The Occurrence of Karenia species in mid-Atlantic coastal waters: Data from the Delmarva Peninsula, USA.

A bloom of Karenia papilionacea that occurred along the Delaware coast in late summer of 2007 was the first Karenia bloom reported on the Delmarva Peninsula (Delaware, Maryland, and Virginia, USA). Limited spatial and temporal monitoring conducted by state agencies and citizen science groups since 2007 have documented that several Karenia species are an annual component of the coastal phytoplankton community along the Delmarva Peninsula, often present at background to low concentrations (100 to 10,000 cells L-1). Blooms of Karenia (> 105 cells L-1) occurred in 2010, 2016, 2018, and 2019 in different areas along the Delmarva Peninsula coast. In late summer and early autumn of 2017, the lower Chesapeake Bay experienced a K. papilionacea bloom, the first recorded in Bay waters. Blooms typically occurred summer into autumn but were not monospecific; rather, they were dominated by either K. mikimotoi or K. papilionacea, with K. selliformis, K. brevis-like cells, and an undescribed Karenia species also present. Cell concentrations during these mid-Atlantic Karenia spp. blooms equalled concentrations reported for other Karenia blooms. However, the negative impacts to environmental and human health often associated with Karenia red tides were not observed. The data compiled here report on the presence of multiple Karenia species in coastal waters of the Delmarva Peninsula detected through routine monitoring and opportunistic sampling conducted between 2007 and 2022, as well as findings from research cruises undertaken in 2018 and 2019. These data should be used as a baseline for future phytoplankton community analyses supporting coastal HAB monitoring programs.

Co-occurrence of marine and freshwater phycotoxins in oysters, and analysis of possible predictors for management.

Oysters (Crassostrea virginica) were screened for 12 phycotoxins over two years in nearshore waters to collect baseline phycotoxin data and to determine prevalence of phycotoxin co-occurrence in the commercially and ecologically-relevant species. Trace to low concentrations of azaspiracid-1 and -2 (AZA1, AZA2), domoic acid (DA), okadaic acid (OA), and dinophysistoxin-1 (DTX1) were detected, orders of magnitude below seafood safety action levels. Microcystins (MCs), MC-RR and MC-YR, were also found in oysters (maximum: 7.12 µg MC-RR/kg shellfish meat wet weight), warranting consideration of developing action levels for freshwater phycotoxins in marine shellfish. Oysters contained phycotoxins that impair shellfish health: karlotoxin1-1 and 1-3 (KmTx1-1, KmTx1-3), goniodomin A (GDA), and pectenotoxin-2 (PTX2). Co-occurrence of phycotoxins in oysters was common (54%, n = 81). AZAs and DA co-occurred most frequently of the phycotoxins investigated that are a concern for human health (n = 13) and PTX2 and KmTxs co-occurred most frequently amongst the phycotoxins of concern for shellfish health (n = 9). Various harmful algal bloom (HAB) monitoring methods and tools were assessed for their effectiveness at indicating levels of phycotoxins in oysters. These included co-deployed solid phase adsorption toxin tracking (SPATT) devices, toxin levels in particulate organic matter (POM, >1.5 µm) and whole water samples and cell concentrations from water samples as determined by microscopy and quantitative real-time PCR (qPCR). The dominant phycotoxin varied between SPATTs and all other phycotoxin sample types, and out of the 11 phycotoxins detected in oysters, only four and seven were detected in POM and whole water respectively, indicating phycotoxin profile mismatch between ecosystem compartments. Nevertheless, there were correlations between DA in oysters and whole water (simple linear regression [LR]: R2 = 0.6, p < 0.0001, n = 40), and PTX2 in oysters and SPATTs (LR: R2 = 0.3, p = 0.001, n = 36), providing additional monitoring tools for these phycotoxins, but oyster samples remain the best overall indicators of seafood safety.

Review of harmful algal bloom effects on birds with implications for avian wildlife in the Chesapeake Bay region.

The Chesapeake Bay, along the mid-Atlantic coast of North America, is the largest estuary in the United States and provides critical habitat for wildlife. In contrast to point and non-point source release of pesticides, metals, and industrial, personal care and household use chemicals on biota in this watershed, there has only been scant attention to potential exposure and effects of algal toxins on wildlife in the Chesapeake Bay region. As background, we first review the scientific literature on algal toxins and harmful algal bloom (HAB) events in various regions of the world that principally affected birds, and to a lesser degree other wildlife. To examine the situation for the Chesapeake, we compiled information from government reports and databases summarizing wildlife mortality events for 2000 through 2020 that were associated with potentially toxic algae and HAB events. Summary findings indicate that there have been few wildlife mortality incidents definitively linked to HABs, other mortality events that were suspected to be related to HABs, and more instances in which HABs may have indirectly contributed to or occurred coincident with wildlife mortality. The dominant toxins found in the Chesapeake Bay drainage that could potentially affect wildlife are microcystins, with concentrations in water approaching or exceeding human-based thresholds for ceasing recreational use and drinking water at a number of locations. As an increasing trend in HAB events in the U.S. and in the Chesapeake Bay have been reported, additional information on HAB toxin exposure routes, comparative sensitivity among species, consequences of sublethal exposure, and better diagnostic and risk criteria would greatly assist in predicting algal toxin hazard and risks to wildlife.

Understanding controls on Margalefidinium polykrikoides blooms in the lower Chesapeake Bay.

A time-dependent model of Margalefidinium polykrikoides, a mixotrophic dinoflagellate, cell growth was implemented to assess controls on blooms in the Lafayette River, a shallow, tidal sub-tributary of the lower Chesapeake Bay. Simulated cell growth included autotrophic and heterotrophic contributions. Autotrophic cell growth with no nutrient limitation resulted in a bloom but produced chlorophyll concentrations that were 45% less than observed bloom concentrations (~80 mg Chl m-3 vs. 145 mg Chl m-3) and a bloom progression that did not match observations. Excystment (cyst germination) was important for bloom initiation, but did not influence the development of algal biomass or bloom duration. Encystment (cyst formation) resulted in small losses of biomass throughout the bloom but similarly, did not influence M. polykrikoides cell density or the duration of blooms. In contrast, the degree of heterotrophy significantly impacted cell densities achieved and bloom duration. When heterotrophy contributed a constant 30% to cell growth, and dissolved inorganic nitrogen was not limiting, simulated chlorophyll concentrations were within those observed during blooms (maximum ~140 mg Chl m-3). However, nitrogen limitation quenched the maximum chlorophyll concentration by a factor of three. Specifying heterotrophy as an increasing function of nutrient limitation, allowing it to contribute up to 50% and 70% of total growth, resulted in simulated maximum chlorophyll concentrations of 90 mg Chl m-3 and 180 mg Chl m-3, respectively. This suggested that blooms of M. polykrikoides in the Lafayette River are fortified and maintained by substantial heterotrophic nutritional inputs. The timing and progression of the simulated bloom was controlled by the temperature range, 23 °C to 28 °C, that supports M. polykrikoides growth. Temperature increases of 0.5 °C and 1.0 °C, consistent with current warming trends in the lower Chesapeake Bay due to climate change, shifted the timing of bloom initiation to be earlier and extended the duration of blooms; maximum bloom magnitude was reduced by 50% and 65%, respectively. Warming by 5 °C suppressed the summer bloom. The simulations suggested that the timing of M. polykrikoides blooms in the Lafayette River is controlled by temperature and the bloom magnitude is determined by trade-offs between the severity of nutrient limitation and the relative contribution of mixotrophy to cell growth.

Spatiotemporal distribution of phycotoxins and their co-occurrence within nearshore waters.

Harmful algal blooms (HABs), varying in intensity and causative species, have historically occurred throughout the Chesapeake Bay, U.S.; however, phycotoxin data are sparse. The spatiotemporal distribution of phycotoxins was investigated using solid-phase adsorption toxin tracking (SPATT) across 12 shallow, nearshore sites within the lower Chesapeake Bay and Virginia's coastal bays over one year (2017-2018). Eight toxins, azaspiracid-1 (AZA1), azaspiracid-2 (AZA2), microcystin-LR (MC-LR), domoic acid (DA), okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2), and goniodomin A (GDA) were detected in SPATT extracts. Temporally, phycotoxins were always present in the region, with at least one phycotoxin group (i.e., consisting of OA and DTX1) detected at every time point. Co-occurrence of phycotoxins was also common; two or more toxin groups were observed in 76% of the samples analyzed. Toxin maximums: 0.03 ng AZA2/g resin/day, 0.25 ng DA/g resin/day, 15 ng DTX1/g resin/day, 61 ng OA/g resin/day, 72 ng PTX2/g resin/day, and 102,050 ng GDA/g resin/day were seasonal, with peaks occurring in summer and fall. Spatially, the southern tributary and coastal bay regions harbored the highest amount of total phycotoxins on SPATT over the year, and the former contained the greatest diversity of phycotoxins. The novel detection of AZAs in the region, before a causative species has been identified, supports the use of SPATT as an explorative tool in respect to emerging threats. The lack of karlotoxin in SPATT extracts, but detection of Karlodinium veneficum by microscopy, however, emphasizes that this tool should be considered complementary to, but not a replacement for, more traditional HAB management and monitoring methods.

Collection system investigation microbial source tracking (CSI-MST): Applying molecular markers to identify sewer infrastructure failures.

Collection System Investigation Microbial Source Tracking (CSI-MST) is a novel, sensitive approach for identifying sewer infrastructure deficiencies using molecular markers. This method requires both a detailed understanding of collection and conveyance system infrastructure and quickly turned around molecular data to advise an adaptive, targeted in-pipe approach to detect deficiencies. Here we explain the CSI-MST approach and provide several case study examples of how this approach can be adapted to different scale watersheds to identify potential sewer infrastructure issues. This approach has been used to locate and confirm the remediation of numerous needed infrastructure repairs in the southeastern Virginia region. The selected case studies presented here serve as a proof of concept-this methodology can be adopted by other utilities and municipalities to address necessary wastewater infrastructure repairs in different regions.

Characterization of Dinophysis spp. (Dinophyceae, Dinophysiales) from the mid-Atlantic region of the United States1.

Due to the increasing prevalence of Dinophysis spp. and their toxins on every US coast in recent years, the need to identify and monitor for problematic Dinophysis populations has become apparent. Here, we present morphological analyses, using light and scanning electron microscopy, and rDNA sequence analysis, using a ~2-kb sequence of ribosomal ITS1, 5.8S, ITS2, and LSU DNA, of Dinophysis collected in mid-Atlantic estuarine and coastal waters from Virginia to New Jersey to better characterize local populations. In addition, we analyzed for diarrhetic shellfish poisoning (DSP) toxins in water and shellfish samples collected during blooms using liquid-chromatography tandem mass spectrometry and an in vitro protein phosphatase inhibition assay and compared this data to a toxin profile generated from a mid-Atlantic Dinophysis culture. Three distinct morphospecies were documented in mid-Atlantic surface waters: D. acuminata, D. norvegica, and a "small Dinophysis sp." that was morphologically distinct based on multivariate analysis of morphometric data but was genetically consistent with D. acuminata. While mid-Atlantic D. acuminata could not be distinguished from the other species in the D. acuminata-complex (D. ovum from the Gulf of Mexico and D. sacculus from the western Mediterranean Sea) using the molecular markers chosen, it could be distinguished based on morphometrics. Okadaic acid, dinophysistoxin 1, and pectenotoxin 2 were found in filtered water and shellfish samples during Dinophysis blooms in the mid-Atlantic region, as well as in a locally isolated D. acuminata culture. However, DSP toxins exceeded regulatory guidance concentrations only a few times during the study period and only in noncommercial shellfish samples.

Cyanobacteria and cyanotoxins at the river-estuarine transition.

We examined seasonal and longitudinal patterns in the occurrence of toxic cyanobacteria in the James River Estuary (Virginia). Highest chlorophyll and cyanobacteria levels were observed in the tidal freshwater segment, particularly during dry summers when freshwater replacement time was long. Cyanobacteria accounted for a small proportion of phytoplankton biomass (7-15%), and Microcystis comprised a small proportion of the cyanobacteria (<1%). Despite this, measureable levels of microcystin were commonly observed in water (>85% of samples in July, August and September), fish tissues (87% of planktivorous fishes) and shellfish (83% of individuals). Generic indicators of algal blooms (chlorophyll and algal biomass) had limited utility for predicting microcystin concentrations. However, chlorophyll was found to be a useful predictor for the probability of exceeding specific toxin thresholds. Tissue microcystin concentrations were highest in fish and shellfish collected from the tidal fresh segment, but were detectable in biota collected from the oligohaline at distances 50 km seaward.

Emergence of Algal Blooms: The Effects of Short-Term Variability in Water Quality on Phytoplankton Abundance, Diversity, and Community Composition in a Tidal Estuary.

Algal blooms are dynamic phenomena, often attributed to environmental parameters that vary on short timescales (e.g., hours to days). Phytoplankton monitoring programs are largely designed to examine long-term trends and interannual variability. In order to better understand and evaluate the relationships between water quality variables and the genesis of algal blooms, daily samples were collected over a 34 day period in the eutrophic Lafayette River, a tidal tributary within Chesapeake Bay's estuarine complex, during spring 2006. During this period two distinct algal blooms occurred; the first was a cryptomonad bloom and this was followed by a bloom of the mixotrophic dinoflagellate, Gymnodinium instriatum. Chlorophyll a, nutrient concentrations, and physical and chemical parameters were measured daily along with phytoplankton abundance and community composition. While 65 phytoplankton species from eight major taxonomic groups were identified in samples and total micro- and nano-phytoplankton cell densities ranged from 5.8 × 106 to 7.8 × 107 cells L-1, during blooms, cryptomonads and G. instriatum were 91.6% and 99.0%, respectively, of the total phytoplankton biomass during blooms. The cryptomonad bloom developed following a period of rainfall and concomitant increases in inorganic nitrogen concentrations. Nitrate, nitrite and ammonium concentrations 0 to 5 days prior were positively lag-correlated with cryptomonad abundance. In contrast, the G. insriatum bloom developed during periods of low dissolved nitrogen concentrations and their abundance was negatively correlated with inorganic nitrogen concentrations.

Morphological variation and phylogenetic analysis of the dinoflagellate Gymnodinium aureolum from a tributary of Chesapeake Bay.

Cultures of four strains of the dinoflagellate Gymnodinium aureolum (Hulburt) G. Hansen were established from the Elizabeth River, a tidal tributary of the Chesapeake Bay, USA. Light microscopy, scanning electron microscopy, nuclear-encoded large sub-unit rDNA sequencing, and culturing observations were conducted to further characterize this species. Observations of morphology included: a multiple structured apical groove; a peduncle located between the emerging points of the two flagella; pentagonal and hexagonal vesicles on the amphiesma; production and germination of resting cysts; variation in the location of the nucleus within the center of the cell; a longitudinal ventral concavity; and considerable variation in cell width/length and overall cell size. A fish bioassay using juvenile sheepshead minnows detected no ichthyotoxicity from any of the strains over a 48-h period. Molecular analysis confirmed the dinoflagellate was conspecific with G. aureolum strains from around the world, and formed a cluster along with several other Gymnodinium species. Morphological evidence suggests that further research is necessary to examine the relationship between G. aureolum and a possibly closely related species Gymnodinium maguelonnense.