| 1. |
- Björnerås, Caroline, et al.
(författare)
-
Inland blue holes of The Bahamas - chemistry and biology in a unique aquatic environment
- 2020
-
Ingår i: Fundamental and Applied Limnology. - : Schweizerbart science publishers. - 1863-9135. ; 194:2, s. 95-106
-
Tidskriftsartikel (refereegranskat)abstract
- While lake systems in temperate regions have been extensively studied, tropical and subtropical systems have received less attention. Here, we describe the water chemistry and biota of ten inland blue holes on Andros Island, The Bahamas, representative of the morphological, abiotic, and biotic variation among Androsian inland blue holes. The majority of the studied blue holes were vertically stratified with oxic freshwater overlying anoxic saline groundwater of marine origin. Water chemistry (e.g. total phosphorus and nitrogen) in shallow waters was similar among blue holes, while turbidity and water color varied. Presence of hydrogen sulfide and reduced iron in and below the halocline indicate reducing conditions in all stratified blue holes. The biota above the halocline was also similar among blue holes with a few taxa dominating the phytoplankton community, and the zooplankton community consisting of copepods and rotifers. The Bahamas mosquitofish (Gambusia hubbsi) was present in all investigated blue holes, often accompanied by other small planktivorous fish, while the piscivorous bigmouth sleeper (Gobiomorus donnitor) was only present in some of the blue holes. Our field study reinforces that inland blue holes are highly interesting for biogeochemical research, and provide naturally replicated systems for evolutionary studies.
|
|
| 2. |
- Lee, Marcus, et al.
(författare)
-
Low-latitude zooplankton pigmentation plasticity in response to multiple threats
- 2019
-
Ingår i: Royal Society Open Science. - : Royal Society Open Science. - 2054-5703. ; 6:7, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation ( UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian 'blue hole' copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.
|
|
| 3. |
- Pärssinen, Varpu, et al.
(författare)
-
Variation in predation regime drives sex-specific differences in mosquitofish foraging behaviour
- 2021
-
Ingår i: Oikos. - : Wiley-Blackwell. - 0030-1299 .- 1600-0706. ; 130:5, s. 790-797
-
Tidskriftsartikel (refereegranskat)abstract
- Predation is a well-studied driver of ecological selection on prey traits, which frequently drives divergence in anti-predator performance across environments that vary in predation risk. However, predation also alters prey mortality regimes, where low predation risk often results in higher prey densities and consequently higher intensities of intraspecific resource competition. In addition, predation risk alters the foraging context, as acquiring food can be risky in the presence of predators. Thus, different predation regimes can drive divergent selection on traits associated with resource competition, such as foraging behaviours. Moreover, because sexes often differ in susceptibility to predation and limitations to their reproductive output, the intensity of the tradeoff between predator avoidance and resource competition may depend on sex. We used a laboratory experiment to assess key aspects of foraging performance in a predator-free context in Bahamas mosquitofish Gambusia hubbsi wild-caught from multiple populations that experience either high or low levels of predation risk. When competing for limited food resources at a common density, females from low-predation regimes showed higher foraging and food consumption rates than females from high-predation regimes. Males showed fewer differences between predation regimes, and an opposite pattern from females. We suggest these sex-specific effects result from females facing a greater tradeoff between predation risk and resource competition, combined with males from high-predation environments elevating foraging behaviours in the absence of nearby predators and females. Females of this species are larger than males, bear live young and show higher foraging rates in the wild than males. On the other hand, males spend more time pursuing females in the wild, and may exhibit greater flexibility in foraging behaviours based on the immediate context. Our results show that varying levels of predation risk can lead to differences in behaviours associated with resource competition, but these effects can strongly differ between sexes.
|
|
| 4. |
- Sha, Yongcui, et al.
(författare)
-
Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes
- 2021
-
Ingår i: Aquatic Ecology. - : Springer. - 1386-2588 .- 1573-5125. ; 55:4, s. 1157-1169
-
Tidskriftsartikel (refereegranskat)abstract
- Diel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophyll a), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM may vary among systems, but also systematically by latitude.
|
|
