ABSTRACT

Microplastics, small pieces of plastic (<5mm), are the most common type of marine debris. Nearly 1000 marine species ingest microplastics, and the effects on the food web and ecosystem is of increasing concern. This has implications for the Monterey Bay National Marine Sanctuary (MBNMS) because of the sanctuary’s mandate to understand and protect this area of national significance. The vertical distribution (5-1000m) of microplastics within the bay has been recently reported, finding the highest concentrations (15 particles m-3) at 200m depth, with higher concentrations of microplastics in offshore samples as compared to nearshore samples (Choy et al., 2019). To contribute to the limited research concerning microplastics in the MBNMS, we sought to understand the concentrations of microplastics surface seawater samples. In the summers of 2017 and 2018, we collected surface water samples using a manta trawl net (355mm mesh size) from two nearshore locations (Santa Cruz Boardwalk and Marina Sewage Outfall) and two offshore locations (Sur Ridge and Davidson Seamount) within the MBNMS. To isolate and extract synthetic material from our samples, we developed a process of density separation, chemical digestion, and vacuum filtration. We then used epifluorescence microscopy and ImageJ software to quantify the number of microplastics per cubic liter[MOU1]  of seawater. To link the polymer type of our a subset of our samples to their plastic source, we used Fourier-transform infrared spectroscopy (FT-IR). Our results will provide vital baseline information on the extent of microplastic pollution in the surface waters of the MBNMS at nearshore and offshore locations.

ABSTRACT

Climate change is expected to intensify upwelling in the California Current System, exposing nearshore fishes to more frequent periods of hypoxia (low dissolved oxygen) and high pCO~2~ (low pH). Rockfish are speciose and have long life histories making them beneficial to study. Additionally, as a part of the ground fish fishery, they are ecologically and economically important. They serve as predator and prey in all of their different life stages. To understand how gopher rockfish may fare in future upwelling conditions, wWe examined the effects of extreme upwelling conditions on the energetic demands of juvenile gopher rockfish (Sebastes carnatus) by measuring ventilation rates during a short-term laboratory upwelling simulation. We held fish (n=4-5/treatment) in one of two different treatments, simulating extreme upwelling (7.3 pH; 2.0 mg/L DO) or ambient conditions (8.0 pH; 8.0 mg/L DO) for four days. We then placed the upwelling group in an ambient treatment for an additional five days to simulate a subsequent relaxation event. Ventilation rates were measured in both groups at the end of each phase by averaging opercular beats per minute (bpm) over three one-minute intervals during a 30-minute time period. Fish in the upwelling treatment had ventilation rates ~50-60% higher than the control treatment (~50 bpm; two sample t-test: p-value < 0.001). After a 5 day recovery period, ventilation rates returned to levels associated with ambient conditions (~30 bpm; p-value = 0.11). Exposure to short-term upwelling events is likely to pose a major energetic cost to juvenile gopher rockfish and, although fish appeared to recover within a few days, longer-term sublethal effects such as changes in gene expression related to ion regulation and immune response may persist. Quantifying the energetic costs associated with exposure to future upwelling conditions can help predict the fate of rockfish populations under climate change.

ABSTRACT

Pterygophora californica is an understory kelp with a stipe that grows biannual rings.  Pterygophora is an important habitat-forming species of California kelp forests that provides shelter and a source of organic material for many organisms. Due to the thallus structures’ long lifespan, more insight about the history of ocean conditions and kelp forest habitats can be gained by understanding Pterygophora’s rings. These rings and their patterns may be used to determine ocean conditions such as temperature, nutrients, and light variability indicative of climate related events. Pterygophora thalli were collected from Stillwater Cove, Carmel, California in July 2017. Sections of the stipe are being cross-sectioned, stained, and analyzed under a compound microscope. Samples will be examined for differences in cell tissue between thalli and within a thallus. Individual ring morphology and composition patterns will be documented and also used in an attempt to backtrack through the life of each thallus. If able to identify specific years using ring analysis data, these years will be cross-referenced with sea surface temperatures recorded by the National Oceanic and Atmospheric Administration (NOAA). This method will be used to determine any correlation with climate change and/or El Niño events.