Limnology and Oceanography最新文献

{"title":"A juvenile journey: Using a highly resolved 3D mooring array to investigate the roles of wind and internal tide forcing in across-shore larval transport","authors":"Kelley McBride,&nbsp;Jennifer MacKinnon,&nbsp;Peter J. S. Franks,&nbsp;Jacqueline M. McSweeney,&nbsp;Amy F. Waterhouse,&nbsp;André Palóczy,&nbsp;John Colosi,&nbsp;Jamie MacMahan","doi":"10.1002/lno.12675","DOIUrl":"10.1002/lno.12675","url":null,"abstract":"<p>The across-shore transport of meroplanktonic larvae is predominantly driven by coastal physical processes, resulting in episodic recruitment of benthic species. Historically, due to the sampling challenges associated with resolving these advective mechanisms across the continental shelf, relevant components of larval transport have been difficult to isolate and understand. We use three-dimensional temperature and velocity data from an array of 29 moorings to identify fundamental physical processes that could have generated successful across-shore transport and settlement of meroplankton. The dense spatial and temporal sampling from this array allows us to use Lagrangian particle tracking to estimate the influences of wind conditions and the internal tide on the across-shore transport of planktonic larvae. Settlement was found to be episodic at all depths studied. Above mid-water, modeled larvae were successfully transported onshore by the internal tide during wind relaxations. Surprisingly, abundant pulses of shallow-water larvae were supplied to the coast on occasions when strong, upwelling-favorable winds (&gt; 4 m s⁻¹) drove offshore-flowing surface waters, revealing a complex, potentially topographically influenced flow. These intense upwelling-favorable winds also contributed to subsurface onshore flows that created large pulses of larval settlement in deeper waters (&gt; 20 m). Our analyses from this highly resolved data set provide novel insights into the interactions of physical drivers in creating episodic pulses of coastal larval recruitment.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2364-2376"},"PeriodicalIF":3.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12675","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142142707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nutrient availability influences the thermal response of marine diatoms","authors":"Mengwen Pang,&nbsp;Kailin Liu,&nbsp;Bingzhang Chen,&nbsp;Xiaodong Zhang,&nbsp;Zuyuan Gao,&nbsp;Zhimeng Xu,&nbsp;Yehui Tan,&nbsp;Jing Yang,&nbsp;Hongbin Liu","doi":"10.1002/lno.12671","DOIUrl":"10.1002/lno.12671","url":null,"abstract":"<p>Understanding how phytoplankton growth responds to temperature is critical for forecasting marine productivity in a warming ocean. While previous laboratory studies have shown that phytoplankton thermal traits such as optimal temperature (<i>T</i>_opt) can be affected by nutrient availability, it is unclear whether this can be extrapolated to natural communities. To address this, we tested the impacts of nutrient availability on the thermal responses of two cosmopolitan diatom genera, <i>Pseudo-nitzschia</i> and <i>Leptocylindrus</i>, through a series of in situ manipulation experiments on natural phytoplankton communities. Analysis of the thermal performance curves revealed that nutrient limitation during summer not only limited the growth of these two genera but also reduced their <i>T</i>_opt and the maximum growth rates (<i>μ</i>_max). <i>T</i>_opt was close to or lower than in situ temperature under ambient nutrient conditions, suggesting that further warming may have a detrimental effect on their growth. However, increasing nutrient supply could counteract this by enhancing <i>T</i>_opt and <i>μ</i>_max. To further confirm the interactive effects of nutrients and temperature on diatoms, we analyzed a 20-yr monitoring dataset on <i>Pseudo-nitzschia</i>, <i>Leptocylindrus</i>, and the whole diatom assembly in Hong Kong coastal waters. We found that the abundances of marine diatoms were significantly higher at high temperatures under nutrient-rich environments while relatively low under low nutrient concentrations. Findings on natural diatom cell density align with the growth performance derived from in situ manipulation experiments, suggesting that abundant nutrients bolster marine diatoms in coping with warming. Our results highlight the importance of considering the influence of nutrient availability on thermal response of phytoplankton growth, which sheds light on how marine primary production may change under climate warming.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2318-2331"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12671","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coral mucus promotes the carbon metabolic potency of microorganisms in the coral reef ecosystem","authors":"Xiaoyu Zhang,&nbsp;Keke Cheng,&nbsp;Yuke Qin,&nbsp;Xinyang Li,&nbsp;Zhonghua Cai,&nbsp;Bo Yang,&nbsp;Mui-Choo Jong,&nbsp;Huina Zheng,&nbsp;Baohua Xiao,&nbsp;Jin Zhou","doi":"10.1002/lno.12673","DOIUrl":"10.1002/lno.12673","url":null,"abstract":"<p>Coral mucus, teeming with organic matter, releases nutrients and microorganisms, affecting element cycling and microbial communities in coral reefs. While terrestrial ecosystems exhibit well-studied priming effects from root exudates, the influence of mucus in marine environments, particularly in coral reefs, remains underexplored. We hypothesize that coral mucus, through its nutrients and microbes, stimulates the surrounding microorganisms, regulating carbon metabolism and thus contributing to high coral reef productivity. Initially, natural samples (<i>Acropora pruinosa</i> mucus, seawater, and sediment) were collected for metagenomic assessment of microbial communities and functions. Results showed significant differences in microbial diversity, community structures, co-occurrence modes, and unique functions among mucus, seawater, and sediment. Subsequent laboratory experiments demonstrated mucus's substantial influence on surrounding microorganisms. Analyses, including 16S rRNA sequencing and Eco-plate results, revealed that mucus regulates microbial composition and activities. Quantitative gene-chip analysis showed significant increase in the functional genes related to carbon fixation (e.g., the 3-hydroxypropionate cycle) and degradation (e.g., pectin and hemicellulose hydrolysis) by 55.81% and 65.48%, respectively. Partial least squares path modeling identified mucus nutrients and microbial community composition as key contributors to carbon metabolic potential. This research confirms that mucus acts as a trigger, reshaping microbial profiles around corals and enhancing carbon utilization efficiency, highlighting its essential role in carbon metabolism and the maintenance of high productivity in coral reef ecosystems.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2348-2363"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chain forming diatoms use different strategies to avoid diffusion limited N assimilation","authors":"Rickard Stenow,&nbsp;Malin Olofsson,&nbsp;Martin J. Whitehouse,&nbsp;Helle Ploug","doi":"10.1002/lno.12677","DOIUrl":"10.1002/lno.12677","url":null,"abstract":"&lt;p&gt;Formation of large colonies by phytoplankton is considered a disadvantage during low nutrient and non-turbulent conditions because of diffusion limitation and competition by neighboring cells. This is assumed by diffusion models and not empirical measurements. Here, we measured cell-specific dissolved inorganic carbon (DIC) and nitrate (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt;) assimilation in two chain-forming &lt;i&gt;Skeletonema marinoi&lt;/i&gt; strains by combining secondary ion mass spectrometry with stable isotopic tracer incubations. The pelagic strains were recently germinated from resting stages and thus not adapted to high nutrient regimes of laboratory cultures. During the exponential phase, the cells assimilated excess &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt; relative to DIC. The DIC and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt; assimilation varied with chain length or the position of the cell within chains but did not follow any consistent trend. Solitary cells were rare and did not exceed 6% of all cells. During the nitrogen-limited stationary phase, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt; assimilation was lower than modeled by mass transfer theory at diffusion limitation. &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt; assimilation rates were apparently limited by the biological uptake rate at nitrate concentrations &lt; 0.46 &lt;i&gt;μ&lt;/i&gt;mol L&lt;sup&gt;−1&lt;/sup&gt;. We conclude that &lt;i&gt;S. marinoi&lt;/i&gt; is adapted to high nutrient concentrations and may seldom be diffusion limited in coastal waters with ambient &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;&lt;/math&gt; concentrations &gt; 0.46 &lt;i&gt;μ&lt;/i&gt;mol L&lt;sup&gt;−1&lt;/sup&gt;. These findings contrast those previously reported in larger chain forming diatoms, for example, &lt;i&gt;Chaetoceros&lt;/i&gt;, which appear to circumvent diffusion limitation at low ambient &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;N","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2391-2405"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12677","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gulf Stream intrusion and deep current upwelling drive dynamic patterns of temperature and food supply within cold-water coral reefs","authors":"Jane V. Carrick,&nbsp;Furu Mienis,&nbsp;Erik E. Cordes,&nbsp;Amanda W.J. Demopoulos,&nbsp;Andrew J. Davies","doi":"10.1002/lno.12659","DOIUrl":"10.1002/lno.12659","url":null,"abstract":"<p>One of the most significant features of the Northwest Atlantic, the Gulf Stream influences high magnitude environmental fluctuations in deep habitats across the South Atlantic Bight. Amid this variability, the Blake Plateau harbors extensive reefs formed by cold-water corals that were previously assumed to rely on narrow ranges of temperature, currents, and particulate supply. A benthic lander collected near-bed conditions at the Richardson Reef Complex, a cold-water reef dominated by the scleractinian <i>Desmophyllum pertusum</i> at 830 m within the path of the Gulf Stream. Specific behavior of the Gulf Stream resulted in recurring environmental patterns at depth. During offshore meanders, deep stream components intruded onto the reef and caused rapid (3.74°C per hour) temperature increases up to 10.8°C (&gt; 5°C above the site mean) and increased chlorophyll. Within 2 d of peak temperatures, intrusions were replaced by strong, turbid upwelling currents that rapidly cooled the site to temperature minima (4.13°C). While considerable environmental variability from the Gulf Stream may otherwise implicate a thermally stressful setting for corals, high-temperature events were likely mitigated by their short duration (&lt; 37.4 h) and physical coupling with enhanced organic material. This hypothesis was supported by high-density clustering of <i>D. pertusum</i> occurrences within 50 km around the Gulf Stream's position along the South Atlantic Bight. This suggests that cold-water corals experiencing environmental variability can be sustained by relationships between food supply, temperature, and currents that vary in strength along stochastic time scales, shedding further light on the niche of cold-water corals.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 9","pages":"2193-2210"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nature-based shoreline protection in newly formed tidal marshes is controlled by tidal inundation and sedimentation rate","authors":"Marte M. Stoorvogel,&nbsp;Stijn Temmerman,&nbsp;Lotte Oosterlee,&nbsp;Ken Schoutens,&nbsp;Tom Maris,&nbsp;Johan van de Koppel,&nbsp;Patrick Meire,&nbsp;Tjeerd J. Bouma","doi":"10.1002/lno.12676","DOIUrl":"10.1002/lno.12676","url":null,"abstract":"<p>Many tidal marshes have been lost by past land use changes, but are nowadays increasingly restored and created to provide valuable ecosystem services such as nature-based flood and erosion protection along estuarine shorelines. To be functional for flood and shoreline erosion protection, restored and created tidal marshes should develop erosion resistant sediment beds. Here, we investigated which factors drive the spatial variations in sediment strength and erosion resistance in a developing tidal marsh restoration site. Our results show that decreasing tidal inundation frequency, decreasing sedimentation rate, and better drainage led to stronger consolidation in deeper sediment layers. This consolidation resulted in greater sediment strength, quantified here by shear strength and penetration resistance. Generally, sediment strength was greater when sediment had higher bulk density, while a higher water and fine fraction (= clay and silt) content decreased sediment strength. Overall, all measurement locations were relatively erosion resistant, likely caused by the dense root network and cohesive sediment. To restore or create resilient tidal marshes for nature-based flood and shoreline erosion protection, we should thus aim for sites with relatively low tidal inundation frequency, moderate sedimentation rates, and cohesive sediment mixtures of clay, silt, and sand, which are well drained and have potential for vegetation establishment. These conditions have a high likelihood of resulting in restored or created tidal marshes that contribute to nature-based flood and shoreline erosion protection.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2377-2390"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12676","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Divergent metabolism estimates from dissolved oxygen and inorganic carbon: Implications for river carbon cycling","authors":"Qipei Shangguan,&nbsp;Robert A. Payn,&nbsp;Robert O. Hall Jr,&nbsp;Fischer L. Young,&nbsp;H. Maurice Valett,&nbsp;Michael D. DeGrandpre","doi":"10.1002/lno.12666","DOIUrl":"10.1002/lno.12666","url":null,"abstract":"<p>Rivers efficiently collect, process, and transport terrestrial-derived carbon. River ecosystem metabolism is the primary mechanism for processing carbon. Diel cycles of dissolved oxygen (DO) have been used for decades to infer river ecosystem metabolic rates, which are routinely used to predict metabolism of carbon dioxide (CO₂) with uncertainties of the assumed stoichiometry ranging by a factor of 4. Dissolved inorganic carbon (DIC) has been less used to directly infer metabolism because it is more difficult to quantify, involves the complexity of inorganic carbon speciation, and as shown in this study, likely requires a two-station approach. Here, we developed DIC metabolism models using single- and two-station approaches. We compared metabolism estimates based on simultaneous DO and DIC monitoring in the Upper Clark Fork River (USA), which also allowed us to estimate ecosystem-level photosynthetic and respiratory quotients (PQ_E and RQ_E). We observed that metabolism estimates from DIC varied more between single- and two-station approaches than estimates from DO. Due to carbonate buffering, CO₂ is slower to equilibrate with the atmosphere compared to DO, likely incorporating a longer distance of upstream heterogeneity. Reach-averaged PQ_E ranged from 1.5 to 2.0, while RQ_E ranged from 0.8 to 1.5. Gross primary production from DO was larger than that from DIC, as was net ecosystem production by <span></span><math>\u0000 <mrow>\u0000 <mn>100</mn>\u0000 <mspace></mspace>\u0000 <mtext>mmol</mtext>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>d</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow></math>. The river was autotrophic based on DO but heterotrophic based on DIC, complicating our understanding of how metabolism regulated CO₂ production. We suggest future studies simultaneously model metabolism from DO and DIC to understand carbon processing in rivers.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 9","pages":"2211-2228"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12666","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increase in marginal sea alkalinity may impact air–sea carbon dioxide exchange and buffer acidification","authors":"Luiz C. Cotovicz Jr.,&nbsp;Bronwyn Cahill,&nbsp;Bita Sabbaghzadeh,&nbsp;Jannine M. Lencina-Avila,&nbsp;Gregor Rehder","doi":"10.1002/lno.12672","DOIUrl":"10.1002/lno.12672","url":null,"abstract":"<p>Total alkalinity (TA) has increased in the Baltic Sea, with implications for atmospheric CO₂-induced acidification and CO₂ uptake. We compiled extensive data of TA in surface waters of the Baltic Sea, aiming to (i) identify new tendencies in the relationship between TA and salinity (TA–S relationship), (ii) update the TA trend analysis, (iii) investigate spatial–temporal patterns, and (iv) discuss potential drivers and implications. We observed a progressive decrease in the slopes and increase in the intercepts of the TA–S overtime due to the persistent process of TA enhancement. A weak seasonal pattern was identified, with warmer months presenting lower salinity and TA. Lower rates of TA increase were observed in high salinities (Skagerrak–Kattegat; +1.00 to +2.20 <i>μ</i>mol kg⁻¹ yr⁻¹), intermediate trends in low salinities (Gulf of Bothnia; +3.28 to +3.57 <i>μ</i>mol kg⁻¹ yr⁻¹), and maximal trends in the Central Baltic Sea (+3.70 to +4.57 <i>μ</i>mol kg⁻¹ yr⁻¹) and Bornholm Basin (+4.82 to +5.32 <i>μ</i>mol kg⁻¹ yr⁻¹). The increase in the intercept of the TA–S in the Gulf of Bothnia suggests a progressive increase in the external supply of TA, although lower than previously thought. The maximum trend in the Bornholm Basin suggests an increase in external supply from the Southern catchment and/or the accumulation of internal production. The positive TA–phosphorus correlations underscore a significant internal source. The TA increase amplifies the CO₂ uptake by 1.8–7.8% during spring/summer and reduces the CO₂ outgassing by 3.4–7.7% in autumn/winter. The TA enhancement has the potential to buffer CO₂-induced acidification by 39–60% by 2050.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2332-2347"},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12672","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small wetland-fringed estuaries deliver disproportionately large carbon loads to the ocean","authors":"Gloria M. S. Reithmaier,&nbsp;Damien T. Maher,&nbsp;Ceylena Holloway,&nbsp;Rogger E. Correa,&nbsp;Isaac R. Santos","doi":"10.1002/lno.12660","DOIUrl":"10.1002/lno.12660","url":null,"abstract":"<p>Previous estimates of dissolved carbon export from estuaries focused on larger systems in the Northern Hemisphere, with little data for smaller tropical estuaries often fringed by intertidal wetlands. We investigated lateral export (outwelling) and transformation rates of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and total alkalinity (TA) as well as CO₂ emissions from 18 diverse Australian estuaries. Most estuaries acted as net sources for DOC (72%), DIC (83%), and TA (50%). On average, estuaries exported 120 ± 55 and 344 ± 150 mmol m⁻² catchment yr⁻¹ DOC and DIC, respectively. Estuarine CO₂ emissions (33 ± 20 mmol m⁻² estuary d⁻¹) equalled 13% ± 16% of the dissolved lateral carbon export. Carbon export positively correlated with runoff, rain, and intertidal wetland cover, and negatively correlated with estuary and catchment area. Mangroves and saltmarshes cover &lt; 1% of all catchments but can contribute 46% ± 11% of the DOC and 67% ± 13% of the DIC exported to the ocean. Upscaling our observations, Australian estuaries export 2.8 ± 2.2 TgC yr⁻¹ DOC, 8.1 ± 6.2 TgC yr⁻¹ DIC, and 0.7 ± 0.6 Tmol yr⁻¹ TA. Small catchments (&lt; 10 ha) making up 70% of all estuaries and accounting for 18% of the total freshwater flow provided 27% to the total dissolved carbon export. Overall, small tropical estuaries fringed by highly productive intertidal wetlands are hotspots of carbon exports and should be considered in marine carbon budgets.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 9","pages":"2229-2242"},"PeriodicalIF":3.8,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12660","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142090109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microplastics may reduce the efficiency of the biological carbon pump by decreasing the settling velocity and carbon content of marine snow","authors":"Cordelia Roberts,&nbsp;Clara M. Flintrop,&nbsp;Alexander Khachikyan,&nbsp;Jana Milucka,&nbsp;Colin B. Munn,&nbsp;Morten H. Iversen","doi":"10.1002/lno.12615","DOIUrl":"10.1002/lno.12615","url":null,"abstract":"<p>Plastics are pervasive in marine ecosystems and ubiquitous in both shallow and deep oceans. Microfibers, among other microplastics, accumulate in deep-sea sediments at concentrations up to four orders of magnitude higher than in surface waters. This is at odds with the fact that most microfibers are positively buoyant; therefore, it is hypothesized that settling aggregates are vectors for the downward transport of microfibers in the ocean. However, little is known about the impact of microfibers on carbon export. We formed diatom aggregates with differing concentrations of microfibers using roller tanks and observed that microfiber addition stimulated aggregate formation, but decreased their structural cohesion and caused them to break apart more readily, resulting in smaller average sizes. The incorporation of positively buoyant microfibers into settling aggregates reduced their size-specific sinking velocities proportional to the microfiber concentration. Slower sinking may extend aggregate retention time in the upper ocean, thereby increasing the time available for organic matter remineralization in the upper water column. Here, we show that at concentrations of 10⁵ microfibers per cubic meter, microfiber incorporation into settling marine aggregates decreases potential export flux by 8–45%. Microfibers accumulating at such high concentrations, for example, in Arctic sea ice, may, therefore, be substantially reducing the efficiency of the biological carbon pump relative to the pre-plastic era.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 9","pages":"1918-1928"},"PeriodicalIF":3.8,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12615","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142085226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}