Broad sampling and diverse biomarkers allow characterization of nearshore particulate organic matter

Lowe, Alexander T.; Galloway, Aaron W. E.; Yeung, J. Sean; Dethier, Megan N.; Duggins, David O.

doi:10.1111/oik.01392

Cited by 49 publications

(35 citation statements)

References 57 publications

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“…The total availability of PUFA to upper trophic level consumers decreased from the spring to the summer and fall, as the phytoplankton composition changed. Similar seasonal dynamics of PUFA have also been documented in other freshwater and coastal marine phytoplankton communities (Ahlgren et al 1997, Lowe et al 2014. In the summer the phytoplankton biomass was similar to that of spring samples, but the quality declined, because the proportion of DHA and EPA decreased.…”

Section: Fatty Acids and Phytoplankton In Moderately Humic Lakes: Comsupporting

confidence: 49%

“…Seston is highly variable, and in addition to phytoplankton, seston in both freshwater and marine habitats contains detritus and heterotrophs, which also contribute to the fatty acid composition (Bec et al 2010a, 2010b, Lowe et al 2014. In humic lakes, detritus is known to comprise of a wide variety of molecular components, including also free fatty acids (Schulten and Gleixner 1999).…”

Section: Discussionmentioning

confidence: 99%

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Inferring phytoplankton community composition with a fatty acid mixing model

et al. 2015

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Abstract. The taxon specificity of fatty acid composition in algal classes suggests that fatty acids could be used as chemotaxonomic markers for phytoplankton composition. The applicability of phospholipid-derived fatty acids as chemotaxonomic markers for phytoplankton composition was evaluated by using a Bayesian fatty acid-based mixing model. Fatty acid profiles from monocultures of chlorophytes, cyanobacteria, diatoms, euglenoids, dinoflagellates, raphidophyte, cryptophytes and chrysophytes were used as a reference library to infer phytoplankton community composition in five moderately humic, large boreal lakes in three different seasons (spring, summer and fall). The phytoplankton community composition was also estimated from microscopic counts. Both methods identified diatoms and cryptophytes as the major phytoplankton groups in the study lakes throughout the sampling period, together accounting for 54-63% of the phytoplankton. In addition, both methods revealed that the proportion of chlorophytes and cyanobacteria was lowest in the spring and increased towards the summer and fall, while dinoflagellates peaked in the spring. The proportion of euglenoids and raphidophytes was less than 8% of the phytoplankton biomass throughout the sampling period. The model estimated significantly lower proportions of chrysophytes in the seston than indicated by microscopic analyses. This is probably because the reference library for chrysophytes included too few taxa. Our results show that a fatty acid-based mixing model approach is a promising tool for estimating the phytoplankton community composition, while also providing information on the nutritional quality of the seston for consumers. Both the quantity and the quality of seston as a food source for zooplankton were high in the spring; total phytoplankton biomass was ;56 lg C L À1, and the physiologically important polyunsaturated fatty acids 20:5n-3 and 22:6n-3 comprised ;22% of fatty acids.

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Section: Fatty Acids and Phytoplankton In Moderately Humic Lakes: Comsupporting

confidence: 49%

Section: Discussionmentioning

confidence: 99%

Inferring phytoplankton community composition with a fatty acid mixing model

et al. 2015

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“…We used offshore POM (.4 km offshore) isotopic values as our measure of the pelagic producer base; however POM contains a mixture of benthic detritus and phytoplankton that cannot be easily separated (Lowe et al 2014), and phytoplankton C isotopic ratios may vary seasonally and with distance to shore (Kaehler et al 2006, Miller andPage 2012). Although the isotopic signatures of pelagic producers can be difficult to assign, two studies found very consistent values for POM off of Vancouver Island around À22 (Perry et al 1999, Ramshaw 2012).…”

Section: Effects Of Kelp-carbon and Trophic Position On Juvenile Rockmentioning

confidence: 99%

Indirect effects of sea otters on rockfish (Sebastes spp.) in giant kelp forests

Markel

Shurin

2015

Ecology

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Abstract. Sea otters are a classic example of a predator controlling ecosystem productivity through cascading effects on basal, habitat-forming kelp species. However, their indirect effects on other kelp-associated taxa like fishes are poorly understood. We examined the effects of sea otter (Enhydra lutris) reintroduction along the west coast of Vancouver Island, Canada on giant kelp (Macrocystis pyrifera) distributions and the trophic niches and growth of two common kelp forest fishes, black (Sebastes melanops) and copper (S. caurinus) rockfishes. We sampled 47 kelp forests, and found that red sea urchins (Strongylocentrotus franciscanus) were eliminated in the presence of otters, and that kelp forests were 3.7 times deeper and 18.8 times larger. Despite order-of-magnitude differences in kelp forest size, adult black and copper rockfishes contained less kelp-derived carbon in their tissues (as measured by stable isotopes of C and N) in regions with otters. Adults of both species had higher mean trophic positions in the presence of otters, indicating more frequent consumption of higher trophic level prey such as fishes. Smaller trophic niche space of rockfishes in the presence of otters indicated a higher degree of trophic specialization. Juvenile black rockfishes rapidly shifted to higher kelp-carbon contents, trophic positions, and body condition factors after settling in kelp forests. The relationships of growth to length, percentage of kelp carbon, and trophic position varied between the two regions, indicating that potential effects of kelp forest size on trophic ontogeny may also affect individual performance. Our results provide evidence that the indirect effects of otters on rockfishes arise largely through the creation of habitat for fishes and other prey rather than a direct trophic connection through invertebrates or other consumers of kelp productivity.

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“…Food availability, defined here as the abundance and quality of energetic sources to suspension‐feeders, in coastal marine ecosystems is composed of many sources of primary production including autochthonous and allochthonous organic matter (Miller et al ; Lowe et al ). The quality of a food source is a function of both the biochemical composition and ease of consumption (reviewed in Shin et al ; Müller‐Navarra ; Wagner et al ).…”

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confidence: 99%

Improved marine‐derived POM availability and increased pH related to freshwater influence in an inland sea

2016

Self Cite

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Rapid changes, including warming and freshening, are occurring in coastal marine ecosystems worldwide. These environmental changes have the potential to alter ecosystem energetics by influencing availability of food sources and organism physiology. We investigated the influence of oceanographic variability on food availability and quality to benthic and pelagic suspension-feeders using detailed observations of phytoplankton, particulate organic matter (POM) detritus, and diverse biomarkers (fatty acids and carbon, nitrogen, and sulfur stable isotopes) along a salinity gradient in the San Juan Archipelago, Washington, U.S.A. We tested the hypothesis that freshwater input from riverine discharge would cause significant changes to oceanographic conditions and reduce food quality (indicated by essential fatty acids; EFA), owing to greater contribution of terrestrial organic matter. Contrary to our expectations, availability of high-quality marine-derived POM increased with freshwater input (reduced salinity). Phytoplankton biomass and biomarker composition responded to oceanographic change similarly across tidal and seasonal scales. Using a meta-analysis spanning a range of spatial and temporal scales, we found that chlorophyll a, temperature, dissolved oxygen (DO) and pH were consistently and significantly higher at reduced salinity. The increase of DO and pH corresponding to higher phytoplankton biomass in low salinity water signifies an important feedback of biological activity on seawater chemistry. This analysis supports the use of salinity as an indicator of processes controlling food availability and oceanographic conditions in this region. Collectively, these results highlight the importance of ecosystem connectivity in coastal environments and produce hypotheses for expected changes related to altered river discharge dynamics.

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Broad sampling and diverse biomarkers allow characterization of nearshore particulate organic matter

Cited by 49 publications

References 57 publications

Inferring phytoplankton community composition with a fatty acid mixing model

Inferring phytoplankton community composition with a fatty acid mixing model

Indirect effects of sea otters on rockfish (Sebastes spp.) in giant kelp forests

Improved marine‐derived POM availability and increased pH related to freshwater influence in an inland sea

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