Biology of Evechinus chloroticus (echinoidea: Echinometridae) from different localities

Mean gonad indices of Evechinus chloroticus (Val.) at Kaikoura and Kaiteriteri, South Island, New Zealand, increased during the winter and spring to reach peak values during the summer and then decreased to minimum values in autumn. There was only one major summer peak at Kaikoura, but two at Kaiteriteri. The maximum mean gonad index of Kaiteriteri specimens was little higher than the minimum at Kaikoura. Absolute size of gonads and spawn producton were also lower at Kaiteriteri, perhaps because of less food there.

At both localities gametogenic cycles were correlated with gonad index cycles, progressing from unripe to ripe from late autumn to spring, but Kaikoura urchins held ripe gametes over a longer period than Kaiteriteri urchins. The volume of spawn from females was greater than that from males but males had ripe gametes (and could be artificially induced to spawn) longer. At Kaikoura, some spawning probably occurred throughout summer with a major spawning in late summer or early autumn. Large urchins with small dark gonads were found throughout the year, particularly at Kaiteriteri; these were probably senile individuals.

Although at both localities Evechinus matured at 3–4 years, Kaikoura urchins were larger at maturity.

At Kaiteriteri sex ratios of mature Evechinus did not differ significantly from 1:1, but in some populations at Kaikoura males were significantly more prevalent than females.     

Biology of evechinus chloroticus (Echinoidia: Echinometridae) from different localities

Growth bands were demonstrated in the apical plates of Evechinus chloroticus by grinding horizontal sections which were air dried for several days and treated with lactophenol + 0.5% ferrous ions for a few minutes. Only one dark band was formed each year, during summer.

Evechinus grew considerably faster at Kaikoura than at Kaiteriteri, about 2 cm and 1 cm a year respectively, until growth slowed with increasing age. These differences may relate to food availability.

Numbers in year classes varied considerably, and in some Evechinus populations year classes were absent. Most urchins at Kaiteriteri were less than 6 + years old, but urchins up to 10 years old were aged at Kaikoura. More old urchins were found in deeper populations at Kaikoura, where a number may have been up to 15 years old.

Size‐frequency distributions varied markedly among populations. Distributions appear most influenced by recruitment intensity, and higher growth rates and greater longevity were found in populations with predominantly large urchins, as at Kaikoura.     

Variation in sunscreen compounds (mycosporine‐like amino acids) for marine species along a gradient of ultraviolet radiation transmission within doubtful sound,New Zealand

We examined the response of four species of New Zealand marine algae (Ecklonia radiata, Apophlaea lyallii, Rhodymenia spp., Ulva lactuca) and a sea urchin (Evechinus chloroticus) to spatial variation in ultraviolet radiation (UV‐R) by examining the concentration of UV‐R absorbing compounds known as mycosporine‐like amino acids (MAAs). The purpose was to understand how, and the degree to which, local marine species could potentially respond to any future increases in incident UV‐R in the New Zealand marine environment. The research was undertaken in Doubtful Sound, where we observed a gradient of water column UV‐R transmission along the 40 km length of the fiord. We examined spatial differences in MAAs along the UV‐B gradient in the macrophytes and temporal changes in MAAs in sea urchin gonads. Among the algae, thallus MAA concentrations (nmol mg^–1 protein) ranged from 12.5 to 87.8 in E. radiata, from 433.1 to 1446.4 in A. lyallii, 12.7 to 103.4 in Rhodymenia spp., but were not detected in U. lactuca. For E. chloroticus, gonadal MAA concentrations ranged from 83.9 to 224.3 nmol mg^–1 protein spatially, and over the year from 1.85 to 14.12 nmol mg^–1 dry weight (DW) depending on site and gametogenic cycle. Laboratory manipulations indicated that concentrations of MAAs in E. chloroticus gonads and eggs are influenced by diet. MAA concentration could be correlated with UV‐B intensities in two of the algal species. E. chloroticus MAA concentrations could also be correlated with UV‐B transmission, which we concluded was a reflection of the greater ingestion and accumulation of MAA‐rich macrophytes at those sites where higher ambient UV‐R induced greater MAA concentrations to occur in the algae. Given this, we suggest that one response of marine species to increases in UV‐B would be an increase in the synthesis and/or accumulation of MAAs for photoautotrophs and a dietary accumulation of those MAAs in E. chloroticus, an important herbivore in this system.     

Respiration rates of some New Zealand echinoderms (note)

Respiratory rates were measured in four common New Zealand echinoderms, Evechinus chloroticus and Goniocidaris umbraculum (Echinoidea), and Coscinasterias calamaria and Pentagonaster pulcheilus (Asteroidea). Oxygen uptake was monitored with a polarographic oxygen electrode. The respiratory rates at 12°c ranged from 3.8 to 9.8 μl O_2.h^‐1.g^‐1 (live weight). The rates for Evechinus and Coscinasterias fall well within the range of metabolic rates of other echinoids and asteroids. Goniocidaris and Pentagonaster have relatively low respiratory rates.     

Effects of sea urchin (Evechinus chloroticus) grazing in Dusky Sound,Fiordland, New Zealand

Evechinus chloroticus (Val.) is known to be an important grazer of subtidal barren habitats in northern New Zealand but its role in structuring rocky reef communities at colder southern localities is poorly understood. The present study was prompted by a proposal for the establishment of an E. chloroticus fishery in Dusky Sound, Fiordland, New Zealand. To determine the ecological importance of E. chloroticus in Dusky Sound, sea urchins were experimentally removed from shallow fucoid fringe (upper zone), mid‐depth barrens (middle zone), and deeper algal meadow (lower zone), at eight sites and compared with a paired set of eight control sites. Two years of continuous removal of E. chloroticus resulted in conspicuous changes to the algal community at all depth zones examined. The density of fucoid algae (Carpophyllum spp., Sargassum spp., Cystophora spp., and Landsburgia quercifolia) increased mostly in the upper and middle zones, although smaller increases were also observed in the lower zone. Changes in cover of herbaceous, turfing and crustose algae observed in the middle and lower zones were larger than in the upper zone. Density increases of the kelp Ecklonia radiata were observed mainly in the lower zone, although still important in the middle zone. These results show that E. chloroticus can have a strong influence on the structure of algal assemblages in Dusky Sound hence the development of an E. chloroticus fishery in this area should be treated with caution.     

Larval life span of the echinoid evechinus chloroticus (val.)

Newly metamorphosed Evechinus chloroticus (Val.) were observed in three larval cultures 36, 30, and 28 days after fertilisation, indicating that the free swimming larval life may last about 1 month.     

Reproductive periodicity in Evechinus chloroticus in the Hauraki Gulf

Test diameter and gonad volume were recorded over 1 year for bimonthly samples of Evechinus chloroticus (Valenciennes) from each of 3 subtidal populations 10 km apart in the Hauraki Gulf. Histological analysis was used to relate cellular events during gametogenesis to the annual cycle of change in gonad size. Mean gonad sizes of the different sea urchin populations were compared by analysis of covariance. Gametogenesis began in the spring, and major spawning occurred in mid to late summer. The proportion of the gonads taken up by nutritive phagocyte cells increased from autumn to spring. During proliferation and growth of gametes the nutritive phagocytes declined in abundance and globulation, suggesting that reserves stored in these cells were transferred to developing gametes. Gonad size doubled during gametogenesis, declined after spawning, and remained low in autumn and winter. Differences in gonad size between populations were significant during most of the year, and were most pronounced in mid summer. Although synchronous gametogenesis occurred in the 3 populations studied, spawning occurred at different times. This suggested that spawning in this species was induced by factors acting either within sea urchin populations or over distances of a few km or less.     

Stage‐dependent thyroxine effects on sea urchin development

Thyroxine, one of the iodinated hormones produced by vertebrate thyroids, has been reported to accelerate late larval development in several sea urchins (Chino et al. 1994) and in the crown‐of‐thorns starfish (Johnson & Cartwright 1996), but thyroxine effects on earlier portions of echinoderm development have not been reported. I investigated thyroxine effects on developmental rates during several periods spanning development from early cleavage to metamorphosis in the New Zealand sea urchin Evechinus chloroticus (Valenciennes). Thyroxine treatment slowed development between the eight‐cell stage and assembly of the four‐armed pluteus and mid‐larval development between the four‐armed and six‐armed stages. Thyroxine treatment accelerated progress of eight‐armed plutei toward settling, but did not alter the final percentages of larvae that settled and metamorphosed to juvenile urchins. Acceleration of late larval echinoderm development by thyroxine may indicate a relatively ancient evolutionary origin of thyroxine's effects on developmental processes (Johnson 1997).     

Species assemblage and recruitment patterns of echinoderms on shallow rocky reefs in central New Zealand

ABSTRACT

Echinoderms play important ecological roles in the benthic community, but the processes that regulate their distribution are still poorly understood. The aim of this study was to describe the community structure in the shallow rocky reefs of the Wellington region of central New Zealand. Five sites from a harbour and an open coast were surveyed for adult echinoderm density and habitat composition. Additionally, artificial collectors were deployed to assess recruitment patterns. Five taxa were responsible for the assemblage variation within sites and their abundance was highly correlated with habitat composition. Patiriella regularis was highly abundant in all sites, while Coscinasterias muricata and Evechinus chloroticus were dominant in the Harbour. Echinoderm settlement showed interannual variations, as well as differences between locations. There was a significant pulse of C. muricata settlers, while ophiuroids were present in lower numbers but constantly during the studied period. E. chloroticus settlement was sporadic and the absence of a juvenile cohort in the open coast sites suggests that recruitment might not occur for up to 4 years. The present study provides insights on the echinoderm assemblage in the shallow rocky reefs of the Wellington region and contributes to a better understanding of recruitment patterns shaping population structure.     

The effects of trophic interactions and spatial competition on algal community composition on Hawaiian coral reefs

Much of coral reef ecology has focused on how human impacts change coral reefs to macroalgal reefs. However, macroalgae may not always be a good indicator of reef decline, especially on reefs with significant sea urchin populations, as found in Kenya and Hawaii. This study tests the effects of trophic interactions (i.e. herbivory by fishes and sea urchins) and spatial competition (between algae and coral) on algal community structure of reefs surrounding two Hawaiian Islands that vary in their level of human impacts. Reef‐building organisms (corals and crustose coralline algae) were less abundant and turf algae were more abundant on Maui as compared to Lanai, where human impacts are lower. In contrast to previous studies, we found no evidence that macroalgae increased with human impacts. Instead, low turf and macroalgal abundance were best explained by the interactive effects of coral cover and sea urchin abundance. Fishing sea urchin predators appeared to have cascading effects on the benthic community. The absence of sea urchin predators and high sea urchin densities correspond to a disproportionately high abundance of turf and crustose coralline algae. We propose that high turf algal abundance is a better indicator of reef decline in Hawaii than high macroalgal abundance because turf abundance was highest on reefs with low coral cover and few fish. The results of this study emphasize that understanding changes in community composition are context‐dependent and that not all degraded reefs look the same.     

肠道细菌对厚壳贻贝稚贝附着的作用研究

为探讨肠道细菌形成的微生物被膜对贝类附着的作用,从厚壳贻贝(Mytilus coruscus)成体肠道中分离10株肠道细菌,调查厚壳贻贝肠道细菌形成微生物被膜特性,分析微生物被膜密度、细菌种属与厚壳贻贝稚贝附着之间的相互关系。所有肠道细菌均可有效促进稚贝附着。其中,Paracoccus sp.1微生物被膜诱导的稚贝附着率最高(61%),且微生物被膜膜厚较厚,细菌分布较密集;仅5株肠道细菌Roseovarius sp.1、Winogradskyella sp.1、Tenacibaculum sp.4、Bacillus sp.5和Nonlabens sp.1的被膜密度与附着显著相关(P0.05)。系统发育分析发现肠道细菌诱导附着率与其种属无关。本研究表明源于厚壳贻贝成贝肠道细菌可以促进其稚贝的附着,说明肠道细菌对厚壳贻贝的生长发育具有一定的作用。本研究结果为深入探讨肠道细菌与厚壳贻贝相互作用和推动该种规模化养殖提供理论依据。     

Larval life span,larval settlement,and early growth of Evechinus chloroticus (Valenciennes)

Development, settlement, and subsequent metamorphosis on several substrata were observed in cultures of Evechinus chloroticus larvae. The period from fertilisation to metamorphosis ranged between 30 and 63 days for larvae collected from spawnings induced at 3 different times. Newly settled sea urchins collected from the field grew about 1 mm per month in aquaria. Correlation of the larval life span with the growth rate of newly settled sea urchins suggested that the earliest spawning could occur was mid‐November. This finding corroborates the results of previous histo‐logical studies of the gonads of adult sea urchins in the Hauraki Gulf, New Zealand.     

Microbiological studies of thermal habitats of the central volcanic region,North Island,New Zealand

This account of studies on the algae and bacteria of North Island thermal areas records temperature, pH and species found in these microbial habitats, with special attention to organisms living at the highest temperatures. Thermal features were studied at Rotorua (Whakarewarewa and Ohinemutu), Waiotapu (Tourist Reserve and Lady Knox Geyser), Orakei Korako, Taupo Spa, Waikite Springs, Wairakei thermal valley, Wairakei geothermal field, Tikitere, Ketetahi, Lake Rotokawa (Taupo region), Waimangu, De Brett Thermal Hotel (Taupo).

The upper temperature limit for blue‐green algae in New Zealand is 60–65°c, and the species living at the thermal limit is generally Mastigocladus laminosus, although in some cases Phormidium sp. or Synechococcus sp. was found. The Synechococcus sp. characteristic of high temperatures (73–74°c) present in North America was not found in New Zealand. In virtually all boiling pools (99–101°c) with pH values in the neutral and alkaline range bacteria were found, but in acidic boiling pools, bacteria were absent. The presence in New Zealand of the eucaryotic algae Cyanidium caldarium and Zygogonium sp. is reported for the first time. Further records for the hot spring brine fly Ephydrella thermarum and other ephydrids are given. The observations are compared with previous data on thermal habitats in Yellowstone Park, in Iceland, and in other parts of the world.     

Toxicity assessment of New Zealand and Pacific dinoflagellates Ostreopsis and Gambierdiscus (Dinophyceae) extracts using bioassays

The dinoflagellate genus Ostreopsis produces palytoxin-like compounds (PLTXs) and the genus Gambierdiscus produces ciguatoxins (CTXs) and maitotoxin (MTX). Human illness has been recorded following the consumption of CTX-contaminated finfish. Their effects on the flora and fauna in the environment are largely unexplored. Toxin profiles of extracts of Ostreopsis and Gambierdiscus isolates from the Pacific region were characterised using liquid chromatography tandem mass spectrometry. Sea urchin (Evechinus chloriticus) fertilisation was unaffected by any algal extracts, but extracts containing maitotoxin-3 (MTX-3, but not MTX or CTXs), or with high concentrations of PLTXs, were toxic to urchin larval development. Gambierdiscus extracts containing CTXs elicited toxic responses in zebrafish (Danio rerio) embryo toxicity assays; extracts containing only MTX-3 elicited a limited response. Ostreopsis extracts containing PLTXs caused no response. The results demonstrate potential impacts of toxic dinoflagellates on larval organisms and the potential of embryonic assays as toxicity screening tools.     

Bottom-up and top-down control of seagrass overgrazing by the sea urchin Tripneustes gratilla

The lack of top-down control on Tripneustes gratilla, a sea urchin commonly known to graze on seagrass, and the bottom-up control of its feeding preference, led to the overgrazing of seagrass meadows of the species Thalassodendron ciliatum in Changuu Island (Zanzibar Archipelago). The impact of overgrazing on seagrasses was assessed by mapping the presence of grazed versus non-grazed seagrass patches in the study site, while the top-down control on T. gratilla was assessed by measuring the abundance of its fish predators. The feeding preference and distribution of T. gratilla were characterized by calculating the electivity indexes for each seagrass species and measuring sea urchin density, respectively. Approximately half of the patches of T. ciliatum were overgrazed, while predatory fishes of T. gratilla were absent from the site. The Vanderploeg and Scavia's Relativized Electivity Index indicated that T. gratilla had a feeding preference for T. ciliatum, which was also supported by higher urchin densities within T. ciliatum dominated patches. Bottom-up control of grazing activity was observed by quantifying and analyzing morphological, nutritional, and the chemical defense traits of the seagrass in relation to feeding preference and urchin density. Feeding was positively correlated to the seagrass tissue C:P ratio (ρ = 0.9), whereas urchin density showed no correlations. The bottom-up control of the feeding preference and agglomeration of T. gratilla in T. ciliatum meadows, together with the lack of evidence of substantial top-down control and the long recovery time of T. ciliatum led to the overgrazing of this species at this site. Overgrazing, therefore, was shown to be the result of multiple factors ranging from the traits of the seagrass and feeding preference of T. gratilla, to the abundance of predators in this area.     

Low densities of sea urchins influence the structure of algal assemblages in the western Mediterranean

Numerous studies of interactions between urchins and algae in temperate areas have shown an important structuring effect of sea urchin populations. These studies focused almost wholly on the effect of high urchin densities on laminarian forests. In contrast, algal communities below 5–6 m depth in the northwestern Mediterranean are characterised by low sea urchin densities (<5 ind m⁻²) and the absence of laminarian forests. No previous research has addressed sea urchin/algal interactions in this type of community. To determine the effect of the most abundant echinoid species, Paracentrotus lividus, on well-established algal communities in this area, we performed a removal–reintroduction experiment in rocky patches located between 13 and 16 m depth in the northwestern Mediterranean, where sea urchin densities ranged between 0.9 and 3.4 ind m⁻². After 6 months, the cover of non-crustose algae was significantly higher in the plots from which sea urchins had been removed than in control plots (84 vs 67% cover). These removal plots reverted to their original state upon reintroduction of sea urchins. The non-crustose algae consisted of turfing and frondose forms, with the former representing some 70% of the non-crustose algal cover. Change in the cover of turfing algae was responsible for the significant increase in algal development in the sea urchin removal plots. The response of frondose algae to the treatment varied between algal species. It is concluded that grazing by P. lividus exerts a significant effect on habitat structure, even in communities with low sea urchin densities, such as those found in vast areas of the Mediterranean sublittoral.     

4 种经济海藻脂肪酸组成分析

采用改进的Bligh-Dyer法提取脂溶性成分,气相色谱-质谱联用法(GC-MS)进行分离和鉴定,C19:0内标确定总脂及各组分含量,研究了鼠尾藻(Sargassum thunbergii)、浒苔(Enteromorpha prolifera)、龙须菜(Gracilaria lemaneiformis)和红毛菜(Bangia sp.)4种经济海藻的脂肪酸组成及含量。结果表明,4种海藻都检测出C14-C22脂肪酸,总脂含量在12～19 mg/g之间,不饱和脂肪酸为主要组成成分,含量均超过60%。不饱和脂肪酸中以多不饱和脂肪酸(PUFAs)为主,富含n-3和n-6系列PUFAs,n-6与n-3系列PUFAs之比均低于2。比较4种海藻脂肪酸组成特点表明,鼠尾藻以C16、C18和C20为主要组成成分,具褐藻类脂肪酸组成特征;浒苔以C16和C18为主要组成成分,具绿藻类脂肪酸组成特征;龙须菜和红毛菜以C16和C20类脂肪酸为主,具典型红藻类脂肪酸组成特征,同时二者又有不同之处,分别显示真红藻与原始红藻脂肪酸组成的特点。     

Biological features of Pupu Springs

The flora and fauna of Pupu Springs (40°51'S, 172° 46'E) and five other New Zealand cold springs are described. In Pupu Springs there are 16 species of algae, 10 species of bryophytes (including three species of liverworts), and 5 species of angiosperms. The fauna includes a phreatic form (an eyeless planarian, Dugesia sp.), a possible glacial relict (the caddis fly Rakiura vernale), and cold stenotherms (e.g., the caddis fly Psilochorema tautoru). The most abundant animals in the New Zealand springs are Mollusea, Crustacea, and’ larvae of Plecoptera, Diptera, and Trichoptera.

Pupu Springs consist of five biotopes and associated biocoenoses.     

Diet and feeding habits of the sperm whale (Physeter Catodon L.) in the cook strait region of New Zealand

Stomachs of 151 sperm whales were examined at the Tory Channel whaling station in 1963 and 1964. In nine stomachs examined quantitatively there was a 1.69:1 ratio of squid to fish by weight. Some gastroliths were found. The weight of fresh food varied from 12.70 to 105 kg.

Two samples of lower mandibles from squids totalling 2,118 specimens were separated into 11 types and subtypes with the help of a previously published key by M. R. Clarke. These types have been designated: Ai, Aii, Aiii; Bi, Bii, Biii; and C, D, E, F, and G. Some beaks (2.36% of the total) could not be grouped into these categories.

Onychoteuthid squid made up the bulk of the stomach contents by number and weight. The following squid were identified: Nototodarus sloanei, Histioteuthis cookiana, Architeuthis sp., and Moroteuthis sp. The most common fish in the stomachs were: Polypriori oxygeneios (groper), Genypterus blacodes (ling), Hoplostethus sp., an unidentified eel, and Jordanidia solandri (southern kingfish). Other species recorded included Zeus faber (John Dory), Koinga kirki (spined dogfish), Myctophus humboldti (lantern fish), Echinorhinus cooki, and Echinorhinus sp. or Dalatias sp. Quantitative estimates suggested that commercial species of fish were usually less than 32% of the contents by weight.

The feeding habits are discussed.     

Kelp forests in False Bay: urchins vs macroalgae in South Africa’s southwest coast biogeographical transition zone

Kelp forests along South Africa's southwest coast occur in a region of biogeographical overlap. Commonly referred to as transition-zone kelp forests, these dynamic ecosystems are particularly susceptible to grazing from species such as urchins. This study explores relationships between urchins and macroalgae in transition-zone kelp forests along the western side of False Bay. Six kelp forests in this region were sampled. At each site, the urchin Parechinus angulosus and kelp Ecklonia maxima were counted, percentage cover of understorey algae was recorded, and drift algae were collected. Despite variability in urchin and algal cover across sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively associated with macroalgae, although this relationship was weak. A localised threshold of 50 urchins m^–2 was identified, above which kelp density failed to increase above 10 m^–2 and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between drift algae and attached algae. The findings highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, particularly under changing climate trends, experimental research into the feeding behaviour and possible effects of urchins on attached algae in the presence/absence of drift algae is advised.