Proxy For Water Temperature Research Articles

Sr/Ca in shells of laboratory-grown bivalves (Arctica islandica) serves as a proxy for water temperature – implications for (paleo)environmental research?

Seawater temperature is an essential quantity for paleoclimatological and paleoecological studies. A potential archive that can provide century-long, temporally well-constrained and high-resolution temperature proxy data is available in the form of bivalve shells. However, the number of well-accepted and robust temperature proxies contained in shells is limited to stable oxygen isotopes and carbonate clumped isotopes. Many studies have therefore investigated the possibility to reconstruct temperature from element/Ca properties, specifically Sr/Ca ratios in case of aragonitic shells. As demonstrated here, in agreement with thermodynamic expectations and the lattice strain model, shell Sr/Ca of laboratory-grown Arctica islandica specimens is strongly positively coupled to water temperature. If ultrastructure-related bias is mathematically eliminated, up to 75% of the variability in shell Sr/Ca data can be explained by water temperature. However, in field-grown specimens, this relationship is superimposed by other environmental variables that can hardly be quantified and mathematically eliminated. The explained variability of Sr/Ca is reduced to merely 26% and the prediction uncertainty too large for reliable temperature estimates. Most likely, the equable, less biased conditions in the laboratory resulted in the production of a more uniform shell ultrastructure (with larger and more elongated biomineral units) which in turn was associated with less variable Sr/Ca values and a stronger link to water temperature. Without a detailed understanding and quantification of the factors controlling ultrastructural variations in field-grown bivalves, it remains impossible to employ shell Sr/Ca of wild A. islandica specimens for precise temperature estimates, merely a qualitative temperature reconstruction seems feasible.

In a pinch: Skeletal carbonate mineralogy of crabs (Arthropoda: Crustacea: Decapoda)

Skeletal carbonate mineralogy data from the literature was combined with new X-ray diffractometry data from New Zealand crabs, in order to elucidate mineralogical patterns related to body part, habitat, latitude, and phylogeny, with a view to understanding both the potential vulnerability and the preservation potential of crab shells. In general, crab carbonate is 100% Mg-calcite. In nine specimens from three New Zealand species (Austrohelice crassa, Charybdis japonica, and Hemigrapsus crenulatus) we found the first record of aragonite in brachyurid crab carbonate. Brachyurid crabs tested here generally produce Mg-calcite with mean of 6–7 wt% MgCO3, though families Epaltidae, Majidae, Menippidae and Oziidae produ\\ce high-Mg calcite (8–9 wt% MgCO3), while Eiphiidae and Hymenosomatidae produce low-Mg calcite (3–4 wt% MgCO3). Anomurid crabs showed no aragonite in any specimen, but varied more in Mg content, with the family Porcellanidae producing the highest mean Mg content found (9.3 wt%MgCO3). In most cases the standard deviation and range of values within species is small (SD 0–1.5, range 1–3 wt% MgCO3. There is little evidence of partitioning of Mg in skeletal elements; Mg in the claw, for example, is not significantly different than that of the carapace, legs, or abdomen, whether considered across all species, or within individuals. Latitude (as a proxy for water temperature), too, does not appear to affect Mg in crabs, though it is possible that environment (rocky vs sandy shore) does. The strong tendency for crabs to produce mid-range Mg in calcite suggests that they may be striking a balance between mechanical strengthening of calcite while limiting solubility in sea water.

Morphological variations of crossed-lamellar ultrastructures of Glycymeris bimaculata (Bivalvia) serve as a marine temperature proxy

Bivalve shells are among the most promising archives for high-resolution seawater temperature reconstructions. However, despite major research advances in bivalve sclerochronology over the past decades, estimating water temperature from shells remains a challenging task. This is largely because the most frequently used and widely accepted temperature proxy in bivalves, i.e., the shell oxygen isotope (δ18Oshell) value, also requires knowledge of changes in δ18O of the water (δ18Owater) in which the bivalve lived, which is rarely available for ancient environments. According to a few recent studies, the size and shape of individual biomineral units (BMUs) of the shell ultrastructure may serve as an independent temperature proxy that is also less vulnerable to diagenetic changes than isotope chemical proxies. However, the crossed-lamellar ultrastructure, which occurs in ca. 90% of all mollusk species, has hitherto not been investigated. Here, we evaluate the potential use of morphological properties of the BMUs in Glycymeris bimaculata as a proxy for water temperature. For this purpose we introduce a suitable preparation technique (immersion for 2 m in 0.001 vol% formic acid followed by 20–30 m in 3.5 vol% H2O2) and an automated image processing technique that tremendously speed up ultrastructure analysis (5 s versus one to 2 h image processing time with automated and manual methods, respectively) and increase the robustness of BMU measurements. Glycymeris is a particularly useful target taxon, because it is a cosmopolitan genus with evolutionary roots in the Upper Cretaceous, and some species of Glycymeris can attain a lifespan of more than two hundred years, which allows for long-term, high-resolution paleoclimate reconstructions. As in other previously studied ultrastructures, larger and more elongated BMUs formed in warmer water permitting temperature estimates with an error of 2.3 °C (1 σ). Since the new temperature proxy is unaffected by other environmental variables, including salinity, it can potentially be applied to (modern and fossil) specimens from brackish environments.

Microscale magnesium distribution in shell of the Mediterranean mussel Mytilus galloprovincialis: An example of multiple factors controlling Mg/Ca in biogenic calcite

Since magnesium concentration (Mg/Ca) in biogenic calcite is considered to reflect water temperature during precipitation, the magnesium-to‑calcium ratio has been examined as a proxy for water temperature in paleoclimate research, although factors other than temperature may also influence Mg/Ca in biogenic calcite, thereby introducing a potential bias in the relationship between Mg/Ca and temperature observed in inorganic systems. To better understand factors controlling Mg incorporation into the calcitic shells of bivalves, the distribution of Mg in the Mediterranean mussel Mytilus galloprovincialis was studied, being compared with ambient sea surface temperature (SST), shell growth rate and the distribution of organic matter. Although a positive relationship between Mg/Ca and SST was observed, Mg/Ca had been influenced by additional factors, including the enhancement of Mg incorporation by organic matter, evidenced by the growth line being more Mg-enriched than the growth increments. Furthermore, Mg/Ca was relatively enriched in the undulating (higher curvature) shell portion, being linked to neither SST, growth rate or organic matter. Zoning of Mg2+/Ca2+ within extrapallial fluid at the time of undulating shell portion formation was hypothesized, and heterogeneous Mg distribution in contemporaneously formed shell portions concluded as limiting the usability of Mytilus shell Mg/Ca as a proxy for water temperature.

Smaller size‐at‐age menhaden with coastal warming and fishing intensity

The size‐at‐age of one million Brevoortia tyrannus and B. patronus, harvested from Maine to Texas over 65 years, were analysed to determine if there was evidence of changes consistent with the well documented temperature size rules. The average annual weight and length for age 3‐, 4‐ and 5‐year‐old fish declined on both the Atlantic and Gulf of Mexico (GOM) coasts. For example, the average size of a 4‐year‐old fish captured in 2010 from the Atlantic and GOM, relative to an average 4‐year‐old fish captured in 1987, is 15 per cent and 11 per cent lighter, respectively. Small changes in the year‐to‐year size of same‐aged fish were closely related to variations in the annual air temperature (used as a proxy for water temperature) for fish on both coasts. The size‐at‐age of GOM fish are also smaller during overfished periods compared with underfished periods by 10–24 per cent, and decrease by about the same proportion as indicated by temperature changes. The most plausible explanation for these size changes is that they are a consequence of recent coastal and oceanic warming. These reductions in size‐at‐age by temperature and fishing pressure affect egg production, oil yield and prey community for one‐half of the US Atlantic and GOM fish harvest. The future of menhaden fish size‐at‐age will be, it seems, smaller as oceanic temperatures rise.

Evaluation of oxygen isotope and Mg/Ca ratios in high‐magnesium calcite from benthic foraminifera as a proxy for water temperature

AbstractOxygen isotope ratios (δ18O) and Mg/Ca ratios in organically produced calcium carbonate (calcite and aragonite) by marine species have been used as proxies for paleotemperature. The relationship between the components of large benthic foraminiferal tests (high‐magnesium calcite) and seawater temperature has been little investigated yet. We conducted culture experiments using two species of reef‐dwelling large benthic foraminifera under six temperature conditions (21–30°C). We selected the perforate species Calcarina gaudichaudii, and the imperforate species Amphisorus kudakajimensis, both of which are host to algal symbionts, for the experiments. The results indicated the significant correlation of Mg/Ca ratios (C. gaudichaudii and A. kudakajimensis) and δ18O (C. gaudichaudii) with temperature. The test weight of both species showed temperature dependency, with maxima at 27°C or 29°C and subsequent decline at 30°C. After correction for the contribution of the initial tests, which can be calculated from the weight ratios of the initial and cultured tests, the relationships of the Mg/Ca ratios and δ18O to temperature were obtained with the least squares best fit method as follows: C. gaudichaudii: T = 18.5–4.52 (δ18Oc–δ18Osw), A. kudakajimensis: T = 25.0–4.96 (δ18Oc–δ18Osw), and C. gaudichaudii and A. kudakajimensis: Mg/Ca = 2.85 T + 81.20. We concluded that species‐specific calibration is unnecessary for Mg/Ca‐temperature relationship, although it is necessary for δ18O related to the different calcification mechanisms of imperforate (A. kudakajimensis) and perforate (C. gaudichaudii) species.

Time Series Regression in Aquaculture

Time Series Regression in Aquaculture

Changes of shell microstructural characteristics of Cerastoderma edule (Bivalvia) — A novel proxy for water temperature

Shells of bivalves potentially provide an excellent archive for high-resolution paleoclimate studies. However, quantification of environmental variables, specifically water temperature remains a very challenging task. Here, we explore the possibility to infer water temperature from changes of microstructural characteristics of shells of the common cockle, Cerastoderma edule. The size and elongation of individual microstructural units, i.e., prisms, in the outer shell layer of seven three to five year-old, specimens collected alive from the intertidal zone of the North Sea near Texel, The Netherlands, and Schillig, Germany, were measured by means of automatic image processing. Growth patterns (circatidal, ciralunidian and fortnightly increments and lines), shell oxygen isotope values and mark-and-recovery experiments were used to place the shell record in a precise temporal context. Irrespective of the locality and ontogenetic age, size and elongation of the prisms increased non-linearly with water temperature. Small (0.12±0.05μm2) and round prisms (elongation: 2.42±0.31) were formed at temperatures of ca. 10°C (late April), whereas larger (0.33±0.11μm2) and more elongated prisms (3.26±0.28) occurred during hot summer (ca. 22°C). No clear-cut or consistent correlation existed between microstructural characteristics and growth rate as well as a variety of other environmental variables such as salinity, chlorophyll a and turbidity. Based on these findings, a model was constructed from three shells at Texel that enables reconstruction of water temperature with a precision of 1.7±1.0°C from prism size and elongation: SST= 9.02+17.25 Ps+1.10 Pe. This model was successfully tested at four shells from Schillig. The new temperature proxy can be of particular interest for paleoclimate studies in nearshore settings when non-recrystallized C. edule shells are available. Future studies are required to verify our findings and check if other species with the same and different microstructures show similar relationships with water temperature.

Calibration of the phosphate δ18O thermometer with carbonate–water oxygen isotope fractionation equations

There are significant ambiguities concerning the accuracy of oxygen isotope fractionation equations commonly used to retrieve aquatic paleotemperatures from the δ18O value of phosphatic skeletal remains. This is mainly due to the lack of a certified phosphate standard value, discrepancies in measured standard values between laboratories, and differences in methodologies used to constrain phosphate–water fractionation. Depending on the equation used, differences in calculated isotopic water temperatures may range from 4 to 8°C, these sizable uncertainties significantly reducing the effectiveness of the phosphate 18O/16O ratio as a proxy for water temperature. To address this problem, several phosphate–water fractionation equations from the literature have been tested against the well constrained oxygen isotope fractionation between calcium carbonate and water. Temperatures derived from several pairs of present-day (brachiopods) and fossil (ammonites, brachiopods, belemnite) co-existing carbonate-secreting invertebrates and phosphate-secreting vertebrates (fish) are compared to elucidate the most accurate phosphate-water fractionation equation. These temperatures were obtained by considering using a δ18O value close to 21.7‰ (VSMOW) for the reference phosphorite SRM 120c. The temperature difference (ΔT) calculated from various carbonate–water and phosphate–water oxygen isotope fractionation equations consistently show that the proposed phosphate–water temperature scale established using both modern lingulids and sharks, T(°C)=117.4(±9.5)−4.50(±0.43)∗(δ18OPO4−δ18OH2O), consistently yields temperatures from bioapatites equivalent to those from co-existing carbonates. Compared to other published phosphate-water fractionation equations, this new equation provides the most reliable estimates of aquatic paleotemperatures for bioapatites.

Phylomineralogy of the Coralline red algae: Correlation of skeletal mineralogy with molecular phylogeny

The coralline algae in the orders Corallinales and Sporolithales (subclass Corallinophycidae), with their high degree of mineralogical variability, pose a challenge to projections regarding mineralogy and response to ocean acidification. Here we relate skeletal carbonate mineralogy to a well-established phylogenetic framework and draw inferences about the effects of future changes in sea-water chemistry on these calcified red algae. A collection of 191 coralline algal specimens from New Zealand, representing 13 genera and 28 species, included members of three families: Corallinaceae, Hapalidiaceae, and Sporolithaceae. While most skeletal specimens were entirely calcitic (range: 73-100 wt.% calcite, mean 97 wt.% calcite, std dev=5, n=172), a considerable number contained at least some aragonite. Mg in calcite ranged from 10.5 to 16.4 wt.% MgCO(3), with a mean of 13.1 wt.% MgCO(3) (std dev=1.1, n=172). The genera Mesophyllum and Lithophyllum were especially variable. Growth habit, too, was related to mineralogy: geniculate coralline algae do not generally contain any aragonite. Mg content varied among coralline families: the Corallinaceae had the highest Mg content, followed by the Sporolithaceae and the Hapalidiaceae. Despite the significant differences among families, variation and overlap prevent the use of carbonate mineralogy as a taxonomic character in the coralline algae. Latitude (as a proxy for water temperature) had only a slight relationship to Mg content in coralline algae, contrary to trends observed in other biomineralising taxa. Temperate magnesium calcites, like those produced by coralline algae, are particularly vulnerable to ocean acidification. Changes in biomineralisation or species distribution may occur over the next few decades, particularly to species producing high-Mg calcite, as pH and CO(2) dynamics change in coastal temperate oceans.

Satellite-derived SST data as a proxy for water temperature in nearshore benthic ecology

Satellite-derived sea surface temperatures (SSTs) are increasingly being used as a proxy for water temperature in nearshore marine ecology, but there have been very few evaluations of how accurately SSTs reflect actual temperatures experienced by subtidal organisms. Here, we describe the benthic temperature climatology of 4 coastal locations along a ~1000 km latitudinal gradient in ocean temperature in Western Australia (WA), and compare temperature records from in situ loggers at 10 to 12 m depth with records from 2 independent satellite-derived SST datasets over 2 years. Satellite-derived SSTs were significantly correlated with in situ logger data at all locations, which demonstrate their overall ability to detect general patterns of ecological importance. However, SSTs were also significantly different from benthic water temperatures (usually 1 to 2°C higher), and they did not adequately detect ecologically important small-scale variability or provide reliable informa- tion on temperature extremes. Furthermore, rank orders of the study locations differed between the methodologies, especially in winter. We emphasize the need to carefully consider whether the accu- racy and resolution of satellite-derived SSTs are appropriate for the specific ecological hypothesis being tested in nearshore subtidal habitats, and advocate the use of in situ loggers otherwise. We also highlight the suitability of the WA coastline for experimental work on the effects of temperature (and synergistic factors) on marine organisms.