Lead Organizer: Kyle Emery, University of California, Los Angeles (kyleemery@ucla.edu)
Co-organizers:
Lluis Gomez-Pujol, University of the Balearic Islands (lgomez-pujol@uib.es)
Presentations
06:30 PM
Global warming affects coastal ecosystems more than anthropogenic nutrient reduction (4634)
Primary Presenter: Shubham Krishna, Helmholtz Center Hereon (Shubham.Krishna@hereon.de)
The combined effects of global warming and anthropogenic pressures such as fishery and (de)eutrophication on marine and coastal ecosystems are difficult to assess and can be counterintuitive. For example, in the coastal Southern North Sea (SNS), observed chlorophyll concentrations increased in spite of a significant reduction in nutrient loads. Most models so far failed to reproduce this trend because they assume a bottom-up control of ecosystem dynamics. Here, we use a coupled model system (MOSSCO-GETM-MAECS) with a realistic representation of turbidity in near-coast waters. High turbidity not only impedes autotrophic growth due to light limitation but also creates a refuge for juvenile fish so that carnivorous grazing on zooplankton increases towards the coast. We validate long-term simulations of the SNS against satellite and in-situ observations, and show that climate warming has intensified temperature-dependent carnivory, which through reduced herbivory positively affects net phytoplankton growth. The simulated long-term change in coastal carnivory matches well an observed increase in juvenile fish biomass. Our study highlights the relevance of turbidity and resulting top-down control for the sensitivity of marine ecosystems to global change.
06:30 PM
Exploring the Ideal Substrate and Watering Conditions for Mangrove Seedling Survival and Growth in a Controlled Setting (4650)
Primary Presenter: Lizmar Luna, University of Puerto Rico in Humacao (lizmar.luna@upr.edu)
Avicennia germinans (black mangrove) is specifically adapted to the estuarine environments off the coast of the southern United States and in the tropical regions of the Caribbean and Eastern Africa. Black mangroves are viviparous, with propagules germinating on the parent tree followed by a floating dispersal stage. Once the propagules reach a suitable environment, the seed will take root. Many abiotic factors may influence the successful establishment of propagules in the field, and greenhouse studies are one tool to investigate the importance of various abiotic conditions. However, the methods for establishing seedlings in order to conduct effective greenhouse studies are not well standardized. The purpose of this research was to understand mangrove seedling response to different greenhouse conditions, including distinct substrates and watering regimes. Seedlings were collected from the field and transplanted into four different substrate conditions: sand, nutrient-amended sand, a mixture of sand and potting soil, and potting soil. As for the watering conditions used, there were non-flooded conditions and semi-flooded conditions. Over the course of three weeks, a rapid decline of seedling health, as measured with an index of leaf color, was observed across all experimental treatments. However, the sand-only substrate (without nutrient or potting soil amendments) had the least dramatic decline, suggesting that the sand medium, which was most similar to the substrate from the field, was the most ideal out of the four. There were smaller differences among watering regimes, where a decline was seen for the non-flooded seedlings after two weeks, and the flooded conditions remained more stable. The rapid overall seedling decline suggests transplant shock, indicating that effective greenhouse studies should germinate seeds in pots rather than collecting seedlings directly from the field.
06:30 PM
Spatial patterns of pink lesions on the massive coral Porites spp. during 2 outbreaks in Moorea, French Polynesia suggest a link to anthropogenic stress (4658)
Primary Presenter: Ashlyn Ford, University of California - Los Angeles (ashlynford@g.ucla.edu)
outbreaks may be increasing in marine systems. Thus, understanding spatial patterns of infection and associated factors that may promote outbreaks is increasingly important in the Anthropocene. Coral in the genus Porites respond to infection by forming raised pink polyps. In July of 2016 and 2021, we observed an outbreak of pink lesions (PL) on coral in the north shore of Moorea, French Polynesia. We quantified spatial patterns in prevalence and dispersion within two bays with developed watersheds, hypothesizing prevalence (% infected per site) and dispersion (pattern on individual colonies) would be highest within the impacted bays. Also quantified dispersion at a high prevalence site using Mean to Variance Ratio. Found prevalence was highest in the bays. At low and medium prevalence sites in 2016, 15-20% of colonies had PL compared to 11% in 2021, while high prevalence sites exceeded 90% infected in both years. Overall, aggregation decreased with prevalence, with the low prevalence site highly clustered and the high prevalence site randomly dispersed. Thus, it is unlikely for a colony to be heavily infected unless surrounded by infected colonies. At one impacted site, prevalence was higher in 2021 than in 2016, which could infer that human development has worsened conditions in that area or outbreak cycles can be site dependent. Overall, our results imply PLs on Porites of Moorea are associated with anthropogenic stressors, which contrasts patterns found in other reef systems.
06:30 PM
SILICONE RUBBER AS A PASSIVE SAMPLER FOR MULTITARGET ANALYSIS (5024)
Primary Presenter: Adrielle Martins, Federal University of Bahia (adriellebmartins@gmail.com)
The analysis of non-polar organic compounds in aquatic matrices presents several challenges due to factors such as the low concentrations and mixtures of contaminants, the presence of interferences, and the requirement of a large sample volume. Developing methods capable of simultaneously analyzing multiple classes of compounds at relatively low concentrations is a critical issue in environmental science. The aim of this study was to develop an extraction method for the simultaneous analysis of persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs), and selected emerging contaminants (organic UV filters and fragrances) in aquatic systems using passive samplers. The silicone rubber passive samplers were fortified with a solution containing a known concentration of the selected contaminants. Extraction tests were performed using ultrasound with different mixtures of solvents: dichloromethane:hexane (v:v, 1:1, 2:1), methanol:dichloromethane (v:v, 1:1), acetonitrile:methanol (v:v, 3:1, 1:1). Analyses were performed in a gas chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that the best mixture of solvents tested was dichloromethane:hexane with a volume ratio of 2:1, which had analyte recovery ranging from 42-133% and relative standard deviation lower than 25%. The method will be validated in the field through the exposure of passive samplers in coastal regions, contributing to the understanding of the occurrence, spatial and temporal variations, as well as the potential sources of contaminants in seawater.
06:30 PM
Grazing From Diadema antillarum and Tripneustes ventricosus Reduce the Cover of the Invasive Seagrass, Halophila stipulacea, in the Caribbean (5581)
Primary Presenter: Hunter Howard, University of Puerto Rico Mayagüez (hunterbhoward@gmail.com)
Caribbean seagrass beds are becoming increasingly populated by the invasive seagrass Halophila stipulacea that has negative impacts on native seagrass. Restoring herbivore populations, such as the sea urchin, Diadema antillarum, has significantly reduced nuisance algae on many coral reefs in Puerto Rico. D. antillarum can graze heavily on seagrass as well. However, culturing and restoring D. antillarum comes with challenges. In this study, another essential sea urchin, Tripneustes ventricosus, was released to seagrass beds to measure their grazing impacts on the benthic composition. The grazing behaviors of D. antillarum and T. ventricosus were studied in H. stipulacea seagrass beds of Isla Magueyes, Boqueron, and Laurel in Puerto Rico using closed cage systems. The D. antillarum and T. ventricosus were allowed to feed on the H. stipulacea for one month, with photoquadrats being used to record their herbivory once a week. Preliminary findings suggest that D. antillarum and T. ventricosus have the ability to graze H. stipulacea to bare sediment in three weeks. In addition to this, substrate percent cover increased after the inclusion of the herbivores while live Halophila cover decreased. Given the preliminary results of this study, D. antillarum and T. ventricosus may be effective herbivores for restoration efforts. Releasing D. antillarum and T. ventricosus may reduce the invasive seagrass, H. stipulacea, and other competitive algal species on coral reefs in Puerto Rico.
06:30 PM
THE COASTAL FRONT MODULATES THE TIMING AND MAGNITUDE OF SPRING PHYTOPLANKTON BLOOMS IN THE YELLOW SEA (5722)
Primary Presenter: TING LYU, University of Geneva (lvting26@163.com)
Major seasonal quasi-stationary fronts on shelves play an important role in regulating the spatiotemporal variations in the phytoplankton community. However, knowledge of their effects on the timing and magnitude of spring phytoplankton bloom (SPB) remains limited. Here, based on decadal satellite data (2003–2020), we examine the climatological relationship between the Shandong coastal front (SCF) and SPB in the Yellow Sea. The results show that the onset of SPB occurs either in March (∼56% of the seasons examined) or in April (44%). The peak of SPB most often occurs in April (∼56% of the seasons examined) or is advanced to March (16%) or delayed to May (28%), and that the peak ranges from 1.04 to 2.54 mg Chl-a m−3. The onset of SPB matches with lower turbulence, particularly when the rate of generation of turbulent kinetic energy (TKERT) reaches zero. A higher magnitude of bloom is associated with a greater change in front and a lower TKERT. The in situ observations along the SCF transects in the Yellow Sea indicate that weakened SCF in spring associated with a shallower mixing layer enhances the transport of nutrients from the coastal to the shelf waters. Weakened frontal structure and atmospheric forcing in spring can further increase the water stability and decrease turbulence in the upper waters. The variation in hydrodynamic conditions allows shelf phytoplankton to stay longer in the upper waters with sufficient light and nutrients and consequently generate a Chl-a peak. The results suggest that the seasonal changes in front intensity and structure and turbulence are important prerequisites for initiating SPB on the shelf, and that further determines the magnitude of SPB.
06:30 PM
Biosedimentology of the Posidonia oceanica seagrass meadows fairy circles (6571)
Primary Presenter: Lluis GOMEZ-PUJOL, University of the Balearic Islands (lgomez-pujol@uib.es)
The seagrass Posidonia oceanica (L. delile), endemic to the Mediterranean, Sea is the dominant species in the meadows that characterize the sandy and rocky coastal bottoms in Western Mediterranean. The meadows present an intense cover of the seabed between -4 and -40 m, although this pattern is altered by patches of irregular shapes, where the seabed is free of vegetation and which are known as seagrass meadow fairy circles. None study has addressed the irregularity of fairy circles sediments and what it implies in ecological and sedimentological terms. The present work characterizes the texture and composition of the sediment accumulated in the fairy circles and compares it with other nearby sub-environments from the samplings carried out in two locations in Mallorca, one from Menorca, and one from Girona. The results describe differences in the size of the sediment and in the composition between the interior and the margins of the fairy circles, as well as with respect to the interior of the meadow or the free accumulations of sand close to the fairy circle. As well as a differentiated spatial distribution of the sedimentary facies. The samples located inside the meadow show finer texture values associated with a predominant composition of foraminifera and undifferentiated bioclasts, while the samples more exposed to waves, such as those on the margins or inside the fairy circles, tend to retain coarser sediments associated with a larger abundance of gastropod fragments.
06:30 PM
BOTTOM WATER SHADOWS OF SURFACE WATER CHANGES: NORTHERN GULF OF MEXICO HYPOXIC ZONE (6866)
Primary Presenter: R. Eugene Turner, Louisiana State University (euturne@lsu.edu)
Tipping points may occur where the diatom-based food web collapses, HABs bloom or when organisms can no longer accumulate calcium-carbonate structures with decreasing pH. One recent tipping point is from the northern Gulf of Mexico hypoxic zone. The total area of its size in late summer has been predicted with great fidelity (R2 = 0.85) using nitrogen loading from the Mississippi River 2-3 months earlier as the main driver. The prediction in 2022, however, severely over-estimated its actual size by 56% indicating that something was missing in the models Why? Thirty-seven years of data from monitoring the summer hypoxic zone size and water quality are reviewed. River water quality has not changed recently, but water temperature has been increasing (0.5 oC decade-1) with significant declines in surface and bottom Chlorophyll a and hypoxic zone size per N loading. The hypoxic zone size is not decreasing because of nutrient reductions, but because of climate change. A tipping point is indicated that may be common to similar warm and eutrophic coastal waters. Hypoxia and food web models based on a stationary equipoise of nutrient loadings and ratios in surface and bottom waters will likely be deficient as coastal waters warm further.
06:30 PM
Exploring Spatial and Temporal Differences Between High and Low Frequency Water Quality Data in Coastal Virginia (6920)
Primary Presenter: Emma Brahmey, University of Virginia (eb2vw@virginia.edu)
Water quality variables such as temperature, salinity, dissolved oxygen, chlorophyll-a, and apparent oxygen utilization are important biogeochemical measures of coastal water health, and accurate monitoring and modeling is vital in order to characterize the processes driving seasonal and geographic patterns. Using harmonic analysis, a method that fits sine and cosine functions to seasonally varying data, this project seeks to investigate the differences in harmonic elements (date and value of minimum/maximum and seasonal amplitude) on a spatial and temporal scale, specifically comparing subsampled short term high frequency (4-6 years of 15 minute resolution) to long term low frequency (30 years of quarterly sampled resolution) sites. At high frequency sites, error variability between successive years of simulated quarterly sampling are compared to full model values using novel methods of logarithmic regression. This information allows us to understand baseline seasonal patterns, and investigate deviations of those through anomalies. Diurnal anomalies are examined in both magnitude and directional changes due to weather factors based on a storm and seasonal scale. These correlations can inform us of potential disturbances in water quality that may become more severe and/or frequent as the amount and severity of storms and flooding increase due to global warming and sea level rise. This is a vital study due to the lack of modern research using harmonic analysis in coastal Virginia, as well as few papers regarding storm impacts on coastal water quality anomalies.
06:30 PM
ASSESSING THE ROLE OF SURFACE PROPERTIES IN MODULATING PARTICLE CAPTURE EFFICIENCY IN MUSSELS AND BENTHIC ASCIDIANS - AN IN SITU AND LABORATORY STUDY (6996)
Primary Presenter: Martina Capriotti, Univerisity of Connecticut (martina.capriotti12@gmail.com)
Prey capture in suspension feeders has previously been assumed to be based solely on particle size; however, recent studies indicate that similar-sized micron and submicron particles may be captured at different efficiencies and that interactions between surface properties of food particles and the feeding organ may have a significant effect on the capture efficiency. Amino sugars are common constituents on the cell surface of marine plankton. Their ability to interact with mucus lectins suggests they may have a role in food capture and selection in suspension feeders. We studied in situ modulation of capture efficiency of natural seston groups over several seasons in two groups of suspension feeders: mussels (Mytilus edulis and Geukensia demissa) and ascidians (Ciona intestinalis and Styela clava). In the laboratory, the same suspension feeders species were exposed to 0.3 -, 0.5 - and 1-µm polystyrene spheres uncoated or coated with the nonionic surfactant Poloxamer 188 (Pol) or the neoglycoprotein galactosamine-BSA (Gal). In most cases, pico-cyanobacteria were captured at a higher efficiency than larger nano-eukaryotic algae. Submicron Gal-coated microspheres were captured at a higher efficiency than uncoated or Pol-coated microspheres, reinforcing the concept that features other than size control feeding processes.
06:30 PM
THE LONGEVITY OF SUBTIDAL BLUE MUSSEL BEDS IN EUTROPIC COASTAL AREAS. (6998)
Primary Presenter: Isabelle Johansson, Denmark technical university (DTU aqua) (isjoh@aqua.dtu.dk)
Mussel populations (Mytilus edulis) around the coasts of Europe and the North Atlantic are often ephemeral and have notably experienced a large decline in abundance. Identifying factors that govern the fluctuation and longevity of mussel populations is important for the management of the fishery, setting conservation targets, and coastal restoration purposes. Since 1993, annual blue mussel stock surveys have been carried out in the Limfjorden, Denmark. We used the stock survey data combined with electronic monitoring fishing data and a Mechanistic Model for Limfjorden, providing environmental data, to investigate the longevity of subtidal mussel beds. Multiple factors were found to affect the longevity of subtidal mussel beds in Limfjorden. Our study reveals that predation by starfish, fishing activities, and consecutive days of oxygen depletion are significant factors, negatively impacting bed stability. Conversely, increased biomass and the presence of multiple cohorts demonstrate stabilizing effects on mussel beds. These analyses can help inform environmental, conservation, and fisheries managers on the long-term trends of population dynamics and factors contributing to the variability in population stability in the context of declining stocks.
CS039P Coastal Ecosystems
Description
Time: 6:30 PM
Date: 7/6/2023
Room: Mezzanine