Publisher: Springer-Verlag (Total: 2626 journals)

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 Marine BiologyJournal Prestige (SJR): 1.085 Citation Impact (citeScore): 2Number of Followers: 63      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1432-1793 - ISSN (Online) 0025-3162 Published by Springer-Verlag  [2626 journals]
• Anemonefish aggressiveness affects the presence of Dascyllus trimaculatus
co-existing with host anemones
• Abstract: Abstract One of the most well-known symbiosis of coral reefs is the relationship between host anemones and anemonefish. Host anemones are used not only by anemonefish but also by other species such as the immature phase of the three spot damsel (Dascyllus trimaculatus). Anemonefish can be a superior competitor to D. trimaculatus, which shares host anemones as shelter resources. Interspecific competition for shelter resources is considered to be an important factor affecting community structure in coral reef fish. In this study, we investigated the factors affecting host anemone utilization of D. trimaculatus around Okinawajima Island. Among 296 colonies, D. trimaculatus inhabited 52 (= 17.6%) host anemones. Decision tree analyses (CHAID) using five independent variables (species of host anemone and anemonefish, presence/absence of adult anemonefish, numbers of immature anemonefish, and size of host anemone) revealed that D. trimaculatus rarely occupied the anemones Entacmaea quadricolor and Stichodactyla haddoni, and seldom cohabited with Amphiprion frenatus and A. polymnus. We experimentally presented a clay model of D. trimaculatus to colonies of six species of anemonefish and compared the duration of aggressive behavior. The aggressive behaviors of A. frenatus and A. polymnus were significantly longer and more intense than that of the other four species. Our findings demonstrate that species composition in anemone symbioses may be affected by coexisting anemonefish as aggressive behavior toward intruders differs among species.
PubDate: 2020-05-30

• Site use and connectivity of female grey seals ( Halichoerus grypus )
around Wales
• Abstract: Abstract Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (Pij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, Pij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, Pij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], Pij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], Pij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, Pij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, Pij = 0.5). While inter-annual fidelity to breeding sites was high (Pij = 0.82–1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.
PubDate: 2020-05-30

• Foraging ecology of masked boobies ( Sula dactylatra ) in the world’s
largest “oceanic desert”
• Abstract: Abstract The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the largest “oceanic desert.” Rapa Nui (Easter Island), located within the South Pacific Gyre, is a breeding ground for masked boobies (Sula dactylatra), which are seabirds with a foraging range that effectively confines them within the gyre. The foraging ecology of this species in the gyre was examined by attaching GPS and time-depth devices to chick-rearing adult birds (9 and 14 birds in 2016 and 2017, respectively) and by collecting regurgitates (18 and 15 samples in 2016 and 2017, respectively). In addition, the birds’ foraging ecology between years was compared. Masked boobies traveled in various directions, dived at unspecific locations, and explored areas < 110 km from the colony. Local environmental conditions were not significantly different between years, and differences in foraging parameters (maximum foraging range, trip duration, and dive depth) were greater among individuals than between years. The foraging characteristics of masked boobies suggest that resources were ephemerally distributed around the colony, with similar abundances across years. Under these conditions, traveling to unspecific locations may increase the area covered and the probability of prey encounter. The spatial and temporal consistencies in environmental conditions explain the uniformity of foraging parameters between years. The ability of masked boobies to exploit ephemerally distributed resources in seascapes like Rapa Nui may help explain its pantropical distribution.
PubDate: 2020-05-30

• Bacterial communities on the gills of bonefish ( Albula vulpes ) in the
Florida Keys and The Bahamas show spatial structure and differential
abundance of disease-associated bacteria
• Abstract: Abstract The Caribbean bonefish species Albula vulpes is an economically important nearshore marine sport fish that has notably declined in the Florida Keys over the past 20–30 years. The reasons for this decline are unclear, although habitat loss, water quality reductions, climate change, and other environmental drivers likely play a role. Infectious disease can also cause precipitous species-specific declines in wildlife populations, but virtually nothing is known about infection in bonefish. We analyzed communities of bacteria on the gills of bonefish from the Florida Keys, where declines are pronounced, and the islands of Eleuthera and Inagua in The Bahamas, where no such declines have been recorded. Bacterial community composition varied significantly among island location (Keys, Eleuthera, Inagua) and among sites within island locations (e.g., tidal creeks, coves, inlets). Seventeen times more bacterial taxa were over-represented in the Florida Keys than in The Bahamas, and several bacterial genera over-represented in the Florida Keys have been linked to environmental contamination and disease (e.g., Corynebacterium; Acholeplasma; Staphylococcus; and Streptococcus). These results show that gill bacterial community signatures may prove useful for investigating bonefish spatial ecology and that communities of microbes on bonefish gills contain differentially abundant and potentially pathogenic bacteria that covary with the overall “health” of the population.
PubDate: 2020-05-30

• Migration of black-naped terns in contrasted cyclonic conditions
• Abstract: Abstract Cyclones are currently increasing in frequency and intensity across the tropical regions, and such changes in cyclonic activity can adversely impact tropical marine ecosystems. To examine the potential effects of these changes on marine migrations, we tracked the annual at-sea distribution of black-naped terns from Okinawa Islands, southwest Japan (26.5° N; 127.9° E). Using light-based geolocation loggers, we compared the migration chronology of six terns between 4 years of contrasted conditions regarding cyclones (regionally called typhoons). Shortly after breeding (30 August ± 13.9 days), the birds undertook their migration across the Philippine Sea to coastal regions of Borneo and Sulawesi Islands, and seemed able to avoid or cross the storm systems. The two birds tracked in years of medium–high typhoon activity (2012–2014) seemed to target a stopover area in the northern Philippines several days after a typhoon hit. By contrast, in 2017, no strong typhoon hit in August and the four study birds showed later departure by 23.8 days, but moved significantly quicker, with little or no stopover. Arrival date at the wintering site was similar among years (1 October ± 3.5 days). Terns thus show remarkable variability in their migration chronology, presumably linked with annual storm frequency. However, the limits to this variability are currently unknown. Further, if individuals respond to environmental cues to time their migration to potentially benefit from lagged optimal feeding conditions en route, it is likely that the increase of back-to-back cyclonic events in the region may reduce the benefits of such a strategy for surface-feeding predators.
PubDate: 2020-05-30

• First in situ observation of Cephalopoda at hadal depths (Octopoda:
Opisthoteuthidae: Grimpoteuthis sp.)
• Abstract: The Cephalopoda are not typically considered characteristic of the benthic fauna at hadal depths (depths exceeding 6000 m), yet occasional open-net trawl samples have implied that they might be present to ~ 8000 m deep. Previous in situ photographic evidence has placed the deepest cephalopod at 5145 m. The discrepancies between the two have meant that the maximum depth for cephalopods has gone unresolved. In this study we report on unequivocal sightings, by HD video lander, of a cephalopod at hadal depths. The demersal cirrate octopod Grimpoteuthis sp. was observed at both 5760 and 6957 m in the Indian Ocean. These observations extend the known maximum depth range for cephalopods by 1812 m and increase the potential benthic habitat available to cephalopods from 75 to 99% of the global seafloor.
PubDate: 2020-05-26

• Ecosystem engineering by different seagrasses in the Caribbean : Editorial
comment on the article "Little giants: A rapidly invading seagrass
alters ecosystem functioning relative to native foundation species"
by Muthukrishnan et al. (2020)
• PubDate: 2020-05-19

• Little giants: a rapidly invading seagrass alters ecosystem functioning
relative to native foundation species
• Abstract: The spread of invasive species is a major component of global ecological change and how and when to manage particular species is a difficult empirical question. Ideally, these decisions should be based on the specific impacts of invading species including both their effects on native competitors and how they may or may not play similar roles in broader ecosystem functioning. Halophila stipulacea is an invasive seagrass currently spreading through the Caribbean, and as seagrasses are foundation species, the effects of invasion have the potential to be particularly far-reaching. To evaluate the impacts of H. stipulacea we quantified spread and potential for displacement of native seagrasses as well as the effects of invasion on multiple ecosystem processes, particularly resource support for higher trophic levels and habitat creation. Long-term monitoring suggested that H. stipulacea likely displaces some native seagrasses (Syringodium filiforme and Halodule wrightii), but not others. Halophila stipulacea had lower N and protein levels and higher C:N ratios than native seagrasses, and as such is a poorer quality resource for consumers. We also observed significantly lower consumption of H. stipulacea than the native S. filiforme but limited differences compared to Thalassia testudinum. We found H. stipulacea created a more nutrient limited environment than T. testudinum and there were significantly distinct invertebrate assemblages in native- and invasive-dominated seagrass beds, but no difference in species richness or invertebrate biomass. These results suggest that the spread of H. stipulacea would impact a variety of ecological processes, potentially restructuring seagrass ecosystems through both direct impacts on environmental conditions (e.g., nutrient availability) and indirect food web interactions.
PubDate: 2020-05-19

• Phylogenetic constraint and phenotypic plasticity in the shell
microstructure of vent and seep pectinodontid limpets
• Abstract: Pectinodontid limpets of the genus Bathyacmaea are endemic to hot vents and cold seeps and exhibit greatly variable shell and radular macro-morphologies, rendering reliable species-level identification challenging. Here, we analyzed shell microstructures of western Pacific vent/seep Bathyacmaea limpets using scanning electron microscopy and Raman spectrophotometry to test its usefulness in providing phylogenetic signals. Bathyacmaea shells comprised of two forms of calcitic microstructure including irregular spherulitic prismatic type-A (ISP type-A) and semi-foliated (SF), as well as the aragonitic crossed lamellar (CL) microstructure. Despite marked differences in macroscopic shell morphologies once leading them to be classified into different species or even genera, six morphotypes of Bathyacmaea nipponica from different chemosynthetic localities and substrates shared an outermost ISP-A layer and alternating layers of SF and CL structures in their outer and inner shell layers. A genetically divergent lineage recovered from the South Chamorro Seamount, however, differed in having a simple three-layered shell composition consisting of ISP-A, SF, and CL structures, in that order, from the outside, and an unusually thin inner shell layer consisting of only CL structure. Moreover, the ratio of aragonite and calcite varied with habitat conditions, with calcite dominating in vents and aragonite dominating in seeps. These results suggest that the shell microstructure of pectinodontids is under phylogenetic constraints and provides useful taxonomic signals, while the mineral polymorphism in aragonite/calcite ratio varies according to environmental factors. Furthermore, microstructures of two ‘species’ from Cretaceous seeps confirmed the same patterns in fossil lineages.
PubDate: 2020-05-06

• Tightly shut: flexible valve margins and microstructural asymmetry in
pterioid bivalves
• Abstract: An organic-rich columnar prismatic outer shell layer, which extends far beyond the underlying nacre, has allowed pterioid bivalves (the pearl oysters and their allies) to develop flexible valve margins, allowing a tight hermetic seal when shut. In some taxa, the microstructural arrangement is known to be asymmetrically developed between the two valves. The asymmetry was surveyed across 29 taxa of pterioids (including representatives of known genera) confirming that it is typically the right valve which has a greater expanse of prism-only shell (and less nacre) and showing that this portion of the right valve has more organic content (more than twice the value in some instances) than the equivalent in the left. A more detailed investigation of prismatic material in Pteria penguin comparing the right and left valves revealed that the right valve flange has a higher density of smaller prisms, each with its organic envelope, and not a greater thickness of the organic envelopes themselves. The flange is also thinner on the right valve and shown here to be very flexible when wet. This allows it to bend against the rigid left valve when the shell is closed. Comparison of this structural asymmetry in the pterioids with five outgroup taxa in the Ostreidae and Pinnidae suggests that clades with the asymmetry have been freed from the constraints of a flattened valve morphology and to develop inequivalved forms.
PubDate: 2020-05-06

• Temporal fluctuations in abundance and size of the giant jellyfish
Nemopilema nomurai medusae in the northern East China Sea, 2006–2017
• Abstract: The abundance and size of the giant jellyfish (Nemopilema nomurai) medusae collected by midwater trawl from 2006 to 2017 in the northern East China Sea (nECS) were investigated. While absent in 2008 and 2011, in other years, medusae were prevalent in June and July, rare in October, and not found from January to May. This seasonality in medusa abundance might be related to the life cycle characteristics of this species, with strobilation occurring near Chinese coast of the nECS from late March to early June but medusae dispersing in oceanic currents or dying by early autumn. Peak abundances in June and July varied from 0 to 62.1 × 106 medusa m−2 in the repeatedly observed area (30°30′ N–31 °N, 124°15′ E–126 °E). These annual fluctuations in medusae abundance in the nECS roughly coincide with patterns in the Sea of Japan (JS) in the autumn, which suggests that monitoring in nECS would be effective in predicting the occurrence of this species in the JS which undergoes massive occurrences of this species. The medusae sizes were comparable in June, but smaller in 2006, 2007, 2009, and 2010 than that in 2012–2017 in July. Hence, the existence of a large annual variation in the size of N. nomurai even in the same area and period was indicated.
PubDate: 2020-05-05

• Different responses of coral and rubble-dwelling coral reef damselfishes
(Family: Pomacentridae) to chemosensory cues from coral reef microhabitats

• Abstract: Coral reef fishes are known to respond to chemical cues in the selection of appropriate microhabitats at settlement. Coral- and non-coral-associated species are likely to respond to different stimuli and the cues may change as larvae settle and become familiar with the reef environment. Here, the chemosensory responses of both late-stage larvae and newly settled juvenile damselfishes to microhabitat odours were tested in Kimbe Bay (PNG), including four obligate coral-dwelling species (Dascyllus melanurus, D. reticulatus, Chrysiptera arnazae and Pomacentrus moluccensis) and four rubble-dwelling species (Pomacentrus adelus, P. simsiang, Chrysiptera cyanea and C. rollandi). Damselfishes were subjected to a series of pair-wise chemosensory choice trials using a two-channel choice flume. The responses by late-stage larvae (pre-settled) to chemical cues from their preferred microhabitat type mirrored those exhibited by recently settled juveniles. All four rubble-dwelling damselfish species exhibited a significant aversion toward chemical cues derived from coral microhabitats, preferring to remain either in the water seeded with chemical cues derived from rubble, or the unseeded (control) water. The obligate coral-dwelling damselfish species tended to avoid rubble and select coral cues when tested against seawater, but unexpectedly, exhibited a neutral response when given a choice between coral and rubble odours. These results indicate that coral and rubble-dwelling damselfish differ in the strength of their attraction to preferred or avoidance of non-preferred microhabitats. Both factors are likely to play a role in settlement choices. Our results indicated that for some species, newly settled juveniles could act as suitable substitutes for testing larval behavioural traits.
PubDate: 2020-05-05

• Environmental drivers of oceanic foraging site fidelity in central place
foragers
• Abstract: Finding food is crucial to the survival and reproductive success of individuals. Fidelity to previous profitable foraging sites may bring benefits to individuals as they can allocate more time to foraging rather than searching for prey. We studied how environmental conditions influence when lactating long-nosed fur seals (Arctocephalus forsteri) adopt a risky (low fidelity) or conservative (high fidelity) foraging strategy at two intra-annual temporal scales when foraging in a highly variable oceanic environment. Core foraging areas (CFAs; n = 534; 30 × 30 km cells) of consecutive foraging trips were obtained from geolocation tracks of 12 females from summer to winter in 2016 (n = 5) and 2017 (n = 7). We used the spatial variability (standard deviation) of CFAs between or among oceanic foraging trips as a proxy for individual foraging site fidelity (IFSF). Over the entire oceanic foraging period (n = 12), IFSF in the latitudinal axis increased with stronger sea-surface temperature gradient (SSTgrad), but decreased with greater SSTgrad and sea-surface height gradient variability. Over a period of two consecutive oceanic foraging trips (n = 66), IFSF decreased with greater SSTgrad variability in the earlier foraging trip. LNFS show evidence that they use IFSF as a strategy to potentially optimise food acquisition, and that this behaviour is influenced by mesoscale oceanographic parameters.
PubDate: 2020-05-05

• Carbon:nitrogen ratio as a proxy for tissue nonpolar lipid content and
condition in black sea bass Centropristis striata along the Middle
Atlantic Bight
• Abstract: Spatial and temporal variability in fish tissue lipid content may reflect resource availability, reproductive or maturity state, or environmental suitability. Here, we analyzed nonpolar (storage) lipid and morphometric condition indices of black sea bass (Centropristis striata) collected from coastal waters of the Northwest Atlantic Ocean from New Jersey to North Carolina, USA. We hypothesized that the elemental ratio of carbon to nitrogen (C:N) within C. striata white muscle and liver tissue would be a robust proxy for nonpolar lipid content (NPLC) and that NPLC would predictably covary with traditional condition indices. Further, we analyzed our NPLC tissue indices to determine how regional and biological patterns in muscle and liver NPLC aligned with traditional condition indices. Our results indicated that muscle tissue NPLC was low compared to liver tissue, and regression analysis revealed strong positive relationships between C:N and NPLC for both tissues (muscle—best fit was linear; liver—best fit was asymptotic nonlinear). Correlations of muscle and liver NPLC with other condition indices were index and region dependent (e.g., a reproductive index was positively correlated with muscle NPLC, but negatively correlated with liver NPLC). Tissue NPLC and standard condition indices differed significantly as a function of region, sex, and fish length, although the patterns were not consistent across the different indices. Our results support the use of muscle and liver C:N values to estimate tissue-specific C. striata NPLC. Further, our results indicate that NPLC indices provide additional insight into C. striata physiological condition and could assist studies examining habitat suitability across large spatial or temporal scales.
PubDate: 2020-05-05

• Physiological and behavioural thermoregulation of juvenile yellowfin tuna
Thunnus albacares in subtropical waters
• Abstract: Fish of the genus Thunnus are unusual because they are regional endotherms. In this study, archival tag data were used to demonstrate behavioural and physiological thermoregulation in juvenile yellowfin tuna, Thunnus albacares (35−52 cm fork length). Tags inserted into the peritoneal cavity were recovered from 23 yellowfin tuna caught mainly around Ishigaki Island, Japan, in 2009−2012. Peritoneal and environmental temperatures and depth data revealed that juvenile yellowfin tuna made daytime bounce dives repeatedly with a median dive duration of 16 min, and they remained at the surface during night-time. Body temperature daily averages were slightly higher than those of ambient temperature, and the body temperatures varied according to ambient temperature changes associated with vertical movements. Heat exchange coefficients (λ) during dives were estimated by a heat budget model. The thermal inertia component of λ was estimated in an experiment with dead juvenile yellowfin tuna. The value of λ exceeded the measured thermal inertia and varied between ascents and descents, thus providing evidence that physiological thermoregulation contributes to λ in juvenile yellowfin tuna and varies according to environmental temperature. Physiological thermoregulation helps maintain relatively stable body temperatures during dives in which tuna behaviourally escape cool deep waters and enter warm surface waters. Comparison of the obtained physiological parameters of λ and heat production (̇$${\dot{T}}_{\mathrm{m}}$$) with those previously recorded in Pacific bluefin tuna indicate that yellowfin tuna has a higher λ and lower $${\dot{T}}_{\mathrm{m}}$$ than Pacific bluefin tuna, which may restrict yellowfin tuna to warm tropical and subtropical surface waters.
PubDate: 2020-05-05

• Resilience of the amphipod Hyale niger and its algal host Sargassum
linearifolium to heatwave conditions
• Abstract: Ocean warming and increasing incidence of marine heatwaves (MHW) challenge the survival of marine organisms. While the impacts of climate scenario-based ocean warming are well investigated, the response of organisms to extreme events such as MHW is less understood. In this study, the thermal tolerance of the amphipod Hyale niger, an ecologically important amphipod in southeast Australia, and its algal host Sargassum linearifolium, were determined. For H. niger, a broad temperature range (2–33 °C) was tested in 6-day exposures in three seasons (summer, autumn and winter) and extended to 11 days in summer. Despite the 7 °C difference in mean habitat temperature across seasons, H. niger had a similar broad thermal optimum (Topt) range with ≥ 90% survival across a 17–20 degree temperature range. The upper lethal temperature with 50% mortality in the 6-day tests was also similar across seasons (LT50 29–30 °C). In 11-day tests in summer, the LT50 was reduced to 26 °C. Cold tolerance of H. niger indicated potential for poleward migration. Sargassum linearifolium had a similar broad thermal tolerance with a 50% reduction in the photosynthetic capacity at 33 °C. Temperature significantly affected survival of H. niger depending on the size and sex. The decrease in the Topt range over time pointed to the deleterious influence of prolonged heatwaves. The broad thermal tolerance of H. niger and S. linearifolium suggests that this important amphipod–host system may be resilient to habitat warming.
PubDate: 2020-05-05

• Genetic insights into recolonization processes of Mediterranean octocorals
• Abstract: Marine ecosystems are strongly impacted by the consequences of human activities, such as habitat destruction or artificialization and climate change. In the Mediterranean Sea, sessile benthic species, and particularly octocorals, have been affected by mass mortality events linked with positive thermal anomalies. The future survival of octocoral populations impacted by global change will depend on their recolonization abilities facing local extirpation or important modification of their habitat. We studied these processes in Mediterranean octocorals in two situations: the colonization of artificial substrates (wrecks) by the red gorgonian Paramuricea clavata, and the recolonization following mortality events in the yellow gorgonian Eunicella cavolini. With microsatellite markers (seven for P. clavata, five for E. cavolini), we analyzed the genetic diversity of populations on artificial substrates and their differentiation from other neighboring populations. For P. clavata the populations on artificial substrates were not or lowly differentiated from the closest populations (1.3–1.6 km) on natural substrates, and showed similar levels of genetic diversity. Artificial substrates can then be considered as an interesting substitute for natural substrates for this species. For E. cavolini we did not detect any variation in diversity or relatedness following recuperation after mortality events. In both cases, our results suggest the input from different populations in the recolonization process, which helps in maintaining the genetic diversity. These results are useful for the management of these species and of associated ecosystems.
PubDate: 2020-05-05

• Production of male hatchlings at a remote South Pacific green sea turtle
rookery: conservation implications in a female-dominated world
• Abstract: Sea turtles have temperature-dependent sex determination, with males being produced at low incubation temperatures and females at high temperatures within the thermal range for embryonic development. In the context of climate change, there are concerns that warming temperatures will lead to an increase in female production. If primary sex ratios are extremely skewed, low male production (and subsequent male availability) may threaten long-term population viability. Heightening these concerns is the fact that female-biased sex ratios are already reported at the majority of sea turtle nesting sites across the world. Here, we describe for the first time primary sex ratios at a remote green sea turtle (Chelonia mydas) nesting site in the South Pacific. Nesting surveys were conducted on Tetiaroa, French Polynesia, between the 2007/2008 and 2018/2019 nesting seasons and revealed a trend of increasing annual nest numbers with large inter-annual fluctuations. We deployed temperature loggers to record incubation conditions and estimated hatchling sex ratios. We recorded low incubation temperatures (mean = 28.5 °C, standard deviation = 0.7 °C) and estimated that currently 54% of all hatchlings produced are male. Low incubation temperatures may be linked to light sand color, shading from vegetation behind beaches and heavy rainfall. Since this site will likely continue to produce males in the future, there is reason for cautious optimism for this population of green sea turtles.
PubDate: 2020-05-01

• High CO 2 and warming affect microzooplankton food web dynamics in a
Baltic Sea summer plankton community
• Abstract: Aquatic ecosystems face a multitude of environmental stressors, including warming and acidification. While warming is expected to have a pronounced effect on plankton communities, many components of the plankton seem fairly robust towards realistic end-of-century acidification conditions. However, interactions of the two stressors and the inclusion of further factors such as nutrient concentration and trophic interactions are expected to change this outcome. We investigated the effects of warming and high CO2 on a nutrient-deplete late summer plankton community from the Kiel Fjord, Baltic Sea, using a mesocosm setup crossing two temperatures with a gradient of CO2. Phytoplankton and microzooplankton (MZP) growth rates as well as biomass, taxonomic composition, and grazing rates of MZP were analysed. We observed effects of high CO2, warming, and their interactions on all measured parameters. The occurrence and direction of the effects were dependent on the phytoplankton or MZP community composition. In addition, the abundance of small-sized phytoplankton was identified as one of the most important factors in shaping the MZP community composition. Overall, our results indicate that an estuarine MZP community used to strong natural fluctuations in CO2 can still be affected by a moderate increase in CO2 if it occurs in combination with warming and during a nutrient-deplete post-bloom situation. This highlights the importance of including trophic interactions and seasonality aspects when assessing climate change effects on marine zooplankton communities.
PubDate: 2020-04-28

• Sound science, not politics, must inform restoration of Florida Bay and
the coral reefs of the Florida Keys
• Abstract: The comment by Julian (2020) criticizes aspects of our paper, “Nitrogen enrichment, altered stoichiometry, and coral reef decline at Looe Key, Florida Keys, USA.” The comment begins by misrepresenting our extensive literature review, while providing no justification for the claim of a “skewed reading.” Julian’s critique focused on methods of data handling, statistics, and spatial awareness, which we demonstrate in every case to be either irrelevant or incorrect. We provide additional supporting data that refute these claims. For example, Julian criticized the removal of data points below the method detection limits (MDLs), but when these points are included, the results do not change. Further, Julian criticized our removal of outliers, but so few points were excluded that it did not change the results of the statistical analyses. Julian also misinterpreted the methods of our correlation and stepwise regression analyses but did not dispute the Kruskal–Wallis tests of our 30-year dataset that revealed significant decadal changes. Julian’s closing paragraph is replete with misinformation and demonstrates a lack of understanding as to how increased freshwater flows associated with Everglades Restoration have led to a worsening of algal blooms and coral decline in the Florida Keys National Marine Sanctuary (FKNMS). This comment represents a smokescreen to confuse the scientific community about the physical connectivity of the Everglades basin and the FKNMS. Past water management policies based on politics, not sound science, have caused irreparable and ongoing environmental damage to sensitive coral reef communities in the FKNMS.
PubDate: 2020-04-21

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