionated (<100 μm) POM, and primary producer endmembers (phytoplankton, Saccharina latissima, Ascophyllum nodosum, Chondrus crispus, Spartina alterniflora and leaf litter) collected between 2016 and 2017 were used to estimate endmember contributions to POM and mussel diets. Based on FAs dinoflagellates were the most abundant phytoplankton in Saco Bay, even during the fall diatom bloom. Diatoms within the bay were primarily centric, but pennate diatoms were at times present in the water column (e.g., in September). Following abundances of dinoflagellates, and centric and pennate diatoms, 22:6ω3 (DHA) was the most abundant essential FA (8.6 ± 0.1% total FAs), followed by 20:5ω3 (EPA: 7.0 ± 0.1%) and 20:4ω6 (ARA: 0.3 ± 0.1%). On average, phytoplankton derived organic matter contributed 22.1 ± 0.3% of the total POM in the bay. The concentration of non-fresh phytoplankton organic matter, or remaining organic matter (REMORG), was positively correlated with all endmember biomarkers. However, the proportion (%) of vascular plant, macroalgal, and detrital FAs was negatively correlated with the concentration of REMORG. This finding suggests in periods of low productivity, vascular plant and macroalgal detritus are proportionally more important contributors to POM. Mussels were broad spectrum omnivores, consuming phytoplankton, zooplankton, and detrital material. Detrital contributions to mussel diets were important (minimum of 16% of diet). Although small, macroalgae’s dietary contribution (8%) to M. edulis may be important. Macroalgal detritus contained essential FAs (20:5ω3 and 20:4ω6) that could supplement mussel diets, as M. edulis in Saco Bay were likely limited by 20:5ω3. Consideration of how macroalgal detritus affects the availability of essential FAs in POM may be useful to incorporate into aquaculture site selection.

Microalgae Diversities in Different Depths of Sendang Biru Beach, Malang East Java

Sendang Biru beach is a one of the coastal area located in Sumbermanjing Wetan, Malang, East Java-Indonesia. As a sea tourism, there are another residents activities such as fishing, fish landing and auction in Malang. That activities can caused pollution on the Sendang Biru aquatic environment. The research aim were to describe the water quality of Sendang Biru aquatic environment based on phytoplankton diversity. This research used several data collection techniques, that were microalgae sampling technique and measurement of physical and chemical water quality. Phytoplankton found in Sendang Biru Beach consists of 47 genus that are genus from seven divisions, Bacillariophyta, Chlorophyta, Cyanophyta, Euglenophyta, Dinophyta, Chrysophyta and Charophyta. The most abundant phytoplankton while having the Indeks Nilai Penting (INP) at the edge zone is the genus Oscillatoria sp. (the abundance is 4368000 Ind/L and INP 26,288). In the central and inner zones are both dominated by Coscinodiscus sp. (The abundance of center zone 4992000 Ind/L and INP 30,499; the abundance of inside zone is 9464000 Ind/L and INP 40,773). The level of diversity of phytoplankton in the three area of Sendang Biru beach are 2,297 in the edge zone; 2,37 in the central zone, and 1,8 in the inner zone. The pollution status of Sendang Biru beach can be classified as polluted moderately based on diversity index value on three different zone in the Sendang Biru Beach.

Dynamics of a Heterotrophic Dinoflagellate, Protoperidinium divergens, in the South-Eastern Coastal Waters of the Bay of Bengal

This research is the first attempt to present temporal distribution of heterotrophic dinoflagellate Protoperidinium divergens and their relationship with diatom and environmental factors in the Maheshkhali channel, south-east coast of the Bay of Bengal, Bangladesh. The initiation of higher abundances of P. divergens were observed in October and reached its peak in November when diatoms were the most abundant phytoplankton. Protoperidinium divergens preferred comparatively low temperature from 20-22°C and high concentration of phosphate-phosphorus from 31-37 µM. It had insignificant relationship with nitrate-nitrogen. Lower abundances of P. divergens were observed during pre-monsoon and monsoon due to lower abundances of diatom and higher water temperature (>23°C). Protoperidinium divergens, therefore, were mainly controlled by the availability of diatom abundance at comparatively lower temperature and higher concentration of phosphate-phosphorus. This research is important to estimate the potential trophic impact of P. divergens in the Maheshkhali channel.

Turbulence induces clustering and segregation of non-motile, buoyancy-regulating phytoplankton

Turbulence plays a major role in shaping marine community structure as it affects organism dispersal and guides fundamental ecological interactions. Below oceanographic mesoscale dynamics, turbulence also impinges on subtle physical–biological coupling at the single cell level, setting a sea of chemical gradients and determining microbial interactions with profound effects on scales much larger than the organisms themselves. It has been only recently that we have started to disentangle details of this coupling for swimming microorganisms. However, for non-motile species, which comprise some of the most abundant phytoplankton groups on Earth, a similar level of mechanistic understanding is still missing. Here, we explore by means of extensive numerical simulations the interplay between buoyancy regulation in non-motile phytoplankton and cellular responses to turbulent mechanical cues. Using a minimal mechano-response model, we show how such a mechanism would contribute to spatial heterogeneity and affect vertical fluxes and trigger community segregation.

Ecological Approach of Plankton Responses to Water Quality Variables of a Tropical River, South-Eastern Nigeria: A Bio-indicator-based Community Assessment of Idundu River

In the present study, the water quality variables of the Idundu River were assessed by evaluating the Plankton community. Three sampling stations: Station 1 (minimal fishing), station 2 (artisanal fishing area/ cluster of human settlements) and station 3 (fisheries landing area, dredging) representing regions along the stretch of the watershed with considerable economic importance and anthropogenic activity, were selected within the period of six (6) months. The study determines plankton distribution, diversity and some water quality variables of Idundu River, and how they influence plankton abundance. The results of this study reveal that water quality variables (mean ± SD) of the River were pH (6.526 ± 0.104), surface water temperature (26.224 ± 0.106˚C), dissolved oxygen (1.474 ± 0.135 mg/l), nitrate (0.026 ± 0.001 mg/l) and phosphate (0.015 ± 0.000 mg/l). All the water quality variables assessed were within the acceptable range. A total of 23 phytoplankton species belonging to five families, totalling a numerical abundance of 368 individuals/L were observed. Bacillariophyceae was the most abundant phytoplankton family (63.81%), followed by Chlorophyceae (17.41%), Dinophyceae (7.87%), Cryptophyceae (9.77%), and the least abundant was Zygnemophyceae accounting for (1.08%). A total of 20 zooplankton species belonging to five phyla, totalling a numerical abundance of 140 individuals/L were observed. Rotifera was the most abundant zooplankton phylum (35.69%), Arthropoda (30.62%), Ciliophora (17.79%) and Annelida (12.15%); the least abundant was Nemata (2.85%). Principal component analysis (PCA) for plankton organisms showed that phytoplankton were more homogenously distributed than zooplankton during the study period. Shannon Wiener and Margalef’s diversity index showed that the River is in a healthy condition and the equitability level was high across all the stations, indicating even plankton distribution.

A Parasitic Arsenic Cycle That Shuttles Energy from Phytoplankton to Heterotrophic Bacterioplankton

ABSTRACTIn many regions of the world oceans, phytoplankton face the problem of discriminating between phosphate, an essential nutrient, and arsenate, a toxic analogue. Many phytoplankton, including the most abundant phytoplankton group known,Prochlorococcus, detoxify arsenate (AsV) by reduction to arsenite (AsIII), followed by methylation and excretion of the methylated arsenic products. We synthesized [14C]dimethyl arsenate (DMA) and used it to show that culturedPelagibacterstrain HTCC7211 (SAR11) cells oxidize the methyl group carbons of DMA, producing14CO2and ATP. We measured [14C]DMA oxidation rates in the P-depleted surface waters of the Sargasso Sea, a subtropical ocean gyre. [14C]DMA was oxidized to14CO2by Sargasso Sea plankton communities at a rate that would cause turnover of the estimated DMA standing stock every 8.1 days. SAR11 strain HTCC7211, which was isolated from the Sargasso Sea, has a pair of arsenate resistance genes and was resistant to arsenate, showing no growth inhibition at As/P ratios of >65:1. Across the global oceans, there was a strong inverse relationship between the frequency of the arsenate reductase (LMWPc_ArsC) inPelagibactergenomes and phosphate concentrations. We propose that the demethylation of methylated arsenic compounds byPelagibacterand possibly other bacterioplankton, coupled with arsenate resistance, results in the transfer of energy from phytoplankton to bacteria. We dub this a parasitic cycle because the release of arsenate byPelagibacterin principle creates a positive-feedback loop that forces phytoplankton to continually regenerate arsenate detoxification products, producing a flow of energy to P-limited ocean regions.IMPORTANCEIn vast, warm regions of the oceans, phytoplankton face the problem of arsenic poisoning. Arsenate is toxic because it is chemically similar to phosphate, a scarce nutrient that phytoplankton cells need for growth. Many phytoplankton, including the commonest phytoplankton type in warm oceans,Prochlorococcus, detoxify arsenate by adding methyl groups. Here we show that the most abundant non-photosynthetic plankton in the oceans, SAR11 bacteria, remove the methyl groups, releasing poisonous forms of arsenic back into the water. We postulate that the methylation and demethylation of arsenic compounds creates a cycle in which the phytoplankton can never get ahead and must continually transfer energy to the SAR11 bacteria. We dub this a parasitic process and suggest that it might help explain why SAR11 bacteria are so successful, surpassing all other plankton in their numbers. Field experiments were done in the Sargasso Sea, a subtropical ocean gyre that is sometimes called an ocean desert because, throughout much of the year, there is not enough phosphorous in the water to support large blooms of phytoplankton. Ocean deserts are expanding as the oceans absorb heat and grow warmer.

Dynamics and interactions of highly resolved marine plankton via automated high frequency sampling

Short time-scale observations are valuable for understanding microbial ecological processes. We assessed dynamics in relative abundance and potential activities by sequencing the small sub-unit ribosomal RNA gene (rRNA gene) and rRNA molecules (rRNA) ofBacteria,Archaea, andEukaryotaonce to twice-daily between March 2014 and May 2014 from the surface ocean off Catalina Island, California. TypicallyOstreococcus, Braarudosphaera, Teleaulax, and Synechococcusdominated phytoplankton sequences (including chloroplasts) while SAR11,Sulfitobacter, andFluviicoladominated non-phytoplanktonBacteriaandArchaea. We observed short-lived increases of diatoms, mostlyPseudo-nitzschiaandChaetoceros, with quickly respondingBacteriaandArchaeaincludingFlavobacteriaceae(Polaribacter&Formosa),Roseovarius, andEuryarchaeota(MGII), notably the exact amplicon sequence variants we observed responding similarly to another diatom bloom nearby, three years prior. We observed correlations representing known interactions among abundant phytoplankton rRNA sequences, demonstrating the biogeochemical and ecological relevance of such interactions: 1) The kleptochloroplastidic ciliateMesodinium18S rRNA gene sequences and a singleTeleaulaxtaxon (via 16S rRNA gene sequences) were correlated (Spearmanr=0.83) yet uncorrelated to aTeleaulax18S rRNA gene OTU, or any other taxon (consistent with a kleptochloroplastidic or karyoklepty relationship) and 2) the photosynthetic prymnesiophyteBraarudosphaera bigelowiiand two strains of diazotrophic cyanobacterium UCYN-A were correlated and each taxon was also correlated to other taxa, includingB. bigelowiito a verrucomicrobium and a dictyochophyte phytoplankter (allr> 0.8). We also report strong correlations (r> 0.7) between various ciliates, bacteria, and phytoplankton, suggesting interactions via currently unknown mechanisms. These data reiterate the utility of high-frequency time-series to show rapid microbial reactions to stimuli, and provide new information aboutin-situdynamics of previously recognized and hypothesized interactions.

Distribution of planktonic biogenic carbonate organisms in the Southern Ocean south of Australia: a baseline for ocean acidification impact assessment

The Southern Ocean provides a vital service by absorbing about one sixth of humankind's annual emissions of CO2. This comes with a cost – an increase in ocean acidity that is expected to have negative impacts on ocean ecosystems. The reduced ability of phytoplankton and zooplankton to precipitate carbonate shells is a clearly identified risk. The impact depends on the significance of these organisms in Southern Ocean ecosystems, but there is very little information on their abundance or distribution. To quantify their presence, we used coulometric measurement of particulate inorganic carbonate (PIC) on particles filtered from surface seawater into two size fractions: 50–1000 μm to capture foraminifera (the most important biogenic carbonate forming zooplankton) and 1–50 μm to capture coccolithophores (the most important biogenic carbonate forming phytoplankton). Ancillary measurements of biogenic silica (BSi) and particulate organic carbon (POC) provided context, as estimates of the abundance of diatoms (the most abundant phytoplankton in polar waters), and total microbial biomass, respectively. Results for 9 transects from Australia to Antarctica in 2008–2015 showed low levels of PIC compared to northern hemisphere polar waters. Coccolithophores slightly exceeded the biomass of diatoms in Subantarctic waters, but their abundance decreased more than 30-fold poleward, while diatom abundances increased, so that on a molar basis PIC was only 1 % of BSi in Antarctic waters. This limited importance of coccolithophores in the Southern Ocean is further emphasized in terms of their associated POC, representing less than 1 % of total POC in Antarctic waters and less than 10 % in Subantarctic waters. NASA satellite ocean colour based PIC estimates were in reasonable agreement with (though somewhat higher than) the shipboard results in Subantarctic waters, but greatly over-estimated PIC in Antarctic waters. Contrastingly, the NASA Ocean Biogeochemical Model (NOBM) shows coccolithophores as overly restricted to Subtropical and northern Subantarctic waters. The cause of the strong southward decrease in PIC abundance in the Southern Ocean is not yet clear. Poleward decrease in pH is small and while calcite saturation decreases strongly southward it remains well above saturation (> 2). Nitrate and phosphate variations would predict a poleward increase. Temperature and competition with diatoms for limiting iron appear likely to be important. While the future trajectory of coccolithophore distributions remains uncertain, their current low abundances suggest small impacts on overall Southern Ocean pelagic ecology.

Plankton population and physico-chemical properties of a lake of Jahangirnagar University campus, Bangladesh at various lunar rhythms

Planktonic biomass and physico-chemical properties of water from a lake at Jahangirnagar University, Bangladesh were studied during new moon, first quarter, full moon and last quarter phases from 16th June to 15th July 2015. Twenty four species of phytoplankton belonging to Chlorophyceae, Bacillariophyceae and Euglenophyceae were recorded. Maximum abundance (162-301 unit/l) of Chlorophyceae was recorded in first quarter phase followed by full moon phase (112-224 unit/l), new moon phase (85-222unit/l) and last quarter phase (60-125 unit/l), respectively. Chlorella vulgaris and Biddulphia aurita were the most abundant phytoplankton throughout the lunar period. Among the zooplankton, 5 species of Protozoa, 2 species of Rotifer, 3 species of Cladocera and 1 species of Ostracoda were recorded. Highest zooplankton was recorded in full moon phase (54-105 unit/l) and Daphnia cephalata was the most abundant species throughout the lunar cycle. Physico-chemical parameters indicate that the water temperature, colour, odour and pH were almost similar throughout the lunar cycle, whereas maximum dissolved oxygen (7.16 mg/l) and minimum (4.43 mg/l) were found during the last quarter and the full moon phase, respectively. The highest content of free carbon dioxide (4.36 mg/l) and chloride (22.8 mg/l) were recorded during first quarter and full moon phase accordingly.Jahangirnagar University J. Biol. Sci. 4(2): 31-36, 2015 (December)

The effects of salinity on plankton and benthic communities in the Great Salt Lake, Utah, USA: a microcosm experiment

Saline lakes change in size and salinity because of natural climate variability and especially from inflow diversions, which threaten life in these waters. We conducted a microcosm experiment in 12 L containers using organisms from the Great Salt Lake to determine how salinities ranging from 10 to 275 g·L−1 influenced the ecosystem. After 30 days, brine shrimp (Artemia franciscana) were nearly absent in salinities of 10 g·L−1 (where fish survived) and >225 g·L−1. As salinities increased from 75 to 225 g·L−1, final masses decreased 60% and their total biomass decreased fourfold. Copepod and rotifer biomasses were negligible at salinities >50 g·L−1. Brine fly (Ephydra gracilis) final biomass decreased 45% as salinity increased from 50 to 250 g·L−1. When Artemia and other grazers were abundant, phytoplankton chlorophyll levels were near 4.0 μg·L−1, but when grazing rates declined at higher salinities, phytoplankton chlorophyll increased to 130 μg·L−1. Mean periphyton chlorophyll levels showed the reverse pattern. Denitrification decreased total N concentrations during the experiment, resulting in final N:P ratios indicative of algal nitrogen limitation. The microcosm experiment demonstrated the strong influence of salinity on the entire ecosystem and highlighted the need for careful management of salt lakes to maintain appropriate salinities.