Inshore Zone Research Articles

PATTERNS OF RUGOSITY ON CORAL REEFS AROUND LAE-LAE, SAMALONA, BARRANG LOMPO AND KAPOPOSANG ISLANDS

Corals have many growth forms, creating many nooks and crannies which provide specialized places for marine organisms to shelter, live, and breed. Reef rugosity is a simple surface roughness measurement; a high rugosity value will support fish communities. This research measured the differences in reef rugosities in four islands in Spermonde Archipelago, Indonesia based on their distance from the mainland and the reef depth. Observation sites were Lae-Lae (LL; inshore zone), Samalona and Barrang Lompo (SA and BL; inner mid-shelf zone), and Kapoposang (KP; outer zone). At each station, rugosity was measured on the reef slope in two depth zones: 3-5 m shallow and 6-10 m deep using chains. The rugosity index at shallow reefs was increasing towards outer zones (Lae-Lae: 0.143 ± 0.015; Kapoposang: 0.655 ± 0.133), which means shallow reefs further from the Sulawesi mainland have more complex structures. There are differences between sites (P-value: 0.0000641) namely LL-BL sites (0.0001675), SA-BL (0.0001873), LL-KP (0.0016070), and SA-KP (0.0018514). At deeper depths, the rugosity was varied with Kapoposang having a higher value (0.451 ± 0.207). The inshore-offshore rugosity patterns in the four sampled islands are likely linked to anthropogenic pressures from the mainland of Sulawesi.

Shifts in biodiversity and physical structure of seagrass beds across 5 decades at Carriacou, Grenadines.

Caribbean seagrass beds are facing increasing anthropogenic stress, yet comprehensive ground-level monitoring programs that capture the structure of seagrass communities before the 1980s are rare. We measured the distribution of seagrass beds and species composition and abundance of seagrass and associated macroalgae and macroinvertebrates in 3 years over a 47-year period (1969, 1994, 2016) at Carriacou, Granada, an area not heavily impacted by local human activity. Seagrass cover and physical parameters of fringing beds were measured in transects at high (HWE) and low wave energy (LWE) sites; frequency of occurrence of all species, and biomass and morphology of seagrasses, were measured at 100 m2 stations around the island. Losses in nearshore seagrass cover occurred at HWE but not LWE sites between 1969 and 2016 and were associated with increases in the seagrass-free inshore zone (SFI) and erosional scarps within beds. Total biomass did not vary across years although there were progressive changes in seagrass composition: a decline in the dominant Thalassia testudinum and concomitant increase in Syringodium filiforme, and establishment of invasive Halophila stipulacea in 2016 at LWE sites. Species richness and diversity of the seagrass community were highest in 1994, when 94% of macroalgae (excluding Caulerpa) were most abundant, and sea urchins were least abundant, compared to 1969 and 2016. Multivariate statistical analyses showed differences in community composition across the 3 years that were consistent with trends in urchin abundance. Increases in SFI and scarp number in seagrass beds at HWE sites occurred mainly after 1994 and likely were related to increased wave forcing following degradation of offshore coral reefs between 1994 and 2016. Our observations suggest that landward migration of seagrass beds with rapidly rising sea level in future will not be realized in reef-protected seagrass beds at Carriacou barring reversal in the processes that have caused reef flattening.

Coral Reef Carbonate Chemistry Reveals Interannual, Seasonal, and Spatial Impacts on Ocean Acidification Off Florida

AbstractOcean acidification (OA) threatens coral reef persistence by decreasing calcification and accelerating the dissolution of reef frameworks. The carbonate chemistry of coastal areas where many reefs exist is strongly influenced by the metabolic activity of the underlying benthic community, contributing to high spatiotemporal variability. While characterizing this variability is difficult, it has important implications for the progression of OA and the persistence of the ecosystems. Here, we characterized the carbonate chemistry at 38 permanent stations located along 10 inshore‐offshore transects spanning 250 km of the Florida Coral Reef (FCR), which encompass four major biogeographic regions (Biscayne Bay, Upper Keys, Middle Keys, and Lower Keys) and four shelf zones (inshore, mid‐channel, offshore, and oceanic). Data have been collected since 2010, with approximately bi‐monthly periodicity starting in 2015. Increasing OA, driven by increasing DIC, was detected in the mid‐channel, offshore, and oceanic zones in every biogeographic region. In the inshore zone, however, increasing TA counteracted any measurable OA trend. Strong seasonal variability occurred at inshore sites and included periods of both exacerbated and mitigated OA. Seasonality was region‐dependent, with greater variability in the Lower and Middle Keys. Elevated pH and aragonite saturation states (ΩAr) were observed in the Upper and Middle Keys, which could favor reef habitat persistence in these regions. Offshore reefs in the FCR could be more susceptible to global OA by experiencing open‐ocean‐like water chemistry conditions. By contrast, higher seasonal variability at inshore reefs could offer a temporary OA refuge during periods of enhanced primary production.

Molecular Identification of Protozoan Sarcocystis in Different Types of Water Bodies in Lithuania.

Representatives of the genus Sarcocystis are unicellular parasites having a two-host life cycle and infecting mammals, birds, and reptiles. Until now, Sarcocystis spp. have been mainly investigated in definitive and intermediate hosts. Only a few studies have been conducted on the detection of Sarcocystis parasites in water samples. The aim of this research was to examine whether the prevalence of Sarcocystis spp. parasitizing farm animals varies in different types of water bodies. Water samples (n = 150) were collected from the entire territory of Lithuania, dividing water bodies into five groups (lakes, rivers, ponds/canals, swamps, and the inshore zone of the territorial Baltic Sea area). One-liter samples were filtered and subsequently analyzed using nested PCR. At least one of the analyzed Sarcocystis spp. (S. arieticanis, S. bertrami, S. bovifelis, S. capracanis, S. cruzi, S. hirsuta, S. miescheriana, and S. tenella) was determined in all examined samples from water bodies. No significant difference in Sarcocystis spp. prevalence between different types of water sources was detected. Our research proved that selecting appropriate primers is important for the accurate identification of parasites in samples collected from water bodies.

Inferred transport of early life stages of Patagonian grenadier (Macruronus magellanicus) between northern Patagonian channels and the continental shelf

Patagonian grenadier migrates from the southwest Atlantic and southeast Pacific to reproduce in the northern Chilean Patagonia. Spawning occurs mainly in winter at the continental shelf break (CSB), but eggs and larvae are also collected inshore of the Chilean Patagonian Estuarine System (PES) during winter and spring. In order to evaluate whether the ontogenetic changes in distribution of early life stages was part of the reproductive strategy of Patagonian grenadier, we analyzed the distribution and transport of eggs and larvae in spring and winter in three channels of the PES (Ninualac, Darwin and Pulluche channels). Ichthyoplankton stratified sampling showed the highest abundances of eggs in the deepest strata, whereas larvae were heterogeneously distributed along the entire water column. Residual current velocities obtained from ADCP indicated seaward (westward) fluxes at the surface in all channels, except in Pulluche in winter. At depth (50–100 m) fluxes were eastward (inshore) in the northern 2 channels but seaward in the southernmost channel. These differences in residual velocities, with variations in the distribution of eggs and larvae, resulted in different landward and oceanward flows of eggs and larvae among channels and strata. Estimated net fluxes in winter suggested that eggs within the channels would either enter the PES from the continental shelf, mainly at the subsurface layer of the Darwin channel, or come from a secondary spawning within this same channel. Eggs and small larvae would be retained at the inshore zone of the Darwin channel, and the more advanced developed stages would be exported through the Pulluche channel back to the continental shelf. The inshore high abundance of eggs and larvae of M. magellanicus in winter, along with the reduced primary production and microbial-based plankton community previously reported, suggest that entering the channels in winter is not a major part of the reproductive strategy of the species. The exportation of larvae from the channels to the shelf in winter, instead, might promote better feeding conditions in offshore waters where larger zooplankton occurs.

Distribution, abundance and sighting patterns of multiple stocks of bottlenose dolphins (Tursiops truncatus) in coastal Virginia waters

Three stocks of bottlenose dolphins (Tursiops truncatus) are currently known to co‐occur in the coastal waters off Virginia. A combination of visual line‐transect survey and photo‐identification (photo‐ID) methods was used to gather information on the occurrence, distribution and density of bottlenose dolphins in the coastal areas of Norfolk and Virginia Beach. Sixty‐one line‐transect surveys were completed in two zones (inshore and offshore) between August 2012 and August 2015, with on‐effort coverage of 6,550 kilometres (km) of trackline over 349.6 hours. Conventional line‐transect analysis of bottlenose dolphin sightings showed both spatial and temporal variation in density (D) and abundance (N), with highest density in the inshore zone during warm‐water months (June–November). Inshore densities were calculated as 3.51 individuals per square kilometre (km2) (N = 1,090) in the warm‐water season and 0.73 individuals/km2 (N = 225) in cool‐water months (December–May). Densities in the offshore zone were 1.24 individuals/km2 (N = 741) in the warm‐water season and 0.61 individuals/km2 (N = 366) in the cool‐water season. Warm‐water density peaks support previous research; however, this study documents a cold‐season presence of dolphins in both zones not previously reported. Twenty‐seven photo‐ID surveys were completed and a photo‐ID catalogue was created using photos taken during both dedicated photo‐ID and line‐transect surveys, containing 1,335 unique individuals. Re‐sighting numbers were low, with less than 17% of individuals documented on more than one occasion, and only 4% sighted on three or more occasions, with a maximum of 4 re‐sightings. Days between re‐sightings ranged from 5 to 970, though distance between re‐sightings spanning greater time was minimal (less than 25km). Sighting locations of photo‐IDed dolphins were broken into three regions to investigate seasonal and spatial patterns of individual distribution; dolphins sighted only in the Cape Henry (CH) or Inner Bay (IB) region were observed mostly during summer and fall seasons (93% CH, 100% IB) with none occurring during winter. For the Outer Coastline (OC) region, the majority of sightings (88%) occurred during fall and winter. Additionally, there were two individuals sighted during winter months also sighted during summer more than 130km to the north inside Chesapeake Bay (matched to a different catalogue). These sightings support the possibility that the current stock structure does not account for all dolphins in the region. Stock structure as currently understood is complicated, with overlapping spatial distribution of three stocks that separate seasonally. Our study provides information that may be useful for management, but also additional findings that could impact future stock designations

PROBABILITY ASSESSMENT OF CROSSING SITUATION IN SUNDA STRAIT

The new routeing measures in Sunda Strait, that consists of traffic separation scheme (TSS), precautionary area (PA), and inshore traffic zones (ITZ), have been implemented since July 2020. The Automatic Identification System (AIS) data is utilized to understand the traffic pattern in this area. One dataset before and one dataset after the implementation of TSS is then converted into a vessel trip database. Eight vessel courses, two positions, and seven crossing zones are determined from the density plot to categorise the vessel trips. This study introduced a different perspective to assess the crossing situation by using three point-of-views to calculate the probability, namely crossing zone basis, course basis, and vessel type basis. The analysis result shows that the crossing situation is mostly occurred in the precautionary area of the new routeing measure.

Salt tolerance of halotolerant bacteria from coastal soils and sediments near saltern field of Hainan Island, China.

Understanding the salt tolerance of microbial communities may help to elucidate the effects of salt concentration and other environmental factors on soil biodiversity. Here, high-throughput sequencing of 16S rDNA and ITS was combined to investigate the distribution and salt tolerance of microbial communities in coastal soils and sediments near the Yinggehai saltern field of Hainan Island, China. The microbial communities in the soils and sediments of the land zone (YGHLS), the intertidal zone (YGHIS), and the inshore zone (YGHWS) were compared. PCoA of weighted and unweighted UniFrac distance revealed obvious differences in soil microbial community among different samples. ANOSIM analysis could clearly separate the three samples from each other. Three halotolerant bacteria, including Halomonas, Halobacillus and Wallemia, were found in the samples, which accounted for 0.0335 ± 0.0586%, 0.0241 ± 0.0304%, and 0.0308 ± 0.0445% of the total microbial community, respectively. The relative abundance of Trk system potassium uptake protein, Kdp operon response regulator, and Na+/H+ antiporter in the samples exceeded 0.09%, 0.06%, and 0.02%, respectively, indicating that the Trk system plays a major role in the salt tolerance of halotolerant bacteria in Yinggehai coastal soils and sediments.

Importance of a turbulent river section below a giant waterfall for fish spawning: Indications from drift and dispersion patterns of early life stages

AbstractSeasonal drift patterns of fish eggs and larvae were analysed along the river section downstream the Iguaçu River Falls to the confluence with Paraná River, over three spawning seasons. This river section is situated in a narrow rocky canyon characterized by a steep slope, which leads to highly turbulent and fast flowing conditions in a series of rapids. Water transit time in this river stretch of 20 km was short (5–11 h), the flow‐velocity in rapids can reach values of more than 6 m s−1. Densities of drifting eggs and larvae varied between three spawning seasons, and differences of eggs were more pronounced compared to larvae. Eggs and larvae were observed all along the river section. A spatial, longitudinal distribution pattern of larvae was found, with higher numbers in the upper section. A distinct spatial sequence of different embryonic stages was observed, with the highest abundance of early stages. Larval densities were low in comparison to egg densities, and preflexion and flexion stages predominated. High abundance of buoyant eggs in drift indicates fish spawning in rapid and turbulent waters of the Iguaçu River, particularly downstream from the Iguaçu Falls. Rainfall and turbidity may be the main trigger for spawning. Spawned eggs drifted quickly towards the confluence, most are likely to hatch in the Paraná River, while larvae disperse to nursery habitats even in the river section below the falls. Thus, inshore zones along the whole stretch provide nursery habitats for larval development of fish species exhibiting different reproductive strategies.

Krill availability in adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Antarctica

AbstractThe Palmer Deep canyon along the West Antarctic Peninsula is a biological hotspot with abundant phytoplankton and krill supporting Adélie and gentoo penguin rookeries at the canyon head. Nearshore studies have focused on physical mechanisms driving primary production and penguin foraging, but less is known about finer‐scale krill distribution and density. We designed two acoustic survey grids paired with conductivity–temperature–depth profiles within adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Antarctica. The grids were sampled from January to March 2019 to assess variability in krill availability and associations with oceanographic properties. Krill density was similar in the two regions, but krill swarms were longer and larger in the gentoo foraging region, which was also less stratified and had lower chlorophyll concentrations. In the inshore zone near penguin colonies, depth‐integrated krill density increased from summer to autumn (January–March) independent of chlorophyll concentration, suggesting a life history‐driven adult krill migration rather than a resource‐driven biomass increase. The daytime depth of krill biomass deepened through the summer and became decoupled from the chlorophyll maximum in March as diel vertical migration magnitude likely increased. Penguins near Palmer Station did not appear to be limited by krill availability during our study, and regional differences in krill depth match the foraging behaviors of the two penguin species. Understanding fine‐scale physical forcing and ecological interactions in coastal Antarctic hotspots is critical for predicting how environmental change will impact these ecosystems.

Connectivity in early life stages of the southern hake, Merluccius australis, in northern Chilean Patagonia

The southern hake, Merluccius australis, is one of the most important marine fishery resources in Chilean Patagonia. However, little is known about its early life history, especially the transport of eggs and larvae and the connectivity between spawning and nursery areas. An individual-based model (IBM) of the early life stages of M. australis, coupled to a hydrodynamic model, was used to track virtual individuals released from known spawning locations and identify potential nursery areas. The simulations were used to assess connectivity and retention of M. australis eggs and yolk-sac larvae within (and between) the continental shelf (offshore) and the inner sea (inshore) zones. The inshore zone included two spawning and nursery areas (Inner Sea of Chiloé (ISCh), Inner Sea of Moraleda Channel ISM)) and the offshore zone included three spawning and nursery areas (Guafo Island, Guamblin Island, and the Taitao Peninsula). The hydrodynamic model was validated using available observations (oceanographic surveys and the World Ocean Atlas 2018) for winter and spring, periods during which M. australis reproductive activity peaks. The IBM reproduced well the observed seasonal variability of egg and larval distributions. Individuals from the offshore spawning areas had low connectivity with those in the inshore nursery areas in winter and spring. However, individuals from the inshore spawning areas showed a high degree of connectivity with one of the offshore nursery areas (Guafo) during winter and spring, but low connectivity between the inshore ones (ISCh and ISM). Guamblin (in winter) and ISCh (in spring) were the most important retention areas. A conceptual model is proposed to represent the connectivity in early developmental stages between the spawning and nursery areas of M. australis: ichthyoplankton is transported from inshore to offshore in winter when little spawning occurs inshore, but not in spring when spawning and retention increases inshore. Retention in the offshore zone in winter is significant, with almost no connectivity with the inshore zone. Since the main spawning of the species occurs in winter in the offshore zone and secondarily in the inshore zone in spring, the seasonal differences in dispersal patterns seem to be part of the reproductive strategy of the species, which apparently confers advantages for the offspring by promoting development in the most advantageous feeding environment for each season (offshore in winter and inshore in spring).

Elucidating trophic pathways of the most abundant fish larvae in northern Patagonia using δ13C and δ15N isotopes

The alternation of the classic and microbial food-webs in spring and winter, respectively, and the trespass towards higher trophic levels represented by fish early stages, are not well understood in Patagonia. These trophic routes were investigated in the inner Sea of Chiloe, an estuary of high ecological relevance in northern Patagonia. The isotopic values of δ13C and δ15N of ichthyoplankton and particulate organic matter were analyzed in late winter and spring 2017 to evaluate whether seasonal changes (e.g. in the composition of the freshwater discharge) were reflected in the isotopic signals of fish larvae. For this purpose, larvae of dominant fish species with contrasting feeding strategies were collected up to 100 m depth. The inshore zone of northern Patagonia was characterized by a dominance of marine carbon production, with increasing input of terrestrial organic matter during winter. δ13C values < -25 ‰ at the outermost estuary stations indicated the influence of allochthonous carbon exported from the inshore area in spring. The δ13C-larval signature of the species of the lightfish Maurolicus parvipinnis, the pipefish Leptonotus blainvilleanus, and the rockfish Sebastes oculatus followed the isotopic signature of the particulate organic matter in both seasons, at inshore and the exchange (outer) zone. Food partitioning was detected between species, with Merluccius spp. at the highest trophic position and L. blainvilleanus at the lowest. The fish larval community reached more diverse and higher δ15N values in winter, when larvae likely fed on prey items of higher trophic level, or instead when the food-web was partly sustained by microbial sources. Our results showed seasonal variations in δ13C values, suggesting differences in the source of organic carbon incorporated by the studied fish larvae. Moreover, trophic plasticity at larval stages may be an important characteristic of this type of estuarine environment.

Ichthyoplankton distribution and feeding habits of fish larvae at the inshore zone of northern Patagonia, Chile

The Inland Sea of Chiloe is a semi-enclosed sea of northern Patagonia characterized by freshwater inputs from a fjord in the north and high influence of offshore waters in its southern sub-basin. The zone has been referred to as an important fish nursery ground. In order to assess its relevance as a spawning ground and the strategies for temporal coexistence of larvae of fish species from diverse origins in these inshore waters, we investigated both the horizontal and vertical distributions, and the feeding habits of early stages of fish during the period of highest productivity (austral spring). Ichthyoplankton richness and abundance were higher in the northern sub-basin, dominated by the offshore midwater lightfish Maurolicus parvipinnis, and the shelf-break and demersal hake Merluccius gayi. The larvae of the coastal rockfish Sebastes oculatus and the clupeid Strangomera bentincki were more abundant in surface waters, while the larvae of Merluccius australis, M. gayi, and M. parvipinnis reached deeper waters. The co-occurring inshore larvae of M. gayi, M. parvipinnis, and S. oculatus preyed actively at day and night times on a wide spectrum of zooplankton sizes, with the small calanoid copepods being the most commonly consumed food items in the largest larvae of M. parvipinnis and M. gayi. Nauplii were frequent food items for smaller larvae of M. parvipinnis, S. oculatus, and S. bentincki. The high spring productivity and the large abundances of potential zooplanktonic prey, along with larval spatial segregation, are visualized as the main factors enabling species with different origins to co-inhabit and grow at inshore waters in northern Patagonia.

The White Sea threespine stickleback, Gasterosteus aculeatus, differentiation at the beginning of spawning by the activity of calcium-dependent proteases and population characteristics

Threespine stickleback Gasterosteus aculeatus of theWhite Sea perform spawning migrations from the wintering areas to the inshore zone in early summer. To describe the spatial heterogeneity of the spawning agglomerations of stickleback, we compared size characteristics and biochemical parameters in different organs of spawners from three locations of theKandalakshaBay. The sampling locations are situated within a few kilometers from each other but notably differing in temperature regime, feeding resources, and underwater vegetation. The samples have been collected within a week after appearance of fish in the inshore zone. We did not find differences between samples by size characteristics. The activity of intracellular calcium-dependent proteases (calpains) significantly differed in fish from different samples. The results obtained can be explained by both the initial genetic differences of fish from different spawning grounds or the response of initially homogeneous groups of sticklebacks to different environmental conditions. The first explanation is supported by the fact that quite long time of living in new conditions is required to result in differences in calpain activity, and the time, which passed after the separation of spawners in our sampling locations is likely not sufficient for such differentiation. The second explanation is supported by studies of winter distribution of stickleback in the area showing that the wintering areas are quite far from the inshore zone and mixing in wintering locations preventing population structuring can be supposed. Moreover, the patterns of calpain activity are more similar in fish caught under more similar conditions, which may indicate environmental reasons of the observed biochemical differences. By the moment, we have no reason to prefer one explanation to another. For that, it is needed to perform studies on size and biochemical distribution of stickleback at later stages of the spawning.

Fishing in a congested sea: What do marine protected areas imply for the future of the Maltese artisanal fleet?

Inshore artisanal fishing in Malta is under intense spatial competition as the coastal zone is fragmented by multiple uses and designations including maritime transport, infrastructure, industrial fisheries, aquaculture, tourism and recreation. This research, adopting a grounded visualization methodology, explains how the artisanal fishing sector has undergone and been affected by ‘spatial squeezing’. Our results show that artisanal fishermen have been forced to give up fishing grounds or co-exist with other uses to the point where the ability to fish is becoming increasingly challenging. These difficulties might escalate with the advent of the marine protected areas (MPAs) which encompass nearly half of the inshore fishing zones. Since there does not seem to be effective MPA consultation mechanisms that elicit the real social, cultural and economic value of artisanal fishing grounds, fishermen feel threatened, alienated and disempowered. This study urges for a more holistic approach to spatial marine planning and accentuates the need of realizing the dependency of the artisanal sector on the inshore zones in the implementation of conservation measures, such that the prolonged existence of the coastal fishing communities is not jeopardized.

Downstream migration and mechanisms of dispersal of young fish in rivers

Downstream migration (DSM) of young fish has traditionally been considered a passive process. A review of studies of the patterns and mechanisms of DSM showed that it met the main criterion for migration: that animals move between well-defined habitats according to a predictable schedule. During DSM, fish often leave the habitat in which they reside (inshore zone) and enter a migratory habitat (main channel). DSM is manifested at a seasonal or diel scale and in species-specific spatial distribution patterns. According to our “dispersal with low dilution” hypothesis, the supposed adaptive value of DSM is due not only to dispersal but also to maintenance of aggregations and synchronization of migratory activity. Temporal and spatial peaks of migration promote efficient intraspecific interactions, such as shoaling, and the integrity of populations. We conclude that migratory behaviour is most successful in habitats with optimum complexity and that the influence of behaviour on DSM is most important at key periods and sites (twilight windows and interfaces between habitats).

Identification of subspecies of European anchovy Engraulis encrasicolus (Engraulidae) in the wintering aggregations based on morphological parameters of otoliths

A new method of identification of the Sea of Azov and Black Sea subspecies of European anchovy Engraulis encrasicolus in mixed wintering aggregations is suggested based on discriminant analysis using a morphological parameter, the angle of the central groove of the otolith. This angle differs significantly in the subspecies, ranging between 92° and 148° and between 55° and 95° in the Azov and Black Sea subspecies, respectively. In the Azov anchovy, the difference between the eastern and western populations in the angle of the central groove is not registered. The classification equations obtained in the study can be used for subsequent assessment of the ratio between the abundances of each subspecies in mixed aggregations of European anchovy in the inshore zone of Crimea.

Assemblage characteristics and diet of fish in the shallow coastal waters of James Ross Island, Antarctica

This study presents data on fish assemblage structure for the relatively pristine and understudied Antarctic coastal zone (5-25 m). A total of 545 Notothenioidei and Bathydraconidae fish (eight species) were caught in the Prince Gustav Channel (James Ross Island, eastern Antarctic Peninsula) using Nordic multi-mesh benthic gill nets between January and February 2014. Trematomus hansoni dominated at 5 m and T. bernacchii at 15 m, with Gobionotothen gibberifrons and T. newnesi subdominant. Dominance at 25 m resembled that at 15 m. Despite relatively low numbers, species richness, abundance and biomass appeared to increase with depth. While T. bernacchii, T. hansoni, G. gibberifrons and Notothenia coriiceps all displayed multiple size (and probably age) groups, most T. newnesi ranged between 10-15 cm. Sub-samples of G. gibberifrons and T. bernacchii showed a 1:1 adult/immature ratio, with minimum adult and maximum immature length/weight overlapping. Females outnumbered males, with a ratio of 2.8:1 for G. gibberifrons and 4.8:1 for T. bernacchii. The diet comprised mostly benthic taxa (isopods, gammarids, gastropods, polychaete worms). While G. gibberifrons appeared opportunistic, T. bernacchii specialised more on isopods. Our results highlight the possible importance of the Antarctic inshore zone as feeding habitat; despite frequent ice cover/scouring. We suggest that recent prolonged summer ice cover over the eastern side of the Antarctic Peninsula could have important impacts on inshore fish communities and food webs, though further in-depth studies are needed to confirm our results.

Decoupled Seasonal Stress as an Indication of Chronic Stress in <i>Montastraea cavernosa</i> and <i>Porites astreoides</i> Inhabiting the Florida Reef Tract

Although mass mortality from disease and climate anomalies are largely to blame for rapid losses in coral cover along the Florida reef tract, the failure of extant populations to recolonize the offshore zone is puzzling given improvements to water quality and narrower range in seawater temperature compared to the inshore patch reef zone. Using existing data from the Coral Reef Environmental Monitoring Program (CREMP) and from an inshore and offshore site established to compliment this dataset we identified significantly increased abundance and diversity of scleractinian coral from inshore to offshore across the Florida reef tract. Applying exploratory statistical methods we identified two abundant species, Montastraea cavernosa and Porites astreoides , inhabiting both zones to varying degrees. Following reciprocal transplantation of conspecifics between a representative offshore and inshore reef (6 m depth), we monitored monthly coral colony brightness (a measurement related to endosymbiotic dinoflagellate density) over a two-year period to examine symbiont loss, a common stress response in scleractinian corals. Although species-specific stress patterns were not identified, zone-specific variation was evident. Trigonometric regression of stress level by month revealed a significant relationship supporting an annual stress and recovery period at the inshore patch reef zone. Contrary to this result, conspecifics transplanted to the offshore zone did not display recovery resulting in a continued chronically bleached state over the two-year period. Our results implicate alleviation or decreased stress at inshore sites and the importance of extending greater protection to reefs within this zone.

Feasibility Analysis of MERIS as a Tool for Monitoring Lake Guiers (Senegal) Water Quality

ENVISAT/MERIS scenes of Lake Guiers covering the period 2003-2010 were processed for concentration retrieval of chlorophyll a (CHLa), suspended particulate matter (SPM) and colored fraction of dissolved organic matter (CDOM), i.e. the three main parameters relevant to the water quality management of the lake. Estimates in the range of 30 - 117 μg CHLa L-1 (average 62.13 μg·L-1), 0.10 - 29.0 mg SPM L-1 (average 22.01 mg·L-1), and 1.10 - 1.90 CDOM m-1 (average 1.33 m-1) were recorded, suggesting the possibility of occasional poor quality waters in some compartments of the lake. The values calculated as part of this study are consistent with literature data. On the basis of these estimates, interpretations were made as to the feasibility of applying MERIS data for synoptic environmental monitoring purposes. The data were subjected to statistical analysis, including regression analysis and significance tests. Estimates of CHLa and CDOM revealed some level of correlation, which suggests that phytoplankton biomass degradation may account for nearly 47% of the dissolved optical compounds CDOM. Notable areas of high CHLa and CDOM concentrations are found in the southern inshore zone, an environment with less water agitation. In contrast, SPM concentrations tend to increase in environments of very shallow water marked by high water turbulence and bottom mobility. However, it was not possible to fully assess the model performance and detection accuracy of the results due to lack of ground truths. Nonetheless, the results show concentrations that compared well with the insitu data from earlier studies and data reported elsewhere from other lacustrine systems. Therefore, it can be inferred from this study that MERIS data present a useful low-cost (i.e. cost effective and readily available) approach for environmental monitoring of Lake Guiers waters with excellent spatial coverage. In addition, the study highlighted the minimal effect of the so-called “bottom effect” on model predictions, despite the small depth of the lake.