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Figure 3 in Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Figure 3: Photographic documentation of Laminaria digitata and Hedophyllum nigripes sporophytes exposed to a temperature gradient after post-cultivation at 10 °C. Images are not to scale. Triangular cuts marked individual sporophytes per replicate.

Figure 2 in Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Figure 2: Relative growth rates (RGR; % d−1) of Laminaria digitata (top) and Hedophyllum nigripes (bottom) sporophytes in a temperature gradient over the experimental time (14 days; left side of the dotted line) and recovery at 10 °C (one week; right side of the dotted line; n = 5, mean ± SD). Each value denotes the RGR between the indicated time point and the measuring day before.

Figure 1 in Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Figure 1: Standardized growth rates (GR) based on surface area (%) of Laminaria digitata (white dots) and Hedophyllum nigripes (black dots) sporophytes over two weeks in a temperature gradient (n = 5, mean ± SD). Different letters denote significant differences within each species (ANOVA with Tukey's post hoc test: α <0.05, A– D = L. digitata; a–c = H. nigripes). Asterisks indicate significant differences between standardized GR of L. digitata and H. nigripes (two-way ANOVA with Tukey's post hoc test).

Figure 5 in Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic

Figure 5: Density of gametophytes of Laminaria digitata (A, C) and Hedophyllum nigripes (B, D) at day 7 (A, B) and day 14 (C, D) in temperature gradients between 0 and 25 °C (L. digitata) and 22 °C (H. nigripes) (n = 3–4, mean ± SD). Broken horizontal lines show the mean initial gametophyte density for each species after the acclimatization phase (day 0). †All gametophytes died.

Fig. 12 in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 12. Comparison of the relationships between relative length of hepatic lobe (Hpl/PoL) against postrostral carapace length (PCL) among P. quadridens (De Haan, 1837), P. ferox Ohtsuchi and Kawamura, 2019, and P. longipes n. sp. (modified after Ohtsuchi and Kawamura 2019: fig. 39).

Fig. 8. First ambulatory legs. A–C, Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 8. First ambulatory legs. A–C, Pugettia longipes n. sp., holotype, full-grown male (MBM 188862), 17.3×13.0 mm, Shandong, North China; D, P. ferox Ohtsuchi and Kawamura, 2019, holotype, full-grown male (NSMT-Cr 26069), 40.0×32.1 mm, Otsuchi Bay, Japan; E, P. quadridens (De Haan, 1837), full-grown male (NSMT-Cr 26059), 27.3×22.4 mm, Miura Peninsula, Japan. A, D, E, right first ambulatory legs (P2), general appearance (upper surface); B, carpus (extensor surface); C, right second ambulatory leg (P3), general appearance (upper surface).

Fig. 6. Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 6. Pugettia longipes n. sp. holotype, male (MBM 188862), 17.3×13.0 mm, Shandong, Northeast China. A–C, carpus of right cheliped, dorsal (A), extensor (B), and ventral (C) views, respectively; D–G, merus of right cheliped, inner (D), dorsal (E), outer (F), and ventral (G) views, respectively.

Fig. 5. Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 5. Pugettia longipes n. sp. A, thoracic sternites 1–4; B, male pleon and sternites; C, female sterno-pleonal cavity; D, E, female gonopore (left) in allotype (D) and paratype (E); F, third maxilliped (left). A, B, paratype, full-grown male (MBM 188864), 12.9×9.3 mm; C, D, allotype, full-grown female (MBM 188863), 15.1×10.7 mm; E, paratype, full-grown female (MBM 188866), 18.3×13.7 mm; F, holotype, fullgrown male (MBM 188862), 17.3×13.0 mm.

Fig. 11. Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 11. Pugettia longipes n. sp. allotype, female (MBM 188862), 15.1×10.7 mm, Shandong, North China. A, ventral view; B, dorsal view.

Fig. 1. Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 1. Pugettia longipes n. sp. holotype male (MBM 188862), 17.3×13.0 mm, Shandong, Northeast China. A, ventral view; B, dorsal view.

Fig. 7 in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 7. Left chela in outer view. A–C, Pugettia longipes n. sp.: A, holotype, full-grown male (MBM 188862), 17.3×13.0 mm, Shandong, North China; B, paratype, adolescent male (MBM 188864), 14.1×10.2 mm, same locality; C, allotype, full-grown female (MBM 188863), 15.1×10.7 mm, same locality; D–F, P. ferox Ohtsuchi and Kawamura, 2019: D, holotype, full-grown male (NSMT-Cr 26069), 40.0×32.1 mm, Otsuchi Bay, Japan; E, adolescent male (RUMF-ZC 4981), 31.5×25.8 mm, Akkeshi Bay, Hokkaido; F, allotype, full-grown female (NSMT- Cr 26070), 27.9×22.6 mm, Otsuchi Bay; G–I, P. quadridens (De Haan, 1837): G, full-grown male (NSMT-Cr 26062), 27.4×23.3 mm, Miura Peninsula; H, adolescent male (NSMT-Cr 26064), 18.5×14.2 mm, Boso Peninsula; I, full-grown female (NSMT-Cr 26060), 21.8×18.2 mm, Miura Peninsula.

Fig. 10. Pugettia longipes n in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 10. Pugettia longipes n. sp., individual variations. A, adolescent male (MBM 188867), 13.6×9.3 mm; B, paratype, adolescent male (MBM 188864), 14.1×10.2 mm; C, paratype, full-grown male (MBM 188864), 13.9×10.2 mm, right P5 regenerating; D, paratype, full-grown female (MBM 188866), 13.8×10.3 mm, right first ambulatory leg (P2) regenerating. All the specimens are collected from Shandong, North China.

Fig. 13 in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 13. Proportional length of the cheliped (P1) and ambulatory legs (P2–5) meri in Pugettia longipes n. sp., P. ferox Ohtsuchi and Kawamura, 2019, and P. quadridens (De Haan, 1837). A, fullgrown males; B, adolescent males; C, full-grown females. Bars with different letters are significantly different (Tukey HSD test, otherwise Steel-Dwass test, p<0.01) from each other. See Table 1 for sample numbers. In some groups marked with an asterisk, the significance of differences among the three species were not tested statistically due to small sample number (n<3) of P. longipes n. sp.

Fig. 3 in A New Kelp Crab Species of the Genus Pugettia (Crustacea: Decapoda: Brachyura: Epialtidae) from Shandong Peninsula, Northeast China

Fig. 3. Comparison of frontal view of carapace. A, Pugettia longipes n. sp., holotype, male (MBM 188862), 17.3×13.0 mm, Shandong, Northeast China; B, P. ferox Ohtsuchi and Kawamura, 2019, paratype, male (NSMT-Cr 26071), 30.7×26.3 mm, Akkeshi, Hokkaido; C, P. quadridens (De Haan, 1837), male (NSMT-Cr 26059), 27.3×22.4 mm, Miura Peninsula, Sagami Bay.

opencc-zeroJul 2022View details →

Climate-driven shifts in kelp forest composition reduce carbon sequestration potential

The potential contribution of kelp forests to blue carbon sinks is currently of great interest but interspecific variance has received no attention. In the temperate Northeast Atlantic, kelp forest composition is changing due to climate-driven poleward range shifts of cold temperate Laminaria digitata and L. hyperborea and warm temperate L. ochroleuca. To understand how this might affect the carbon sequestration potential of this ecosystem, we quantified interspecific differences in carbon export and decomposition alongside changes in detrital photosynthesis and biochemistry. We found that while warm temperate kelp exports up to 71% more carbon per plant, it decomposes up to 155% faster than its boreal congeners. Elemental stoichiometry and polyphenolic content cannot fully explain faster carbon turnover, which may be attributable to contrasting tissue toughness or unknown biochemical and structural defences. Faster decomposition causes the detrital photosynthetic apparatus of L. ochroleuca to be overwhelmed 20 d after export and lose integrity after 36 d, while detritus of cold temperate species maintains carbon assimilation. Depending on the photoenvironment, detrital photosynthesis could further exacerbate interspecific differences in decomposition via a potential positive feedback loop. Through compositional change such as the predicted prevalence of L. ochroleuca, ocean warming may therefore reduce the carbon sequestration potential of such temperate marine forests.

opencc-zeroSep 2022View details →

Using Unoccupied Aerial Vehicles (UAVs) to map and monitor changes in emergent kelp canopy after an ecological regime shift

Kelp forests are complex underwater habitats that form the foundation of many nearshore marine environments and provide valuable services for coastal communities. Despite their ecological and economic importance, increasingly severe stressors have resulted in declines in kelp abundance in many regions over the past few decades, including the North Coast of California, USA. Given the significant and sustained loss of kelp in this region, management intervention is likely a necessary tool to reset the ecosystem and geospatial data on kelp dynamics are needed to strategically implement restoration projects. Because canopy-forming kelp forests are distinguishable in aerial imagery, remote sensing is an important tool for documenting changes in canopy area and abundance to meet these data needs. We used small unoccupied aerial vehicles (UAVs) to survey emergent kelp canopy in priority sites along the North Coast in 2019 and 2020 to fill a key data gap for kelp restoration practitioners working at local scales. With over 4,300 hectares surveyed between 2019 and 2020, these surveys represent the two largest marine resource-focused UAV surveys conducted in California to our knowledge. We present remote sensing methods using UAVs and a repeatable workflow for conducting consistent surveys, creating orthomosaics, georeferencing data, classifying emergent kelp, and creating kelp canopy maps that can be used to assess trends in kelp canopy dynamics over space and time. We illustrate the impacts of spatial resolution on emergent kelp canopy classification between different sensors to help practitioners decide which data stream to select when asking restoration and management questions at varying spatial scales. Our results suggest that high spatial resolution data of emergent kelp canopy from UAVs have the potential to advance strategic kelp restoration and adaptive management.

opencc-by-4.0Jan 2024View details →

Data and code to accompany sugar kelp DEB thermal response manuscript

Data and R code to accompany the manuscript "Improving growth models of cultivated sugar kelp (Saccharina latissima) by accounting for intraspecific variation in thermal tolerance" (Krasnow et al., 2024), published in the Journal of the World Aquaculture Society. Some material was originally created by Celeste Venolia in March 2018-December 2019 for <a href="https://doi.org/10.1016/j.ecolmodel.2020.109151">Venolia et al. (2020)</a>. <ul> <li>cold_validation.R contains the code to validate DEB kelp model against data from Trømso, Norway</li> <li>venolia_validation.R contains the code to validate the model against the data from Rhode Island, USA, reproducing the analysis from the original paper and producing new estimates with the newly-estimated temperature parameters</li> <li>SolveR_R.R includes the function that is used to solve for the specific growth rate (r)</li> <li>KelpDEB_model.R includes the deSolve-structured function used to run the model</li> </ul> Please use the most recent version (3.1) so that all data/code needed to run the analyses are present.

opencc-zeroJun 2024View details →

Historical kelp forests in California over multiple centuries

Kelp forests have deteriorated globally due to anthropogenic stressors. There is an urgent need to extend baselines, to understand the processes that underlie the persistence and recovery of kelp forests, and to distinguish the normal range of ecosystem variability from more extreme changes. Using a mixed-method, historical ecology approach we integrate archival data, oral histories, and contemporary ecological data to examine the dynamics of kelp forests over a multi-decadal to multi-century time period in central California. We focus on sea otters, sunflower seastars, sea urchins, kelp cover, kelp species dynamics, and climate. From 1826 to 2020 kelp was highly variable. There were seven periods of low kelp cover and two periods of exceptionally low kelp cover (1896-1899; 2014-2016) following El Niño-Southern Oscillations (ENSOs). Exceptionally low kelp cover did not occur when two predators – seastars and sea otters – were present. In all cases, kelp recovered following times of extremely low cover, with a lag, which was extended by the duration of warm water anomalies. We present the concept of an ENSO Recovery Lag - a metric indicating the time it takes for kelp to recover following ENSO events. Kelp remained low for approximately two years following 80% of ENSOs. The greatest kelp decline (12-fold) was in Santa Cruz (northern Monterey Bay). Herbivore populations (sea urchins) were highly variable over the past century and exhibited short and long-term changes in abundance. Sunflower seastars were present in low, stable abundances prior to seastar wasting disease (1938-2013 mean density: 0.02/m2) when they declined by 97.5%. Insights from this reconstruction indicate that kelp recovery following extended warm water anomalies exhibits a lag, and occurs over multiple years.

opencc-zeroFeb 2023View details →

Sunflower sea star predation on urchins can facilitate kelp forest recovery

The recent collapse of predatory sunflower sea stars (Pycnopodia helianthoides) due to sea star wasting disease (SSWD) is hypothesized to have contributed to proliferation of sea urchin barrens and losses of kelp forests on the North American West Coast. We used experiments and a model to test whether restored Pycnopodia populations may help recover kelp forests through their consumption of nutritionally poor purple sea urchins (Strongylocentrotus purpuratus) typical of barrens. Pycnopodia consumed 0.68 S. purpuratus day−1, and our model and sensitivity analysis shows that the magnitude of recent Pycnopodia declines is consistent with urchin proliferation after modest sea urchin recruitment, and even small Pycnopodia recoveries could generally lead to lower densities of sea urchins that are consistent with kelp-urchin coexistence. Pycnopodia seem unable to chemically distinguish starved from fed urchins and indeed have higher predation rates on starved urchins due to shorter handling times. These results highlight the importance of Pycnopodia in regulating purple sea urchin populations and maintaining healthy kelp forests through top-down control. The recovery of this important predator to densities commonly found prior to SSWD, whether through natural means or human-assisted reintroductions, may therefore be a key step in kelp forest restoration at ecologically significant scales.