Ocean acidification affects fish spawning but not paternity at CO ₂ seeps

Abstract

Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO 2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO 2 levels. Despite the higher risk of sperm competition found at elevated CO 2 , we also found a trend of lower satellite and sneaker male paternity at elevated CO 2 . Given the importance of fish for food security and ecosystem stability, this study highlights the need for targeted research into the effects of rising CO 2 levels on patterns of reproduction in wild fish.

Living in a high CO2 world: a global meta‐analysis shows multiple trait‐mediated fish responses to ocean acidification

“…As an example, we found that larval growth was significantly reduced at high CO 2 levels and smaller larvae may exhibit a lower performance and survival in the wild as a result of their reduced swimming ability and less efficient predator avoidance (e.g., Miller et al. ), therefore leading to increased mortality through predation. Interestingly, our analysis highlighted that mortality increased for pelagic species and decreased for benthic species at high p CO 2 levels.…”

Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment

“…Surveys of these seep systems have consistently shown that rising carbon dioxide causes species diversity to fall, and they reveal the mechanisms that drive changes in ecosystem function (Sunday et al, 2016). Elevated CO 2 can have direct effects, for example through carbonate dissolution (Rodolfo-Metalpa et al, 2011), benefits to photosynthesis (Cornwall et al, submitted), increased metabolic costs (Garilli et al, 2015) and effects on fish behavior (Milazzo et al, 2016). They can also have indirect effects that drive shifts in coastal systems, such as decreased habitat complexity (Fabricius et al, 2015), altered underwater soundscapes (Rossi et al, 2016) and changes in inter-and intraspecific interactions of every kind (Gaylord et al, 2015;Smith et al, 2016).…”

Ocean acidification alters meiobenthic assemblage composition and organic matter degradation rates in seagrass sediments

“…This study was carried out between April 2014 and July 2015 in shallow P. oceanica meadows at CO 2 vents off the Castello Aragonese isle (Ischia Island, 40°43′51.01″N, 13°57′48.07″E; Tyrrhenian Sea, Italy). Submarine vents have been extensively used to assess the effects of naturally acidified seawater on biological communities as they are characterized by the emission of gases into seawater, predominantly CO 2 , which create gradients in pH and carbonate chemistry, without confounding gradients of other environmental variables, such as temperature, salinity, hydrodynamic conditions, and toxic hydrogen sulfide (Hall‐Spencer et al ; Fabricius et al ; Russell et al ; Milazzo et al ; Doubleday et al ). In particular, in the last decade, previous studies carried out at Ischia Island vents have shown that areas exposed to CO 2 bubbling do not differ from control areas in terms of salinity (38‰), temperature (seasonal fluctuations of 14–25°C), light (~ 7500 lx d −1 ), and total alkalinity (2.5 mequiv.…”