Progressive Deepening in the Depth of Fishing for a Pelagic Fish in the Arabian/Persian Gulf

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Effects of ocean warming on larval development of Patella ordinaria from the Canary Islands

One of the most commonly predicted effects of global ocean warming on marine communities is a poleward shift in the distribution of species with an associated replacement of cold‐water species by warm‐water species. Such predictions are imprecise and based largely on broad correlations in uncontrolled studies that examine changes in species composition and abundance relative to seawater temperature. Before‐After‐Control‐Impact (BACI) analyses of the effects of a large thermal discharge shows that an induced 3.4 deg. C rise in seawater temperature over 10 years along 2 km of rocky coastline resulted in significant community‐wide changes in 150 species of algae and invertebrates relative to controls. Contrary to predictions from biogeographic models, there was no trend towards warm‐water species with southern geographic affinities replacing cold‐species with northern affinities. Instead, communities were greatly altered in apparently cascading responses to changes in abundance of several habitat‐forming taxa, particularly subtidal kelps (e.g. Pterygophora californica) and intertidal foliose red algae (e.g. Mazzaella flaccida). Many temperature sensitive algae decreased greatly in abundance, whereas many invertebrate grazers increased. The results indicate that the responses of temperate reef communities to ocean warming can be strongly coupled to direct effects on habitat‐forming taxa and indirect effects operating through ecological interactions. Given our understanding of temperate reef ecology and its local variability, the results also suggest that accurate predictions of the effects of global ocean warming will be difficult to make.

It is proposed that emissions of volatile sulfur compounds by coral reefs contribute to the formation of a biologically-derived feedback on sea surface temperature (SST) through the formation of marine biogenic aerosol (MBA). The direction and strength of this feedback remains uncertain and constitutes a fundamental constraint on predicting the ability of corals to cope with future ocean warming. We investigate the effects of elevated SST and irradiance on satellite-derived fine-mode aerosol optical depth (AOD) throughout the Great Barrier Reef, Australia (GBR) over an 18-year time period. AOD is positively correlated with SST and irradiance and increases two-fold during spring and summer with high frequency variability. As the influence of non-biogenic and distant aerosol sources are found to be negligible, the results support recent findings that the 2,300 km stretch of coral reefs can be a substantial source of biogenic aerosol and thus, influence local ocean albedo. Importantly however, a tipping point in the coral stress response is identified, whereby thermal stress reaches a point that exceeds the capacity of corals to influence local atmospheric properties. Beyond this point, corals may become more susceptible to permanent damage with increasing stress, with potential implications for mass coral bleaching events.

Coral reefs are constructed of calcium carbonate (CaCO3). Deposition of CaCO3 (calcification) by corals and other reef organisms is controlled by the saturation state of CaCO3 in seawater (Ω) and sea surface temperature (SST). Previous studies have neglected the effects of ocean warming in predicting future coral reef calcification rates. In this study we take into account both these effects by combining empirical relationships between coral calcification rate and Ω and SST with output from a climate model to predict changes in coral reef calcification rates. Our analysis suggests that annual average coral reef calcification rate will increase with future ocean warming and eventually exceed pre‐industrial rates by about 35% by 2100. Our results suggest that present coral reef calcification rates are equivalent to levels in the late 19th century and does not support previous suggestions of large and potentially catastrophic decreases in the future.

Marine phytoplankton play a central role in supporting life in the oceans and profoundly affect global biogeochemical cycles. Previous studies have revealed positive effects of sea‐surface temperature (SST) on phytoplankton in terms of chlorophyll a concentrations (Chla) in high latitude oceans, while negative effects prevail in tropical and midlatitude oceans as well as under stratified summer conditions at higher latitudes. Based on a global analysis of 20 years of ocean Chla and SST data, we first investigated how interannual variability in SST is associated with Chla for each month of the season for every ocean province. We then quantified how the SST‐Chla relationships varied with the long‐term average (baseline) SST. We found significant season‐dependent SST effects on Chla in most ocean provinces. The signs and magnitudes of these effects were consistently associated with the baseline SST, with a shift from positive to negative effects of SST on Chla around 14°C. Based on field observations and literature data, we also estimated the interaction between nitrate limitation and temperature on the SST‐Chla relationship. Our findings suggest that the ocean warming effects on Chla depend consistently on the baseline temperature, both with regard to seasonal effects within regions and regional effects between high and low latitude provinces. Our analysis further suggests that the monthly 14°C isotherms can be used as a first approximation to separate areas and seasons where warming has opposite signed effects.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 473:235-246 (2013) - DOI: https://doi.org/10.3354/meps10058 Effects of ocean warming and acidification on embryos and non-calcifying larvae of the invasive sea star Patiriella regularis Maria Byrne1,*, Maria Gonzalez-Bernat2, Steve Doo3, Shawna Foo3, Natalie Soars3, Miles Lamare2 1Schools of Medical and Biological Sciences, University of Sydney, New South Wales 2006, Australia 2Department of Marine Science, University of Otago, Dunedin, New Zealand 3School of Medical Sciences, University of Sydney, New South Wales 2006, Australia *Email: mbyrne@anatomy.usyd.edu.au ABSTRACT: Little is known about the effects of potential synergies between concurrent ocean warming and acidification on marine benthos. We investigated the effects of warming and acidification on development to the non-calcifying larval stage in the sea star Patiriella regularis, in embryos reared from fertilization in present and future (2100+) conditions. Fertilization using gametes from multiple parents, to represent populations of spawners, was resilient to both stressors, as were cleavage stage embryos. Warming increased developmental rate across all pH levels. For blastulae, there was a complex interaction between stressors, with +4°C/pH 7.6 lethal to many embryos. A 4°C warming increased mortality by the gastrulation stage by 13 to 25% across all pH levels. In conjunction with warming, pH 7.6 increased mortality by 25 to 27% across all temperatures. For embryos that reached the 3 d bipinnaria stage, warming reduced the percentage of normal larvae and larval size, with no effect of acidification. These results highlight the importance of considering both warming and acidification, and effects on early embryos, in assessing life history responses to ocean change. Bipinnaria reared to Day 28 to determine the effects of acidification on non-calcifying feeding larvae provided a comparison with results for calcifying echinoplutei. pH 7.6 resulted in smaller larvae and increased mortality by 30%. After 24 d, near-future ocean acidification levels (pH 7.8) also resulted in smaller larvae. The effects of acidification in reducing growth in larvae that do not calcify indicates that the stunting response of echinoderm feeding larvae to pH/pCO2 is strongly influenced by hypercapnic changes in metabolism and teratogenic effects. The results have implications for P. regularis in its invasive range in Australia, where this species is likely to be deleteriously affected by ocean warming. KEY WORDS: Climate change · Ocean warming · Ocean acidification · Sea star · Non-calcifying larvae · Invasive species Full text in pdf format Supplementary material PreviousNextCite this article as: Byrne M, Gonzalez-Bernat M, Doo S, Foo S, Soars N, Lamare M (2013) Effects of ocean warming and acidification on embryos and non-calcifying larvae of the invasive sea star Patiriella regularis. Mar Ecol Prog Ser 473:235-246. https://doi.org/10.3354/meps10058 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 473. Online publication date: January 21, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod

The central Arctic Ocean is rapidly changing due to amplified warming and sea ice retreat. Nonetheless, it remains challenging to document and decipher impacts on key ecosystem processes such as primary production and pelagic-benthic coupling, due to limited observations in this remote area. Here we investigated environmental changes at the Laptev Sea continental slope (60-3400 m water depth) from the surface to the seafloor, by replicating sample transects two decades apart. Mean break-up of sea ice occurred earlier and mean freeze-up occurred later in 2012 compared to 1993, extending the ice-free period by more than 30 days. On average, observations and model results showed an annual increase in primary production of 30% and more in the study area in 2012. In contrast, calculated and modelled fluxes of particulate organic carbon (POC) to the seafloor were only slightly higher in 2012 and did not extend as far into the deep Laptev Sea as the increase in primary production, possibly due to a more developed retention system. Nevertheless, benthic surveys revealed a substantial increase in phytodetritus availability at the seafloor along the entire transect from the shelf edge to the deep sea. This calls for carbon input by lateral advection from the shelves, additional input from sea ice, and/or a late summer bloom. We also investigated the composition and activity of bacterial communities at the seafloor and potential linkages to the observed environmental changes. While bacterial abundance, biomass and overall community structure showed no systematic differences between the two contrasting years at all depths, extracellular enzymatic activities had increased as a result of higher food availability. This was partly reflected in higher benthic oxygen uptake, indicating a moderate impact on benthic remineralization rates at the time of sampling. Our results show considerable effects of ocean warming and sea ice loss on the ecosystem from the surface ocean to the seafloor in the Laptev Sea, which are likely to continue in the coming decades.

Linking physiological response and toxin transfer: effects of ocean warming on paralytic shellfish toxins in Concholepas concholepas.

Resilience of a harvested gastropod, Turbo militaris, to marine heatwaves

Seasonal variation of zooplankton and pelagic fish catch in the fishing grounds off Tiruchendur coast, Gulf of Mannar, India

Changes in precipitation pattern have been associated with global warming and is of more importance particularly for monsoon dependent regions such as India, which receives maximum rainfall from south-west monsoon. Indian land mass is surrounded by ocean from three sides named Arabian Sea (AS), Bay of Bengal (BOB) and rest of the Indian Ocean (IO) which makes its climate more sensitive. To understand the effect of global warming, long term (1960–2017) annually averaged in-situ sea surface temperature (SST) is studied which shows an increasing trend (~ 0.11 °C/decade; P < 0.05) with higher variations (r2AS = 0.46; r2BOB = 0.43) over AS and BOB whereas comparatively lower in magnitude (~ 0.14 °C/decade; P < 0.05) with less variation (r2IO = 0.74) over IO. Rise in SST could vary evaporation rate, moisture content, cloud temperature and initial conditions required for cloud formation. To understand this heterogeneity in conjunction with seasonal variation, present study correlates cloud microphysical properties such as cloud effective radius (CER) with SST and aerosol optical depth (AOD) at high-resolution (1° × 1°) using linear interpolation method during 2001–2016. Features of north-east monsoon captures with high (~ 0.006–0.012 kg/kg) specific humidity at 850 hPa, positive correlation (~ 0.1–0.8) of SST-CER and negative correlation (~ − 0.1 to ~ − 0.8) of AOD–CER over BOB which may imply formation of bigger droplets due to presence of more moisture and less AOD. Though these patches show prominent results, it also shows scattered interpolation signifying role of other parameters on CER. Findings would be promising with more parameters, which can be used as an input data in climate models to understand regional climate variability.

Global change has generated challenges for oceans, from individuals to the entire ecosystem, and has raised contemporary issues related to ocean conservation and management. Specifically, coral reef ecosystems have been exposed to various environmental and human disturbances. In this study, the Ecopath with Ecosim model was used to explore the impacts of ocean warming and fishing on Xisha Islands coral reef ecosystem in the South China Sea. The variables in this model included two ocean warming scenarios and three fishing scenarios. The model consisted of 23 functional groups including algae, coral, sea birds, and sharks. Our results showed that by the middle of the century, ocean warming and fishing led to a 3.79% and 4.74% decrease in total catch compared with 2009, respectively. In addition, the combined effects of ocean warming and fishing caused a 4.79% decrease in total catch, and the mean trophic level of catch was predicted to decrease by 6.01% under the SSP585-High fishing scenario. Reducing the fishing effort mitigates the effects of ocean warming on some species, such as large carnivorous fish and medium carnivorous fish; however, under low fishing effort, some functional groups, such as small carnivorous and omnivorous fish, have low biomass because of higher predation mortality.

Atmospheric CO2 concentration [CO2] has increased from a pre-industrial level of approximately 280 ppm to approximately 385 ppm, with further increases (700–1000 ppm) anticipated by the end of the twenty-first century [1]. Over the past three decades, changes in [CO2] have increased global average temperatures (approx. 0.2°C decade?1 [2]), with much of the additional energy absorbed by the world's oceans causing a 0.8°C rise in sea surface temperature over the past century. The rapid uptake of heat energy and CO2 by the ocean results in a series of concomitant changes in seawater carbonate chemistry, including reductions in pH and carbonate saturation state, as well as increases in dissolved CO2 and bicarbonate ions [3]: a phenomenon defined as ocean acidification. Time-series and survey measurements [4–6] over the past 20 years have shown that surface ocean pH has reduced by 0.1 pH unit relative to pre-industrial levels, equating to a 26% increase in ocean acidity [3]. Reductions of 0.4–0.5 pH units are projected to occur by the end of the twenty-first century [1] and, while atmospheric [CO2] has consistently fluctuated by 100–200 ppm over the past 800 000 years [7], the recent and anticipated rates of change are unprecedented [8].